scholarly journals Moment Stability of the Critical Case of PWM Feedback Systems with Stochastic Perturbations

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Zhong Zhang ◽  
Lixia Ye
Keyword(s):  
Critical Case ◽  
Feedback System ◽  
Random Disturbance ◽  
Feedback Systems ◽  
Stochastic Perturbations ◽  
Pulse Width Modulated ◽  
Stability Bound ◽  
The Stability ◽  
The Moment ◽  
Moment Stability

This paper further studies the moment stability of pulse-width-modulated (PWM) feedback system which is subjected to multiplicative and additive random disturbance modeled by the derivative of Wiener process. Different from the existing investigation, we focus on its critical case. The linear plant considered herein is assumed to be critically stable; that is, the plant has one and only one pole at the origin, and the rest of the poles are left half of complex plane. We establish several globally asymptotically stability criteria for such PWM feedback systems and then propose an algorithm to calculate the stability bound effectively. Furthermore, we present two numerical examples to show the effectiveness of the theoretical results.

scholarly journals Stability Analysis of Pulse-Width-Modulated Feedback Systems with Time-Varying Delays

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Zhong Zhang ◽  
Huahui Han ◽  
Qiling Zhao ◽  
Lixia Ye
Keyword(s):  
Stability Analysis ◽  
Stability Problem ◽  
Pulse Width ◽  
Time Varying ◽  
Stability Criteria ◽  
Feedback Systems ◽  
Stochastic Perturbations ◽  
Pulse Width Modulated ◽  
The Stability ◽  
Moment Exponential Stability

The stability problem of pulse-width-modulated feedback systems with time-varying delays and stochastic perturbations is studied. With the help of an improved functional construction method, we establish a new Lyapunov-Krasovskii functional and derive several stability criteria aboutpth moment exponential stability.

ON THE WORKLOAD PROCESS IN A FLUID QUEUE WITH A RESPONSIVE BURSTY INPUT AND SELECTIVE DISCARDING

2003 ◽  
Vol 17 (4) ◽  
pp. 527-543
Author(s):  
Parijat Dube ◽  
Eitan Altman
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Feedback System ◽  
Moment Generating Function ◽  
General Distribution ◽  
Finite Buffer ◽  
Fluid Queue ◽  
The Stability ◽  
The Moment ◽  
Stationary Workload

We analyze a feedback system consisting of a finite buffer fluid queue and a responsive source. The source alternates between silence periods and active periods. At random epochs of times, the source becomes ready to send a burst of fluid. The length of the bursts (length of the active periods) are independent and identically distributed with some general distribution. The queue employs a threshold discarding policy in the sense that only those bursts at whose commencement epoch (the instant at which the source is ready to send) the workload (i.e., the amount of fluid in the buffer) is less than some preset threshold are accepted. If the burst is rejected then the source backs off from sending. We work within the framework of Poisson counter-driven stochastic differential equations and obtain the moment generating function and hence the probability density function of the stationary workload process. We then comment on the stability of this fluid queue. Our explicit characterizations will further provide useful insights and “engineering” guidelines for better network designing.

Optimal Model Reference Control Scheme Design for Nonlinear Strict-Feedback Systems

2020 ◽  
Vol 38 (9A) ◽  
pp. 1342-1351
Author(s):  
Musadaq A. Hadi ◽  
Hazem I. Ali
Keyword(s):  
Reference Model ◽  
Feedback System ◽  
Optimization Method ◽  
Feedback Systems ◽  
Model Reference ◽  
Scheme Design ◽  
Model Reference Control ◽  
Control Scheme ◽  
Lyapunov Stability Analysis ◽  
Strict Feedback

In this paper, a new design of the model reference control scheme is proposed in a class of nonlinear strict-feedback system. First, the system is analyzed using Lyapunov stability analysis. Next, a model reference is used to improve system performance. Then, the Integral Square Error (ISE) is considered as a cost function to drive the error between the reference model and the system to zero. After that, a powerful metaheuristic optimization method is used to optimize the parameters of the proposed controller. Finally, the results show that the proposed controller can effectively compensate for the strictly-feedback nonlinear system with more desirable performance.

