Structure Of Mathematical Model Research Articles

DETERMINATION NATURAL VIBRATIONS OF THE CONTINUED PLACED ON CURVE FLYOVER IN OPERATION

Purpose. The study of the dynamic behavior, the definition of shapes and natural frequencies of the bridge structure, which were designed and built at a time when the dynamic calculation of complex structures carried by simplifying the design schemes. Methodology. To obtain accurate dynamic characteristics of the structure under the action of wheeled vehicles on the bridge crossing, it was decided to use the calculation method of mathematical modeling of structures, namely finite element method. Simulation and calculation of this structure was carried out in an environment of « Lira." Drafted model meets all geometric and linear characteristics of the real structure, which is confirmed by the results obtained and the values obtained in the tests that were conducted BSRL of Dynamics bridges. Findings. On the basis of the calculations it follows that all forms of free oscillations of the overpass are mutually connected with each other and thus share the eigen modes of structures on vertical, horizontal and torsionalonly conditionally. Accepted scheme of the finite element model flyover solves problems related not only to the dynamic characteristics, but also to determine the actual values of internal forces ( normal , transverse moments) in any given structural member when subjected to a single fixed force or group of forces. Originality. As is known, the current trends of domestic and foreign bridge construction associated with the widespread introduction of new highstrength materials, the improvement of the design and technological forms and methods of calculation. Changes these factors in structures resulted in a reduction of rigidity , increased sensitivity to their dynamic effects. In this regard (as well as the intensity and magnitude of load) increased the role of dynamic calculations, studies the dynamic behavior of the bridge structure. Practical value. Based on the results of mathematical modeling ofatypical superstructure of the bridge, it can be argued that the use of the finite element method is an effective way to determine the dynamic characteristics. Also positive difference of this method from others is the ability to visualize the results, allowing you to identify the characteristic features in the building.

Использование математической модели структуры древесноволокнистых плит средней плотности для обоснования режимов их обработки

Использование математической модели структуры древесноволокнистых плит средней плотности для обоснования режимов их обработки

ABAQUS-Based Numerical Computation and Experiment Research on Silicon Rubber Mould’s Deformation during DPVC Process

Aiming at exploiting the impact of filling rate and pressure difference on thin-wall product during filling stage of differential pressure vacuum casting (DPVC) process and based on Yeoh model, a finite element mathematical structure model of silicon rubber is proposed. Employing nonlinear Finite Element Method (FEM), the impact of soft moulds deformation on products dimensional precision during different pressure difference is studied. Finally, the experiment carried out on a sample machine verifies that the solution of established finite element mathematical structure model of silicon rubber is very close to experiment result and thus provides an effective method for optimizing the pressure difference and mould optimized design.

Category Theory and Model-Driven Engineering: From Formal Semantics to Design Patterns and Beyond

There is a hidden intrigue in the title. CT is one of the most abstract mathematical disciplines, sometimes nicknamed "abstract nonsense". MDE is a recent trend in software development, industrially supported by standards, tools, and the status of a new "silver bullet". Surprisingly, categorical patterns turn out to be directly applicable to mathematical modeling of structures appearing in everyday MDE practice. Model merging, transformation, synchronization, and other important model management scenarios can be seen as executions of categorical specifications. Moreover, the paper aims to elucidate a claim that relationships between CT and MDE are more complex and richer than is normally assumed for "applied mathematics". CT provides a toolbox of design patterns and structural principles of real practical value for MDE. We will present examples of how an elementary categorical arrangement of a model management scenario reveals deficiencies in the architecture of modern tools automating the scenario.

COMPARISON OF EFFECTIVENESS OF ADAPTIVE NEURO‐FUZZY INFERENCE SYSTEM AND ARTIFICIAL NEURAL NETWORKS FOR ESTIMATION OF LINEAR CREEP AND RECOVERY PROPERTIES OF MODEL MEAT EMULSIONS

ABSTRACTIn meat emulsion systems, it is impossible to interpret the results from the molecular perspective due to their complexity. Therefore, it is very difficult to perform mathematical modeling of structure of the emulsion systems due to their ill‐defined viscoelastic (creep and recovery) nature. Therefore, an adaptive neuro‐fuzzy inference system (ANFIS) was used to accurately model the effect of creep test time, temperature and oil levels on the compliance (J), creep and recovery phase parameters. In this respect, ANFIS with different types of input membership functions (MFs) was developed. MF “trimf” performed better than others. The ANFIS model was compared with artificial neural network (ANN) and multiple linear regression (MLR) models. The estimation by ANFIS was superior to those obtained by ANN and MLR models. The ANFIS model resulted in a good fit with the observed data, especially for the creep phase data in the checking period.PRACTICAL APPLICATIONSIn literature, no study has appeared to model the effect of creep test time, temperature and oil levels on the compliance (J), creep and recovery phase parameters of O/W model system meat emulsions using adaptive neuro‐fuzzy inference system (ANFIS), artificial neural network and multiple linear regression techniques. In this study, the ANFIS model resulted in a good fit with the observed data, indicating that the creep and recovery properties of the O/W model system meat emulsions can be estimated using the ANFIS model. As a result, among the models used, ANFIS was found to be the best model that can be efficiently used to estimate unmeasured or untested interval values of creep and recovery properties. This might be quite significant for meat industry that will benefit from estimating texture of such products previously before producing them at a large scale, thus enabling them to save time.

