Adaptive backstepping sliding mode control for feedforward uncertain systems

Output tracking backstepping sliding mode control for feedforward uncertain systems is considered in this article. Feedforward systems are not usually transformable to the parametric semi-strict feedback form, and they may include unmatched uncertainties consisting of disturbances and unmodelled dynamics terms. The backstepping method presented in this article, even without uncertainties differs from that of Ríos-Bolívar and Zinober [Ríos-Bolívar, M. and Zinober, A.S.I. (1999), ‘Dynamical Adaptive Sliding Mode Control of Observable Minimum Phase Uncertain Nonlinear Systems’, in Variable Structure Systems: Variable Structure Systems, Sliding Mode and Nonlinear Control, eds., K.D. Young and Ü. Özgüner. Ozguner, London, Springer-Verlag, pp. 211–236; Ríos-Bolívar, M., and Zinober, A.S.I. (1997a), ‘Dynamical Adaptive Backstepping Control Design via Symbolic Computation’, in Proceedings of the 3rd European Control Conference, Brussels]. In this article, the backstepping is not a dynamical method as in Ríos-Bolívar and Zinober (1997a Ríos-Bolívar, M and Zinober, ASI. 1997a. Dynamical Adaptive Sliding Mode Output Tracking Control of a Class of Nonlinear Systems. International Journal of Robust and Nonlinear Control, 7: 387–405.  [Google Scholar], 1999), since at each step, the control and map input remain intact, and the differentiations of the control are not used. Therefore, the method can be introduced as static backstepping. Two different controllers are designed based upon the backstepping approach with and without sliding mode. The dynamic and static backstepping methods are applied to a gravity-flow/pipeline system to compare two methods.     

Adaptive learning control design for robotic manipulators driven by permanent magnet synchronous motors

On the basis of the ideas recently presented in Tomei and Verrelli (Tomei, P., and Verrelli, C.M. (2010 Tomei, P and Verrelli, CM. 2010. Learning Control for Induction Motor Servo Drives with Uncertain Rotor Resistance. International Journal of Control, 83: 1515–1528. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]), ‘Learning Control for Induction Motor Servo Drives with Uncertain Rotor Resistance’, International Journal of Control, 83, 1515–1528) and Marino et al. (Marino, R., Tomei, P., and Verrelli, C.M. (2011 Marino, R, Tomei, P and Verrelli, CM. 2011. Robust Adaptive Learning Control for Nonlinear Systems with Extended Matching Unstructured Uncertainties. International Journal of Robust and Nonlinear Control, Early View, doi: 10.1002/rnc.1720 [Google Scholar]), ‘Robust Adaptive Learning Control for Nonlinear Systems with Extended Matching Unstructured Uncertainties’, International Journal of Robust and Nonlinear Control, Early View, doi: 10.1002/rnc.1720), we briefly show how the adaptive learning control design proposed in Liuzzo and Tomei (Liuzzo, S., and Tomei, P. (2009 Liuzzo, S and Tomei, P. 2009. Global Adaptive Learning Control of Robotic Manipulators by Output Error Feedback. International Journal of Adaptive Control and Signal Processing, 23: 97–109.  [Google Scholar]), Global Adaptive Learning Control of Robotic Manipulators by Output Error Feedback, International Journal of Adaptive Control and Signal Processing, 23, 97–109) can be extended to robotic manipulators driven by nonsalient-pole (surface) permanent magnet synchronous motors. Unstructured uncertain dynamics (that is no parameterisation is available for the uncertainties) of the rigid robot with rotational joints are considered as well as uncertainties in stator resistances of the synchronous motors are taken into account. Two solutions with clear stability proofs are presented: a global decentralised control via state feedback and a semi-global control via output feedback. Output tracking of known periodic reference signals and learning of corresponding uncertain input reference signals are achieved. Available results in the literature are thus improved since no simplification concerning negligible electrical motor dynamics is used.     

