Data fusion with Gaussian processes

This paper addresses the problem of fusing multiple sets of heterogeneous sensor data using Gaussian processes (GPs). Experiments on large scale terrain modeling in mining automation are presented. Three techniques in increasing order of model complexity are discussed. The first is based on adding data to an existing GP model. The second approach treats data from different sources as different noisy samples of a common underlying terrain and fusion is performed using heteroscedastic GPs. The final approach, based on dependent GPs, models each data set by a separate GP and learns spatial correlations between data sets through auto and cross covariances. The paper presents a unifying view of approaches to data fusion using GPs, a statistical evaluation that compares these approaches and multiple previously untested variants of them and an insight into the effect of model complexity on data fusion. Experiments suggest that in situations where data being fused is not rich enough to require a complex GP data fusion model or when computational resources are limited, the use of simpler GP data fusion techniques, which are constrained versions of the more generic models, reduces optimization complexity and consequently can enable superior learning of hyperparameters, resulting in a performance gain.     

Semi-transparent blotches removal from sepia images exploiting visibility laws

This paper presents a novel model for the removal of semi-transparent blotches on the digitized copy of sepia archive photographs. As these defects cannot be successfully eliminated by conventional interpolation methods, a proper combination of a novel visual distortion and multiresolution analysis is used for performing user-independent detection and restoration. Extensive experimental results and comparative studies show the potential of the proposed model in terms of visual quality and computational complexity.     

Structural and luminescence enhancement properties of Eu3＋/Ag nanocrystallites doped SiO2-TiO2 matrices

We reported here the structural and optical characterisation of silver nanocrystallites/Eu3+ :SiO2-TiO2 matrices synthesised through sol-gel route. Structural characterisations were done by using energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscope (AFM) and transmission electron microscopy (TEM) measurements and optical characterisations were performed by absorption and emission spectroscopy. The TEM and XRD measurements confirmed the presence of nanocrystals. A broad absorption band was observed due to surface plasmon resonance of silver nanocrystals. The effect of silver nanocrystals on the emission spectrum of Eu3+ doped SiO2-TiO2 matrices was discussed. An attempt was made to explain this fluorescence enhancement by invoking phenomena such as energy transfer, asymmetry ratio, surface plasmon, surface roughness, crystallinity and grain boundary. Our analysis, based on the experimental results, suggested that all the phenomena except crystallinity and grain boundary had favourable effects on fluorescence enhancement. We also estimated the relevant parameters associated with the phenomena that affected the fluorescence emission from the Eu3+ ions in the matrix. It was seen that the theoretical estimate of fluorescence enhancement agreed well with the experimental estimate.     

Propagation of Uncertainty in Establishing the Viscosity Scale

The viscosity scale is established by step up method, in which several master viscometers and standard liquids are used. Starting point is the distilled water. The basic measurand is the efflux time. Uncertainty in the determination of viscometer constant of a viscometer or the kinematic viscosity of standard liquid at a particular step is carried forward for subsequent steps. The expressions for uncertainty for viscometer constant of the viscometer and kinematic viscosity of the liquid in nth step have been derived. Various applicable corrections and their contribution to uncertainty have been discussed.     

Two-mode Gaussian product states in a lossy interferometer

The quantum Fisher information for a two-mode, Gaussian product state in an interferometer subject to photon loss is studied. We obtain the quantum Cramer–Rao bound on the achievable precision in phase estimation using such states. The scaling of the measurement precision with the mean photon number is compared to the shot noise-limited scaling for dual squeezed vacuum states and dual squeezed, displaced vacuum states.     

Self‐employment and local economic performance: Evidence from US counties*

This study explores the relationship between self‐employment and income growth, employment growth, and change in poverty in metro and non‐metro areas in the United States using county‐level panel data. We investigate the impact of the relative size of the self‐employment sector measured by the share of non‐farm proprietorships (NFPs) in total full and part‐time employment on three key economic performance indicators. We first estimate an income growth model to analyse the effects of self‐employment on income growth. Then we investigate the independent effects of self‐employment on employment growth and changes in family poverty rates. Our results indicate that higher self‐employment rates are associated with statistically significant increases over time in income and employment growth, and reductions in poverty rates in non‐metro counties. We find similar effects on metro county income and employment, but not on poverty dynamics.     

Poly(3-hexylthiophene) and hexafluoro-2-propanol-substituted polysiloxane based OFETs as a sensor for explosive vapor detection

The organic field effect transistors (OFETs) with regioregular poly 3-hexylthiophene (rr-P3HT) and hexafluoro-2-propanol-substituted polysiloxane (SXFA) as an organic layer, have been used for detection of explosive vapors with excellent sensitivity of less than 70 ppt for 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and less than 100 ppt for 2,4,6-trinitrotoluene (TNT). The sensor response (% change in saturation current) was found to be 125 ± 10% for TNT and 90 ± 10% for RDX. It was also observed that the incorporation of Cu^II tetraphenylporphyrin (CuTPP) into rr-P3HT/SXFA matrix resulted in an improved selectivity for the vapors of nitro based analytes (TNT, RDX and DNB) as compared to the vapors of non explosive oxidizing agents such as nitrobenzene (NB), benzoquinone (BQ) and benzophenone (BP). This is attributed to the increased binding of the vapors containing nitro compound to the thin films due to the presence of CuTTP. Spin coated thin films were further characterized by Atomic Force Microscopy (AFM) and Electrostatic Force Microscopy (EFM).     

Effect of Retrogression and Re-Aging on Tensile Mechanical Properties in Transverse Direction of Extruded Rods from Aluminum Alloy AA7049

Metal Science and Heat Treatment - The effect retrogression and re-aging (RRA treatment) on the tensile properties in the transverse direction of extruded rods from aluminum alloy AA7049 is...     

Modelling and kinetic aspects of a BTEX contaminated air-treating biofilter

In this study, the overall performance of a biofilter was evaluated in terms of its elimination capacity by using 3-D mesh techniques. The overall results indicate that the agreement between experimental data and model predictions is excellent for benzene, toluene, ethylbenzene and o-xylene (BTEX). In this study, the maximum removal rate (r _max) values for BTEX were 0.0117, 0.0126, 0.0081 and 0.0146 g m^–3 h^–1, and the half-saturation constant (K_S ) values were calculated to be 0.269, 0.297, 0.156 and 0.394 g m^–3, respectively. For this system, the coefficients of determination (r ²) of BTEX compounds were greater than 0.97. The BTEX concentration profiles along the depth were also determined using a convection–diffusion reactor (CDR) model. The sums of squares of the errors (SSEs) of BTEX were 0.0078, 0.0059, 0.0129 and 0.0269, respectively, with r ² values greater than 0.99 for all four compounds at low concentrations.