System and method for determining stability of a neural system

Science.gov (United States)

Curtis, Steven A. (Inventor)

2011-01-01

Disclosed are methods, systems, and computer-readable media for determining stability of a neural system. The method includes tracking a function world line of an N element neural system within at least one behavioral space, determining whether the tracking function world line is approaching a psychological stability surface, and implementing a quantitative solution that corrects instability if the tracked function world line is approaching the psychological stability surface.

STABILITY OF LINEAR SYSTEMS WITH MARKOVIAN JUMPS

Directory of Open Access Journals (Sweden)

Jorge Enrique Mayta Guillermo

2016-12-01

Full Text Available In this work we will analyze the stability of linear systems governed by a Markov chain, this family is known in the specialized literature as linear systems with Markov jumps or by its acronyms in English MJLS as it is denoted in [1]. Linear systems governed by a Markov chain are dynamic systems with abrupt changes. We give some denitions of stability for the MJLS system, where these types of stability are equivalent as long as the state space of the Markov chain is nite. Finally we present a theorem that characterizes the stochastic stability by means of an equation of the Lyapunov type. The result is a generalization of a theorem in classical theory.

Long term stability of power systems

Energy Technology Data Exchange (ETDEWEB)

Kundur, P; Gao, B [Powertech Labs. Inc., Surrey, BC (Canada)

1994-12-31

Power system long term stability is still a developing subject. In this paper we provide our perspectives and experiences related to long term stability. The paper begins with the description of the nature of the long term stability problem, followed by the discussion of issues related to the modeling and solution techniques of tools for long term stability analysis. Cases studies are presented to illustrate the voltage stability aspect and plant dynamics aspect of long term stability. (author) 20 refs., 11 figs.

Fuzzy stability and synchronization of hyperchaos systems

International Nuclear Information System (INIS)

Wang Junwei; Xiong Xiaohua; Zhao Meichun; Zhang Yanbin

2008-01-01

This paper studies stability and synchronization of hyperchaos systems via a fuzzy-model-based control design methodology. First, we utilize a Takagi-Sugeno fuzzy model to represent a hyperchaos system. Second, we design fuzzy-model-based controllers for stability and synchronization of the system, based on so-called 'parallel distributed compensation (PDC)'. Third, we reduce a question of stabilizing and synchronizing hyperchaos systems to linear matrix inequalities (LMI) so that convex programming techniques can solve these LMIs efficiently. Finally, the generalized Lorenz hyperchaos system is employed to illustrate the effectiveness of our designing controller

Stability of digital feedback control systems

Directory of Open Access Journals (Sweden)

Larkin Eugene

2018-01-01

Lag time characteristics are used for investigation of stability of linear systems. Digital PID controller is divided onto linear part, which is realized with a soft and pure lag unit, which is realized with both hardware and software. With use notions amplitude and phase margins, condition for stability of system functioning are obtained. Theoretical results are confirm with computer experiment carried out on the third-order system.

Dynamic Stability Experiment of Maglev Systems,

Science.gov (United States)

1995-04-01

This report summarizes the research performed on maglev vehicle dynamic stability at Argonne National Laboratory during the past few years. It also... maglev system, it is important to consider this phenomenon in the development of all maglev systems. This report presents dynamic stability experiments...on maglev systems and compares their numerical simulation with predictions calculated by a nonlinear dynamic computer code. Instabilities of an

Finite-Time Stability and Stabilization of Nonlinear Quadratic Systems with Jumps

Directory of Open Access Journals (Sweden)

Minsong Zhang

2014-01-01

Full Text Available This paper investigates the problems of finite-time stability and finite-time stabilization for nonlinear quadratic systems with jumps. The jump time sequences here are assumed to satisfy some given constraints. Based on Lyapunov function and a particular presentation of the quadratic terms, sufficient conditions for finite-time stability and finite-time stabilization are developed to a set containing bilinear matrix inequalities (BLIMs and linear matrix inequalities (LMIs. Numerical examples are given to illustrate the effectiveness of the proposed methodology.

Evaluation and tuning of control algorithms for power system stabilizers; Evaluacion y sintonizacion de algoritmos de control para el estabilizador de sistemas de potencia

Energy Technology Data Exchange (ETDEWEB)

Ramirez Gonzalez, Miguel

1998-08-01

A procedure based on the phase compensation technique for tuning satisfactorily lead-lag power system stabilizers (PSS) is presented in this work. This procedure can be applied to standard models of PSS`s (with two phase compensation stages) where rotor speed deviation or an equivalent rotor speed signal is used as input. An analysis of several state of the art advanced control schemes is also presented, which are proposed for overcoming the limitations of conventional fixed parameters PSS`s. The advantages and drawbacks in designing certain types of PSS`s which are based on adaptive control, fuzzy logic and neural networks techniques are investigated. Based on this study, and taking into account the highly complex and non-linear nature of power systems, a fuzzy logic PSS is designed. In order to have good damping characteristics, speed deviation ({Delta}{omega}) of a machine and its acceleration ({Delta}{omega}) are chosen as the input signals to the fuzzy stabilizer of that particular machine. The performance of the lead-lag PSS and fuzzy stabilizer are validated through the simulation of two case studies: a single machine-infinite bus system, and a multimachine power system. All simulations were performed using a tool based on algorithms developed in MATLAB for the study of power system stability. [Espanol] Se presenta un procedimiento basado en la tecnica de compensacion de fase para ajustar en forma satisfactoria los parametros de los estabilizadores de sistemas de potencia (ESP) del tipo de adelanto-atraso. Este procedimiento es aplicable a modelos estandar de ESP`s (con dos redes de compensacion de fase) que utilizan como senal de entrada la velocidad del rotor del generador en cuestion, o una senal de velocidad equivalente. Por otra parte, se realiza un estudio de diversos esquemas de control avanzado del ESP que se proponen en la literatura actual para superar las limitantes de los estabilizadores convencionales. Basicamente, se analizan las ventajas y

Bank, Banking System, Macroprudential Supervision, Stability of Banking System

Directory of Open Access Journals (Sweden)

Tetiana Vasilyeva

2016-10-01

Full Text Available Intensification of financial development during last decade causes transformation of banking sector functioning. In particular, among the most significant changes over this period should be noted the next ones: convergence of financial market segments and appearance of cross-sector financial products, an increase of prevailing of financial sector in comparison with real economy and level of their interdependent, an intensification of crisis processes in financial and especially banking sector and a significant increase of the scale of the crisis consequences etc. thus, in such vulnerable conditions it is become very urgent to identify the relevant factors that can influence on the stability of banking sector, because its maintenance seems to be one of the most important preconditions of the stability of the national economy as a whole. Purpose of the article is to analyze key performance indicators of the Ukrainian banking system, clarify its main problems, identify relevant factors of the stability of the Ukrainian banking system and the character of their influence on the dependent variable. Realization of the mentioned above tasks was ensured by regression analysis (OLS regression. Analysis of key indicators that characterize current situation in the Ukrainian banking system found out the existence of numerous endogenous and exogenous problems, which, in turn, cause worsening most of analyzed indicators during 2013-2015. Unfavorable situation in Ukrainian banking system determined the necessity of identification of relevant factors of banking system stability to avoid transmission of financial shocks. According to the results of regression analysis on the stability of banking sector positively influence such factors as increase of interest margin to gross income ratio, reserves to assets ratio, number of branches, ratio of non-performing loans to total loans. Meanwhile, negative impact on stability of banking system has an increase of liquid

Stability analysis of fuzzy parametric uncertain systems.

Science.gov (United States)

Bhiwani, R J; Patre, B M

2011-10-01

In this paper, the determination of stability margin, gain and phase margin aspects of fuzzy parametric uncertain systems are dealt. The stability analysis of uncertain linear systems with coefficients described by fuzzy functions is studied. A complexity reduced technique for determining the stability margin for FPUS is proposed. The method suggested is dependent on the order of the characteristic polynomial. In order to find the stability margin of interval polynomials of order less than 5, it is not always necessary to determine and check all four Kharitonov's polynomials. It has been shown that, for determining stability margin of FPUS of order five, four, and three we require only 3, 2, and 1 Kharitonov's polynomials respectively. Only for sixth and higher order polynomials, a complete set of Kharitonov's polynomials are needed to determine the stability margin. Thus for lower order systems, the calculations are reduced to a large extent. This idea has been extended to determine the stability margin of fuzzy interval polynomials. It is also shown that the gain and phase margin of FPUS can be determined analytically without using graphical techniques. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Stability analysis of distributed order fractional chen system.

Science.gov (United States)

Aminikhah, H; Refahi Sheikhani, A; Rezazadeh, H

2013-01-01

We first investigate sufficient and necessary conditions of stability of nonlinear distributed order fractional system and then we generalize the integer-order Chen system into the distributed order fractional domain. Based on the asymptotic stability theory of nonlinear distributed order fractional systems, the stability of distributed order fractional Chen system is discussed. In addition, we have found that chaos exists in the double fractional order Chen system. Numerical solutions are used to verify the analytical results.

Stability Analysis of Distributed Order Fractional Chen System

Science.gov (United States)

Aminikhah, H.; Refahi Sheikhani, A.; Rezazadeh, H.

2013-01-01

We first investigate sufficient and necessary conditions of stability of nonlinear distributed order fractional system and then we generalize the integer-order Chen system into the distributed order fractional domain. Based on the asymptotic stability theory of nonlinear distributed order fractional systems, the stability of distributed order fractional Chen system is discussed. In addition, we have found that chaos exists in the double fractional order Chen system. Numerical solutions are used to verify the analytical results. PMID:24489508

Solar Dynamic Power System Stability Analysis and Control

Science.gov (United States)

Momoh, James A.; Wang, Yanchun

1996-01-01

The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

Stabilization of classic and quantum systems

International Nuclear Information System (INIS)

Buts, V.A.

2012-01-01

It is shown that the mechanism of quantum whirligig can be successfully used for stabilization of classical systems. In particular, the conditions for stabilization of charged particles and radiation fluxes in plasma are found.

Nonlinear physical systems spectral analysis, stability and bifurcations

CERN Document Server

Kirillov, Oleg N

2013-01-01

Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynam

Exponential Stability of Switched Positive Homogeneous Systems

Directory of Open Access Journals (Sweden)

Dadong Tian

2017-01-01

Full Text Available This paper studies the exponential stability of switched positive nonlinear systems defined by cooperative and homogeneous vector fields. In order to capture the decay rate of such systems, we first consider the subsystems. A sufficient condition for exponential stability of subsystems with time-varying delays is derived. In particular, for the corresponding delay-free systems, we prove that this sufficient condition is also necessary. Then, we present a sufficient condition of exponential stability under minimum dwell time switching for the switched positive nonlinear systems. Some results in the previous literature are extended. Finally, a numerical example is given to demonstrate the effectiveness of the obtained results.

System design description PFP thermal stabilization

International Nuclear Information System (INIS)

RISENMAY, H.R.

1998-01-01

The purpose of this document is to provide a system design description and design basis for the Plutonium Finishing P1ant (PFP) Thermal Stabilization project. The sources of material for this project are residues scraped from glovebox floors and materials already stored in vault storage that need further stabilizing to meet the 3013 storage requirements. Stabilizing this material will promote long term storage and reduced worker exposure. This document addresses: function design, equipment, and safety requirements for thermal stabilization of plutonium residues and oxides

Functional stability of cerebral circulatory system

Science.gov (United States)

Moskalenko, Y. Y.

1980-01-01

The functional stability of the cerebral circulation system seems to be based on the active mechanisms and on those stemming from specific of the biophysical structure of the system under study. This latter parameter has some relevant criteria for its quantitative estimation. The data obtained suggest that the essential part of the mechanism for active responses of cerebral vessels which maintains the functional stability of this portion of the vascular system, consists of a neurogenic component involving central nervous structures localized, for instance, in the medulla oblongata.

System evaluation of improved thermal stability jet fuels

Energy Technology Data Exchange (ETDEWEB)

Binns, K.E.; Dieterle, G.L.; Williams, T. [Univ. of Dayton Research Institute, OH (United States)

1995-05-01

A single-pass, single-tube heat exchanger device called the Phoenix rig and a single-pass, dual-heat exchanger system called the Extended Duration Thermal Stability Test system are specific devices/systems developed for evaluating jet fuel thermal stability. They have been used extensively in the evaluation of various jet fuels and thermal stability additives. The test results have indicated that additives can substantially improve the thermal stability of conventional jet fuels. Relationships of oxygen consumption, residence time, bulk, and wetted wall temperatures on coking deposits that form in the heated tubes have also been investigated.

Stability and response bounds of non-conservative linear systems

DEFF Research Database (Denmark)

Pommer, Christian

2003-01-01

For a linear system of second order differential equations the stability is studied by Lyapunov's direct method. The Lyapunov matrix equation is solved and a sufficient condition for stability is expressed by the system matrices. For a system which satisfies the condition for stability the Lyapunov...

On the stability of non-linear systems

International Nuclear Information System (INIS)

Guelman, M.

1968-09-01

A study is made of the absolute stability of nonlinear systems, using Liapounov's second method and taking into account the results obtained from V.M. Popov's work. The results already established are first presented, in particular concerning the frequency domain criterions for absolute stability of automatic control systems containing one single non linearity. The results have been extended to show the existence of a limiting parabola. New use is then made of the methods studied for deriving absolute stability criterions for a system containing a different type of non linearity. Finally, the results obtained are considered from the point of view of Aizerman's conjecture. (author) [fr

MHD stability analysis of helical system plasmas

International Nuclear Information System (INIS)

Nakamura, Yuji

2000-01-01

Several topics of the MHD stability studies in helical system plasmas are reviewed with respect to the linear and ideal modes mainly. Difference of the method of the MHD stability analysis in helical system plasmas from that in tokamak plasmas is emphasized. Lack of the cyclic (symmetric) coordinate makes an analysis more difficult. Recent topic about TAE modes in a helical system is also described briefly. (author)

On-line tuning of a fuzzy-logic power system stabilizer

International Nuclear Information System (INIS)

Hossein-Zadeh, N.; Kalam, A.

2002-01-01

A scheme for on-line tuning of a fuzzy-logic power system stabilizer is presented. firstly, a fuzzy-logic power system stabilizer is developed using speed deviation and accelerating power as the controller input variables. The inference mechanism of fuzzy-logic controller is represented by a decision table, constructed of linguistic IF-THEN rules. The Linguistic rules are available from experts and the design procedure is based on these rules. It assumed that an exact model of the plant is not available and it is difficult to extract the exact parameters of the power plant. Thus, the design procedure can not be based on an exact model. This is an advantage of fuzzy logic that makes the design of a controller possible without knowing the exact model of the plant. Secondly, two scaling parameters are introduced to tune the fuzzy-logic power system stabilizer. These scaling parameters are the outputs of another fuzzy-logic system, which gets the operating conditions of power system as inputs. These mechanism of tuning the fuzzy-logic power system stabilizer makes the fuzzy-logic power system stabilizer adaptive to changes in the operating conditions. Therefore, the degradation of the system response, under a wide range of operating conditions, is less compared to the system response with a fixed-parameter fuzzy-logic power system stabilizer and a conventional (linear) power system stabilizer. The tuned stabilizer has been tested by performing nonlinear simulations using a synchronous machine-infinite bus model. The responses are compared with a fixed parameters fuzzy-logic power system stabilizer and a conventional (linear) power system stabilizer. It is shown that the tuned fuzzy-logic power system stabilizer is superior to both of them

Dynamic postural stability in blind athletes using the biodex stability system.

Science.gov (United States)

Aydoğ, E; Aydoğ, S T; Cakci, A; Doral, M N

2006-05-01

Three systems affect the upright standing posture in humans - visual, vestibular, and somatosensory. It is well known that the visually impaired individuals have bad postural balance. On the other hand, it is a well documented fact that some sports can improve postural balance. Therefore, it is aimed in this study to evaluate the dynamic postural stability in goal-ball athletes. Twenty blind goal-ball players, 20 sighted and 20 sedentary blind controls were evaluated using the Biodex Stability System. Three adaptation trials and three test evaluations (a 20-second balance test at a platform stability of 8) were applied to the blind people, and to the sighted with eyes open and closed. Dynamic postural stability was measured on the basis of three indices: overall, anteroposterior, and mediolateral. Means of each test score were calculated. The tests results were compared for the blind athletes, sighted (with eyes open and closed) subjects, and sedentary blind people. There were significant differences between the results of the blind people and the sighted subjects with regards to all of the three indices. Although the stability of goal-ball players was better than sedentary blinds', only ML index values were statistically different (4.47 +/- 1.24 in the goal-ball players; 6.46 +/- 3.42 in the sedentary blind, p = 0.04). Dynamic postural stability was demonstrated to be affected by vision; and it was found that blind people playing goal-ball 1 - 2 days per week have higher ML stability than the sedentary sighted people.

On Stabilization of Nonautonomous Nonlinear Systems

International Nuclear Information System (INIS)

Bogdanov, A. Yu.

2008-01-01

The procedures to obtain the sufficient conditions of asymptotic stability for nonlinear nonstationary continuous-time systems are discussed. We consider different types of the following general controlled system: x = X(t,x,u) = F(t,x)+B(t,x)u, x(t 0 ) = x 0 . (*) The basis of investigation is limiting equations, limiting Lyapunov functions, etc. The improved concept of observability of the pair of functional matrices is presented. By these results the problem of synthesis of asymptotically stable control nonlinear nonautonomous systems (with linear parts) involving the quadratic time-dependent Lyapunov functions is solved as well as stabilizing a given unstable system with nonlinear control law.

Probabilistic assessment of power system transient stability incorporating SMES

Energy Technology Data Exchange (ETDEWEB)

Fang, Jiakun, E-mail: Jiakun.Fang@gmail.com [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Yao, Wei [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Wen, Jinyu, E-mail: jinyu.wen@hust.edu.cn [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Cheng, Shijie; Tang, Yuejin; Cheng, Zhuo [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)

2013-01-15

Highlights: ► Probabilistic study of power system with wind farm and SMES is proposed. ► Quantitative relationship between system stability and SMES capacity is given. ► System stability increases with the capacity of the SMES. ► System stability decreases with the penetration of wind power. ► Together with the cost function, the coil size is optimized. -- Abstract: This paper presents a stochastic-based approach to evaluate the probabilistic transient stability index of the power system incorporating the wind farm and the SMES. Uncertain factors include both sequence of disturbance in power grid and stochastic generation of the wind farm. The spectrums of disturbance in the grid as the fault type, the fault location, the fault clearing time and the automatic reclosing process with their probabilities of occurrence are used to calculate the probability indices, while the wind speed statistics and parameters of the wind generator are used in a Monte Carlo simulation to generate samples for the studies. With the proposed method, system stability is ”measured”. Quantitative relationship of penetration level, SMES coil size and system stability is established. Considering the stability versus coil size to be the production curve, together with the cost function, the coil size is optimized economically.

Probabilistic assessment of power system transient stability incorporating SMES

International Nuclear Information System (INIS)

Fang, Jiakun; Yao, Wei; Wen, Jinyu; Cheng, Shijie; Tang, Yuejin; Cheng, Zhuo

2013-01-01

Highlights: ► Probabilistic study of power system with wind farm and SMES is proposed. ► Quantitative relationship between system stability and SMES capacity is given. ► System stability increases with the capacity of the SMES. ► System stability decreases with the penetration of wind power. ► Together with the cost function, the coil size is optimized. -- Abstract: This paper presents a stochastic-based approach to evaluate the probabilistic transient stability index of the power system incorporating the wind farm and the SMES. Uncertain factors include both sequence of disturbance in power grid and stochastic generation of the wind farm. The spectrums of disturbance in the grid as the fault type, the fault location, the fault clearing time and the automatic reclosing process with their probabilities of occurrence are used to calculate the probability indices, while the wind speed statistics and parameters of the wind generator are used in a Monte Carlo simulation to generate samples for the studies. With the proposed method, system stability is ”measured”. Quantitative relationship of penetration level, SMES coil size and system stability is established. Considering the stability versus coil size to be the production curve, together with the cost function, the coil size is optimized economically

Some results on stability of difference systems

Directory of Open Access Journals (Sweden)

Xiao-Song Yang

2002-01-01

Full Text Available This paper presents some new results on existence and stability of equilibrium or periodic points for difference systems. First sufficient conditions of existence of asymptotically stable equilibrium point as well as the asymptotic stability of given equilibrium point are given for second order or delay difference systems. Then some similar results on existence of asymptotically stable periodic (equilibrium points to general difference systems are presented.

Stability Analysis for a Multi-Camera Photogrammetric System

Directory of Open Access Journals (Sweden)

Ayman Habib

2014-08-01

Full Text Available Consumer-grade digital cameras suffer from geometrical instability that may cause problems when used in photogrammetric applications. This paper provides a comprehensive review of this issue of interior orientation parameter variation over time, it explains the common ways used for coping with the issue, and describes the existing methods for performing stability analysis for a single camera. The paper then points out the lack of coverage of stability analysis for multi-camera systems, suggests a modification of the collinearity model to be used for the calibration of an entire photogrammetric system, and proposes three methods for system stability analysis. The proposed methods explore the impact of the changes in interior orientation and relative orientation/mounting parameters on the reconstruction process. Rather than relying on ground truth in real datasets to check the system calibration stability, the proposed methods are simulation-based. Experiment results are shown, where a multi-camera photogrammetric system was calibrated three times, and stability analysis was performed on the system calibration parameters from the three sessions. The proposed simulation-based methods provided results that were compatible with a real-data based approach for evaluating the impact of changes in the system calibration parameters on the three-dimensional reconstruction.

Stability improvement of induction generator-based wind turbine systems

DEFF Research Database (Denmark)

Chen, Zhe; Hu, Y.; Blaabjerg, Frede

2007-01-01

The stability improvement of induction-generator-based wind turbine systems under power system fault conditions has been studied. Two types of generators are considered, namely rotor short-circuited induction generators and dynamic slip-controlled wound rotor induction generators. The factors...... affecting the stability are analysed. The characteristics of the induction-generator-based wind turbines are described, and possible methods of improving stability of the wind generators are discussed. The system modelling is presented, and then the discussed methods of improving stability are investigated...

Power system stabilizers based on modern control techniques

Energy Technology Data Exchange (ETDEWEB)

Malik, O P; Chen, G P; Zhang, Y; El-Metwally, K [Calgary Univ., AB (Canada). Dept. of Electrical and Computer Engineering

1994-12-31

Developments in digital technology have made it feasible to develop and implement improved controllers based on sophisticated control techniques. Power system stabilizers based on adaptive control, fuzzy logic and artificial networks are being developed. Each of these control techniques possesses unique features and strengths. In this paper, the relative performance of power systems stabilizers based on adaptive control, fuzzy logic and neural network, both in simulation studies and real time tests on a physical model of a power system, is presented and compared to that of a fixed parameter conventional power system stabilizer. (author) 16 refs., 45 figs., 3 tabs.

Effects of SMES units on power system stability

International Nuclear Information System (INIS)

Byerly, R.T.; Juves, J.A.

1980-01-01

A mathematical model suitable for representing SMES units in power system stability studies has been developed and incorporated into an existing large-scale stability program. Demonstration studies have been performed which emphasize the use of SMES units to improve the damping of oscillations associated with synchronizing power flow among generators. The capability exists to conduct stability studies of large systems which include SMES units

Design of Simulation Product for Stability of Electric Power System Using Power System Stabilizer and Optimal Control

Science.gov (United States)

Junaidi, Agus; Hamid, K. Abdul

2018-03-01

This paper will discuss the use of optimal control and Power System Stabilizer (PSS) in improving the oscillation of electric power system. Oscillations in the electric power system can occur due to the sudden release of the load (Switcing-Off). The oscillation of an unstable system for a long time causes the equipment to work in an interruption. To overcome this problem, a control device is required that can work effectively in repairing the oscillation. The power system is modeled from the Single Machine Infinite Bus Model (SMIB). The state space equation is used to mathematically model SMIB. SMIB system which is a plant will be formed togetherness state variables (State-Space), using riccati equation then determined the optimal gain as controller plant. Plant is also controlled by Power Stabilizer System using phase compensation method. Using Matlab Software based simulation will be observed response of rotor speed change and rotor angle change for each of the two controlling methods. Simulation results using the Simulink-MATLAB 6.1 software will compare the analysis of the plant state in Open loop state and use the controller. The simulation response shows that the optimal control and PSS can improve the stability of the power system in terms of acceleration to achieve settling-time and Over Shoot improvement. From the results of both methods are able to improve system performance.

Stabilization at almost arbitrary points for chaotic systems

International Nuclear Information System (INIS)

Huang, C.-S.; Lian, K.-Y.; Su, C.-H.; Wu, J.-W.

2008-01-01

We consider how to design a feasible control input for chaotic systems via a suitable input channel to achieve the stabilization at arbitrary points. Regarding the nonlinear systems without naturally defined input vectors, we propose a local stabilization controller which works for almost arbitrary points. Subsequently, according to topologically transitive property for chaotic systems, the feedback control force is activated only when the trajectory passes through the neighboring region of the regulated point. Hence the global stabilization is achieved whereas the control effort of the hybrid controller is extremely low

Solving the stability-accuracy-diversity dilemma of recommender systems

Science.gov (United States)

Hou, Lei; Liu, Kecheng; Liu, Jianguo; Zhang, Runtong

2017-02-01

Recommender systems are of great significance in predicting the potential interesting items based on the target user's historical selections. However, the recommendation list for a specific user has been found changing vastly when the system changes, due to the unstable quantification of item similarities, which is defined as the recommendation stability problem. To improve the similarity stability and recommendation stability is crucial for the user experience enhancement and the better understanding of user interests. While the stability as well as accuracy of recommendation could be guaranteed by recommending only popular items, studies have been addressing the necessity of diversity which requires the system to recommend unpopular items. By ranking the similarities in terms of stability and considering only the most stable ones, we present a top- n-stability method based on the Heat Conduction algorithm (denoted as TNS-HC henceforth) for solving the stability-accuracy-diversity dilemma. Experiments on four benchmark data sets indicate that the TNS-HC algorithm could significantly improve the recommendation stability and accuracy simultaneously and still retain the high-diversity nature of the Heat Conduction algorithm. Furthermore, we compare the performance of the TNS-HC algorithm with a number of benchmark recommendation algorithms. The result suggests that the TNS-HC algorithm is more efficient in solving the stability-accuracy-diversity triple dilemma of recommender systems.

Stability of impulsive systems driven by renewal processes

NARCIS (Netherlands)

Guerreiro Tome Antunes, D.J.; Hespanha, J.P.; Silvestre, C.J.

2009-01-01

Necessary and sufficient conditions are provided for stochastic stability and mean exponential stability of impulsive systems with jumps triggered by a renewal process, that is, the intervals between jumps are independent and identically distributed. The conditions for stochastic stability can be

Robust stabilization of nonlinear systems: The LMI approach

Directory of Open Access Journals (Sweden)

Šiljak D. D.

2000-01-01

Full Text Available This paper presents a new approach to robust quadratic stabilization of nonlinear systems within the framework of Linear Matrix Inequalities (LMI. The systems are composed of a linear constant part perturbed by an additive nonlinearity which depends discontinuously on both time and state. The only information about the nonlinearity is that it satisfies a quadratic constraint. Our major objective is to show how linear constant feedback laws can be formulated to stabilize this type of systems and, at the same time, maximize the bounds on the nonlinearity which the system can tolerate without going unstable. We shall broaden the new setting to include design of decentralized control laws for robust stabilization of interconnected systems. Again, the LMI methods will be used to maximize the class of uncertain interconnections which leave the overall system connectively stable. It is useful to learn that the proposed LMI formulation “recognizes” the matching conditions by returning a feedback gain matrix for any prescribed bound on the interconnection terms. More importantly, the new formulation provides a suitable setting for robust stabilization of nonlinear systems where the nonlinear perturbations satisfy the generalized matching conditions.

Voltage stability analysis considering the load dynamic characteristics and the voltage control devices; Analisis de estabilidad de voltaje considerando las caracteristicas dinamicas de la carga y dispositivos de control de voltaje

Energy Technology Data Exchange (ETDEWEB)

Hernandez Alvarez, Enrique

2001-09-15

improvement of the voltage stability. Finally, the application of the proposed methods of study to the analysis of voltage stability in an electrical network derived from the Mexican Peninsular system is presented. The influence of voltage control devices in the stability phenomenon is discussed and a comparison with the results obtained by means of other analysis techniques are presented, specifically, the study of the Q-V curves and the modal analysis of the power flow equations. [Spanish] El trabajo de investigacion que se presenta en esta tesis se centra en el analisis de la estabilidad de voltaje de mediano plazo considerando el efecto de las caracteristicas de la carga y su interaccion con los modelos de dispositivos de control de voltaje en la red de transmision. Mas concretamente, se define y estudia un tipo de modelo de carga con caracteristicas deseables para el estudio de la estabilidad de voltaje; los modelos genericos de carga derivados de pruebas de campo o de la aplicacion de tecnicas de identificacion y se analiza la influencia de la aplicacion de dispositivos de control para mejorar los margenes de estabilidad del sistema. Se estudian, asimismo, alternativas al modelado de sistemas de potencia para el estudio de la estabilidad de voltaje en sistemas complejos. Se presenta, en primer lugar, un analisis fundamental de las caracteristicas de estabilidad de voltaje en un sistema simplificado de potencia y se introduce el metodo de analisis adoptado. Se muestra que el fenomeno de inestabilidad se manifiesta como una bifurcacion tipo singular inducida del modo critico de voltaje cuando se opera el sistema bajo condiciones de estres. A continuacion, se analiza la contribucion de la accion de dispositivos de control al margen de estabilidad y se deducen criterios de analisis de estabilidad basados en el estudio de dicho modo. Se propone, a continuacion, un modelo lineal del sistema de potencia con caracteristicas deseables para el estudio de la estabilidad de voltaje

The Nature of Stability in Replicating Systems

Directory of Open Access Journals (Sweden)

Addy Pross

2011-02-01

Full Text Available We review the concept of dynamic kinetic stability, a type of stability associated specifically with replicating entities, and show how it differs from the well-known and established (static kinetic and thermodynamic stabilities associated with regular chemical systems. In the process we demonstrate how the concept can help bridge the conceptual chasm that continues to separate the physical and biological sciences by relating the nature of stability in the animate and inanimate worlds, and by providing additional insights into the physicochemical nature of abiogenesis.

Stabilization of model-based networked control systems

Energy Technology Data Exchange (ETDEWEB)

Miranda, Francisco [CIDMA, Universidade de Aveiro, Aveiro (Portugal); Instituto Politécnico de Viana do Castelo, Viana do Castelo (Portugal); Abreu, Carlos [Instituto Politécnico de Viana do Castelo, Viana do Castelo (Portugal); CMEMS-UMINHO, Universidade do Minho, Braga (Portugal); Mendes, Paulo M. [CMEMS-UMINHO, Universidade do Minho, Braga (Portugal)

2016-06-08

A class of networked control systems called Model-Based Networked Control Systems (MB-NCSs) is considered. Stabilization of MB-NCSs is studied using feedback controls and simulation of stabilization for different feedbacks is made with the purpose to reduce the network trafic. The feedback control input is applied in a compensated model of the plant that approximates the plant dynamics and stabilizes the plant even under slow network conditions. Conditions for global exponential stabilizability and for the choosing of a feedback control input for a given constant time between the information moments of the network are derived. An optimal control problem to obtain an optimal feedback control is also presented.

Stability of molecular dynamics simulations of classical systems

DEFF Research Database (Denmark)

Toxværd, Søren

2012-01-01

The existence of a shadow Hamiltonian for discrete classical dynamics, obtained by an asymptotic expansion for a discrete symplectic algorithm, is employed to determine the limit of stability for molecular dynamics (MD) simulations with respect to the time-increment h of the discrete dynamics....... The investigation is based on the stability of the shadow energy, obtained by including the first term in the asymptotic expansion, and on the exact solution of discrete dynamics for a single harmonic mode. The exact solution of discrete dynamics for a harmonic potential with frequency ω gives a criterion...... for the limit of stability h ⩽ 2/ω. Simulations of the Lennard-Jones system and the viscous Kob-Andersen system show that one can use the limit of stability of the shadow energy or the stability criterion for a harmonic mode on the spectrum of instantaneous frequencies to determine the limit of stability of MD...

Boundary feedback stabilization of distributed parameter systems

DEFF Research Database (Denmark)

Pedersen, Michael

1988-01-01

The author introduces the method of pseudo-differential stabilization. He notes that the theory of pseudo-differential boundary operators is a fruitful approach to problems arising in control and stabilization theory of distributed-parameter systems. The basic pseudo-differential calculus can...

Frequency scanning-based stability analysis method for grid-connected inverter system

DEFF Research Database (Denmark)

Wang, Yanbo; Wang, Xiongfei; Blaabjerg, Frede

2017-01-01

This paper proposes a frequency scanning-based impedance analysis for stability assessment of grid-connected inverter system, which is able to perform stability assessment without using system mathematical models and inherit the superior feature of impedance-based stability criterion with conside......This paper proposes a frequency scanning-based impedance analysis for stability assessment of grid-connected inverter system, which is able to perform stability assessment without using system mathematical models and inherit the superior feature of impedance-based stability criterion...... with consideration of the inverter nonlinearities. Small current disturbance is injected into grid-connected inverter system in a particular frequency range, and the impedance is computed according to the harmonic-frequency response using Fourier analysis, and then the stability is predicted on the basis...... of the impedance stability criterion. The stability issues of grid-connected inverters with grid-current feedback and the converter-current feedback are addressed using the proposed method. The results obtained from simulation and experiments validate the effectiveness of the method. The frequency scanning...

Stability Analysis of Fractional-Order Nonlinear Systems with Delay

Directory of Open Access Journals (Sweden)

Yu Wang

2014-01-01

Full Text Available Stability analysis of fractional-order nonlinear systems with delay is studied. We propose the definition of Mittag-Leffler stability of time-delay system and introduce the fractional Lyapunov direct method by using properties of Mittag-Leffler function and Laplace transform. Then some new sufficient conditions ensuring asymptotical stability of fractional-order nonlinear system with delay are proposed firstly. And the application of Riemann-Liouville fractional-order systems is extended by the fractional comparison principle and the Caputo fractional-order systems. Numerical simulations of an example demonstrate the universality and the effectiveness of the proposed method.

Model predictive control of hybrid systems : stability and robustness

NARCIS (Netherlands)

Lazar, M.

2006-01-01

This thesis considers the stabilization and the robust stabilization of certain classes of hybrid systems using model predictive control. Hybrid systems represent a broad class of dynamical systems in which discrete behavior (usually described by a finite state machine) and continuous behavior

Stability of magnetic tip/superconductor levitation systems

International Nuclear Information System (INIS)

Alqadi, M. K.

2015-01-01

The vertical stability of a magnetic tip over a superconducting material is investigated by using the critical state and the frozen image models. The analytical expressions of the stiffness and the vibration frequency about the equilibrium position are derived in term of the geometrical parameters of the magnet/superconductor system. It is found that the stability of the system depends on the shape of the superconductor as well as its thickness. (paper)

An equivalent condition for stability properties of Lotka-Volterra systems

International Nuclear Information System (INIS)

Chu Tianguang

2007-01-01

We give a solvable Lie algebraic condition for the equivalence of four typical stability notions (asymptotic stability, D-stability, total stability, and Volterra-Lyapunov stability) concerning Lotka-Volterra systems. Our approach makes use of the decomposition of the interaction matrix into symmetric and skew-symmetric parts, which may be related to the cooperative and competitive interaction pattern of a Lotka-Volterra system. The present result covers a known condition and can yield a larger set of interaction matrices for equivalence of the stability properties

Robust design of decentralized power system stabilizers using meta-heuristic optimization techniques for multimachine systems

Directory of Open Access Journals (Sweden)

Jeevanandham Arumugam

2009-01-01

Full Text Available In this paper a classical lead-lag power system stabilizer is used for demonstration. The stabilizer parameters are selected in such a manner to damp the rotor oscillations. The problem of selecting the stabilizer parameters is converted to a simple optimization problem with an eigen value based objective function and it is proposed to employ simulated annealing and particle swarm optimization for solving the optimization problem. The objective function allows the selection of the stabilizer parameters to optimally place the closed-loop eigen values in the left hand side of the complex s-plane. The single machine connected to infinite bus system and 10-machine 39-bus system are considered for this study. The effectiveness of the stabilizer tuned using the best technique, in enhancing the stability of power system. Stability is confirmed through eigen value analysis and simulation results and suitable heuristic technique will be selected for the best performance of the system.

Power system small signal stability analysis and control

CERN Document Server

Mondal, Debasish; Sengupta, Aparajita

2014-01-01

Power System Small Signal Stability Analysis and Control presents a detailed analysis of the problem of severe outages due to the sustained growth of small signal oscillations in modern interconnected power systems. The ever-expanding nature of power systems and the rapid upgrade to smart grid technologies call for the implementation of robust and optimal controls. Power systems that are forced to operate close to their stability limit have resulted in the use of control devices by utility companies to improve the performance of the transmission system against commonly occurring power system

Stabilization of switched nonlinear systems with unstable modes

CERN Document Server

Yang, Hao; Cocquempot, Vincent

2014-01-01

This book provides its reader with a good understanding of the stabilization of switched nonlinear systems (SNS), systems that are of practical use in diverse situations: design of fault-tolerant systems in space- and aircraft; traffic control; and heat propagation control of semiconductor power chips. The practical background is emphasized throughout the book; interesting practical examples frequently illustrate the theoretical results with aircraft and spacecraft given particular prominence. Stabilization of Switched Nonlinear Systems with Unstable Modes treats several different subclasses of SNS according to the characteristics of the individual system (time-varying and distributed parameters, for example), the state composition of individual modes and the degree and distribution of instability in its various modes. Achievement and maintenance of stability across the system as a whole is bolstered by trading off between individual modes which may be either stable or unstable, or by exploiting areas of part...

