Novel approach for simultaneous measurement of strain and temperature using a single tapered fiber Bragg grating

A novel approach for simultaneous measurement of strain and temperature with a single tapered fiber Bragg grating is proposed. This method is based on the fact that the reflectivity at central wavelength of FBG reflection changes with chirp (strain gradient). A diode laser is locked to the central wavelength of FBG reflection. Central wavelength of the FBG shifts with temperature. Change in reflectivity & wavelength of the diode laser were used to measure strain and temperature on the FBG respectively.

Simultaneous measurement of strain and temperature with a pair of matched fiber Bragg gratings

A novel approach for simultaneous measurement of static/dynamic strain and temperature with a pair of matched fiber Bragg grating(FBG)s is proposed. When a diode laser locked to the mid reflection frequency of reference FBG is used to illuminate the sensor FBG, reflected intensity changes with strain on sensor FBG. Reference FBG responds with temperature on sensor FBG and is immune to strain, hence, wavelength of the diode laser acts as a signature for temperature measurement. Theoretical sensitivity limit for static strain and temperature are 1.2n epsilon / root Hz and 0.0011 degrees C respectively. Proposed sensor shows a great potential in high sensitive strain measurements with a simplified experimental setup.

Simultaneous measurement of multiple parameters using a single fiber Bragg grating

A novel approach for simultaneous measurement of chirp (any parameter that can induce strain gradient on FBG) and temperature using a single FBG is proposed. Change in reflectivity at central wavelength of FBG reflection & Bragg wavelength shifts induced due to temperature were used for chirp & temperature measurements respectively. Theoretical resolution limit for chirp and temperature using an Optical Spectrum Analyzer (OSA) with 1pm wavelength resolution and >58dB dynamic range are 12.8fm and 1/13 degrees C respectively.

WebGeSTer DB-a transcription terminator database

We present WebGeSTer DB, the largest database of intrinsic transcription terminators (http://pallab.serc.iisc.ernet.in/gester). The database comprises of a million terminators identified in 1060 bacterial genome sequences and 798 plasmids. Users can obtain both graphic and tabular results on putative terminators based on default or user-defined parameters. The results are arranged in different tiers to facilitate retrieval, as per the specific requirements. An interactive map has been incorporated to visualize the distribution of terminators across the whole genome. Analysis of the results, both at the whole-genome level and with respect to terminators downstream of specific genes, offers insight into the prevalence of canonical and non-canonical terminators across different phyla. The data in the database reinforce the paradigm that intrinsic termination is a conserved and efficient regulatory mechanism in bacteria. Our database is freely accessible.

A Non-contact measurement technique to measure micro surface stress and obtain deformation profiles of the order of 1nm in Micro-cantilever based structures by single image Optical Diffraction method

A new method based on analysis of a single diffraction pattern is proposed to measure deflections in micro-cantilever (MC) based sensor probes, achieving typical deflection resolutions of 1nm and surface stress changes of 50 mu N/m. The proposed method employs a double MC structure where the deflection of one of the micro-cantilevers relative to the other due to surface stress changes results in a linear shift of intensity maxima of the Fraunhofer diffraction pattern of the transilluminated MC. Measurement of such shifts in the intensity maxima of a particular order along the length of the structure can be done to an accuracy of 0.01mm leading to the proposed sensitivity of deflection measurement in a typical microcantilever. This method can overcome the fundamental measurement sensitivity limit set by diffraction and pointing stability of laser beam in the widely used Optical Beam Deflection method (OBDM).

Measurement of complex optical flow with use of an augmented generalized gradient scheme

We present a method for measuring the local velocities and first-order variations in velocities in a timevarying image. The scheme is an extension of the generalized gradient model that encompasses the local variation of velocity within a local patch of the image. Motion within a patch is analyzed in parallel by 42 different spatiotemporal filters derived from 6 linearly independent spatiotemporal kernels. No constraints are imposed on the image structure, and there is no need for smoothness constraints on the velocity field. The aperture problem does not arise so long as there is some two-dimensional structure in the patch being analyzed. Among the advantages of the scheme is that there is no requirement to calculate second or higher derivatives of the image function. This makes the scheme robust in the presence of noise. The spatiotemporal kernels are of simple form, involving Gaussian functions, and are biologically plausible receptive fields. The validity of the scheme is demonstrated by application to both synthetic and real video images sequences and by direct comparison with another recently published scheme Biol. Cybern. 63, 185 (1990)] for the measurement of complex optical flow.

