scholarly journals The Dissipative Properties Assessment of the Oscillatory System of a Serial Sample of the Coriolis Flowmeter

2020 ◽  
pp. 134-144
Author(s):  
V. A Romanov ◽  
P. A Taranenko
Keyword(s):  
Viscous Friction ◽  
Oscillatory System ◽  
Dissipated Energy ◽  
Dissipative Forces ◽  
Damped Oscillations ◽  
Fluid Flow Velocity ◽  
Coriolis Flowmeter ◽  
Coulomb Model ◽  
Processing Algorithms ◽  
Velocity Mode

The quantitative estimates of the flow rate (or density) of the flowing fluid obtained by the measurements using the industrial Coriolis flowmeters are made by using the laboratory experiments previously performed with the exemplary sensor. In this case we face two limitations, such as the unavailability of the facilities because of intense laboratory schedules and little time to upgrade the sensor oscillatory system. So we suggest using the virtual prototyping approaches as an alternative to the descriptive approaches. One of the fundamental problems of creating a virtual prototype of the Coriolis flowmeter is to separate the main parameter measured by the flowmeter (the phase shift) into the parts connected to the gyroscopic and dissipative forces. To solve this problem, we need to identify the dissipative forces model of the flowmeter oscillatory system. The article discusses the experimental results determining the dissipative properties of the mechanical oscillatory system of one of the commercially available Coriolis flowmeter samples. The algorithm identifying the model of the dissipative properties of the flowmeter oscillatory system is based on studying the nonlinearity degree of the envelope of the vibrogram of free damped oscillations. The experiments were carried out at the pouring stand of the Center for Experimental Mechanics of the South Ural State University, which allows controlling the speed and phase composition of the fluid flowing through the flowmeter. The article describes the processing algorithms for vibrograms of the damped oscillations, which make it possible to isolate the contribution into the dissipated energy from the dry (Coulomb model), the linear viscous (Rayleigh model) and quadratic viscous friction. The pronounced dependence of the vibrational system dissipation of the Coriolis flowmeter on the features of the fluid flow (velocity, mode: continuous, slug) was experimentally proven, the solutions of identifying the model of the dissipative forces are presented. The identification algorithm for the model of the dissipative properties of the flowmeter oscillatory system is based on studying the nonlinearity degree of the envelope of the vibrogram of the free damped oscillations. The use of the pouring stand made it possible to control the speed and phase composition of the fluid flowing through the flowmeter. The article describes the processing algorithms for the vibrograms of the damped oscillations by isolating the contribution into the dissipated energy from the dry (Coulomb model), linear viscous (Rayleigh model) and quadratic viscous friction. The pronounced dependence of the dissipation of the vibrational system of the Coriolis flowmeter on the features of the fluid flow (velocity, mode: continuous, slug) was experimentally proved, and the results of identifying the model of the dissipative forces are presented. The experiments included water acts as a fluid medium and air acts as a dispersed phase.

Ensemble Grey and Black-box Nonlinear System Identification of a Positioning System

2020 ◽  
Author(s):  
Walisson Chaves Ferreira Pinto ◽  
Helon Vicente Hultmann Ayala
Keyword(s):  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Viscous Friction ◽  
Black Box ◽  
Friction Model ◽  
Model Construction ◽  
Ensemble Model ◽  
Positioning System ◽  
Friction Models ◽  
Coulomb Model

In this work, grey and black-box approaches are used in order to model a electromechanical positioning system (EMPS). An ensemble model is then constructed by combining these two approaches, by using the predictions of both models in order to generate an improved estimated output. Four friction models, in their symmetric and asymmetric versions,namely (i) Coulomb model with finite slope at zero velocity and viscous friction, (ii) Coulomb model with viscous friction, (iii) Tustin friction model, (iv) Coulomb model with viscous friction and Stribeck effect were used to describe the dynamic behavior of the EMPS. The results have shown that the combination of grey and black-box models was able to perform better than the grey-box model and that the proposed friction models are also able to improve the relativeerror. This encourages further research on the application of the concept of ensemble model construction from machine learning to the nonlinear system identication context towards more accurate model construction.

scholarly journals STUDY POINTS OF REST HEREDITARITY DYNAMIC SYSTEMS VAN DER POL-DUFFING

