scholarly journals Study of Dynamic Characteristics of Slow-Changing Process

2000 ◽  
Vol 7 (2) ◽  
pp. 113-117
Author(s):  
Yinong Li ◽  
Ling Zheng ◽  
Bangchun Wen
Keyword(s):  
Nonlinear System ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Asymptotic Method ◽  
Piecewise Linear ◽  
Linear Method ◽  
Vibration System ◽  
Intelligent Structures ◽  
Resonant Region ◽  
The Relationship

A vibration system with slow-changing parameters is a typical nonlinear system. Such systems often occur in the working and controlled process of some intelligent structures when vibration and deformation exist synchronously. In this paper, a system with slow-changing stiffness, damping and mass is analyzed in an intelligent structure. The relationship between the amplitude and the frequency of the system is studied, and its dynamic characteristic is also discussed. Finally, a piecewise linear method is developed on the basis of the asymptotic method. The simulation and the experiment show that a suitable slow-changing stiffness can restrain the amplitude of the system when the system passes through the resonant region.

A New Model for Simulating AC and Surge Properties of ZnO Varistors Based on Microstructural Characteristics

2008 ◽  
Vol 368-372 ◽  
pp. 510-513 ◽  
Author(s):  
Jun Hu ◽  
Jin Liang He ◽  
Feng Chao Luo
Keyword(s):  
Numerical Simulation ◽  
Grain Boundaries ◽  
Conduction Mechanism ◽  
Piecewise Linear ◽  
Linear Method ◽  
Microstructural Characteristics ◽  
Nonlinear Resistor ◽  
Resistor Networks ◽  
Zno Varistors ◽  
The Relationship

The numerical simulation is an effective method for researching the relationship between macroscopic properties of ZnO varistors and their microstructural characteristics. However, the computing efficiency is a big problem for further researches. In this paper, a quick piecewise linear method for solving the complicated nonlinear resistor networks of ZnO varistors is proposed, which can significantly improve the computing efficiency by a hundred times. The simulating models for the microstructural characteristics of ZnO varistors are improved based on actual conduction mechanism of grain boundaries. The simulations of more bulk characteristics of ZnO varistors become possible, such as alternating current (AC) and surge properties.

Dynamic Analysis of the Vibration System With Nonlinear Springs

2007 ◽  
Author(s):  
Guixi Li ◽  
Rujian Ma ◽  
Jungang Wang
Keyword(s):  
Numerical Simulation ◽  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Excitation Intensity ◽  
Vibration System ◽  
Analysis Method ◽  
Frequency Curve ◽  
Nonlinear Springs ◽  
The Relationship

The dynamic characteristics of vibration systems with nonlinear springs is analyzed in the paper. The relationship between spectra of response and excitation intensity is established by nonlinear analysis method under the assumption of the displacement response being a zero-mean Gaussian process, which is proved to be true by numerical simulation. The numerical computation is used to obtain the spectral densities of responses and, furthermore, to investigate the amplitude-frequency characteristics of the system. The results show that the peak of the amplitude-frequency curve goes higher with increase of the gap, yet lowers with the increase of natural frequency and drops significantly with the increase of damping ratio.

Influence of Suspension Mass Variation on Dynamic Characteristic of Magnetic Suspension System

2012 ◽  
Vol 150 ◽  
pp. 63-68 ◽  
Author(s):  
Xiao Guang Wang ◽  
Bin Mei ◽  
Feng Sha ◽  
Xin Zhou
Keyword(s):  
Nonlinear System ◽  
Dynamic Characteristic ◽  
Pid Control ◽  
Great Influence ◽  
Suspension System ◽  
Magnetic Suspension ◽  
Mass Variation ◽  
Magnetic Suspension System ◽  
The Relationship ◽  
Key Parameter

Magnetic suspension system is nonlinear and unstable essentially. It is according to the principle of nonlinear system having same topological structure near the operation point with the linear system that linear control arithmetic for a nonlinear system is adopted. The system is easy to lose stabilize and diverge when subjected to interference or system parameters variation. Suspension mass is a key parameter of a magnetic suspension system and suspension mass variation has great influence on the dynamic characteristic of a magnetic suspension system. The influence of suspension mass variation on the dynamic characteristic of a magnetic suspension system under the PID control condition is discussed. The relationship between dynamic characteristic and structure as well as control parameters of the magnetic suspension system is reached by means of experimental method.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

Association between Procalcitonin and Acute Kidney Injury in Patients with Bacterial Septic Shock

2021 ◽  
pp. 1-10
Author(s):  
Guang Fu ◽  
Hai-chao Zhan ◽  
Hao-li Li ◽  
Jun-fu Lu ◽  
Yan-hong Chen ◽  
...  
Keyword(s):  
Septic Shock ◽  
Acute Kidney Injury ◽  
Logistic Regression ◽  
Piecewise Linear ◽  
Kidney Injury ◽  
Multiple Logistic Regression ◽  
Primary Analysis ◽  
Female Patients ◽  
Potential Biomarker ◽  
The Relationship

