The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A sparseness constrained approach is proposed for linear unmixing, and the results are used for hybrid detection of hyperspectral imagery. The sparseness constraint is imposed on the abundance fractions, resulting in better performance than the popular non-negative and fully constrained methods, particularly in the situations when background endmember spectra are not accurately acquired or estimated,...
This study aims at improving the spatial resolution for the pulsed electro-acoustic method — PEA. Indeed, the actual spatial resolution of this method is in order of ten μm while dielectric films used as thermal regulators in the structures of the satellites and analyzed by the PEA method are around 50-μm-thick. Also a better resolution is expected to provide a better description of charges in these...
The timely and accurate detection of threat contraband especially for ports-of-entry (e.g. harbors, bays, borders, airports) is an extremely critical problem of national security. The investigation of advanced techniques to reliably and accurately detect threats and reject non-threats is the major focus of this effort. The characterization of signal processing models based on xray transport physics...
This paper presents the preliminary results of using silicon nanowires for the fabrication of electron detectors suitable for scanning electron microscopy. The rather small size of the device allows its location just close to the specimen, hence increasing the detected current with no need to a complex optical device. The results of material variation as well as preliminary results of morphology changes...
Design and fabrication of dielectric lenses for terahertz (THz) focal plane arrays are presented in this paper. Lenses are designed using optical lens and ellipsoid function theory in the terahertz range (centered at f = 300GHz). In order to enhance coupling to planar circuits on wafer, two types of lenses are considered: modified hemispherical, such as extended hemispherical and hypo-hemispherical...
With the development of economy urbanisation and technology it is necessary to design intelligent energy saving lighting systems [2], and efficient power management on ATM counters. The information of pedestrians and the ATM users are sensed by the pyroelectric infrared sensors. The sensors are placed on the door pole, thus the selection and installation of sensors are directly affect the control...
Though some encounters with potentially illicit radiological or nuclear material involve a stationary or dwell survey, many of the conceivable encounters are dynamic in nature. In the general unshielded or homogeneously shielded dynamic encounter, the mean detectable source signature strength will follow a well behaved curve with time: increasing on approach, peaking at the point-of-closest-approach,...
We report on the development of a neutron detector utilizing solid enriched lithium, which has substantial neutron detection efficiency. The detector employs large, thin sheets of lithium in a gas-filled multi-wire proportional chamber (MWPC). Using low-cost design methods, readout electronics, and a small fraction of the already available enriched lithium available from Y-12/Oak Ridge National Laboratory,...
A plastic optical fibre (POF) dosimeter for measuring ionising radiation during radiotherapy applications is presented. Previous initial results involving this type of sensor using an x-ray scintillating material have been reported by McCarthy et al[1]. This paper details results, using a different type of scintillating material (UKL65/L-R1-sourced from Phosphor Technologies in the UK)[2] which is...
New developments in detector technology allow the acquisition of micrometer-resolution x-ray transmission images of specimens as large as a few millimeters at unprecedented frame rates. The high x-ray flux density generated by the Advanced Photon Source (APS) allows for detector exposure times ranging from hundreds of milliseconds to 150 picoseconds. The synchronization of the camera with the rotation...
We discuss the problem of combining biometric match scores with liveness measure values in the context of fingerprint verification. Recent literature has focused on the development of methods to assess if an input fingerprint sample is a “live” entity or a “spoof” artefact. This is commonly done by generating a single-valued numerical entity referred to as the liveness measure value. However, the...
A novel compressive edge-detection algorithm for spectral imagery is demonstrated using real long-wave spectral imagery. The idea of the algorithm is based on identifying joint spatial and spectral features via statistical learning.
Positron annihilation spectroscopy techniques are sensitive laboratory methods of in-depth study of the material structure and processes occurring in it. The digital spectrometric system described in this paper is designed to study the defect structure of materials by positron annihilation spectroscopy techniques. This system combines the methods of positron annihilation lifetime spectroscopy and...
The use of transmission electron tomography for three dimensional morphology analysis of nanostructured materials has grown significantly in recent years due to the improved robustness of automated image collection, alignment and reconstruction routines. Although the amount of published 3D electron tomography data has increased accordingly, in many cases the data is used purely for visualization purposes,...
We investigate the use of pulsed bremsstrahlung as a standoff active interrogation tool for the production of neutron and gamma signatures in fissionable materials.1 Photons are generated by an electron beam striking a Ta converter on the 16 MV Hermes III facility at Sandia National Laboratories, and propagate to a target location 19 m from the electron beam diode, at which various materials are placed...
In this work we consider the enhancement of ultimate performance of semiconductor infrared detectors utilizing nanoplasmonics. To this purpose we analyze the application of transparent conductive oxides (TCO) as plasmonic material with the plasma frequency in the near infrared. We investigate the possibility to apply TCO nanoparticles for field localization embedded into a dielectric host. We consider...
We have developed a computer program that simulates the electrical characteristics of a p+ − n HgCdTe photodetector. Using solutions to the Poisson and Continuity equations we investigate low temperature behavior to determine optimum working conditions to enhance detectivity. Our model considers complete Fermi — Dirac statistics, major recombination mechanisms, band to band tunneling, trap assisted...
The free charge carrier lifetime is a highly sensitive parameter that can be used for analyzing the function of semiconductor devices and monitoring the quality of wafer materials. In this context, time-resolved photoluminescence (TRPL) is presented as a technique for directly determining the free charge carrier lifetime with pulsed diode laser excitation and time-correlated single photon counting,...
The e-carboline compound and evodiamine were synthesized with improved Bischler-Napieralski-type and Diels-Alder-type reactions by taking tryptamine and N-methyl anthranilic acid as starting materials, enjoying the characteristics of few steps, simple ness, mild reaction conditions, high productivity and less pollution etc. Conduct elementary analyses on the resulting compounds and characterize them...
We propose a system where an Organic PhotoDetector (OPD) is realized directly onto the cleaved surface of a standard polymethylmethacrylate (PMMA)-based Plastic Optical Fiber (POF). The OPD photoactive layer is based on the bulk-heterojunction of [6,6]-phenyl-C61-butyric acid methyl ester with a squaraine dye, whose absorption spectrum well matches the POF minimum loss window in the red (around 650nm)...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.