Despite being one of the most dependable methods used by applied mathematicians and engineers in handling complex systems, the finite element method commits variational crimes. This paper contextualizes the concept of variational crime within a broader account of mathematical practice by explaining the tradeoff between complexity and accuracy involved in the construction of numerical methods. We articulate two standards of accuracy used to determine whether inexact solutions are good enough and show that, despite violating the justificatory principles (...) of one, the finite element method nevertheless succeeds in obtaining its legitimacy from the other. (shrink)

Solid-state processing of metal material is a very complex physical and chemical process, which is coupled by a series of variations including heat transfer, momentum transfer, mass transfer, and phase change. Applying three-dimensional finite element numerical method to the simulation of solid-state processing can perform analysis of metal material’s forging processes before production trial production, can obtain their relevant information such as material flow law, temperature field, and strain field under the minimum physical test conditions, thereby predicting (...) metal material’s forming defects and improving their forging quality. On the basis of summarizing and analyzing previous research works, this paper expounded the current status and significance of solid-state processing of metal materials, elaborated the development background, current status, and future challenges of 3D finite element numerical simulation, introduced the discrimination method and free surface solution method of numerical simulation calculation, conducted finite element model’s geometric assumptions, material selection, element division, model establishment, parameter selection, and initial and boundary condition determination, and simulated and analyzed rheological casting, remelting heating, thixoforming, and rotary piercing processes of metal materials. The results show that the 3D finite element numerical method can not only simulate various processes of flow field, temperature field, stress field, and microstructure in solid-state processing but also can provide a reliable basis for effectively obtaining a reasonable description and finding a more optimized design plan for metal material processing in a short time, which plays an important role in understanding and analyzing solid metal forming process, controlling and optimizing process parameters, guiding and mastering rheological casting, and secondary heating and rotary piercing of metal materials. (shrink)

In this paper, we present an intensive investigation of the finite volume method compared to the finite difference methods. In order to show the main difference in the way of approaching the solution, we take the Burgers equation and the Buckley–Leverett equation as examples to simulate the previously mentioned methods. On the one hand, we simulate the results of the finite difference methods using the schemes of Lax–Friedrichs and Lax–Wendroff. On the other hand, we apply Godunov’s (...) scheme to simulate the results of the finite volume method. Moreover, we show how starting with a variational formulation of the problem, the finite element technique provides piecewise formulations of functions defined by a collection of grid data points, while the finite difference technique begins with a differential formulation of the problem and continues to discretize the derivatives. Finally, some graphical and numerical comparisons are provided to illustrate and corroborate the differences between these two main methods. (shrink)

The mathematical model of physical problems interprets physical phenomena closely. This research work is focused on numerical solution of a nonlinear mathematical model of fractional Maxwell nanofluid with the finite difference element method. Addition of nanoparticles in base fluids such as water, sodium alginate, kerosene oil, and engine oil is observed, and velocity profile and heat transfer energy profile of solutions are investigated. The finite difference method involving the discretization of time and distance parameters is (...) applied for numerical results by using the Caputo time fractional operator. These results are plotted against different physical parameters under the effects of magnetic field. These results depicts that a slight decrease occurs for velocity for a high value of Reynolds number, while a small value of Re provides more dominant effects on velocity and temperature profile. It is observed that fractional parameters α and β show inverse behavior against u y, t and θ y, t. An increase in volumetric fraction of nanoparticles in base fluids decreases the temperature profile of fractional Maxwell nanofluids. Using mathematical software of MAPLE, codes are developed and executed to obtain these results. (shrink)

This contribution sheds light on the role of infinite idealization in structural analysis, by exploring how infinite elements and finite element methods are combined in civil engineering models. This combination, I claim, should be read in terms of a ‘complementarity function’ through which the representational ideal of completeness is reached in engineering model-building. Taking a cue from Weisberg’s definition of multiple-model idealization, I highlight how infinite idealizations are primarily meant to contribute to the prediction of structural behavior in (...) Multiphysics approaches. (shrink)

