Bifurcation Control and Complex Dynamics in Field-Oriented Control of a PMSM

2019 ◽  
Vol 28 (04) ◽  
pp. 1930004 ◽  
Author(s):  
W. Souhail ◽  
H. Khammari ◽  
M. F. Mimouni
Keyword(s):  
Complex Dynamics ◽  
Sufficient Conditions ◽  
General Purpose ◽  
Parameter Plane ◽  
Field Oriented Control ◽  
Parametric Space ◽  
Starting Point ◽  
Bifurcation Surface ◽  
Bifurcation Structures ◽  
Two Parameters

The general purpose of this paper is to develop new aspects of bifurcation structures in a 3D parametric space. Identification of generic bifurcation structures in former studies was based on the arrangement of bifurcation curves in the parameter plane. So by analogy to such studies, we define the bifurcation surface in 3D parameter space as the main feature of the said generic structures. The implementation of this idea is made on the permanent magnet synchronous machine (PMSM) whose speed is regulated with a field-oriented control (FOC). Sufficient conditions are given for the existence of three main bifurcations: limit point (LP), Hopf (H) and Bogdanov–Takens (BT). Starting from bifurcation curves traced in a parameter plane and changing a third parameter, a qualitative bifurcation surface is constructed in a 3D parametric space. This led to underline the increasing complexity of the bifurcation structures when dealing with more than two parameters. This study put into evidence not only the complex behavior of PMSM, but stands as a starting point for a new formalism on the bifurcation structures in a 3D parametric space.

A MODIFIED GENERALIZED LORENZ-TYPE SYSTEM AND ITS CANONICAL FORM

2009 ◽  
Vol 19 (06) ◽  
pp. 1931-1949 ◽  
Author(s):  
QIGUI YANG ◽  
KANGMING ZHANG ◽  
GUANRONG CHEN
Keyword(s):  
Special Form ◽  
Topological Structure ◽  
Complex Dynamics ◽  
Type System ◽  
Chaotic Attractors ◽  
Hopf Bifurcations ◽  
Compound Structure ◽  
Two Parameters ◽  
First Time ◽  
New System

In this paper, a modified generalized Lorenz-type system is introduced, which is state-equivalent to a simple and special form, and is parameterized by two parameters useful for chaos turning and system classification. More importantly, based on the parameterized form, two classes of new chaotic attractors are found for the first time in the literature, which are similar but nonequivalent in topological structure. To further understand the complex dynamics of the new system, some basic properties such as Lyapunov exponents, Hopf bifurcations and compound structure of the attractors are analyzed and demonstrated with careful numerical simulations.

scholarly journals DEVELOPMENT OF CHINESE-KAZAKHSTAN TRADE IN AGRICULTURAL PRODUCTS WITHIN THE FRAMEWORK OF "ONE BELT, ONE WAY": FEATURES, FORMS OF COOPERATION AND PERSPECTIVES

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Haohe Zhang
Keyword(s):  
Bilateral Trade ◽  
Complex Dynamics ◽  
Economic Cooperation ◽  
Agricultural Trade ◽  
Agricultural Products ◽  
Trade Barriers ◽  
Starting Point ◽  
Trade Turnover ◽  
Belt And Road ◽  
Bilateral Cooperation

The "Оne Вelt, Оne Road" policy has brоught ecоnоmic and trаde relаtiоns between Chinа аnd Kаzаkhstаn closer in the field of agricultural products, adding new opportunities for development, and the volume of tradе has bеcomе stаblе and grоwing. Bilateral trade between China and Kazakhstan has shown new positive dynamics, where a unified trade structure is also noted. There are great development prospеcts in the field of agricultural products of the two countries. In this regard, the author points to a mega-project called the Belt and Road Initiative, which focuses on the current situation and characteristics of Sino-Kazakh agricultural trade. The article indicates some problems in the bilateral cooperation of the two states. Among these problems, the most important are noted. For example, the author notes that the situation with a large number of trade barriers prevents more Chinese and Kazakh enterprises from entering the market. As a starting point based on an analysis of the obstacles facing the development of bilateral agricultural trade, countermeasures should be taken to further deepen bilateral cooperation in agricultural trade. A set of proposals to mitigate the problems of economic cooperation between Kazakhstan and China are offered in the conclusion of the article. Key words: trade and economic cooperation, agrarian complex, dynamics of agricultural production growth, trade volume, trade turnover, trade barriers, RK, PRC.

scholarly journals A Novel Convolutional Neural Network for Classifying Indian Coins by Denomination

2021 ◽  
Author(s):  
Yash Chauhan ◽  
Prateek Singh
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Academic Research ◽  
High Volume ◽  
Classification Problem ◽  
General Purpose ◽  
Training Data ◽  
Slot Machines ◽  
Validation Data ◽  
Starting Point