Non-linear output feedback tracking control for AUVs in shallow wave disturbance condition

This article presents a non-linear output feedback tracking controller deisgn for autonomous underwater vehicles (AUVs) operating in shallow water area. In a shallow water environment, significant disturbances due to shallow water waves affect the motion of marine vehicles greatly. Since it is not energy efficient to counteract the oscillatory disturbances due to waves, it is critical to obtain the wave information or wave induced disturbance information and design an energy efficient controller to reduce the action of actuators to counteract wave disturbances to avoid wear and tear on actuators. In this article, a non-linear observer is first designed to estimate the low frequency (LF) motion of AUVs and to filter out wave-frequency (WF) motion of AUVs due to shallow water wave by using position and attitude measurements. Based on the designed observer, a non-linear output feedback controller is subsequently derived by using the observer backstepping technique. By using this approach, the AUV achieves global exponential tracking without excessive energy consumption to counteract the wave disturbance and also avoids excessive wear and tear on thrusters. Global exponential stability (GES) of overall observer-controller system is proved through Lyapunov stability theory. A set of simulations is carried out by using the KAMBARA (Silpa-Anan 2001 Silpa-Anan, C. 2001. “Autonomous Underwater Robot: Vision and Control”. In Master's thesis, The Australian National University.  [Google Scholar]) AUV model to demonstrate the performance of the proposed observer and output feedback controller.     

Stochastic resonance–a nonlinear control theory interpretation

Stochastic resonance (SR) is an effect that has been known (Benzi, R., Sutera, A., and Vulpiani, A. (1981 Chapeau-Blondeau, F. 1997. Input-Output Gains for Signal in Noise in Stochastic Resonance. Physics Letters A, 232: 41–48.  [Google Scholar]), ‘The Mechanism of Stochastic Resonance’, Journal of Physics, A14, L453–L457) for almost three decades and has been extensively studied in biology, statistics, signal processing and in numerous other eclectic areas (Wiesenfeld, K., and Moss, F. (1995 Xu, B, Jiang, Z-P, Wu, X and Repperger, DW. 2009. Investigation of Two-dimensional Parameter-Induced Stochastic Resonance and Applications in Nonlinear Image Processing. Journal of Physics A–Mathematical and Theoretical, 42: 145207, 1-45207, 9 [Google Scholar]), ‘Stochastic Resonance and the Benefits of Noise: From Ice Ages to Crayfish and Squids’, Nature, 373, 33–36). Herein, a nonlinear control theory analysis is conducted on how to better understand the class of systems that may exhibit the SR effect. Using nonlinear control theory methods, equilibrium points are manipulated to create the SR response (similar to shaping dynamical response in a phase plane). From this approach, a means of synthesising and designing the appropriate class of nonlinear systems is introduced. New types of nonlinear dynamics that demonstrate the SR effects are discovered, which may have utility in control theory as well as in many diverse applications. A numerical simulation illustrates some powerful attributes of these systems.     

Evaluation of CMODIS-measured radiance by a hyperspectral model

A Chinese Moderate Resolution Imaging Spectrometer (CMODIS), an ocean colour sensor onboard the ‘Shenzhou-3’ spaceship, was launched on 25 March 2002. Because CMODIS was not equipped with any onboard calibration systems, there were major concerns about the accuracy of the CMODIS radiance measurements as well as the reliability of the data processing and oceanographic applications. To clarify these concerns, a hyperspectral satellite remote sensing radiance evaluation model (HRSREM) was developed, based on a radiative transfer model with consideration of multiple-scattering effects and atmospheric absorption. The model was used to compute the total radiance at the top of the atmosphere (TOA) to evaluate the CMODIS-derived radiance. The accuracy of the model was validated by Gordon's algorithms [Wang, M. and Gordon, H.R., 1994 Wang, M. and Gordon, H.R. 1994. A simple, moderately accurate, atmospheric correction algorithm for SeaWiFS. Remote Sensing of Environment, 50: 231–239. [Crossref], [Web of Science ®] , [Google Scholar], A simple, moderately accurate, atmospheric correction algorithm for SeaWiFS. Remote Sensing of Environment, 50, pp. 231–239] and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data. The results show that the average relative error in the atmospheric scattering radiance computed by the HRSREM is less than 1.5% and the average error in the HRSREM TOA radiance is about 3.0%. Therefore, the HRSREM can be used to evaluate the accuracy of CMODIS-measured radiance. The results show that CMODIS has relatively small errors at the visible bands but large errors at the near-infrared (NIR) bands with an average error of more than 100%. The laboratory calibration coefficients are not reliable and the CMODIS data were recalibrated by the HRSREM to recover the archive of CMODIS data.     

