Abstract: This paper gives an extension to the Iterative Feedback Tuning (IFT) approach that ensures the performance improvement of state feedback control systems for single input processes. IFT employs sensitivity functions and the experiments conducted on the real-world control system in order to provide an efficient way to deal with the nonlinear or ill-defined processes when the model-dependent Linear-Quadratic Regulator (LQR) is not successful. An experimental setup is suggested to implement the real-time iterative calculation of the gradients in the minimization of the LQR’s objective function. The experimental results validate the performance of the proposed IFT algorithm in a mechatronics application which deals with the angular position controller for a DC servo system with actuator dead zone and control signal saturation. The results show the reduction of the LQR’s objective function for a single input process application.
Keywords: implementation; Iterative Feedback Tuning; mechatronics; state feedback control; real-time experiments
Abstract: Provisioning 3D video stream-based services online in an acceptable quality, even in a wireless access environment, is a big challenge for Future Internet service providers. Characterizing the necessary Quality of Service requirements is hard, since only a few empirical results are known about the user perceived 3D quality. In this paper a statistical analysis of subjective perception of 3D stereoscopic video Quality of Experience (QoE) are investigated with respect to network level QoS. The network is configured to demonstrate a real environment; thus, GPON-based aggregation is used. Our results show characteristics of QoE-QoS relationship in the case of 3D video playback. We also tackle the challenge by carrying out GPON-based transport network with IEEE802.11n standard based WiFi access measurements focusing the QoE of 3D content. And according to our results we propose cubic fitting function for modeling QoE-QoS relationship in the case of throughput degradation.
Keywords: 3D stereoscopic video; Quality of Experience-QoE; Quality of Service-QoS; GPON-based network; WiFi network; Mean Opinion Score-MOS; subjective evaluation
Abstract: This paper is focused on analysing the effects of the chosen colour space on image segmentation accuracy for a permanent quality control of the folding process. The folding process is one of the basic operations in print finishing, but during this converting operation the printed or non-printed substrates are exposed to high tensile stresses. These stresses can cause coating cracks on the folding line, which decrease the expected aesthetic feature or even the functionality of the product. High production efficiency of the folding process could be provided by a control system for automated visual inspection. Such a quality control algorithm was proposed by the authors in previous papers. Since the proposed algorithm relies on qualitative image segmentation, it is very important to determine all the factors which influence the segmentation quality. This paper investigates the influence of colour spaces. The applied image segmentation algorithm (Maximum Entropy) works on grey-scale images, and therefore only the luminance components of the five selected colour spaces (HSI, HSL, HSV, CIE Lab and CIE xyY) were used. The segmentation quality was determined by using six different measures (quantitative and qualitative), which were combined in order to obtain a single performance measure for algorithm evaluation.
Keywords: colour space; segmentation; fold quality
Abstract: This paper considers the creation of a transient vibration signal model established for signals generated in deep grove ball bearings with pitting (spalling) formulation on their inner race. The fault on the inner race was created artificially. The derivation of the signal model is based on data acquisition, signal filtering and parametric identification. A new filtering method is presented that is suitable to eliminate the effect of amplitude modulation and noise that usually arises in the case of bearing vibration measurements. We show that a three-parameter signal model is adequate to describe unmodulated transient pulses. Our signal model can be used in developing new bearing vibration analysis and condition monitoring methods.
Keywords: Condition monitoring; bearing vibration analysis; model identification
Abstract: The Anti-lock braking system (ABS) is an active safety device in road vehicles, which during hard braking maximizes the braking force between the tyre and the road irrespective of the road conditions. This is accomplished by regulating the wheel slip around its optimum value. Due to the high non-linearity of the tyre and road interaction, and uncertainties from vehicle dynamics, a standard PID controller will not suffice. This paper therefore proposes a non-linear control design using input-output feedback linearization approach. To enhance the robustness of the non-linear controller, an integral feedback method was employed. The stability of the controller is analysed in the Lyapunov sense. To demonstrate the robustness of the proposed controller, simulations were conducted on two different road conditions. The results from the proposed method exhibited a more superior performance and reduced the chattering effect on the braking torque compared to the performance of the standard feedback linearization method.
Keywords: anti-lock braking system; wheel slip; friction model; hybrid systems; feedback linearization; PID
Abstract: Model-based development methods are increasingly being applied in the production of software artifacts. The processing of visual models, within these frameworks, is an essential issue that can be addressed using graph rewriting techniques. The precise definition of graph rewriting-based model transformation requires that beyond the topology of the rules, further textual constraints be added. These constraints often appear repetitively in a transformation; therefore, constraint concerns crosscut the transformation. It is useful to define often applied constraints as physically separated modules and indicate the places where to use them. This effort provides solutions to structuring, modularizing and propagating repetitively occurring and crosscutting constraints. We propose an aspect-oriented approach that allows for consistent constraint management, in which repetitive and crosscutting constraints can be semi-automatically identified.
