Wyniki wyszukiwania - Biblioteka Nauki

1

Analysis of the Effect of Time Delay on the Integrated GNSS/INS Navigation Systems

100%

Yang C. K. , Shim D. S.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2013

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tom Vol. 7, no. 2

199--204

EN

The performance of tightly coupled GNSS/INS integration is known to be better than that of loosely coupled GNSS/INS integration. However, if the time synchronization error occurs between the GNSS receiver and INS(Inertial Navigation System), the situation reverses. The performance of loosely coupled GNSS/INS integration and tightly coupled GNSS/INS integration is analyzed and compared due to time synchronization error by computer simulation.

2

Dynamics of the tumor-immune system competition - the effect of time delay

100%

Galach M.

International Journal of Applied Mathematics and Computer Science

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2003

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tom 13

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nr 3

395-406

EN

The model analyzed in this paper is based on the model set forth by V.A. Kuznetsov and M.A. Taylor, which describes a competition between the tumor and immune cells. Kuznetsov and Taylor assumed that tumor-immune interactions can be described by a Michaelis-Menten function. In the present paper a simplified version of the Kuznetsov-Taylor model (where immune reactions are described by a bilinear term) is studied. On the other hand, the effect of time delay is taken into account in order to achieve a better compatibility with reality.

3

Delay-induced state transition and resonance in periodically driven tumor model with immune surveillance

100%

Yang T. , Han Q. , Zeng C. , Wang H. , Fu Y. , Zhang C.

Open Physics

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2014

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tom 12

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nr 6

383-391

EN

The phenomenon of stochastic resonance (SR) in a tumor growth model under the presence of immune surveillance is investigated. Time delay and cross-correlation between multiplicative and additive noises are considered in the system. The signal-to-noise ratio (SNR) is calculated when periodic signal is introduced multiplicatively. Our results show that: (i) the time delay can accelerate the transition from the state of stable tumor to that of extinction, however the correlation between two noises can accelerate the transition from the state of extinction to that of stable tumor; (ii) the time delay and correlation between two noises can lead to a transition between SR and double SR in the curve of SNR as a function of additive noise intensity, however for the curve of SNR as a function of multiplicative noise intensity, the time delay can cause the SR phenomenon to disappear, and the cross-correlation between two noises can lead to a transition from SR to stochastic reverse-resonance. Finally, we compare the SR phenomenon for the multiplicative periodic signal with that for additive periodic signal in the tumor growth model with immune surveillance.

4

Stochastic tumor growth system with two different kinds of time delay

100%

Dou C.-S. , Li D. , Wang C.-J.

Open Physics

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2011

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tom 9

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nr 3

616-620

EN

The dynamical properties of a noise-driven tumor cell growth system are investigated when there exist two different kinds of time delays, in the deterministic and fluctuating forces, respectively. Using the approximation probability density approach, the delayed Fokker-Planck equation is obtained. The effects of two different time delays on the stationary probability distribution (SPD), the mean value and the mean passage time (MFPT) are discussed. It is found that the time delay τ1 in the deterministic force can enhance tumor cell number, while the time delay τ2 in the fluctuating force can induce a decrease in tumor cell numbers. On the other hand, while τ1 can hold back the extinction of tumor cells, τ2 can speed up their extinction.

5

Multivariable predictive control considering time delay for load-frequency control in multi-area power systems

100%

Daniar S. , Shiroei M. , Aazami R.

Archives of Control Sciences

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2016

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tom Vol. 26, no. 4

527--549

EN

In this paper, a multivariable model based predictive control (MPC) is proposed for the solution of load frequency control (LFC) in a multi-area interconnected power system. The proposed controller is designed to consider time delay, generation rate constraint and multivariable nature of the LFC system, simultaneously. A new formulation of the MPC is presented to compensate time delay. The generation rate constraint is considered by employing a constrained MPC and economic allocation of the generation is further guaranteed by an innovative modification in the predictive control objective function. The effectiveness of proposed scheme is verified through time-based simulations on the standard 39-bus test system and the responses are then compared with the proportional-integral controller. The evaluation of the results reveals that the proposed control scheme offers satisfactory performance with fast responses.