Evaluation of language measure parameters for discrete event manufacturing systems with multiproduct machines

The concept of language measure provides a mathematical framework for quantitative analysis and synthesis of discrete event supervisory control systems. The language measure is assigned two parameters, namely the state transition cost matrix and the state cost vector. In a recent paper (Khatab and Nourelfath 2006 Khatab, A and Nourelfath, M. 2006. Analytical approach to evaluate language measure parameters for discreteevent supervisory control. Int. J. Control, 79: 688–706.  [Google Scholar]), an analytical approach has been formulated to evaluate the language measure parameters for discrete event manufacturing systems composed of several monoproduct machines, i.e., each machine is able to perform only one kind of product. This paper generalizes these results to the multiproduct case, i.e., to the case where each machine in the manufacturing system is able to perform different kinds of products. The proposed approach is based on the theory of Markov stochastic processes and Kronecker algebra. The main advantage of the proposed approach is that the mathematical expressions of the system language measure parameters are derived from data of individual elementary machines without generating the whole, possibly huge, system state space.     

Backstepping-based cooperative and adaptive tracking control design for a group of underactuated AUVs in horizontal plan

In this paper, we investigate new implementable cooperative adaptive backstepping controllers for a group of underactuated autonomous vehicles that are communicating with their local neighbours to track a time-varying virtual leader of which the relative position may only be available to a portion of the team members. At the kinematic cooperative control level of the autonomous underwater vehicle, the virtual cooperative controller is basically designed on a proportional and derivative consensus algorithm presented in Ren (2010) Ren, W. (2010). Consensus tracking under directed interaction topologies: Algorithms and experiments. IEEE Transactions on Control Systems Technology, 18, 230–237.[Crossref], [Web of Science ®] , [Google Scholar], which involves velocity information from local neighbours. In this paper, we propose a new design algorithm based on singular perturbation theory that precludes the use of the neighbours’ velocity information in the cooperative design. At the dynamic cooperative control level, calculation of the partial derivatives of some stabilising functions which in turn will contain velocity information from the local neighbours is required. To facilitate the implementation of the cooperative controllers, we propose a command filter approach technique to avoid analytic differentiation of the virtual cooperative control laws. We show how Lyapunov-based techniques and graph theory can be combined together to yield a robust cooperative controller where the uncertain dynamics of the cooperating vehicles and the constraints on the communication topology which contains a directed spanning tree are explicitly taken into account. Simulation results with a dynamic model of underactuated autonomous underwater vehicles moving on the horizontal plane are presented and discussed.     

