The onset of oscillatory Marangoni convection in a two-layer system of conducting fluid in the presence of a uniform magnetic field

A combination of numerical and analytical techniques is used to analyse the effect of magnetic field and encapsulated layer on the onset of oscillatory Marangoni instability in a two layer system. Oscillatory Marangoni instability is possible for a deformed free surface only when the system is heated from above. It is observed that the existence of a second layer has a positive effect on Marangoni overstability with magnetic field whereas it has an opposite effect without magnetic field.

Limit Laws for Coverage in Backbone-Sensor Networks

We study the coverage in sensor networks having two types of nodes, sensor and backbone nodes. Each sensor is capable of transmitting information over relatively small distances. The backbone nodes collect information from the sensors. This information is processed and communicated over an ad-hoc network formed by the backbone nodes,which are capable of transmitting over much larger distances. We consider two modes of deployment of sensors, one a Poisson-Poisson cluster model and the other a dependently-thinned Poisson point process. We deduce limit laws for functionals of vacancy in both models using properties of association for random measures.

Bounds on Defect Level and Fault Coverage in Linear Analog Circuit Testing

Transfer function coefficients (TFC) are widely used to test linear analog circuits for parametric and catastrophic faults. This paper presents closed form expressions for an upper bound on the defect level (DL) and a lower bound on fault coverage (FC) achievable in TFC based test method. The computed bounds have been tested and validated on several benchmark circuits. Further, application of these bounds to scalable RC ladder networks reveal a number of interesting characteristics. The approach adopted here is general and can be extended to find bounds of DL and FC of other parametric test methods for linear and non-linear circuits.

Analysis of non-uniform waveguide in MZI and optimization of the power confinement in the waveguide

The technological world has attained a new dimension with the advent of miniaturization and a major breakthrough has evolved in the form of moems, technically more advanced than mems. This breakthrough has paved way for the scientists to research and conceive their innovation. This paper presents a mathematical analysis of the wave propagation along the non-uniform waveguide with refractive index varying along the z axis implemented on the cantilever beam of MZI based moem accelerometer. Secondly the studies on the wave bends with minimum power loss focusing on two main aspects of bend angle and curvature angle is also presented.

Supercapacitor studies on globular polypyrrole microstructures developed by a facile electrochemical route

Micrometre-scale polypyrrole (PPy) structures are synthesised for electrochemical supercapacitor applications by a facile electrochemical route. Globular polypyrrole microstructures of size < 5 μm are grown on stainless steel (SS-304) substrate by electro-polymerisation of pyrrole on oxygen microbubble templates electrochemically generated and stabilised in the presence of surfactant/supporting electrolyte/ dopant b-naphthalene sulfonic acid (b-NSA). Microstructures obtained with scan range of 0??1.6 V (against Ag/AgCl) are uniformly distributed over the surface with high coverage density of 5 x 105 to 8 x 10 cm-2. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the formed microstructures are of Β-NSA doped PPy. Scanning electron microscopy showed the uniform spread and good coverage of microstructures over the substrate. Supercapacitor properties of PPy films are investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge methods with 1.0 M KCl as electrolyte in a three-electrode electrochemical cell. Specific capacitance of 583 Fg-1 is obtained, which is greater than the values (350-400 Fg-1 highest) usually reported for this material. Electrochemical impedance spectroscopy proves the superc

Supercapacitor studies on globular polypyrrole microstructures developed by a facile electrochemical route

Micrometre-scale polypyrrole (PPy) structures are synthesised for electrochemical supercapacitor applications by a facile electrochemical route. Globular polypyrrole microstructures of size <5 mu m are grown on stainless steel (SS-304) substrate by electro-polymerisation of pyrrole on oxygen microbubble templates electrochemically generated and stabilised in the presence of surfactant/supporting electrolyte/dopant beta-naphthalene sulfonic acid (beta-NSA). Microstructures obtained with scan range of 0-1.6 V (against Ag/AgCl) are uniformly distributed over the surface with high coverage density of 5 x 10(5) to 8 x 10 cm(-2). Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the formed microstructures are of beta-NSA doped PPy. Scanning electron microscopy showed the uniform spread and good coverage of microstructures over the substrate. Supercapacitor properties of PPy films are investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge methods with 1.0 M KCl as electrolyte in a three-electrode electrochemical cell. Specific capacitance of 583 Fg(-1) is obtained, which is greater than the values (350-400 Fg(-1) highest) usually reported for this material. Electrochemical impedance spectroscopy proves the supercapacitance behaviour and explains the special inductive component of impedance observed in the high-frequency regime because of the globular structures of PPy deposited

SPARSE SIGNAL RECONSTRUCTION BASED ON SIGNAL DEPENDENT NON-UNIFORM SAMPLES

The classical approach to A/D conversion has been uniform sampling and we get perfect reconstruction for bandlimited signals by satisfying the Nyquist Sampling Theorem. We propose a non-uniform sampling scheme based on level crossing (LC) time information. We show stable reconstruction of bandpass signals with correct scale factor and hence a unique reconstruction from only the non-uniform time information. For reconstruction from the level crossings we make use of the sparse reconstruction based optimization by constraining the bandpass signal to be sparse in its frequency content. While overdetermined system of equations is resorted to in the literature we use an undetermined approach along with sparse reconstruction formulation. We could get a reconstruction SNR > 20dB and perfect support recovery with probability close to 1, in noise-less case and with lower probability in the noisy case. Random picking of LC from different levels over the same limited signal duration and for the same length of information, is seen to be advantageous for reconstruction.