On a program manifold's stability of one contour automatic control systems

Science.gov (United States)

Zumatov, S. S.

2017-12-01

Methodology of analysis of stability is expounded to the one contour systems automatic control feedback in the presence of non-linearities. The methodology is based on the use of the simplest mathematical models of the nonlinear controllable systems. Stability of program manifolds of one contour automatic control systems is investigated. The sufficient conditions of program manifold's absolute stability of one contour automatic control systems are obtained. The Hurwitz's angle of absolute stability was determined. The sufficient conditions of program manifold's absolute stability of control systems by the course of plane in the mode of autopilot are obtained by means Lyapunov's second method.

Wind energy systems solutions for power quality and stabilization

CERN Document Server

Ali, Mohd Hasan

2012-01-01

Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases--and wind energy is a free, renewable resource. However, the induction machines commonly used as wind generators have stability problems similar to the transient stability of synchronous machines. To minimize power, frequency, and voltage fluctuations caused by network faults or random wind speed variations, control mechanisms are necessary. Wind Energy Systems: Solutions for Power Quality and Stabilization clearly explains how to solve stability and power quality issues of wind generator systems. Covering

Power stability methods for parallel systems

International Nuclear Information System (INIS)

Wallach, Y.

1988-01-01

Parallel-Processing Systems are already commercially available. This paper shows that if one of them - the Alternating Sequential Parallel, or ASP system - is applied to network stability calculations it will lead to a higher speed of solution. The ASP system is first described and is then shown to be cheaper, more reliable and available than other parallel systems. Also, no deadlock need be feared and the speedup is normally very high. A number of ASP systems were already assembled (the SMS systems, Topps, DIRMU etc.). At present, an IBM Local Area Network is being modified so that it too can work in the ASP mode. Existing ASP systems were programmed in Fortran or assembly language. Since newer systems (e.g. DIRMU) are programmed in Modula-2, this language can be used. Stability analysis is based on solving nonlinear differential and algebraic equations. The algorithm for solving the nonlinear differential equations on ASP, is described and programmed in Modula-2. The speedup is computed and is shown to be almost optimal

Stability and delay sensitivity of neutral fractional-delay systems.

Science.gov (United States)

Xu, Qi; Shi, Min; Wang, Zaihua

2016-08-01

This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

Stability Tests of Positive Fractional Continuous-time Linear Systems with Delays

Directory of Open Access Journals (Sweden)

Tadeusz Kaczorek

2013-06-01

Full Text Available Necessary and sufficient conditions for the asymptotic stability of positive fractional continuous-time linear systems with many delays are established. It is shown that: 1 the asymptotic stability of the positive fractional system is independent of their delays, 2 the checking of the asymptotic stability of the positive fractional systems with delays can be reduced to checking of the asymptotic stability of positive standard linear systems without delays.

Estudios Experimentales 2 Parte: Estudios Cuasi-Experimentales

OpenAIRE

Manterola, Carlos; Otzen, Tamara

2015-01-01

Los estudios experimentales, se caracterizan por la valoración del efecto de una o más intervenciones, habitualmente de forma comparativa con otra intervención, o un placebo; y el carácter prospectivo, de la recolección de datos y seguimiento. Agrupados bajo esta denominación, existe una diversidad de diseños, entre los que se encuentran los estudios cuasi-experimentales (ECE), que se caracterizan especialmente por la ausencia de asignación aleatoria. El objetivo de este manuscrito, es report...

Morocco; Financial System Stability Assessment

OpenAIRE

International Monetary Fund

2003-01-01

The Financial System Stability Assessment of Morocco reviews the reform program that is aimed at establishing a modern, market-oriented financial system that optimizes the mobilization of savings and the allocation of financial resources. It reviews the modernization of the banking sector and the development of competition within the sector, development of financial markets, and removal of constraints on financial system activity. It also provides reports on the Observance of Standards and Co...

Review of Power System Stability with High Wind Power Penetration

DEFF Research Database (Denmark)

Hu, Rui; Hu, Weihao; Chen, Zhe

2015-01-01

analyzing methods and stability improvement approaches. With increasing wind power penetration, system balancing and the reduced inertia may cause a big threaten for stable operation of power systems. To mitigate or eliminate the wind impacts for high wind penetration systems, although the practical......This paper presents an overview of researches on power system stability with high wind power penetration including analyzing methods and improvement approaches. Power system stability issues can be classified diversely according to different considerations. Each classified issue has special...... and reliable choices currently are the strong outside connections or sufficient reserve capacity constructions, many novel theories and approaches are invented to investigate the stability issues, looking forward to an extra-high penetration or totally renewable resource based power systems. These analyzing...

Preparation of Astaxanthin Nanodispersions Using Gelatin-Based Stabilizer Systems

Directory of Open Access Journals (Sweden)

Navideh Anarjan

2014-09-01

Full Text Available The incorporation of lipophilic nutrients, such as astaxanthin (a fat soluble carotenoid in nanodispersion systems can either increase the water solubility, stability and bioavailability or widen their applications in aqueous food and pharmaceutical formulations. In this research, gelatin and its combinations with sucrose oleate as a small molecular emulsifier, sodium caseinate (SC as a protein and gum Arabic as a polysaccharide were used as stabilizer systems in the formation of astaxanthin nanodispersions via an emulsification-evaporation process. The results indicated that the addition of SC to gelatin in the stabilizer system could increase the chemical stability of astaxanthin nanodispersions significantly, while using a mixture of gelatin and sucrose oleate as a stabilizer led to production of nanodispersions with the smallest particle size (121.4 ± 8.6 nm. It was also shown that a combination of gelatin and gum Arabic could produce optimal astaxanthin nanodispersions in terms of physical stability (minimum polydispersity index (PDI and maximum zeta-potential. This study demonstrated that the mixture of surface active compounds showed higher emulsifying and stabilizing functionality compared to using them individually in the preparation of astaxanthin nanodispersions.

Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

Directory of Open Access Journals (Sweden)

Yuling Li

2018-01-01

Full Text Available The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

Asymptotic stabilization of nonlinear systems using state feedback

International Nuclear Information System (INIS)

D'Attellis, Carlos

1990-01-01

This paper studies the design of state-feedback controllers for the stabilization of single-input single-output nonlinear systems x = f(x) + g(x)u, y = h(x). Two approaches for the stabilization problem are given; the asymptotic stability is achieved by means of: a) nonlinear state feedback: two nonlinear feedbacks are used; the first separates the system in a controllable linear part and in the zeros-dynamic part. The second feedback generates an asymptotically stable equilibrium on the manifold where this dynamics evolves; b) nonlinear dynamic feedback: conditions are established under which the system can follow the output of a completely controllable bilinear system which uses bounded controls. This fact enables the system to reach, using bounded controls too, a desired output value in finite time. As this value corresponds to a state that lays in the attraction basin of a stable equilibrium with the same output, the system evolves to that point. The two methods are illustrated by examples. (Author) [es

A study of offshore wind HVDC system stability and control

Energy Technology Data Exchange (ETDEWEB)

Liu, Hanchao; Sun, Jian [Rensselaer Polytechnic Institute, Troy, NY (United States). Dept. of Electrical, Computer and Systems Engineering

2011-07-01

This work is concerned with the stability and control of ac power collection buses in offshore wind farms with high-voltage dc (HVDC) transmission connection to onshore power grid. The focus of the work is high-frequency interactions among the wind turbines, the ac collection bus and the filters, as well as the HVDC rectifier. Both voltage-source converter and line-commutated converter based HVDC systems are considered. To study high-frequency stability, particularly harmonic resonance in the ac bus, small-signal impedance models are developed for the wind inverters and the HVDC rectifier by using harmonic linearization techniques. An impedance-based stability criterion is applied to assess system stability in both positive- and negative-sequence domain. Small-signal stability conditions and requirements are developed from analytical impedance models. Detailed system-level simulation is used to validated the small-signal analysis. The goal of the study is to develop system design and control techniques that minimize the cost of the offshore infrastructure while guaranteeing system stability and power quality. (orig.)

Congestion management enhancing transient stability of power systems

International Nuclear Information System (INIS)

Esmaili, Masoud; Shayanfar, Heidar Ali; Amjady, Nima

2010-01-01

In a competitive electricity market, where market parties try to maximize their profits, it is necessary to keep an acceptable level of power system security to retain the continuity of electricity services to customers at a reasonable cost. Congestion in a power system is turned up due to network limits. After relieving congestion, the network may be operated with a reduced transient stability margin because of increasing the contribution of risky participants. In this paper, a novel congestion management method based on a new transient stability criterion is introduced. Using the sensitivity of corrected transient stability margin with respect to generations and demands, the proposed method so alleviates the congestion that the network can more retain its transient security compared with earlier methods. The proposed transient stability index is constructed considering the likelihood of credible faults. Indeed, market parties participate by their security-effective bids rather than raw bids. Results of testing the proposed method along with the earlier ones on the New-England test system elaborate the efficiency of the proposed method from the viewpoint of providing a better transient stability margin with a lower security cost. (author)

The algebraic criteria for the stability of control systems

Science.gov (United States)

Cremer, H.; Effertz, F. H.

1986-01-01

This paper critically examines the standard algebraic criteria for the stability of linear control systems and their proofs, reveals important previously unnoticed connections, and presents new representations. Algebraic stability criteria have also acquired significance for stability studies of non-linear differential equation systems by the Krylov-Bogoljubov-Magnus Method, and allow realization conditions to be determined for classes of broken rational functions as frequency characteristics of electrical network.

Wavelength stabilized multi-kW diode laser systems

Science.gov (United States)

Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

2015-03-01

We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

Preservation of stability and synchronization in nonlinear systems

International Nuclear Information System (INIS)

Fernandez-Anaya, G.; Flores-Godoy, J.J.; Femat, R.; Alvarez-Ramirez, J.J.

2007-01-01

Preservation of stability in the presence of structural and/or parametric changes is an important issue in the study of dynamical systems. A specific case is the synchronization of chaos in complex networks where synchronization should be preserved in spite of changes in the network parameters and connectivity. In this work, a methodology to establish conditions for preservation of stability in a class of dynamical system is given in terms of Lyapunov methods. The idea is to construct a group of dynamical transformations under which stability is retained along certain manifolds. Some synchronization examples illustrate the results

Preservation of stability and synchronization in nonlinear systems

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Anaya, G. [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prol. Paseo de la Reforma 880, Lomas de Santa Fe, Mexico, D.F. 01210 (Mexico)], E-mail: guillermo.fernandez@uia.mx; Flores-Godoy, J.J. [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prol. Paseo de la Reforma 880, Lomas de Santa Fe, Mexico, D.F. 01210 (Mexico)], E-mail: job.flores@uia.mx; Femat, R. [Division de Matematicas Aplicadas y Sistemas Computacionales, IPICyT, Camino a la Presa San Jose 2055, Col. Lomas 4a. seccion, San Luis Potosi, San Luis Potosi 78216 (Mexico)], E-mail: rfemat@ipicyt.edu.mx; Alvarez-Ramirez, J.J. [Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico, D.F. 09340 (Mexico)], E-mail: jjar@xanum.uam.mx

2007-11-12

Preservation of stability in the presence of structural and/or parametric changes is an important issue in the study of dynamical systems. A specific case is the synchronization of chaos in complex networks where synchronization should be preserved in spite of changes in the network parameters and connectivity. In this work, a methodology to establish conditions for preservation of stability in a class of dynamical system is given in terms of Lyapunov methods. The idea is to construct a group of dynamical transformations under which stability is retained along certain manifolds. Some synchronization examples illustrate the results.

Harmonics and voltage stability analysis in power systems including ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

two parameters affecting power quality – harmonics and voltage stability. ... is necessary to pay attention to energy system stability in the planning, management, and ... where k ∈ {m, m + 1,... ,n} and n is total number of the buses in the system.

Stability Analysis of Neural Networks-Based System Identification

Directory of Open Access Journals (Sweden)

Talel Korkobi

2008-01-01

Full Text Available This paper treats some problems related to nonlinear systems identification. A stability analysis neural network model for identifying nonlinear dynamic systems is presented. A constrained adaptive stable backpropagation updating law is presented and used in the proposed identification approach. The proposed backpropagation training algorithm is modified to obtain an adaptive learning rate guarantying convergence stability. The proposed learning rule is the backpropagation algorithm under the condition that the learning rate belongs to a specified range defining the stability domain. Satisfying such condition, unstable phenomena during the learning process are avoided. A Lyapunov analysis leads to the computation of the expression of a convenient adaptive learning rate verifying the convergence stability criteria. Finally, the elaborated training algorithm is applied in several simulations. The results confirm the effectiveness of the CSBP algorithm.

Performance of the PBX-M passive plate stabilization system

International Nuclear Information System (INIS)

Kugel, H.W.; Bell, R.; Bernabei, S.

1994-02-01

The PBX-M passive plate stabilization system provides significant stabilization of long-wavelength external kink modes, the slowing of vertical instability growth rates, and the amelioration of disruption characteristics. The passive plate stabilization system has allowed the use of LHCD and IBW to induce current density and pressure profile modifications, and m = 1 divertor biasing for modifying edge plasma transport. Improvements in the passive plate system insulators and support structures have provided reliable operation. Impurity influxes with the close-fitting passive plates are low. Solid target boronization is applied routinely to reduce conditioning time and maintain clean conditions

Stability and stabilization of linear systems with saturating actuators

CERN Document Server

Tarbouriech, Sophie; Gomes da Silva Jr, João Manoel; Queinnec, Isabelle

2011-01-01

Gives the reader an in-depth understanding of the phenomena caused by the more-or-less ubiquitous problem of actuator saturation. Proposes methods and algorithms designed to avoid, manage or overcome the effects of actuator saturation. Uses a state-space approach to ensure local and global stability of the systems considered. Compilation of fifteen years' worth of research results.

Research on Design of MUH Attitude Stability Augmentation Control System

Science.gov (United States)

Fan, Shigang

2017-09-01

Attitude stability augmentation control system with a lower cost need to be designed so that MUH (Mini Unmanned Helicopter) can adapt to different types of geographic environment and fly steadily although the weather may be bad. Attitude feedback was calculated mainly by filtering estimation within attitude acquisition module in this system. Stability augmentation can be improved mainly by PI. This paper will depict running principle and designing process of MUH attitude stability augmentation control system and algorithm that is considered as an important part in this system.

NSRL 200 MeV linac beam energy stabilization system

International Nuclear Information System (INIS)

Huang Guirong; Pei Yuanji; Dong Sai

2001-01-01

By using the computer image processing technology and RF phase auto-shifting system, the ESS (Energy Stabilization System) was applied to 200 MeV Linac. the ESS adjusts beam energy automatically in a range of +-4 MeV. After adjustment beam energy stability is improved to +-6%

On Robust Stability of Systems of Differential-Algebraic Equations

Directory of Open Access Journals (Sweden)

A. Shcheglova

2016-06-01

The sufficient conditions of robust stability for index-one and index-two systems are obtained. We use the values of real and complex stability radii obtained for system of ordinary differential equations solved with respect to the derivatives. We consider the example illustrating the obtained results.

Electrostatic stabilizer for a passive magnetic bearing system

Science.gov (United States)

Post, Richard F.

2015-11-24

Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

Simplified Stability Criteria for Delayed Neutral Systems

Directory of Open Access Journals (Sweden)

Xinghua Zhang

2014-01-01

Full Text Available For a class of linear time-invariant neutral systems with neutral and discrete constant delays, several existing asymptotic stability criteria in the form of linear matrix inequalities (LMIs are simplified by using matrix analysis techniques. Compared with the original stability criteria, the simplified ones include fewer LMI variables, which can obviously reduce computational complexity. Simultaneously, it is theoretically shown that the simplified stability criteria and original ones are equivalent; that is, they have the same conservativeness. Finally, a numerical example is employed to verify the theoretic results investigated in this paper.

Synchrophasor-Assisted Prediction of Stability/Instability of a Power System

Science.gov (United States)

Saha Roy, Biman Kumar; Sinha, Avinash Kumar; Pradhan, Ashok Kumar

2013-05-01

This paper presents a technique for real-time prediction of stability/instability of a power system based on synchrophasor measurements obtained from phasor measurement units (PMUs) at generator buses. For stability assessment the technique makes use of system severity indices developed using bus voltage magnitude obtained from PMUs and generator electrical power. Generator power is computed using system information and PMU information like voltage and current phasors obtained from PMU. System stability/instability is predicted when the indices exceeds a threshold value. A case study is carried out on New England 10-generator, 39-bus system to validate the performance of the technique.

Power system stabilization by SMES using current-fed pwm power conditioner

International Nuclear Information System (INIS)

Ishikawa, T.; Akita, S.; Taniguchi, H.; Kosho, S.; Tanaka, T.

1988-01-01

A superconducting magnetic energy storage (SMES) unit, consisted of superconducting coil and AC/DC power conditioner, can be used to suppress various kinds of instability that may cause service interruption in electric power system as it has high controllability of input/output electric power. Power system stabilizing ability of SMES has been examined experimentally by using model power system and small SMES unit. Current-fed PWM power conditioner was used to obtain maximum stabilizing effect by controlling active and reactive power simultaneously and independently. Power conditioner configuration, operating characteristics and control scheme for power system stabilization are also described. Results from experiments show the effectiveness of SMES on power system stabilization

Improvement of the transient stability using SFCL in Korean power systems

International Nuclear Information System (INIS)

Hwang, Intae; Lee, Seung Ryul; Seo, Sangsoo; Yoon, Jaeyoung; Kim, Chul-Hwan

2013-01-01

Highlights: •In Korea, the Special Protection System is applied for protecting the power system. •Hybrid SFCL is protecting the power system from viewpoint of the transient stability. •Basic hybrid SFCL system cannot recover during the auto-reclosing operation. •This paper performs analysis of transient stability using the novel hybrid SFCL. -- Abstract: This paper proposed a novel hybrid SFCL system for the enhancement of the transient stability in Korean power transmission system with auto-reclosing operation. The proposed SFCL system has an operation mechanism that the current limiting impedance is eliminated from the power system in a fault clearing time for the enhancement of the transient stability. Also, the system can cover the auto-reclosing operation of the transmission power system. This study analyzed an improvement of the special protection system by applying the proposed SFCL system to real power system in Korea

Stabilization of third-order bilinear systems using constant controls

Directory of Open Access Journals (Sweden)

A. E. Golubev

2014-01-01

Full Text Available This paper deals with the zero equilibrium stabilization for dynamical systems that have control input singularities. A dynamical system with scalar control input is called nonregular if the coefficient of input becomes null on a subset of the phase space that contains the origin. One of the classes of nonregular dynamical systems is represented by bilinear systems. In case of second-order bilinear systems the necessary and sufficient conditions for the zero equilibrium stabilizability are known in the literature. However, in general case the stabilization problem in the presence of control input singularities has not been solved yet.In this note we solve the problem of the zero equilibrium stabilization for the third-order bilinear dynamical systems given in a canonical form. The solution is found in the class of constant controls. The necessary and sufficient conditions are obtained for the zero equilibrium stabilizability of the bilinear systems in question.The dependence of the zero equilibrium stabilizability on system parameter values is analyzed. The general criteria of stabilizability by means of constant controls are given for the bilinear systems in question. In case when all the system parameters have nonzero values the necessary and sufficient stabilizability conditions are proved. The case when some of the parameters are equal to zero is also considered.Further research can be focused on extending the obtained results to a higher-order case of bilinear and affine dynamical systems. The solution of the considered stabilization problem should also be found not only within constant controls but also in a class of state feedbacks, particularly, in the case when stabilizing constant control does not exist.One of the potential application areas for the obtained theoretical results is automatic control of technical plants like unmanned aerial vehicles and mobile robots.

Stability of neutral type descriptor system with mixed delays

International Nuclear Information System (INIS)

Li Hong; Li Houbiao; Zhong Shouming

2007-01-01

In this paper, the stability problems of general neutral type descriptor system with mixed delays are considered. Some new delay-independent stability and robust stability criteria, which are simpler and less conservative than existing results, are derived in terms of the stability of a new operator I and linear matrix inequalities (LMIs). Therefore, criteria can be easily checked by utilizing the Matlab LMI toolbox

Robust stability bounds for multi-delay networked control systems

Science.gov (United States)

Seitz, Timothy; Yedavalli, Rama K.; Behbahani, Alireza

2018-04-01

In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.

Power system stability enhancement using facts controllers: a review

International Nuclear Information System (INIS)

Abido, M. A

2009-01-01

In recent years, power demand has increased substantially while the expansion of power generation and transmission has been severely limited due to limited resources and environmental restrictions. As a consequence, some transmission lines are heavily loaded and the system stability becomes a power transfer-limiting factor. Flexible AC transmission systems (FACTS) controllers have been mainly used for solving various power system steady state control problems. However, recent studies reveal that FACTS controllers could be employed to enhance power system stability in addition to their main function of power flow control. The literature shows an increasing interest in this subject for the last two decades, where the enhancement of system stability using FACTS controllers has been extensively investigated. This paper presents a comprehensive review on the research and developments in the power system stability enhancement using FACTS damping controllers. Several technical issues related to FACTS installations have been highlighted and performance comparison of different FACTS controllers has been discussed. In addition, some of the utility experience, real-world installations, and semiconductor technology development have been reviewed and summarized. Applications of FACTS to other power system studies have also been discussed. About two hundred twenty seven research publications have been classified and appended for a quick reference. (author)

On a program manifold’s stability of one contour automatic control systems

Directory of Open Access Journals (Sweden)

Zumatov S. S.

2017-12-01

Full Text Available Methodology of analysis of stability is expounded to the one contour systems automatic control feedback in the presence of non-linearities. The methodology is based on the use of the simplest mathematical models of the nonlinear controllable systems. Stability of program manifolds of one contour automatic control systems is investigated. The sufficient conditions of program manifold’s absolute stability of one contour automatic control systems are obtained. The Hurwitz’s angle of absolute stability was determined. The sufficient conditions of program manifold’s absolute stability of control systems by the course of plane in the mode of autopilot are obtained by means Lyapunov’s second method.

Stability analysis of linear switching systems with time delays

International Nuclear Information System (INIS)

Li Ping; Zhong Shouming; Cui Jinzhong

2009-01-01

The issue of stability analysis of linear switching system with discrete and distributed time delays is studied in this paper. An appropriate switching rule is applied to guarantee the stability of the whole switching system. Our results use a Riccati-type Lyapunov functional under a condition on the time delay. So, switching systems with mixed delays are developed. A numerical example is given to illustrate the effectiveness of our results.

A Methodology to Efficiently Compare Operating System Stability

NARCIS (Netherlands)

van der Kouwe, E.; Giuffrida, C.; Ghitulete, R.; Tanenbaum, A.S.

2015-01-01

Despite decades of advances in software engineering, operating systems (OSes) are still plagued by crashes due to software faults, calling for techniques to improve OS stability when faults occur. Evaluating such techniques requires a way to compare the stability of different OSes that is both

Stability Analysis of Interconnected Fuzzy Systems Using the Fuzzy Lyapunov Method

Directory of Open Access Journals (Sweden)

Ken Yeh

2010-01-01

Full Text Available The fuzzy Lyapunov method is investigated for use with a class of interconnected fuzzy systems. The interconnected fuzzy systems consist of J interconnected fuzzy subsystems, and the stability analysis is based on Lyapunov functions. Based on traditional Lyapunov stability theory, we further propose a fuzzy Lyapunov method for the stability analysis of interconnected fuzzy systems. The fuzzy Lyapunov function is defined in fuzzy blending quadratic Lyapunov functions. Some stability conditions are derived through the use of fuzzy Lyapunov functions to ensure that the interconnected fuzzy systems are asymptotically stable. Common solutions can be obtained by solving a set of linear matrix inequalities (LMIs that are numerically feasible. Finally, simulations are performed in order to verify the effectiveness of the proposed stability conditions in this paper.

A digital intensity stabilization system for HeNe laser

Science.gov (United States)

Wei, Zhimeng; Lu, Guangfeng; Yang, Kaiyong; Long, Xingwu; Huang, Yun

2012-02-01

A digital intensity stabilization system for HeNe laser is developed. Based on a switching power IC to design laser power supply and a general purpose microcontroller to realize digital PID control, the system constructs a closed loop to stabilize the laser intensity by regulating its discharge current. The laser tube is made of glass ceramics and its integrated structure is steady enough to eliminate intensity fluctuations at high frequency and attenuates all intensity fluctuations, and this makes it easy to tune the control loop. The control loop between discharge current and photodiode voltage eliminates the long-term drifts. The intensity stability of the HeNe laser with this system is 0.014% over 12 h.

Decentralized linear quadratic power system stabilizers for multi ...

Indian Academy of Sciences (India)

Linear quadratic stabilizers are well-known for their superior control capabilities when compared to the conventional lead–lag power system stabilizers. However, they have not seen much of practical importance as the state variables are generally not measurable; especially the generator rotor angle measurement is not ...

INERTIAL TECHNOLOGIES IN SYSTEMS FOR STABILIZATION OF GROUND VEHICLES EQUIPMENT

Directory of Open Access Journals (Sweden)

Olha Sushchenko

2016-12-01

Full Text Available Purpose: The vibratory inertial technology is a recent modern inertial technology. It represents the most perspective approach to design of inertial sensors, which can be used in stabilization and tracking systems operated on vehicles of the wide class. The purpose of the research is to consider advantages of this technology in comparison with laser and fiber-optic ones. Operation of the inertial sensors on the ground vehicles requires some improvement of the Coriolis vibratory gyroscope with the goal to simplify information processing, increase reliability, and compensate bias. Methods: Improvement of the Coriolis vibratory gyroscope includes introducing of the phase detector and additional excitation unit. The possibility to use the improved Coriolis vibratory gyroscope in the stabilization systems operated on the ground vehicles is shown by means of analysis of gyroscope output signal. To prove efficiency of the Coriolis vibratory gyroscope in stabilization system the simulation technique is used. Results: The scheme of the improved Coriolis vibratory gyroscope including the phase detector and additional excitation unit is developed and analyzed. The way to compensate bias is determined. Simulation of the stabilization system with the improved Coriolis vibratory gyroscope is carried out. Expressions for the output signals of the improved Coriolis vibratory gyroscope are derived. The error of the output signal is estimated and the possibility to use the modified Coriolis vibratory gyroscope in stabilization systems is proved. The results of stabilization system simulation are given. Their analysis is carried out. Conclusions: The represented results prove efficiency of the proposed technical decisions. They can be useful for design of stabilization platform with instrumental equipment operated on moving vehicles of the wide class.

Robust Stability and Stabilization of Interval Uncertain Descriptor Fractional-Order Systems with the Fractional-Order α: The 1≤α<2 Case

Directory of Open Access Journals (Sweden)

Yuanhua Li

2015-01-01

Full Text Available Stability and stabilization of fractional-order interval system is investigated. By adding parameters to linear matrix inequalities, necessary and sufficient conditions for stability and stabilization of the system are obtained. The results on stability check for uncertain FO-LTI systems with interval coefficients of dimension n only need to solve one 4n-by-4n LMI. Numerical examples are presented to shown the effectiveness of our results.

On the stability of some systems of exponential difference equations

Directory of Open Access Journals (Sweden)

N. Psarros

2018-01-01

Full Text Available In this paper we prove the stability of the zero equilibria of two systems of difference equations of exponential type, which are some extensions of an one-dimensional biological model. The stability of these systems is investigated in the special case when one of the eigenvalues is equal to -1 and the other eigenvalue has absolute value less than 1, using centre manifold theory. In addition, we study the existence and uniqueness of positive equilibria, the attractivity and the global asymptotic stability of these equilibria of some related systems of difference equations.

Optimal boundary control and boundary stabilization of hyperbolic systems

CERN Document Server

Gugat, Martin

2015-01-01

This brief considers recent results on optimal control and stabilization of systems governed by hyperbolic partial differential equations, specifically those in which the control action takes place at the boundary.  The wave equation is used as a typical example of a linear system, through which the author explores initial boundary value problems, concepts of exact controllability, optimal exact control, and boundary stabilization.  Nonlinear systems are also covered, with the Korteweg-de Vries and Burgers Equations serving as standard examples.  To keep the presentation as accessible as possible, the author uses the case of a system with a state that is defined on a finite space interval, so that there are only two boundary points where the system can be controlled.  Graduate and post-graduate students as well as researchers in the field will find this to be an accessible introduction to problems of optimal control and stabilization.

Stability of large scale interconnected dynamical systems

International Nuclear Information System (INIS)

Akpan, E.P.

1993-07-01

Large scale systems modelled by a system of ordinary differential equations are considered and necessary and sufficient conditions are obtained for the uniform asymptotic connective stability of the systems using the method of cone-valued Lyapunov functions. It is shown that this model significantly improves the existing models. (author). 9 refs

Impact of PSS and SVC on the Power System Transient Stability

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Mohammed Omar Benaissa

2017-06-01

Full Text Available The Static Var Compensator (SVC is used to improve the stability of the power system because of its role in injecting or absorbing the reactive power in the electrical transmission lines. The Power System Stabilizer (PSS is also a control device which ensures maximum power transfer and thus the stability of the power system enhancement. The PSS has been widely used to damp electromechanical oscillations occur in power systems. If no adequate damping is available, the oscillations will increase leading to instability. The present work is an original contribution to the problem of transient stability in the electrical power system, the authors have made some efforts to illustrate the flexibility and the importance of inserting the SVC alone or with the PSS the fact that maintain the characteristics of the system within acceptable limits in a very short time. The results show that the system has been developed successfully in terms of transient stability in a bi-machine transmission system only with the presence of PSS when a single-phase fault has been occurred, while the presence of SVC is more than essential when a three-phase fault is occurred.

14 CFR 29.672 - Stability augmentation, automatic, and power-operated systems.

Science.gov (United States)

2010-01-01

... power-operated systems. 29.672 Section 29.672 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Construction Control Systems § 29.672 Stability augmentation, automatic, and power-operated systems. If the functioning of stability augmentation or other automatic or power-operated system is necessary to show...

14 CFR 27.672 - Stability augmentation, automatic, and power-operated systems.

Science.gov (United States)

2010-01-01

... power-operated systems. 27.672 Section 27.672 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Construction Control Systems § 27.672 Stability augmentation, automatic, and power-operated systems. If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show...

Theoretical bases on thermal stability of layered metallic systems

International Nuclear Information System (INIS)

Kadyrzhanov, K.K.; Rusakov, V.S.; Turkebaev, T.Eh.; Zhankadamova, A.M.; Ensebaeva, M.Z.

2003-01-01

The paper is dedicated to implementation of the theoretical bases for layered metallic systems thermal stabilization. The theory is based on the stabilization mechanism expense of the intermediate two-phase field formation. As parameters of calculated model are coefficients of mutual diffusion and inclusions sizes of generated phases in two-phase fields. The stabilization time dependence for beryllium-iron (Be (1.1 μm)-Fe(5.5 μm)) layered system from iron and beryllium diffusion coefficients, and inclusions sizes is shown as an example. Conclusion about possible mechanisms change at transition from microscopic consideration to the nano-crystal physics level is given

Stability of a slotted ALOHA system with capture effect

Science.gov (United States)

Onozato, Yoshikuni; Liu, Jin; Noguchi, Shoichi

1989-02-01

The stability of a slotted ALOHA system with capture effect is investigated under a general communication environment where terminals are divided into two groups (low-power and high-power) and the capture effect is modeled by capture probabilities. An approximate analysis is developed using catastrophe theory, in which the effects of system and user parameters on the stability are characterized by the cusp catastrophe. Particular attention is given to the low-power group, since it must bear the strain under the capture effect. The stability conditions of the two groups are given explicitly by bifurcation sets.

Stabilization and tracking controller for a class of nonlinear discrete-time systems

International Nuclear Information System (INIS)

Sharma, B.B.; Kar, I.N.

2011-01-01

Highlights: → We present recursive design of stabilizing controller for nonlinear discrete-time systems. → Problem of stabilizing and tracking control of single link manipulator system is addressed. → We extend the proposed results to output tracking problems. → The proposed methodology is applied satisfactorily to discrete-time chaotic maps. - Abstract: In this paper, stabilization and tracking control problem for parametric strict feedback class of discrete time systems is addressed. Recursive design of control function based on contraction theory framework is proposed instead of traditional Lyapunov based method. Explicit structure of controller is derived for the addressed class of nonlinear discrete-time systems. Conditions for exponential stability of system states are derived in terms of controller parameters. At each stage of recursive procedure a specific structure of Jacobian matrix is ensured so as to satisfy conditions of stability. The closed loop dynamics in this case remains nonlinear in nature. The proposed algorithm establishes global stability results in quite a simple manner as it does not require formulation of error dynamics. Problem of stabilization and output tracking control in case of single link manipulator system with actuator dynamics is analyzed using the proposed strategy. The proposed results are further extended to stabilization of discrete time chaotic systems. Numerical simulations presented in the end show the effectiveness of the proposed approach.

STABILITY SYSTEMS VIA HURWITZ POLYNOMIALS

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BALTAZAR AGUIRRE HERNÁNDEZ

2017-01-01

Full Text Available To analyze the stability of a linear system of differential equations  ẋ = Ax we can study the location of the roots of the characteristic polynomial pA(t associated with the matrix A. We present various criteria - algebraic and geometric - that help us to determine where the roots are located without calculating them directly.

Transient stability risk assessment of power systems incorporating wind farms

DEFF Research Database (Denmark)

Miao, Lu; Fang, Jiakun; Wen, Jinyu

2013-01-01

fed induction generator has been established. Wind penetration variation and multiple stochastic factors of power systems have been considered. The process of transient stability risk assessment based on the Monte Carlo method has been described and a comprehensive risk indicator has been proposed......Large-scale wind farm integration has brought several aspects of challenges to the transient stability of power systems. This paper focuses on the research of the transient stability of power systems incorporating with wind farms by utilizing risk assessment methods. The detailed model of double....... An investigation has been conducted into an improved 10-generator 39-bus system with a wind farm incorporated to verify the validity and feasibility of the risk assessment method proposed....

Stability analysis of transmission system with high penetration of distributed generation

Energy Technology Data Exchange (ETDEWEB)

Reza, M.

2006-12-21

Nowadays, interest in generating electricity using decentralized generators of relatively small scale ('distributed generation', DG) is increasing. This work deals with the impact of implementing DG on the transmission system transient stability, with the emphasis on a potential transition from a 'vertical power system' to a 'horizontal power system. A problem in power systems is maintaining synchronous operation of all (centralized) synchronous machines. This stability problem associated is called rotor angle stability. In this work, the impact of the DG implementation on this is investigated. The impact of DG levels on the system transient stability when the increasing DG level is followed by a reduction of centralized generators in service resulting in a 'vertical to horizontal' transformation of the power system is also investigated. Furthermore, a stochastic analysis is used to study the transient stability of the power systems. The results show that including the stochastic behavior of DG leads to a more complete and detailed view of the system performance. Finally, the situation when the power system is pushed towards a scenario, where DG penetration reaches a level that covers the total load of the original power system (100% DG level) is investigated. The research performed in this work indicates that from the transmission system stability point of view, if higher DG penetration levels are coming up, sufficient inertia and voltage support must be installed. Furthermore, one should be aware of the fact that the system behaves stochastically, especially with DG. To a certain extent regional balancing of power can be performed by local voltage control.

Development of a terminal voltage stabilization system for the FOTIA ...

Indian Academy of Sciences (India)

Abstract. A terminal voltage stabilization system for the folded tandem ion accelerator (FOTIA) was developed and is in continuous use. The system achieves good voltage stabilization, eliminates ground loops and noise interference. It incorporates a correcting circuit for compensating the mains frequency variations in the ...

Assessing Power System Stability Following Load Changes and Considering Uncertainty

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D. V. Ngo

2018-04-01

Full Text Available An increase in load capacity during the operation of a power system usually causes voltage drop and leads to system instability, so it is necessary to monitor the effect of load changes. This article presents a method of assessing the power system stability according to the load node capacity considering uncertainty factors in the system. The proposed approach can be applied to large-scale power systems for voltage stability assessment in real-time.

ESTUDIOS TRANSCULTURALES DEL BURNOUT: LOS ESTUDIOS TRANSCULTURALES BRASIL-ESPAÑA

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Macarena Gálvez Herrer

2003-07-01

Full Text Available Los estudios transculturales no son un ejercicio secundario y complementario en el estudio de la psicología; un modelo antropológico de la conducta humana obliga a plantear que las variables culturales no son secundarias sino primarias. Por estas razones el estudio del “burnout†o desgaste profesional puede profundizarse mediante la utilización de los métodos transculturales. No es suficiente con la simple comparación de resultados, sino que es necesario buscar instrumentos propios de cada cultura y establecer la comparación no sólo del síndrome de desgaste profesional sino de todos los diferentes elementos del proceso. El trabajo presentado establece las bases teóricas de este planteamiento, y expone, mediante un ejemplo, algunas de las vías posibles para una psicología transcultural del burnout.

