Department of Electrical Engineering

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IIT Jodhpur

We propose a new non-intrusive speech quality assessment algorithm based on Support Vector Regression (SVR) and Mel Frequency Cepstral Coefficients (MFCCs). The basic idea is to map the MFCCs into the desired quality score using SVR. The sensitivity of the MFCCs to external noise is exploited to gauge the changes in the speech signal to evaluate its perceptual quality. The use of SVR exploits the advantages of machine learning with the ability to learn complex data patterns for an effective and generalized mapping of features into a perceptual score, in contrast with the oft-utilized feature pooling process in the existing speech quality estimators. Experimental results indicate that the proposed approach outperforms the standard P.563 algorithm for non-intrusive assessment of speech quality with a total of 1792 speech files and the associated subjective scores. © 2010 Springer-Verlag Berlin Heidelberg.

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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Non-intrusive speech quality assessment with support vector regression

Image quality assessment is useful in many visual processing systems and a great deal of research effort has been put in during the recent years to develop objective image quality metrics that correlate well with the perceived quality measurement. Assessing visual quality of images is not easy since the Human Visual System (HVS) is complicated and difficult to be modelled. It is well known that the HVS is sensitive to spatial frequencies and structure in images, so accounting for structure degradation in images is essential for effective picture quality prediction. In this paper, we propose the use of singular vectors out of Singular Value Decomposition as effective structuring elements in images and use them to quantify the loss in structural information in images. The scalability of the proposed metric has been also explored since singular vectors are ordered according to their visual significance. The proposed metric has been validated convincingly on three independent databases (a total of 1196 images of different distortion types and extents), and found to outperform the relevant existing image quality metrics in literature with all circumstances. © 2009 IEEE.

2009 IEEE International Workshop on Multimedia Signal Processing, MMSP '09

Scalable image quality assessment based on structural vectors

A method to design a high performance robust tracking controller to track step references for uncertain continuous MIMO plant is presented. A non-linear sliding surface is proposed by which the damping ratio of closed loop system is increased as output approaches setpoint. Stability with the proposed non-linear surface is proved. A new control law is designed to guarantee the existence of sliding mode around the proposed non-linear surface. Position controller of stepper is designed using the proposed algorithm and corresponding simulation results are presented to show the effectiveness of the proposed scheme.

Proceedings of the IEEE International Conference on Industrial Technology

A robust tracking controller for uncertain MIMO plant using non-linear sliding surface

Low-voltage pentacene organic field-effect transistors (OFETs) with different gate dielectric interfaces are studied and their performance in terms of electrical properties and operational stability is compared. Overall high electrical performance is demonstrated at low voltage by using a 100 nm-thick high-κ gate dielectric layer of aluminum oxide (Al2O3) fabricated by atomic layer deposition (ALD) and modified with hydroxyl-free low-κ polymers like polystyrene (PS), divinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB) (Cyclotene™, Dow Chemicals), and as well as with the widely used octadecyl-trichlorosilane (OTS). Devices with PS and BCB dielectric surfaces exhibit almost similar electrical performance with high field-effect mobilities, low subthreshold voltages, and high on/off current ratios. The higher mobility in pentacene transistors with PS can be correlated to the better structural ordering of pentacene films, as demonstrated by atomic force microscopy (AFM) images and X-ray diffraction (XRD). The devices with PS show good electrical stability under bias stress conditions (VGS = VDS = -10 V for 1 h), resulting in a negligible drop (∼2%) in saturation current (IDS) in comparison to that in devices with OTS (∼12%), and to a very high decay (∼30%) for the devices with BCB. © 2009 Elsevier B.V. All rights reserved.

Organic Electronics

Pentacene organic field-effect transistors with polymeric dielectric interfaces: Performance and stability

Underactuated systems are the representative of a large class of systems. This paper presents a new method for the design of sliding surface for a class of second order underactuated system in which a virtual input is considered in unactuated subsystem. A sliding mode controller is proposed to ensure sliding along the sliding surface. A problem of slosh free-motion of a container is considered as representative of a typical class of underactuated system. A simple pendulum model is considered to represent the lateral slosh. Extensive simulation studies are conducted with the controller to demonstrate the proposed approach. © 2009 Inderscience Enterprises Ltd.