This contribution sheds light on the role of infinite idealization in structural analysis, by exploring how infinite elements and finite element methods are combined in civil engineering models. This combination, I claim, should be read in terms of a ‘complementarity function’ through which the representational ideal of completeness is reached in engineering model-building. Taking a cue from Weisberg’s definition of multiple-model idealization, I highlight how infinite idealizations are primarily meant to contribute to the prediction of structural behavior in (...) Multiphysics approaches. (shrink)

This paper addresses the issues related to designing and estimating the strength of solid-alloy elements in the deforming broaches of significant diameter (exceeding 150 mm) for the developed process of discrete broaching. The tool limit condition was assessed based on two strength criteria: the specific potential energy of shape change and the maximum tangent stresses. Numerical modeling using the finite element method has made it possible to derive the distribution of equivalent stresses in the tool elements and (...) the contact stresses at the surface of the contact between a solid-alloy insert and the body, which enabled the analysis of tool strength under loading. The simulation was performed under a single normal load, which ensured the versatility of the calculation for any contact pressure values. We have derived formulae to calculate the acceptable contact pressure depending on unit load. The effect of the insert protrusion height over the body on the strength of tool elements has been established. We have derived engineering dependences that determine the required magnitude of insert protrusion over the body depending on the ultimate load. An example of calculating the strength of a prefabricated deforming element in the machining of a sleeve made from gray modified cast iron of hardness HB230 has been considered. Our calculations have shown that the deforming element designed for the new technological process corresponds to the conditions of strength, provided the ratio h1/h=0.15 is maintained (where h1 is the insert height above the body, h is the insert height). The results obtained could be used in engineering calculations when designing the prefabricated tool for discrete deformation, as well as to assess the strength of prefabricated tools, such as cutters, core drills, reamers, when refining external loads. (shrink)

In order to obtain a new structure of beam flexure hinge with good performance, the flexure hinge based on the X-lattice structure is researched in this paper. The truss model in the finite element method is used to model the 6-DOF compliance of the flexure hinge based on the X-lattice structure. The influence of structural parameters on the compliance and compliance ratio of flexure hinges is analyzed based on this model, and the performance is compared with the (...) traditional beam flexure hinge of the same size. In order to design a flexure hinge based on the X-lattice structure with good comprehensive performance, this paper proposes an intelligent structure optimization method based on a genetic algorithm. The feasibility of the optimization algorithm is verified by an example. (shrink)

Let φ be a monadic second order sentence about a finite structure from a class K which is closed under disjoint unions and has components. Compton has conjectured that if the number of n element structures has appropriate asymptotics, then unlabelled (labelled) asymptotic probabilities ν(φ) (μ(φ) respectively) for φ always exist. By applying generating series methods to count finite models, and a tailor made Tauberian lemma, this conjecture is proved under a mild additional condition on the asymptotics (...) of the number of single component K-structures. Prominent among examples covered, are structures consisting of a single unary function (or partial function) and a fixed number of unary predicates. (shrink)

This research aims to evaluate the calculation accuracy and efficiency of the artificial neural network-based important sampling method on reliability of structures such as drum brakes. The finite element analysis result is used to establish the ANN sample in ANN-based reliability analysis methods. Because the process of FEA is time-consuming, the ANN sample size has a very important influence on the calculation efficiency. Two types of ANNs used in this study are the radial basis function neural network (...) and back propagation neural network. RBF-IS and BP-IS methods are used to conduct reliability analysis on training samples of three different sizes, and the results are compared with several reliability analysis methods based on ANNs. The results show that the probability of failure of the RBF-IS method is closer to that of the Monte-Carlo simulation method than those of other methods. In addition, the RBF-IS method has better calculation efficiency than the other methods considered in this study. This research demonstrates that the RBF-IS method is well suited to structure reliability problems. (shrink)

We present a theory that copes with the dynamics of inconsistent information. A method is set forth to represent possibly inconsistent information by a finite state. Next, finite operations for expansion and contraction of finite states are given. No extra-logical element — a choice function or an ordering over (sets of) sentences — is presupposed in the definition of contraction. Moreover, expansion and contraction are each other's duals. AGM-style characterizations of these operations follow.