Adaptive Integral Sliding Mode Stabilization of Nonholonomic Drift-Free Systems

Directory of Open Access Journals (Sweden)

Waseem Abbasi

2016-01-01

Full Text Available This article presents adaptive integral sliding mode control algorithm for the stabilization of nonholonomic drift-free systems. First the system is transformed, by using input transform, into a special structure containing a nominal part and some unknown terms which are computed adaptively. The transformed system is then stabilized using adaptive integral sliding mode control. The stabilizing controller for the transformed system is constructed that consists of the nominal control plus a compensator control. The compensator control and the adaptive laws are derived on the basis of Lyapunov stability theory. The proposed control algorithm is applied to three different nonholonomic drift-free systems: the unicycle model, the front wheel car model, and the mobile robot with trailer model. The controllability Lie algebra of the unicycle model contains Lie brackets of depth one, the model of a front wheel car contains Lie brackets of depths one and two, and the model of a mobile robot with trailer contains Lie brackets of depths one, two, and three. The effectiveness of the proposed control algorithm is verified through numerical simulations.

Uniform stability for time-varying infinite-dimensional discrete linear systems

International Nuclear Information System (INIS)

Kubrusly, C.S.

1988-09-01

Stability for time-varying discrete linear systems in a Banach space is investigated. On the one hand, it established a fairly complete collection of necessary and sufficient conditions for uniform asymptotic equistability for input-free systems. This includes uniform and strong power equistability, and uniform and strong l p -equistability, among other technical conditions which also play essential role in stability theory. On other hand, it is shown that uniform asymptotic equistability for input-free systems is equivalent to each of the following concepts of uniform stability for forced systems: l p -input l p -state, c o -input c o -state, bounded-input bounded-state, l p>1 -input bounded-state, c sub (o)-input bounded-state, and convergent-input bounded-state; which are also equivalent to their nonuniform counterparts. For time-varying convergent systems, the above is also equivalent to convergent-input convergent-state stability. The proofs presented here are all ''elementary'' in the sense that they are based essentially only on the Banach-Steinhaus theorem. (autor) [pt

Stability design considerations for mirror support systems in ICF lasers

International Nuclear Information System (INIS)

Tietbohl, G.L.; Sommer, S.C.

1996-10-01

Some of the major components of laser systems used for Inertial Confinement Fusion (ICF) are the large aperture mirrors which direct the path of the laser. These mirrors are typically supported by systems which consist of mirror mounts, mirror enclosures, superstructures, and foundations. Stability design considerations for the support systems of large aperture mirrors have been developed based on the experience of designing and evaluating similar systems at the Lawrence Livermore National Laboratory (LLNL). Examples of the systems developed at LLNL include Nova, the Petawatt laser, Beamlet, and the National Ignition Facility (NIF). The structural design of support systems of large aperture mirrors has typically been controlled by stability considerations in order for the large laser system to meet its performance requirements for alignment and positioning. This paper will discuss the influence of stability considerations and will provide guidance on the structural design and evaluation of mirror support systems in ICF lasers so that this information can be used on similar systems

Microprocessor system for temperature regulation and stabilization

International Nuclear Information System (INIS)

Nguyen Nhi Dien; Rodionov, K.G.

1989-01-01

Microprocessor based system for temperature regulation and stabilization of an operation external object is described. The system has the direct current amplifier working according to modulator-demodulator principle. The overal gain is 100, 1000, 2000. The maximum output signal is ±10 V. The power amplifier is a thyristor one and its line voltage is 220 V, 50 Hz. The output power is 0-2 kVA. The microcontroller has a remote display terminal. Data input is 8 and data output is one. Input and output voltage is ±(0-10) V. The preselection time for stabilization is within 1 s - 18 h. The program algorithm is given. 5 figs.; 1 tab

System specification for the plutonium stabilization and packaging system

International Nuclear Information System (INIS)

1996-01-01

This document describes functional design requirements for the Plutonium Stabilization and Packaging System (Pu SPS), as required by DOE contract DE-AC03-96SF20948 through contract modification 9 for equipment in Building 707 at Rocky Flats Environmental Technology Site (RFETS)

Indefinite damping in mechanical systems and gyroscopic stabilization

DEFF Research Database (Denmark)

Kliem, Wolfhard; Pommer, Christian

2009-01-01

This paper deals with gyroscopic stabilization of the unstable system Mx + D(x) over dot + K-x = 0, with positive definite mass and stiffness matrices M and K, respectively, and an indefinite damping matrix D. The main question if for which skew-symmetric matrices G the system Mx (D+ G)(x) over dot...... + K-x = 0 can become stable? After investigating special cases we find an appropriat solution of the Lyapunov matrix equation for the general case. Examples show the deviation of the stability limit found by the Lyapunov method from the exact value....

Transient stability probability evaluation of power system incorporating with wind farm and SMES

DEFF Research Database (Denmark)

Fang, Jiakun; Miao, Lu; Wen, Jinyu

2013-01-01

Large scale renewable power generation brings great challenges to the power system operation and stabilization. Energy storage is one of the most important technologies to face the challenges. This paper proposes a method for transient stability probability evaluation of power system with wind farm...... and SMES. Firstly, a modified 11-bus test system with both wind farm and SMES has been implemented. The wind farm is represented as a doubly fed induction generator (DFIG). Then a stochastic-based approach to evaluate the probabilistic transient stability index of the power system is presented. Uncertain...... the probability indices. With the proposed method based on Monte-Carlo simulation and bisection method, system stability is "measured". Quantitative relationship of penetration level, SMES coil size and system stability is established. Considering the stability versus coil size to be the production curve...

Simulation for transient stability study of the Taiwan power system - a nuclear majority system

International Nuclear Information System (INIS)

Huang, J.C.C.

1984-01-01

A transient stability program was developed for the Taiwan Power Company, which has a high proportion of nuclear generation in its power system. This program offers a new territory to investigate nuclear plant effects on the power system transient stability. This program also provides a high speed tool for the Taipower system operational planning. A generalized procedure of synchronous machine modeling for a large-scale stability study is presented. The merits and weaknesses of machine modeling can be comprehended through each item of this procedure. Three types of nonlinear synchronous machine modeling implemented into this stability program are derived by following this procedure. A robust subroutine was derived to perform the fourth order Runge-Kutta integration method, making the software programming neat and systematical. For simulating the nuclear plant influence on the system, this program implemented an additional four functions: load-limit operation simulated by a low-value gate in the governor model, bypass valve capacity monitored by sending out a warning message, rotor overspeed protection relay, and generator anti-motoring relay

Learning and Understanding System Stability Using Illustrative Dynamic Texture Examples

Science.gov (United States)

Liu, Huaping; Xiao, Wei; Zhao, Hongyan; Sun, Fuchun

2014-01-01

System stability is a basic concept in courses on dynamic system analysis and control for undergraduate students with computer science backgrounds. Typically, this was taught using a simple simulation example of an inverted pendulum. Unfortunately, many difficult issues arise in the learning and understanding of the concepts of stability,…

Stability and boundary stabilization of 1-D hyperbolic systems

CERN Document Server

Bastin, Georges

2016-01-01

This monograph explores the modeling of conservation and balance laws of one-dimensional hyperbolic systems using partial differential equations. It presents typical examples of hyperbolic systems for a wide range of physical engineering applications, allowing readers to understand the concepts in whichever setting is most familiar to them. With these examples, it also illustrates how control boundary conditions may be defined for the most commonly used control devices. The authors begin with the simple case of systems of two linear conservation laws and then consider the stability of systems under more general boundary conditions that may be differential, nonlinear, or switching. They then extend their discussion to the case of nonlinear conservation laws and demonstrate the use of Lyapunov functions in this type of analysis. Systems of balance laws are considered next, starting with the linear variety before they move on to more general cases of nonlinear ones. They go on to show how the problem of boundary...

General Output Feedback Stabilization for Fractional Order Systems: An LMI Approach

Directory of Open Access Journals (Sweden)

Yiheng Wei

2014-01-01

Full Text Available This paper is concerned with the problem of general output feedback stabilization for fractional order linear time-invariant (FO-LTI systems with the fractional commensurate order 0<α<2. The objective is to design suitable output feedback controllers that guarantee the stability of the resulting closed-loop systems. Based on the slack variable method and our previous stability criteria, some new results in the form of linear matrix inequality (LMI are developed to the static and dynamic output feedback controllers synthesis for the FO-LTI system with 0<α<1. Furthermore, the results are extended to stabilize the FO-LTI systems with 1≤α<2. Finally, robust output feedback control is discussed. Numerical examples are given to illustrate the effectiveness of the proposed design methods.

Predictor-based stabilization for chained form systems with input time delay

Directory of Open Access Journals (Sweden)

Mnif Faïçal

2016-12-01

Full Text Available This note addresses the stabilization problem of nonlinear chained-form systems with input time delay. We first employ the so-called σ-process transformation that renders the feedback system under a linear form. We introduce a particular transformation to convert the original system into a delay-free system. Finally, we apply a state feedback control, which guarantees a quasi-exponential stabilization to all the system states, which in turn converge exponentially to zero. Then we employ the so-called -type control to achieve a quasi-exponential stabilization of the subsequent system. A simulation example illustrated on the model of a wheeled mobile robot is provided to demonstrate the effectiveness of the proposed approach.

Estudios sobre postmodernidad y estudios culturales: ¿sinónimos?

Directory of Open Access Journals (Sweden)

Dr. Roberto A. Follari

2000-01-01

Full Text Available La postmodernidad exige para ser comprendida una dimensión sociohistórica y otra filosófica que le resulta irrenunciables. También hay una serie de fenómenos propiamente culturales, que son los que los denominados "estudios culturales" (G. Canclini. M. Barbero, etc. han asumido en Latinoamérica. Tales estudios han aportado una descripción de fenómenos nuevos, que no son analizados por ningún otro discurso teórico (tribus urbanas, identidades lábiles, influencia de los medios en los nuevos estilos de consumo, etc.. Con ello se da cuenta de parte de la cuestión postmodernidad, pero sin dudase deja fuera otras: lo filosófico y aún lo social y lo político quedan fuera de esa especie de antropología del presente. Por lo tanto, un enfoque integral de lo postmoderno incluye los estudios culturales, pero está lejos de limitarse a ellos.

Morocco; Financial System Stability Assessment: Update

OpenAIRE

International Monetary Fund

2008-01-01

This paper presents an update to the Financial System Stability Assessment on Morocco. Major reforms have been achieved since the 2002 Financial Sector Assessment Program (FSAP) within a policy of actively promoting economic and financial sector opening. The 2002 FSAP recommendations have been largely implemented. Although the financial system is stable and considerably more robust than in the past, the liberalization of capital flows and increased exchange rate flexibility present challenges...

Stability Analysis and Stabilization of T-S Fuzzy Delta Operator Systems with Time-Varying Delay via an Input-Output Approach

Directory of Open Access Journals (Sweden)

Zhixiong Zhong

2013-01-01

Full Text Available The stability analysis and stabilization of Takagi-Sugeno (T-S fuzzy delta operator systems with time-varying delay are investigated via an input-output approach. A model transformation method is employed to approximate the time-varying delay. The original system is transformed into a feedback interconnection form which has a forward subsystem with constant delays and a feedback one with uncertainties. By applying the scaled small gain (SSG theorem to deal with this new system, and based on a Lyapunov Krasovskii functional (LKF in delta operator domain, less conservative stability analysis and stabilization conditions are obtained. Numerical examples are provided to illustrate the advantages of the proposed method.

Competition and system stability -- The reward and the penalty

International Nuclear Information System (INIS)

Mansour, Y.

2000-01-01

The business protocols and rules of the competitive electricity market are resulting in fragmentation of the historical vertically integrated structures. Electric services are offered at either cost or market-based prices depending on their type and the level of competition in a particular product. System stabilizing measures are essential for maintaining system security, yet their value is either underestimated or not understood. This paper describes practical methods to quantify the value of some of the stabilizing measures and ways to ensure maintaining the dynamic security of the power systems through business procedures and monetary sanctions

Transient Stability Improvement of IEEE 9 Bus System Using Power World Simulator

Directory of Open Access Journals (Sweden)

Kaur Ramandeep

2016-01-01

Full Text Available The improvement of transient stability of power system was one of the most challenging research areas in power engineer.The main aim of this paper was transient stability analysis and improvement of IEEE 9 bus system. These studies were computed using POWER WORLD SIMULATOR. The IEEE 9 bus system was modelled in power world simulator and load flow studies were performed to determine pre-fault conditions in the system using Newton-Raphson method. The transient stability analysis was carried out using Runga method during three-phase balanced fault. For the improvement transient stability, the general methods adopted were fast acting exciters, FACT devices and addition of parallel transmission line. These techniques play an important role in improving the transient stability, increasing transmission capacity and damping low frequency oscillations.

A real-time BWR stability measurement system

International Nuclear Information System (INIS)

March-Leuba, J.; King, W.T.

1988-01-01

This paper describes the characteristics of a portable, real-time system used for nonperturbational measurements of stability in boiling water reactors. The algorithm used in this system estimates the closed-loop asymptotic decay ratio using only the naturally occurring neutron noise and it is based on the univariate autoregressive methodology. (author)

Tritium systems test assembly stabilization

International Nuclear Information System (INIS)

Jasen, William G.; Michelotti, Roy A.; Anast, Kurt R.; Tesch, Charles

2004-01-01

The Tritium Systems Test Assembly (TSTA) was a facility dedicated to tritium technology Research and Development (R and D) primarily for future fusion power reactors. The facility was conceived in mid 1970's, operations commenced in early 1980's, stabilization and deactivation began in 2000 and were completed in 2003. The facility will remain in a Surveillance and Maintenance (S and M) mode until the Department of Energy (DOE) funds demolition of the facility, tentatively in 2009. A safe and stable end state was achieved by the TSTA Facility Stabilization Project (TFSP) in anticipation of long term S and M. At the start of the stabilization project, with an inventory of approximately 140 grams of tritium, the facility was designated a Hazard Category (HC) 2 Non-Reactor Nuclear facility as defined by US Department of Energy standard DOE-STD-1027-92 (1997). The TSTA facility comprises a laboratory area, supporting rooms, offices and associated laboratory space that included more than 20 major tritium handling systems. The project's focus was to reduce the tritium inventory by removing bulk tritium, tritiated water wastes, and tritium-contaminated high-inventory components. Any equipment that remained in the facility was stabilized in place. All of the gloveboxes and piping were rendered inoperative and vented to atmosphere. All equipment, and inventoried tritium contamination, remaining in the facility was left in a safe-and-stable state. The project used the End Points process as defined by the DOE Office of Environmental Management (web page http://www.em.doe.- gov/deact/epman.htmtlo) document and define the end state required for the stabilization of TSTA Facility. The End Points process added structure that was beneficial through virtually all phases of the project. At completion of the facility stabilization project the residual tritium inventory was approximately 3,000 curies, considerably less than the 1.6-gram threshold for a HC 3 facility. TSTA is now

Stability of position control system in JIPP T-II

International Nuclear Information System (INIS)

Sakurai, Keiichi; Tanahashi, Shygo

1980-01-01

Computations and experiments on the stability of a feedback control system for maintaining a plasma column in equilibrium are described. The time response of the displacement of the plasma to the desired position is examined by solving the equation of motion of the plasma column. We show that the stability of the feedback control system is improved by using an additional term which represents the shift velocity of the plasma column. (author)

Mittag-Leffler Stability Theorem for Fractional Nonlinear Systems with Delay

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S. J. Sadati

2010-01-01

Full Text Available Fractional calculus started to play an important role for analysis of the evolution of the nonlinear dynamical systems which are important in various branches of science and engineering. In this line of taught in this paper we studied the stability of fractional order nonlinear time-delay systems for Caputo's derivative, and we proved two theorems for Mittag-Leffler stability of the fractional nonlinear time delay systems.

Sensitivity of system stability to model structure

Science.gov (United States)

Hosack, G.R.; Li, H.W.; Rossignol, P.A.

2009-01-01

A community is stable, and resilient, if the levels of all community variables can return to the original steady state following a perturbation. The stability properties of a community depend on its structure, which is the network of direct effects (interactions) among the variables within the community. These direct effects form feedback cycles (loops) that determine community stability. Although feedback cycles have an intuitive interpretation, identifying how they form the feedback properties of a particular community can be intractable. Furthermore, determining the role that any specific direct effect plays in the stability of a system is even more daunting. Such information, however, would identify important direct effects for targeted experimental and management manipulation even in complex communities for which quantitative information is lacking. We therefore provide a method that determines the sensitivity of community stability to model structure, and identifies the relative role of particular direct effects, indirect effects, and feedback cycles in determining stability. Structural sensitivities summarize the degree to which each direct effect contributes to stabilizing feedback or destabilizing feedback or both. Structural sensitivities prove useful in identifying ecologically important feedback cycles within the community structure and for detecting direct effects that have strong, or weak, influences on community stability. The approach may guide the development of management intervention and research design. We demonstrate its value with two theoretical models and two empirical examples of different levels of complexity. ?? 2009 Elsevier B.V. All rights reserved.

Stabilization challenges and formulation strategies associated with oral biologic drug delivery systems.

Science.gov (United States)

Truong-Le, Vu; Lovalenti, Phillip M; Abdul-Fattah, Ahmad M

2015-10-01

Delivery of proteins to mucosal tissues of GI tract typically utilize formulations which protect against proteolysis and target the mucosal tissues. Using case studies from literature and the authors' own work, the in-process stability and solid state storage stability of biopharmaceuticals formulated in delivery systems designed for oral delivery to the GI tract will be reviewed. Among the range of delivery systems, biodegradable polymer systems for protection and controlled release of proteins have been the most studied; hence these systems will be covered in greater depth. These delivery systems include polymeric biodegradable microspheres or nanospheres that contain proteins or vaccines, which are designed to reduce the number of administrations/inoculations and the total protein dose required to achieve the desired biological effect. Specifically, this review will include a landscape survey of the systems that have been studied, the manufacturing processes involved, stability through the manufacturing process, key pharmaceutical formulation parameters that impact stability of the encased proteins, and storage stability of the encapsulated proteins in these delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

On stabilization of linear systems with stochastic disturbances and input saturation

NARCIS (Netherlands)

Stoorvogel, A.A.; Weiland, S.; Saberi, A.

2004-01-01

It is well-known that for linear systems internal asymptotic stability implies external stability in the sense that when the external input is in Lp then also the state will be in Lp. However, for the control of linear systems with saturation where the controlled system is nonlinear this implication

Computation of robustly stabilizing PID controllers for interval systems.

Science.gov (United States)

Matušů, Radek; Prokop, Roman

2016-01-01

The paper is focused on the computation of all possible robustly stabilizing Proportional-Integral-Derivative (PID) controllers for plants with interval uncertainty. The main idea of the proposed method is based on Tan's (et al.) technique for calculation of (nominally) stabilizing PI and PID controllers or robustly stabilizing PI controllers by means of plotting the stability boundary locus in either P-I plane or P-I-D space. Refinement of the existing method by consideration of 16 segment plants instead of 16 Kharitonov plants provides an elegant and efficient tool for finding all robustly stabilizing PID controllers for an interval system. The validity and relatively effortless application of presented theoretical concepts are demonstrated through a computation and simulation example in which the uncertain mathematical model of an experimental oblique wing aircraft is robustly stabilized.

Performance of Power System Stabilizer (UNITROL D) in Benghazi North Power Plant

OpenAIRE

T. Hussein

2011-01-01

The use of power system stabilizers (PSSs) to damp power system swing mode of oscillations is practical important. Our purpose is to retune the power system stabilizer (PSS1A) parameters in Unitrol D produced by ABB– was installed in 1995in Benghazi North Power Plants (BNPPs) at General Electricity Company of Libya (GECOL). The optimal values of the power system stabilizer (PSS1A) parameters are determined off-line by a particle swarm optimization technique (PSO). The obj...

System Design Description PFP Thermal Stabilization

International Nuclear Information System (INIS)

RISENMAY, H.R.

2000-01-01

The purpose of this document is to provide a system design description (SDD) and design basis for the Plutonium Finishing Plant (PFP) Thermal Stabilization project. The chief objective of the SDD is to document the Structures, Systems, and Components (SSCs) that establish and maintain the facility Safety Envelope necessary for normal safe operation of the facility; as identified in the FSAR, the OSRs, and Safety Assessment Documents (SADs). This safety equipment documentation should satisfy guidelines for the SDD given in WHC-SD-CP-TI-18 1, Criteria for Identification and Control of Equipment Necessary for Preservation of the Safety Envelope and Safe Operation of PFP. The basis for operational, alarm response, maintenance, and surveillance procedures are also identified and justified in this document. This document and its appendices address the following elements of the PFP Thermal Stabilization project: Functional and design requirements; Design description; Safety Envelope Analysis; Safety Equipment Class; and Operational, maintenance and surveillance procedures

The electric power engineering handbook power system stability and control

CERN Document Server

Grisby, Leonard L

2012-01-01

With contributions from worldwide leaders in the field, Power System Stability and Control, Third Edition (part of the five-volume set, The Electric Power Engineering Handbook) updates coverage of recent developments and rapid technological growth in essential aspects of power systems. Edited by L.L. Grigsby, a respected and accomplished authority in power engineering, and section editors Miroslav Begovic, Prabha Kundur, and Bruce Wollenberg, this reference presents substantially new and revised content. Topics covered include: * Power System Protection * Power System Dynamics and Stability *

Stabilization and regulation of nonlinear systems a robust and adaptive approach

CERN Document Server

Chen, Zhiyong

2015-01-01

The core of this textbook is a systematic and self-contained treatment of the nonlinear stabilization and output regulation problems. Its coverage embraces both fundamental concepts and advanced research outcomes and includes many numerical and practical examples. Several classes of important uncertain nonlinear systems are discussed. The state-of-the art solution presented uses robust and adaptive control design ideas in an integrated approach which demonstrates connections between global stabilization and global output regulation allowing both to be treated as stabilization problems. Stabilization and Regulation of Nonlinear Systems takes advantage of rich new results to give students up-to-date instruction in the central design problems of nonlinear control, problems which are a driving force behind the furtherance of modern control theory and its application. The diversity of systems in which stabilization and output regulation become significant concerns in the mathematical formulation of practical contr...

Stability in dynamical systems I

International Nuclear Information System (INIS)

Courant, E.D.; Ruth, R.D.; Weng, W.T.

1984-08-01

We have reviewed some of the basic techniques which can be used to analyze stability in nonlinear dynamical systems, particularly in circular particle accelerators. We have concentrated on one-dimensional systems in the examples in order to simply illustrate the general techniques. We began with a review of Hamiltonian dynamics and canonical transformations. We then reviewed linear equations with periodic coefficients using the basic techniques from accelerator theory. To handle nonlinear terms we developed a canonical perturbation theory. From this we calculated invariants and the amplitude dependence of the frequency. This led us to resonances. We studied the cubic resonance in detail by using a rotating coordinate system in phase space. We then considered a general isolated nonlinear resonance. In this case we calculated the width of the resonance and estimated the spacing of resonances in order to use the Chirikov criterion to restrict the validity of the analysis. Finally the resonance equation was reduced to the pendulum equation, and we examined the motion on a separatrix. This brought us to the beginnings of stochastic behavior in the neighborhood of the separatrix. It is this complex behavior in the neighborhood of the separatrix which causes the perturbation theory used here to diverge in many cases. In spite of this the methods developed here have been and are used quite successfully to study nonlinear effects in nearly integrable systems. When used with caution and in conjunction with numerical work they give tremendous insight into the nature of the phase space structure and the stability of nonlinear differential equations. 14 references

Stability and Bifurcation Analysis in a Maglev System with Multiple Delays

Science.gov (United States)

Zhang, Lingling; Huang, Jianhua; Huang, Lihong; Zhang, Zhizhou

This paper considers the time-delayed feedback control for Maglev system with two discrete time delays. We determine constraints on the feedback time delays which ensure the stability of the Maglev system. An algorithm is developed for drawing a two-parametric bifurcation diagram with respect to two delays τ1 and τ2. Direction and stability of periodic solutions are also determined using the normal form method and center manifold theory by Hassard. The complex dynamical behavior of the Maglev system near the domain of stability is confirmed by exhaustive numerical simulation.

Dynamic Voltage Stability Studies using a Modified IEEE 30-Bus System

Directory of Open Access Journals (Sweden)

Oluwafemi Emmanuel Oni

2016-09-01

Full Text Available Power System stability is an essential study in the planning and operation of an efficient, economic, reliable and secure electric power system because it encompasses all the facet of power systems operations, from planning, to conceptual design stages of the project as well as during the systems operating life span. This paper presents different scenario of power system stability studies on a modified IEEE 30-bus system which is subjected to different faults conditions. A scenario whereby the longest high voltage alternating current (HVAC line is replaced with a high voltage direct current (HVDC line was implemented. The results obtained show that the HVDC line enhances system stability more compared to the contemporary HVAC line. Dynamic analysis using RMS simulation tool was used on DigSILENT PowerFactory.

Design of rapid prototype of UAV line-of-sight stabilized control system

Science.gov (United States)

Huang, Gang; Zhao, Liting; Li, Yinlong; Yu, Fei; Lin, Zhe

2018-01-01

The line-of-sight (LOS) stable platform is the most important technology of UAV (unmanned aerial vehicle), which can reduce the effect to imaging quality from vibration and maneuvering of the aircraft. According to the requirement of LOS stability system (inertial and optical-mechanical combined method) and UAV's structure, a rapid prototype is designed using based on industrial computer using Peripheral Component Interconnect (PCI) and Windows RTX to exchange information. The paper shows the control structure, and circuit system including the inertial stability control circuit with gyro and voice coil motor driven circuit, the optical-mechanical stability control circuit with fast-steering-mirror (FSM) driven circuit and image-deviation-obtained system, outer frame rotary follower, and information-exchange system on PC. Test results show the stability accuracy reaches 5μrad, and prove the effectiveness of the combined line-of-sight stabilization control system, and the real-time rapid prototype runs stable.

Effect Mechanism of Penstock on Stability and Regulation Quality of Turbine Regulating System

Directory of Open Access Journals (Sweden)

Wencheng Guo

2014-01-01

Full Text Available This paper studies the effect mechanism of water inertia and head loss of penstock on stability and regulation quality of turbine regulating system with surge tank or not and proposes the construction method of equivalent model of regulating system. Firstly, the complete linear mathematical model of regulating system is established. Then, the free oscillation equation and time response of the frequency that describe stability and regulation quality, respectively, are obtained. Finally, the effects of penstock are analysed by using stability region and response curves. The results indicate that the stability and regulation quality of system without surge tank are determined by time response of frequency which only depends on water hammer wave in penstock, while, for system with surge tank, the time response of frequency depending on water hammer wave in penstock and water-level fluctuation in surge tank jointly determines the stability and regulation quality. Water inertia of penstock mainly affects the stability and time response of frequency of system without surge tank as well as the stability and head wave of time response of frequency with surge tank. Head loss of penstock mainly affects the stability and tail wave of time response of frequency with surge tank.

14 CFR 25.672 - Stability augmentation and automatic and power-operated systems.

Science.gov (United States)

2010-01-01

... power-operated systems. 25.672 Section 25.672 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Construction Control Systems § 25.672 Stability augmentation and automatic and power-operated systems. If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show...

Finite-Time Stability and Controller Design of Continuous-Time Polynomial Fuzzy Systems

Directory of Open Access Journals (Sweden)

Xiaoxing Chen

2017-01-01

Full Text Available Finite-time stability and stabilization problem is first investigated for continuous-time polynomial fuzzy systems. The concept of finite-time stability and stabilization is given for polynomial fuzzy systems based on the idea of classical references. A sum-of-squares- (SOS- based approach is used to obtain the finite-time stability and stabilization conditions, which include some classical results as special cases. The proposed conditions can be solved with the help of powerful Matlab toolbox SOSTOOLS and a semidefinite-program (SDP solver. Finally, two numerical examples and one practical example are employed to illustrate the validity and effectiveness of the provided conditions.

On the stability of boundary layers in gas mantle systems

International Nuclear Information System (INIS)

Ohlsson, D.

1978-10-01

In this thesis a systematic investigation of the stability properties of the partially ionized boundary regions of gas mantle systems for a large class of dissipative magneto-hydrodynamic modes is presented. In the partially ionized boundary regions of gas mantle systems several strong stabilizing mechanisms arise due to coupling between various dissipative effects in certain parameter regions. The presence of neutral gas strongly enhances the stabilizing effects in a dual fashion. First in an indirect way by cooling the edge region and second in a direct way by enhancing viscous and heat conduction effects. It has, however, to be pointed out that exceptions from this general picture may be found. The stabilizing influence of neutral gas on a large class of electrostatic as well as electromagnetic modes in the boundary regions of gas blanket systems is contrary to what has been found in low density weakly ionized plasmas. In these latter cases presence of neutral gas has even been found to be responsible for the onset of entirely new classes of instabilities. Thus there is no universal stabilizing or destabilizing effect associated with plasma-neutral gas interaction effects. (author)

Analysis and improvement of digital control stability for master-slave manipulator system

International Nuclear Information System (INIS)

Yoshida, Koichi; Yabuta, Tetsuro

1992-01-01

Some bilateral controls of master-slave system have been designed, which can realize high-fidelity telemanipulation as if the operator were manipulating the object directly. While usual robot systems are controlled by software-servo system using digital computer, little work has been published on design and analysis for digital control of these systems, which must consider time-delay of sensor signals and zero order hold effect of command signals on actuators. This paper presents a digital control analysis for single degree of freedom master-slave system including impedance models of both the human operator and the task object, which clarifies some index for the stability. The stability result shows a virtual master-slave system concepts, which improve the digital control stability. We first analyze a dynamic control method of master-slave system in discrete-time system for the stability problem, which can realize high-fidelity telemanipulation in the continuous-time. Secondly, using the results of the stability analysis, the robust control scheme for master-slave system is proposed, and the validity of this scheme is finally confirmed by the simulation. Consequently, it would be considered that any combination of master and slave modules with dynamic model of these manipulators is possible to construct the stable master-slave system. (author)

Decentralized linear quadratic power system stabilizers for multi ...

Indian Academy of Sciences (India)

Introduction. Modern excitation systems considerably enhance the overall transient stability of power systems ..... to the local bus rather than the angle δ measured with respect to the remote bus. ... With this in view, the linear and nonlinear per-.

Estudios transculturales del burnout: Los estudios transculturales Brasil-España

Directory of Open Access Journals (Sweden)

Bernardo Moreno Jiménez

2003-01-01

Full Text Available Los estudios transculturales no son un ejercicio secundario y complementario en el estudio de la psicología; un modelo antropológico de la conducta humana obliga a plantear que las variables culturales no son secundarias sino primarias. Por estas razones el estudio del “burnout” o desgaste profesional puede profundizarse mediante la utilización de los métodos transculturales. No es suficiente con la simple comparación de resultados, sino que es necesario buscar instrumentos propios de cada cultura y establecer la comparación no sólo del síndrome de desgaste profesional sino de todos los diferentes elementos del proceso. El trabajo presentado establece las bases teóricas de este planteamiento, y expone, mediante un ejemplo, algunas de las vías posibles para una psicología transcultural del burnout

Self-organizing dynamic stability of far-from-equilibrium biological systems

Science.gov (United States)

Ivanitskii, G. R.

2017-10-01

One indication of the stability of a living system is the variation of the system’s characteristic time scales. Underlying the stability mechanism are the structural hierarchy and self-organization of systems, factors that give rise to a positive (accelerating) feedback and a negative (braking) feedback. Information processing in the brain cortex plays a special role in highly organized living organisms.

Stabilization and synchronization of Genesio-Tesi system via single variable feedback controller

International Nuclear Information System (INIS)

Wang Guangming

2010-01-01

This Letter investigates the stabilization and synchronization of Genesio-Tesi systems. Firstly, modifying the previous method, we stabilize the Genesio-Tesi system. Then, we synchronize two identical Genesio chaotic system by extending the obtained stabilization results. To the best of our knowledge, the above controllers obtained in this Letter are simpler than those obtained in the existing results. Finally, numerical simulations verify the effectiveness and the validity of the above theoretical results.

ON THE STABILIZATION OF THE LINEAR HYBRID SYSTEM STRUCTURE

Directory of Open Access Journals (Sweden)

Kirillov

2014-11-01

Full Text Available The linear control hybrid system, consisting of a fi- nite set of subsystems (modes having different dimensions, is considered. The moments of reset time are determined by some complementary function – evolutionary time. This function satisfies the special complementary ordinary differential equation. The mode stabilization problem is solved for some class of piecewise linear controls. The method of stabilization relies on the set of invariant planes, the existence of which is due to the special form of the hybrid system.

Evaluating the Financial Stability of Banking System, Considering the Emergence Property

Directory of Open Access Journals (Sweden)

Lesik Vitaliy O.

2017-03-01

Full Text Available The article is concerned with analyzing the existing approaches to evaluation of the financial stability of banking system, substantiating the expedience of accounting, and generalizing the characteristics of the emergence property to determine its level. The article considers the interrelation of concepts of «financial stability» and «financial sustainability», the necessity of their correlation, taking account of the time factor, has been substantiated. A critical analysis of the approaches to evaluating the financial stability of banking system has been carried out, their eligibility according to the criteria of accounting of the identification attributes of systemacity and the analytical data aggregation has been examined. To determine the status of banking system as a system phenomenon, the necessity of carrying out an evaluation of its financial stability on the basis of the emergence approach has been substantiated, including the following directions: intensity of credit and financial interaction in the interbank market; functional load of the banking system as to ensuring the macroeconomic development; structural changes and financial disparities in the banking system; scale effects that arise as a consequence of change in the main financial parameters of the system banks.

Frequency Stability Improvement of Low Inertia Systems Using Synchronous Condensers

DEFF Research Database (Denmark)

Nguyen, Ha Thi; Yang, Guangya; Nielsen, Arne Hejde

2016-01-01

of converter interfaced components (wind turbine, HVDC, and Photovoltaic) may have negative effects on the stability of the power system. These components do not have enough inertia response to control frequency excursion, so the power grid can depend on few synchronous machines for frequency regulation...... and reduce the system inertia. Consequently, the frequency stability of the system will be easily jeopardized. To address these issues, the paper studies frequency characteristics of future Western Danish renewable-based system that uses a majority of wind turbine generators. Different scenarios of wind...

Stability properties of nonlinear dynamical systems and evolutionary stable states

Energy Technology Data Exchange (ETDEWEB)

Gleria, Iram, E-mail: iram@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-AL (Brazil); Brenig, Leon [Faculté des Sciences, Université Libre de Bruxelles, 1050 Brussels (Belgium); Rocha Filho, Tarcísio M.; Figueiredo, Annibal [Instituto de Física and International Center for Condensed Matter Physics, Universidade de Brasília, 70919-970 Brasília-DF (Brazil)

2017-03-18

Highlights: • We address the problem of equilibrium stability in a general class of non-linear systems. • We link Evolutionary Stable States (ESS) to stable fixed points of square quasi-polynomial (QP) systems. • We show that an interior ES point may be related to stable interior fixed points of QP systems. - Abstract: In this paper we address the problem of stability in a general class of non-linear systems. We establish a link between the concepts of asymptotic stable interior fixed points of square Quasi-Polynomial systems and evolutionary stable states, a property of some payoff matrices arising from evolutionary games.

LMI optimization approach to stabilization of time-delay chaotic systems

International Nuclear Information System (INIS)

Park, Ju H.; Kwon, O.M.

2005-01-01

Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, this paper proposes a novel control method for stabilization of a class of time-delay chaotic systems. A stabilization criterion is derived in terms of LMIs which can be easily solved by efficient convex optimization algorithms. A numerical example is included to show the advantage of the result derived

Stability of detecting system using NaI(Tl)

International Nuclear Information System (INIS)

Zhuo Yunshang; Lei Zhangyun; Zen Yu; Gong Hua

1996-01-01

A detecting system using NaI(Tl) is widely used in research and industry of nuclear science and other fields. For providing the high accuracy and working well under inclement environment, the stability of detecting system using NaI(Tl) is very important. The variation of environment temperature, the change of counting rate and long time continuous working of detector will cause un-negligible effect on the measurement. Three approaches were used. They are: 1) temperature control (It makes the effect of the variation of environment temperature on the measurement negligible.); 2) spectrum stabilizing (It adjust the peak position of the spectrum when the counting rate changes.); and 3) auto-checking and adjusting (It adjusts the drift of the NaI(Tl) detecting system when it works continuously)

Byzantine-fault tolerant self-stabilizing protocol for distributed clock synchronization systems

Science.gov (United States)

Malekpour, Mahyar R. (Inventor)

2010-01-01

A rapid Byzantine self-stabilizing clock synchronization protocol that self-stabilizes from any state, tolerates bursts of transient failures, and deterministically converges within a linear convergence time with respect to the self-stabilization period. Upon self-stabilization, all good clocks proceed synchronously. The Byzantine self-stabilizing clock synchronization protocol does not rely on any assumptions about the initial state of the clocks. Furthermore, there is neither a central clock nor an externally generated pulse system. The protocol converges deterministically, is scalable, and self-stabilizes in a short amount of time. The convergence time is linear with respect to the self-stabilization period.