Coins recognition systems have humungous applications from vending and slot machines to banking and management firms which directly translate to a high volume of research regarding the development of methods for such classification. In recent years, academic research has shifted towards a computer vision approach for sorting coins due to the advancement in the field of deep learning. However, most of the documented work utilizes what is known as ‘Transfer Learning’ in which we reuse a pre-trained model of a fixed architecture as a starting point for our training. While such an approach saves us a lot of time and effort, the generic nature of the pre-trained model can often become a bottleneck for performance on a specialized problem such as coin classification. This study develops a convolutional neural network (CNN) model from scratch and tests it against a widely-used general-purpose architecture known as Googlenet. We have shown in this study by comparing the performance of our model with that of Googlenet (documented in various previous studies) that a more straightforward and specialized architecture is more optimal than a more complex general architecture for the coin classification problem. The model developed in this study is trained and tested on 720 and 180 images of Indian coins of different denominations, respectively. The final accuracy gained by the model is 91.62% on the training data, while the accuracy is 90.55% on the validation data.

Educational Technoethics Applied to Career Guidance

2011 ◽  
pp. 175-188
Author(s):  
Manjit Singh Sidhu ◽  
Pilar Alejandra Cortés Pascual
Keyword(s):  
Professional Development ◽  
Career Guidance ◽  
Historical Context ◽  
Ethical Analysis ◽  
Ethical Values ◽  
Professional Orientation ◽  
Starting Point ◽  
Points Of View ◽  
Two Parameters ◽  
Present Text

Educational orientation should be set within a specific socio-historical context, which is nowadays characterized by the Society of Information. From this starting point, we think that the understanding of both an ethical analysis of technology as well as of the means of communication, which individuals will have to deal with in their professional development, must be considered as content linked to professional orientation. This idea becomes more definite in the concept of educational technoethics and it is studied from two parameters: the intrinsic values that technology and the means of communication include (the aim of technoethics) and their use as mediators of ethical values (means of technoethics). Therefore, the proposal that is currently being implemented in the project “Observation Laboratory on Technoethics for Adults” (LOTA) as well as its implications for professional orientation are concisely presented from both points of view. The present text is a review and update of a previously published article (Cortés, 2006).1

scholarly journals Complex Canard Explosion in a Fractional-Order FitzHugh–Nagumo Model

2019 ◽  
Vol 29 (08) ◽  
pp. 1950111 ◽  
Author(s):  
Mohammed-Salah Abdelouahab ◽  
René Lozi ◽  
Guanrong Chen
Keyword(s):  
Dynamical System ◽  
Fractional Order ◽  
Complex Dynamics ◽  
Search Algorithm ◽  
Two Dimensional ◽  
Mixed Mode Oscillations ◽  
The Stability ◽  
Two Parameters ◽  
Complex Phenomena ◽  
Autonomous Dynamical System

This article investigates the complex phenomena of canard explosion with mixed-mode oscillations, observed from a fractional-order FitzHugh–Nagumo (FFHN) model. To rigorously analyze the dynamics of the FFHN model, a new mathematical notion, referred to as Hopf-like bifurcation (HLB), is introduced. HLB provides a precise definition for the change between a fixed point and an [Formula: see text]-asymptotically [Formula: see text]-periodic solution of the fractional-order dynamical system, as well as the stability of the FFHN model and the appearance of the HLB. The existence of canard oscillations in the neighborhoods of such HLB points are numerically investigated. Using a new algorithm, referred to as the global-local canard explosion search algorithm, the appearance of various patterns of solutions is revealed, with an increasing number of small-amplitude oscillations when two key parameters of the FFHN model are varied. The numbers of such oscillations versus the two parameters, respectively, are perfectly fitted using exponential functions. Finally, it is conjectured that chaos could occur in a two-dimensional fractional-order autonomous dynamical system, with the fractional order close to one. After all, the article demonstrates that the FFHN model is a very simple two-dimensional model with an incredible ability to present the complex dynamics of neurons.

AUTO-TUNING PARALLEL SKELETONS

2012 ◽  
Vol 22 (02) ◽  
pp. 1240005 ◽  
Author(s):  
ALEXANDER COLLINS ◽  
CHRISTIAN FENSCH ◽  
HUGH LEATHER
Keyword(s):  
Execution Time ◽  
Human Expert ◽  
Programming Abstraction ◽  
Parallel Skeletons ◽  
Starting Point ◽  
Monte Carlo Search ◽  
Exploratory Data ◽  
Automatic Search ◽  
Two Parameters ◽  
The Cost