2019 ◽  
pp. 71-77
Author(s):  
Е.Р. Новикова ◽  
Р.И. Паровик
Keyword(s):  
Limit Cycle ◽  
Dynamic Systems ◽  
Limit Cycles ◽  
Stable Limit Cycle ◽  
Viscous Friction ◽  
Oscillatory System ◽  
Stable Limit ◽  
Van Der Pol ◽  
Nonlinear Oscillatory System ◽  
Stable Limit Cycles

Using numerical modeling, oscillograms and phase trajectories were constructed to study the limit cycles of a van der Pol Duffing nonlinear oscillatory system with a power memory. The simulation results showed that in the absence of a power memory (α = 2, β = 1) or the classical van der Pol Duffing dynamical system, there is a single stable limit cycle, i.e. Lienar theorem holds. In the case of viscous friction (α = 2, 0 < β < 1), there is a family of stable limit cycles of various shapes. In other cases, the limit cycle is destroyed in two scenarios: a Hopf bifurcation (limit cycle-limit point) or (limit cycle-aperiodic process). Further continuation of the research may be related to the construction of the spectrum of Lyapunov maximal exponents in order to identify chaotic oscillatory regimes for the considered hereditary dynamic system (HDS). В работе с помощью численного моделирования построены осциллограммы и фазовые траектории с целью исследования предельных циклов нелинейной колебательной системы Ван-дер-Поля Дуффинга со степенной памятью. Результаты моделирования показали, что в случае отсутствия степенной памяти (α = 2, β = 1) или классической динамической системы Ван-дер-Поля Дуффинга, существует единственный устойчивый предельный цикл, т.е. выполняется теорема Льенара. В случае вязкого трения (α = 2, 0 < β < 1), существует семейство устойчивых предельных циклов различной формы. В остальных случаях происходит разрушение предельного цикла по двум сценариям: бифуркация Хопфа (предельный цикл-предельная точка) или (предельный циклапериодический процесс). Дальнейшее продолжение исследований может быть связано с построением спектра максимальных показателей Ляпунова с целью идентификации хаотических колебательных режимов для рассматриваемой эредитарной динамической системы (ЭДС).

scholarly journals Investigation of oscillatory displacement of the hydraulic presses moving parts during their braking in the upper initial position

2020 ◽  
Vol 99 (3) ◽  
pp. 66-74
Author(s):  
O. Korchak
Keyword(s):  
Mathematical Model ◽  
Numerical Analysis ◽  
Oscillatory System ◽  
Initial Position ◽  
Point Of View ◽  
Servo Drive ◽  
Inlet Valve ◽  
Starting Position ◽  
Damped Oscillations ◽  
The Mathematical Model

The investigations revealed that, despite the usage of individual servo drive of the inlet valve of return cylinders, ram overrun upwards after its being shut down which is accompanied by intensive oscillatory phenomena is inevitable. By analyzing the experimental diagrams it is stated that the existing mechanism of ram braking in upper starting position is unacceptable from the point of view of fast and non-impact process realization, as well as the accuracy of stoppage. The mathematical model of ram damped oscillations in the upper position after the inlet valve of return cylinders shut down, which takes into account the parameters of oscillatory system consisting of ram and fluid masses in power and return cylinders, is developed. A numerical analysis of the developed mathematical model established that when using counterbalance cylinders in press design, the period of oscillations increases with decreasing the amplitude. Besides, the complete damping of the oscillations occurs earlier than in the case of counterbalance cylinders absence.

Time Optimal Transfer Function of a Mechanism in the Presence of Dissipative Forces

2004 ◽  
Author(s):  
A. A. Goun ◽  
O. K. Sliva
Keyword(s):  
Dry Friction ◽  
Optimization Problems ◽  
Mechanical Energy ◽  
Operating Time ◽  
Variational Calculus ◽  
Viscous Friction ◽  
Optimal Position ◽  
Dissipative Forces ◽  
Time Optimal ◽  
Theoretical Mechanics