Fuel drop size measurement in a carburetted induction system with 2 throttling methods

A new throttling system far SI engines is examined. The SMD of the fuel droplets in the induction system is measured to evaluate the performance of the new device with respect to the conventional throttle plate arrangement. The measurements are conducted at steady now conditions. A forward angular scattering technique with a He-Ne laser beam is used for droplet size measurement. The experiments are carried out with different mixture strength, stream velocity and throttle positions. It is observed that A/F ratio has no effect on SMD. However, stream velocity and throttle position have a significant influence on SMD. The new throttling method is found to be more effective in reducing the SMD, particularly at low throttle opening and high stream velocity compared to the conventional throttle plate.

Measurement of complex optical flow with use of an augmented generalized gradient scheme

We present a method for measuring the local velocities and first-order variations in velocities in a time-varying image. The scheme is an extension of the generalized gradient model that encompasses the local variation of velocity within a local patch of the image. Motion within a patch is analyzed in parallel by 42 different spatiotemporal filters derived from 6 linearly independent spatiotemporal kernels. No constraints are imposed on the image structure, and there is no need for smoothness constraints on the velocity field. The aperture problem does not arise so long as there is some two-dimensional structure in the patch being analyzed. Among the advantages of the scheme is that there is no requirement to calculate second or higher derivatives of the image function. This makes the scheme robust in the presence of noise. The spatiotemporal kernels are of simple form, involving Gaussian functions, and are biologically plausible receptive fields. The validity of the scheme is demonstrated by application to both synthetic and real video images sequences and by direct comparison with another recently published scheme [Biol. Cybern. 63, 185 (1990)] for the measurement of complex optical flow.

Sputtered thin-film strain gauges for differential pressure measurement

A differential pressure transducer with sputtered gold films as strain gauges has been designed and fabricated. The construction details of the sensing element assembly are given. The details of the strain gauge film configuration employed and the thin-film deposition process are also presented. Information on the output characteristics of the differential pressure transducer such as effect of pressure cycles on output, thermal stability, bidirectional calibration results obtained and individual gauge stability is reported.

Application of selective F-1 decoupled H-1 NMR for enantiomer resolution and accurate measurement of enantiomeric excess at low chiral substrate/auxiliary concentration

The higher substrate and chiral auxiliary concentration is a pre-requisite to obtain efficient separation of H-1 NMR signals of enantiomers. The higher concentration of chiral lanthanide shift reagents provides broadened spectral lines resulting in a severe loss of resolution between the enantiomer resonances. In order to circumvent such difficulties, herein we present the application and the usefulness of a selective F-1 decoupled correlation (COSY) experiment which yields proton decoupled proton spectra in the indirect dimension. The potentiality of the experiment is demonstrated on several chiral compounds possessing different functional groups, employing either a lanthanide shift reagent or a solvating reagent as chiral auxiliaries. (C) 2011 Elsevier B.V. All rights reserved.

Evaluation of strain-rate effects in transitional round jets using direct numerical simulation

The coherent flame model uses the strain rate to predict reaction rate per unit flame surface area and some procedure that solves for the dynamics of flame surfaces to predict species distributions. The strainrate formula for the reaction rate is obtained from the analytical solution for a flame in a laminar, plane stagnation point flow. Here, the formula's effectiveness is examined by comparisons with data from a direct numerical simulation (DNS) of a round jetlike flow that undergoes transition to turbulence. Significant differences due to general flow features can be understood qualitatively: Model predictions are good in the braids between vortex rings, which are present in the near field of round jets, as the strain rate is extensional and reaction surfaces are isolated. In several other regions, the strain rate is compressive or flame surfaces are folded close together. There, the predictions are poor as the local flow no longer resembles the model flow. Quantitative comparisons showed some discrepancies. A modified, consistent application of the strain-rate solution did not show significant changes in the prediction of mean reaction rate distributions.