Keywords: Aspect-oriented constraints; Constraint aspects; Constraint modularization; Graph rewriting
Abstract: A plane problem of failure mechanics is considered for concentrically integrated cylinders. It is assumed that the drawing die (internal cylinder) is negative allowance strengthened by means of external cylinder (holder), and near the surface of the drawing die there are N arbitrarily located rectilinear cracks of length 2lk (k=1,2,...,N). Theoretical analysis on definition the negative allowance providing minimization of failure parameters (stress intensity factors) of drawing die was carried out on minimax criterion. A simplified method for minimization the failure parameters of a hard alloy drawing die was separately considered.
Keywords: hard-alloy drawing die; reinforcing cylinder; negative allowance; cracks; stress intensity factors; minimization of drawing die failure parameters
Abstract: The aim of this paper is to transform the model of the impedance controlled robot interaction with feedback delay to a Tensor Product (TP) type polytopic LPV model whereupon Linear Matrix Inequality (LMI) based control design can be immediately executed. The paper proves that the impedance model can be exactly represented by a finite element TP type poly- topic model under certain constrains. The paper also determines various further TP models with different advantages for control design. First, it derives the exact Higher Order Singular Value Decomposition (HOSVD) based canonical form, then it performs complexity trade-off to yield a model with less number of components but rather effective for LMI design. Then the pa- per presents various different types of convex TP model representations based on the non-exact model in order to investigate how convex hull manipulation can be performed on the model. Fi- nally the presented models are analyzed to validate the accuracy of the transformation and the resulting TP type polytopic LPV models. The paper concludes that these prepared models are ready for convex hull manipulation and LMI based control design.
Keywords: LPV/qLPV modeling; impedance conrol; complience control; time delay; telemanipulation; haptics
Abstract: In this paper, conjoint analysis is used to gain insights into how university students value various aspects of the postpaid mobile phone service. Preference-based segmentation is performed on the output from the conjoint analysis to isolate homogeneous consumer segments that possess similar preferences for mobile phone service. Based on the results the study suggests a marketing strategy for mobile phone operators.
Keywords: Conjoint analysis; students' preferences; mobile phone service; postpaid plan; preference-based segmentation
Abstract: Already from the start of the EU ETS, several investigations and analyses have shown that the involved actors are far from treating the emission rights uniformly in their accounting. There is no accepted and uniformly applicable method to determine the exact category and value of these new asset items and to identify how the obligations arising due to the reimbursement of emission rights are to be assessed. At the same time, the various measurement methods may cause significant differences in the profits reported by companies. Therefore, the companies and professional organisations involved in emissions trading are indeed entitled to demand clear guidelines about the accounting treatment of emission rights. The main problem arising in practice is that it is not clarified nor even considered from a theoretical aspect how far the various presentation and measurement methods contribute to the original objective of the emissions trading system, and hence which procedure would represent the most advantageous approach from accounting and social perspectives. The purpose of this research is, through the critical evaluation of the contents of national guidelines issued by professional bodies of European countries and through the review of the impacts of these specifications, to contribute to the creation of a clear and uniformly applicable method in the field of accounting for emission rights. A convergence in accounting for emission rights would be beneficial not only for companies, but also for professional bodies and legislators, independent of which member state are they from.
Keywords: emission rights; EU ETS; accounting; IFRS
Abstract: The technological obsolescence of industrial systems is characterized by the existence of challenger units possessing identical functionalities but with improved performance. This paper aims to define a new approach that makes it possible to obtain the optimal number of obsolete industrial systems which should be replaced by new-type units. This approach presents a new point of view compared with previous works available in the literature. The main idea and the originality of our approach is that we apply a genetic algorithm (GA) by considering the failure frequency, the influence of the environment/safety factors of the old-type systems and the purchase/implementation cost of the new-type units. These parameters are introduced in order to optimize this type of replacement in the context of engineering.
Keywords: technological obsolescence; industrial systems; replacement policy; failure frequency; safety/environment factors; genetic algorithm (GA)
Abstract: The research was aimed at analyzing the polycarbonate scrap arising during production and its possible secondary utilization. The analysis of morphological, rheological and thermal data revealed significant differences between the original pellets and the reground material obtained from injection molded parts. Test specimens were injection molded from various mixtures of the virgin and the reground material, and their mechanical and physical properties were analyzed. Based on the results the reground material may be used in less than 20% proportion, as the mechanical properties of the products do not deviate significantly from those of the products made from virgin polycarbonate.
Keywords: polycarbonates; recycling; mechanical properties; optical properties; morphology
Abstract: It is important to find the shortest path for manoeuvres of UAV, since the power consumed during manoeuvres is tightly coupled with the length of the flight path. In this paper, an algorithm that can find the shortest path during manoeuvres and improve the performance of UAV to follow waypoints is described. The shortest path for UAV during manoeuvres is derived firstly by the theory of Dubins curve. Secondly, in order to improve the ability of UAV to follow the derived optimal path, a real-time path planning algorithm is designed by transforming the constraints of Dubins curve into a dynamic equation. To demonstrate the applicability and performance of the proposed path planning algorithm, two numerical examples are presented. The results show that the proposed algorithm is promising to be applied in the path planning for manoeuvres of UAV.
Keywords: UAV; The shortest path; Path planning algorithm; Dubins curve set