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Number of results: 52
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Abstract

The paper deals with the problems of designing observers and unknown input observers for discrete-time Lipschitz non-linear systems. In particular, with the use of the Lyapunov method, three different convergence criteria of the observer are developed. Based on the achieved results, three different design procedures are proposed. Then, it is shown how to extend the proposed approach to the systems with unknown inputs. The final part of the paper presents illustrative examples that confirm the effectiveness of the proposed techniques. The paper also presents a MATLAB® function that implements one of the design procedures.

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Authors and Affiliations

J. Korbicz
M. Witczak
V. Puig
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Abstract

The paper presents the results of the studies on the determination of the degree of dependence between the adjusted observations, on the basis of the levels of their coexistence in a network. An approximate model is proposed making it possible to estimate that dependence without the necessity to perform the adjustment procedure. This model can be applied in the procedures of gross error detection in observations. Additionally, a supplementary algorithm to determine the coexistence levels for the observations on the grounds of the matrix of coefficients in the observation equations is presented.
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Authors and Affiliations

Mieczysław Kwaśniak
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Abstract

The paper presents the method and results of measurements carried out at four secular points: P, — Wilczekodden, P2 — Hyttevika, P3 — Gashamna and P4 — Treskelodden. No essential changes were found in the distribution of the anomalous field ΔT with respect to the results of observations made in 1979.

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Authors and Affiliations

Andrzej Koblański
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Abstract

A complete parametric approach is proposed for the design of the Luenberger type function Kx observers for descriptor linear systems. Based on a complete parametric solution to a class of generalized Sylvester matrix equations, parametric expressions for all the coefficient matrices of the observer are derived. The approach provides all the degrees of design freedom, which can be utilized to achieve some additional design requirements. An illustrative example shows the effect of the proposed approach.

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Authors and Affiliations

G.R. Duan
A.G. Wu
W.N. Hou
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Abstract

The article proposes a new method of reproducing the angular speed of the rotor of a cage induction machine designed for speed observers based on the adaptive method. In the proposed solution, the value of the angular speed of the rotor is not determined by the classical law of adaptation using the integrator only by an algebraic relationship. Theoretical considerations were confirmed by simulation and experimental tests.

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Authors and Affiliations

M. Morawiec
P. Kroplewski
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Abstract

The time period of a jet engines full acceleration (from idle run rotating speed to full thrust) is a very important operational parameter. Minimization of this period is an important problem to be solved during the design of the fuel supply and control system. There are many methods of acceleration process control, especially in the case of engines with complicated design configurations. This work presents the problem of acceleration of a simple, single spool turbine jet engine with a so-called stable geometry, in which only one input (control) signal exists - fuel flow rate. Two methods of acceleration control consisting of limitation of the maximum allowable temperature of working medium in front of and behind the turbine in transient states were analyzed. In order to avoid difficulties associated with the direct measurement of actual temperatures, the so-called nonlinear engine observer was applied. With the use of the computer simulation method it was proven that the control algorithm with the limited maximum temperature in front of the turbine makes it possible the shortening of the acceleration time period significantly in comparison with a similar algorithm, that realizes the limitation of temperature behind the turbine.
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Authors and Affiliations

Wojciech I. Pawlak
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Abstract

This paper deals with the problem of stabilization by an estimated state feedback for a family of nonlinear time-delay Takagi-Sugeno fuzzy parameterized systems. The delay is supposed to be constant where the parameter-dependent controls laws are used to compensate the nonlinearities which are formulated in terms of linear matrix inequalities (LMIs). Based on the Lyapunov- Krasovskii functionals, global exponential stability of the closed-loop systems is achieved. The controller and observer gains are able to be separately designed even in the presence of modeling uncertainty and state delay. Finally, a numerical example is given to show the applicability of the main result.
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Authors and Affiliations

Nizar Hadj Taieb
1
Mohamed Ali Hammami
2
François Delmotte
3

  1. University of Sfax, IPEIS Sfax, Tunisia
  2. University of Sfax, Faculty of Sciences of Sfax, Tunisia
  3. University of Artois, Bethune, France
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Abstract