Transient Stability Assessment of Power System with Large Amount of Wind Power Penetration

DEFF Research Database (Denmark)

Liu, Leo; Chen, Zhe; Bak, Claus Leth

2012-01-01

Recently, the security and stability of power system with large amount of wind power are the concerned issues, especially the transient stability. In Denmark, the onshore and offshore wind farms are connected to distribution system and transmission system respectively. The control and protection...... methodologies of onshore and offshore wind farms definitely affect the transient stability of power system. In this paper, the onshore and offshore wind farms are modeled in detail in order to assess the transient stability of western Danish power system. Further, the computation of critical clearing time (CCT...... plants, load consumption level and high voltage direct current (HVDC) transmission links are taken into account. The results presented in this paper are able to provide an early awareness of power system security condition of the western Danish power system....

Stability Analysis for Fractional-Order Linear Singular Delay Differential Systems

Directory of Open Access Journals (Sweden)

Hai Zhang

2014-01-01

Full Text Available We investigate the delay-independently asymptotic stability of fractional-order linear singular delay differential systems. Based on the algebraic approach, the sufficient conditions are presented to ensure the asymptotic stability for any delay parameter. By applying the stability criteria, one can avoid solving the roots of transcendental equations. An example is also provided to illustrate the effectiveness and applicability of the theoretical results.

Analysis of the gyroscopic stabilization of a system of rigid bodies

DEFF Research Database (Denmark)

Kliem, Wolfhard; Seyranian, Alexander P.

1997-01-01

We study the gyroscopic stability of a three-body system. A new method of finding stability regions, based on mechanism and criteria for gyroscopic stabilization, is presented. Of particular interest in this connection is the theory of interaction of eigenvalues. This leads to a complete 3......-dimensional analysis, which shows the regions of stability, divergence, and flutter of a simple model of a rotating spaceship....

Combined analytical and numerical approaches in Dynamic Stability analyses of engineering systems

Science.gov (United States)

Náprstek, Jiří

2015-03-01

Dynamic Stability is a widely studied area that has attracted many researchers from various disciplines. Although Dynamic Stability is usually associated with mechanics, theoretical physics or other natural and technical disciplines, it is also relevant to social, economic, and philosophical areas of our lives. Therefore, it is useful to occasionally highlight the general aspects of this amazing area, to present some relevant examples and to evaluate its position among the various branches of Rational Mechanics. From this perspective, the aim of this study is to present a brief review concerning the Dynamic Stability problem, its basic definitions and principles, important phenomena, research motivations and applications in engineering. The relationships with relevant systems that are prone to stability loss (encountered in other areas such as physics, other natural sciences and engineering) are also noted. The theoretical background, which is applicable to many disciplines, is presented. In this paper, the most frequently used Dynamic Stability analysis methods are presented in relation to individual dynamic systems that are widely discussed in various engineering branches. In particular, the Lyapunov function and exponent procedures, Routh-Hurwitz, Liénard, and other theorems are outlined together with demonstrations. The possibilities for analytical and numerical procedures are mentioned together with possible feedback from experimental research and testing. The strengths and shortcomings of these approaches are evaluated together with examples of their effective complementing of each other. The systems that are widely encountered in engineering are presented in the form of mathematical models. The analyses of their Dynamic Stability and post-critical behaviour are also presented. The stability limits, bifurcation points, quasi-periodic response processes and chaotic regimes are discussed. The limit cycle existence and stability are examined together with their

Optimal Parameter Selection of Power System Stabilizer using Genetic Algorithm

Energy Technology Data Exchange (ETDEWEB)

Chung, Hyeng Hwan; Chung, Dong Il; Chung, Mun Kyu [Dong-AUniversity (Korea); Wang, Yong Peel [Canterbury Univeristy (New Zealand)

1999-06-01

In this paper, it is suggested that the selection method of optimal parameter of power system stabilizer (PSS) with robustness in low frequency oscillation for power system using real variable elitism genetic algorithm (RVEGA). The optimal parameters were selected in the case of power system stabilizer with one lead compensator, and two lead compensator. Also, the frequency responses characteristics of PSS, the system eigenvalues criterion and the dynamic characteristics were considered in the normal load and the heavy load, which proved usefulness of RVEGA compare with Yu's compensator design theory. (author). 20 refs., 15 figs., 8 tabs.

Advances in power system modelling, control and stability analysis

CERN Document Server

Milano, Federico

2016-01-01

Advances in Power System Modelling, Control and Stability Analysis captures the variety of new methodologies and technologies that are changing the way modern electric power systems are modelled, simulated and operated.

Stability analysis of switched linear systems defined by graphs

NARCIS (Netherlands)

Athanasopoulos, N.; Lazar, M.

2014-01-01

We present necessary and sufficient conditions for global exponential stability for switched discrete-time linear systems, under arbitrary switching, which is constrained within a set of admissible transitions. The class of systems studied includes the family of systems under arbitrary switching,

Stabilization of discrete-time LTI positive systems

Directory of Open Access Journals (Sweden)

Krokavec Dušan

2017-12-01

Full Text Available The paper mitigates the existing conditions reported in the previous literature for control design of discrete-time linear positive systems. Incorporating an associated structure of linear matrix inequalities, combined with the Lyapunov inequality guaranteing asymptotic stability of discrete-time positive system structures, new conditions are presented with which the state-feedback controllers and the system state observers can be designed. Associated solutions of the proposed design conditions are illustrated by numerical illustrative examples.

New Results of Global Exponential Stabilization for BLDCMs System

OpenAIRE

Fengxia Tian; Fangchao Zhen; Guopeng Zhou; Xiaoxin Liao

2015-01-01

The global exponential stabilization for brushless direct current motor (BLDCM) system is studied. Four linear and simple feedback controllers are proposed to realize the global stabilization of BLDCM with exponential convergence rate; the control law used in each theorem is less conservative and more concise. Finally, an example is given to demonstrate the correctness of the proposed results.

Evaluation of Laser Stabilization and Imaging Systems for LCLS-II - Final Paper

Energy Technology Data Exchange (ETDEWEB)

Barry, Matthew [Auburn Univ., AL (United States)

2015-08-20

By combining the top performing commercial laser beam stabilization system with the most ideal optical imaging configuration, the beamline for the Linear Accelerator Coherent Light Source II (LCLS-II) will deliver the highest quality and most stable beam to the cathode. To determine the optimal combination, LCLS-II beamline conditions were replicated and the systems tested with a He-Ne laser. The Guidestar-II and MRC active laser beam stabilization systems were evaluated for their ideal positioning and stability. Both a two and four lens optical imaging configuration was then evaluated for beam imaging quality, magnification properties, and natural stability. In their best performances when tested over fifteen hours, Guidestar-II kept the beam stable over approximately 70-110um while the MRC system kept it stable over approximately 90-100um. During short periods of time, Guidestar-II kept the beam stable between 10-20um, but was more susceptible to drift over time, while the MRC system maintained the beam between 30-50um with less overall drift. The best optical imaging configuration proved to be a four lens system that images to the iris located in the cathode room and from there, imaged to the cathode. The magnification from the iris to the cathode was 2:1, within an acceptable tolerance to the expected 2.1:1 magnification. The two lens configuration was slightly more stable in small periods of time (less than 10 minutes) without the assistance of a stability system, approximately 55um compared to approximately 70um, but the four lens configurations beam image had a significantly flatter intensity distribution compared to the two lens configuration which had a Gaussian distribution. A final test still needs to be run with both stability systems running at the same time through the four lens system. With this data, the optimal laser beam stabilization system can be determined for the beamline of LCLS-II.

A Study of Strong Stability of Distributed Systems. Ph.D. Thesis

Science.gov (United States)

Cataltepe, Tayfun

1989-01-01

The strong stability of distributed systems is studied and the problem of characterizing strongly stable semigroups of operators associated with distributed systems is addressed. Main emphasis is on contractive systems. Three different approaches to characterization of strongly stable contractive semigroups are developed. The first one is an operator theoretical approach. Using the theory of dilations, it is shown that every strongly stable contractive semigroup is related to the left shift semigroup on an L(exp 2) space. Then, a decomposition for the state space which identifies strongly stable and unstable states is introduced. Based on this decomposition, conditions for a contractive semigroup to be strongly stable are obtained. Finally, extensions of Lyapunov's equation for distributed parameter systems are investigated. Sufficient conditions for weak and strong stabilities of uniformly bounded semigroups are obtained by relaxing the equivalent norm condition on the right hand side of the Lyanupov equation. These characterizations are then applied to the problem of feedback stabilization. First, it is shown via the state space decomposition that under certain conditions a contractive system (A,B) can be strongly stabilized by the feedback -B(*). Then, application of the extensions of the Lyapunov equation results in sufficient conditions for weak, strong, and exponential stabilizations of contractive systems by the feedback -B(*). Finally, it is shown that for a contractive system, the first derivative of x with respect to time = Ax + Bu (where B is any linear bounded operator), there is a related linear quadratic regulator problem and a corresponding steady state Riccati equation which always has a bounded nonnegative solution.

The armenian power system operation stability investigation accounting putting new power systems into operation

International Nuclear Information System (INIS)

Yeghiazaryan, L.V.; Hakobyan, S.G.; Gharibyan, G.V.; Harutyunyan, G.S.; Galstyan, G.H.

2010-01-01

The description of the power systems operation stability failure caused by the system significant emergency states occurred during the last working period in Armenian and USA power systems is performed. With the use of PSSTME-31 software portfolio of Siemens Firm a design model is developed and transient electromechanical process calculations for Armenian power system are performed. The accuracy of the model is checked by comparing real-time transient state parameters and their reproduction calculation results.The Armenia - Iran current power transmission lines permissible limit under the condition of the static and dynamic stability requirements and in case of the new thermal power units maintenance are defined

Experimental study of flame stability in biogas premix system

International Nuclear Information System (INIS)

Diaz G, Carlos A; Amell A Andres; Cardona Luis F

2008-01-01

Utilization of new renewable energy sources have had a special interest in last years looking for decrease the dependence of fossil fuels and the environmental impact generated for them. This work studies experimentally the flame stability of a simulated biogas with a volumetric composition of 60% methane and 40% carbon dioxide. The objective of this study is to obtain information about design and interchangeability of gases in premixed combustion systems that operate with different fuel gases. The critical velocity gradient was the stability criteria used. Utilization of this criteria and the experimental method followed, using a partial premixed burner, stability flame diagram of biogas studied had been obtained. Presence of carbon dioxide has a negative effect in flame stability, decreasing significantly the laminar flame speed and consequently, the stability range of biogas burners because of apparition of blow off.

Mobile Phenotyping System Using an Aeromotively Stabilized Cable-Driven Robot

Science.gov (United States)

Newman, M. B.; Zygielbaum, A. I.

2017-12-01

Agricultural researchers are constantly attempting to generate superior agricultural crops. Whether this means creating crops with greater yield, crops that are more resilient to disease, or crops that can tolerate harsh environments with fewer failures, test plots of these experimental crops must be studied in real-world environments with minimal invasion to determine how they will perform in full-scale agricultural settings. To monitor these crops without interfering with their natural growth, a noninvasive sensor system has been implemented. This system, instituted by the College of Agricultural Sciences and Natural Resources at the University of Nebraska - Lincoln (UNL), uses a system of poles, cables, and winches to support and maneuver a sensor platform above the crops at an outdoor phenotyping site. In this work, we improve upon the UNL outdoor phenotyping system presenting the concept design for a mobile, cable-driven phenotyping system as opposed to a permanent phenotyping facility. One major challenge in large-scale, cable-driven robots is stability of the end-effector. As a result, this mobile system seeks to use a novel method of end-effector stabilization using an onboard rotor drive system, herein referred to as the Instrument Platform Aeromotive Stabilization System (IPASS). A prototype system is developed and analyzed to determine the viability of IPASS.

Midterm Stability Evaluation of Wide-area Power System by using Synchronized Phasor Measurements

Science.gov (United States)

Ota, Yutaka; Ukai, Hiroyuki; Nakamura, Koichi; Fujita, Hideki

In recent years, the PMU (Phasor Measurement Unit) receives a great deal of attention as a synchronized measurement system of power systems. Synchronized phasor angles obtained by the PMU provide the effective information for evaluating the stability of a bulk power system. The aspect of instability phenomena during midterm tends to be more complicated, and the stability analysis using the synchronized phasor measurements is significant in order to keep a complicated power system stable. This paper proposes a midterm stability evaluation method of the wide-area power system by using the synchronized phasor measurements. By clustering and aggregating the power system to some coherent groups, the step-out is effectively predicted on the basis of the two-machine equivalent power system model. The midterm stability of a longitudinal power system model of Japanese 60Hz systems constructed by the PSA, which is a hybrid-type power system simulator, is practically evaluated using the proposed method.

Fixed-Time Stability of the Hydraulic Turbine Governing System

Directory of Open Access Journals (Sweden)

Caoyuan Ma

2018-01-01

Full Text Available This paper studies the problem of fixed-time stability of hydraulic turbine governing system with the elastic water hammer nonlinear model. To control and improve the quality of hydraulic turbine governing system, a new fixed-time control strategy is proposed, which can stabilize the water turbine governing system within a fixed time. Compared with the finite-time control strategy where the convergence rate depends on the initial state, the settling time of the fixed-time control scheme can be adjusted to the required value regardless of the initial conditions. Finally, we numerically show that the fixed-time control is more effective than and superior to the finite-time control.

Stochastic stability of four-wheel-steering system

International Nuclear Information System (INIS)

Huang Dongwei; Wang Hongli; Zhu Zhiwen; Feng Zhang

2007-01-01

A four-wheel-steering system subjected to white noise excitations was reduced to a two-degree-of-freedom quasi-non-integrable-Hamiltonian system. Subsequently we obtained an one-dimensional Ito stochastic differential equation for the averaged Hamiltonian of the system by using the stochastic averaging method for quasi-non-integrable-Hamiltonian systems. Thus, the stochastic stability of four-wheel-steering system was analyzed by analyzing the sample behaviors of the averaged Hamiltonian at the boundary H = 0 and calculating its Lyapunov exponent. An example given at the end demonstrated that the conclusion obtained is of considerable significance

An equilibrium point stabilization strategy for the Chen system

International Nuclear Information System (INIS)

Alvarez-Ramirez, Jose; Cevantes, Ilse; Femat, Ricardo

2004-01-01

The aim of this Letter is to address the equilibrium point stabilization problem of the Chen system by employing a simple linear feedback controller derived from time-scaling the dynamics of a single variable. The controller has the advantage of being easy to implement and a rigorous stability proof is provided based on singular perturbation arguments. Results are illustrated via numerical simulations

Stabilizing periodic orbits of chaotic systems using fuzzy adaptive sliding mode control

Energy Technology Data Exchange (ETDEWEB)

Layeghi, Hamed [Department of Mechanical Engineering, Sharif University of Technology, Center of Excellence in Design, Robotics and Automation, Azadi Avenue, Postal Code 11365-9567 Tehran (Iran, Islamic Republic of)], E-mail: layeghi@mech.sharif.edu; Arjmand, Mehdi Tabe [Department of Mechanical Engineering, Sharif University of Technology, Center of Excellence in Design, Robotics and Automation, Azadi Avenue, Postal Code 11365-9567 Tehran (Iran, Islamic Republic of)], E-mail: arjmand@mech.sharif.edu; Salarieh, Hassan [Department of Mechanical Engineering, Sharif University of Technology, Center of Excellence in Design, Robotics and Automation, Azadi Avenue, Postal Code 11365-9567 Tehran (Iran, Islamic Republic of)], E-mail: salarieh@mech.sharif.edu; Alasty, Aria [Department of Mechanical Engineering, Sharif University of Technology, Center of Excellence in Design, Robotics and Automation, Azadi Avenue, Postal Code 11365-9567 Tehran (Iran, Islamic Republic of)], E-mail: aalasti@sharif.edu

2008-08-15

In this paper by using a combination of fuzzy identification and the sliding mode control a fuzzy adaptive sliding mode scheme is designed to stabilize the unstable periodic orbits of chaotic systems. The chaotic system is assumed to have an affine form x{sup (n)} = f(X) + g(X)u where f and g are unknown functions. Using only the input-output data obtained from the underlying dynamical system, two fuzzy systems are constructed for identification of f and g. Two distinct methods are utilized for fuzzy modeling, the least squares and the gradient descent techniques. Based on the estimated fuzzy models, an adaptive controller, which works through the sliding mode control, is designed to make the system track the desired unstable periodic orbits. The stability analysis of the overall closed loop system is presented in the paper and the effectiveness of the proposed adaptive scheme is numerically investigated. As a case of study, modified Duffing system is selected for applying the proposed method to stabilize its 2{pi} and 4{pi} periodic orbits. Simulation results show the high performance of the method for stabilizing the unstable periodic orbits of unknown chaotic systems.

Stability and stabilisation of a class of networked dynamic systems

Science.gov (United States)

Liu, H. B.; Wang, D. Q.

2018-04-01

We investigate the stability and stabilisation of a linear time invariant networked heterogeneous system with arbitrarily connected subsystems. A new linear matrix inequality based sufficient and necessary condition for the stability is derived, based on which the stabilisation is provided. The obtained conditions efficiently utilise the block-diagonal characteristic of system parameter matrices and the sparseness of subsystem connection matrix. Moreover, a sufficient condition only dependent on each individual subsystem is also presented for the stabilisation of the networked systems with a large scale. Numerical simulations show that these conditions are computationally valid in the analysis and synthesis of a large-scale networked system.

Power system dynamics and stability with synchrophasor measurement and power system toolbox

CERN Document Server

Sauer, Peter W; Chow, Joe H

2017-01-01

This new edition addresses the needs of dynamic modeling and simulation relevant to power system planning, design, and operation, including a systematic derivation of synchronous machine dynamic models together with speed and voltage control subsystems. Reduced-order modeling based on integral manifolds is used as a firm basis for understanding the derivations and limitations of lower-order dynamic models. Following these developments, a multi-machine model interconnected through the transmission network is formulated and simulated using numerical simulation methods. Energy function methods are discussed for direct evaluation of stability. Small-signal analysis is used for determining the electromechanical modes and mode-shapes, and for power system stabilizer design. Time-synchronized high-sampling-rate phasor measurement units (PMUs) to monitor power system disturbances ave been implemented throughout North America and many other countries. In this second edition, new chapters on synchrophasor measurement ...

Stability and Hopf bifurcation analysis of a new system

International Nuclear Information System (INIS)

Huang Kuifei; Yang Qigui

2009-01-01

In this paper, a new chaotic system is introduced. The system contains special cases as the modified Lorenz system and conjugate Chen system. Some subtle characteristics of stability and Hopf bifurcation of the new chaotic system are thoroughly investigated by rigorous mathematical analysis and symbolic computations. Meanwhile, some numerical simulations for justifying the theoretical analysis are also presented.

L2-stability of the Vlasov-Maxwell-Boltzmann system near global Maxwellians

International Nuclear Information System (INIS)

Ha, Seung-Yeal; Xiao, Qinghua; Xiong, Linjie; Zhao, Huijiang

2013-01-01

We present a L 2 -stability theory of the Vlasov-Maxwell-Boltzmann system for the two-species collisional plasma. We show that in a perturbative regime of a global Maxwellian, the L 2 -distance between two strong solutions can be controlled by that between initial data in a Lipschitz manner. Our stability result extends earlier results [Ha, S.-Y. and Xiao, Q.-H., “A revisiting to the L 2 -stability theory of the Boltzmann equation near global Maxwellians,” (submitted) and Ha, S.-Y., Yang, X.-F., and Yun, S.-B., “L 2 stability theory of the Boltzmann equation near a global Maxwellian,” Arch. Ration. Mech. Anal. 197, 657–688 (2010)] on the L 2 -stability of the Boltzmann equation to the Boltzmann equation coupled with self-consistent external forces. As a direct application of our stability result, we show that classical solutions in Duan et al. [“Optimal large-time behavior of the Vlasov-Maxwell-Boltzmann system in the whole space,” Commun. Pure Appl. Math. 24, 1497–1546 (2011)] and Guo [“The Vlasov-Maxwell-Boltzmann system near Maxwellians,” Invent. Math. 153(3), 593–630 (2003)] satisfy a uniform L 2 -stability estimate. This is the first result on the L 2 -stability of the Boltzmann equation coupled with self-consistent field equations in three dimensions

Asymptotic Stabilization of Non-holonomic Port-controlled Hamiltonian Systems

DEFF Research Database (Denmark)

Sørensen, Mathias Jesper; Bendtsen, Jan Dimon; Andersen, Palle

2004-01-01

A novel method for asymptotic stabilization of a class of non-holonomic systems is presented. The method is based on the port-controlled Hamiltonian description of electro-mechanical systems. The general system is augmented with so-called kinematic inputs, thus representing a special class of mob...

A Recursive Fuzzy System for Efficient Digital Image Stabilization

Directory of Open Access Journals (Sweden)

Nikolaos Kyriakoulis

2008-01-01

Full Text Available A novel digital image stabilization technique is proposed in this paper. It is based on a fuzzy Kalman compensation of the global motion vector (GMV, which is estimated in the log-polar plane. The GMV is extracted using four local motion vectors (LMVs computed on respective subimages in the logpolar plane. The fuzzy Kalman system consists of a fuzzy system with the Kalman filter's discrete time-invariant definition. Due to this inherited recursiveness, the output results into smoothed image sequences. The proposed stabilization system aims to compensate any oscillations of the frame absolute positions, based on the motion estimation in the log-polar domain, filtered by the fuzzy Kalman system, and thus the advantages of both the fuzzy Kalman system and the log-polar transformation are exploited. The described technique produces optimal results in terms of the output quality and the level of compensation.

Estimation of the Influence of Power System Mathematical Model Parameter Uncertainty on PSS2A System Stabilizers

Directory of Open Access Journals (Sweden)

Adrian Nocoń

2015-09-01

Full Text Available This paper presents an analysis of the influence of uncertainty of power system mathematical model parameters on optimised parameters of PSS2A system stabilizers. Optimisation of power system stabilizer parameters was based on polyoptimisation (multi-criteria optimisation. Optimisation criteria were determined for disturbances occurring in a multi-machine power system, when taking into account transient waveforms associated with electromechanical swings (instantaneous power, angular speed and terminal voltage waveforms of generators. A genetic algorithm with floating-point encoding, tournament selection, mean crossover and perturbative mutations, modified for the needs of investigations, was used for optimisation. The impact of uncertainties on the quality of operation of power system stabilizers with optimised parameters has been evaluated using various deformation factors.

Validación de métodos analíticos para los estudios de estabilidad del naproxeno en supositorios para uso infantil y adulto Validation of analytical methods for the stability studies of naproxen suppositories for infant and adult use

Directory of Open Access Journals (Sweden)

Yaslenis Rodríguez Hernández

2011-12-01

Full Text Available En el presente trabajo se realizaron los estudios analíticos y de validación para su aplicación en los estudios de estabilidad de las futuras formulaciones de supositorios de naproxeno para uso infantil y adulto. Se determinaron los factores que más influyeron en la estabilidad del naproxeno; la mayor degradación ocurrió en el medio ácido, oxidante y por acción de la luz. Se evaluó un método por cromatografía líquida de alta resolución, el cual mostró adecuado desempeño para cuantificar naproxeno en supositorios y fue selectivo frente a los productos de degradación. Se obtuvo un límite de cuantificación de 3,480 µg, por lo que fue válido para la realización de dichos estudios. Adicionalmente, se evaluaron los parámetros especificidad para estabilidad, límites de detección y de cuantificación para el método por volumetría ácido-base semiacuosa directa validado anteriormente para control de calidad, lo cual mostró resultados satisfactorios. No obstante, los métodos volumétricos no se consideran indicadores de estabilidad, por lo que este método será utilizado conjuntamente con los métodos cromatográficos de elección para determinar productos de degradación: cromatografía de capa delgada y cromatografía líquida de alta resolución.Analytical and validating studies were performed in this paper, with a view to using them in the stability studies of the future formulations of naproxen suppositories for children and adults. The most influential factors in the naproxen stability were determined, that is, the major degradation occurred in acid medium, oxidative medium and by light action. One high-performance liquid chromatography-based method was evaluated, which proved to be adequate to quantify naproxen in suppositories and was selective against degradation products. The quantification limit was 3,480 µg, so it was valid for these studies. Additionally, the parameters specificity for stability, detection and

DESCRIBING FUNCTION METHOD FOR PI-FUZZY CONTROLLED SYSTEMS STABILITY ANALYSIS

Directory of Open Access Journals (Sweden)

Stefan PREITL

2004-12-01

Full Text Available The paper proposes a global stability analysis method dedicated to fuzzy control systems containing Mamdani PI-fuzzy controllers with output integration to control SISO linear / linearized plants. The method is expressed in terms of relatively simple steps, and it is based on: the generalization of the describing function method for the considered fuzzy control systems to the MIMO case, the approximation of the describing functions by applying the least squares method. The method is applied to the stability analysis of a class of PI-fuzzy controlled servo-systems, and validated by considering a case study.

Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

Directory of Open Access Journals (Sweden)

Chen Qin

2013-01-01

Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

Interpreting Popov criteria in Lure´ systems with complex scaling stability analysis

Science.gov (United States)

Zhou, J.

2018-06-01

The paper presents a novel frequency-domain interpretation of Popov criteria for absolute stability in Lure´ systems by means of what we call complex scaling stability analysis. The complex scaling technique is developed for exponential/asymptotic stability in LTI feedback systems, which dispenses open-loop poles distribution, contour/locus orientation and prior frequency sweeping. Exploiting the technique for alternatively revealing positive realness of transfer functions, re-interpreting Popov criteria is explicated. More specifically, the suggested frequency-domain stability conditions are conformable both in scalar and multivariable cases, and can be implemented either graphically with locus plotting or numerically without; in particular, the latter is suitable as a design tool with auxiliary parameter freedom. The interpretation also reveals further frequency-domain facts about Lure´ systems. Numerical examples are included to illustrate the main results.

Stability Analysis of Periodic Systems by Truncated Point Mappings

Science.gov (United States)

Guttalu, R. S.; Flashner, H.

1996-01-01

An approach is presented deriving analytical stability and bifurcation conditions for systems with periodically varying coefficients. The method is based on a point mapping(period to period mapping) representation of the system's dynamics. An algorithm is employed to obtain an analytical expression for the point mapping and its dependence on the system's parameters. The algorithm is devised to derive the coefficients of a multinominal expansion of the point mapping up to an arbitrary order in terms of the state variables and of the parameters. Analytical stability and bifurcation condition are then formulated and expressed as functional relations between the parameters. To demonstrate the application of the method, the parametric stability of Mathieu's equation and of a two-degree of freedom system are investigated. The results obtained by the proposed approach are compared to those obtained by perturbation analysis and by direct integration which we considered to the "exact solution". It is shown that, unlike perturbation analysis, the proposed method provides very accurate solution even for large valuesof the parameters. If an expansion of the point mapping in terms of a small parameter is performed the method is equivalent to perturbation analysis. Moreover, it is demonstrated that the method can be easily applied to multiple-degree-of-freedom systems using the same framework. This feature is an important advantage since most of the existing analysis methods apply mainly to single-degree-of-freedom systems and their extension to higher dimensions is difficult and computationally cumbersome.

ANALYSIS OF PERTURBED MOTION STABILITY OF WHEELER VEHICLES BRAKES CONTROL SYSTEM

Directory of Open Access Journals (Sweden)

V. Verbytskiyi

2011-01-01

Full Text Available The analysis of the perturbed motion stability of the brake automatic control system on the basis of Lyapunov’s second method is carried out. Using transformations of Lurie there has been ob-tained the canonical form of the system of equations of automatic control. It allowed determining the necessary and sufficient conditions of the asymptotic stability of the system irrespective of its initial condition and a definite choice of the admissible characteristic of the regulator.

Stability considerations of packed multi-planet systems

Science.gov (United States)

Gratia, Pierre; Lissauer, Jack

2018-04-01

I will present our first results of the outcomes of five packed, Earth-mass planetary simulations around a Sun-like star, whose initial separations in terms of their semi-major axes is determined by a multiple of their mutual Hill radius, the parameter beta. In our simulations, we will vary beta between 3.5 and and 9, with a special emphasis on the region around 8.5, where stability times are wildly different for small increments of beta. While the zero initial eccentricity case has been investigated before, we expand on it by allowing for initial nonzero eccentricities of one or more planets. Furthermore, we increase the simulated time by up to one order of magnitude reaching billions of orbits. This of course will determine more accurately the fate of systems that take a long time to go unstable. Both of these investigations have not been done before, thus our findings improve our understanding of the stabilities of closely-spaced planetary systems.

Lyapunov-based Stability of Feedback Interconnections of Negative Imaginary Systems

KAUST Repository

Ghallab, Ahmed G.

2017-10-19

Feedback control systems using sensors and actuators such as piezoelectric sensors and actuators, micro-electro-mechanical systems (MEMS) sensors and opto-mechanical sensors, are allowing new advances in designing such high precision technologies. The negative imaginary control systems framework allows for robust control design for such high precision systems in the face of uncertainties due to unmodelled dynamics. The stability of the feedback interconnection of negative imaginary systems has been well established in the literature. However, the proofs of stability feedback interconnection which are used in some previous papers have a shortcoming due to a matrix inevitability issue. In this paper, we provide a new and correct Lyapunov-based proof of one such result and show that the result is still true.

Lyapunov-based Stability of Feedback Interconnections of Negative Imaginary Systems

KAUST Repository

Ghallab, Ahmed G.; Mabrok, Mohamed; Petersen, Ian R.

2017-01-01

Feedback control systems using sensors and actuators such as piezoelectric sensors and actuators, micro-electro-mechanical systems (MEMS) sensors and opto-mechanical sensors, are allowing new advances in designing such high precision technologies. The negative imaginary control systems framework allows for robust control design for such high precision systems in the face of uncertainties due to unmodelled dynamics. The stability of the feedback interconnection of negative imaginary systems has been well established in the literature. However, the proofs of stability feedback interconnection which are used in some previous papers have a shortcoming due to a matrix inevitability issue. In this paper, we provide a new and correct Lyapunov-based proof of one such result and show that the result is still true.

The beauty of simple adaptive control and new developments in nonlinear systems stability analysis

Energy Technology Data Exchange (ETDEWEB)

Barkana, Itzhak, E-mail: ibarkana@gmail.com [BARKANA Consulting, Ramat Hasharon (Israel)

2014-12-10

Although various adaptive control techniques have been around for a long time and in spite of successful proofs of stability and even successful demonstrations of performance, the eventual use of adaptive control methodologies in practical real world systems has met a rather strong resistance from practitioners and has remained limited. Apparently, it is difficult to guarantee or even understand the conditions that can guarantee stable operations of adaptive control systems under realistic operational environments. Besides, it is difficult to measure the robustness of adaptive control system stability and allow it to be compared with the common and widely used measure of phase margin and gain margin that is utilized by present, mainly LTI, controllers. Furthermore, customary stability analysis methods seem to imply that the mere stability of adaptive systems may be adversely affected by any tiny deviation from the pretty idealistic and assumably required stability conditions. This paper first revisits the fundamental qualities of customary direct adaptive control methodologies, in particular the classical Model Reference Adaptive Control, and shows that some of their basic drawbacks have been addressed and eliminated within the so-called Simple Adaptive Control methodology. Moreover, recent developments in the stability analysis methods of nonlinear systems show that prior conditions that were customarily assumed to be needed for stability are only apparent and can be eliminated. As a result, sufficient conditions that guarantee stability are clearly stated and lead to similarly clear proofs of stability. As many real-world applications show, once robust stability of the adaptive systems can be guaranteed, the added value of using Add-On Adaptive Control along with classical Control design techniques is pushing the desired performance beyond any previous limits.

A field experiment on power line stabilization by SMES system

International Nuclear Information System (INIS)

Irie, F.; Takeo, M.; Sato, S.; Katahira, O.; Fukui, F.; Takamatsu, M.

1992-01-01

In this paper field experiments on stabilization of a hydro power plant by a SMES system are reported, where a generator having a rating of 60 kW at 3.3kV is connected to a 6.6kV power distribution line. The SMES system is composed of two 30kVA GTO convertors and a superconducting magnet system with an energy of 30kJ at 100A. Experiments of stabilization for the generator fluctuation caused by a sudden insertion of inductors in the line are successfully performed for some control modes. The value of the SMES system to compensate for a short period voltage dip is also confirmed

Transient Stability Improvement for Combined Heat and Power System Using Load Shedding

Directory of Open Access Journals (Sweden)

Hung-Cheng Chen

2014-01-01

Full Text Available The purpose of the paper is to analyze and improve the transient stability of an industrial combined heat and power (CHP system in a high-tech science park in Taiwan. The CHP system installed two 161 kV/161 kV high-impendence transformers to connect with Taipower System (TPS for both decreasing the short-circuit fault current and increasing the fault critical clearing time. The transient stabilities of three types of operation modes in CHP units, 3G1S, 2G1S, and 1G1S, are analyzed. Under the 3G1S operation mode, the system frequency is immediately restored to 60 Hz after tie line tripping with the TPS. Under the 1G1S and 2G1S operation modes, the system frequencies will continuously decrease and eventually become unstable. A novel transient stability improvement approach using load shedding technique based on the change in frequency is proposed to improve the transient stability.

Investigation of external and internal shock in the stability of Indonesia’s financial system

Directory of Open Access Journals (Sweden)

Maulina Vinus

2017-07-01

Full Text Available The objective of this research is to develop a financial system stability index and analyze the internal and external factors that we expect to affect the stability of the Indonesian financial system. We measured the single model of financial system stability index (FSSI from year 2004M03 to2014M09 in Indonesia, and compiled a single quantitative measure based on aggregate internal factors and external factors to capture and predict the shocks of the financial system stability. Stability parameters were composed of composite indicators on different bases. In addition, we developed a comprehensive index component associated with the relevant market conditions, including banking soundness index, financial vulnerability index, and regional economic climate index. Results stated that US economic growth and economic growth of ASEAN countries positively affected financial stability. In addition, current account, exchange rate, inflation, interest rate were shown to negatively affect financial stability. The results of this study imply that internal factors have a strong influence on the financial stability. Therefore, the central bank should give a fast and correct response to the changes of external and internal financial environment, especially for internal factors through monetary policy.

Differentiable dynamical systems an introduction to structural stability and hyperbolicity

CERN Document Server

Wen, Lan

2016-01-01

This is a graduate text in differentiable dynamical systems. It focuses on structural stability and hyperbolicity, a topic that is central to the field. Starting with the basic concepts of dynamical systems, analyzing the historic systems of the Smale horseshoe, Anosov toral automorphisms, and the solenoid attractor, the book develops the hyperbolic theory first for hyperbolic fixed points and then for general hyperbolic sets. The problems of stable manifolds, structural stability, and shadowing property are investigated, which lead to a highlight of the book, the \\Omega-stability theorem of Smale. While the content is rather standard, a key objective of the book is to present a thorough treatment for some tough material that has remained an obstacle to teaching and learning the subject matter. The treatment is straightforward and hence could be particularly suitable for self-study. Selected solutions are available electronically for instructors only. Please send email to textbooks@ams.org for more informatio...

A comparative study of voltage stability indices in a power system

Energy Technology Data Exchange (ETDEWEB)

Sinha, A.K. [I.I.T., Kharagpur (India). Dept. of Electrical Engineering; Hazarika, D. [Assam Engineering College (India)

2000-11-01

The paper compares the effectiveness of voltage stability indices in providing information about the proximity of voltage instability of a power system. Three simple voltage stability indices are proposed and their effectiveness is compared with some of the recently proposed indices. The comparison is carried out over a wide range of system operating conditions by changing the load power factor and feeder X/R ratios. Test results for the IEEE 57 bus and IEEE 118 bus system are presented. (author)

Stability of time-delay systems via Lyapunov functions

Directory of Open Access Journals (Sweden)

Carlos F. Alastruey

2002-01-01

Full Text Available In this paper, a Lyapunov function candidate is introduced for multivariable systems with inner delays, without assuming a priori stability for the nondelayed subsystem. By using this Lyapunov function, a controller is deduced. Such a controller utilizes an input–output description of the original system, a circumstance that facilitates practical applications of the proposed approach.

Tear film stability analysis system: introducing a new application for videokeratography.

Science.gov (United States)

Goto, Tomoko; Zheng, Xiaodong; Okamoto, Shigeki; Ohashi, Yuichi

2004-11-01

To review our previous studies regarding the development of a tear stability analysis system (TSAS) using videokeratography and the clinical application of TSAS for evaluation of tear film stability in patients subject to laser in situ keratomileusis (LASIK). New software, namely TSAS, was developed for the videokeratography system TMS-2N (topographic modeling system). TSAS automatically captures consecutive corneal surface images every second for 10 seconds. Corneal topographs were analyzed for tear breakup time (TMS-BUT) and tear breakup area (TMS-BUA, the ratio of breakup area to entire color-code area). First, we recruited volunteers to test the sensitivity and specificity of this new system in comparison with the routine method for tear stability analysis, tear film breakup time evaluation by slit-lamp microscope (SLE-BUT), with fluorescence staining. Second, we investigated the practicability of TSAS in dynamic evaluation of tear film stability before and after LASIK. TMS-BUT had a positive correlation with SLE-BUT, whereas TMS-BUA showed a negative correlation. Although they showed similar rates of specificity as SLE-BUT, the sensitivity rates of TMS-BUT and TMS-BUA were 97.5% and 95%, respectively, significantly higher than that of SLE-BUT (75%). The study on patients subject to LASIK showed that tear film stability significantly decreased during the early time period following LASIK and resolved at 6 months after surgery. Eyes that had abnormal TSAS evaluation tended to have higher risk of developing superficial punctuate keratitis and dry eye symptoms after LASIK, and their responses to treatment were slow. TSAS is a noninvasive and objective method with higher sensitivity for tear film stability analysis than SLE-BUT.