Approximation error in PDE-based modelling of vehicular platoons

We study the problem of how much error is introduced in approximating the dynamics of a large vehicular platoon by using a partial differential equation, as was done in Barooah, Mehta, and Hespanha [Barooah, P., Mehta, P.G., and Hespanha, J.P. (2009 Barooah, P, Mehta, PG and Hespanha, JP. 2009. Mistuning-based Decentralised Control of Vehicular Platoons for Improved Closed Loop Stability. IEEE Transactions on Automatic Control, 54: 2100–2113. [Crossref], [Web of Science ®] , [Google Scholar]), ‘Mistuning-based Decentralised Control of Vehicular Platoons for Improved Closed Loop Stability’, IEEE Transactions on Automatic Control, 54, 2100–2113], Hao, Barooah, and Mehta [Hao, H., Barooah, P., and Mehta, P.G. (2011), ‘Stability Margin Scaling Laws of Distributed Formation Control as a Function of Network Structure’, IEEE Transactions on Automatic Control, 56, 923–929]. In particular, we examine the difference between the stability margins of the coupled-ordinary differential equations (ODE) model and its partial differential equation (PDE) approximation, which we call the approximation error. The stability margin is defined as the absolute value of the real part of the least stable pole. The PDE model has proved useful in the design of distributed control schemes (Barooah et al. 2009 Barooah, P, Mehta, PG and Hespanha, JP. 2009. Mistuning-based Decentralised Control of Vehicular Platoons for Improved Closed Loop Stability. IEEE Transactions on Automatic Control, 54: 2100–2113. [Crossref], [Web of Science ®] , [Google Scholar]; Hao et al. 2011 Hao, H, Barooah, P and Mehta, PG. 2011. Stability Margin Scaling Laws of Distributed Formation Control as a Function of Network Structure. IEEE Transactions on Automatic Control, 56: 923–929. [Crossref], [Web of Science ®] , [Google Scholar]); it provides insight into the effect of gains of local controllers on the closed-loop stability margin that is lacking in the coupled-ODE model. Here we show that the ratio of the approximation error to the stability margin is O(1/N), where N is the number of vehicles. Thus, the PDE model is an accurate approximation of the coupled-ODE model when N is large. Numerical computations are provided to corroborate the analysis.     

Models of the effect of teleoperation transmission delay on robot movement time

Abstract

Recent research of [Scholcover and Gillan (2018 Scholcover, F., and D. J. Gillan. 2018. “Using Temporal Sensitivity to Predict Performance under Latency in Teleoperation.” Human Factors 60.1:80–91. doi:10.1177/0018720817734727.[Crossref], [Web of Science ®] , [Google Scholar])] has shown experimentally that system transmission delay has a linear effect on the time taken to perform a complex tracking task with a simple teleoperated robot. This note shows that, for the case of moving a robot through a straight path, this relationship is predicted. The result is a simple modification of Drury’s law to take into account the system delay. This work extends the model for performance under intermittent illumination of Drury to the effects of fixed delays in task performance, occurring with teleoperated robots. In all cases, there was empirical evidence for the predicted linear relationship.

Practitioner summary: When there is a delay in system response for robotic teleoperation between a control input and system output, movement time (MT) is increased and the increased times are linearly related to the system delay. This is true for zero and first-order control and for delays occurring before and after the control action.     

Capture of shrinking targets

‘Shrinking targets’ are targets whose size diminishes with time. The task studied is a modification of Fitts' (1954 Fitts, P. M. 1954. The information capacity of the human motor system in controlling the amplitude of movement. Journal of Experimental Psychology, 67(6): 381–391. [Crossref] , [Google Scholar]) paradigm, with the difference that, as soon as the movement is started, the target size reduces at a constant rate until it finally vanishes. Very little research has been reported on this problem apart from Johnson and Hart (1987 Johnson, W. W. and Hart, S. G. Step tracking shrinking targets. Proceedings of the Human Factors Society 31st annual meeting. October1987, New York City. pp.248–252. Santa Monica, CA: HFES.  [Google Scholar]) and Hancock and Caird (1993 Hancock, P. A. and Caird, J. K. 1993. Experimental evaluation of a model of mental workload. Human Factors, 35(3): 413–429. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Two experiments are reported aimed at determining the parameters that affect the movement time and the probability of capturing a target when there are different amplitudes of movement, target widths and shrink rates. A multiplicative model is required to describe movement time data, which is dependent on Fitts' Index of Difficulty, the shrink rate and the product of these two variables. An alternative model describes the critical movement time, for a specified probability of target capture, in a modified form of Fitts' Law.

Statement of Relevance: Modifications of Fitts' Law have been developed for many different movement tasks. Shrinking targets occur in circumstances such as gunnery and in computer games, where a target is moving away from the person. An expression is developed for the critical time to capture the target in terms of a modified form of Fitts' Law.     

