1,045 research outputs found

    Portable Hyperspectral Imaging Device for Surface Sanitation Verification in the Produce Industry

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    Produce processors must clean and sanitize surfaces before production to reduce the risk of foodborne illness. Current surface hygiene verification methods require direct surface sub-sampling at selected locations and a wait time. To augment these methods, a portable hyperspectral imaging device was developed to find potential contaminants in real-time and increase sub-sampling effectiveness. Analysis of hyperspectral fluorescence images showed that fresh-cut produce processing exudates in the regions of 460-540 and 670-680 nm are detectable from background materials, while select cleaning agents are not. The portable single operator imaging system includes a charge coupled device (CCD) camera, tunable optical filter, laptop, light emitting diodes (LED's) for fluorescence excitation, and a touchscreen display. Within a commercial plant, fluorescence imaging identified produce processing residuals following routine cleaning procedures that were not readily visible to the naked eye. These tests demonstrate the system's potential to enhance post-cleaning inspection, and helped improve routine cleaning procedures

    Hyperspectral imaging for detection of corrosion on intermediate level nuclear waste containers

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    Intermediate level nuclear waste (ILW) will be stored above ground in 304L stainless steel (SS) containers for the next 100 years. During this period, the containers need to be monitored for atmospheric pitting corrosion - a known precursor of atmospherically induced stress corrosion cracking. Hyperspectral (HS) and optical imaging of pitting corrosion products from droplet experiments have been investigated towards developing a system for long term monitoring of atmospheric pitting corrosion of stainless steel containers in ILW stores. Common corrosion products were first identified via Raman spectroscopic mapping as akaganeite (β-FeOOH) and lepidocrocite (γ-FeOOH), with a secondary presence of layered double hydroxide (green rust). HS and optical methods were then compared for their efficacy at rust detection. Whilst it was not possible to identify specific corrosion species using HS imaging, HS images of rust under pitted droplets provided better contrast with the background steel than colour photography due to species having lower absorbance the near infrared (850 nm) than red (650 nm). Finally, the relationship between rust area and pit volume was determined by comparing colour photography (rust area) with confocal laser scanning microscopy (pit volume). A good correlation was present for samples exposed to a fixed relative humidity (RH) for MgCl2 droplets and CaCl2 droplets with small pit volumes. Poor correlation was found for samples exposed to natural fluctuations in RH. It was concluded that optical methods are viable for the detection of rust, but less effective for quantification of pit volumes

    New Methods for ferrous raw materials characterization in electric steelmaking

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    425 p.In the siderurgical sector, the steel scrap is the most important raw material in electric steelmaking,contributing between 70% of the total production costs. It is well-known how the degree of which thescrap mix can be optimized, and also the degree of which the melting operation can be controlled andautomated, is limited by the knowledge of the properties of the scrap and other raw-materials in thecharge mix.Therefore, it is of strategic importance having accurate information about the scrap composition of thedifferent steel scrap types. In other words, knowing scrap characteristics is a key point in order to managethe steel-shop resources, optimize the scrap charge mix/composition at the electric arc furnace (EAF),increase the plant productivity, minimize the environmental footprint of steelmaking activities and tohave the lowest total cost of ownership of the plant.As a main objective of present doctoral thesis, the doctorate will provide new tools and methods of scrapcharacterization to increase the current recycling ration, through better knowledge of the quality of thescrap, and thus go in the direction of a 100% recycling ratio. In order to achieve it, two main workinglines were developed in present research. Firstly, it was analysed not only the different existingmethodologies for scrap characterization and EAF process optimization, but also to develop new methodsor combination of existing, Secondly, it was defined a general recommendations guide for implementingthese methods based on the specifics of each plant

    Remote sensing based on hyperspectral data analysis

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    In remote sensing, accurate identification of far objects, especially concealed objects is difficult. In this study, to improve object detection from a distance, the hyperspecral imaging and wideband technology are employed with the emphasis on wideband radar. As the wideband data includes a broad range of frequencies, it can reveal information about both the surface of the object and its content. Two main contributions are made in this study: 1) Developing concept of return loss for target detection: Unlike typical radar detection methods which uses radar cross section to detect an object, it is possible to enhance the process of detection and identification of concealed targets using the wideband radar based on the electromagnetic characteristics conductivity, permeability, permittivity, and return loss of materials. During the identification process, collected wideband data is evaluated with information from wideband signature library which has already been built. In fact, several classes (e.g. metal, wood, etc.) and subclasses (ex. metals with high conductivity) have been defined based on their electromagnetic characteristics. Materials in a scene are then classified based on these classes. As an example, materials with high electrical conductivity can be conveniently detected. In fact, increasing relative conductivity leads to a reduction in the return loss. Therefore, metals with high conductivity (ex. copper) shows stronger radar reflections compared with metals with low conductivity (ex. stainless steel). Thus, it is possible to appropriately discriminate copper from stainless steel. 2) Target recognition techniques: To detect and identify targets, several techniques have been proposed, in particular the Multi-Spectral Wideband Radar Image (MSWRI) which is able to localize and identify concealed targets. The MSWRI is based on the theory of robust capon beamformer. During identification process, information from wideband signature library is utilized. The WB signature library includes such parameters as conductivity, permeability, permittivity, and return loss at different frequencies for possible materials related to a target. In the MSWRI approach, identification procedure is performed by calculating the RLs at different selected frequencies. Based on similarity of the calculated RLs and RL from WB signature library, targets are detected and identified. Based on the simulation and experimental results, it is concluded that the MSWRI technique is a promising approach for standoff target detection

