338 research outputs found
Modelling and Simulation of Multi-target Multi-sensor Data Fusion for Trajectory Tracking
An implementation of track fusion using various algorthims has been demonstrated . The sensor measurements of these targets are modelled using Kalman filter (KF) and interacting multiple models (IMM) filter. The joint probabilistic data association filter (JPDAF) and neural network fusion (NNF) algorithms were used for tracking multiple man-euvring targets. Track association and fusion algorithm are executed to get the fused track data for various scenarios, two sensors tracking a single target to three sensors tracking three targets, to evaluate the effects of multiple and dispersed sensors for single target, two targets, and multiple targets. The targets chosen were distantly spaced, closely spaced and crossing. Performance of different filters was compared and fused trajectory is found to be closer to the true target trajectory as compared to that for any of the sensor measurements of that target.Defence Science Journal, 2009, 59(3), pp.205-214, DOI:http://dx.doi.org/10.14429/dsj.59.151
Metallization on FDM Processed Parts Using Electroless Procedure
AbstractMetallization has been studied on flat ABS (acrylonitrile-butadiene-styrene) parts. These parts were fabricated on fused deposition modelling machine using layer by layer deposition principle using ABS as part material. Electroless copper deposition has been performed on these parts using three different surface preparation processes namely aluminium paste (Al paste) coated ABS parts, surface prepared using chromic acid for etching and ABS parts prepared using H2SO4/H2O2 for etching. Surface preparation is followed by Cu (copper) deposition by electroless procedure using four different acidic baths. The acidic baths used are 5 wt% CuSO4 (copper sulphate) with 15 wt% of individual HF (hydrofluoric acid), H2SO4 (sulphuric acid), H3PO4 (phosphoric acid) and CH3COOH (acetic acid) acids. Cu deposition is presented and compared based on their electrical performance, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The results shows that Al pasted samples demonstrated better electrical performance and more uniform Cu deposition
Bond-orientational ordering and shear rigidity in modulated colloidal liquids
From Landau-Alexander-McTague theory and Monte-Carlo simulation results we
show that the modulated liquid obtained by subjecting a colloidal system to a
periodic laser modulation has long range bond-orientational order and non-zero
shear rigidity. From infinite field simulation results we show that in the
modulated liquid phase, the translational order parameter correlation function
decays to zero exponentially while the correlation function for the
bond-orientational order saturates to a finite value at large distances.Comment: 8 pages, elsart documentclass, to be published in Physica A as part
of proceedings for Stat-Phys 3, Calcutt
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for the rapid identification of yeasts causing bloodstream infections
AbstractFew studies have systematically standardised and evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of yeasts from bloodstream infections. This is rapidly becoming pertinent for early identification of yeasts and appropriate antifungal therapy. We used 354 yeast strains identified by polymerase chain reaction (PCR) sequencing for standardisation and 367 blind clinical strains for validation of our MALDI-TOF MS protocols. We also evaluated different sample preparation methods and found the on-plate formic acid extraction method as most cost- and time-efficient. The MALDI-TOF assay correctly identified 98.9% of PCR-sequenced yeasts. Novel main spectrum projections (MSP) were developed for Candida auris, C. viswanathii and Kodamaea ohmeri, which were missing from the Bruker MALDI-TOF MS database. Spectral cut-offs computed by receiver operating characteristics (ROC) analysis showed 99.4% to 100% accuracy at a log score of ≥1.70 for C. tropicalis, C. parapsilosis, C. pelliculosa, C. orthopsilosis, C. albicans, C. rugosa, C. guilliermondii, C. lipolytica, C. metapsilosis, C. nivariensis. The differences in the species-specific scores of our standardisation and blind validation strains were not statistically significant, implying the optimal performance of our test protocol. The MSPs of the three new species also were validated. We conclude that MALDI-TOF MS is a rapid, accurate and reliable tool for identification of bloodstream yeasts. With proper standardisation, validation and regular database expansion, its efficiency can be further enhanced
Imaging in turbid media using quasi-ballistic photons
We study by means of experiments and Monte Carlo simulations, the scattering
of light in random media, to determine the distance upto which photons travel
along almost undeviated paths within a scattering medium, and are therefore
capable of casting a shadow of an opaque inclusion embedded within the medium.