The performance of discrete linear time-varying control for l2 disturbance rejection

This paper extends the results of Zhang et.al. (1997 Zhang, C., Zhang, J. and Furuta, K. 1997. Performance analysis of discrete periodically time varying controllers. Automatica, 33: 619–634. [Crossref] , [Google Scholar]) for linear periodically time-varying control to general linear time-varying (LTV) control. It is shown that linear time-invariant (LTI) control provides strictly better control performance than linear strictly time-varying control if l₂ disturbance rejection of LTI plants is considered. The analysis is carried out in the frequency domain. This approach provides not only new results on disturbance rejection of LTV control but also some new insight into the properties of general LTV systems.     

MGR Hash Functions

Abstract

GOST-R 34.11-94 is a Russian standard cryptographic hash function that was introduced in 1994 by the Russian Federal Agency for the purposes of information processing, information security, and digital signature. Mendel et al. (2008 Mendel, F., N. Pramstaller, C. Rechberger, M. Kontak, and J. Szmidt. 2008. Cryptanalysis of the GOST hash function, Advances in Cryptology – CRYPTO 2008, vol. 5157, 162–178. [Google Scholar]) and Courtois and Mourouzis (2011 Courtois, N., and T. Mourouzis. 2011. Black-box collision attacks on the compression function of the GOST hash function. SECRYPT. Proceedings of the International Conference on Security and Cryptography, 325–332, IEEE. [Google Scholar]) found attacks on the compression function of the GOST-R structure that were basically weaknesses of the GOST-R block cipher (GOST 28147–89, 1989 GOST 28147-89. 1989. Systems of the information treatment, cryptographic security, algorithms of the cryptographic transformation (in Russian). [Google Scholar]). Hence in 2012, it was updated to GOST-R 34.11-2012, which replaced the older one for all its applications from January 2013. GOST-R 34.11-2012 is based on a modified Merkle-Damgård construction. Here we present a modified version of GOST-R 34.11-2012 (Modified GOST-R (MGR) hash). The design of the MGR hash is based on wide-pipe construction, which is also a modified Merkle-Damgård construction. MGR is much more secure as well as three times faster than GOST-R 34.11-2012. Advanced Encryption Standard (AES)-like block ciphers have been used in designing the compression function of MGR because AES is one of the most efficient and secure block ciphers and has been evaluated for more than 14?years. A detailed statistical analysis with a few other attacks on MGR is incorporated into this paper.     

On the classical solution to the linear-constrained minimum energy problem

Minimum energy problems involving linear systems with quadratic performance criteria are classical in optimal control theory. The case where controls are constrained is discussed in Athans and Falb (1966 Athans, M and Falb, PL. 1966. Optimal Control. An Introduction to the Theory and Its Applications, New York: McGraw-Hill Book Co.  [Google Scholar]) [Athans, M. and Falb, P.L. (1966), Optimal Control: An Introduction to the Theory and Its Applications, New York: McGraw-Hill Book Co.] who obtain a componentwise optimal control expression involving a saturation function expression. We show why the given expression is not generally optimal in the case where the dimension of the control is greater than one and provide a numerical counterexample.     

Asymptotically fast polynomial matrix algorithms for multivariable systems

We present the asymtotically fastest known algorithms for some basic problems on univariate polynomial matrices: rank; nullspace; determinant; generic inverse reduced form (Giorgi et al. 2003, Storjohann 2003 Storjohann, A. 2003. “High-order lifting and integrality certification”. In J. Symb. Comp. Edited by: Giusti, M and Pardo, LM. Vol. 36, 613–648. Nice, France, 3, , USA Special issue International Symposium on Symbolic and Algebraic Computation (ISSAC’2002). Guest editors: [Google Scholar], Jeannerod and Villard 2005 Jeannerod, C-P and Villard, G. 2005. Essentially optimal computation of the inverse of generic polynomial matrices. J. Comp., 21: 72–86.  [Google Scholar], Storjohann and Villard 2005 Storjohann, A and Villard, G. July 2005. “Computing the rank and a small nullspace basis of a polynomial matrix”. In Proc. International Symposium on Symbolic and Algebraic Computation, 309–316. Beijing, China: ACM Press.  [Google Scholar]). We show that they essentially can be reduced to two computer algebra techniques, minimal basis computations and matrix fraction expansion/reconstruction, and to polynomial matrix multiplication. Such reductions eventually imply that all these problems can be solved in about the same amount of time as polynomial matrix multiplication. The algorithms are deterministic, or randomized with certified output in a Las Vegas fashion.     