A variety of optimization problems in theoretical mechanics are related to the problem of finding the quickest operating mechanism among all possible mechanisms. Let us consider a mechanical system with one degree of freedom consisting of leading and lagging links with masses M1 and M2 respectively. Source of mechanical energy is attached to the leading link and its potential energy is known as a function of the position of the leading link. Positions of the leading - x and lagging links - y are related through the position function. Now the optimization problem can be formulated in the following way: find the position function such that the lagging link is transferred from initial to the final position in the shortest time. The analytic solution for this problem for the case when dissipative forces can be neglected was found using variational calculus method. In the case when dissipative forces can be described as viscous friction the problem can be solved using iterative methods. The differential equation that describes the stationary point of these iterations was obtained. The dependence of the optimal position function on the magnitude of friction is analyzed. In the case when dissipative forces are of the dry friction type the approach based on the variational calculus fails. We were able to find the optimal position function problem using Maximum Principle. New qualitative features of the solution arising due to dry friction are discussed. Approaches developed in this paper can be generalized for a variety of mechanisms where the operating time is critical.

Features of the system concepts of the dynamics of mechanical vibrational structures under asymmetric connections

2021 ◽  
pp. 4-16
Author(s):  
А. V. Eliseev ◽  
Keyword(s):  
Degrees Of Freedom ◽  
System Analysis ◽  
Viscous Friction ◽  
Oscillatory System ◽  
Gear Ratio ◽  
Topological Approach ◽  
Oscillatory Systems ◽  
Support Surfaces ◽  
Frequency Functions ◽  
Damping Functions

The paper is devoted to a new approach to the formation of the methodological basis of system analysis in application to problems of the dynamics of mechanical oscillatory systems taking into account the forces of viscous friction. A mechanical oscillatory system with two mass-inertia elements connected to the support surfaces and to each other by elastic-dissipative elements is considered. A method for estimating the free movements of a mechanical oscillatory system is developed based on the characteristics expressed in terms of the parameters of the lever connections between the partial blocks in the form of a gear ratio. Mathematical models are built on the basis of Lagrange formalism, algebraic methods, and the theory of functions of a complex variable. A matrix method is proposed for constructing frequency functions and damping functions for mechanical oscillatory systems with two degrees of freedom based on the ratio of the potential and kinetic energy of the system, taking into account the forces of viscous friction. For a mechanical system in which the connection of elements with a single reference surface is reset, a graphic analytic analysis of the extreme properties of the corresponding frequency functions and damping functions is performed. A topological approach is proposed.

Otoconia perfect/imperfect crystals

1994 ◽  
Vol 52 ◽  
pp. 42-43
Author(s):  
César D. Fermin ◽  
Dale Martin
Keyword(s):  
Image Processing ◽  
Room Temperature ◽  
Phosphotungstic Acid ◽  
Gallus Domesticus ◽  
Crystal Matrix ◽  
Organic Templates ◽  
Image Processing Algorithms ◽  
Processing Algorithms ◽  
Diffraction Patterns

Otoconia of higher vertebrates are interesting biological crystals that display the diffraction patterns of perfect crystals (e.g., calcite for birds and mammal) when intact, but fail to produce a regular crystallographic pattern when fixed. Image processing of the fixed crystal matrix, which resembles the organic templates of teeth and bone, failed to clarify a paradox of biomineralization described by Mann. Recently, we suggested that inner ear otoconia crystals contain growth plates that run in different directions, and that the arrangement of the plates may contribute to the turning angles seen at the hexagonal faces of the crystals.Using image processing algorithms described earlier, and Fourier Transform function (2FFT) of BioScan Optimas®, we evaluated the patterns in the packing of the otoconia fibrils of newly hatched chicks (Gallus domesticus) inner ears. Animals were fixed in situ by perfusion of 1% phosphotungstic acid (PTA) at room temperature through the left ventricle, after intraperitoneal Nembutal (35mg/Kg) deep anesthesia. Negatives were made with a Hitachi H-7100 TEM at 50K-400K magnifications. The negatives were then placed on a light box, where images were filtered and transferred to a 35 mm camera as described.

Analysis of field uniformity and quantitative evaluation of subsurface pitting corrosion in conductors via GPEC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 19-29
Author(s):  
Shuting Ren ◽  
Yong Li ◽  
Bei Yan ◽  
Jinhua Hu ◽  
Ilham Mukriz Zainal Abidin ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Eddy Current ◽  
Pitting Corrosion ◽  
Gradient Field ◽  
Uniform Field ◽  
Eddy Current Method ◽  
Optimal Position ◽  
Pulsed Eddy Current ◽  
Field Uniformity ◽  
Processing Algorithms

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.

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