Small disturbance voltage stability assessment of power systems by modal analysis and dynamic simulation

International Nuclear Information System (INIS)

Amjady, Nima; Ansari, Mohammad Reza

2008-01-01

The introduction of liberalized electricity markets in many countries has resulted in more highly stressed power systems. On the other hand, operating points of a power system are acceptable in the feasible region, which is surrounded by the borders of different stabilities. Power system instability is critical for all participants of the electricity market. Determination of different stability margins can result in the optimum utilization of power system with minimum risk. This paper focuses on the small disturbance voltage stability, which is an important subset of the power system global stability. This kind of voltage stability is usually evaluated by static analysis tools such as continuation power flow, while it essentially has dynamic nature. Besides, a combination of linear and nonlinear analysis tools is required to correctly analyze it. In this paper, a hybrid evaluation method composed of static, dynamic, linear, and nonlinear analysis tools is proposed for this purpose. Effect of load scenario, generation pattern, branch and generator contingency on the small disturbance voltage stability are evaluated by the hybrid method. The test results are given for New England and IEEE68 bus test systems. (author)

Exponential stability of switched linear systems with time-varying delay

Directory of Open Access Journals (Sweden)

Satiracoo Pairote

2007-11-01

Full Text Available We use a Lyapunov-Krasovskii functional approach to establish the exponential stability of linear systems with time-varying delay. Our delay-dependent condition allows to compute simultaneously the two bounds that characterize the exponential stability rate of the solution. A simple procedure for constructing switching rule is also presented.

Stability of DC Voltage Droop Controllers in VSC HVDC Systems

DEFF Research Database (Denmark)

Thams, Florian; Suul, Jon Are; D’Arco, Salvatore

2015-01-01

Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC-based conver......Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC...

Absolute stability of nonlinear systems with time delays and applications to neural networks

Directory of Open Access Journals (Sweden)

Xinzhi Liu

2001-01-01

Full Text Available In this paper, absolute stability of nonlinear systems with time delays is investigated. Sufficient conditions on absolute stability are derived by using the comparison principle and differential inequalities. These conditions are simple and easy to check. In addition, exponential stability conditions for some special cases of nonlinear delay systems are discussed. Applications of those results to cellular neural networks are presented.

FINANCIAL STABILITY OF THE UKRAINE NATIONAL SYSTEM OF PENSION INSURANCE

Directory of Open Access Journals (Sweden)

A. Khemii

2014-03-01

Full Text Available The system of pension insurance is a combination of created by the state legal, economic and organizational institutions and norms, providing financial support to citizens in the form of pensions. In the article analyzing the demographic situation and the condition of pension payments in the country today. In the terms of economic and social reforms, the level of financial stability the pension system is low. Therefore important is the analysis and exploring new methods to ensure financial stability of the Ukraine national system of pension insurance. The main institution of the national pension insurance is the National Pension Fund of Ukraine.

On the stability of non-linear systems; Sur la stabilite des systemes non-lineaires

Energy Technology Data Exchange (ETDEWEB)

Guelman, M [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, services scientifiques

1968-09-01

A study is made of the absolute stability of nonlinear systems, using Liapounov's second method and taking into account the results obtained from V.M. Popov's work. The results already established are first presented, in particular concerning the frequency domain criterions for absolute stability of automatic control systems containing one single non linearity. The results have been extended to show the existence of a limiting parabola. New use is then made of the methods studied for deriving absolute stability criterions for a system containing a different type of non linearity. Finally, the results obtained are considered from the point of view of Aizerman's conjecture. (author) [French] Dans ce travail, on etudie la stabilite absolue des systemes non lineaires utilisant la deuxieme methode de Liapounov en tenant compte des resultats acquis a partir des travaux de V.M. Popov. On fait d'abord un expose des resultats deja etablis, en particulier en ce qui concerne les criteres frequentiels de stabilite absolue pour le cas d'un systeme de commande automatique comportant une seule non linearite. On a prolonge ces resultats jusqu'a l'etablissement de l'existence d'une parabole limite. On fait ensuite une nouvelle utilisation des methodes etudiees, etablissant des criteres de stabilite absolue pour un systeme comportant un type different de non linearite. On etudie enfin les resultats obtenus, dans l'optique de la conjecture de Aizerman. (auteur)

A Design of Power System Stabilization for SVC System Using a RVEGA

Energy Technology Data Exchange (ETDEWEB)

Chung, Hyeng Hwan; Hur, Dong Ryol; Lee, Jeong Phil; Wang, Yong Peel [Dong-A University, Pusan (Korea)

2001-07-01

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer (PSS) with robustness in low frequency oscillation for Static VAR Compensator (SVC) using a Real Variable Elitism Genetic Algorithm (RVEGA). A SVE, one of the Flexible AC Transmission System (FACTS), constructed by a fixed capacitor (FC) and a thyristor controlled reactor (TCR), is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage. The proposed PSS parameters are optimized using RVEGA in order to maintain optimal operation of generator under the various operating conditions. To decrease the computational time, real variable string is adopted. To verify the robustness of the proposed method, we considered the dynamic response of generator speed deviation and generator terminal voltage by applying a power fluctuation and three-phase fault at heavy load, normal load and light load. Thus, we prove the usefulness of proposed method to improve the stability of single machine-infinite bus with SVC system. (author). 20 refs., 14 figs., 3 tabs.

Delay-dependent asymptotic stability of mobile ad-hoc networks: A descriptor system approach

International Nuclear Information System (INIS)

Yang Juan; Yang Dan; Zhang Xiao-Hong; Huang Bin; Luo Jian-Lu

2014-01-01

In order to analyze the capacity stability of the time-varying-propagation and delay-dependent of mobile ad-hoc networks (MANETs), in this paper, a novel approach is proposed to explore the capacity asymptotic stability for the delay-dependent of MANETs based on non-cooperative game theory, where the delay-dependent conditions are explicitly taken into consideration. This approach is based on the Lyapunov—Krasovskii stability theory for functional differential equations and the linear matrix inequality (LMI) technique. A corresponding Lyapunov—Krasovskii functional is introduced for the stability analysis of this system with use of the descriptor and “neutral-type” model transformation without producing any additional dynamics. The delay-dependent stability criteria are derived for this system. Conditions are given in terms of linear matrix inequalities, and for the first time referred to neutral systems with the time-varying propagation and delay-dependent stability for capacity analysis of MANETs. The proposed criteria are less conservative since they are based on an equivalent model transformation. Furthermore, we also provide an effective and efficient iterative algorithm to solve the constrained stability control model. Simulation experiments have verified the effectiveness and efficiency of our algorithm. (general)

SU-F-P-11: Long Term Dosimetric Stability of 6 TomoTherapy Systems

Energy Technology Data Exchange (ETDEWEB)

Smilowitz, J; Dunkerley, D; Geurts, M; Hill, P; Yadav, P [University of Wisconsin, Madison, WI (United States)

2016-06-15

Purpose: The dosimetric stability of six TomoTherapy units was analyzed to investigate changes in performance over time and with system upgrades. Methods: Energy and output were tracked using monitor chamber signal, onboard MVCT detector signal and external ion chamber measurements. The systems (and monitoring periods) include 3 Hi-Art (67, 61 and 65 mos.), 2 HDA (29 and 25 mos.) and one research unit (7 mo.). Dose Control Stability system (DCS) was installed on 4 systems. Output stability is reported as deviation from reference monitor chamber signal for all systems, and from an external chamber for 4 systems. Energy stability was monitored using the relative (center versus off-axis) MVCT detector signal and/or the ratio of chamber measurements at 2 depths. The results from the clinical systems were used to benchmark the stability of the research unit, which has the same linear accelerator but runs at a higher dose rate. Results: The output based on monitor chamber data of all six systems is very stable. Non- DCS had a standard deviation of 1.7% and 1.8%. As expected, DCS systems had improved standard deviation: 0.003–0.05%. The energy was also very stable for all units. The standard deviation in exit detector flatness was 0.02–0.3%. Ion chamber output and 20/10 cm ratios supported these results. The stability for the research system, as monitored with a variety of metrics, is on par with the existing systems. Conclusion: The output and energy of six TomoTherapy units over a total of almost 10 years is quite stable. For each system, the results are consistent between the different measurement tools and techniques, proving not only the dosimetric stability, but that these quality parameters can be confirmed with various metrics. A research unit operating at a higher dose rate performed as well as the clinical treatment units. University of Wisconsin and Accuray Inc. (vendor of TomoTherapy systems) have a research agreement which supplies funds for research to

Stability of power systems coupled with market dynamics

Science.gov (United States)

Meng, Jianping

This Ph.D. thesis presented here spans two relatively independent topics. The first part, Chapter 2 is self-contained, and is dedicated to studies of new algorithms for power system state estimation. The second part, encompassing the remaining chapters, is dedicated to stability analysis of power system coupled with market dynamics. The first part of this thesis presents improved Newton's methods employing efficient vectorized calculations of higher order derivatives in power system state estimation problems. The improved algorithms are proposed based on an exact Newton's method using the second order terms. By efficiently computing an exact gain matrix, combined with a special optimal multiplier method, the new algorithms show more reliable convergence compared with the existing methods of normal equations, orthogonal decomposition, and Hachtel's sparse tableau. Our methods are able to handle ill-conditioned problems, yet show minimal penalty in computational cost for well-conditioned cases. These claims are illustrated through the standard IEEE 118 and 300 bus test examples. The second part of the thesis focuses on stability analysis of market/power systems. The work presented is motivated by an emerging problem. As the frequency of market based dispatch updates increases, there will inevitably be interaction between the dynamics of markets determining the generator dispatch commands, and the physical response of generators and network interconnections, necessitating the development of stability analysis for such coupled systems. We begin with numeric tests using different market models, with detailed machine/exciter/turbine/governor dynamics, in the New England 39 bus test system. A progression of modeling refinements are introduced, including such non-ideal effects as time delays. Electricity market parameter identification algorithms are also studied based on real time data from the PJM electricity market. Finally our power market model is augmented by optimal

A Gimbal-Stabilized Compact Hyperspectral Imaging System, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Gimbal-stabilized Compact Hyperspectral Imaging System (GCHIS) fully integrates multi-sensor spectral imaging, stereovision, GPS and inertial measurement,...

The conditions for attaining the greatest degree of system stability with strict generator excitation control

Energy Technology Data Exchange (ETDEWEB)

Gruzdev, I.A.; Ekimova, M.M.; Truspekova, G.A.

1982-01-01

Expressions are derived for an idealized model of a complex electric power system; these expressions define the greatest level of stability of an electric power system and the optimum combination of stabilization factors with automatic excitation control in a single power system. The possibility of increasing the level of stability of an electric power system with simultaneous strict automatic excitation control of the synychronous generators in several power systems is analyzed.

Security region-based small signal stability analysis of power systems with FSIG based wind farm

Science.gov (United States)

Qin, Chao; Zeng, Yuan; Yang, Yang; Cui, Xiaodan; Xu, Xialing; Li, Yong

2018-02-01

Based on the Security Region approach, the impact of fixed-speed induction generator based wind farm on the small signal stability of power systems is analyzed. Firstly, the key factors of wind farm on the small signal stability of power systems are analyzed and the parameter space for small signal stability region is formed. Secondly, the small signal stability region of power systems with wind power is established. Thirdly, the corresponding relation between the boundary of SSSR and the dominant oscillation mode is further studied. Results show that the integration of fixed-speed induction generator based wind farm will cause the low frequency oscillation stability of the power system deteriorate. When the output of wind power is high, the oscillation stability of the power system is mainly concerned with the inter-area oscillation mode caused by the integration of the wind farm. Both the active power output and the capacity of reactive power compensation of the wind farm have a significant influence on the SSSR. To improve the oscillation stability of power systems with wind power, it is suggested to reasonably set the reactive power compensation capacity for the wind farm through SSSR.

Optimal Subinterval Selection Approach for Power System Transient Stability Simulation

Directory of Open Access Journals (Sweden)

Soobae Kim

2015-10-01

Full Text Available Power system transient stability analysis requires an appropriate integration time step to avoid numerical instability as well as to reduce computational demands. For fast system dynamics, which vary more rapidly than what the time step covers, a fraction of the time step, called a subinterval, is used. However, the optimal value of this subinterval is not easily determined because the analysis of the system dynamics might be required. This selection is usually made from engineering experiences, and perhaps trial and error. This paper proposes an optimal subinterval selection approach for power system transient stability analysis, which is based on modal analysis using a single machine infinite bus (SMIB system. Fast system dynamics are identified with the modal analysis and the SMIB system is used focusing on fast local modes. An appropriate subinterval time step from the proposed approach can reduce computational burden and achieve accurate simulation responses as well. The performance of the proposed method is demonstrated with the GSO 37-bus system.

Distributed-Order Dynamic Systems Stability, Simulation, Applications and Perspectives

CERN Document Server

Jiao, Zhuang; Podlubny, Igor

2012-01-01

Distributed-order differential equations, a generalization of fractional calculus, are of increasing importance in many fields of science and engineering from the behaviour of complex dielectric media to the modelling of nonlinear systems. This Brief will broaden the toolbox available to researchers interested in modeling, analysis, control and filtering. It contains contextual material outlining the progression from integer-order, through fractional-order to distributed-order systems. Stability issues are addressed with graphical and numerical results highlighting the fundamental differences between constant-, integer-, and distributed-order treatments. The power of the distributed-order model is demonstrated with work on the stability of noncommensurate-order linear time-invariant systems. Generic applications of the distributed-order operator follow: signal processing and viscoelastic damping of a mass–spring set up. A new general approach to discretization of distributed-order derivatives and integrals ...

Stability of Nonlinear Systems with Unknown Time-varying Feedback Delay

Science.gov (United States)

Chunodkar, Apurva A.; Akella, Maruthi R.

2013-12-01

This paper considers the problem of stabilizing a class of nonlinear systems with unknown bounded delayed feedback wherein the time-varying delay is 1) piecewise constant 2) continuous with a bounded rate. We also consider application of these results to the stabilization of rigid-body attitude dynamics. In the first case, the time-delay in feedback is modeled specifically as a switch among an arbitrarily large set of unknown constant values with a known strict upper bound. The feedback is a linear function of the delayed states. In the case of linear systems with switched delay feedback, a new sufficiency condition for average dwell time result is presented using a complete type Lyapunov-Krasovskii (L-K) functional approach. Further, the corresponding switched system with nonlinear perturbations is proven to be exponentially stable inside a well characterized region of attraction for an appropriately chosen average dwell time. In the second case, the concept of the complete type L-K functional is extended to a class of nonlinear time-delay systems with unknown time-varying time-delay. This extension ensures stability robustness to time-delay in the control design for all values of time-delay less than the known upper bound. Model-transformation is used in order to partition the nonlinear system into a nominal linear part that is exponentially stable with a bounded perturbation. We obtain sufficient conditions which ensure exponential stability inside a region of attraction estimate. A constructive method to evaluate the sufficient conditions is presented together with comparison with the corresponding constant and piecewise constant delay. Numerical simulations are performed to illustrate the theoretical results of this paper.

Stabilization of computational procedures for constrained dynamical systems

Science.gov (United States)

Park, K. C.; Chiou, J. C.

1988-01-01

A new stabilization method of treating constraints in multibody dynamical systems is presented. By tailoring a penalty form of the constraint equations, the method achieves stabilization without artificial damping and yields a companion matrix differential equation for the constraint forces; hence, the constraint forces are obtained by integrating the companion differential equation for the constraint forces in time. A principal feature of the method is that the errors committed in each constraint condition decay with its corresponding characteristic time scale associated with its constraint force. Numerical experiments indicate that the method yields a marked improvement over existing techniques.

Global Uniform Asymptotic Stability of a Class of Switched Linear Systems with an Infinite Number of Subsystems

Directory of Open Access Journals (Sweden)

L. F. Araghi

2014-01-01

Full Text Available Stability of switching systems with an infinite number of subsystems is important in some structure of systems, like fuzzy systems, neural networks, and so forth. Because of the relationship between stability of a set of matrices and switching systems, this paper first studies the stability of a set of matrices, then and the results are applied for stability of switching systems. Some new conditions for globally uniformly asymptotically stability (GUAS of discrete-time switched linear systems with an infinite number of subsystems are proposed. The paper considers some examples and simulation results.

The nekhoroshev theorem and long-term stabilities in the solar system

Directory of Open Access Journals (Sweden)

Guzzo M.

2015-01-01

Full Text Available The Nekhoroshev theorem has been often indicated in the last decades as the reference theorem for explaining the dynamics of several systems which are stable in the long-term. The Solar System dynamics provides a wide range of possible and useful applications. In fact, despite the complicated models which are used to numerically integrate realistic Solar System dynamics as accurately as possible, when the integrated solutions are chaotic the reliability of the numerical integrations is limited, and a theoretical long-term stability analysis is required. After the first formulation of Nekhoroshev’s theorem in 1977, many theoretical improvements have been achieved. On the one hand, alternative proofs of the theorem itself led to consistent improvements of the stability estimates; on the other hand, the extensions which were necessary to apply the theorem to the systems of interest for Solar System Dynamics, in particular concerning the removal of degeneracies and the implementation of computer assisted proofs, have been developed. In this review paper we discuss some of the motivations and the results which have made Nekhoroshev’s theorem a reference stability result for many applications in the Solar System dynamics.

Stability Analysis of a Reaction-Diffusion System Modeling Atherogenesis

KAUST Repository

Ibragimov, Akif

2010-01-01

This paper presents a linear, asymptotic stability analysis for a reaction-diffusionconvection system modeling atherogenesis, the initiation of atherosclerosis, as an inflammatory instability. Motivated by the disease paradigm articulated by Ross, atherogenesis is viewed as an inflammatory spiral with a positive feedback loop involving key cellular and chemical species interacting and reacting within the intimal layer of muscular arteries. The inflammatory spiral is initiated as an instability from a healthy state which is defined to be an equilibrium state devoid of certain key inflammatory markers. Disease initiation is studied through a linear, asymptotic stability analysis of a healthy equilibrium state. Various theorems are proved, giving conditions on system parameters guaranteeing stability of the health state, and a general framework is developed for constructing perturbations from a healthy state that exhibit blow-up, which are interpreted as corresponding to disease initiation. The analysis reveals key features that arterial geometry, antioxidant levels, and the source of inflammatory components (through coupled third-kind boundary conditions or through body sources) play in disease initiation. © 2010 Society for Industrial and Applied Mathematics.

On Some Sufficiency-Type Stability and Linear State-Feedback Stabilization Conditions for a Class of Multirate Discrete-Time Systems

Directory of Open Access Journals (Sweden)

M. De la Sen

2018-05-01

Full Text Available This paper presents and discusses the stability of a discrete multirate sampling system whose sets of sampling rates (or sampling periods are the integer multiple of those operating on all the preceding substates. Each of such substates is associated with a particular sampling rate. The sufficiency-type stability conditions are derived based on simple conditions on the norm, spectral radius and numerical radius of the matrix of the dynamics of a system parameterized at the largest sampling period.

Fast simulation of wind generation for frequency stability analysis in island power systems

Energy Technology Data Exchange (ETDEWEB)

Conroy, James [EirGrid, Dublin (Ireland)

2010-07-01

Frequency stability is a major issue for power system planning and operation in an island power system such as Ireland. As increasing amounts of variable speed wind generation are added to the system, this issue becomes more prominent, as variable speed wind generation does not provide an inherent inertial response. This lack of an inertial response means that simplified models for variable speed wind farms can be used for investigating frequency stability. EirGrid uses DIgSILENT Power Factory (as well as other software tools) to investigate frequency stability. In PowerFactory, an automation program has been created to convert detailed wind farm representation (as necessary for other types of analysis) to negative load models for frequency stability analysis. The advantage of this approach is much-improved simulation speed without loss of accuracy. This approach can also be to study future wind energy targets, and long-term simulation of voltage stability. (orig.)

On partial stabilization of a system of the Euler-Bernoulli beam equations

International Nuclear Information System (INIS)

Zuyev, Alexander

2003-11-01

The paper is focused on the stabilization problem for the following system of differential equations ∂ 2 (t) = v, t ≥ 0, (∂ 2 ω i (x,t))/∂t 2 + c 2 (∂ 4 ω i (x,t))/∂x 4 = ∂ 2 (t)ω i (x,t) - (x+d)v, x is an element of [0,l], i = 1,2,...,k, where v is an element of R is the control parameter. The above system describes a rotating rigid body endowed with a number of elastic beams. To solve the stabilization problem, we prove a sufficient condition for partial strong asymptotic stability which is valid for general nonlinear dynamical systems in a Banach space. This result is applied to deriving a feedback control explicitly. In addition, we prove strong (non-asymptotic) stability in the sense of Lyapunov as well as precompacness of the trajectories for the corresponding nonlinear semigroup. Some simulation results are given in conclusion. (author)

Stability analysis of switched linear systems defined by graphs

OpenAIRE

Athanasopoulos, Nikolaos; Lazar, Mircea

2015-01-01

We present necessary and sufficient conditions for global exponential stability for switched discrete-time linear systems, under arbitrary switching, which is constrained within a set of admissible transitions. The class of systems studied includes the family of systems under arbitrary switching, periodic systems, and systems with minimum and maximum dwell time specifications. To reach the result, we describe the set of rules that define the admissible transitions with a weighted directed gra...

Investigation on flow stability of supercritical water cooled systems

International Nuclear Information System (INIS)

Cheng, X.; Kuang, B.

2006-01-01

Research activities are ongoing worldwide to develop nuclear power plants with supercritical water cooled reactor (SCWR) with the purpose to achieve a high thermal efficiency and to improve their economical competitiveness. However, the strong variation of the thermal-physical properties of water in the vicinity of the pseudo-critical line results in challenging tasks in various fields, e.g. thermal-hydraulic design of a SCWR. One of the challenging tasks is to understand and to predict the dynamic behavior of supercritical water cooled systems. Although many thermal-hydraulic research activities were carried out worldwide in the past as well as in the near present, studies on dynamic behavior and flow stability of SC water cooled systems are scare. Due to the strong density variation, flow stability is expected to be one of the key items which need to be taken into account in the design of a SCWR. In the present work, the dynamic behavior and flow stability of SC water cooled systems are investigated using both numerical and theoretical approaches. For this purpose a new computer code SASC was developed, which can be applied to analysis the dynamic behavior of systems cooled by supercritical fluids. In addition, based on the assumptions of a simplified system, a theoretical model was derived for the prediction of the onset of flow instability. A comparison was made between the results obtained using the theoretical model and those from the SASC code. A good agreement was achieved. This gives the first evidence of the reliability of both the SASC code and the theoretical model

Asymptotic stability and disturbance attenuation properties for a class of networked control systems

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

In this paper, stability and disturbance attenuation issues for a class of Networked Control Systems (NCSs)under uncertain access delay and packet dropout effects are considered. Our aim is to find conditions on the delay and packet dropout rate, under which the system stability and H∞ disturbance attenuation properties are preserved to a desired level. The basic idea in this paper is to formulate such Networked Control System as a discrete-time switched system. Then the NCSs' stability and performance problems can be reduced to the corresponding problems for switched systems, which have been studied for decades and for which a number of results are available in the literature. The techniques in this paper are based on recent progress in the discrete-time switched systems and piecewise Lyapunov functions.

Robust stability analysis of large power systems using the structured singular value theory

Energy Technology Data Exchange (ETDEWEB)

Castellanos, R.; Sarmiento, H. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Messina, A.R. [Cinvestav, Graduate Program in Electrical Engineering, Guadalajara, Jalisco (Mexico)

2005-07-01

This paper examines the application of structured singular value (SSV) theory to analyse robust stability of complex power systems with respect to a set of structured uncertainties. Based on SSV theory and the frequency sweep method, techniques for robust analysis of large-scale power systems are developed. The main interest is focused on determining robust stability for varying operating conditions and uncertainties in the structure of the power system. The applicability of the proposed techniques is verified through simulation studies on a large-scale power system. In particular, results for the system are considered for a wide range of uncertainties of operating conditions. Specifically, the developed technique is used to estimate the effect of variations in the parameters of a major system inter-tie on the nominal stability of a critical inter-area mode. (Author)

Algorithm for Stabilizing a POD-Based Dynamical System

Science.gov (United States)

Kalb, Virginia L.

2010-01-01

This algorithm provides a new way to improve the accuracy and asymptotic behavior of a low-dimensional system based on the proper orthogonal decomposition (POD). Given a data set representing the evolution of a system of partial differential equations (PDEs), such as the Navier-Stokes equations for incompressible flow, one may obtain a low-dimensional model in the form of ordinary differential equations (ODEs) that should model the dynamics of the flow. Temporal sampling of the direct numerical simulation of the PDEs produces a spatial time series. The POD extracts the temporal and spatial eigenfunctions of this data set. Truncated to retain only the most energetic modes followed by Galerkin projection of these modes onto the PDEs obtains a dynamical system of ordinary differential equations for the time-dependent behavior of the flow. In practice, the steps leading to this system of ODEs entail numerically computing first-order derivatives of the mean data field and the eigenfunctions, and the computation of many inner products. This is far from a perfect process, and often results in the lack of long-term stability of the system and incorrect asymptotic behavior of the model. This algorithm describes a new stabilization method that utilizes the temporal eigenfunctions to derive correction terms for the coefficients of the dynamical system to significantly reduce these errors.

Results on stabilization of nonlinear systems under finite data-rate constraints

NARCIS (Netherlands)

Persis, Claudio De

2004-01-01

We discuss in this paper a result concerning the stabilization problem of nonlinear systems under data-rate constraints using output feedback. To put the result in a broader context, we shall first review a number of recent contributions on the stabilization problem under data-rate constraints when

Robust Stabilization of Nonlinear Systems with Uncertain Varying Control Coefficient

Directory of Open Access Journals (Sweden)

Zaiyue Yang

2014-01-01

Full Text Available This paper investigates the stabilization problem for a class of nonlinear systems, whose control coefficient is uncertain and varies continuously in value and sign. The study emphasizes the development of a robust control that consists of a modified Nussbaum function to tackle the uncertain varying control coefficient. By such a method, the finite-time escape phenomenon has been prevented when the control coefficient is crossing zero and varying its sign. The proposed control guarantees the asymptotic stabilization of the system and boundedness of all closed-loop signals. The control performance is illustrated by a numerical simulation.

Stabilization of periodic solutions in a tethered satellite system by damping injection

DEFF Research Database (Denmark)

Larsen, Martin Birkelund; Blanke, Mogens

2009-01-01

presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilizing the open-loop equilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether...... to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational...

Stability Control of Force-Reflected Nonlinear Multilateral Teleoperation System under Time-Varying Delays

Directory of Open Access Journals (Sweden)

Da Sun

2016-01-01

Full Text Available A novel control algorithm based on the modified wave-variable controllers is proposed to achieve accurate position synchronization and reasonable force tracking of the nonlinear single-master-multiple-slave teleoperation system and simultaneously guarantee overall system’s stability in the presence of large time-varying delays. The system stability in different scenarios of human and environment situations has been analyzed. The proposed method is validated through experimental work based on the 3-DOF trilateral teleoperation system consisting of three different manipulators. The experimental results clearly demonstrate the feasibility of the proposed algorithm to achieve high transparency and robust stability in nonlinear single-master-multiple-slave teleoperation system in the presence of time-varying delays.

Stability analysis of nonlinear Roesser-type two-dimensional systems via a homogenous polynomial technique

Science.gov (United States)

Zhang, Tie-Yan; Zhao, Yan; Xie, Xiang-Peng

2012-12-01

This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional (2D) systems. Firstly, the fuzzy modeling method for the usual one-dimensional (1D) systems is extended to the 2D case so that the underlying nonlinear 2D system can be represented by the 2D Takagi—Sugeno (TS) fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conservative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach.

Stability analysis of nonlinear Roesser-type two-dimensional systems via a homogenous polynomial technique

International Nuclear Information System (INIS)

Zhang Tie-Yan; Zhao Yan; Xie Xiang-Peng

2012-01-01

This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional (2D) systems. Firstly, the fuzzy modeling method for the usual one-dimensional (1D) systems is extended to the 2D case so that the underlying nonlinear 2D system can be represented by the 2D Takagi—Sugeno (TS) fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conservative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach. (general)

Nonlinear stability research on the hydraulic system of double-side rolling shear

Science.gov (United States)

Wang, Jun; Huang, Qingxue; An, Gaocheng; Qi, Qisong; Sun, Binyu

2015-10-01

This paper researches the stability of the nonlinear system taking the hydraulic system of double-side rolling shear as an example. The hydraulic system of double-side rolling shear uses unsymmetrical electro-hydraulic proportional servo valve to control the cylinder with single piston rod, which can make best use of the space and reduce reversing shock. It is a typical nonlinear structure. The nonlinear state-space equations of the unsymmetrical valve controlling cylinder system are built first, and the second Lyapunov method is used to evaluate its stability. Second, the software AMEsim is applied to simulate the nonlinear system, and the results indicate that the system is stable. At last, the experimental results show that the system unsymmetrical valve controlling the cylinder with single piston rod is stable and conforms to what is deduced by theoretical analysis and simulation. The construction and application of Lyapunov function not only provide the theoretical basis for using of unsymmetrical valve controlling cylinder with single piston rod but also develop a new thought for nonlinear stability evaluation.

Los estudios culturales en Centroamérica.

OpenAIRE

Fumero, Patricia

2012-01-01

En el presente artículo se considerará el inicio de los estudios culturales en Centroamérica y las diversas corrientes que influyeron en este cambio. Posteriormente, se analizará la problemática que supone el estudio del istmo, en términos de su diversidad y del desarrollo de adecuadas perspectivas comparativas. Por último, se revisarán los avances logrados por los estudios literarios y los desafíos planteados en el futuro inmediato.

Stability of Polyphenols Epigallocatechin Gallate and Pentagalloyl Glucose in a Simulated Digestive System

Science.gov (United States)

Krook, Melanie A.; Hagerman, Ann E.

2012-01-01

Polyphenols found in foods and beverages are under intense scrutiny for their potential beneficial effects on human health. We examined the stability of two bioactive polyphenols, epigallocatechin-O-gallate (EGCg) and 1,2,3,4,6-penta-O-galloyl-β-D-glucopyranose (PGG), in a model digestive system at low oxygen tension with and without added digestive components and foods. Both compounds were stable at pH values of 5–6 and below, indicating gastric stability. Both compounds decomposed at pH 7.0. PGG was stabilized in a model system containing pepsin, pancreatin, bile and lipase, and/or baby food, but was not stabilized by dry cereal. EGCg was not stabilized by the addition of any biomolecule. The effects of polyphenols on human health should be evaluated in the context of their stability in the digestive tract with and without added digestive components and/or food. PMID:23028206

The Absolute Stability Analysis in Fuzzy Control Systems with Parametric Uncertainties and Reference Inputs

Science.gov (United States)

Wu, Bing-Fei; Ma, Li-Shan; Perng, Jau-Woei

This study analyzes the absolute stability in P and PD type fuzzy logic control systems with both certain and uncertain linear plants. Stability analysis includes the reference input, actuator gain and interval plant parameters. For certain linear plants, the stability (i.e. the stable equilibriums of error) in P and PD types is analyzed with the Popov or linearization methods under various reference inputs and actuator gains. The steady state errors of fuzzy control systems are also addressed in the parameter plane. The parametric robust Popov criterion for parametric absolute stability based on Lur'e systems is also applied to the stability analysis of P type fuzzy control systems with uncertain plants. The PD type fuzzy logic controller in our approach is a single-input fuzzy logic controller and is transformed into the P type for analysis. In our work, the absolute stability analysis of fuzzy control systems is given with respect to a non-zero reference input and an uncertain linear plant with the parametric robust Popov criterion unlike previous works. Moreover, a fuzzy current controlled RC circuit is designed with PSPICE models. Both numerical and PSPICE simulations are provided to verify the analytical results. Furthermore, the oscillation mechanism in fuzzy control systems is specified with various equilibrium points of view in the simulation example. Finally, the comparisons are also given to show the effectiveness of the analysis method.

Very high stability systems: LMJ target alignment system and MTG imager test setup

Science.gov (United States)

Compain, Eric; Maquet, Philippe; Kunc, Thierry; Marque, Julien; Lauer-Solelhac, Maxime; Delage, Laurent; Lanternier, Catherine

2015-09-01

Most of space instruments and research facilities require test equipment with demanding opto-mechanical stability. In some specific cases, when the stability performance directly drives the final performance of the scientific mission and when feasibility is questionable, specific methods must be implemented for the associated technical risk management. In present paper, we will present our heritage in terms of methodology, design, test and the associated results for two specific systems : the SOPAC-POS and the MOTA, generating new references for future developments. From a performance point of view, we will emphasis on following key parameters : design symmetry, thermal load management, and material and structural choices. From a method point of view the difficulties arise first during design, from the strong coupling between the thermal, mechanical and optical performance models, and then during testing, from the difficulty of conceiving test setup having appropriate performance level. We will present how these limitations have been overcome. SOPAC-POS is the target alignment system of the LMJ, Laser Mega Joule, the French inertial confinement fusion research center. Its stability has been demonstrated by tests in 2014 after 10 years of research and development activities, achieving 1μm stability @ 6m during one hour periods. MOTA is an Optical Ground Support Equipment aiming at qualifying by tests the Flexible Combined Imager (FCI). FCI is an instrument for the meteorological satellite MTG-I, a program of and funded by the European Space Agency and under prime contractorship of Thales Alenia Space. Optimized design will allow to get better than 0.2 μrad stability for one hour periods, as required for MTF measurement.

LMI-based stability and performance conditions for continuous-time nonlinear systems in Takagi-Sugeno's form.

Science.gov (United States)

Lam, H K; Leung, Frank H F

2007-10-01

This correspondence presents the stability analysis and performance design of the continuous-time fuzzy-model-based control systems. The idea of the nonparallel-distributed-compensation (non-PDC) control laws is extended to the continuous-time fuzzy-model-based control systems. A nonlinear controller with non-PDC control laws is proposed to stabilize the continuous-time nonlinear systems in Takagi-Sugeno's form. To produce the stability-analysis result, a parameter-dependent Lyapunov function (PDLF) is employed. However, two difficulties are usually encountered: 1) the time-derivative terms produced by the PDLF will complicate the stability analysis and 2) the stability conditions are not in the form of linear-matrix inequalities (LMIs) that aid the design of feedback gains. To tackle the first difficulty, the time-derivative terms are represented by some weighted-sum terms in some existing approaches, which will increase the number of stability conditions significantly. In view of the second difficulty, some positive-definitive terms are added in order to cast the stability conditions into LMIs. In this correspondence, the favorable properties of the membership functions and nonlinear control laws, which allow the introduction of some free matrices, are employed to alleviate the two difficulties while retaining the favorable properties of PDLF-based approach. LMI-based stability conditions are derived to ensure the system stability. Furthermore, based on a common scalar performance index, LMI-based performance conditions are derived to guarantee the system performance. Simulation examples are given to illustrate the effectiveness of the proposed approach.

Stabilization of Networked Control Systems Under Feedback-based Communication

National Research Council Canada - National Science Library

Zhang, Lei; Hristu-Varsakelis, Dimitrios

2004-01-01

We study the stabilization of a networked control system (NSC) in which multiple sensors and actuators of a physical plant share a communication medium to exchange information with a remote controller...

Stability Analysis of a Reaction-Diffusion System Modeling Atherogenesis

KAUST Repository

Ibragimov, Akif; Ritter, Laura; Walton, Jay R.

2010-01-01

This paper presents a linear, asymptotic stability analysis for a reaction-diffusionconvection system modeling atherogenesis, the initiation of atherosclerosis, as an inflammatory instability. Motivated by the disease paradigm articulated by Ross

Adaptive neural networks control for camera stabilization with active suspension system

Directory of Open Access Journals (Sweden)

Feng Zhao

2015-08-01

Full Text Available The camera always suffers from image instability on the moving vehicle due to unintentional vibrations caused by road roughness. This article presents an adaptive neural network approach mixed with linear quadratic regulator control for a quarter-car active suspension system to stabilize the image captured area of the camera. An active suspension system provides extra force through the actuator which allows it to suppress vertical vibration of sprung mass. First, to deal with the road disturbance and the system uncertainties, radial basis function neural network is proposed to construct the map between the state error and the compensation component, which can correct the optimal state-feedback control law. The weights matrix of radial basis function neural network is adaptively tuned online. Then, the closed-loop stability and asymptotic convergence performance is guaranteed by Lyapunov analysis. Finally, the simulation results demonstrate that the proposed controller effectively suppresses the vibration of the camera and enhances the stabilization of the entire camera, where different excitations are considered to validate the system performance.