Spin-Selective Correlation Experiment for Measurement of Long-Range J Couplings and for Assignment of (R/S) Enantiomers from the Residual Dipolar Couplings and DFT

We report the C-HETSERF experiment for determination of long- and short-range homo- and heteronuclear scalar couplings ((n)J(HH) and (n)J(XH), n >= 1) of organic molecules with a low sensitivity dilute heteronucleus in natural abundance. The method finds significant advantage in measurement of relative signs of long-range heteronuclear total couplings in chiral organic liquid crystal. The advantage of the method is demonstrated for the measurement of residual dipolar couplings (RDCs) in enantiomers oriented in the chiral liquid crystal with a focus to unambiguously assign R/S designation in a 2D spectrum. The alignment tensor calculated from the experimental RDCs and with the computed structures of enantiomers obtained by DFT calculations provides the size of the back-calculated RDCs. Smaller root-mean-square deviations (rmsd) between experimental and calculated RDCs indicate better agreement with the input structure and its correct designation of the stereogenic center.

RPS: Repeats in Protein Sequences

Repeats are two or more contiguous segments of amino acid residues that are believed to have arisen as a result of intragenic duplication, recombination and mutation events. These repeats can be utilized for protein structure prediction and can provide insights into the protein evolution and phylogenetic relationship. Therefore, to aid structural biologists and phylogeneticists in their research, a computing resource (a web server and a database), Repeats in Protein Sequences (RPS), has been created. Using RPS, users can obtain useful information regarding identical, similar and distant repeats (of varying lengths) in protein sequences. In addition, users can check the frequency of occurrence of the repeats in sequence databases such as the Genome Database, PIR and SWISS-PROT and among the protein sequences available in the Protein Data Bank archive. Furthermore, users can view the three-dimensional structure of the repeats using the Java visualization plug-in Jmol. The proposed computing resource can be accessed over the World Wide Web at http://bioserver1.physics.iisc.ernet.in/rps/.

Measurement of Gibbs energy of formation of Ca2PbO4 using a solid-state cell with three electrodes

Phase relations in the system Ca-Pb-O at 1100 K have been determined by equilibrating 18 compositions in the ternary and identifying the phases present in quenched samples by X-ray diffraction and energy dispersive X-ray analysis (EDX). Only one ternary compound Ca2PbO4 was found to be present. The compound coexists with CaO and PbO. The intermetallic compounds Ca2Pb, Ca5Pb3 and CaPb and liquid alloys are in equilibrium with CaO. The standard Gibbs energies of formation of Ca2PbO4 (880 - 1100 K) and Pb3O4 (770 - 910 K) were determined using solid-state cells based on yttria-stabilized zirconia as the solid electrolyte. Pure oxygen gas at 0.1 MPa was used as the reference electrode. For measurements on Ca2PbO4, a novel cell design with three electrodes in series, separated by solid electrolyte membranes, was used to avoid polarization of the electrode containing three solid phases. Two three-phase electrodes were used. The first absorbs the electrochemical flux of oxygen from the reference electrode to the measuring electrode. The other three-phase electrode, which is unaffected by the oxygen flux through the solid electrolyte, is used for electromotive force (EMF) measurement. The results from EMF studies were cross-checked using thermogravimetry (TG) under controlled oxygen partial pressures. The stability of Pb3O4 was investigated using a conventional solid-state cell with RuO2 electrodes. The results can be summarized by the following equations: 2CaO + PbO +1/2O(2) --> Ca2PbO4 Delta(r)G degrees/J mol(-1) = (- 128340 + 93.21 T/K) +/- 200 3PbO + 1/2O(2) --> Pb3O4 Delta(r)G degrees/J mol(-1) = (- 70060 + 77.5 T/K) +/- 150

Method for measurement of the angles of 90-, 45-, 45-deg and 60-, 30-, 90-deg prisms

A simple technique is devised to measure the angles of 90-, 45-, 45-deg and 60-, 30-, 90-deg prisms without using expensive spectrometers, autocollimators, and angle gauges. The method can be extended to unpolished and opaque prisms made of materials other then glass. (C) 1997 Society of Photo-Optical instrumentation Engineers.