International Journal of Advanced Mechatronic Systems

Sliding mode control for slosh-free motion-A class of underactuated system

In this paper, the modeling and design of a multirate output feedback based discrete sliding mode control scheme application for the vibration control of a smart flexible Timoshenko cantilever beam for a single input single output (SISO) case by retaining the first two dominant vibratory modes is presented. In our work, the effect of shear and axial displacement has been considered. The algorithm uses a fast output sampling based sliding mode control strategy that would avoid the use of switching in the control input and hence avoids chattering. This method does not need the measurement of the system states for feedback as it makes use of only the output samples for designing the controller. Thus, this methodology is more practical and easy to implement. Piezoelectric patches are bonded as sensor/actuator to the master structure at different locations along the length of the beam. The beam structure is modeled in the state space form using the concept of piezoelectric theory, the Timoshenko beam theory and the FEM technique and by dividing the beam into four finite elements and placing the piezoelectric sensor/actuator at one location as a collocated pair at a time, i.e., as surface mounted sensor/actuator, say, at finite element position 1 or 2 or 3 or 4, thus giving rise to four SISO models of the same smart structure plant. Controllers are designed for the above four models of the same plant by retaining the first two dominant vibratory modes. The performance of the smart system for higher modes (say three vibratory modes) is also investigated. The piezo sensor/actuator pair is moved from the free end to the fixed end of the beam. The effect of placing the sensor/actuator at various locations along the length of the beam is observed and the conclusions are drawn for the best performance (best model) and for the smallest magnitude of the control input required to control the vibrations of the smart flexible beam. © 2009 Elsevier Ltd. All rights reserved.

Journal of Sound and Vibration

Vibration control of Timoshenko smart structures using multirate output feedback based discrete sliding mode control for SISO systems

In this paper, we present a method combining surface-enhanced Raman scattering (SERS) spectroscopy to detect biomolecules in a label-free way with an electrokinetic preconcentration technique (electrophoresis) to amplify biomolecular signals at low concentrations. A constant electric field is applied to charged biomolecules in solution, attracting them to an oppositely charged electrode, which is also used as a SERS substrate. Within 5 min, we observed that the SERS signal of 10 fM adenine was amplified to the level of the signal of non-preconcentrated 1 μM adenine (sensitivity improvement by 8 orders of magnitude) and the method was effective over a wide range of concentrations (10 fM to 1 μM). The signals were further amplified under stronger electric field and longer application: The increase of the signal intensity was observed to be 51 times at -0.6 V cm-1 after 25 min. The effectiveness of this method allows the creation of label-free, target-specific, and highly sensitive monitoring applications. © 2009 The Royal Society of Chemistry.

Lab on a Chip

Label-free and highly sensitive biomolecular detection using SERS and electrokinetic preconcentration

This paper presents a new approach to design a sliding mode controller for a class of mismatched uncertain systems. A method is proposed for the design of a switching surface in the presence of mismatched uncertainties. A design method for a sliding mode observer based on high gain is also proposed in this paper to reconstruct the states of the system for the implementation of sliding mode control. The design technique is simple and computationally efficient. A control problem for the slosh-free motion of a container is considered as the representative of a typical class of systems. A simple pendulum model is considered to represent the lateral slosh. The validity of the proposed scheme is demonstrated by simulation along with the experimental results. © 2009 IEEE.

IEEE Transactions on Industrial Electronics

Sliding mode observer based sliding mode controller for slosh-free motion through PID scheme

This paper presents the design and experimental implementation of a simultaneous periodic output feedback controller to minimize structural vibration using collocated piezoelectric actuator and sensor. The linear dynamic model of piezoelectric-bonded cantilever beams is obtained using online recursive leastsquare parameter estimation. A digital control system that consists of simulink modelling software and dSPACE 1104 controller board is used for identification and control. The performance of simultaneous controller is evaluated by considering a cantilever beam structure of three different lengths and mass. The effectiveness of the controller is demonstrated experimentally by exciting the structures at resonance. The advantage of the simultaneous periodic output feedback controller implemented in this paper is unique in the sense that the common controller gain reduces the first two vibration modes of three plants, which is not commonly shown in the literature with other feedback controllers. From the experimental results it is observed that with the simultaneous output feedback controller the vibration reduction is approximately 75% for the first mode and 60% for the second mode for all the three plants. © 2008 John Wiley & Sons, Ltd.

Structural Control and Health Monitoring

Design and experimental evaluation of simultaneous periodic output feedback control for piezoelectric actuated beam structure

In this paper, a method is presented for frequency-shaped sliding mode control using output feedback. A compensator is introduced in the sliding surface to attenuate the certain frequency component of the sliding mode dynamics. The output is measured at a faster rate than the control input to estimate the states of the system. The proposed output feedback frequency-shaped sliding mode controller is designed for the vibration suppression of intelligent structure. The simulation and experimental results show the efficacy of the method. © 2009 IEEE