The equations of motion of the main structure with attached multiple tuned mass dampers

A mathematical model of structure with multiple tuned mass dampers (MTMD) is presented in this paper. An important difficulty, connected with these model, is building a global damping matrix of the system. The own proposals FEM elements describing additional elements attached to the main system in the form of tuned dampers have been proposed here. The benefits of the new FEM elements have been briefly discussed.

The equations of motion of the main structure with attached dampers described by standard rheological model

A mathematical model of structure with multiple tuned mass dampers (MTMD) is presented in this paper. An important difficulty, connected with these model, is building a global damping matrix of the system. The own proposals of FEM elements describing additional elements attached to the main system in the form of tuned dampers are presented here. The benefits of the new FEM elements are briefly discussed.

Modeling of structure?property relationships for hydrocarbons involving the basis topological descriptors

The article concerns the problem of selection of topological molecular descriptors to be used in constructing mathematical models of structure—property relationships for hydrocarbons. A new method of solving this problem is proposed. The approach involves construction of parameter-dependent basis topological descriptors and selection of the descriptors suitable for constructing particular models. A qualitative substantiation of the method proposed is given and some examples of its application to modeling of the structure—property relationships for hydrocarbons are presented.

Mathematical structure model for Word-Based Program

The new software world is progressing steadily forward but is not yet within range of where it needs to be. This paper presents a mathematical ground for the Lyee methodology, which has already produced several achievements in industry. This method enables us not to attention the sequential order of program execution. By introducing the concept of a state, it is possible to prove the program structure. The construction of such a program structure allows programmers to focus on conditions and formulae that calculate the value. Through this model, a system divided for catching correct requirements quickly is integrated, and its optimal program with minimum repetitions can be generated by rearranging words into the right order.

Active vibration control of a structure with output feedback based on simultaneous optimization design method

Recent advances in the field of control theory have enabled us to design active vibration control systems for various structures. In many studies, the controller used to suppress vibration has been synthesized for the given mathematical model of structure. In these cases, the designer has not been able to utilize the degree of freedom to adjust the structural parameters of the control object. To overcome this problem, so called “Structure/ Control Simultaneous Optimization Method” is used. In this context of view, this paper is concerned with the active vibration control of bridge towers, platforms and ocean vehicles etc. Simultaneous design method is used to achieve optimal system performance. Here, a general framework for the simultaneous design problem of output feedback case is introduced based on LMI (Linear Matrix Inequality). The simulation results show that the proposed design method achieves desirable control performance.

Modeling Project Performance for Decision Making

This paper presents a performance modeling methodology for application to individual projects. The model combines experience captured from experts with assessments from the project team. The methodology consists of a conceptual, qualitative-model structure and a mathematical-model structure. The conceptual-model structure, called the general performance model (GPM), is a simplified model of the variables and interaction that influence project performance. The mathematical model uses concepts of cross-impact analysis and probabilistic inference to capture the uncertainties and interactions among project variables. The GPM allows management to test different combinations of project-execution options and predict expected cost, schedule, and other performance impacts. The methodology provides a systematic and structured process for a project-team discussion on relevant planning issues in a project. Researchers should benefit from the exploratory and analytical capabilities of the methodology, as well as the flexible knowledge structure to update models and data. Computer implementation is also attractive as a means to disseminating research results.

Properties of various residuals within updating of mathematical models

A general synthesis is proposed of the properties of different types of residual functions used in the para-metric updating of mathematical models for structures in linear elastodynamics. This synthesis concerns fundamental aspects such as: parametrization by submodels, residuals properties, statistically based weighting and measurement sensitivity. Special aspects are also envoked such as the localization of dominant modeling errors and the properties of the Hessian matrix of the cost function. Numerous references concerning these different aspects are provided and recommendations concerning delicate points in parametric correction are proposed.

Modeling RNA secondary structures I. Mathematical structural model for predicting RNA secondary structures

A mathematical model for analyzing the secondary structures of RNA is developed that is based on the connection matrix associated with the planar p-h graph. The classification of the elementary structures allows the introduction of the basis of structural space from which to build the global secondary structure. All admissible solutions belong to the configuration space and can be obtained directly from its basis.