The article analyzes the features of understanding of the history of philosophical process by the leading representative of French Neo-Kantianism. The binary scheme, thoroughly substantiated by Renоuvier in the “Sketch of the Systematic Classification of Philosophical Doctrines”, was a certain result of his previous creative way. In the “Textbook of Philosophy of the New Age”, he, highlighting the pantheism–idealism dilemma, expresses his sympathies for eclecticism. In the “Textbook of Ancient Philosophy”, he advocates giving philosophy a scientific character by combining the (...) laws of reason and history. In “Experiences of General Criticism” he builds a system of neo-criticism, identifying phenomena with reality. Finally, the “Sketch” presents an attempt at an objective consideration of the history of philosophy. Renоuvier identifies six oppositions passing through the entire history of thought (thing–consciousness, infinite–finite, evolution–creation, necessity–freedom, happiness–duty, evidence–belief). The strength of his method is the desire to make a choice between opposing trends, taking into account intellectual motives, passions, practical inducements of varying degrees of community. But both elements of reductionism and unfounded optimism about the lack of influence of all kinds of systems on his own constructions are present in his approach. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:METHOD DIVORCED FROM CONTENT IN THEOLOGY? AN ASSESSMENT OF LONERGAN'S METHOD IN THEOLOGY TERRENCE REYNOLDS Brown University Providence, Rhode Island IN IDS INTRODUCTION to Method in Theology, Bernard Lonergan flatly maintains that he intends to· write not theology but only method in theology.1 He therefore proposes.to concern himself solely with the operations theologians perform and to suspend consideration of the objects they seek to expound. (...) He is looking for "a normative pattern of recurrent and related operations yielding cumulative and progressive results." 2 To arrive at his method, Lonergan relies upon the cognitional theory which he ha,d outlined with great sophistication in Insight. He argues that the dynamism of the human mind and the principles of its operations as revealed by introspective psycihology lead to a model of the nature of scientific method in general and, by extension, to method in theology. It is through the transcendental method that Lonergan discovers in the procedures of the human mind the basic pattern of operations by which wl1l cognitiona1 activity takes plaice. This pattern, he maintains, yields cumulative results in thelogical inquiry as well as in any fie1d of investigation. He therefore intends to demonstrate that theology can be studied in the same manner as any other discipline. Critics have respectfully suggested that, while Lonergan's system is an imposing one, he has introduced unworkable and 1 Bernard Lonergan, Method 4ln Theology (New York, 1979), p. XII. 2 Lonergan, Method, p. 5. 245 246 TERRENCE REYNOLDS misleading distinctions into his work; in particular, he has fa~led to explicate his thoologiicaJ. p11emises and thereby leaves uTIJc!lear the presuppositions upon which his Method rests. Method, they argue, cannot be divorced from theology, and the p11ecise writing of the form.er cannot be carried out without attention to the latter. Avery Dulles, Mauri!Oe Wiles, and Anthony Ke1ly have all leveled the charge that Method suffers from this detaichment of method from content. The purpose of this essay wiH he to discuss Lonergan's achievement in Method in Theology but then to consider the extent to which his critics may be right. Um:Lerstanding Lonergan's methodologiical enterprise requires a familiarity with his cognitionrul theory as delineated in Jnsi,ght, for his complex theory of knowing establishes the anthropology upon whiJCh he grounds his Method. Basically, he pr:obes.for ·the answers to thl"ee questions: 1) What happens when we a11e knowing? 2) Why do we cal~ that knowing? and 3) What is known when that is happening? The ans1wer to the first question yie1ds his cognitionrul theory, the second his epistemology,.and the thi11d his met:aphysics.3 Since •all knowing is a quest.for explanaition, founded upon the ass111mption of the intelligibility of the universe, the on-going search for explanation in the finite sphere implies a finail e:q>i1anation and this is be[ng itseH. In apprehending the processes of cognition, one can begin to recognize the means by which the search for·this reality is universally conducted: Thoroughly understand what it is to understand, and not only will you understand the broad lines of all that there is to be understood, but you will possess a fixed base, an invariant pattern, opening upon all further developments of understanding.4 a Lonergan, Method, p. 25. 4 Bernard Lonergan, Insight (New York, 1957), p. XVIII. Lonergan's cognitional theory draws from the work of Thomas and Kant but moves creatively beyond them in his emphasis upon the dynamism of the human mind and the nature of the reality it perceives and comes to know. For Kant, to whom Lonergan's work is often compared, the mind imposes a conceptual framework and an intelligible order upon that which it seeks to understand METHOD AND CONTENT IN THEOLOGY Lonergan's use of introspective psychology reveals four levds in human consciousness, the empir1ca1, the intellectual, the rationa1l, and the moml. The empirical ~eveJ. concentrates upon experience itself and involves the hasic questioning and intel"est in one's surroundings which all subsequent self-transcende1J1ce presupposes. It is " experiencing one's experiencing, understanding, judging and deciding." 5 Intellectual consciousness considers the elements passed on to it as " unknown " by... (shrink)

