scholarly journals An Alternate View of Dimensional Homogeneity, and Its Impact on Engineering Science

2018 ◽  
Vol 12 (1) ◽  
pp. 164-174
Author(s):  
Eugene F. Adiutori
Keyword(s):  
Nonlinear Problems ◽  
Engineering Science ◽  
Relative Simplicity ◽  
Conventional View ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Dimensional Homogeneity

Aims:This article proposes an alternate view of dimensional homogeneity that greatly simplifies the solution of nonlinear engineering problems.Background:The conventional view of dimensional homogeneity is generally credited to Fourier (1822).Objectives:The objectives of this article are to describe the alternate view of dimensional homogeneity and to demonstrate its application to practical engineering problems.Methods:By presenting the solution of several nonlinear engineering problems, this article compares solutions based on the alternate view of dimensional homogeneity with solutions based on the conventional view.Results:Example problems demonstrate that nonlinear engineering problems are much easier to solve if the solutions are based on the alternate view of dimensional homogeneity rather than the conventional view. The relative simplicity results because the alternate view of dimensional homogeneity reduces the number of variables in nonlinear problems.Conclusion:The widely accepted view of dimensional homogeneity should be replaced by the alternate view because the solution of nonlinear engineering problems is greatly simplified.

scholarly journals Why conventional engineering science should be abandoned, and the new engineering science that should replace it

2020 ◽  
Author(s):  
EUGENE ADIUTORI
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Nonlinear Problems ◽  
Nonlinear Phenomena ◽  
Engineering Science ◽  
Conventional View ◽  
Linear And Nonlinear

Conventional engineering science should be abandoned because: Engineering laws that are proportional equations (such as q = hT) cannot describe nonlinear phenomena (such as boiling heat transfer). Engineering laws were created by assigning dimensions to numbers, in violation of the conventional view that dimensions must not be assigned to numbers. Contrived parameters (such as heat transfer coefficient) make it impossible to solve nonlinear problems with the variables separated, greatly complicating solutions. All engineering equations are irrational because they attempt to describe how the numerical values and dimensions of parameters are related, when in fact equations can rationally describe only how numerical values are related. In the new engineering science described herein: Engineering laws do describe proportional, linear, and nonlinear phenomena. No engineering laws were created by assigning dimensions to numbers. There are no contrived parameters (such as heat transfer coefficient), and therefore nonlinear problems are solved with the variables separated. All engineering equations are rational because they describe only how the numerical values of parameters are related.

Structural similitudes of stiffened cylinders

2017 ◽  
Vol 24 (3) ◽  
pp. 527-541 ◽  
Author(s):  
G Petrone ◽  
M Manfredonia ◽  
S De Rosa ◽  
F Franco
Keyword(s):  
Numerical Simulation ◽  
Structural Engineering ◽  
Scaling Laws ◽  
Similarity Theory ◽  
Design Tool ◽  
Engineering Science ◽  
The Finite Element Method ◽  
Engineering Problems ◽  
Incomplete Similarity ◽  
Scaled Models

Similarity theory is a branch of engineering science that deals with establishing conditions of similarity among phenomena and is applied to various fields, such as structural engineering problems, vibration and impact. Tests and numerical simulation of scaled models are still a valuable design tool, whose purpose is to accurately predict the behaviour of large or small prototypes through scaling laws applied to the experimental and numerical results. The aim of this paper is to predict the behaviour of the complete and incomplete similarity of stiffened cylinders by applying distorted scaling laws of the models in similitude. The investigation is performed using models based on the finite element method within commercial software. Two classes of cylinders scaled, with different laws, and, hence, reproducing replicas (exact similitude) and avatars (distorted similitude) are investigated.

scholarly journals Reflections on the Hysteretic Damping Model

2009 ◽  
Vol 16 (5) ◽  
pp. 529-542 ◽  
Author(s):  
Nuno Maia
Keyword(s):  
Free Vibration ◽  
Point Of View ◽  
The Other ◽  
Hysteretic Damping ◽  
Engineering Problems ◽  
Practical Engineering ◽  
The Subject ◽  
The One ◽  
Damping Model ◽  
Free Vibration Response

