Rajko Svečko

Design and evaluation of an adaptive icon toolbar

As information systems become increasingly important in many different domains, the potential to adapt them to individual users and their needs also becomes more important. Adaptive user interfaces offer many possible ways to adjust displays and improve procedures for a users individual patterns of work. This paper describes an attempt to design an adaptive user interface in a computer environment familiar to many users. According to one classification of adaptive user interfaces, the adaptive bar described in this paper would be classified as a user-controlled self-adaptation system.At the users convenience, the adaptive bar offers suggestions for adding or removing command icons, based on the frequency and probability of specific commands. It also implements these changes once the user has agreed to them. Beyond the adaptive bar, the general behavior of the whole user interface does not change, thereby allowing the user to maintain a clear general model of the system. This paper describes the decision-making algorithm implemented in the bar. It also describes the bars self-adaptive behavior of displaying the frequency of each icons use through the icons size. Finally, we present some encouraging preliminary results of evaluations by users.

An adaptive short list for documents on the World Wide Web

University of Maribor School of Psychology University of MariborSmetanova 17 Georgia Institute of Technology Smetanova 17S1-2000 Maribor, Slovenia Atlanta, GA 30332 USA S1-2000 Maribor, Slovenia+386 62221 112 +1 4048948344 +386 62221 112debevc@uni-mb. si bmeyer@psy.tfe. gatech. edu rajko. svecko@tni-mb. siABSTRACTSince the World Wide Web (WWW) is so popular andgrowing so quickly, users have almost an intinite numberof sites to choose from. Bookmark features in web browsersallow users to easily record the sites that they would like tobe able to view again, without having to repeatedly searchthrough the WWW. However, bookmark lists for activeweb users can grow very long very quickly. Since user-maintained bookmark lists can easily grow long andsomewhat harder to use, it is usefil to have anautomatically maintained shorter list of useful sites.This paper describes an Adaptive Short List of commonlyused sites. This feature, when integrated into web browsingsoftware. would enable users to check the most probablesites quickly. without having to search through everybookmark they’ve ever created. We also present a decisionalgorithm for selecting sites to include in this list. Thegoal of this system is to determine the most appropriatesites to include in the Adaptive Short List. based on usagedata which the system collects and analyzes while the userworks.KeywordsUser interface, adaptive user interface, World Wide Web,intelligent system. user rnodellingINTRODUCTIONAs more and more information becomes available on theWorld Wide Web and as users discover more of thisinformation, the number of web sites to which they theywant ready access also grows. Web browsing software suchas Netscape [4] supports this need by providing a“bookmark feature. allowing users to return directly to

Strong stabilization servo controller with optimization of performance criteria

Synthesis of a simple robust controller with a pole placement technique and a H(∞) metrics is the method used for control of a servo mechanism with BLDC and BDC electric motors. The method includes solving a polynomial equation on the basis of the chosen characteristic polynomial using the Manabe standard polynomial form and parametric solutions. Parametric solutions are introduced directly into the structure of the servo controller. On the basis of the chosen parametric solutions the robustness of a closed-loop system is assessed through uncertainty models and assessment of the norm ‖•‖(∞). The design procedure and the optimization are performed with a genetic algorithm differential evolution - DE. The DE optimization method determines a suboptimal solution throughout the optimization on the basis of a spectrally square polynomial and Šiljaks absolute stability test. The stability of the designed controller during the optimization is being checked with Lipatovs stability condition. Both utilized approaches: Šiljaks test and Lipatovs condition, check the robustness and stability characteristics on the basis of the polynomials coefficients, and are very convenient for automated design of closed-loop control and for application in optimization algorithms such as DE.