6

A time interval generator with the STM32 microcontroller

100%

Sawicki M. , Różyc K.

Measurement Automation Monitoring

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2015

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tom Vol. 61, No. 7

296--298

EN

The paper presents a concept of utilization of counter-timer circuits built in popular microcontrollers for generating precise time intervals. The main aim was to generate pulses START and STOP wholly in hardware without using a core of the microcontroller. This enables minimizing the value of time jitter of the generated time intervals and allows the use of remaining resources of the microcontroller freely. The introduced method of generation exploits the possibility of simultaneous synchronization of TIM2 and TIM3 timers from an overloaded TIM1 timer. Dependent timers work in One Pulse Mode. START and STOP signals are generated by PWM channels of individual timers. PWM channels can be configured independently which gives the possibility to generate START and STOP pulses of different polarity and width. Generation of a time interval can be triggered automatically (TIM1) or through one of the inputs of the microcontroller. The implemented generator is characterized by the generated range of time interval from 0 to 100 s and the resolution of 40 ns. The jitter of 100 ps was obtained. The concept is suitable to apply in any microcontroller of the STM32 family. It allows the generation of precise and adjustable delays in the application without the need to significantly expand a hardware part of the device.

7

Optimization of information flows of logistic supply chain

100%

Oliskevych M.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2015

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tom Vol. 4, No 4

71--76

EN

This research is devoted to the problem of information flows of logistic system of goods supplying. Information messages appear at moment of material flows which should be consider as discrete one. It gives an ability to research all changes that can occur to input material flow. Moreover, it makes a possibility to obtain analytic dependence of showers of effectively of system from parameter of information and material flows interaction. Logistic chain was first decomposed on four basic logistic operation such as distributing, unitizing, breaking up, speed up. Three parameters were used to characterize them. All that parameters depend of main flow of goods, packets, transport packets. The principle of solid material flows was applied. Then points of control were defined. It was researched two parts of main problem. First deals with a increasing material flows andconsequences of logistic chain adopting after that. Second deals with an decreasing flow. Control of several ways of different changes of logistic schemas depends of existed information flows which may be sent at one of defined control point. The criteria of material and information flows interaction effectiveness is total time delay per unit. The principle of streamlining is just-in-time. Deviation of appointed moment of operation starting or finishing equals to additional costs. The result consists the dependence of total delay per unit from structure of information flows. It can be used as a condition of real logistic schema optimization.

8

Estimation of the time delay of hydroacoustic signals for passive location of underwater objects

100%

Makar A.

Archives of Acoustics

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2004

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tom Vol. 29, no. 3

435-445

EN

In this paper a method of time delay estimation of acoustic signals radiated in water has been shown. The source of these signals is a moving ship. The gradient adaptive method of minimizing the error has been used. An algorithm of estimation using this method and the results of estimation the real signals radiated by a moving ship have been presented.

9

Effects of time delay on the statistical fluctuations for a bistable system driven by cross-correlated noises

100%

Zeng C.-h. , Zhou X.-f. , Tao S.-f.

Open Physics

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2009

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tom 7

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nr 3

534-540

EN

We study the effects of time delay on the normalized correlation function C(s) and the associated relaxation time T c for a bistable system with correlations between multiplicative and additive white noises under the condition of small time delay. Using the projection operator method, the expressions of T c and C(s) are obtained. Based on numerical computations, it is found that the delay time τ slows down the rate of fluctuation decay of dynamical variable for the presence of positive feedback intensity (∈ > 0), while speeds up the rate of fluctuation decay of dynamical variable for the presence of negative feedback intensity (∈ < 0). The effects of the delay time τ on the T c and C(s) are entirely opposite for ∈ 〉 0 and ∈ < 0.

10

Fault tolerant control of switched nonlinear systems with time delay under asynchronous switching

100%

Xiang Z. , Wang R. , Chen Q.