The large swinging bell Gloriosa, cast in 1497 for Erfurt Cathedral by Gherardus de Wou, ranks as an outstanding masterpiece of Gothic bell-founding art. Its musical quality and formal aesthetics became an object of emulation for generations of succeeeding bell founders and there have been repeated attempts to discover the hidden deisgn of the bell's profile. An early drawing is based on measurements made in 1865 by Sorge and consistent or modified reproductions of it were subsequently published by several authors. (...) Since 1985, a new admeasure of the bell's profile has been available. From these data a shape-fitting reconstruction was obtained by means of computer aided design (CAD) but following the traditional principles of bell design. With the aid of the finite element method (FEM) the frequencies of the partials of a bell can be calculated from its material and its profile. They make up the inner harmony as an important part of euphony, namely the purity of sound. Calculated values for the most important partials are given in terms of deviation from ideal harmonic intervals and are compared with acoustically ascertained values and modern standards. A further part of euphony, i.e. reverberation and sonority, is related to the bell metal, makingGloriosa highly resonant. As a piece of luck with a singular coincidence of perfect profile and excellent material.Gloriosa will remain the undefeatable prototype of western bells. (shrink)

Morphogenesis is a general concept in biology including all the processes which generate tissue shapes and cellular organizations in a living organism. Many hybrid formalizations have been proposed for modelling morphogenesis in embryonic or adult animals, like gastrulation. We propose first to study the ventral furrow invagination as the initial step of gastrulation, early stage of embryogenesis. We focus on the study of the connection between the apical constriction of the ventral cells and the initiation of the invagination. For that, (...) we have created a 3D biomechanical model of the embryo of the Drosophila melanogaster based on the finite element method. Each cell is modelled by an elastic hexahedron contour and is firmly attached to its neighbouring cells. A uniform initial distribution of elastic and contractile forces is applied to cells along the model. Numerical simulations show that invagination starts at ventral curved extremities of the embryo and then propagates to the ventral medial layer. Then, this observation already made in some experiments can be attributed uniquely to the specific shape of the embryo and we provide mechanical evidence to support it. Results of the simulations of the “pill-shaped” geometry of the Drosophila melanogaster embryo are compared with those of a spherical geometry corresponding to the Xenopus lævis embryo. Eventually, we propose to study the influence of cell proliferation on the end of the process of invagination represented by the closure of the ventral furrow. (shrink)

Professor Fitch carefully guides the reader through the first and second chapters demonstrating how theorems of a sentential logic are truths about so-called Q-functions. These Q-functions are given by presenting symbols for twelve basic functions, specifying that finite combinations of these basic symbols give Q-functions, and by giving rules for the introduction of basic symbols into, and the elimination of basic symbols from, combinations of these symbols. The combinators are the basic symbols which are not symbols for "and," "or," (...) "not," and "equals." Truths about Q-functions are the basic and derived introduction and elimination rules. To familiarize readers with introduction and elimination rules, he devotes an introductory chapter to a review of his method of subordinate proof which is used throughout the book. This review is also valuable for stressing the differences between his sentential logic and classical logic on one hand and intuitionistic logic on the other. Rejecting the law of excluded middle he nevertheless maintains double negation. (shrink)