The motion planning problem and exponential stabilisation of a heavy chain. Part I†

A model of a heavy chain system with a punctual load (tip mass) in the form of a system of partial differential equations is interpreted as an abstract semigroup system on a Hilbert state space. Our aim is to solve the output motion planning problem of the same nature as in the case of an unloaded heavy chain (Grabowski, P. (2003 Grabowski, P. 2003. Abstract Semigroup Model of Heavy Chain System with Application to a Motion Planning Problem. Proceedings of 9th IEEE International Conference: Methods and Models in Automation and Robotics. 25–28 August2003, Mi?dzyzdroje, Poland. pp.77–86. (IS1-2-3.PDF) [Google Scholar]), ‘Abstract Semigroup Model of Heavy Chain System with Application to a Motion Planning Problem’, in Proceedings of 9th IEEE International Conference: Methods and Models in Automation and Robotics, 25–28 August, Mi?dzyzdroje, Poland, pp. 77–86 (IS1-2-3.PDF)). In order to solve this problem we first analyse its well-posedness and some basic properties. Next, we solve the output motion planning problem using a substitute of the inverse of the input–output operator represented in terms of the Laplace transforms. A problem of exponential stabilisation is also formulated and solved using a stabiliser of the colocated type. The exponential stabilisation is proved using the method of Lyapunov functionals combined with some frequency-domain tools. The method of Lyapunov functionals can be replaced by the spectral or exact controllability approach as shown in the second part (Grabowski, P. (2008 Grabowski, P. 2008. ‘The Motion Planning Problem and Exponential Stabilisation of a Heavy Chain. Part II’. Opuscula Mathematica, 28: 481–505. (2008) (Special issue dedicated to the memory of Professor Andrzej Lasota) [Google Scholar]), ‘The Motion Planning Problem and Exponential Stabilisation of a Heavy Chain. Part II’, Opuscula Mathematica, 28 (2008 Grabowski, P. 2008. ‘The Motion Planning Problem and Exponential Stabilisation of a Heavy Chain. Part II’. Opuscula Mathematica, 28: 481–505. (2008) (Special issue dedicated to the memory of Professor Andrzej Lasota) [Google Scholar]) (Special issue dedicated to the memory of Professor Andrzej Lasota), 481–505) of the present article. A laboratory setup which allows verification of the results in practice is described in detail. Its dynamical model is used as an example to illustrate the theoretical results.     

Joint influence of online store attributes and offline operations on performance of multichannel retailers

This study examines the synergistic interchange between online and offline operations. To this end, this study proposed a multichannel performance model integrating Herzberg's (Herzberg 1966 Herzberg, F. 1966. Work and the nature of man, Cleveland, OH: World Publishing.  [Google Scholar]: Work and the Nature of Man, World Publishing, Cleveland, OH) motivation-hygiene theory and Thorndike's (Thorndike 1920 Thorndike, E. L. 1920. A constant error in psychological ratings. Journal of Applied Psychology, 4: 25–29. [Crossref] , [Google Scholar]: J. Appl. Psychol., 4, 25 – 29) halo effect, and empirically tested it. The essence of the model was that e-satisfaction is formed by a varying influence of online (basic and marketing-related attributes) and offline (firm reputation, consumer offline channel use, and consumer offline satisfaction) factors, which then increases e-loyalty. Analyses on a sample of 203 multichannel consumers revealed that, in general, the hypothetical paths were significant except in two cases. In a multichannel's online operation, marketing-related online attributes (e.g. merchandising) exerted significant influence on e-satisfaction, but basic attributes (e.g. security) did not. In a multichannel's offline operation, firm reputation and consumer offline satisfaction contributed to increasing e-satisfaction. Both firm reputation and consumer offline channel use increased consumer offline satisfaction, which in turn increased online satisfaction. However, consumer offline loyalty did not transfer to online loyalty. Theoretical and managerial implications were suggested based on findings.     