International Journal of Applied Mathematics and Computer Science

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2010

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tom 20

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nr 3

497-506

EN

This paper investigates the problem of fault tolerant control of a class of uncertain switched nonlinear systems with time delay under asynchronous switching. The systems under consideration suffer from delayed switchings of the controller. First, a fault tolerant controller is proposed to guarantee exponentially stability of the switched systems with time delay. The dwell time approach is utilized for stability analysis and controller design. Then the proposed approach is extended to take into account switched time delay systems with Lipschitz nonlinearities and structured uncertainties. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.

11

On delay-dependent stability for neutral delay-differential systems

100%

Han Q.-L.

International Journal of Applied Mathematics and Computer Science

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2001

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tom 11

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nr 4

965-976

EN

This paper deals with the stability problem for a class of linear neutral delay-differential systems. The time delay is assumed constant and known. Delay-dependent criteria are derived. The criteria are given in the form of linear matrix inequalities which are easy to use when checking the stability of the systems considered. Numerical examples indicate significant improvements over some existing results.

12

Uniform exponential stabilization of distributed bilinear parabolic time delay systems with bounded feedback control

100%

Tsouli A. , Ouarit M.

Archives of Control Sciences

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2022

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tom Vol. 32, No. 2

257--278

EN

In this paper we deal with the problem of uniform exponential stabilization for a class of distributed bilinear parabolic systems with time delay in a Hilbert space by means of a bounded feedback control. The uniform exponential stabilization problem of such a system reduces to stabilizing only its projection on a suitable finite dimensional subspace. Furthermore, the stabilizing feedback control depends only on the state projection on the finite dimensional subspace. An explicit decay rate estimate of the stabilized state is given provided that a non-standard weaker observability condition is satisfied. Illustrative examples for partial functional differential equations are displayed.

13

On the analytic properties of the S-matrix for the unknown interactions surrounded by centrifugal and rapidly decreasing potentials

88%

Olkhovsky V.

Open Physics

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2011

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tom 9

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nr 1

13-44

EN

The analytic structure of the non-relativistic unitary and non-unitary S-matrix is investigated for the cases of the unknown interactions with the unknown motion equations inside a sphere of radius a, surrounded by the centrifugal and rapidly decreasing (exponentially or by the Yukawian law or by the more rapidly decreasing) potentials. The one-channel case and special examples of many-channel cases are considered. Some kinds of symmetry conditions are imposed. The Schroedinger equation for r > a for the particle motion and the condition of the completeness of the correspondent wave functions are assumed. The connection of the obtained results with the usual (temporal) causality is examined. Finally a scientific program is presented as a clear continuation and extension of the obtained results.

14

Laplace transforms for MIMO SD systems with delay

88%

Lampe B. P. , Rosenwasser E. N.

Archives of Control Sciences

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2006

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tom Vol. 16, no. 4

363-381

EN

The paper constructs the Laplace transform of the solution with zero initial energy for a MIMO sampled-data system containing pure time-delays in its stationary elements. The properties of the Laplace transform as a function of the complex variable are studied.

15

Influence of time delay on fractional-order PI-controlled system for a second-order oscillatory plant model with time delay

88%

Sadalla T. , Horla D. , Giernacki W. , Kozierski P.

Archives of Electrical Engineering

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2017

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tom Vol. 66, nr 4

693--704

EN

The paper aims at presenting the influence of an open-loop time delay on the stability and tracking performance of a second-order open-loop system and continuoustime fractional-order PI controller. The tuning method of this controller is based on Hermite- Biehler and Pontryagin theorems, and the tracking performance is evaluated on the basis of two integral performance indices, namely IAE and ISE. The paper extends the results and methodology presented in previous work of the authors to analysis of the influence of time delay on the closed-loop system taking its destabilizing properties into account, as well as concerning possible application of the presented results and used models.

16

Robust L2 consensus of high-order swarm systems with time-varying delays

88%

Xi J. , Yao Z. , Liu G. , Zhong Y.