The current literature that attempts to bridge between geometric morphometrics (GMM) and finite element analyses (FEA) of CT-derived data from bones of living animals and fossils appears to lack a sound biotheoretical foundation. To supply the missing rigor, the present article demonstrates a new rhetoric of quantitative inference across the GMM–FEA bridge—a rhetoric bridging form to function when both have been quantified so stringently. The suggested approach is founded on diverse standard textbook examples of the relation between forms (...) and the way strains in them are produced by stresses imposed upon them. One potentially cogent approach to the explanatory purposes driving studies of this class arises from a close scrutiny of the way in which computations in both domains, shape and strain, can be couched as minimizations of a scalar quantity. For GMM, this is ordinary Procrustes shape distance; in FEA, it is the potential energy that is stored in the deformed configuration of the solid form. A hybrid statistical method is introduced requiring that all forms be subjected to the same detailed loading designs (the same “probes”) in a manner careful to accommodate the variations of those same forms before they were stressed. The proper role of GMM is argued to be the construction of regressions for strain energy density on the largest-scale relative warps in order that biological explanations may proceed in terms of the residuals from those regressions: the local residual features of strain energy density. The method, evidently a hierarchical one, might be intuitively apprehended as a geometrical approach to a formal allometric analysis of strain. The essay closes with an exhortation. (shrink)

Model theory is concerned mainly, although not exclusively, with infinite structures. In recent years, finite structures have risen to greater prominence, both within the context of mainstream model theory, e.g., in work of Lachlan, Cherlin, Hrushovski, and others, and with the advent of finite model theory, which incorporates elements of classical model theory, combinatorics, and complexity theory. The purpose of this survey is to provide an overview of what might be called the model theory of finite structures. (...) Some topics in finite model theory have strong connections to theoretical computer science, especially descriptive complexity theory. In fact, it has been suggested that finite model theory really is, or should be, logic for computer science. These connections with computer science will, however, not be treated here.It is well-known that many classical results of ‘infinite model theory’ fail over the class of finite structures, including the compactness and completeness theorems, as well as many preservation and interpolation theorems. The failure of compactness in the finite, in particular, means that the standard proofs of many theorems are no longer valid in this context. At present, there is no known example of a classical theorem that remains true over finite structures, yet must be proved by substantially different methods. It is generally concluded that first-order logic is ‘badly behaved’ over finite structures.From the perspective of expressive power, first-order logic also behaves badly: it is both too weak and too strong. Too weak because many natural properties, such as the size of a structure being even or a graph being connected, cannot be defined by a single sentence. Too strong, because every class of finite structures with a finite signature can be defined by an infinite set of sentences. Even worse, every finite structure is defined up to isomorphism by a single sentence. In fact, it is perhaps because of this last point more than anything else that model theorists have not been very interested in finite structures. Modern model theory is concerned largely with complete first-order theories, which are completely trivial here. (shrink)

The calcium signals regulate the production and secretion of many signaling molecules like inositol trisphosphate ( $$IP_{3}$$ ) and adenosine triphosphate (ATP) in various cells including pancreatic $$\beta$$ -cells. The calcium signaling mechanisms regulating $$IP_{3}$$, ATP and insulin responsible for various functions of $$\beta$$ -cells are still not well understood. Any disturbance in these mechanisms can alter the functions of $$\beta$$ -cells leading to diabetes and metabolic disorders. Therefore, a mathematical model is proposed by incorporating the reaction-diffusion equation for calcium (...) dynamics and a system of first-order differential equations for $$IP_{3}$$, ATP-production and insulin secretion with initial and boundary conditions. The model incorporates the temporal dependence of $$IP_{3}$$ -production and degradation, ATP production and insulin secretion on calcium dynamics in a $$\beta$$ -cell. The piecewise linear finite element method has been used for the spatial dimension and the Crank-Nicolson scheme for the temporal dimension to obtain numerical results. The effect of changes in source influxes and buffers on calcium dynamics and production of $$IP_{3}$$, ATP and insulin levels in a $$\beta$$ -cell has been analyzed. It is concluded that the dysfunction of source influx and buffers can cause significant variations in calcium levels and dysregulation of $$IP_{3}$$, ATP and insulin production, which can lead to various metabolic disorders, diabetes, obesity, etc. The proposed model provides crucial information about the changes in mechanisms of calcium dynamics causing proportionate disturbances in $$IP_3$$, ATP and insulin levels in pancreatic cells, which can be helpful for devising protocols for diagnosis and treatment of various metabolic diseases. (shrink)