Continuous-time non-linear flatness-based predictive control: an exact feedforward linearisation setting with an induction drive example

A general flatness-based framework for non-linear continuous-time predictive control is presented. It extends the results of Fliess and Marquez (2000 Fliess, M and Marquez, R. 2000. Continuous-time Linear Predictive Control and Flatness: A Module-theoretic Setting with Examples. International Journal of Control, 73: 606–623. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) to the non-linear case. The mathematical setting, which is valid for multivariable systems, is provided by the theory of flatness-based exact feedforward linearisation introduced by the authors (Hagenmeyer and Delaleau 2003b Hagenmeyer, V and Delaleau, E. 2003b. Exact Feedforward Linearization Based on Differential Flatness. International Journal of Control, 76: 537–556. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Thereby differential flatness does not only yield an easy calculation of the predicted trajectories considering the respective system constraints, but allows to use simple linear feedback parts in a two-degree-of-freedom control structure. Moreover, this formalism permits one to handle non-minimum phase systems, and furthermore to deal with parameter uncertainties and exogenous perturbations. Respective robustness analysis tools are available. Finally, an induction drive example is discussed in detail and experimental results for this fast electro-mechanical system are presented.     

Decryption oracle slide attacks on T-310

T-310 is an important Cold War cipher (Schmeh 2006 Schmeh, K. 2006. The East German encryption machine T-310 and the algorithm it used. Cryptologia 30 (3):251–257.[Taylor &; Francis Online] , [Google Scholar]). It was the principal encryption algorithm used to protect various state communication lines in Eastern Germany throughout the 1980s. The cipher seems to be quite robust, and until now no researcher has proposed an attack on T-310. This article studies decryption oracle and slide attacks on T-310.     

A Novel High Quality High Capacity Image Hiding Scheme Based on Image Compression and an Optical Pixel Adjustment Process

ABSTRACT

Image hiding methods embed a secret image into a host image. The resultant stego-image does not attract the interceptors that would not detect the differences between the host image and the stego-image. To exploit the great developments in the area of image compression and to improve the quality of stego-image, this paper proposes a new method to embed the secret image into the host image. Basically, the secret image is compressed and then embedded into host image. The embedding method is based on the Optimal Pixel Adjustment Process (OPAP) and genetic algorithm. In the paper we addressed the important issues to build such systems. The experimental results showed that the proposed method can improve the quality from 60% to 80% when compared with the simple Least Significant Bit (LSB) replacement methods. Adding to that, the mean square error of the stego-image is much lower compared with other methods (Chan & Cheng, 2004 Chan, C.K. and Cheng, L.M. 2004. Hiding data in images by simple LSB substitution. Pattern Recognition, 37(3): 469–474. [Crossref], [Web of Science ®] , [Google Scholar]; Chang, Hsiao, & Chan, 2003 Chang, C.C., Hsiao, J.Y. and Chan, C.S. 2003. Finding optimal least-significant-bit substitution in image hiding by dynamic programming strategy. Pattern Recognition, 36(7): 1583–1595. [Crossref], [Web of Science ®] , [Google Scholar]; Thien & Lin, 2003 Thien, C.C. and Lin, J.C. 2003. A simple and high-hiding capacity method for hiding digit-by-digit data in images based on modulus function. Pattern Recognition, 36(12): 2875–2881. [Crossref], [Web of Science ®] , [Google Scholar]; Tseng, Chan, Ho, & Chu, 208; Wang, Lin, & Lin, 2001 Wang, R.Z., Lin, C.F. and Lin, J.C. 2001. Image hiding by optimal LSB substitution and genetic algorithm. Pattern Recognition, 34(3): 671–683. [Crossref], [Web of Science ®] , [Google Scholar]). Also, the proposed technique improves capacity. In other words, we can embed a secret image with size 450?×?450 inside a hosting image with size 512?×?512.