Control and Cybernetics

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2014

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tom Vol. 43, no. 1

59--77

EN

Consensus problems for high-order continuous-time swarm systems in directed networks with time delays, uncertainties and external disturbances are investigated. Firstly, the state space of a swarm system is decomposed into a consensus subspace (CS) and a complement consensus space (CCS). A necessary and sufficient condition for the system with time delays and uncertainties to achieve consensus is presented based on the state projection on CCS, and an explicit expression of the consensus function is shown on the basis of the state projection on CS. Then, a sufficient condition for the system to achieve consensus with a desired L2 performance is given. Finally, numerical simulations are shown to demonstrate theoretical results.

17

Time-varying time-delay estimation for nonlinear systems using neural networks

88%

Tan Y.

International Journal of Applied Mathematics and Computer Science

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2004

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tom 14

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nr 1

63-68

EN

Nonlinear dynamic processes with time-varying time delays can often be encountered in industry. Time-delay estimation for nonlinear dynamic systems with time-varying time delays is an important issue for system identification. In order to estimate the dynamics of a process, a dynamic neural network with an external recurrent structure is applied in the modeling procedure. In the case where a delay is time varying, a useful way is to develop on-line time-delay estimation mechanisms to track the time-delay variation. In this paper, two schemes called direct and indirect time-delay estimators are proposed. The indirect time-delay estimator considers the procedure of time-delay estimation as a nonlinear programming problem. On the other hand, the direct time-delay estimation scheme applies a neural network to construct a time-delay estimator to track the time-varying time-delay. Finally, a numerical example is considered for testing the proposed methods.

18

µ-Synthesis : an algebraic approach

88%

Dlapa M. , Prokop R.

Archives of Control Sciences

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2004

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tom Vol. 14, no. 1

59-71

EN

In the paper the problem of the robust control of continuous-time systems via [my]-synthesis is investigated. The robust control design is formulated as a local minimalization of the peak of the structured singular value. The control parameters are derived throught polynomial Diophantine equations as a pole placement principle. the poles of the nominal feedback loop are the variables for minimization which was performed by a direct search method. The procedure provided the final controller of a simple PID structure, which was applied to a system with time delay as a perturbation and the results were compared with the D-K iteration, which gave a more complex solution.

19

Enhanced IMC synthesis for tracking control of magnetic levitation system

88%

Elumalai V. K. , Subramanian R. G. , Reddipogu J. S. D. , Srinivasan S. , Agrawal S.

Archives of Electrical Engineering

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2018

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tom Vol. 67, nr 2

293–-306

EN

This paper presents an enhanced internal model control (EIMC) scheme for a time-delayed second order unstable process, which is subjected to exogenous disturbance and model variations. Even though the conventional internal model control (IMC) can provide an asymptotic tracking response with desired stability margins, the major limitation of conventional IMC is that it cannot be applied for an unstable system because a small exogenous disturbance can trigger the control signal to grow unbounded. Hence, modifying the conventional IMC structure to guarantee the internal stability, we present an EIMC scheme which can offer better trade-off between setpoint tracking and disturbance rejection characteristics. To improve the load disturbance rejection characteristics and attenuate the effect of sensor noise, we solve the selection of controller gains as an H∞ optimization problem. One of the key aspects of the EIMC scheme is that the robustness of the closed loop system can be tuned via a single tuning parameter. The performance of the EIMC scheme is experimentally assessed on a magnetic levitation plant for reference tracking application. Experimental results substantiate that the EIMC scheme can effectively counteract the inherent time delay in the model and offer precise tracking, even in the presence of exogenous disturbance. Moreover, by comparing the trajectory tracking performance of EIMC with that of the proportional integral velocity (PIV) controller through cumulative power spectral density (CPSD) of the tracking error, we show that the EIMC can offer better low frequency servo response with minimal vibrations.

20

Fractional order Riemann-Liouville integral inclusions with two independent variables and multiple delay

88%

Abbas S. , Benchohra M.

Opuscula Mathematica

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2013

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tom Vol. 33, no. 2

209--222

EN

In the present paper we investigate the existence of solutions for a system of integral inclusions of fractional order with multiple delay. Our results are obtained upon suitable fixed point theorems, namely the Bohnenblust-Karlin fixed point theorem for the convex case and the Covitz-Nadler for the nonconvex case.