Adaptive Neural-Sliding Mode Control of Active Suspension System for Camera Stabilization

Directory of Open Access Journals (Sweden)

Feng Zhao

2015-01-01

Full Text Available The camera always suffers from image instability on the moving vehicle due to the unintentional vibrations caused by road roughness. This paper presents a novel adaptive neural network based on sliding mode control strategy to stabilize the image captured area of the camera. The purpose is to suppress vertical displacement of sprung mass with the application of active suspension system. Since the active suspension system has nonlinear and time varying characteristics, adaptive neural network (ANN is proposed to make the controller robustness against systematic uncertainties, which release the model-based requirement of the sliding model control, and the weighting matrix is adjusted online according to Lyapunov function. The control system consists of two loops. The outer loop is a position controller designed with sliding mode strategy, while the PID controller in the inner loop is to track the desired force. The closed loop stability and asymptotic convergence performance can be guaranteed on the basis of the Lyapunov stability theory. Finally, the simulation results show that the employed controller effectively suppresses the vibration of the camera and enhances the stabilization of the entire camera, where different excitations are considered to validate the system performance.

Switched periodic systems in discrete time: stability and input-output norms

Science.gov (United States)

Bolzern, Paolo; Colaneri, Patrizio

2013-07-01

This paper deals with the analysis of stability and the characterisation of input-output norms for discrete-time periodic switched linear systems. Such systems consist of a network of time-periodic linear subsystems sharing the same state vector and an exogenous switching signal that triggers the jumps between the subsystems. The overall system exhibits a complex dynamic behaviour due to the interplay between the time periodicity of the subsystem parameters and the switching signal. Both arbitrary switching signals and signals satisfying a dwell-time constraint are considered. Linear matrix inequality conditions for stability and guaranteed H2 and H∞ performances are provided. The results heavily rely on the merge of the theory of linear periodic systems and recent developments on switched linear time-invariant systems.

Stability of Nonlinear Wave Patterns to the Bipolar Vlasov-Poisson-Boltzmann System

Science.gov (United States)

Li, Hailiang; Wang, Yi; Yang, Tong; Zhong, Mingying

2018-04-01

The main purpose of the present paper is to investigate the nonlinear stability of viscous shock waves and rarefaction waves for the bipolar Vlasov-Poisson-Boltzmann (VPB) system. To this end, motivated by the micro-macro decomposition to the Boltzmann equation in Liu and Yu (Commun Math Phys 246:133-179, 2004) and Liu et al. (Physica D 188:178-192, 2004), we first set up a new micro-macro decomposition around the local Maxwellian related to the bipolar VPB system and give a unified framework to study the nonlinear stability of the basic wave patterns to the system. Then, as applications of this new decomposition, the time-asymptotic stability of the two typical nonlinear wave patterns, viscous shock waves and rarefaction waves are proved for the 1D bipolar VPB system. More precisely, it is first proved that the linear superposition of two Boltzmann shock profiles in the first and third characteristic fields is nonlinearly stable to the 1D bipolar VPB system up to some suitable shifts without the zero macroscopic mass conditions on the initial perturbations. Then the time-asymptotic stability of the rarefaction wave fan to compressible Euler equations is proved for the 1D bipolar VPB system. These two results are concerned with the nonlinear stability of wave patterns for Boltzmann equation coupled with additional (electric) forces, which together with spectral analysis made in Li et al. (Indiana Univ Math J 65(2):665-725, 2016) sheds light on understanding the complicated dynamic behaviors around the wave patterns in the transportation of charged particles under the binary collisions, mutual interactions, and the effect of the electrostatic potential forces.

Transient Stability Assessment of Power Systems With Uncertain Renewable Generation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Villegas Pico, Hugo Nestor [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Aliprantis, Dionysios C. [Purdue University; Lin, Xiaojun [Purdue University

2017-08-09

The transient stability of a power system depends heavily on its operational state at the moment of a fault. In systems where the penetration of renewable generation is significant, the dispatch of the conventional fleet of synchronous generators is uncertain at the time of dynamic security analysis. Hence, the assessment of transient stability requires the solution of a system of nonlinear ordinary differential equations with unknown initial conditions and inputs. To this end, we set forth a computational framework that relies on Taylor polynomials, where variables are associated with the level of renewable generation. This paper describes the details of the method and illustrates its application on a nine-bus test system.

Voltage Stability Bifurcation Analysis for AC/DC Systems with VSC-HVDC

Directory of Open Access Journals (Sweden)

Yanfang Wei

2013-01-01

Full Text Available A voltage stability bifurcation analysis approach for modeling AC/DC systems with VSC-HVDC is presented. The steady power model and control modes of VSC-HVDC are briefly presented firstly. Based on the steady model of VSC-HVDC, a new improved sequential iterative power flow algorithm is proposed. Then, by use of continuation power flow algorithm with the new sequential method, the voltage stability bifurcation of the system is discussed. The trace of the P-V curves and the computation of the saddle node bifurcation point of the system can be obtained. At last, the modified IEEE test systems are adopted to illustrate the effectiveness of the proposed method.

Coamorphous Loratadine-Citric Acid System with Enhanced Physical Stability and Bioavailability.

Science.gov (United States)

Wang, Jin; Chang, Ruimiao; Zhao, Yanan; Zhang, Jiye; Zhang, Ting; Fu, Qiang; Chang, Chun; Zeng, Aiguo

2017-10-01

Coamorphous systems using citric acid as a small molecular excipient were studied for improving physical stability and bioavailability of loratadine, a BCS class II drug with low water solubility and high permeability. Coamorphous loratadine-citric acid systems were prepared by solvent evaporation technique and characterized by differential scanning calorimetry, X-ray powder diffraction, and Fourier transform infrared spectroscopy. Solid-state analysis proofed that coamorphous loratadine-citric acid system (1:1) was amorphous and homogeneous, had a higher T g over amorphous loratadine, and the intermolecular hydrogen bond interactions between loratadine and citric acid exist. The solubility and dissolution of coamorphous loratadine-citric acid system (1:1) were found to be significantly greater than those of crystalline and amorphous form. The pharmacokinetic study in rats proved that coamorphous loratadine-citric acid system (1:1) could significantly improve absorption and bioavailability of loratadine. Coamorphous loratadine-citric acid system (1:1) showed excellently physical stability over a period of 3 months at 25°C under 0% RH and 25°C under 60% RH conditions. The improved stability of coamorphous loratadine-citric acid system (1:1) could be related to an elevated T g over amorphous form and the intermolecular hydrogen bond interactions between loratadine and citric acid. These studies demonstrate that the developed coamorphous loratadine-citric acid system might be a promising oral formulation for improving solubility and bioavailability of loratadine.

Students' Understanding of Equilibrium and Stability: The Case of Dynamic Systems

Science.gov (United States)

Canu, Michaël; de Hosson, Cécile; Duque, Mauricio

2016-01-01

Engineering students in control courses have been observed to lack an understanding of equilibrium and stability, both of which are crucial concepts in this discipline. The introduction of these concepts is generally based on the study of classical examples from Newtonian mechanics supplemented with a control system. Equilibrium and stability are…

Stability Enhancement of Multi machine AC Systems by Synchronverter HVDC control

Directory of Open Access Journals (Sweden)

Raouia Aouini

2016-06-01

Full Text Available This paper investigates the impact of the Synchronverter based HVDC control on power system stability. The study considers multi machine power systems, with realistic parameters. A specific tuning method of the parameters of the regulators is used. The proposed control scheme is based on the sensitivity of the poles of the HVDC neighbor zone to the control parameters, and next, on their placement using residues. The transient stability of the HVDC neighbor zone is a priori taken into account at the design stage. The new tuning method is evaluated in comparison with the standard vector control via simulation tests. Extensive tests are performed using Matlab/Simulink implementation of the IEEE 9 bus/3 machines test system. The results prove the superiority of the proposed control to the classic vector control. The synchronverter control allows to improve not only the local performances of the HVDC link, but also the overall transient stability of the AC zone in which the HVDC is inserted. (where

Escala de Metas de Estudio para Estudiantes Universitarios

Directory of Open Access Journals (Sweden)

María Victoria Pérez Villalobos

2009-01-01

Full Text Available Actualmente disponemos de gran cantidad de trabajos que muestran la implicación de las metas de estudio en la motivación por estudiar y aprender. Este trabajo analiza la motivación académica y, especialmente, la variable "metas de estudio". El principal propósito de esta investigación es conocer las características psicométricas de la adaptación de la Escala de Metas de Estudio a la población universitaria chilena. Los participantes son 542 estudiantes chilenos, de distintas facultades universitarias. Los resultados del análisis factorial y de consistencia interna son aceptables en las tres subescalas. Estos resultados fundamentan el uso de la Escala de Metas de Estudio para evaluar la motivación al estudio de alumnas y alumnos universitarios en Chile (CL.

Application of electrolyzer system to enhance frequency stabilization effect of microturbine in a microgrid system

Energy Technology Data Exchange (ETDEWEB)

Vachirasricirikul, Sitthidet [Department of Electrical Engineering, Faculty of Engineering, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Ngamroo, Issarachai; Kaitwanidvilai, Somyot [Center of Excellence for Innovative Energy Systems, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

2009-09-15

It is well known that the power output of microturbine can be controlled to compensate for load change and alleviate the system frequency fluctuations. Nevertheless, the microturbine may not adequately compensate rapid load change due to its slow dynamic response. Moreover, when the intermittent power generations from wind power and photovoltaic are integrated into the system, they may cause severe frequency fluctuation. In order to study the fast dynamic response, this paper applies electrolyzer system to absorb these power fluctuations and enhance the frequency control effect of microturbine in the microgrid system. The robust coordinated controller of electrolyzer and microturbine for frequency stabilization is designed based on a fixed-structure H{sub {infinity}} loop shaping control. Simulation results exhibit the robustness and stabilizing effects of the proposed coordinated electrolyzer and microturbine controllers against system parameters variation and various operating conditions. (author)

Mean Square Exponential Stability of Stochastic Switched System with Interval Time-Varying Delays

Directory of Open Access Journals (Sweden)

Manlika Rajchakit

2012-01-01

Full Text Available This paper is concerned with mean square exponential stability of switched stochastic system with interval time-varying delays. The time delay is any continuous function belonging to a given interval, but not necessary to be differentiable. By constructing a suitable augmented Lyapunov-Krasovskii functional combined with Leibniz-Newton’s formula, a switching rule for the mean square exponential stability of switched stochastic system with interval time-varying delays and new delay-dependent sufficient conditions for the mean square exponential stability of the switched stochastic system are first established in terms of LMIs. Numerical example is given to show the effectiveness of the obtained result.

Stability Analysis for Multi-Parameter Linear Periodic Systems

DEFF Research Database (Denmark)

Seyranian, A.P.; Solem, Frederik; Pedersen, Pauli

1999-01-01

This paper is devoted to stability analysis of general linear periodic systems depending on real parameters. The Floquet method and perturbation technique are the basis of the development. We start out with the first and higher-order derivatives of the Floquet matrix with respect to problem...

Finite-Time Stability of Large-Scale Systems with Interval Time-Varying Delay in Interconnection

Directory of Open Access Journals (Sweden)

T. La-inchua

2017-01-01

Full Text Available We investigate finite-time stability of a class of nonlinear large-scale systems with interval time-varying delays in interconnection. Time-delay functions are continuous but not necessarily differentiable. Based on Lyapunov stability theory and new integral bounding technique, finite-time stability of large-scale systems with interval time-varying delays in interconnection is derived. The finite-time stability criteria are delays-dependent and are given in terms of linear matrix inequalities which can be solved by various available algorithms. Numerical examples are given to illustrate effectiveness of the proposed method.

Dynamical stability of the holographic system with two competing orders

Energy Technology Data Exchange (ETDEWEB)

Du, Yiqiang [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Lan, Shan-Quan [Department of Physics, Beijing Normal University,Beijing 100875 (China); Tian, Yu [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Science,Beijing 100190 (China); Zhang, Hongbao [Department of Physics, Beijing Normal University,Beijing 100875 (China); Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)

2016-01-04

We investigate the dynamical stability of the holographic system with two order parameters, which exhibits competition and coexistence of condensations. In the linear regime, we have developed the gauge dependent formalism to calculate the quasi-normal modes by gauge fixing, which turns out be considerably convenient. Furthermore, by giving different Gaussian wave packets as perturbations at the initial time, we numerically evolve the full nonlinear system until it arrives at the final equilibrium state. Our results show that the dynamical stability is consistent with the thermodynamical stability. Interestingly, the dynamical evolution, as well as the quasi-normal modes, shows that the relaxation time of this model is generically much longer than the simplest holographic system. We also find that the late time behavior can be well captured by the lowest lying quasi-normal modes except for the non-vanishing order towards the single ordered phase. To our knowledge, this exception is the first counter example to the general belief that the late time behavior towards a final stable state can be captured by the lowest lying quasi-normal modes. In particular, a double relation is found for this exception in certain cases.

Stability of Bifurcating Stationary Solutions of the Artificial Compressible System

Science.gov (United States)

Teramoto, Yuka

2018-02-01

The artificial compressible system gives a compressible approximation of the incompressible Navier-Stokes system. The latter system is obtained from the former one in the zero limit of the artificial Mach number ɛ which is a singular limit. The sets of stationary solutions of both systems coincide with each other. It is known that if a stationary solution of the incompressible system is asymptotically stable and the velocity field of the stationary solution satisfies an energy-type stability criterion, then it is also stable as a solution of the artificial compressible one for sufficiently small ɛ . In general, the range of ɛ shrinks when the spectrum of the linearized operator for the incompressible system approaches to the imaginary axis. This can happen when a stationary bifurcation occurs. It is proved that when a stationary bifurcation from a simple eigenvalue occurs, the range of ɛ can be taken uniformly near the bifurcation point to conclude the stability of the bifurcating solution as a solution of the artificial compressible system.

Bias-Voltage Stabilizer for HVHF Amplifiers in VHF Pulse-Echo Measurement Systems.

Science.gov (United States)

Choi, Hojong; Park, Chulwoo; Kim, Jungsuk; Jung, Hayong

2017-10-23

The impact of high-voltage-high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We propose a bias-voltage stabilizer circuit to maintain stable DC voltages over a wide input range, thus reducing the harmonic-distortion components of the echo signals in VHF pulse-echo measurement systems. To confirm the feasibility of the bias-voltage stabilizer, we measured and compared the deviations in the gain of the HVHF amplifier with and without a bias-voltage stabilizer. Between -13 and 26 dBm, the measured gain deviations of a HVHF amplifier with a bias-voltage stabilizer are less than that of an amplifier without a bias-voltage stabilizer. In order to confirm the feasibility of the bias-voltage stabilizer, we compared the pulse-echo responses of the amplifiers, which are typically used for the evaluation of transducers or electronic components used in pulse-echo measurement systems. From the responses, we observed that the amplitudes of the echo signals of a VHF transducer triggered by the HVHF amplifier with a bias-voltage stabilizer were higher than those of the transducer triggered by the HVHF amplifier alone. The second, third, and fourth harmonic-distortion components of the HVHF amplifier with the bias-voltage stabilizer were also lower than those of the HVHF amplifier alone. Hence, the proposed scheme is a promising method for stabilizing the bias voltage of an HVHF amplifier, and improving the echo-signal quality of VHF transducers.

Characterization and stability studies of emulsion systems containing pumice

Directory of Open Access Journals (Sweden)

Marilene Estanqueiro

2014-04-01

Full Text Available Emulsions are the most common form of skin care products. However, these systems may exhibit some instability. Therefore, when developing emulsions for topical application it is interesting to verify whether they have suitable physical and mechanical characteristics and further assess their stability. The aim of this work was to study the stability of emulsion systems, which varied in the proportion of the emulsifying agent cetearyl alcohol (and sodium lauryl sulfate (and sodium cetearyl sulfate (LSX, the nature of the oily phase (decyl oleate, cyclomethicone or dimethicone and the presence or absence of pumice (5% w/w. While maintaining the samples at room temperature, rheology studies, texture analysis and microscopic observation of formulations with and without pumice were performed. Samples were also submitted to an accelerated stability study by centrifugation and to a thermal stress test. Through the testing, it was found that the amount of emulsifying agent affects the consistency and textural properties such as firmness and adhesiveness. So, formulations containing LSX (5% w/w and decyl oleate or dimethicone as oily phase had a better consistency and remained stable with time, so exhibited the best features to be used for skin care products.

System design document for the plutonium stabilization and packaging system

International Nuclear Information System (INIS)

1996-01-01

The objective of this system is to stabilize and package plutonium metals and oxides of greater than 50% wt, as well as other selected isotopes, in accordance with the requirements for DOE standards for safe storage of these materials for 50 years. This document describes the highest level design information and user characteristics from an operational perspective. It provides guidance for developing procurement and installation specifications, interface requirements, and test plans

System design document for the plutonium stabilization and packaging system

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-05-08

The objective of this system is to stabilize and package plutonium metals and oxides of greater than 50% wt, as well as other selected isotopes, in accordance with the requirements for DOE standards for safe storage of these materials for 50 years. This document describes the highest level design information and user characteristics from an operational perspective. It provides guidance for developing procurement and installation specifications, interface requirements, and test plans.

Stability and periodicity of solutions for delay dynamic systems on time scales

Directory of Open Access Journals (Sweden)

Zhi-Qiang Zhu

2014-04-01

Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.

Passivity Based Stabilization of Non-minimum Phase Nonlinear Systems

Czech Academy of Sciences Publication Activity Database

Travieso-Torres, J.C.; Duarte-Mermoud, M.A.; Zagalak, Petr

2009-01-01

Roč. 45, č. 3 (2009), s. 417-426 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GA102/07/1596 Institutional research plan: CEZ:AV0Z10750506 Keywords : nonlinear systems * stabilisation * passivity * state feedback Subject RIV: BC - Control Systems Theory Impact factor: 0.445, year: 2009 http://library.utia.cas.cz/separaty/2009/AS/zagalak-passivity based stabilization of non-minimum phase nonlinear systems.pdf

Transient Stability Enhancement in Power System Using Static VAR Compensator (SVC

Directory of Open Access Journals (Sweden)

Youssef MOULOUDI

2012-12-01

Full Text Available In this paper, an indirect adaptive fuzzy excitation and static VAR (unit of reactive power, volt-ampere reactive compensator (SVC controller is proposed to enhance transient stability for the power system, which based on input-output linearization technique. A three-bus system, which contains a generator and static VAR compensator (SVC, is considered in this paper, the SVC is located at the midpoint of the transmission lines. Simulation results show that the proposed controller compared with a controller based on tradition linearization technique can enhance the transient stability of the power system under a large sudden fault, which may occur nearly at the generator bus terminal.

Research on Handling Stability of Steering-by-wire System

Directory of Open Access Journals (Sweden)

Yuan Ying

2017-01-01

Full Text Available The main function of steer-by-wire (SBW system are improving steering characteristics, security and stability of the vehicle. In this paper, the variable steering ratio of SBW system is analyzed, and the method of steering ratio based on fuzzy control and neural network are researched. In order to solve the actual working condition, the wheel angle may not reach the expected value, this paper establishes a twodegree-of-freedom (2-DOF vehicle model, and a Matlab/Simulink simulation model, in which a control strategy based on PID controller is put forward to control the front wheel steering angle. Simulation results show that proposed control strategy based on fuzzy neural network can effectively reduce lateral deviation and improve the handling stability and comfortability of the vehicle.

Asymptotic stability results for retarded differential systems | Igobi ...

African Journals Online (AJOL)

... matrices are used in formulating a Lyapunov functional. The introduction of convex set segment of a symmetric matrix is explored to establish boundedness of the first derivative of the formulated functional. The integral-differential equation is utilized in computing the maximum delay interval for the system to attain stability.

Stability of Rotor Systems: A Complex Modelling Approach

DEFF Research Database (Denmark)

Kliem, Wolfhard; Pommer, Christian; Stoustrup, Jakob

1996-01-01

A large class of rotor systems can be modelled by a complex matrix differential equation of secondorder. The angular velocity of the rotor plays the role of a parameter. We apply the Lyapunov matrix equation in a complex setting and prove two new stability results which are compared...

Constructing Hopf bifurcation lines for the stability of nonlinear systems with two time delays

Science.gov (United States)

Nguimdo, Romain Modeste

2018-03-01

Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.

The impact of loss sensitivity on a mobile phone supply chain system stability based on the chaos theory

Science.gov (United States)

Ma, Junhai; Xie, Lei

2018-02-01

This paper, based on the China's communications and the current situation of the mobile phone industry, focuses on the stability of a supply chain system that consists of one supplier and one bounded rational retailer. We explore the influence of the decision makers' loss sensitivity and decision adjustment speed on the stability of the supply chain. It is found that when the retailer is not sensitive to the loss or adjusts decisions cautiously, the system can be stable. The single-retailer model is extended to a multi-retailer one to study the influence of competition on the system stability. The results show that the market share of each retailer does not affect the system stability when it is fixed. The decision of each retailer does not affect that of any other retailer and the system stability. We present two decision adjustment rules (;bounded rationality expectation (BRE); and "adaptive exponential smoothing (AES)") and compare their performances on the system stability, and find that the AES rule does not affect the system stability, while the BRE rule will make the system stability be sensitive to the retailers' loss sensitivity and the decision adjustment speed. We also reveal the unstable system's negative impact on the retailers' decisions and profits, to emphasize the importance to maintain the system stability.

On stability of fixed points and chaos in fractional systems.

Science.gov (United States)

Edelman, Mark

2018-02-01

In this paper, we propose a method to calculate asymptotically period two sinks and define the range of stability of fixed points for a variety of discrete fractional systems of the order 0chaos is impossible in the corresponding continuous fractional systems.

Exponential Stability of Time-Switched Two-Subsystem Nonlinear Systems with Application to Intermittent Control

Directory of Open Access Journals (Sweden)

Huang Tingwen

2009-01-01

Full Text Available This paper studies the exponential stability of a class of periodically time-switched nonlinear systems. Three cases of such systems which are composed, respectively, of a pair of unstable subsystems, of both stable and unstable subsystems, and of a pair of stable systems, are considered. For the first case, the proposed result shows that there exists periodically switching rule guaranteeing the exponential stability of the whole system with (sufficient small switching period if there is a Hurwitz linear convex combination of two uncertain linear systems derived from two subsystems by certain linearization. For the second case, we present two general switching criteria by means of multiple and single Lyapunov function, respectively. We also investigate the stability issue of the third case, and the switching criteria of exponential stability are proposed. The present results for the second case are further applied to the periodically intermittent control. Several numerical examples are also given to show the effectiveness of theoretical results.

Some stability and boundedness criteria for a class of Volterra integro-differential systems

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Jito Vanualailai

2002-01-01

Full Text Available Using Lyapunov and Lyapunov-like functionals, we study the stability and boundedness of the solutions of a system of Volterra integrodifferential equations. Our results, also extending some of the more well-known criteria, give new sufficient conditions for stability of the zero solution of the nonperturbed system, and prove that the same conditions for the perturbed system yield boundedness when the perturbation is $L^2$.

Local bounds preserving stabilization for continuous Galerkin discretization of hyperbolic systems

Science.gov (United States)

Mabuza, Sibusiso; Shadid, John N.; Kuzmin, Dmitri

2018-05-01

The objective of this paper is to present a local bounds preserving stabilized finite element scheme for hyperbolic systems on unstructured meshes based on continuous Galerkin (CG) discretization in space. A CG semi-discrete scheme with low order artificial dissipation that satisfies the local extremum diminishing (LED) condition for systems is used to discretize a system of conservation equations in space. The low order artificial diffusion is based on approximate Riemann solvers for hyperbolic conservation laws. In this case we consider both Rusanov and Roe artificial diffusion operators. In the Rusanov case, two designs are considered, a nodal based diffusion operator and a local projection stabilization operator. The result is a discretization that is LED and has first order convergence behavior. To achieve high resolution, limited antidiffusion is added back to the semi-discrete form where the limiter is constructed from a linearity preserving local projection stabilization operator. The procedure follows the algebraic flux correction procedure usually used in flux corrected transport algorithms. To further deal with phase errors (or terracing) common in FCT type methods, high order background dissipation is added to the antidiffusive correction. The resulting stabilized semi-discrete scheme can be discretized in time using a wide variety of time integrators. Numerical examples involving nonlinear scalar Burgers equation, and several shock hydrodynamics simulations for the Euler system are considered to demonstrate the performance of the method. For time discretization, Crank-Nicolson scheme and backward Euler scheme are utilized.

Linear systems with unstructured multiplicative uncertainty: Modeling and robust stability analysis.

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Radek Matušů

Full Text Available This article deals with continuous-time Linear Time-Invariant (LTI Single-Input Single-Output (SISO systems affected by unstructured multiplicative uncertainty. More specifically, its aim is to present an approach to the construction of uncertain models based on the appropriate selection of a nominal system and a weight function and to apply the fundamentals of robust stability investigation for considered sort of systems. The initial theoretical parts are followed by three extensive illustrative examples in which the first order time-delay, second order and third order plants with parametric uncertainty are modeled as systems with unstructured multiplicative uncertainty and subsequently, the robust stability of selected feedback loops containing constructed models and chosen controllers is analyzed and obtained results are discussed.

Power system stabilizers based on distributed energy resources for damping of inter-area oscillations

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Stefanov Predrag Č.

2014-01-01

Full Text Available This paper deals with inter-area power oscillations damping enhancement by distributed energy resources contained in typical micro grid. Main idea behind this work is to use distributed generation and distributed storage, such as battery energy storage to mimic conventional power system stabilizer, but with regulating active power output, rather than reactive power, as in standard power system stabilizer realization. The analysis of the small signal stability is established for four-machine, two-area system, with inverter based micro grids in each area. Dynamic simulation results are included in this work and they show that proposed controller provides additional damping effect to this test system.

Stability Constrained Efficiency Optimization for Droop Controlled DC-DC Conversion System

DEFF Research Database (Denmark)

Meng, Lexuan; Dragicevic, Tomislav; Guerrero, Josep M.

2013-01-01

implementing tertiary regulation. Moreover, system dynamic is affected when shifting VRs. Therefore, the stability is considered in optimization by constraining the eigenvalues arising from dynamic state space model of the system. Genetic algorithm is used in searching for global efficiency optimum while....... As the efficiency of each converter changes with output power, virtual resistances (VRs) are set as decision variables for adjusting power sharing proportion among converters. It is noteworthy that apart from restoring the voltage deviation, secondary control plays an important role to stabilize dc bus voltage when...

An Optimal Power Flow (OPF) Method with Improved Power System Stability

DEFF Research Database (Denmark)

Su, Chi; Chen, Zhe

2010-01-01

This paper proposes an optimal power flow (OPF) method taking into account small signal stability as additional constraints. Particle swarm optimization (PSO) algorithm is adopted to realize the OPF process. The method is programmed in MATLAB and implemented to a nine-bus test power system which...... has large-scale wind power integration. The results show the ability of the proposed method to find optimal (or near-optimal) operating points in different cases. Based on these results, the analysis of the impacts of wind power integration on the system small signal stability has been conducted....

Finite-time output feedback stabilization of high-order uncertain nonlinear systems

Science.gov (United States)

Jiang, Meng-Meng; Xie, Xue-Jun; Zhang, Kemei

2018-06-01

This paper studies the problem of finite-time output feedback stabilization for a class of high-order nonlinear systems with the unknown output function and control coefficients. Under the weaker assumption that output function is only continuous, by using homogeneous domination method together with adding a power integrator method, introducing a new analysis method, the maximal open sector Ω of output function is given. As long as output function belongs to any closed sector included in Ω, an output feedback controller can be developed to guarantee global finite-time stability of the closed-loop system.

Model based PI power system stabilizer design for damping low frequency oscillations in power systems.

Science.gov (United States)

Salgotra, Aprajita; Pan, Somnath

2018-05-01

This paper explores a two-level control strategy by blending local controller with centralized controller for the low frequency oscillations in a power system. The proposed control scheme provides stabilization of local modes using a local controller and minimizes the effect of inter-connection of sub-systems performance through a centralized control. For designing the local controllers in the form of proportional-integral power system stabilizer (PI-PSS), a simple and straight forward frequency domain direct synthesis method is considered that works on use of a suitable reference model which is based on the desired requirements. Several examples both on one machine infinite bus and multi-machine systems taken from the literature are illustrated to show the efficacy of the proposed PI-PSS. The effective damping of the systems is found to be increased remarkably which is reflected in the time-responses; even unstable operation has been stabilized with improved damping after applying the proposed controller. The proposed controllers give remarkable improvement in damping the oscillations in all the illustrations considered here and as for example, the value of damping factor has been increased from 0.0217 to 0.666 in Example 1. The simulation results obtained by the proposed control strategy are favourably compared with some controllers prevalent in the literature. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Wind Turbine and Wind Power Plant Modelling Aspects for Power System Stability Studies

DEFF Research Database (Denmark)

Altin, Müfit; Hansen, Anca Daniela; Göksu, Ömer

2014-01-01

Large amount of wind power installations introduce modeling challenges for power system operators at both the planning and operational stages of power systems. Depending on the scope of the study, the modeling details of the wind turbine or the wind power plant are required to be different. A wind...... turbine model which is developed for the short-term voltage stability studies can be inaccurate and sufficient for the frequency stability studies. Accordingly, a complete and detailed wind power plant model for every kind of study is not feasible in terms of the computational time and also...... and wind power plants are reviewed for power system stability studies. Important remarks of the models are presented by means of simulations to emphasize the impact of these modelling details on the power system....

Oscillatory Stability and Eigenvalue Sensitivity Analysis of A DFIG Wind Turbine System

DEFF Research Database (Denmark)

Yang, Lihui; Xu, Zhao; Østergaard, Jacob

2011-01-01

This paper focuses on modeling and oscillatory stability analysis of a wind turbine with doubly fed induction generator (DFIG). A detailed mathematical model of DFIG wind turbine with vector-control loops is developed, based on which the loci of the system Jacobian's eigenvalues have been analyzed......, showing that, without appropriate controller tuning a Hopf bifurcation can occur in such a system due to various factors, such as wind speed. Subsequently, eigenvalue sensitivity with respect to machine and control parameters is performed to assess their impacts on system stability. Moreover, the Hopf...

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

DEFF Research Database (Denmark)

Weckesser, Johannes Tilman Gabriel; Jóhannsson, Hjörtur; Glavic, Mevludin

2017-01-01

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent...... method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases...... the simulation can be terminated after a few hundred milliseconds of simulated system response. The method's outcome is an assessment of the system's stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus...

Analysis of the Gyroscopic Stabilization of a System of Rigid Bodies

DEFF Research Database (Denmark)

Kliem, Wolfhard; Kliem, Wolfhard

1996-01-01

We study the gyroscopic of a three-body system. A new method offinding stability regions, based on mechanism and criteria for gyroscopicstabilization, is presented. Of particular interest in this connection isthe theory of interaction of eigenvalues. This leads to a complete 3-dimensionalanalysis......, which shows the regions of stability, divergence, and flutter ofa simple model of a rotating spaceship....

Power System Transient Stability Improvement Using Demand Side Management in Competitive Electricity Markets

DEFF Research Database (Denmark)

Hu, Weihao; Wang, Chunqi; Chen, Zhe

2012-01-01

Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift some of their loads from high price periods to the low price periods in order to save their energy costs. The optimal load response to an electricity price...... for demand side management generates different load profiles and may provide an opportunity to improve the transient stability of power systems with high wind power penetrations. In this paper, the idea of the power system transient stability improvement by using optimal load response to the electricity...... price is proposed. A 102-bus power system which represents a simplified model of the western Danish power system is chosen as the study case. Simulation results show that the optimal load response to electricity prices is an effective measure to improve the power system transient stability with high...

Casos de Estudio de Distribuciones de Probabilidad para Turismo

OpenAIRE

Fernández Morales, Antonio

2016-01-01

Este trabajo propone diversos casos de estudio para el estudio de las distribuciones de probabilidad aplicadas a la investigación y la práctica profesional en el ámbito del turismo. Se afronta el estudio de distribuciones de probabilidad, tanto de variables aleatorias discretas como continuas.

The pointer basis and the feedback stabilization of quantum systems

International Nuclear Information System (INIS)

Li, L; Chia, A; Wiseman, H M

2014-01-01

The dynamics for an open quantum system can be ‘unravelled’ in infinitely many ways, depending on how the environment is monitored, yielding different sorts of conditioned states, evolving stochastically. In the case of ideal monitoring these states are pure, and the set of states for a given monitoring forms a basis (which is overcomplete in general) for the system. It has been argued elsewhere (Atkins et al 2005 Europhys. Lett. 69 163) that the ‘pointer basis’ as introduced by Zurek et al (1993 Phys. Rev. Lett. 70 1187), should be identified with the unravelling-induced basis which decoheres most slowly. Here we show the applicability of this concept of pointer basis to the problem of state stabilization for quantum systems. In particular we prove that for linear Gaussian quantum systems, if the feedback control is assumed to be strong compared to the decoherence of the pointer basis, then the system can be stabilized in one of the pointer basis states with a fidelity close to one (the infidelity varies inversely with the control strength). Moreover, if the aim of the feedback is to maximize the fidelity of the unconditioned system state with a pure state that is one of its conditioned states, then the optimal unravelling for stabilizing the system in this way is that which induces the pointer basis for the conditioned states. We illustrate these results with a model system: quantum Brownian motion. We show that even if the feedback control strength is comparable to the decoherence, the optimal unravelling still induces a basis very close to the pointer basis. However if the feedback control is weak compared to the decoherence, this is not the case. (paper)

ℋ∞ constant gain state feedback stabilization of stochastic hybrid systems with Wiener process

Directory of Open Access Journals (Sweden)

E. K. Boukas

2004-01-01

Full Text Available This paper considers the stabilization problem of the class of continuous-time linear stochastic hybrid systems with Wiener process. The ℋ∞ state feedback stabilization problem is treated. A state feedback controller with constant gain that does not require access to the system mode is designed. LMI-based conditions are developed to design the state feedback controller with constant gain that stochastically stabilizes the studied class of systems and, at the same time, achieve the disturbance rejection of a desired level. The minimum disturbance rejection is also determined. Numerical examples are given to show the usefulness of the proposed results.

Robust Stability Analysis of the Space Launch System Control Design: A Singular Value Approach

Science.gov (United States)

Pei, Jing; Newsome, Jerry R.

2015-01-01

Classical stability analysis consists of breaking the feedback loops one at a time and determining separately how much gain or phase variations would destabilize the stable nominal feedback system. For typical launch vehicle control design, classical control techniques are generally employed. In addition to stability margins, frequency domain Monte Carlo methods are used to evaluate the robustness of the design. However, such techniques were developed for Single-Input-Single-Output (SISO) systems and do not take into consideration the off-diagonal terms in the transfer function matrix of Multi-Input-Multi-Output (MIMO) systems. Robust stability analysis techniques such as H(sub infinity) and mu are applicable to MIMO systems but have not been adopted as standard practices within the launch vehicle controls community. This paper took advantage of a simple singular-value-based MIMO stability margin evaluation method based on work done by Mukhopadhyay and Newsom and applied it to the SLS high-fidelity dynamics model. The method computes a simultaneous multi-loop gain and phase margin that could be related back to classical margins. The results presented in this paper suggest that for the SLS system, traditional SISO stability margins are similar to the MIMO margins. This additional level of verification provides confidence in the robustness of the control design.

GOLD NETTING TO STRENGTHEN FINANCIAL SYSTEM STABILITY

Directory of Open Access Journals (Sweden)

Ahamed Kameel Mydin Meera

2017-08-01

Full Text Available Economic and financial crises seem to occur with increased frequency. Indeed now most countries, including several advanced economies like the US, Europe and Japan, are in serious economic recession. Employment and business opportunities have been much dampened. Inflation seems to be soaring globally and nations are witnessing widening gaps in income and wealth distribution. Many of these advanced economies are also facing shrinking population sizes that translate into aging problems and labor shortages. On top of those, there are environmental issues, including global warming. All these, in turn, have caused regional and global political conflicts and turmoil. The Arab Spring and the sovereign debt problems faced by some European countries like Greece are examples of this. Sustainability of economics and environment is thus of paramount concern of today. This paper considers those problems and suggests Interest-free Gold-based Electronic Netting System (IGENS as an effective way of injecting liquidity into the economy, practically free, that can spur business and employment while bringing about structural stability, inflation checked with both economic and environmental sustainability. Netting or muqassah is a transaction allowed in shari’ah and is practiced worldwide in different forms. Examples include the highly successful WIR Bank of Switzerland, various Local Exchange Trading Schemes (LETS and Bilateral and Multilateral Payment Arrangements between central banks.   Keywords:  Global crisis, Payment system, Gold, Netting, Muqassah, Liquidity, Sustainability, Financial system stability JEL Classification: E40, E42, E51

Estudio de la legislación ambiental en licencias de dragados de puertos en Brasil y España. Estudio de caso

OpenAIRE

VIÑES BERNARDO, MARGARITA

2011-01-01

Este TFC consistirá en la realización de un estudio de la legislación ambiental existente en relación al dragado de puertos en Brasil y en España, en el análisis de los procesos de licenciamiento y de la metodología de la monitorización del dragado aplicada en un estudio de caso. Viñes Bernardo, M. (2011). Estudio de la legislación ambiental en licencias de dragados de puertos en Brasil y España. Estudio de caso. http://hdl.handle.net/10251/10344. Archivo delegado

Development of real-time voltage stability monitoring tool for power system transmission network using Synchrophasor data

Science.gov (United States)

Pulok, Md Kamrul Hasan

Intelligent and effective monitoring of power system stability in control centers is one of the key issues in smart grid technology to prevent unwanted power system blackouts. Voltage stability analysis is one of the most important requirements for control center operation in smart grid era. With the advent of Phasor Measurement Unit (PMU) or Synchrophasor technology, real time monitoring of voltage stability of power system is now a reality. This work utilizes real-time PMU data to derive a voltage stability index to monitor the voltage stability related contingency situation in power systems. The developed tool uses PMU data to calculate voltage stability index that indicates relative closeness of the instability by producing numerical indices. The IEEE 39 bus, New England power system was modeled and run on a Real-time Digital Simulator that stream PMU data over the Internet using IEEE C37.118 protocol. A Phasor data concentrator (PDC) is setup that receives streaming PMU data and stores them in Microsoft SQL database server. Then the developed voltage stability monitoring (VSM) tool retrieves phasor measurement data from SQL server, performs real-time state estimation of the whole network, calculate voltage stability index, perform real-time ranking of most vulnerable transmission lines, and finally shows all the results in a graphical user interface. All these actions are done in near real-time. Control centers can easily monitor the systems condition by using this tool and can take precautionary actions if needed.