Such photons are isolated by polarisation discrimination wherein the plane of
linear polarisation of the input light is continuously rotated and the
polarisation preserving component of the emerging light is extracted by means
of a Fourier transform. This technique is a software implementation of lock-in
detection. We find that images may be recovered to a depth far in excess of
what is predicted by the diffusion theory of photon propagation. To understand
our experimental results, we perform Monte Carlo simulations to model the
random walk behaviour of the multiply scattered photons. We present a new
definition of a diffusing photon in terms of the memory of its initial
direction of propagation, which we then quantify in terms of an angular
correlation function. This redefinition yields the penetration depth of the
polarisation preserving photons. Based on these results, we have formulated a
model to understand shadow formation in a turbid medium, the predictions of
which are in good agreement with our experimental results.Comment: LaTex 19 pages, 10 ps figures and 8 eps figures. psfig.sty included.
(submitted to Optics Commumications
Optical Limiting in Single-walled Carbon Nanotube Suspensions
Optical limiting behaviour of suspensions of single-walled carbon nanotubes
in water, ethanol and ethylene glycol is reported. Experiments with 532 nm, 15
nsec duration laser pulses show that optical limiting occurs mainly due to
nonlinear scattering. The observed host liquid dependence of optical limiting
in different suspensions suggests that the scattering originates from
microbubbles formed due to absorption-induced heating.Comment: 10 pages, 5 eps figures, to appear in Chem. Phys. Let
Reversible Pressure-Induced Amorphization in Solid C70 : Raman and Photoluminescence Study
We have studied single crystals of by Raman scattering and
photoluminescence in the pressure range from 0 to 31.1 GPa. The Raman spectrum
at 31.1 GPa shows only a broad band similar to that of the amorphous carbon
without any trace of the Raman lines of . After releasing the pressure
from 31.1 GPa, the Raman and the photoluminescence spectra of the recovered
sample are that of the starting crystal. These results indicate that
the molecules are stable upto 31.1 GPa and the amorphous carbon high
pressure phase is reversible, in sharp contrast to the results on solid
. A qualitative explaination is suggested in terms of inter- versus
intra-molecular interactions.Comment: To appear in Phys. Rev. Lett., 12 pages, RevTeX (preprint format), 3
figures available upon reques
Binding of Nucleobases with Single-Walled Carbon Nanotubes
We have calculated the binding energy of various nucleobases (guanine (G),
adenine (A), thymine (T) and cytosine (C)) with (5,5) single-walled carbon
nanotubes (SWNTs) using ab-initio Hartre-Fock method (HF) together with force
field calculations. The gas phase binding energies follow the sequence G A
T C. We show that main contribution to binding energy comes from
van-der Wall (vdW) interaction between nanotube and nucleobases. We compare
these results with the interaction of nucleobases with graphene. We show that
the binding energy of bases with SWNTs is much lower than the graphene but the
sequence remains same. When we include the effect of solvation energy
(Poisson-Boltzman (PB) solver at HF level), the binding energy follow the
sequence G T A C , which explains the experiment\cite{zheng}
that oligonucleotides made of thymine bases are more effective in dispersing
the SWNT in aqueous solution as compared to poly (A) and poly (C). We also
demonstrate experimentally that there is differential binding affinity of
nucleobases with the single-walled carbon nanotubes (SWNTs) by directly
measuring the binding strength using isothermal titration (micro) calorimetry.
The binding sequence of the nucleobases varies as thymine (T) adenine (A)
cytosine (C), in agreement with our calculation.Comment: 7 pages, 6 figure
The STAR Photon Multiplicity Detector
Details concerning the design, fabrication and performance of STAR Photon
Multiplicity Detector (PMD) are presented. The PMD will cover the forward
region, within the pseudorapidity range 2.3--3.5, behind the forward time
projection chamber. It will measure the spatial distribution of photons in
order to study collective flow, fluctuation and chiral symmetry restoration.Comment: 15 pages, including 11 figures; to appear in a special NIM volume
dedicated to the accelerator and detectors at RHI
- …