The aim of the work is to develop and test an algorithm of adjustment of geodetic observations, resistant to gross errors (method of robust estimations), with the use of the damping function, proposed by the author. Detailed formulae of the damping function as a component of the objective function in a modified classic least squares method were derived. The selection criteria for the controlling parameters of the damping functions have also been provided. The effectiveness of the algorithm has been verified with two numerical examples. The results have been analysed with reference to the methods of resistant compensation, which apply other damping functions, e.g. Hampel's function.
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Authors and Affiliations

Tadeusz Gargula
ORCID: ORCID
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Abstract

The observation inflation effect consists in the fact that observing an action being performed can create false memories that this action has actually been performed by the observer. The present study examined the relationship between this effect and interrogative suggestibility. A procedure based on the Gudjonsson Suggestibility Scale was used to assess two kinds of suggestibility: the tendency to yield to suggestive questions (Yield) and the tendency to change answers after feedback (Shift). The participants first watched a film depicting a woman performing simple activities and performed various activities themselves during the film. In order to determine whether the observation inflation effect occurred, the participants performed a source-monitoring test. The observation inflation effect was replicated. Observation inflation correlated positively with Yield but not with Shift. This pattern of results can be explained by the fact these two indicators are different aspects of interrogative suggestibility. Shift is more related to social influence, while Yield is more cognitive in its nature.

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Authors and Affiliations

Magdalena Kękuś
Regina Dziubańska
Iga Komęza
Iwona Dudek
Klaudia Chylińska
Malwina Szpitalak
ORCID: ORCID
Romuald Polczyk
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Abstract

This work addresses the problem of adaptive observer design for nonlinear systems satisfying incremental quadratic constraints. The output of the system includes nonlinear terms, which puts an additional strain on the design and feasibility of the observer, which is guaranteed under the satisfaction of an LMI, and a set of algebraic constraints. A particular case where the output nonlinearity matches the unknown parameter coefficient is also discussed. The result is illustrated through a numerical example for the chaos synchronization of the Rössler system.
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Authors and Affiliations

Lazaros Moysis
1
Meenakshi Tripathi
2
Mahendra Kumar Gupta
2
Muhammad Marwan
3
Christos Volos
1

  1. Laboratory of Nonlinear Systems – Circuits & Complexity, Physics Department, Aristotle University of Thessaloniki, Thessaloniki, Greece
  2. Department of Mathematics, National Institute of Technology Jamshedpur, Jamshedpur, India
  3. Department of Mathematics, Zhejiang Normal University, Jinhua, China
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Abstract

We consider in this work a class of finite dimensional time-varying linear disturbed systems. The main objective of this work is to studied the optimal control which ensures the remediability of a disturbance of time-varying disturbed systems. The remediability concept consist to find a convenient control which bringing back the corresponding observation of disturbed system to the normal one at the final time. We give firstly some characterisations of compensation and in second party we find a control which annul the output of the system and we show also that the Hilbert Uniqueness Method can be used to solve the optimal control which ensure the remediability.Ageneral approachwas given to minimize the linear quadratic problem. Examples and numerical simulations are given.
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Authors and Affiliations

El Mostafa Magri
1
Chadi Amissi
1
Larbi Afifi
1
Mustapha Lhous
1

  1. Fundamental and Applied Mathematics Laboratory, Department of Mathematics and Computer Science, Faculty of Sciences Ain Chock, Hassan II University of Casablanca, B.P.5366-Maârif, Casablanca, Morocco
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Abstract

The present-day methods of supervising the operational use of jet engines are based, among other things, on computerised procedures of monitoring and recording various failure modes, including the surge. This dangerous mode of operation of a turbojet engine occurs quite commonly while operating it. In some cases, it could result even in the engine destruction. What has been presented in this study is the way of applying a non-linear observer of a one-spool single-flow turbojet to generate a computer algorithm to detect the surging. An exemplary application of such an algorithm to monitor the surging that occurs in the K-15 engine has also been shown.
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Authors and Affiliations

