Electrical Engineering

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The practically important case of a dielectric-loaded tape helix enclosed in a coaxial perfectly conducting cylindrical shell is analysed in this paper. The dielectric-loaded tape helix for guided electromagnetic wave propagation considered here has infinitesimal tape thickness and infinite tape-material conductivity. The homogeneous boundary value problem is solved taking into account the exact boundary conditions similar to the case of anisotropically conducting open tape helix model [1, 2]. The boundary value problem is solved to yield the dispersion equation which takes the form of the solvability condition for an infinite system of linear homogeneous algebraic equations viz., the determinant of the infinite- order coeficient matrix is zero. For the numerical computation of the approximate dispersion characteristic, all the entries of the symmetrically truncated version of the coeficient matrix are estimated by summing an adequate number of the rapidly converging series for them. The tape-current distribution is estimated from the null-space vector of the truncated coeficient matrix corresponding to a specified root of the dispersion equation.

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Fulltext

Progress In Electromagnetics Research B

Propagation of electromagnetic waves guided by the anisotropically conducting model of a tape helix supported by dielec- tric rods

In this paper, we propose a novel feature representation for binary patterns by exploiting the object shape information. Initial evaluation of the representation is performed for Bengali and Gujarati script character classification. The extension of the representation for word images is presented subsequently. The proposed feature representation in combination with distance-based hashing is applied for defining novel word image-based document image indexing and retrieval framework. The concept of hierarchical hashing is utilized to reduce the retrieval time complexity. In addition, with the objective of reduction in the size of hashing data structure, the concept of multi-probe hashing is extended for binary mapping functions. The exhaustive experimental evaluation of the proposed framework on a collection of documents belonging to Devanagari, Bengali and English scripts has yielded encouraging results. © 2012 Springer-Verlag.

International Journal on Document Analysis and Recognition

Word shape descriptor-based document image indexing: A new DBH-based approach

The design, synthesis and characterization of five diphenylhydrazone end capped molecules as donors for Bulk Heterojunction (BHJ) solar cells are described. The use of the hydrazone donor instead of the more common amine one is advantageous in terms of synthetic access and overall stability. We show that the variation of both the nature and the substitution pattern of the electron deficient conjugated bridge enables the tuning of the optical energy gap as well as of the HOMO and LUMO. In particular, our data show that the low energy shift of the HOMO level along the series of hydrazone compounds, one of the critical parameters affecting the performance of BHJ cells, is as high as 0.42 eV. We tested all derivatives as donors in a BHJ configuration, using the fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. We found that the trend we observed in the progressive stabilization of the chromophore HOMO level upon increasing the electron accepting capabilities of the conjugated bridge is reflected in the progressive increase of the cell open circuit voltage (Voc). Our preliminary results show that it is possible to obtain a Vocas high as 0.74 V, along with a power conversion efficiency of 1.2%. © 2013 The Royal Society of Chemistry.

Journal of Materials Chemistry A

Open circuit voltage tuning through molecular design in hydrazone end capped donors for bulk heterojunction solar cells

In this paper a Fast Array Multichannel Two-Dimensional Recursive Least Square (FAM 2D-RLS) adaptive filter is proposed for estimating an OFDM channel in frequency domain. This filter makes use of the shift structure of the input data vector. Thus the computational cost of the classical RLS filter which is O(M 2) is reduced to O(M) for each iteration where M is the order of the filter. In order to ensure numerical stability in finite precision, we make use of array-based methods for implementing FAM 2D-RLS. The adaptive filters illustrated in the standard literature consist of a weight vector and desired data as a scalar. But in our scenario of OFDM channel estimation the weight is a matrix while the desired data are a vector. Hence the algorithm for the matrix form of FAM-2D RLS and its steady state equations are derived. Numerical stability, steady state and convergence performance are verified using MATLAB simulations. © 2012 Springer Science+Business Media New York.

