Synthesis and Photoluminescence characterization of NaMgSO4F: Ce phosphor

Ce3+ emission in NaMg(SO4)F  phosphor prepared by wet chemical method is reported in this paper. The synthesized phosphor is characterized by X-ray diffraction, photoluminescence excitation and emission spectra. The emission spectra shows a dominant peak at 349 nm due to the 5d→4f transition of Ce3 + when monitored at excitation wavelength of 263 nm. In this host very low concentration of cerium is used. The characteristic emission of the NaMg(SO4)F  phosphor in the UV region of spectrum makes it a strong candidate for the use in scintillation applications

PZT Based Smart Aggregate for Unified Health Monitoring of RC Structures

Abstract The most familiar civil engineering structure is reinforced concrete (RC) structure. Performance of structure undergoes changes during their service life with time. Thus, it is of great concern to monitor the health of RC structure. Structural health monitoring (SHM) is the art of detecting the changes in structure that influences its performance. Various techniques to monitor the health of structure are broadly studied worldwide. PZT based smart aggregate can play an effective role as an advanced tool in the development of structural health monitoring. This research work contributes for proposing a more generous Non-Destructive Evaluation (NDE) technique for structural health monitoring by using smart materials. If performance of a structure deviates from the design parameters with time, appropriate and effective maintenance is required. Considering the relevant need of RC structures, a more sensitive and cost-effective approach by using Electro-Mechanical Impedance (EMI) technique has been proposed for implementation in real-life situations. In general, surface bonded PZT transducer is used for SHM. Since PZT transducers are of very small dimension and brittle in nature, for consistent characteristics, they should be protected from severe environmental condition and other external interruptions. For this reason, PZT transducer is embedded in structure at the time of construction and manufacturing of the embedded transducer is simple. The proposed EMI technique assesses the health of RC structures more rationally by embedding PZT transducer in the structure, whose health is to be monitored over the user specified preset frequency range. The conductance and susceptance signatures are acquired by using LCR meter. At any future point of time, when it is desired to assess the health of structure, the conductance and susceptance signatures are acquired and further utilized for damage detection and quantification. The Root Mean Square Deviation (RMSD) is used to specify damage severity

Scan line optimization for Tri stereo planetary images

In this paper, we propose a new scan line optimization method for matching the triplet of images. In the present paper, the triplets are initially matched using an area based local method. The cost is stored in a structure called as the Disparity Space Image (DSI). Using the global minimum of this cost the initial disparity is generated. Next the local minima are considered as potential matches where global minimum gives erroneous results. These local minima are used for optimization of disparity. As the method is a scanned line optimization, it use popularly resampled images. The experiment is performed using Terrain Mapping Camera images from the Chandrayaan-1 mission. In order to validate the result for accuracy, Lunar Orbiter Laser Altimeter dataset from Lunar Reconnaissance Orbiter mission is used. The method is again verified using standard Middlebury stereo dataset with ground truth. From experiments, it has been observed that using optimization technique for triplets, the total number of correct matches has increased by 5–10 % in comparison to direct methods. The method particularly gives good results at smooth regions, where dynamic programming and blockmatching gives limited accuracy

Effect of Nd3+ on spectroscopic properties of lithium borate glasses

The spectroscopic properties of lithium borate glasses as a function of Nd3+ ions concentration were reported. Optical absorption spectra of these glasses showed a number of absorption bands in ultra violet and visible region. Optical absorption edge was found to shift towards the longer wavelength (red shift) with increase in Nd2O3. Luminescence spectra revealed three major bands at 902, 1063 and 1334 nm which was due to F-4(3/2) -> I-4(9/2), (11/2) (&) (13/2) transitions of Nd3+ ions. Luminescence intensity was maximum for 1 mol.% Nd2O3 and further increase in Nd2O3 resulted in luminescence quenching. The luminescence quenching behavior at higher concentration of Nd2O3 was attributed to the Nd3+-Nd3+ interaction in the glass matrix. An absorption and emission property of these glasses suggested that these glasses could be useful for 1.06 mu m infrared laser applications