Parallel skeletons are a structured parallel programming abstraction that provide programmers with a predefined set of algorithmic templates that can be combined, nested and parameterized with sequential code to produce complex programs. The implementation of these skeletons is currently a manual process, requiring human expertise to choose suitable implementation parameters that provide good performance. This paper presents an empirical exploration of the optimization space of the FastFlow parallel skeleton framework. We performed this using a Monte Carlo search of a random subset of the space, for a representative set of platforms and programs. The results show that the space is program and platform dependent, non-linear, and that automatic search achieves a significant average speedup in program execution time of 1.6× over a human expert. An exploratory data analysis of the results shows a linear dependence between two of the parameters, and that another two parameters have little effect on performance. These properties are then used to reduce the size of the space by a factor of 6, reducing the cost of the search. This provides a starting point for automatically optimizing parallel skeleton programs without the need for human expertise, and with a large improvement in execution time compared to that achievable using human expert tuning.

scholarly journals Shape Preserving Interpolation UsingC2Rational Cubic Spline

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Samsul Ariffin Abdul Karim ◽  
Kong Voon Pang
Keyword(s):  
Spline Interpolation ◽  
Linear Equations ◽  
Sufficient Conditions ◽  
Cubic Spline ◽  
Shape Preserving ◽  
Cubic Spline Interpolation ◽  
Positive Data ◽  
Shape Preserving Interpolation ◽  
Systems Of Linear Equations ◽  
Two Parameters

This paper discusses the construction of newC2rational cubic spline interpolant with cubic numerator and quadratic denominator. The idea has been extended to shape preserving interpolation for positive data using the constructed rational cubic spline interpolation. The rational cubic spline has three parametersαi,βi, andγi. The sufficient conditions for the positivity are derived on one parameterγiwhile the other two parametersαiandβiare free parameters that can be used to change the final shape of the resulting interpolating curves. This will enable the user to produce many varieties of the positive interpolating curves. Cubic spline interpolation withC2continuity is not able to preserve the shape of the positive data. Notably our scheme is easy to use and does not require knots insertion andC2continuity can be achieved by solving tridiagonal systems of linear equations for the unknown first derivativesdi,i=1,…,n-1. Comparisons with existing schemes also have been done in detail. From all presented numerical results the newC2rational cubic spline gives very smooth interpolating curves compared to some established rational cubic schemes. An error analysis when the function to be interpolated isft∈C3t0,tnis also investigated in detail.

NONSMOOTH AND SMOOTH BIFURCATIONS IN A DISCONTINUOUS PIECEWISE MAP

2012 ◽  
Vol 22 (05) ◽  
pp. 1250112 ◽  
Author(s):  
ZHIYING QIN ◽  
YUEJING ZHAO ◽  
JICHEN YANG
Keyword(s):  
Fixed Point ◽  
Bifurcation Diagram ◽  
Bifurcation Point ◽  
Peculiar Feature ◽  
Parameter Plane ◽  
Flip Bifurcation ◽  
Border Collision Bifurcation ◽  
Bifurcation Structures ◽  
Piecewise Map ◽  
Two Parameter

In this paper, a piecewise map with singularity of the power (-1/2) is introduced. For this piecewise map, there is an infinite discontinuous gap on the origin. The conditions of nonsmooth border-collision bifurcation and smooth fold or flip bifurcation are analytically derived. For period-1 fixed point, two-parameter-plane can be divided into seven ranges according to different bifurcation structures. For period-n orbits, codimension-2 bifurcation point may lead to different period-increment sequence, and a peculiar feature is found that there are two different period-increment sequences in the same bifurcation diagram.

scholarly journals Architecture for Measuring Blade Tip Clearance and Time of Arrival with Multiple Sensors in Airplane Engines

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
José Miguel Gil-García ◽  
Joseba Zubia ◽  
Gerardo Aranguren
Keyword(s):  
Tip Clearance ◽  
Time Of Arrival ◽  
Multiple Sensors ◽  
Optic Sensor ◽  
Starting Point ◽  
Flexible Architecture ◽  
Blade Tip ◽  
Working Principle ◽  
Two Parameters ◽  
Blade Tip Clearance

The performance of airplane engines is influenced by the performance of their bladed disks. The loads those engines are under, both internal and external, are the origin of vibrations than can jeopardize their integrity. Traditionally, monitoring of those vibrations has been circumscribed to prototyping and quality tests of manufactured disks. However, the development of nonintrusive sensors and techniques to evaluate the vibration based on those sensors opens the monitoring of full engines, even onboard, to new possibilities. In order to assess the vibrations with these techniques, several sensors should be employed. The distance from the blade tip to the casing (tip clearance) and the time of arrival of a blade in front of the sensor are two parameters that are used as a starting point to characterize the vibrations. A flexible architecture to extract these parameters from the blades of a gas turbine has been developed. The generalization of this architecture is introduced which is able to deal with several sensors simultaneously. An implementation of this architecture has been carried out employing a trifurcated optic sensor, whose working principle is explained. A study of the resources required to implement this architecture on measurements of several optic sensors simultaneously and in parallel is presented. The architecture and measurement method have been validated using signals recorded during the test of the compressor stage with 146 blades on a turbine rig.

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