This recent addition to the Studies in Logic series is a systematic treatise on the set-theoretic, or semantic, approach to mathematical logic and axiomatic method. The basic notions for the discussion are those of different kinds of languages, their realizations, and the models of a formula. The book begins with a preliminary "chapter 0," giving some general theorems about classes of functions defined by finite schemas. These results are directly applicable to the language of truth-functional propositional logic, and (...) such application is accomplished in detail in chapter 1, in which interpolation, finiteness and compactness theorems are proved for propositional calculus. Chapters 2 and 3 deal with the predicate calculus without and with identity, respectively. More advanced topics dealt with in subsequent chapters include elimination of quantifiers. Certain algebraic structures such as real closed fields and some Boolean rings are given in the form of axiomatic systems in which every formula is equivalent to a quantifier-free formula. This leads to completeness. Also covered are type theory and alternate methods for developing predicate logic, the theory of definability, and the theory of principal models and infinite formulas. Appendices deal with some additional matters of philosophic interest, including a detailed discussion of set-theoretic vs. combinatorial foundations of mathematics. The book lacks an index and a bibliography, but these are not serious defects. This is a highly rewarding work.—H. P. K. (shrink)

Most science requires applied mathematics. This truism underlies the Quine-Putnam indispensability argument: we cannot be mathematical nominalists without rejecting whole swaths of good science that are seamlessly linked with mathematics. One style of response (e.g. Field’s program) accepts the challenge head-on and attempts to show how to do science without mathematics. There is some consensus that the response fails because the nominalistic apparatus deployed either is not extendible to all of mathematical physics or is merely a deft reconstrual equivalent to (...) standard mathematics. A second style of response (suggested, e.g., by Balaguer and Maddy) denies that indispensability entails realism: when we mathematize a physical problem we treat its physical content as if it were the mathematical representation; provided the two are sufficiently similar, we can use the mathematics to draw conclusions about the physics; even if we cannot represent physical facts without mathematical tools, as-if-fictionalism is reasonable. In this paper I argue that uses of mathematics in science reach deeper than is appreciated by this second response and, indeed, in the more general literature. More specifically, our confidence that we can use the mathematics to draw conclusions about the physics itself depends on mathematics. If the mathematical premises we employ in concluding that a certain application is trustworthy are false, we may lack a justification for supposing that the application will reliably lead us from correct input to correct output. For example, solutions to many physical problems require the determination of a function satisfying a differential equation. Sometimes (e.g., if the differential equation is linear) the existence of a solution for initial value problems can be established directly; where direct methods fail, the existence of a solution must be established indirectly, generally by constructing a sequence of functions that converges to a limit function that satisfies the initial value problem. Moreover, the solution often cannot be evaluated by analytic methods, and scientists must rely on finite element numerical methods to approximate the solution. Mathematical analysis of errors provides further useful information governing the choice of approximation method and of the step size and number of elements needed for the approximation to reach a desired precision. Mathematical physicists rely on the background mathematical theories (e.g., theory of differential equations) presupposed in proving the existence of the solutions and approximating them. It is difficult to see how they could do this while adding the fictionalist disclaimer, “But, you know, I don’t believe any of the mathematics I’m using”. It is difficult to see how a fictionalist pursuing the second strategy can account for the soundness of mathematical reasoning in mathematical physics and elsewhere in the sciences. The paper will fill out this argument by appeal to examples and attempt to make clear (a) how mathematics is indispensable to understanding – and thus underwriting our confidence in – applications that would otherwise be shaky approximations and idealizations and (b) how this role is difficult to square with fictionalism. (shrink)