Objective: The objective of this study was to assess the relationship between serum procalcitonin (PCT) and acute kidney injury (AKI) induced by bacterial septic shock. Methods: A retrospective study was designed which included patients who were admitted to the ICU from January 2015 to October 2018. Multiple logistic regression and receiver operating characteristic (ROC) as well as smooth curve fitting analysis were used to assess the relationship between the PCT level and AKI. Results: Of the 1,631 patients screened, 157 patients were included in the primary analysis in which 84 (53.5%) patients were with AKI. Multiple logistic regression results showed that PCT (odds ratio [OR] = 1.017, 95% confidence interval [CI] 1.009–1.025, p < 0.001) was associated with AKI induced by septic shock. The ROC analysis showed that the cutoff point for PCT to predict AKI development was 14 ng/mL, with a sensitivity of 63% and specificity 67%. Specifically, in multivariate piecewise linear regression, the occurrence of AKI decreased with the elevation of PCT when PCT was between 25 ng/mL and 120 ng/mL (OR 0.963, 95% CI 0.929–0.999; p = 0.042). The AKI increased with the elevation of PCT when PCT was either <25 ng/mL (OR 1.077, 95% CI 1.022–1.136; p = 0.006) or >120 ng/mL (OR 1.042, 95% CI 1.009–1.076; p = 0.013). Moreover, the PCT level was significantly higher in the AKI group only in female patients aged ≤75 years (p = 0.001). Conclusions: Our data revealed a nonlinear relationship between PCT and AKI in septic shock patients, and PCT could be used as a potential biomarker of AKI in female patients younger than 75 years with bacterial septic shock.

Experimental Research on Parameters Identification of Dynamic Characteristic for Parallel Machine Tool

2013 ◽  
Vol 300-301 ◽  
pp. 181-184
Author(s):  
Chun Xia Zhu ◽  
Zhi Wen Chen ◽  
Bo Liu ◽  
Jing Wang
Keyword(s):  
Optimal Design ◽  
Theoretical Analysis ◽  
Machine Tool ◽  
Dynamic Characteristic ◽  
Parallel Machine ◽  
Vibration System ◽  
Flexible Coupling ◽  
Vibration Model ◽  
Experiment Method ◽  
Parallel Machine Tool

The dynamic characteristics of parallel 3-TPT machine tool are researched by experiment in this paper. Firstly, modal analysis principle of machine tool was analyzed in theory, and the parameters of dynamic characteristic were identified by theoretical analysis. Then vibration model of parallel machine tool was built and formed vibration system of rigid and flexible coupling for analysis. Then, the modal experiment method and steps were introduced, and the experiment parameters also were identified according to the experiment results. The result dates are showed that the result dates are validated. So the experiment method is feasible by experimental verification, which provides reference for dynamic optimal design.

Analysis of the Dynamic Characteristics of the Firefly Algorithm

2020 ◽  
pp. 100-115
Author(s):  
Takuya Shindo
Keyword(s):  
Heuristic Algorithm ◽  
Dynamic Characteristics ◽  
Firefly Algorithm ◽  
Chaotic Behavior ◽  
Fundamental Principle ◽  
Deterministic System ◽  
Rigorous Analysis ◽  
The Individual ◽  
Searching Ability ◽  
The Relationship

The firefly algorithm is a meta-heuristic algorithm, the fundamental principle of which mimics the characteristics associated with the blinking of natural fireflies. This chapter presents a rigorous analysis of the dynamics of the firefly algorithm, which the authors performed by applying a deterministic system that removes the stochastic factors from the state update equation. Depending on its parameters, the individual deterministic firefly algorithm exhibits chaotic behavior. This prompted us to investigate the relationship between the behavior of the algorithm and its parameters as well as the extent to which the chaotic behavior influences the searching ability of the algorithm.

The Relationship between the Letters of Al-Iḫlāṣ (Q 112:1-4) and Their Iterations Using B-Spline Function

2019 ◽  
Vol 17 (1) ◽  
pp. 60-86
Author(s):  
Faoziya S.M. Musbah
Keyword(s):  
Spline Function ◽  
Piecewise Linear ◽  
Two Dimensional ◽  
B Spline ◽  
Holy Quran ◽  
Data Points ◽  
The Holy Quran ◽  
The Absolute ◽  
Unity Of God ◽  
The Relationship

Abstract Al-Iḫlāṣ is an important chapter within the Holy Quran (words of God) because it is a brief declaration of the absolute unity of God (Allah). This paper analyzes al-Iḫlāṣ mathematically in order to gain an understanding of the relationship between the letters of this chapter and their iterations. The analyzed two-dimensional data points (xi,yi) define a piecewise linear curve that is shaped like Allah’s name as it is written in Arabic. The B-spline function is used to analyze this data so as to obtain a second degree curve.

Simulation and Test Study on Dynamic Characteristic of Air Spring with Auxiliary Chamber

2013 ◽  
Vol 341-342 ◽  
pp. 391-394 ◽  
Author(s):  
Li Qing Sun ◽  
Zhong Xxing Li ◽  
Xu Feng Shen ◽  
Jia Yi Zhu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Excitation Frequency ◽  
Initial Pressure ◽  
Element Model ◽  
Air Spring ◽  
Chamber Volume ◽  
Lower Excitation

In order to improve dynamic characteristics of air spring with auxiliary chamber, finite element model of air spring R1A390-295 with auxiliary chamber connected with pipe is established,and through analysis to the dynamic characteristics of the model, influence discipline of sitffness characteristics to air spring with different pipe, different auxiliary chamber or different initial pressure are analysed under different excitation. The result show that:minor dynamic sitffness is obtained by using larger pipe or under lower excitation frequency,and as volume of auxiliary chamber increases, the spring dynamic sitffness will decrease accordingly and its amplitude tends to gentle,and influence for decreasing the spring dynamic sitffness is not obvious by continuing to increase the auxiliary chamber volume; the spring dynamic sitffness will increases as initial pressure increases. The validity of Finite element model is verified through dynamic characteristic test .

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