Circuits, Systems, and Signal Processing

Fast array multichannel 2D-RLS based OFDM channel estimator

With the development of high resolution infrared cameras, thermography is gaining increased attention of the researcher not merely as a non-contact tool to measure surface temperature of the objects, but also as a tool in fine physical experiments to analyze thermo-physical phenomena. Apart from their regular application in condition monitoring and preventive maintenance, the infrared cameras are slowly finding application in research and development. In the field of textile research, the application of thermal imaging is still at its infancy. Most of the present applications are for qualitative observations of surface temperature profile of the object. In the present paper, various applications of thermography in textiles and allied fields have been reported with a projection of potential future research where thermography may play crucial roles.

Indian Journal of Fibre and Textile Research

Infrared thermography in material research - A review of textile applications

Lock-in thermography is increasingly becoming popular as a non-destructive testing technique for defect detection in composite materials for its low heating excitation. The experimental data is processed with Fourier transformation to produce phase and amplitude images. Phase images, though immune to surface emissivity variation, suffer from blind frequency effect, where a defect becomes invisible at a certain excitation frequency. There exists no analytical model to predict this 3-dimensional heat flow phenomenon. This paper presents a study of blind frequency using electro-thermal model based numerical simulation on a piece of thermally anisotropic carbon fibre composite. The performance of the simulator is optimized for spatial mesh size. Further the effect of paint layer, which is often applied to the sample surface for better thermal imaging, has been incorporated in the simulation. Finally, both experimental and simulation results are presented side-by-side for easy comparison. © 2013 AIP Publishing LLC.

Journal of Applied Physics

Prediction of blind frequency in lock-in thermography using electro-thermal model based numerical simulation

Abstract Electron transport studies in Tris(8-hydroxyquinolinato) aluminum (Alq3) is hindered due to lack of efficient electron injecting electrode. We demonstrate that an electron injection layer of Cs 2CO3 forms ohmic contact with Alq3, which enables the observation of SCLC. This allows us to directly determine the electron mobility in Alq3, which was found to be 1 × 10 -9 m2/V s at room temperature. Doping of Cs 2CO3 leads to increase in conductivity as well as mobility. Mobility has increased to 1 × 10-7 m2/V s for 33% doping of Cs2CO3.© 2013 Elsevier B.V. All rights reserved.

Organic Electronics

Effect of doping of cesium carbonate on electron transport in Tris(8-hydroxyquinolinato) aluminum

We consider a distributed MAC setting with block-wise flat fading links and full receiver CSI (channel state information). Of the L transmitters, a subset is assumed to have knowledge of the global CSI vector in each block, whereas the remaining users have access only to their respective link qualities, i.e. each one in the latter set is unaware of the quality of other links. Outage is not allowed in any communication block. We propose efficient power-allocation and rate-adaptation strategies which are sum-rate optimal when users in each subset observe identical fading distributions chosen from a class, which includes the popular Rayleigh, Ricean etc. {\textcopyright} 2013 IEEE.

IEEE International Symposium on Information Theory - Proceedings

On fading MAC channels with asymmetric CSI

A new modelling method of image jacobian estimation is presented for uncalibrated visual servoing of robots, in which a kernel recursive least squares (KRLS) technique is used for non-linear mapping between target image features and robot joint angles, and an image jacobian expression is derived from the KRLS algorithm with gaussian kernel. The simulations of robot visual servoing with eye-in-hand camera configuration are conducted using the KRLS jacobian estimator and the same are compared with SVR and LS-SVM jacobian estimators. The simulation results have shown that the robot visual servoing converges at the desired goal and KRLS is proved to be a better choice. © 2013 IEEE.

IEEE International Symposium on Intelligent Control - Proceedings

Kernel machines for uncalibrated visual servoing of robots

The paper proposes a novel multi-modal document image retrieval framework by exploiting the information of text and graphics regions. The framework applies multiple kernel learning based hashing formulation for generation of composite document indexes using different modalities. The existing multimedia management methods for imaged text documents have not addressed the requirement of old and degraded documents. In the subsequent contribution, we propose novel multi-modal document indexing framework for retrieval of old and degraded text documents by combining OCR'ed text and image based representation using learning. The evaluation of proposed concepts is demonstrated on sampled magazine cover pages, and documents of Devanagari script. © 2013 IEEE.