Regarding the continuous development of high-speed trains and the increase of running speeds, the aerodynamic design of high-speed trains has become significantly important, while reduction of drag and noise comprises a significant challenge in order to optimize aerodynamic design of high-speed trains. The design form factor of a high-speed train is highly influenced by aerodynamic aspects including aerodynamic drag, lift force, and noise. With the high-speed train as the object, the paper aims to take bionic concept as the entry point, (...) selecting the hummingbird as the bionic prototype and extracting bionic elements to establish a bionic train model. Then, the finite volume method was used for numerical simulation and analysis of the aerodynamic performance and aerodynamic noise of the bionic high-speed train. Computational results prove that drag and noise of the bionic head type were lower than those of the original train; drag of the head train of the bionic model was reduced by 2.21% in comparison with the original model, while the whole-train drag was reduced by 3.53%, indicating that drag reduction effects are available and implying that the bionic head type could reduce drag and noise. Noise sources of the bionic train are mainly located at positions with easy airflow separation and violent turbulence motion. Large turbulence energy is in bogie areas and mainly exists at the leeward side of the bogie area. Obviously, the bogie area is the major noise source of the train. Aerodynamic noise of the bionic train in far-field comprises a wide-frequency range. Noises were concentrated within 613 Hz~3150 Hz. When the bionic high-speed train ran at 350 km/h, through comparative analysis of total noise levels at observed points of the high-speed train, it is found that this position with the maximum noise level was 25 m away from the head train nose tip, with the maximum value of 88.4 dB. When the bionic train ran at 600 km/h, the maximum sound pressure level at the longitudinal point was 99.7 dB and the average noise level was 96.6 dB. When the running speed increased from 350 km/h to 600 km/h, the maximum noise level increased by 11.3 dB and the average noise level increased by 11.6 dB. Computation results of aerodynamic noise at the point which is 7.5 m away from the rail center show that the maximum aerodynamic noise level existed at the first-end bogie of the head train, while the noise level was larger at the position closer to the ground. (shrink)

Insufficient stiffness of industrial robots is a significant factor which affects its positioning accuracy. To improve the positioning accuracy, a novel positioning error compensation method based on the stiffness modelling is proposed in this paper. First, the positioning errors considering the end load and gravity of industrial robots due to stiffness are analyzed. Based on the results of analysis, it is found that the positioning errors can be described by two kinds of deformation errors at joints: the axial deformation (...) error and the radial deformation error. Then, the axial deformation error is modelled by the differential relationship of kinematics equations. The model of radial deformation error is deduced through the recurrence method and rotation transformation between joints. Finally, these two models are transformed into a Cartesian coordinate system, and a positioning error compensation method based on these two models is presented. Simulations based on the finite element analysis are implemented to verify the positioning error compensation method. The results show that the suggested method can efficiently predict the positioning error according to the gravity and loads, so that the positioning accuracy of industrial robots can be improved with the proposed method. (shrink)

The objective of the current study was to propose a sensitivity analysis of a 3D left ventricle model in order to assess the influence of parameters on myocardial mechanical dispersion. A finite element model of LV electro-mechanical activity was proposed and a screening method was used to evaluate the sensitivity of model parameters on the standard deviation of time to peak strain. Results highlight the importance of propagation parameters associated with septal and lateral segments activation. Simulated curves (...) were compared to myocardial strains, obtained from echocardiography of one healthy subject and one patient diagnosed with intraventricular dyssynchrony and coronary artery disease. Results show a close match between simulation and clinical strains and illustrate the model ability to reproduce myocardial strains in the context of intraventricular dyssynchrony. (shrink)

This work deals with the context of formation of Professor Dr. John Hadji Argyris in Germany during the 1930s and Switzerland during the 1940s. Using primary documentation, we elucidate publications with scientific theories of structural analysis made during his job as a member of a secret Commission in the Royal Aeronautical Society, in England. We explore the content of the serial publication of the Theorems of Energy and Structural Analysis of the Aircraft Engineering Journal, from 1954 and 1955, from Argyris’s (...) lectures at Imperial College, London, where he was a professor and director of the Department of Aeronautical Structures. The goal of this research is to analyze the systematic method of calculation of Argyris, starting from the theory of Computational Simulation. From this point of view, the conceptual mathematical model would be a computational model based on the unification of the concepts of Elasticity Theory and Energy Theorems formulated in matrix mathematics for communication with the computer. (shrink)