Wojciech I. Pawlak
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Abstract

A large class of nonlinear systems can be represented or well approximated by Takagi- Sugeno (TS) fuzzy models, which in theory can approximate a general nonlinear system to an arbitrary degree of accuracy. The TS fuzzy model consists of a fuzzy rule base. The rule antecedents partition a given subspace of the model variables into fuzzy regions, while the consequent of each rule is usually a linear or affine model, valid locally in the corresponding region. In this paper, the observer design problem for a T-S fuzzy system subject to Lypschitz perturbation is investigated. First, an observer of Kalman type is designed to estimate the unknown system states. Then, the class of one-sided Lipschitz for a TS fuzzy system subject to a sufficient condition on the bound is studied. The challenges are discussed and some analysis oriented tools are provided. An example is given to show the applicability of the main result.
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Authors and Affiliations

Francois Delmotte
1
Mohamed Ali Hammami
2
Nour El Houda Rettab
2

  1. University of Artois, Bethune, France
  2. University of Sfax, Faculty of Sciences of Sfax, Tunisia
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Abstract

The paper studies the fault identification problem for linear control systems under the unmatched disturbances. A novel approach to the construction of a sliding mode observer is proposed for systems that do not satisfy common conditions required for fault estimation, in particular matching condition, minimum phase condition, and detectability condition. The suggested approach is based on the reduced order model of the original system. This allows to reduce complexity of sliding mode observer and relax the limitations imposed on the original system.
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Bibliography

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[14] V. Filaretov, A. Zuev, A. Zhirabok, and A. Protcenko: Development of fault identification system for electric servo actuators of multilink manipulators using logic-dynamic approach. J. Control Science and Engineering, 2017 (2017), 1–8, DOI: 10.1155/2017/8168627.
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Authors and Affiliations

Alexey Zhirabok
1 2
Alexander Zuev
2
Vladimir Filaretov
3
Alexey Shumsky
1

  1. Far Eastern Federal University, Vladivostok 690091, Russia
  2. Institute of Marine Technology Problems, Vladivostok, 690091, Russia
  3. Institute of Automation and Processes of Control, Vladivostok, 690014, Russia
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Abstract

The studied problem in this paper, treat the issue of state and fault estimation using a fuzzy observer in the case of unmeasurable decision variable for Discrete-Time Takagi-Sugeno Singular Sytems (DTSSS). First, an augmented system is introduced to gather state and fault into a single vector, then on the basis of Singular Value Decomposition (SVD) approach, this observer is designed in explicit form to estimate both of state and fault of a nonlinear singular system. The exponential stability of this observer is studied using Lyapunov theory and the convergence conditions are solved with Linear Matrix Inequalities (LMIs). Finally a numerical example is simulated, and results are given to validate the offered approach.
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Authors and Affiliations

Khaoula Aitdaraou
1 2
Mohamed Essabre
3
Abdellatif El Assoudi
1 2
El Hassane El Yaagoubi
1 2

  1. Laboratory of High Energy Physics and Condensed Matter, Faculty of Science, Hassan II University of Casablanca, B.P 5366, Maarif Casablanca, Morocco
  2. ECPI, Department of Electrical Engineering, ENSEM Hassan II University of Casablanca, B.P 8118, Oasis Casablanca, Morocco
  3. Laboratory of Materials, Energy and Control Systems, Faculty of Sciences and Technologies Mohammedia, Hassan II University of Casablanca, Morocco
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Abstract

Generalized observers are proposed to relax the existing conditions required to design Luenberger observers for rectangular linear descriptor systems with unknown inputs. The current work is focused on designing index one generalized observers, which can be naturally extended to higher indexes. Sufficient conditions in terms of system operators for the existence of generalized observers are given and proved. Orthogonal transformations are used to derive the results. A physical model is presented to show the usefulness of the proposed theory.
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Authors and Affiliations

Abhinav Kumar
1
Mahendra Kumar Gupta
1 2

  1. Department of Mathematics, National Institute of Technology Jamshedpur, Jharkhand, India
  2. School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Khordha, Odisha, 752050 – India
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Abstract