    High concentrations of plastic hidden beneath the surface of the Atlantic Ocean

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    Concern over plastic pollution of the marine environment is severe. The mass-imbalance between the plastic litter supplied to and observed in the ocean currently suggests a missing sink. However, here we show that the ocean interior conceals high loads of small-sized plastic debris which can balance and even exceed the estimated plastic inputs into the ocean since 1950. The combined mass of just the three most-littered plastics (polyethylene, polypropylene, and polystyrene) of 32–651 µm size-class suspended in the top 200 m of the Atlantic Ocean is 11.6–21.1 Million Tonnes. Considering that plastics of other sizes and polymer types will be found in the deeper ocean and in the sediments, our results indicate that both inputs and stocks of ocean plastics are much higher than determined previously. It is thus critical to assess these terms across all size categories and polymer groups to determine the fate and danger of plastic contamination

    Spectral Imaging for Mars Exploration

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    Numerical and experimental methods for design and test of units and devices on BepiColombo Mission

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    In this thesis work several numerical and experimental methods for design and test of units and devices onboard BepiColombo Mission are studied, implemented and described. BepiColombo Mission is the result of the joined efforts of European Space Agency and Japanese Space Agency: in 2015 two different orbiters (ESA Mercury Planetary Orbiter, MPO, which will support remote sensing and radio-science instrumentation, and JAXA Mercury Magnetospheric Orbiter, MMO) will be launched in the direction of Mercury to study the surface composition and morphology, the geology and the magnetosphere of the planet closest to the Sun. Italy plays an important role in the mission since it is involved in the design and development of the Spectrometer and Imagers for Mpo Bepicolombo Integrated Observatory SYStem (SIMBIO-SYS): this integrated package of instruments includes an imaging system with stereo (STC) and high spatial resolution (HRIC) capabilities along with a hyperspectral imager (VIHI) in the visible and near infrared range. Due to the proximity to the Sun, MPO will face an extremely harsh environment from a thermal point of view, therefore the orbiter, and in particular instrumentation exposed to the thermal fluxes, shall be equipped with sophisticated thermal control devices, such as baffling systems for heat rejection. Starting from the deep knowledge of the thermal scenario in which units and baffles will operate, thanks to the results obtained from detailed thermal and mathematical models, different innovative test-beds have been conceived and designed in order to simulate the environmental thermal fluxes in laboratory. At first, the Structural Thermal Models of SIMBIO-SYS baffles have been tested, subjecting the devices to the environmental infrared fluxes provided by infrared lamps and cold sources in vacuum conditions and assuring different temperature levels on the thermal interfaces of the units; after the test campaign, the thermal mathematical models of the baffles themselves have been validated thanks to the correlation with the experimental results, providing some useful information on the design of the Flight Models of the baffles. Afterwards an original set-up to test the Qualification Model of the Stavroudis baffle of HRIC unit has been designed: during tests, scheduled in January and February 2013, also solar fluxes will be simulated, thanks to CISAS solar simulator, with the aim to qualify the instrument reproducing in vacuum the maximum and minimum operative and non operative temperatures and the most critical heat fluxes (solar and infrared) in sequence. In parallel to this activity, from the need to calibrate and qualify the units in space-like environment simulating the operative conditions, two thermal vacuum chambers have been designed: calibration will be performed for HRIC and STC-VIHI units separately, with and without baffles. The activity started from the comprehension of the instruments calibration requirements and proceeded with the conceptual design of the units, the detailed thermal, structural and electrical design and concluded with the procurement, the assembling and the test activity, which has been performed in order to verify the initial requirements. Thanks to these activities, a series of methods, procedures and techniques, both numerical and experimental, have been developed and validated, with the aim to provide an original and useful contribution to the design and test of SIMBIO-SYS suite onboard BepiColombo missio
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