Estudios Experimentales 1 Parte: El Ensayo Clínico

OpenAIRE

Manterola, Carlos; Otzen, Tamara

2015-01-01

Los estudios experimentales, se caracterizan por la valoración del efecto de una o más intervenciones, habitualmente de forma comparativa con otra intervención, o un placebo; y el carácter prospectivo, de la recolección de los datos y el seguimiento de los grupos en estudio. Bajo la denominación de estudios experimentales, existe una diversidad de diseños, desde los ensayos clínicos (EC) y sus variantes, hasta los estudios cuasi-experimentales y los experientos naturales. El objetivo de este ...

Improvement of Transient Stability of Power System by System Damping Series Resistor (SDSR)

OpenAIRE

上里, 勝実; 千住, 智信; 当銘, 秀之; 高原, 景滋; Uezato, Katsumi; Senjyu, Tomonobu; Toume, Hideyuki; Takahara, Keiji

1990-01-01

The system damping resistor is one of the method for improving the transient stability of power systems. The main circuit is the simple construction so that is low cost and is few abnormal surge, and is superior in ability of economy, reliability and maintenance. Conventionally, most of all system damping resistors have adopted the paralleled resistor, whereas the series resistor is used little.In this paper, we investigate the characteristics of the series resistor by comparing with the para...

Regional modeling approach for analyzing harmonic stability in radial power electronics based power system

DEFF Research Database (Denmark)

Yoon, Changwoo; Bai, Haofeng; Wang, Xiongfei

2015-01-01

Stability analysis of distributed power generation system becomes complex when there are many numbers of grid inverters in the system. In order to analyze system stability, the overall network impedance will be lumped and needs to be analyzed one by one. However, using a unified bulky transfer-fu...... and then it is expanded for generalizing its concept to an overall radial structured network....

Static and dynamic stability of pneumatic vibration isolators and systems of isolators

Science.gov (United States)

Ryaboy, Vyacheslav M.

2014-01-01

Pneumatic vibration isolation is the most widespread effective method for creating vibration-free environments that are vital for precise experiments and manufacturing operations in optoelectronics, life sciences, microelectronics, nanotechnology and other areas. The modeling and design principles of a dual-chamber pneumatic vibration isolator, basically established a few decades ago, continue to attract attention of researchers. On the other hand, behavior of systems of such isolators was never explained in the literature in sufficient detail. This paper covers a range of questions essential for understanding the mechanics of pneumatic isolation systems from both design and application perspectives. The theory and a model of a single standalone isolator are presented in concise form necessary for subsequent analysis. Then the dynamics of a system of isolators supporting a payload is considered with main attention directed to two aspects of their behavior: first, the static stability of payloads with high positions of the center of gravity; second, dynamic stability of the feedback system formed by mechanical leveling valves. The direct method of calculating the maximum stable position of the center of gravity is presented and illustrated by three-dimensional stability domains; analytic formulas are given that delineate these domains. A numerical method for feedback stability analysis of self-leveling valve systems is given, and the results are compared with the analytical estimates for a single isolator. The relation between the static and dynamic phenomena is discussed.

Energy principles for linear dissipative systems with application to resistive MHD stability

International Nuclear Information System (INIS)

Pletzer, A.

1997-04-01

A formalism for the construction of energy principles for dissipative systems is presented. It is shown that dissipative systems satisfy a conservation law for the bilinear Hamiltonian provided the Lagrangian is time invariant. The energy on the other hand, differs from the Hamiltonian by being quadratic and by having a negative definite time derivative (positive power dissipation). The energy is a Lyapunov functional whose definiteness yields necessary and sufficient stability criteria. The stability problem of resistive magnetohydrodynamic (MHD) is addressed: the energy principle for ideal MHD is generalized and the stability criterion by Tasso is shown to be necessary in addition to sufficient for real growth rates. An energy principle is found for the inner layer equations that yields the resistive stability criterion D R <0 in the incompressible limit, whereas the tearing mode criterion Δ'<0 is shown to result from the conservation law of the bilinear concomitant in the resistive layer. (author) 1 fig., 25 refs

An offset tone based gain stabilization technique for mixed-signal RF measurement systems

Energy Technology Data Exchange (ETDEWEB)

Joshi, Gopal, E-mail: gjos@barc.gov.in [BARC, Mumbai 400085 (India); Motiwala, Paresh D.; Randale, G.D.; Singh, Pitamber [BARC, Mumbai 400085 (India); Agarwal, Vivek; Kumar, Girish [IIT Bombay, Powai, Mumbai 400076 (India)

2015-09-21

This paper describes a gain stabilization technique for a RF signal measurement system. A sinusoidal signal of known amplitude, phase and close enough in frequency is added to the main, to be measured RF signal at the input of the analog section. The system stabilizes this offset tone in the digital domain, as it is sampled at the output of the analog section. This process generates a correction factor needed to stabilize the magnitude of the gain of the analog section for the main RF signal. With the help of a simple calibration procedure, the absolute amplitude of the main RF signal can be measured. The technique is especially suited for a system that processes signals around a single frequency, employs direct signal conversion into the digital domain, and processes subsequent steps in an FPGA. The inherent parallel signal processing in an FPGA-based implementation allows a real time stabilization of the gain. The effectiveness of the technique is derived from the fact, that the gain stabilization stamped to the main RF signal measurement branch requires only a few components in the system to be inherently stable. A test setup, along with experimental results is presented from the field of RF instrumentation for particle accelerators. Due to the availability of a phase synchronized RF reference signal in these systems, the measured phase difference between the main RF and the RF reference is also stabilized using this technique. A scheme of the signal processing is presented, where a moving average filter has been used to filter out not only the unwanted frequencies, but also to separate the main RF signal from the offset tone signal. This is achieved by a suitable choice of sampling and offset tone frequencies. The presented signal processing scheme is suitable to a variety of RF measurement applications.

Study on the stability of waterpower-speed control system for hydropower station with air cushion surge chamber

International Nuclear Information System (INIS)

Guo, W C; Yang, J D; Chen, J P; Teng, Y

2014-01-01

According to the fact that the effects of penstock, unit and governor on stability of water level fluctuation for hydropower station with air cushion surge chamber are neglected in previous researches, in this paper, Thoma assumption is broken through, the complete mathematical model of waterpower-speed control system for hydropower station with air cushion surge chamber is established, and the comprehensive transfer function and linear homogeneous differential equation that characterize the dynamic characteristics of system are derived. The stability domain that characterizes the good or bad of stability quantitatively is drawn by using the stability conditions. The effects of the fluid inertia in water diversion system, the air cushion surge chamber parameters, hydraulic turbine characteristics, generator characteristics, and regulation modes of governor on the stability of waterpower-speed control system are analyzed through stability domain. The main conclusions are as follows: The fluid inertia in water diversion system and hydraulic turbine characteristics have unfavorable effects on the system while generator characteristics have favorable effect. The stability keeps getting better with the increase of chamber height and basal area and the decrease of air pressure and air polytropic exponent. The stability of power regulation mode is obviously better than that of frequency regulation mode

A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

Science.gov (United States)

Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

2015-10-01

Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

Dynamic stability of a vertically excited non-linear continuous system

Czech Academy of Sciences Publication Activity Database

Náprstek, Jiří; Fischer, Cyril

2015-01-01

Roč. 155, July (2015), s. 106-114 ISSN 0045-7949 R&D Projects: GA ČR(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : non-linear systems * auto-parametric systems * semi-trivial solution * dynamic stability * system recovery * post- critical response Subject RIV: JM - Building Engineering Impact factor: 2.425, year: 2015 http://www.sciencedirect.com/science/article/pii/S0045794915000024

QFT Framework for Robust Tuning of Power System Stabilizers

DEFF Research Database (Denmark)

Alavi, Seyyed Mohammad Mahdi; Izadi-Zamanabadi, Roozbeh

2005-01-01

This paper discusses the use of conventional quantitative feedback design for Power System Stabilizer (PSS). An appropriate control structure of the PSS that is directly applicable to PSS, is described. Two desired performances are also proposed in order to achieve an overall improvement in damping...... and robustness. The efficiency of the proposed method is demonstrated on Single Machine Infinite Bus (SMIB) power system with level of uncertainty....

Stability Analysis of Nonlinear Time–Delayed Systems with Application to Biological Models

Directory of Open Access Journals (Sweden)

Kruthika H.A.

2017-03-01

Full Text Available In this paper, we analyse the local stability of a gene-regulatory network and immunotherapy for cancer modelled as nonlinear time-delay systems. A numerically generated kernel, using the sum-of-squares decomposition of multivariate polynomials, is used in the construction of an appropriate Lyapunov–Krasovskii functional for stability analysis of the networks around an equilibrium point. This analysis translates to verifying equivalent LMI conditions. A delay-independent asymptotic stability of a second-order model of a gene regulatory network, taking into consideration multiple commensurate delays, is established. In the case of cancer immunotherapy, a predator–prey type model is adopted to describe the dynamics with cancer cells and immune cells contributing to the predator–prey population, respectively. A delay-dependent asymptotic stability of the cancer-free equilibrium point is proved. Apart from the system and control point of view, in the case of gene-regulatory networks such stability analysis of dynamics aids mimicking gene networks synthetically using integrated circuits like neurochips learnt from biological neural networks, and in the case of cancer immunotherapy it helps determine the long-term outcome of therapy and thus aids oncologists in deciding upon the right approach.

Partial stabilization and control of distributed parameter systems with elastic elements

CERN Document Server

Zuyev, Alexander L

2015-01-01

 This monograph provides a rigorous treatment of problems related to partial asymptotic stability and controllability for models of flexible structures described by coupled nonlinear ordinary and partial differential equations or equations in abstract spaces. The text is self-contained, beginning with some basic results from the theory of continuous semigroups of operators in Banach spaces. The problem of partial asymptotic stability with respect to a continuous functional is then considered for a class of abstract multivalued systems on a metric space. Next, the results of this study are applied to the study of a rotating body with elastic attachments. Professor Zuyev demonstrates that the equilibrium cannot be made strongly asymptotically stable in the general case, motivating consideration of the problem of partial stabilization with respect to the functional that represents “averaged” oscillations. The book’s focus moves on to spillover analysis for infinite-dimensional systems with finite-dimensio...

A real-time BWR [boiling water reactor] stability measurement system

International Nuclear Information System (INIS)

March-Leuba, J.; King, W.T.

1987-01-01

This paper describes the characteristics of a portable, real-time system used for nonperturbational measurements of stability in boiling water reactors. The algorithm used in this system estimates the closed-loop asymptotic decay ratio using only the naturally occurring neutron noise and it is based on the univariate autoregressive methodology

Stability of dynamical systems on the role of monotonic and non-monotonic Lyapunov functions

CERN Document Server

Michel, Anthony N; Liu, Derong

2015-01-01

The second edition of this textbook provides a single source for the analysis of system models represented by continuous-time and discrete-time, finite-dimensional and infinite-dimensional, and continuous and discontinuous dynamical systems.  For these system models, it presents results which comprise the classical Lyapunov stability theory involving monotonic Lyapunov functions, as well as corresponding contemporary stability results involving non-monotonicLyapunov functions.Specific examples from several diverse areas are given to demonstrate the applicability of the developed theory to many important classes of systems, including digital control systems, nonlinear regulator systems, pulse-width-modulated feedback control systems, and artificial neural networks.   The authors cover the following four general topics:   -          Representation and modeling of dynamical systems of the types described above -          Presentation of Lyapunov and Lagrange stability theory for dynamical sy...

Stability and Control of Large-Scale Dynamical Systems A Vector Dissipative Systems Approach

CERN Document Server

Haddad, Wassim M

2011-01-01

Modern complex large-scale dynamical systems exist in virtually every aspect of science and engineering, and are associated with a wide variety of physical, technological, environmental, and social phenomena, including aerospace, power, communications, and network systems, to name just a few. This book develops a general stability analysis and control design framework for nonlinear large-scale interconnected dynamical systems, and presents the most complete treatment on vector Lyapunov function methods, vector dissipativity theory, and decentralized control architectures. Large-scale dynami

Viscosity of the oil-in-water Pickering emulsion stabilized by surfactant-polymer and nanoparticle-surfactant-polymer system

Science.gov (United States)

Sharma, Tushar; Kumar, G. Suresh; Chon, Bo Hyun; Sangwai, Jitendra S.

2014-11-01

Information on the viscosity of Pickering emulsion is required for their successful application in upstream oil and gas industry to understand their stability at extreme environment. In this work, a novel formulation of oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide) system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry, 2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditions using a controlled-strain rheometer. The nanoparticle (SiO2 and clay) concentration is varied from 1.0 to 5.0 wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shift in this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yield stress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperature has an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In case of nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantly constant for varying pressure and temperature conditions. The viscosity data for both o/w emulsion systems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the study indicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improved and stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymer system indicating their successful application for HPHT environment in upstream oil and gas industry.

Stability Criterion of Linear Stochastic Systems Subject to Mixed H2/Passivity Performance

Directory of Open Access Journals (Sweden)

Cheung-Chieh Ku

2015-01-01

Full Text Available The H2 control scheme and passivity theory are applied to investigate the stability criterion of continuous-time linear stochastic system subject to mixed performance. Based on the stochastic differential equation, the stochastic behaviors can be described as multiplicative noise terms. For the considered system, the H2 control scheme is applied to deal with the problem on minimizing output energy. And the asymptotical stability of the system can be guaranteed under desired initial conditions. Besides, the passivity theory is employed to constrain the effect of external disturbance on the system. Moreover, the Itô formula and Lyapunov function are used to derive the sufficient conditions which are converted into linear matrix inequality (LMI form for applying convex optimization algorithm. Via solving the sufficient conditions, the state feedback controller can be established such that the asymptotical stability and mixed performance of the system are achieved in the mean square. Finally, the synchronous generator system is used to verify the effectiveness and applicability of the proposed design method.

An Effective Distributed Model for Power System Transient Stability Analysis

Directory of Open Access Journals (Sweden)

MUTHU, B. M.

2011-08-01

Full Text Available The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models.

Computation On dP Type power System Stabilizer Using Fuzzy Logic

International Nuclear Information System (INIS)

Iskandar, M.A.; Irwan, R.; Husdi; Riza; Mardhana, E.; Triputranto, A.

1997-01-01

Power system stabilizers (PSS) are widely applied in power generators to damp power oscillation caused by certain disturbances in order to increase the power supply capacity. PSS design is often suffered from the difficulty on setting periodically its parameters, which are gain and compensators, in order to have an optimal damping characteristic. This paper proposes a methode to determine parameters of dP type PSS by implementing fuzzy logic rules in a computer program,to obtain the appropriate characteristics of synchronous torque and damping torque. PSS with the calculated parameters is investigated on a simulation using a non-linear electric power system of a thermal generator connected to infinite bus system model. Simulation results show that great improvement in damping characteristic and enhancement of stability margin of electric power system are obtained by using the proposed PSS

Virtual velocity loop based on MEMS accelerometers for optical stabilization control system

Science.gov (United States)

Ren, Wei; Deng, Chao; Mao, Yao; Ren, Ge

2017-08-01

In the optical stabilization control system (OSCS) control system based on a charge-coupled device (CCD), stabilization performance of the line-of-sight is severely limited by the mechanical resonance and the low sampling rate of the CCD. An approach to improve the stabilization performance of the OSCS control system with load restriction based on three loops, including an acceleration loop, a virtual velocity loop, and a position loop, by using MEMS accelerometers and a CCD is proposed. The velocity signal is obtained by accelerators instead of gyro sensors. Its advantages are low power, low cost, small size, and wide measuring range. A detailed analysis is provided to show how to design the virtual velocity loop and correct virtual velocity loop drift. Experimental results show that the proposed multiloop feedback control method with virtual velocity loop in which the disturbance suppression performance is better than that of the dual loop control with only an acceleration loop and a position loop at low frequency.

On stability of fixed points and chaos in fractional systems

Science.gov (United States)

Edelman, Mark

2018-02-01

In this paper, we propose a method to calculate asymptotically period two sinks and define the range of stability of fixed points for a variety of discrete fractional systems of the order 0 logistic maps. Based on our analysis, we make a conjecture that chaos is impossible in the corresponding continuous fractional systems.

Estudio de estabilidad de tabletas de propiltiouracilo 50 mg

Directory of Open Access Journals (Sweden)

María Olga Valdés Bendoyro

Full Text Available Se desarrolló el estudio de estabilidad de las tabletas de propiltiouracilo 50 mg y se determinó su fecha de vencimiento. Este estudio se realizó por los métodos de vida de estante y de estabilidad acelerada mediante cromatografía líquida de alta eficiencia, validados en el Centro de Investigación y Desarrollo de Medicamentos. El estudio de vida de estante se desarrolló por un periodo de 24 meses a temperatura ambiente; mientras que el estudio de estabilidad acelerada se efectuó sometiendo el producto a la influencia de la luz, la humedad y la temperatura; se realizó el análisis durante 3 meses, para los 2 primeros y durante 6 meses para el estudio de la temperatura. La formulación de propiltiouracilo tabletas 50 mg cumplió con las especificaciones de calidad descritas en la farmacopea. Los resultados del estudio de estabilidad por vida de estante después de transcurridos los 24 meses indicaron que el producto mantenía los parámetros que determinan su calidad durante ese tiempo, y en los estudios acelerados no se observó degradación significativa del producto. Se estableció 2 años como fecha de vencimiento en las condiciones señaladas.

Preliminary Results on Asymptotic Stabilization of Hamiltonian Systems with Nonholonomic Constraints

NARCIS (Netherlands)

Khennouf, H.; Canudas de Wit, C.; Schaft, A.J. van der

1995-01-01

This paper presents some preliminary results on asymptotic stabilization of nonholonomic mechanical systems using the Hamiltonian formulation proposed previously. Our work seeks to establish a general formulation for designing time-varying controllers for some mechanical system described in the

un estudio comparativo

Directory of Open Access Journals (Sweden)

Federico Varona

2007-01-01

Full Text Available La comunicación efectiva es uno de los mayores retos que tienen hoy las organizaciones y empresas tanto a nivel nacional como internacional (global. Este artículo presenta los resultados de la investigación realizada por un equipo internacional de investigadores interesados en descubrir y comparar las conductas comunicativas o estilos de comunicación de los empleados finlandeses y mexicanos cuando interactúan con sus superiores. Para ello presentamos: primero, un breve marco teórico del estudio; segundo, la metodología; tercero, los resultados del análisis estadístico comparativo entre los empleados de Finlandia y México; cuarto, las conclusiones generales y su explicación cultural; y quinto, las implicaciones teóricas y prácticas de este estudio con respecto a las competencias comunicativas necesarias para la comunicación efectiva entre empleados y superiores tanto en organizaciones nacionales como internacionales (globales.

STABILITY OF LINEAR MULTIAGENT SCALAR SYSTEMS AND ITS DEPENDENCE ON CONNECTIVITY GRAPH

Directory of Open Access Journals (Sweden)

S. I. Tomashevich

2014-03-01

Full Text Available Multiagent systems are now finding increasingly wide applications in various engineering fields such as energy, transportation, robotics, aviation and others. There are two main aspects to be focused on when organizing multiagent systems: the dynamics of the agents themselves and the ways of their interaction. This interaction is determined by the structure of information connections between agents. Thus, there are several key points of multiagent systems study: the dynamics of individual agents and shape of the information graph. Formation dynamics, in general, is determined by a set of properties of agents and connectivity graph. The paper deals with the relationship between dynamics of agents and Laplace matrix, which is used to set the graph connections. The present research is based on the results given in the known paper by A. Fax and R. Murray (IEEE Trans. AC, 2004. An illustrative example is given, and the application problem of studying the formation dynamics consisting of the group of quadrocopters is presented. Information exchange between agents is determined in the paper by means of the conventional set of graphs. The paper presents an interpretation of the stability conditions and the method of system performance improvement based on these conditions. Motion of quadrocopters group along the flight height is used as an example for methodology application. The simulation results demonstrate the basic dependencies between the information graph shape (and, consequently, the eigenvalues of the Laplacian, which describes this graph and formation stability. Simulation and consideration of Nyquist diagram connection with the key points give an indication of the system stability and take steps to change the control laws. Necessary conditions for the formation stability are obtained on the basis of this research method. Research result makes it possible to create local control laws for agents to ensure the stability of motion in the selected

Robust Stabilization of Fractional-Order Systems with Interval Uncertainties via Fractional-Order Controllers

Directory of Open Access Journals (Sweden)

Mohammadtaghi Hamidi Beheshti

2010-01-01

Full Text Available We propose a fractional-order controller to stabilize unstable fractional-order open-loop systems with interval uncertainty whereas one does not need to change the poles of the closed-loop system in the proposed method. For this, we will use the robust stability theory of Fractional-Order Linear Time Invariant (FO-LTI systems. To determine the control parameters, one needs only a little knowledge about the plant and therefore, the proposed controller is a suitable choice in the control of interval nonlinear systems and especially in fractional-order chaotic systems. Finally numerical simulations are presented to show the effectiveness of the proposed controller.

Robust Stabilization of Fractional-Order Systems with Interval Uncertainties via Fractional-Order Controllers

Directory of Open Access Journals (Sweden)

Sayyad Delshad Saleh

2010-01-01

Full Text Available Abstract We propose a fractional-order controller to stabilize unstable fractional-order open-loop systems with interval uncertainty whereas one does not need to change the poles of the closed-loop system in the proposed method. For this, we will use the robust stability theory of Fractional-Order Linear Time Invariant (FO-LTI systems. To determine the control parameters, one needs only a little knowledge about the plant and therefore, the proposed controller is a suitable choice in the control of interval nonlinear systems and especially in fractional-order chaotic systems. Finally numerical simulations are presented to show the effectiveness of the proposed controller.

A study of a steering system algorithm for pleasure boats based on stability analysis of a human-machine system model

International Nuclear Information System (INIS)

Ikeda, Fujio; Toyama, Shigehiro; Ishiduki, Souta; Seta, Hiroaki

2016-01-01

Maritime accidents of small ships continue to increase in number. One of the major factors is poor manoeuvrability of the Manual Hydraulic Steering Mechanism (MHSM) in common use. The manoeuvrability can be improved by using the Electronic Control Steering Mechanism (ECSM). This paper conducts stability analyses of a pleasure boat controlled by human models in view of path following on a target course, in order to establish design guidelines for the ECSM. First, to analyse the stability region, the research derives the linear approximated model in a planar global coordinate system. Then, several human models are assumed to develop closed-loop human-machine controlled systems. These human models include basic proportional, derivative, integral and time-delay actions. The stability analysis simulations for those human-machine systems are carried out. The results show that the stability region tends to spread as a ship's velocity increases in the case of the basic proportional human model. The derivative action and time-delay action of human models are effective in spreading the stability region in their respective ranges of frontal gazing points. (paper)

A study of a steering system algorithm for pleasure boats based on stability analysis of a human-machine system model

Science.gov (United States)

Ikeda, Fujio; Toyama, Shigehiro; Ishiduki, Souta; Seta, Hiroaki

2016-09-01

Maritime accidents of small ships continue to increase in number. One of the major factors is poor manoeuvrability of the Manual Hydraulic Steering Mechanism (MHSM) in common use. The manoeuvrability can be improved by using the Electronic Control Steering Mechanism (ECSM). This paper conducts stability analyses of a pleasure boat controlled by human models in view of path following on a target course, in order to establish design guidelines for the ECSM. First, to analyse the stability region, the research derives the linear approximated model in a planar global coordinate system. Then, several human models are assumed to develop closed-loop human-machine controlled systems. These human models include basic proportional, derivative, integral and time-delay actions. The stability analysis simulations for those human-machine systems are carried out. The results show that the stability region tends to spread as a ship's velocity increases in the case of the basic proportional human model. The derivative action and time-delay action of human models are effective in spreading the stability region in their respective ranges of frontal gazing points.

Bundle Adjustment-Based Stability Analysis Method with a Case Study of a Dual Fluoroscopy Imaging System

Science.gov (United States)

Al-Durgham, K.; Lichti, D. D.; Detchev, I.; Kuntze, G.; Ronsky, J. L.

2018-05-01

A fundamental task in photogrammetry is the temporal stability analysis of a camera/imaging-system's calibration parameters. This is essential to validate the repeatability of the parameters' estimation, to detect any behavioural changes in the camera/imaging system and to ensure precise photogrammetric products. Many stability analysis methods exist in the photogrammetric literature; each one has different methodological bases, and advantages and disadvantages. This paper presents a simple and rigorous stability analysis method that can be straightforwardly implemented for a single camera or an imaging system with multiple cameras. The basic collinearity model is used to capture differences between two calibration datasets, and to establish the stability analysis methodology. Geometric simulation is used as a tool to derive image and object space scenarios. Experiments were performed on real calibration datasets from a dual fluoroscopy (DF; X-ray-based) imaging system. The calibration data consisted of hundreds of images and thousands of image observations from six temporal points over a two-day period for a precise evaluation of the DF system stability. The stability of the DF system - for a single camera analysis - was found to be within a range of 0.01 to 0.66 mm in terms of 3D coordinates root-mean-square-error (RMSE), and 0.07 to 0.19 mm for dual cameras analysis. It is to the authors' best knowledge that this work is the first to address the topic of DF stability analysis.

Criteria for stability of linear dynamical systems with multiple delays ...

African Journals Online (AJOL)

In this study we considered a linear Dynamical system with multiple delays and find suitable conditions on the systems parameters such that for a given initial function, we can define a mapping in a carefully chosen complete metric space on which the mapping has a unique fixed point. An asymptotic stability theory for the ...

Asymptotic Stabilization of Continuous-Time Linear Systems with Input and State Quantizations

Directory of Open Access Journals (Sweden)

Sung Wook Yun

2014-01-01

Full Text Available This paper discusses the asymptotic stabilization problem of linear systems with input and state quantizations. In order to achieve asymptotic stabilization of such systems, we propose a state-feedback controller comprising two control parts: the main part is used to determine the fundamental characteristics of the system associated with the cost, and the additional part is employed to eliminate the effects of input and state quanizations. In particular, in order to implement the additional part, we introduce a quantizer with a region-decision making process (RDMP for a certain linear switching surface. The simulation results show the effectiveness of the proposed controller.

Estudio comparativo entre SIG propietario y SIG libre

OpenAIRE

Mesa Díaz, Juan Ramón

2008-01-01

Estudio comparativo entre SIG propietario y SIG libre, focalizado en los casos particulares de Geomedia Pro (SIG Propietario) y gvSIG (SIG Libre). En el estudio se procede a determinar cuáles son los aspectos destacables de un SIG, para poder evaluarlos, posteriormente, en los dos SIG objeto del estudio y obtener una ponderación definitoria de cada SIG. A continuación, algunos de los aspectos evaluados en cada SIG: interoperabilidad, conexión a bases de datos espaciales, aspectos económ...

Local and global stability for Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks

Science.gov (United States)

Faria, Teresa; Oliveira, José J.

This paper addresses the local and global stability of n-dimensional Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks. Necessary and sufficient conditions for local stability independent of the choice of the delay functions are given, by imposing a weak nondelayed diagonal dominance which cancels the delayed competition effect. The global asymptotic stability of positive equilibria is established under conditions slightly stronger than the ones required for the linear stability. For the case of monotone interactions, however, sharper conditions are presented. This paper generalizes known results for discrete delays to systems with distributed delays. Several applications illustrate the results.

Solutions Stability of Initial Boundary Problem, Modeling of Dynamics of Some Discrete Continuum Mechanical System

Directory of Open Access Journals (Sweden)

D. A. Eliseev

2015-01-01

Full Text Available The solution stability of an initial boundary problem for a linear hybrid system of differential equations, which models the rotation of a rigid body with two elastic rods located in the same plane is studied in the paper. To an axis passing through the mass center of the rigid body perpendicularly to the rods location plane is applied the stabilizing moment proportional to the angle of the system rotation, derivative of the angle, integral of the angle. The external moment provides a feedback. A method of studying the behavior of solutions of the initial boundary problem is proposed. This method allows to exclude from the hybrid system of differential equations partial differential equations, which describe the dynamics of distributed elements of a mechanical system. It allows us to build one equation for an angle of the system rotation. Its characteristic equation defines the stability of solutions of all the system. In the space of feedback-coefficients the areas that provide the asymptotic stability of solutions of the initial boundary problem are built up.

Lifetime of Bentonites study: hydrothermal stability of saponites; Estudio de longevidad en bentonitas: estabilidad hidrotermal de saponitas

Energy Technology Data Exchange (ETDEWEB)

Leguey, S; Cuevas, J; Garralon, A [Universidad Autonoma de Madrid, Facultad de Ciencias, Departamento de Quimica Agricola, Geologia y Geoquimica, Madrid (Spain)

1996-10-01

The report studies the lifetime of bentonite and the hydrothermal stability of saponites. The testing comprised determination of physical and chemical properties of clays, the stability of the mineral porosity, lifetime and the wall of clay.

Performance Comparison of Adaptive Estimation Techniques for Power System Small-Signal Stability Assessment

Directory of Open Access Journals (Sweden)

E. A. Feilat

2010-12-01

Full Text Available This paper demonstrates the assessment of the small-signal stability of a single-machine infinite- bus power system under widely varying loading conditions using the concept of synchronizing and damping torques coefficients. The coefficients are calculated from the time responses of the rotor angle, speed, and torque of the synchronous generator. Three adaptive computation algorithms including Kalman filtering, Adaline, and recursive least squares have been compared to estimate the synchronizing and damping torque coefficients. The steady-state performance of the three adaptive techniques is compared with the conventional static least squares technique by conducting computer simulations at different loading conditions. The algorithms are compared to each other in terms of speed of convergence and accuracy. The recursive least squares estimation offers several advantages including significant reduction in computing time and computational complexity. The tendency of an unsupplemented static exciter to degrade the system damping for medium and heavy loading is verified. Consequently, a power system stabilizer whose parameters are adjusted to compensate for variations in the system loading is designed using phase compensation method. The effectiveness of the stabilizer in enhancing the dynamic stability over wide range of operating conditions is verified through the calculation of the synchronizing and damping torque coefficients using recursive least square technique.

Nonlinear modeling and stability analysis of hydro-turbine governing system with sloping ceiling tailrace tunnel under load disturbance

International Nuclear Information System (INIS)

Guo, Wencheng; Yang, Jiandong; Wang, Mingjiang; Lai, Xu

2015-01-01

Highlights: • Novel nonlinear mathematical model of hydro-turbine governing system is proposed. • Hopf bifurcation analysis on the governing system is conducted. • Stability of the system under load disturbance is studied. • Influence of four factors on stability is analyzed. • Optimization methods of improving system stability are put forward. - Abstract: In order to overcome the problem of nonlinear dynamics of hydro-turbine governing system with sloping ceiling tailrace tunnel, which is caused by the interface movement of the free surface-pressurized flow in the tailrace tunnel, and the difficulty of analyzing the stability of system, this paper uses the Hopf bifurcation theory to study the stability of hydro-turbine governing system of hydropower station with sloping ceiling tailrace tunnel. Firstly, a novel and rational nonlinear mathematical model of the hydro-turbine governing system is proposed. This model contains the dynamic equation of pipeline system which can accurately describe the motion characteristics of the interface of free surface-pressurized flow in sloping ceiling tailrace tunnel. According to the nonlinear mathematical model, the existence and direction of Hopf bifurcation of the nonlinear dynamic system are analyzed. Furthermore, the algebraic criterion of the occurrence of Hopf bifurcation is derived. Then the stability domain and bifurcation diagram of hydro-turbine governing system are drawn by the algebraic criterion, and the characteristics of stability under different state parameters are investigated. Finally, the influence of step load value, ceiling slope angle and section form of tailrace tunnel and water depth at the interface in tailrace tunnel on stability are analyzed based on stable domain. The results indicate that: The Hopf bifurcation of hydro-turbine governing system with sloping ceiling tailrace tunnel is supercritical. The phase space trajectories of characteristic variables stabilize at the equilibrium points

Power System Stabilizer Design Based on a Particle Swarm Optimization Multiobjective Function Implemented Under Graphical Interface

Directory of Open Access Journals (Sweden)

Ghouraf Djamel Eddine

2016-05-01

Full Text Available Power system stability considered a necessary condition for normal functioning of an electrical network. The role of regulation and control systems is to ensure that stability by determining the essential elements that influence it. This paper proposes a Particle Swarm Optimization (PSO based multiobjective function to tuning optimal parameters of Power System Stabilizer (PSS; this later is used as auxiliary to generator excitation system in order to damp electro mechanicals oscillations of the rotor and consequently improve Power system stability. The computer simulation results obtained by developed graphical user interface (GUI have proved the efficiency of PSS optimized by a Particle Swarm Optimization, in comparison with a conventional PSS, showing stable   system   responses   almost   insensitive   to   large parameter variations.Our present study was performed using a GUI realized under MATLAB in our work.

Role of Glutaraldehyde in Imparting Stability to Immobilized β-Galactosidase Systems

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Rukhsana Satar

2018-01-01

Full Text Available ABSTRACT This review article highlights the role of glutaraldehyde as a matrix activator/stabilizer in imparting higher operational and thermal stability to β-galactosidase (βG for biotechnological applications. Glutaraldehyde has been used extensively as a crosslinking agent as well as for functionalization of matrices to immobilize β-galactosidase. Immobilized β-galactosidase systems (IβGS obtained as a result of glutaraldehyde treatment has been employed to hydrolyze whey and milk lactose in batch reactors, continuous packed-bed and fluidized bed reactors under various operational conditions. Moreover, these IβGS have also been utilized for the production of galactooligosaccharides in food, dairy and fermentation industries. It was observed that glutaraldehyde provided remarkable stability to immobilize βG against various physical/chemical denaturants, thus enhancing thermal/operational stability and rendering it more suitable for repeated utilization in industrial scale operations.

Automotive mechatronics automotive networking, driving stability systems, electronics

CERN Document Server

2015-01-01

As the complexity of automotive vehicles increases this book presents operational and practical issues of automotive mechatronics. It is a comprehensive introduction to controlled automotive systems and provides detailed information of sensors for travel, angle, engine speed, vehicle speed, acceleration, pressure, temperature, flow, gas concentration etc. The measurement principles of the different sensor groups are explained and examples to show the measurement principles applied in different types. Contents Basics of mechatronics.- Architecture.- Electronic control unit.- Software development.- Basic principles of networking.- Automotive networking.- Bus systems.- Automotive sensors.- Sensor measuring principles.- Sensor types.- Electric actuators.- Electrohydraulic actuators.- Electronic transmission control.- Electronic transmission control unit.- Modules for transmission control.- Antilock braking system.- Traction control system.- Electronic stability program.- Automatic brake functions.- Hydraulic modu...

ESTUDIOS (INTERCULTURALES EN CLAVE DE-COLONIAL

Directory of Open Access Journals (Sweden)

Catherine Walsh

2010-01-01

Full Text Available Los «estudios culturales» en América Latina forman parte de una política de nombrar inscrita en legados y cartografiados frecuentemente como totalidad, ocultando o dejando pasar por alto las diferencias a su interior. Este articula examina desde dónde nacen los estudios culturales en América Latina en general y en la Universidad Andina Simón Bolívar en Quito en particular, con qué política de nombramiento, qué proyecto(s y qué bases y perspectivas de conocimiento. Considera qué implica concebir y construir los estudios culturales como proyecto político-intelectual, inter-cultural, inter-epistémico y de orientación de-colonial y los desafíos y obstáculos al respecto, incluyendo dentro de la problemática misma de la «uni»-versidad.