A mathematical structural model of clinical competency in emergency medicine: Results across ten years of studies : Huang, RR, Maatsch, J.L., Munger, B, Office of Medical Education Research and Development, College of Human Medicine, Michigan State University, The American Board of Emergency Medicine, E. Lansing, Michigan, USA

A mathematical structural model of clinical competency in emergency medicine: Results across ten years of studies : Huang, RR, Maatsch, J.L., Munger, B, Office of Medical Education Research and Development, College of Human Medicine, Michigan State University, The American Board of Emergency Medicine, E. Lansing, Michigan, USA

The Harmonic Oscillator with Random Stiffness

ABSTRACT A harmonic oscillator with time dependent random stiffness is considered. Since there is no exact solution in the case of colored noise random stiffness, approximate techniques must be used. The goal of this paper is to investigate an iterative procedure. The quality of this approximation, when compared to the exact solution, is established using a Monte Carlo simulation. In order to model a stiffness with positive values only, it is assumed that it has a doubly truncated Gaussian distribution. After a brief review of the iterative method and an outline of the design of the Monte Carlo simulation, an extensive parametric study is presented to establish ranges of parameter values for which the derived approximation is valid. This comparison study leads to a design criterion for mathematical modeling of structures with parametric uncertainties.

Computer-controlled manipulator system for autonomous inspection

The paper describes research carried out in the Mechanical Engineering Department at University College London with the aim of investigating the feasibility of introducing automation into remote structural inspection. The work concentrates on the problems associated with building up a mathematical model of structures made from cylindrical components by gathering tactile information using a computer-controlled manipulator. The results are of particular relevance to the inspection of offshore structures, pipelines, and nuclear plants. Experiments have been carried out in the laboratory, both using a three-degrees-of-freedom electrohydraulic manipulator fitted with a tactile sensor and by using a graphical simulation of a similar manipulator with enhanced capabilities. The paper describes the development of the hardware and software that was needed to carry out the experiments and discusses several methods of using tactile data to deduce the shape and size of cylinders. The experiments that were carried out are described and the results of sensitivity studies into the effects of measurement noise are presented. Finally, the main achievements of the research are summarised and possible extensions to the work are discussed

Mathematical modeling of complex structures for dynamic analysis

The development of mathematical models of structural analysis requires not only knowledge of the principles of structural theory, but also practical experience. This is particularly true if the response to dynamic loads is to be analyzed. This paper summarizes a number of techniques which the authors have found useful for the purpose of developing and verifying mathematical models for complex structures encountered in engineering practice. Examples chosen from the dynamic analysis of machinery equipment of a modern ship are included to illustrate some of these techniques.

A perspective on system theory

In broad terms "system theory" is concerned with the analytical and computational aspects of mathematical models of structures comprised of subsystems or components. This paper contains a section on the origins and history of system theory, and additional sections concerning: (i) nonlinear networks containing semiconductor devices, (ii) functional-analytic methods and the circle criterion, (iii) compartmental analysis and input-output models of a national economy, and (iv) functional expansions and Volterra series. The first section provides a broad view of system theory, with emphasis on its early development; the remaining sections illustrate in more detail the nature of some general problems and results of interest to this writer and others.

The simulation of natural phenomena (Panel Session)

This panel will discuss the issues and the problems associated with the simulation of natural phenomena. This is a difficult area of research since it generally involves complex data bases and in many instances time variant phenomena. The computational loads can become enormous as one considers the physics or the mathematical modeling of structures. Most items in nature, trees, clouds, fire and comets being some examples, have not been displayed realistically in computer graphics. This lack stems from a few different problems, all of which are significant. The first is the fact that realistic portrayals require large amounts of storage and consequently large compute time. Nature is able to create diverse detail at the most minute levels within an object of grandoise scale. The second problem is that of diversity of design within a given framework. For example, if a scene requires two dozen poplar trees, how does the designer construct trees that look different but are undeniably poplars? Humans typically become tired after the first few iterations of such a design process, with a resulting degradation in the subsequent models. Clearly, this problem applies to all of the phenomena mentioned above. Finally, there is a lack of models. First, second and third order representations are commonly used in computer graphics to model various kinds of surfaces and their boolean combinations. However, their applications to objects, which do not lend themselves well to being described as surfaces has not been addressed sufficiently. Previous attempts at realism have dealt with the appearances of the surfaces being modeled, in terms of their illumination or relief. More recently, fractal methods have introduced a new degree of realism into terrain modeling systems. However, it appears that natural phenomena will require more research into the fundamental way things occur in nature, and in terms of computer graphics, their representation will build on previous work, but will still require new modeling techniques.

A simple method for designing structural models with closely spaced modes of vibration

Vehicle structures often have closely spaced modes of vibration within the frequency spectrum of applied loads. Such modes are important since they tend to be the source of vibration problems. In order to study the effects that closely spaced modes have on structural response in such situations as modal testing and self-excited vibrations, it is useful to be able to design a mathematical structural model having closely spaced modes. In this paper, a method for designing such a model is presented and illustrated with examples. Given a reference model with specified geometry and degrees of freedom, the lumped inertias and stiffnesses of the model are perturbed in such a manner as to force together two of its natural frequencies. With a slight alteration, the method is also applicable to the inverse problem of separating undesirable closely spaced modes which appear in a structural design.