scholarly journals Stability of Nonlinear Autonomous Quadratic Discrete Systems in the Critical Case

2010 ◽  
Vol 2010 ◽  
pp. 1-23 ◽  
Author(s):  
Josef Diblík ◽  
Denys Ya. Khusainov ◽  
Irina V. Grytsay ◽  
Zdenĕk Šmarda
Keyword(s):  
Lyapunov Functions ◽  
Critical Case ◽  
Autonomous Systems ◽  
Discrete Systems ◽  
Simple Eigenvalue ◽  
Discrete Equations ◽  
The Matrix ◽  
The Stability ◽  
Important Characterization

Many processes are mathematically simulated by systems of discrete equations with quadratic right-hand sides. Their stability is thought of as a very important characterization of the process. In this paper, the method of Lyapunov functions is used to derive classes of stable quadratic discrete autonomous systems in a critical case in the presence of a simple eigenvalueλ=1of the matrix of linear terms. In addition to the stability investigation, we also estimate stability domains.

Criteria for Recovery of Zero Initial Condition Responses of Unstable Plants Under Input Saturation

2000 ◽  
Author(s):  
Wei Wu ◽  
Suhada Jayasuriya
Keyword(s):  
Initial Conditions ◽  
Input Saturation ◽  
Input Sequence ◽  
Feedback System ◽  
Open Loop ◽  
Feedback Systems ◽  
Bounded Control ◽  
Analysis And Design ◽  
Study Results ◽  
Unstable Plant

Abstract In this paper, we consider the sufficient and/or necessary conditions under which responses of unstable plants with zero initial conditions would be bounded under step inputs. Several possible unstable pole patterns are examined, and corresponding criteria are derived. It is shown that an unstable plant can be stabilized to have bounded responses using an alternate step input sequence. Step inputs simulate the saturated inputs in a feedback system with bounded control, where the closed-loop stability of an unstable plant is really difficult to study. Results from this open-loop study may lend some insight into the analysis and design of such feedback systems under input saturation nonlinearities.

scholarly journals Surgery or general medicine: a study of the reasons underlying the choice of medical specialty

2004 ◽  
Vol 122 (3) ◽  
pp. 81-86 ◽  
Author(s):  
Patrícia Lacerda Bellodi
Keyword(s):  
Influencing Factor ◽  
Medical Knowledge ◽  
General Medicine ◽  
Medical Specialty ◽  
Educational Context ◽  
The Moment ◽  
Intellectual Activities ◽  
Brazilian Studies ◽  
Moment Stability ◽  
De Medicina

CONTEXT: The reality of medical services in Brazil points towards expansion and diversification of medical knowledge. However, there are few Brazilian studies on choosing a medical specialty. OBJECTIVE: To investigate and characterize the process of choosing the medical specialty among Brazilian resident doctors, with a comparison of the choice between general medicine and surgery. TYPE OF STUDY: Stratified survey. SETTING: Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HC-FMUSP). METHODS: A randomized sample of resident doctors in general medicine (30) and surgery (30) was interviewed. Data on sociodemographic characteristics and the moment, stability and reasons for the choice of specialty were obtained. RESULTS: The moment of choice between the two specialties differed. Surgeons (30%) choose the specialty earlier, while general doctors decided progressively, mainly during the internship (43%). Most residents in both fields (73% general medicine, 70% surgery) said they had considered another specialty before the current choice. The main reasons for general doctors' choice were contact with patients (50%), intellectual activities (30%) and knowledge of the field (27%). For surgeons the main reasons were practical intervention (43%), manual activities (43%) and the results obtained (40%). Personality was important in the choice for 20% of general doctors and for 27% of surgeons. DISCUSSION: The reasons found for the choice between general medicine and surgery were consistent with the literature. The concepts of wanting to be a general doctor or a surgeon are similar throughout the world. Personality characteristics were an important influencing factor for all residents, without statistical difference between the specialties, as was lifestyle. Remuneration did not appear as a determinant. CONCLUSION: The results from this group of Brazilian resident doctors corroborated data on choosing a medical specialty from other countries with different social and educational characteristics. This congruence indicates that the choice involves very similar desires and needs in different settings and has little dependence on the students' educational context.

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