This paper presents a reflection on a recently proposed solution to the problem of the free vibration response with the constant hysteretic damping model, that has been presented in some conferences in recent years, by the author himself and some of his colleagues. On the one hand, as expected, the subject has been received with natural criticism, mainly due to the well-known non-causal behaviour of the model in free vibration. On the other hand, it was not easy to understand what could be wrong in that proposal, as apparently everything was perfect from a mathematical point of view. The author decided that this subject deserved a more careful and detailed analysis and – in this kind of tutorial paper – the issue seems to have been clarified. It is concluded that the proposed solution involving the constant hysteretic damping corresponds in fact to an equivalent viscously damped model; it is therefore concluded that the application of the constant hysteretic damping to model the free vibration of practical engineering problems should be considered only in the perspective of an equivalent viscously damped model.

An integrated surrogate modeling method for fusing noisy and noise-free data

2021 ◽  
pp. 1-23
Author(s):  
Kunpeng Li ◽  
Shuo Wang ◽  
Yin Liu ◽  
Xueguan Song
Keyword(s):  
Data Fusion ◽  
Noisy Data ◽  
Proposed Model ◽  
Free Data ◽  
Multiple Surrogate Models ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Key Issues ◽  
Type Data ◽  
Underlying Trend

Abstract Datasets in engineering applications often contain multiple types of data, i.e., noise-free data, noisy data with known noise variances, and noisy data with unknown noise variances. In this paper, a data fusion method, termed as multi-type data fusion (MTDF) model, is proposed to fully utilize the information provided by each of these types of data. The proposed model strives to capture the underlying trend implied in the multiple types of data better by approximately interpolating the noise-free data while regressing with the noisy data. To evaluate the prediction accuracy of the MTDF model, it is compared with multiple surrogate models including interpolation models, regression models, and multi-fidelity models on both numerical and practical engineering problems. The results show that the proposed MTDF model presents a more outstanding performance than the other benchmark models. The key issues, i.e., the effect of noise level, the effect of the sample size of noise-free data, and the robustness of the MTDF model are also investigated. The results illustrate that the MTDF model possesses satisfactory feasibility, practicality, and stability.

scholarly journals Performance Evaluation of MDO Architectures within a Variable Complexity Problem

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Daiyu Zhang ◽  
Baowei Song ◽  
Peng Wang ◽  
Yanru He
Keyword(s):  
Performance Evaluation ◽  
Multidisciplinary Design Optimization ◽  
Large Scale ◽  
Multidisciplinary Design ◽  
Design Variables ◽  
Complexity Problem ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Coupling Variables ◽  
Selection Of

Though quite a number of multidisciplinary design optimization (MDO) architectures have been proposed for the optimal design of large-scale multidisciplinary systems, how their performance changes with the complexity of MDO problem varied is not well studied. In order to solve this problem, this paper presents a variable complexity problem which allows people to obtain a MDO problem with arbitrary complexity by specifying its changeable parameters, such as the number of disciplines and the numbers of design variables. Then four investigations are performed to evaluate how the performance of different MDO architectures changes with the number of disciplines, global variables, local variables, and coupling variables varied, respectively. Finally, the results supply guidance for the selection of MDO architectures in solving practical engineering problems with different complexity.

scholarly journals An Efficient Hybrid Algorithm for Multiobjective Optimization Problems with Upper and Lower Bounds in Engineering

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Guang Yang ◽  
Tao Xu ◽  
Xiang Li ◽  
Haohua Xiu ◽  
Tianshuang Xu
Keyword(s):  
Multiobjective Optimization ◽  
Lower Bounds ◽  
Hybrid Algorithm ◽  
High Efficiency ◽  
Optimization Problems ◽  
Simultaneous Optimization ◽  
Upper And Lower Bounds ◽  
Optimization Models ◽  
Engineering Problems ◽  
Practical Engineering