Stability of periodic steady-state solutions to a non-isentropic Euler-Poisson system

Science.gov (United States)

Liu, Cunming; Peng, Yue-Jun

2017-06-01

We study the stability of periodic smooth solutions near non-constant steady-states for a non-isentropic Euler-Poisson system without temperature damping term. The system arises in the theory of semiconductors for which the doping profile is a given smooth function. In this stability problem, there are no special restrictions on the size of the doping profile, but only on the size of the perturbation. We prove that small perturbations of periodic steady-states are exponentially stable for large time. For this purpose, we introduce new variables and choose a non-diagonal symmetrizer of the full Euler equations to recover dissipation estimates. This also allows to make the proof of the stability result very simple and concise.

DESIGN OF ROBUST NAVIGATION AND STABILIZATION LOOPS OF PRECISION ATTITUDE AND HEADING REFERENCE SYSTEM

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Olha Sushchenko

2017-11-01

Full Text Available Purpose: The paper focuses on problems of design of robust precision attitude and heading reference systems, which can be applied in navigation of marine vehicles. The main goal is to create the optimization procedures for design of navigation and stabilization loops of the multimode gimballed system. The optimization procedure of the navigation loop design is based on the parametric robust H2/H∞-optimization. The optimization procedure of the stabilization loop design is based on the robust structural H∞-synthesis. Methods: To solve the given problem the methods of the robust control system theory and optimization methods are used. Results: The kinematical scheme of the precision gimballed attitude and heading reference system is represented. The parametrical optimization algorithm taking into consideration features of the researched system is given. Method of the mixed sensitivity relative to the researched system design is analyzed. Coefficients of the control laws of navigation loops are obtained based on optimization procedure providing compromise between accuracy and robustness. The robust controller of the stabilization loop was developed based on robust structural synthesis using method of the mixed sensitivity. Simulation of navigation and stabilization processes is carried out. Conclusions: The represented results prove efficiency of the proposed procedures, which can be useful for design of precision navigation systems of the moving vehicles.

de estudios observacionales

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Erik von Elm

2008-01-01

un documento de explicación y elaboración al que puede accederse libremente en los sitios web de PLoS Medicine, Annals of Internal Medicine y Epidemiology. Esperamos que la declaración STROBE contribuya a mejorar la calidad de la publicación de los estudios observacionales.

Harmonics and voltage stability analysis in power systems including

Indian Academy of Sciences (India)

In this study, non-sinusoidal quantities and voltage stability, both known as power quality criteria, are examined together in detail. The widespread use of power electronics elements cause the existence of significant non-sinusoidal quantities in the system. These non-sinusoidal quantities can create serious harmonic ...

An alternative soil nailing system for slope stabilization: Akarpiles

Science.gov (United States)

Lim, Chun-Lan; Chan, Chee-Ming

2017-11-01

This research proposes an innovative solution for slope stabilization with less environmental footprint: AKARPILES. In Malaysia, landslide has become common civil and environmental problems that cause impacts to the economy, safety and environment. Therefore, effective slope stabilization method helps to improve the safety of public and protect the environment. This study focused on stabilizing surfacial slope failure. The idea of AKARPILES was generated from the tree roots system in slope stabilization. After the piles are installed in the slope and intercepting the slip plane, grout was pumped in and discharged through holes on the piles. The grout then filled the pores in the soil with random flow within the slip zone. SKW mixture was used to simulate the soil slope. There were two designs being proposed in this study and the prototypes were produced by a 3D printer. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. A series of tests were conducted on the single-pile-reinforced slope under vertical slope crest loading condition considering different slope gradients and nail designs. Parameters such as ultimate load, failure time and failure strain were recorded and compared. As comparison with the unreinforced slope, both designs of AKARPILES showed better but different performances in the model tests.

Stabilization of pH in solid-matrix hydroponic systems

Science.gov (United States)

Frick, J.; Mitchell, C. A.

1993-01-01

2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mM) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite : 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g m-2 day-1) were about double that of the control (8.2 g m-2 day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g m-2 day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mM MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.

Handbook of electrical power system dynamics modeling, stability, and control

CERN Document Server

Eremia, Mircea

2013-01-01

Complete guidance for understanding electrical power system dynamics and blackouts This handbook offers a comprehensive and up-to-date treatment of power system dynamics. Addressing the full range of topics, from the fundamentals to the latest technologies in modeling, stability, and control, Handbook of Electrical Power System Dynamics provides engineers with hands-on guidance for understanding the phenomena leading to blackouts so they can design the most appropriate solutions for a cost-effective and reliable operation. Focusing on system dynamics, the book details

Evaluation of constraint stabilization procedures for multibody dynamical systems

Science.gov (United States)

Park, K. C.; Chiou, J. C.

1987-01-01

Comparative numerical studies of four constraint treatment techniques for the simulation of general multibody dynamic systems are presented, and results are presented for the example of a classical crank mechanism and for a simplified version of the seven-link manipulator deployment problem. The staggered stabilization technique (Park, 1986) is found to yield improved accuracy and robustness over Baumgarte's (1972) technique, the singular decomposition technique (Walton and Steeves, 1969), and the penalty technique (Lotstedt, 1979). Furthermore, the staggered stabilization technique offers software modularity, and the only data each solution module needs to exchange with the other is a set of vectors plus a common module to generate the gradient matrix of the constraints, B.

A summary of impacts of wind power integration on power system small-signal stability

Science.gov (United States)

Yan, Lei; Wang, Kewen

2017-05-01

Wind power has been increasingly integrated into power systems over the last few decades because of the global energy crisis and the pressure on environmental protection, and the stability of the system connected with wind power is becoming more prominent. This paper summaries the research status, achievements as well as deficiencies of the research on the impact of wind power integration on power system small-signal stability. In the end, the further research needed are discussed.

Impact Analysis of Roller System Stability for Four-High Mill Horizontal Vibration

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Xiao-bin Fan

2016-01-01

Full Text Available In order to study the hot Compact Strip Production (CSP, four-high mill vibration characteristics, and vibration suppression method, the roller system structure stability was analyzed and calculated at first in the paper. And then, the mill stand gap was measured at field and its influence on roll transverse vibration was analyzed. The drum gear coupling effect on the roller system stability and the automatic balance conditions of the coupling transmission torque were studied; the influence of axial force caused by the roller cross on the system stability was analyzed. Finally, the roller transverse friction chatter vibration mechanics model was established; the simulation analysis was carried out with eliminating mill house-bearing clearance and adding floating support for coupling, respectively. And the characteristics of the roller “jump vibration” were studied. We applied copper gaskets to eliminate or reduce mill house-bearing clearance for suppressing the rolling mill vibration on the spot; the test results show that the roller transverse vibration was suppressed after eliminating clearance.

Application of stabilization techniques in the dynamic analysis of multibody systems

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Hajžman M.

2007-11-01

Full Text Available This paper is intended to the discussion of possible methods for the solution of the motion equations of constrained multibody systems. They can be formulated in the form of differential-algebraic equations and their numerical solution brings the problems of constraint violation and numerical stability. Therefore special methods were proposed to handle these problems. Various approaches for the numerical solution of equations are briefly reviewed and the application of the Baumgarte’s stabilization method on testing examples is shown. The paper was motivated by the effort to find the suitable solution methods for the equations of motion in the form of differentialalgebraic equations using the MATLAB standard computational system.

ANÁLISIS DEL CONTRATO DE LECTURA DE DOS PUBLICACIONES PERIÓDICAS DE CIENCIAS SOCIALES DE ARGENTINA: ESTUDIOS. REVISTA DEL CENTRO DE ESTUDIOS AVANZADOS (UNC Y ESTUDIOS SOCIALES (UNL

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Florencia María Páez

2012-01-01

Full Text Available Pretendemos con este trabajo efectuar un análisis del contrato de lectura de dos publicaciones periódicas de Argentina que se inscriben en el campo de estudios de las ciencias sociales. Partimos de las ideas de Eliseo Verón, esbozadas en “Cuando leer es hacer: la enunciación en el discurso de la prensa gráfica” (1984, y realizamos una apropiación de las categorías del autor teniendo en cuenta las particularidades propias de las revistas científicas y el modo de funcionamiento del subcampo de publicaciones de ciencias sociales del país, en íntima relación con los capitales en juego en el campo científico en general. Hemos escogido uno de los últimos números de cada una de las revistas Estudios del Centro de Estudios Avanzados de la UNC, y Estudios Sociales, de la Universidad Nacional del Litoral. Los criterios que fueron atendidos al momento de la elección de estas revistas apuntaron a la factibilidad de efectuar una comparación entre los contratos de lectura de ambas, según la propuesta de Verón en torno a este tipo de análisis. Este estudio nos permite profundizar nuestra comprensión del funcionamiento de la comunicación científica gráfica, puntualmente posibilita conocer las estrategias que las publicaciones despliegan para captar a los académicos (potenciales lectores y autores en las revistas y para convencer de la calidad científica de su trabajo editorial a los encargados de elaborar índices y catálogos de publicación.

Razonamiento covariacional en el estudio de funciones cuadráticas

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Jhony Alexander Villa-Ochoa

2012-10-01

Full Text Available En este artículo se usa el marco conceptual de Carlson et al. (2003 para discutir los resultados de un estudio de caso, el cual describe la forma como un estudiante razona covariacionalmente al enfrentarse a situaciones de variación asociadas a funciones cuadráticas. El estudio se ideó para desarrollar una línea convergente de indagación (Yin, 2009, la cual se centró en las descripciones que el estudiante realizaba a medida que abordaba las situaciones diseñadas para el estudio; dichas descripciones fueron trianguladas con las producciones escritas y los elementos teóricos. Desde las acciones que el estudiante evidenció, se pudo observar que el proceso de razonamiento covariacional no es un proceso lineal pero sí recursivo. Así mismo, este estudio de caso pone en evidencia el hecho de que existen estudiantes que pueden aproximarse a una interpretación variacional de las concavidades de una gráfica, sin que ello exija un estudio previo del cálculo diferencial. Del estudio se desprenden algunas implicaciones tanto para el marco conceptual abordado en este estudio como para el diseño de situaciones orientadas al aula de clase.

Stability properties of cold blanket systems for current driven modes

International Nuclear Information System (INIS)

Ohlsson, D.

1977-12-01

The stability problem of the boundary regions of cold blanket systems with induced currents parallel to the lines of force is formulated. Particular interest is focused on two types of modes: first electrostatic modes driven by the combined effects of a transverse resistivity gradient due to a spatially non-uniform electron temperature and a longitudinal current, second electromagnetic kink like modes driven by the torque arising from a transverse current density gradient and magnetic field perturbations. It is found that the combination of various dissipative and neutral gas effects introduces strong stabilizing effects within specific parameter ranges. For particular steady-state models investigated it is shown that these effects become of importance in laboratory plasmas at relatively high densities, low temperatures and moderate magnetic field strengths. Stability diagrams based on specific steady-state cold plasma blanket models will be presented

Optimized Extreme Learning Machine for Power System Transient Stability Prediction Using Synchrophasors

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Yanjun Zhang

2015-01-01

Full Text Available A new optimized extreme learning machine- (ELM- based method for power system transient stability prediction (TSP using synchrophasors is presented in this paper. First, the input features symbolizing the transient stability of power systems are extracted from synchronized measurements. Then, an ELM classifier is employed to build the TSP model. And finally, the optimal parameters of the model are optimized by using the improved particle swarm optimization (IPSO algorithm. The novelty of the proposal is in the fact that it improves the prediction performance of the ELM-based TSP model by using IPSO to optimize the parameters of the model with synchrophasors. And finally, based on the test results on both IEEE 39-bus system and a large-scale real power system, the correctness and validity of the presented approach are verified.

14 CFR 23.672 - Stability augmentation and automatic and power-operated systems.

Science.gov (United States)

2010-01-01

... power-operated systems. 23.672 Section 23.672 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... and power-operated systems. If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show compliance with the flight characteristics requirements of this part...

Magnet/cryocooler integration for thermal stability in conduction-cooled systems

Science.gov (United States)

Chang, H.-M.; Kwon, K. B.

2002-05-01

The stability conditions that take into accounts the size of superconducting magnets and the refrigeration capacity of cryocoolers are investigated for the conduction-cooled systems without liquid cryogens. The worst scenario in the superconducting systems is that the heat generation in the resistive state exceeds the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown by an analytical solution that in the continuously resistive state, the temperature may increase indefinitely or a stable steady state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is presented and the design of the stable magnet/cryocooler interface is demonstrated.

Effects of nuclear electromagnetic pulse (EMP) on synchronous stability of the electric power system

International Nuclear Information System (INIS)

Manweiler, R.W.

1975-11-01

The effects of a nuclear electromagnetic pulse (EMP) on the synchronous stability of the electric power transmission and distribution systems are evaluated. The various modes of coupling of EMP to the power system are briefly discussed, with particular emphasis on those perturbations affecting the synchronous stability of the transmission system. A brief review of the fundamental concepts of the stability problem is given, with a discussion of the general characteristics of transient analysis. A model is developed to represent single sets as well as repetitive sets of multiple faults on the distribution systems, as might be produced by EMP. The results of many numerical stability calculations are presented to illustrate the transmission system's response from different types of perturbations. The important parameters of both multiple and repetitive faults are studied, including the dependence of the response on the size of the perturbed area, the fault density, and the effective impedance between the fault location and the transmission system. Both major load reduction and the effect of the opening of tie lines at the time of perturbation are also studied. We conclude that there is a high probability that EMP can induce perturbations on the distribution networks causing a large portion of the transmission network in the perturbed area to lose synchronism. The result would be an immediate and massive power failure

[Study on relationship between emotional stability in flight and nerve system excitability].

Science.gov (United States)

Liu, Fang; Huang, Wei-fen; Jing, Xiao-lu; Zhang, Ping

2003-06-01

To study the related factors of emotional stability in flight. Based on the operable definition of emotional stability in flight and the related literature review, 63 experienced pilots and flight coaches were investigated and the other-rating questionnaire of emotional stability in flight was established. To test the senior nerve system, Uchida Kraeplin (UK) test was administrated on 153 19-21 years old male student pilots of the second grade in the department of flight technique in China Civil Aviation College, who were selected through 13 h flight, 35 h solo flight, and acted as the standardization group. In the end, the correlation was explored between the testing results and their emotional behavioral characteristics in flight. Significant positive correlation was found between emotional feature indexes of emotional stability in flight and excitability in UK test. The excitability in UK test are good predictors for emotional stability in flight.

El creciente campo de los Estudios Sensoriales

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David Howes

2014-09-01

Full Text Available Este ensayo presenta una breve descripción acerca del giro sensorial en la investigación contemporánea, y propone algunas perspectivas de trabajo para futuras investigaciones. Esta labor no pretende ser exhaustiva y, más bien, busca indicar las principales tendencias en este campo. El ensayo, en su primera parte, ofrece una mirada general sobre la aparición y el desarrollo de la historia y la antropología de los sentidos. En la segunda parte, la atención se concentra en cómo el campo de los estudios sensoriales puede ser, de otro lado, conceptualizado como compuesto de cultura visual, cultura auditiva (o estudios del sonido, cultura del olfato, cultura del gusto y cultura del tacto. Se ofrece una explicación acerca de la génesis de estas divisiones. Posteriormente, se presenta una visión general de algunas cuestiones claves en los estudios sensoriales, como la pregunta por el número de los sentidos y la relación entre orden sensorial y orden social. El ensayo concluye con ocho proposiciones para los estudios sensoriales.

El creciente campo de los Estudios Sensoriales

Directory of Open Access Journals (Sweden)

David Howes

2014-08-01

Full Text Available Este ensayo presenta una breve descripción acerca del giro sensorial en la investigación contemporánea, y propone algunas perspectivas de trabajo para futurasinvestigaciones. Esta labor no pretende ser exhaustiva y, más bien, busca indicar las principales tendencias en este campo. El ensayo, en su primera parte, ofrece una mirada general sobre la aparición y el desarrollo de la historia y la antropología de los sentidos. En la segunda parte, la atención se concentra en cómo el campo de los estudios sensoriales puede ser, de otro lado, conceptualizado como compuesto de cultura visual, cultura auditiva (o estudios del sonido, cultura del olfato, cultura del gusto y cultura del tacto. Se ofrece una explicación acerca de la génesis de estas divisiones. Posteriormente,se presenta una visión general de algunas cuestiones claves en los estudios sensoriales, como la pregunta por el número de los sentidos y la relación entre orden sensorial y orden social. El ensayo concluye con ocho proposiciones para los estudios sensoriales.

Investigations on hydrodynamic stability of two phase flow in a low pressure natural circulation system

Energy Technology Data Exchange (ETDEWEB)

Shaorong, Wu; Dazhong, Wang; Meisheng, Yao; Jinhai, Bo; Yunxian, Tong; Shengyao, Jiang; Bing, Han [Institute of Nuclear Energy and Technology, Tsingua Univ., Beijing (China)

1997-09-01

Appropriately scaled ``Loop Stability`` tests and ``Channel Stability`` tests were performed with single heated channel system and two parallel channel system separately at the Institute of Nuclear Energy Technology (INET) of the Tsinghua University in China. A broad range of several operational parameters such as heating power, system pressure, test inlet subcooling and resistance coefficient were investigated. It was found that under certain geometric conditions and operating parameters a self-sustaining, low frequency, even amplitude mass flow oscillation may be excited at very low steam qualities and subcooling conditions. Stability maps under different conditions have been provided to assist the design of the NHR. (author). 6 refs, 15 figs.

Robust Coordinated Design of PSS and TCSC using PSO Technique for Power System Stability Enhancement

Directory of Open Access Journals (Sweden)

S. Panda

2007-06-01

Full Text Available Power system stability improvement by coordinated design of a Power System Stabilizer (PSS and a Thyristor Controlled Series Compensator (TCSC controller is addressed in this paper. Particle Swarm Optimization (PSO technique is employed for optimization of the parameterconstrained nonlinear optimization problem implemented in a simulation environment. The proposed controllers are tested on a weakly connected power system. The non-linear simulation results are presented for wide range of loading conditions with various fault disturbances and fault clearing sequences as well as for various small disturbances. The eigenvalue analysis and simulation results show the effectiveness and robustness of proposed controllers to improve the stability performance of power system by efficient damping of low frequency oscillations under various disturbances.

Stability and stabilization of nonlinear systems and Takagi-Sugeno's fuzzy models

Directory of Open Access Journals (Sweden)

Blanco Yann

2001-01-01

Full Text Available This paper outlines a methodology to study the stability of Takagi-Sugeno's (TS fuzzy models. The stability analysis of the TS model is performed using a quadratic Liapunov candidate function. This paper proposes a relaxation of Tanaka's stability condition: unlike related works, the equations to be solved are not Liapunov equations for each rule matrix, but a convex combination of them. The coefficients of this sums depend on the membership functions. This method is applied to the design of continuous controllers for the TS model. Three different control structures are investigated, among which the Parallel Distributed Compensation (PDC. An application to the inverted pendulum is proposed here.

PWL approximation of nonlinear dynamical systems, part I: structural stability

International Nuclear Information System (INIS)

Storace, M; De Feo, O

2005-01-01

This paper and its companion address the problem of the approximation/identification of nonlinear dynamical systems depending on parameters, with a view to their circuit implementation. The proposed method is based on a piecewise-linear approximation technique. In particular, this paper describes the approximation method and applies it to some particularly significant dynamical systems (topological normal forms). The structural stability of the PWL approximations of such systems is investigated through a bifurcation analysis (via continuation methods)

AC system stabilization via phase shift transformer with thyristor commutation

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Jose Carlos de; Guimaraes, Geraldo Caixeta; Moraes, Adelio Jose [Uberlandia Univ., MG (Brazil); Abreu, Jose Policarpo G. de [Escola Federal de Engenharia de Itajuba, MG (Brazil); Oliveira, Edimar Jose de [Juiz de Fora Univ., MG (Brazil)

1994-12-31

This article aims to present initially the constructive and operative forms of a phase-shift autotransformer which provides both magnitude and phase angle change through thyristor commutation, including a technic to reduce the number of thyristors. Following, it is proposed a control system to make such equipment an efficient AC system stabilizing tool. It is presented some simulation results to show the operation of this transformer in an electrical system. (author) 3 refs., 11 figs., 3 tabs.

Nonlinear Synergetic Governor Controllers for Steam Turbine Generators to Enhance Power System Stability

Directory of Open Access Journals (Sweden)

Xingbao Ju

2017-07-01

Full Text Available This paper proposes a decentralized nonlinear synergetic governor controller (NSGC for turbine generators to enhance power system stability by using synergetic control theory and the feedback linearization technique. The precise feedback linearization model of a turbine-generator with a steam valve control is obtained, at first, by using a feedback linearization technique. Then based on this model, a manifold is defined as a linear combination of the deviation of the rotor angle, speed deviation, and speed derivative. The control law of the proposed NSGC is deduced and the stability condition of the whole closed-loop system is subsequently analyzed. According to the requirement of the primary frequency regulation, an additional proportional integral (PI controller is designed to dynamically track the steady-state value of the rotor angle. Case studies are undertaken based on a single-machine infinite-bus system and the New England system, respectively. Simulation results show that the proposed NSGC can suppress the power oscillations and improve transient stability more effectively in comparison with the conventional proportional-integral-derivative (PID governor controller. Moreover, the proposed NSGC is robust to the variations of the system operating conditions.

Intelligent Control of UPFC for Enhancing Transient Stability on Multi-Machine Power Systems

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Hassan Barati

2010-01-01

Full Text Available One of the benefit of FACTS devices is increase of stability in power systems with control active and reactive power at during the fault in power system. Although, the power system stabilizers (PSSs have been one of the most common controls used to damp out oscillations, this device may not produce enough damping especially to inter-area mode and therefore, there is an increasing interest in using FACTS devices to aid in damping of these oscillations. In This paper, UPFC is used for damping oscillations and to enhance the transient stability performance of power systems. The controller parameters are designed using an efficient version of the Takagi-Sugeno fuzzy control scheme. The function based Takagi-Sugeno-Kang (TSK fuzzy controller uses. For optimization parameters of fuzzy PI controller, the GA, PSO and HGAPSO algorithms are used. The computer simulation results, the effect of UPFC with conventional PI controller, fuzzy PI controller and intelligent controllers (GA, PSO and HGAPSO for damping the local-mode and inter-area mode of under large and small disturbances in the four-machine two-area power system evaluated and compared.

Pseudodifferential Perturbations and Stabilization of Distributed Parameter Systems: Dirichlet Feedback Control Problems

DEFF Research Database (Denmark)

Pedersen, Michael

1991-01-01

The stabilization problems for parabolic and hyperbolic partial differential equations with Dirichlet boundary condition are considered. The systems are stabilized by a boundary feedback in(1) The operator equation,(2) The boundary condition,(3) Both the operator equation and the boundary condition...... turns out to be a shortcut to some of the stabilization results of Lasiecka and Triggiani in [J. Differential Equations, 47 (1983), pp. 245-272], [SIAM J. Control Optim., 21(1983), pp. 766-802], and [Appl. Math. Optim., 8(1981), pp. 1-37], and it illuminates to some extent how a change of boundary...

Stability Enhancement of a Power System Containing High-Penetration Intermittent Renewable Generation

Directory of Open Access Journals (Sweden)

Jorge Morel

2015-06-01

Full Text Available This paper considers the transient stability enhancement of a power system containing large amounts of solar and wind generation in Japan. Following the Fukushima Daiichi nuclear disaster there has been an increasing awareness on the importance of a distributed architecture, based mainly on renewable generation, for the Japanese power system. Also, the targets of CO2 emissions can now be approached without heavily depending on nuclear generation. Large amounts of renewable generation leads to a reduction in the total inertia of the system because renewable generators are connected to the grid by power converters, and transient stability becomes a significant issue. Simulation results show that sodium-sulfur batteries can keep the system in operation and stable after strong transient disturbances, especially for an isolated system. The results also show how the reduction of the inertia in the system can be mitigated by exploiting the kinetic energy of wind turbines.

Stability and Bifurcation in Magnetic Flux Feedback Maglev Control System

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Wen-Qing Zhang

2013-01-01

Full Text Available Nonlinear properties of magnetic flux feedback control system have been investigated mainly in this paper. We analyzed the influence of magnetic flux feedback control system on control property by time delay and interfering signal of acceleration. First of all, we have established maglev nonlinear model based on magnetic flux feedback and then discussed hopf bifurcation’s condition caused by the acceleration’s time delay. The critical value of delayed time is obtained. It is proved that the period solution exists in maglev control system and the stable condition has been got. We obtained the characteristic values by employing center manifold reduction theory and normal form method, which represent separately the direction of hopf bifurcation, the stability of the period solution, and the period of the period motion. Subsequently, we discussed the influence maglev system on stability of by acceleration’s interfering signal and obtained the stable domain of interfering signal. Some experiments have been done on CMS04 maglev vehicle of National University of Defense Technology (NUDT in Tangshan city. The results of experiments demonstrate that viewpoints of this paper are correct and scientific. When time lag reaches the critical value, maglev system will produce a supercritical hopf bifurcation which may cause unstable period motion.

Generalized direct Lyapunov method for the analysis of stability and attraction in general time systems

International Nuclear Information System (INIS)

Druzhinina, O V; Shestakov, A A

2002-01-01

A generalized direct Lyapunov method is put forward for the study of stability and attraction in general time systems of the following types: the classical dynamical system in the sense of Birkhoff, the general system in the sense of Zubov, the general system in the sense of Seibert, the general system with delay, and the general 'input-output' system. For such systems, with the help of generalized Lyapunov functions with respect to two filters, two quasifilters, or two filter bases, necessary and sufficient conditions for stability and attraction are obtained under minimal assumptions about the mathematical structure of the general system

Stabilization of Electromagnetic Suspension System Behavior by Genetic Algorithm

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Abbas Najar Khoda Bakhsh

2012-07-01

Full Text Available Electromagnetic suspension system with a nonlinear and unstable behavior, is used in maglev trains. In this paper a linear mathematical model of system is achieved and the state feedback method is used to improve the system stability. The control coefficients are tuned by two different methods, Riccati and a new method based on Genetic algorithm. In this new proposed method, we use Genetic algorithm to achieve the optimum values of control coefficients. The results of the system simulation by Matlab indicate the effectiveness of new proposed system. When a new reference of air gap is needed or a new external force is added, the proposed system could omit the vibration and shake of the train coupe and so, passengers feel more comfortable.

Trapped particle stability for the kinetic stabilizer

Science.gov (United States)

Berk, H. L.; Pratt, J.

2011-08-01

A kinetically stabilized axially symmetric tandem mirror (KSTM) uses the momentum flux of low-energy, unconfined particles that sample only the outer end-regions of the mirror plugs, where large favourable field-line curvature exists. The window of operation is determined for achieving magnetohydrodynamic (MHD) stability with tolerable energy drain from the kinetic stabilizer. Then MHD stable systems are analysed for stability of the trapped particle mode. This mode is characterized by the detachment of the central-cell plasma from the kinetic-stabilizer region without inducing field-line bending. Stability of the trapped particle mode is sensitive to the electron connection between the stabilizer and the end plug. It is found that the stability condition for the trapped particle mode is more constraining than the stability condition for the MHD mode, and it is challenging to satisfy the required power constraint. Furthermore, a severe power drain may arise from the necessary connection of low-energy electrons in the kinetic stabilizer to the central region.

Motion stability of high-speed maglev systems in consideration of aerodynamic effects: a study of a single magnetic suspension system

Science.gov (United States)

Wu, Han; Zeng, Xiao-Hui; Yu, Yang

2017-12-01

In this study, the intrinsic mechanism of aerodynamic effects on the motion stability of a high-speed maglev system was investigated. The concept of a critical speed for maglev vehicles considering the aerodynamic effect is proposed. The study was carried out based on a single magnetic suspension system, which is convenient for proposing relevant concepts and obtaining explicit expressions. This study shows that the motion stability of the suspension system is closely related to the vehicle speed when aerodynamic effects are considered. With increases of the vehicle speed, the stability behavior of the system changes. At a certain vehicle speed, the stability of the system reaches a critical state, followed by instability. The speed corresponding to the critical state is the critical speed. Analysis reveals that when the system reaches the critical state, it takes two forms, with two critical speeds, and thus two expressions for the critical speed are obtained. The conditions of the existence of the critical speed were determined, and the effects of the control parameters and the lift coefficient on the critical speed were analyzed by numerical analysis. The results show that the first critical speed appears when the aerodynamic force is upward, and the second critical speed appears when the aerodynamic force is downward. Moreover, both critical speeds decrease with the increase of the lift coefficient.

Co-simulation of heavy truck tire dynamics and electronic stability control systems (phase A).

Science.gov (United States)

2009-07-01

Electronic stability control (ESC) systems have been proven to be an effective means of preventing instability and loss of control on both passenger vehicles and heavy trucks. In addition, roll stability algorithms are an effective means of reducing ...

Preliminary hazards analysis of thermal scrap stabilization system. Revision 1

International Nuclear Information System (INIS)

Lewis, W.S.

1994-01-01

This preliminary analysis examined the HA-21I glovebox and its supporting systems for potential process hazards. Upon further analysis, the thermal stabilization system has been installed in gloveboxes HC-21A and HC-21C. The use of HC-21C and HC-21A simplified the initial safety analysis. In addition, these gloveboxes were cleaner and required less modification for operation than glovebox HA-21I. While this document refers to glovebox HA-21I for the hazards analysis performed, glovebox HC-21C is sufficiently similar that the following analysis is also valid for HC-21C. This hazards analysis document is being re-released as revision 1 to include the updated flowsheet document (Appendix C) and the updated design basis (Appendix D). The revised Process Flow Schematic has also been included (Appendix E). This Current revision incorporates the recommendations provided from the original hazards analysis as well. The System Design Description (SDD) has also been appended (Appendix H) to document the bases for Safety Classification of thermal stabilization equipment

Electrical Grid Stability Enhancement using Smart Home Frequency-response Grid -Friendly Appliance System

Directory of Open Access Journals (Sweden)

Muawiya A. Kaigama

2016-03-01

Full Text Available Load shedding is a powerful scheme used for corrective and preventive measures; corrective to restore system’s stability and preventive to avoid catastrophic failure. However, the affected end users are deprived of power supply absolutely with no choice. This paper presents the design, development, feasibility and merits of Frequency-response Grid -Friendly Appliance System (FRGFAS in a smart home. FRGFAS is a decentralized Adaptive Load Shaving(ALS device that supports grid’s system stability by sensing grid’s frequency deterioration level and turns ON/OFF loads accordingly. The FRGFAS permits end users to carry out load shaving at their scale of preference in smart homes via flexible demand responses and automates outdoor lighting to optimum operational hours. FRGFAS obviate load shedding by shaving loads whenever the system is in distress and reset loads supply to the normal state when it stabilizes, this Consequently increases the end user comfort zone and averts a blackout.

Improved Polynomial Fuzzy Modeling and Controller with Stability Analysis for Nonlinear Dynamical Systems

Directory of Open Access Journals (Sweden)

Hamed Kharrati

2012-01-01

Full Text Available This study presents an improved model and controller for nonlinear plants using polynomial fuzzy model-based (FMB systems. To minimize mismatch between the polynomial fuzzy model and nonlinear plant, the suitable parameters of membership functions are determined in a systematic way. Defining an appropriate fitness function and utilizing Taylor series expansion, a genetic algorithm (GA is used to form the shape of membership functions in polynomial forms, which are afterwards used in fuzzy modeling. To validate the model, a controller based on proposed polynomial fuzzy systems is designed and then applied to both original nonlinear plant and fuzzy model for comparison. Additionally, stability analysis for the proposed polynomial FMB control system is investigated employing Lyapunov theory and a sum of squares (SOS approach. Moreover, the form of the membership functions is considered in stability analysis. The SOS-based stability conditions are attained using SOSTOOLS. Simulation results are also given to demonstrate the effectiveness of the proposed method.

ISO 9001: Quality management systems. The experience of the centre for hydro graphic studies (CEDEX); ISO 9001: Sistemas de gestion de la calidad. La experiencia del Centro de Estudios Hidrograficos del CEDEX

Energy Technology Data Exchange (ETDEWEB)

Alonso Garcia, A. M.; Aviles Garcia, J.; Gonzalez Ramos, M. E.; Diago Sanchez, I.

2010-07-01

The Spanish government is developing several plans and programmes in order to introduce the quality culture and instruments in the various institutions, looking for efficient and committed public organizations, providers of quality services. To achieve the commitment to improve and modernize the Administration, the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX) has decided the implementation and certification of a Quality Management System according to ISO 9001: standard at the Centro de Estudios Hidrograficos as pilot experience. (Author) 5 refs.

Impact of Wind Power on the Angular Stability of a Power System

Directory of Open Access Journals (Sweden)

Djemai NAIMI

2008-06-01

Full Text Available Wind energy conversion systems are very different in nature from conventional generators. Therefore dynamic studies must be addressed in order to integrate wind power into the power system. Angular stability assessment of wind power generator is one of main issues in power system security and operation. The angular stability for the wind power generator is determined by its corresponding Critical Clearing Time (CCT. In this paper, the effect of wind power on the transient fault behavior is investigated by replacing the power generated by two main types of wind turbine, increasing gradually a rate of wind power penetration and changing the location of wind resources. The simulation analysis was established on a 14 bus IEEE test system by PSAT/Matlab, which gives access to an extensive library of grid components, and relevant wind turbine model.

A switched state feedback law for the stabilization of LTI systems.

Energy Technology Data Exchange (ETDEWEB)

Santarelli, Keith R.

2009-09-01

Inspired by prior work in the design of switched feedback controllers for second order systems, we develop a switched state feedback control law for the stabilization of LTI systems of arbitrary dimension. The control law operates by switching between two static gain vectors in such a way that the state trajectory is driven onto a stable n - 1 dimensional hyperplane (where n represents the system dimension). We begin by briefly examining relevant geometric properties of the phase portraits in the case of two-dimensional systems to develop intuition, and we then show how these geometric properties can be expressed as algebraic constraints on the switched vector fields that are applicable to LTI systems of arbitrary dimension. We then derive necessary and sufficient conditions to ensure stabilizability of the resulting switched system (characterized primarily by simple conditions on eigenvalues), and describe an explicit procedure for designing stabilizing controllers. We then show how the newly developed control law can be applied to the problem of minimizing the maximal Lyapunov exponent of the corresponding closed-loop state trajectories, and we illustrate the closed-loop transient performance of these switched state feedback controllers via multiple examples.

Application of a Modal Approach in Solving the Static Stability Problem for Electric Power Systems

Science.gov (United States)

Sharov, J. V.

2017-12-01

Application of a modal approach in solving the static stability problem for power systems is examined. It is proposed to use the matrix exponent norm as a generalized transition function of the power system disturbed motion. Based on the concept of a stability radius and the pseudospectrum of Jacobian matrix, the necessary and sufficient conditions for existence of the static margins were determined. The capabilities and advantages of the modal approach in designing centralized or distributed control and the prospects for the analysis of nonlinear oscillations and rendering the dynamic stability are demonstrated.

Wind Power Impact to Transient and Voltage Stability of the Power System in Eastern Denmark

DEFF Research Database (Denmark)

Rasmussen, Joana; Jørgensen, Preben; Palsson, Magni Thor

2005-01-01

Voltage stability, transient stability and reactive power compensation are extremely important issues for largescale integration of wind power in areas distant from the main transmission system in Eastern Denmark. This paper describes the application of a dynamic wind farm model in simulation...... studies for assessments of a large wind power penetration. The simulation results reveal problems with voltage stability due to the characteristic of wind turbine generation as well as the inability of the power system to meet the reactive power demand. Furthermore, the established model is applied...

Calculation and Simulation Study on Transient Stability of Power System Based on Matlab/Simulink

Directory of Open Access Journals (Sweden)

Shi Xiu Feng

2016-01-01

Full Text Available The stability of the power system is destroyed, will cause a large number of users power outage, even cause the collapse of the whole system, extremely serious consequences. Based on the analysis in single machine infinite system as an example, when at the f point two phase ground fault occurs, the fault lines on either side of the circuit breaker tripping resection at the same time,respectively by two kinds of calculation and simulation methods of system transient stability analysis, the conclusion are consistent. and the simulation analysis is superior to calculation analysis.

Modeling and Stability Analysis of Wedge Clutch System

Directory of Open Access Journals (Sweden)

Jian Yao

2014-01-01

Full Text Available A wedge clutch with unique features of self-reinforcement and small actuation force was designed. Its self-reinforcement feature, associated with different factors such as the wedge angle and friction coefficient, brings different dynamics and unstable problem with improper parameters. To analyze this system, a complete mathematical model of the actuation system is built, which includes the DC motor, the wedge mechanism, and the actuated clutch pack. By considering several nonlinear factors, such as the slip-stick friction and the contact or not of the clutch plates, the system is piecewise linear. Through the stability analysis of the linearized system in clutch slipping phase, the stable condition of the designed parameters is obtained as α>arctan⁡(μc. The mathematical model of the actuation system is validated by prototype testing. And with the validated model, the system dynamics in both stable and unstable conditions is investigated and discussed in engineering side.

Stability and Hopf bifurcations in a competitive Lotka-Volterra system with two delays

International Nuclear Information System (INIS)

Song Yongli; Han Maoan; Peng Yahong

2004-01-01

We consider a Lotka-Volterra competition system with two delays. We first investigate the stability of the positive equilibrium and the existence of Hopf bifurcations, and then using the normal form theory and center manifold argument, derive the explicit formulas which determine the stability, direction and other properties of bifurcating periodic solutions