W strap is a crucial surface support component for underground coal mine roadways. In this study, the failure characteristics of the W strap in the field are discussed, and the loading characteristics of the strap and the faceplate are numerically and experimentally analysed. Afterwards, a loading apparatus capable of reappearing the loading environment of the strap in the field is fabricated. This loading device, combined support systems consisting of a bolt, faceplate and strap is tested under different simulated strata conditions. Failure patterns of the strap are evaluated by the 3D scanning method, and proper selection of a faceplate is explored. Results indicate that a domed faceplate can achieve a favourable supporting effect on strata, and thus it is favoured compared with a square domed faceplate. In addition, rock cavity and rock integrity beneath the strap are essential factors determining the servicing life of the overall supporting system.
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Authors and Affiliations

Xiaowei Feng
1
ORCID: ORCID
Fei Xue
2
ORCID: ORCID
Xiaotian Feng
3
ORCID: ORCID
Tongyang Zhao
2
ORCID: ORCID

  1. China University of Mining and Technology, China
  2. Shaoxing University, Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province, China
  3. Xi’an University of Architecture and Technology, Politecnico di Milano, China
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Abstract

The present paper consists of two parts. The first part presents theoretical foundations of Msplit, estimation with reference to the previous author's paper (Wiśniewski, 2009). This time, some probabilistic assumptions are described in detail. A new quantity called f-information is also introduced to formulate the split potential in more general way. The main aim of this part of the paper is to generalize the target function of Msplit estimation that is the basis for a new formulation of the optimization problem. Such problem itself as well as its solution are presented in this part of the paper. The second part of the paper presents some special case of Mspli, estimation called squared Mspli, estimation (also with reference to the mentioned above paper of the author). That part presents a new solution and development in the theory of this version of M,plit estimation and some numerical examples that show properties of the method and its application scope.
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Authors and Affiliations

Zbigniew Wiśniewski
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Abstract

This part of the paper presents particular case of Msplit estimation called a squared Msplit estimation whose target function is based on convex squared functions. One can find here theoretical foundations and algorithm of the squared Msplit estimation as well as some numerical examples.
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Authors and Affiliations

Zbigniew Wiśniewski
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Abstract

In the research it has been assumed that an observation corresponds to a measured height difference of a levelling section while a pseudo-observation corresponds to a sum of observations for consecutive levelling sections which make up a levelling line. Relations between observations and pseudo-observations are shown. It has also been assumed that observations are not correlated. The study compares Helmert - Pranis-Praniewicz. algorithm of parametric. multi-group (parallel) least squares adjustment of observations with the algorithm of rwo-stage least squares adjustment of levelling network. The two-stage adjustment consists of least squares adjustment of pseudo-observations and then the adjustment of observations, which is carried out separately for each levelling line. It was shown that normal equations concerning heights of nodal points, created on the basis of pseudo-observations, are identical to the reduced normal equations formed on the basis of observations in multi-group adjustment. So, adjusted heights of nodal points and their variance-covariance matrix are the same in the case of adjustment of observations and in the case of adjustment of pseudo-observations. Following a brief presentation of known algorithm of height computation for intermediate benchmarks of levelling lines there is shown the proof that the value of a square root of the a posteriori variance of unit weight 1110, known also as mean square error of a typical observation/pseudo-observation, is the same in the case of adjustment of observations and in the case of adjustment of pseudo-observations. The conclusion states that the results of two-stage adjustment and rigorous least squares adjustment of observations are identical.
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Authors and Affiliations

Idzi Gajderowicz
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Abstract

The paper presents an iterative identification method dedicated for industrial processes. The method consists of two steps. In the first step, a MISO system is identified with the Modulating Functions Method to obtain sub-models with a common denominator. In the second step, the obtained subsystems are re-identified. This procedure enables to obtain the set of models with different denominators of the transfer functions. The algorithmwas used for on-line identification of a glass conditioning process. Identification window is divided into intervals, in which the models can be updated based on recent process data, with the use of the integral state observer. Results of the performed simulations for the identified models are compared with the historical process data.
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Authors and Affiliations