Feedforward neural network position control of a piezoelectric actuator based on a BAT search algorithm

Abstract The precise positional controls of piezoelectric actuators (PEA) are problematic due to highly-nonlinear hysteresis behavior which is inherent in piezoelectric materials. In existing PEA positional control applications that are based only on neural networks, the obtained control response results are insufficient for practical usage. In this paper we apply a combined approach by using a feedforward neural network (FNN) jointly with a BAT search algorithm in order to improve the positional control of an X-PEA mechanism model by also taking into account the hysteresis behavior. The proposed positional controller was successfully implemented and it was capable of significantly improving the overall control response result of an X-PEA mechanism model by minimizing the overshoot value and steady-state error, and decreasing the settling time. In addition, the BAT search algorithm can also be used for training the FNN, optimizing the FNN topology and reducing the computational complexity. The presented simulation results confirmed that the proposed positional controller with combined approach provides better results compared to the classical FNN control approach.

An Optimal Robust Pole Placement with Fixed Transparent Controller Structure on the Basis of Nonnegativity of Even Spectral Polynomials

This paper presents the synthesis of an optimal robust controller with the use of pole placement technique. The presented method includes solving a polynomial equation on the basis of the chosen fixed characteristic polynomial and introduced parametric solutions with a known parametric structure of the controller. Robustness criteria in an unstructured uncertainty description with metrics of norm are for a more reliable and effective formulation of objective functions for optimization presented in the form of a spectral polynomial with positivity conditions. The method enables robust low-order controller design by using plant simplification with partial-fraction decomposition, where the simplification remainder is added to the performance weight. The controller structure is assembled of well-known parts such as disturbance rejection, and reference tracking. The approach also allows the possibility of multiobjective optimization of robust criteria, application of mixed sensitivity problem, and other closed-loop limitation criteria, where the common criteria function can be composed from different unrelated criteria. Optimization and controller design are performed with iterative evolution algorithm.

Multi-criteria optimal pole assignment robust controller design for uncertainty systems using an evolutionary algorithm

This paper presents the synthesis of an optimal robust controller design using the polynomial pole placement technique and multi-criteria optimisation procedure via an evolutionary computation algorithm – differential evolution. The main idea of the design is to provide a reliable fixed-order robust controller structure and an efficient closed-loop performance with a preselected nominally characteristic polynomial. The multi-criteria objective functions have quasi-convex properties that significantly improve convergence and the regularity of the optimal/sub-optimal solution. The fundamental aim of the proposed design is to optimise those quasi-convex functions with fixed closed-loop characteristic polynomials, the properties of which are unrelated and hard to present within formal algebraic frameworks. The objective functions are derived from different closed-loop criteria, such as robustness with metric ∞, time performance indexes, controller structures, stability properties, etc. Finally, the design results from the example verify the efficiency of the controller design and also indicate broader possibilities for different optimisation criteria and control structures.

Quasipolynomial Approach to Simultaneous Robust Control of Time-Delay Systems

A control law for retarded time-delay systems is considered, concerning infinite closed-loop spectrum assignment. An algebraic method for spectrum assignment is presented with a unique optimization algorithm for minimization of spectral abscissa and effective shaping of the chains of infinitely many closed-loop poles. Uncertainty of plant delays of a certain structure is considered in a sense of a robust simultaneous stabilization. Robust performance is achieved using mixed sensitivity design, which is incorporated into the addressed control law.

Use of acoustic emission testing in injection moulding process

This paper presents the experimental results regarding acoustic emission signals measured during the injection moulding of those standard test specimens commonly used for examining the shrinkage behaviour of various thermoplastic materials. The acoustic emission was measured on a new injection mould and injection mould with the visible cracks on the cavitys surface. Two resonant 150 kHz piezoelectric AE sensors were attached to tool steel inserts via AE waveguides. The results of acoustic emission testing on the crack defected tool steel insert revealed higher acoustic emission activity compared with that captured on the brand new engraving insert under same processing conditions. Specimens produced with a new and defected tool were scanned with an optical 3D digitiser. Results of the experiments confirm that acoustic emission measuring during injection moulding of polymer materials is promising technique to characterise integrity of injection moulding tool regarding occurrence of cracks.