Generally, the inconvenience of establishing the mathematical optimization models directly and the conflicts of preventing simultaneous optimization among several objectives lead to the difficulty of obtaining the optimal solution of a practical engineering problem with several objectives. So in this paper, a generate-first-choose-later method is proposed to solve the multiobjective engineering optimization problems, which can set the number of Pareto solutions and optimize repeatedly until the satisfactory results are obtained. Based on Frisch’s method, Newton method, and weighed sum method, an efficient hybrid algorithm for multiobjective optimization models with upper and lower bounds and inequality constraints has been proposed, which is especially suitable for the practical engineering problems based on surrogate models. The generate-first-choose-later method with this hybrid algorithm can calculate the Pareto optimal set, show the Pareto front, and provide multiple designs for multiobjective engineering problems fast and accurately. Numerical examples demonstrate the effectiveness and high efficiency of the hybrid algorithm. In order to prove that the generate-first-choose-later method is rapid and suitable for solving practical engineering problems, an optimization problem for crash box of vehicle has been handled well.

Finite-element analysis of axi-symmetric rotors

1969 ◽  
Vol 4 (3) ◽  
pp. 163-168
Author(s):  
H Stordahl ◽  
H Christensen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Engineering Problems ◽  
Symmetric Rotor ◽  
Practical Engineering ◽  
Element Method

The finite-element method (1) (2)∗ is increasingly used in the stress analysis of mechanical-engineering problems. It is the purpose of this paper to described how the finite-element method can be used as an effective tool in the design of rotors. Up to the present time this method has mainly been used in the analysis of two-dimensional problems. However, a special class of three-dimensional problems, namely axi-symmetric rotors, can be treated as a nearly two-dimensional problem. This paper summarizes the development of the finite-element method as applied to the analysis of the axi-symmetric rotor. A computer programme is then briefly described, and the application of the method to the solution of three examples taken from practical engineering experience are presented.

MESHFREE METHODS AND THEIR COMPARISONS

2005 ◽  
Vol 02 (04) ◽  
pp. 477-515 ◽  
Author(s):  
Y. T. GU
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Future Development ◽  
Meshless Method ◽  
Meshfree Methods ◽  
Shape Functions ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Technical Issues

In recent years, one of the hottest topics in computational mechanics is the meshfree or meshless method. Increasing number of researchers are devoting themselves to the research of the meshfree methods, and a group of meshfree methods have been proposed and used to solve the ordinary differential equations (ODEs) or the partial differential equations (PDE). In the meantime, meshfree methods are being applied to a growing number of practical engineering problems. In this paper, a detailed discussion will be provided on the development of meshfree methods. First, categories of meshfree methods are introduced. Second, the methods for constructing meshfree shape functions are discussed, and the interpolation qualities of them are also studied using the surface fitting. Third, several typical meshfree methods are introduced and compared with each others in terms of their accuracy, convergence and effectivity. Finally, the major technical issues in meshfree methods are discussed, and the future development of meshfree methods is addressed.

scholarly journals An Efficient Reliability Analysis Method Combining Improved EIF Active Learning Mechanism and Kriging Metamodel

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Dawei Zhang ◽  
Xiaohua Wu ◽  
Weilin Li ◽  
Xiaofeng Lv
Keyword(s):  
Active Learning ◽  
Reliability Analysis ◽  
Kriging Model ◽  
Expected Improvement ◽  
Learning Mechanisms ◽  
Learning Mechanism ◽  
Engineering Problems ◽  
Real Performance ◽  
Practical Engineering ◽  
Expected Improvement Function

Complex implicit performance functions widely exist in many engineering problems. The reliability analysis of these problems has always been a challenge. Using surrogate model instead of real performance function is one of the methods to solve this kind of problem. Kriging is one of the surrogate models with precise interpolation technique. In order to make the kriging model achieve higher accuracy using a small number of samples, i.e., improve its practicability and feasibility in practical engineering problems, some active learning equations are wildly studied. Expected improvement function (EIF) is one of them. However, the EIF has a great disadvantage in selecting the added sample point. Therefore, a joint active learning mechanism, J-EIF, is proposed to obtain the ideal added point. The J-EIF active learning mechanism combines the two active learning mechanisms and makes full use of the characters of kriging model. It overcomes the shortcoming of EIF active learning mechanism in the selection of added sample points. Then, using Monte Carlo Simulation (MCS) results as a reference, the reliability of two examples is estimated. The results are discussed showing that the learning efficiency and accuracy of the improved EIF are both higher than those of the traditional EIF.

Sign in / Sign up

Export Citation Format

Share Document