Witold Byrski
1
Michał Drapała
1

  1. Department of Automatic Control and Robotics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland
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Abstract

The highly dynamic and unsteady characteristics of the cavitating flow cause many negative effects such as erosion, noise and vibration. Also, in the real application, it is inevitable to neglect the dissolved air in the water, although it is usually neglected in the previous works to reduce the complexity. The novelty of the present work is analysing the impact of dissolved air on the average/unsteady characteristics of Venturi flow by conducting sets of experimental tests. For this purpose, two different amounts of dissolved air at five pressure levels (i.e. five different sets of cavitation numbers) were considered in the study of cavitating flow inside a Venturi nozzle. The fast Fourier transform analysis of pressure fluctuations proved that the shedding frequency reduces almost by 50% to 66%, depending on the case, with adding the amount of dissolved air. However, the reduction of 14% to 25% is achieved by the vibration transducers. On the other hand, the cavity enlarges as well as bubbly flow is observed in the test chamber at a higher level of dissolved air. Furthermore, it is observed that the re-entrant jet, as the main reason for the cavity detachment, is more effective for the detachment process in cases with a lower level of dissolved air, where the re-entrant jet front penetrates more toward the leading edge.
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Authors and Affiliations

Emad Hasani Malekshah
1
Włodzimierz Wróblewski
1
Krzysztof Bochon
1
Mirosław Majkut
1
Krzysztof Rusin
1

  1. Silesian University of Technology, Department of Power Engineering and Turbomachinery, Konarskiego 18, 44-100 Gliwice, Poland
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Abstract

The paper presents the results of an experiment with sugar-industry waste (molasses) as an organic carbon source for denitrification. The investigations concern the influence of untreated molasses and molasses after pretreatment (hydrolyzed molasses) and variable COD/N ratio (6.0: 5.0: 4.0) on denitrification efficiency and kinetics. Moreover, sludge production, in dependence on tested carbon source, was estimated. Al COD/N ratio 6 and 5, regardless or applied organic carbon source (untreated molasses. hydrolyzed molasses), the denitrification efficiency was over 98%,. However. from kinetic analysis it results that a kind or carbon source and COD/N ratio have an effect on denitrification rate. The highest nitrate removal rate - 9.5 mg N,0/(dm-1-h) was obtained al COD/N = 6 in the reactor with hydrolyzed molasses as a carbon source and the lowest - 5.14 mg N,0J(dm1-h) in reactor with untreated molasses at COD/N = 5.0. The lowering or COD/N ratio to 4 caused decrease otthe process efficiency to 27.6% (untreated molasses) and 44.3% (hydrolyzed molasses). Hydrolyzed molasses as a carbon source caused higher production of activated sludge. In reactors with untreated molasses Y equals 0.40 mg VSS/rng COD at COD/N ratio 6 and 0.31 111g VSS/111g COD at COD/N ratio 5. In reactors with molasses alter hydrolysis Y, were 1.35-lolcl and 1.5-lold higher, respectively. Since, the molasses hydrolysis results in rising costs of wastewater treatment and cause higher sludge production, untreated molasses seems to be a more suitable carbon source for dcniuification.
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Authors and Affiliations

Dorota Kulikowska
Karolina Dudek
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Abstract

In this paper, we propose sensorless backstepping control of a double-star induction machine (DSIM). First, the backstepping approach is designed to steer the flux and speed variables to their references and to compensate uncertainties. Lyapunov”s theory is used and it demonstrates that the dynamic tracking of trajectories tracking is asymptotically stable. Second, unfortunately, this law control called sophisticated is a major problem which leads to the necessity of using a mechanical sensor (speed, load torque). This imposes an additional cost and increases the complexity of the montage. In practice, this variable is unknown and its measurement is expensive. To restrain this problem we estimate speed and load torque by using a Luenberger observer (LO). Simulation results are provided to illustrate the performance of the proposed approach in high and low variable speeds and load torque disturbance.

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Authors and Affiliations

Hadji Chaabane
Khodja Djalal Eddine
Chakroune Salim

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