Improved Detection of Remote Homologues Using Cascade PSI-BLAST: Influence of Neighbouring Protein Families on Sequence Coverage

Background: Development of sensitive sequence search procedures for the detection of distant relationships between proteins at superfamily/fold level is still a big challenge. The intermediate sequence search approach is the most frequently employed manner of identifying remote homologues effectively. In this study, examination of serine proteases of prolyl oligopeptidase, rhomboid and subtilisin protein families were carried out using plant serine proteases as queries from two genomes including A. thaliana and O. sativa and 13 other families of unrelated folds to identify the distant homologues which could not be obtained using PSI-BLAST. Methodology/Principal Findings: We have proposed to start with multiple queries of classical serine protease members to identify remote homologues in families, using a rigorous approach like Cascade PSI-BLAST. We found that classical sequence based approaches, like PSI-BLAST, showed very low sequence coverage in identifying plant serine proteases. The algorithm was applied on enriched sequence database of homologous domains and we obtained overall average coverage of 88% at family, 77% at superfamily or fold level along with specificity of similar to 100% and Mathew's correlation coefficient of 0.91. Similar approach was also implemented on 13 other protein families representing every structural class in SCOP database. Further investigation with statistical tests, like jackknifing, helped us to better understand the influence of neighbouring protein families. Conclusions/Significance: Our study suggests that employment of multiple queries of a family for the Cascade PSI-BLAST searches is useful for predicting distant relationships effectively even at superfamily level. We have proposed a generalized strategy to cover all the distant members of a particular family using multiple query sequences. Our findings reveal that prior selection of sequences as query and the presence of neighbouring families can be important for covering the search space effectively in minimal computational time. This study also provides an understanding of the `bridging' role of related families.

Limit laws for coverage in backbone-sensor networks

We study coverage in sensor networks having two types of nodes, namely, sensor nodes and backbone nodes. Each sensor is capable of transmitting information over relatively small distances. The backbone nodes collect information from the sensors. This information is processed and communicated over an ad hoc network formed by the backbone nodes, which are capable of transmitting over much larger distances. We consider two models of deployment for the sensor and backbone nodes. One is a PoissonPoisson cluster model and the other a dependently thinned Poisson point process. We deduce limit laws for functionals of vacancy in both models using properties of association for random measures.

Non-rotating beams isospectral to a given rotating uniform beam

In this paper, we seek to find non-rotating beams with continuous mass and flexural stiffness distributions, that are isospectral to a given uniform rotating beam. The Barcilon-Gottlieb transformation is used to convert the fourth order governing equation of a non-rotating beam, to a canonical fourth order eigenvalue problem. If the coefficients in this canonical equation match with the coefficients of the uniform rotating beam equation, then the non-rotating beam is isospectral to the given rotating beam. The conditions on matching the coefficients leads to a pair of coupled differential equations. We solve these coupled differential equations for a particular case, and thereby obtain a class of non-rotating beams that are isospectral to a uniform rotating beam. However, to obtain isospectral beams, the transformation must leave the boundary conditions invariant. We show that the clamped end boundary condition is always invariant, and for the free end boundary condition to be invariant, we impose certain conditions on the beam characteristics. We also verify numerically that the frequencies of the non-rotating beam obtained using the finite element method (FEM) are the exact frequencies of the uniform rotating beam. Finally, the example of beams having a rectangular cross-section is presented to show the application of our analysis. Since experimental determination of rotating beam frequencies is a difficult task, experiments can be easily conducted on these rectangular non-rotating beams, to calculate the frequencies of the rotating beam. (c) 2012 Elsevier Ltd. All rights reserved.

Rotating beams isospectral to axially loaded nonrotating uniform beams

In this paper, the stiffness and mass per unit length distributions of a rotating beam, which is isospectral to a given uniform axially loaded nonrotating beam, are determined analytically. The Barcilon-Gottlieb transformation is extended so that it transforms the governing equation of a rotating beam into the governing equation of a uniform, axially loaded nonrotating beam. Analysis is limited to a certain class of Euler-Bernoulli cantilever beams, where the product between the stiffness and the cube of mass per unit length is a constant. The derived mass and stiffness distributions of the rotating beam are used in a finite element analysis to confirm the frequency equivalence of the given and derived beams. Examples of physically realizable beams that have a rectangular cross section are shown as a practical application of the analysis.