Experimental factors affecting the within- and between-individual variation of plantar foot surface temperatures in turkeys (Meleagris gallopovo) recorded with infrared thermography

acceptedVersio

Hyperspektral avbildning som et verktøy for karakterisering av multikrystallinske skiver av silisium

This thesis describes the development of a method for characterization of multicrystalline silicon wafers based on hyperspectral imaging. The aim has been to show the distribution of radiative defects in silicon wafers. Commonly used methods are often time consuming and destructive or based on indirect measurements. Hyperspectral imaging is a fast, non-destructive method which measures the distribution of radiative defects directly. The exact mechanisms of the radiative defects are still not fully understood, but by using hyperspectral imaging in addition to complementary measurements, new knowledge of their origins can be obtained. One issue in this thesis has been to show the possibilities of using hyperspectral imaging to visualize radiative defects. In combination with multivariate curve resolution we can quickly extract the weak signals from the raw hyperspectral images. A research facility for cooled hyperspectral photoluminescence imaging, has in parallel with the experiments, been developed and tested. The laboratory consists of two hyperspectral cameras, excitation source and two cryogenic coolers. 50 wafers from a silicon block have been studied using the hyperspectral imaging setup. Additionally, RGB images, conventional photoluminescence images and interstitial iron mapping have been acquired. The different datasets have been preprocessed and corresponding points were located in all image types before an affine transform was performed to align them to a common coordinate system. Selected spectral defects were used to make 3D visualization to show the distribution of defects through the silicon block.Denne avhandlingen beskriver utviklingen av en metode for karakterisering av multikrystallinske silisiumskiver basert på hyperspektral avbildning. Målet har vært å vise utbredelsen av de forskjellige luminiserende defektene som er gjeldende i silisiumskiver. Dagens metoder for karakterisering av silisium er ofte tidkrevende, destruktive eller er indirekte målinger. Hyperspektral avbildning er en rask og ikke destruktiv målemetode som måler den radiative delen av defektene fra silisium direkte. Den fysiske årsaken til de radiative defektene er fortsatt ikke helt forstått, men ved å sammeligne hyperspektrale data med alternative målemetoder kan vi få en bedre forståelse om årsakene. Et aspekt ved denne avhandlingen er å vise hvilke muligheter det gir å bruke hyperspektralt kamera til å avbilde luminiserende defekter. I kombinasjon med multivariat statistikk kan en raskt ekstrahere de svake signalene fra defektene i bildene. Det er parallelt blitt utviklet og testet en forsøksrigg for hyperspektral fotoluminesens med mulighet for kjøling av prøvene ned til 80K. Oppsettet består av to hyperspektrale kamera, en linjelaser og to kjølte prøveholdere. 50 skiver fra en silisiumblokk er blitt studert med prøveoppsettet. I tillegg er det tatt fargebilder, konvensjonelle fotoluminesensbilder og utført måling av interstitielt jern av prøvene. De forskjellige datasettene er blitt preprosessert og felles punkter ble lokalisert i alle bildene før det ble kjørt en affin transformasjon for å gjøre bildene sammenlignbare. Utvalgte spektrale defekter ble valgt ut til en 3D visualisering for å vise utbredelsen gjennom silisiumblokken

Hyperspectral imaging as a tool for characterization of multicrystalline silicon wafers

This thesis describes the development of a method for characterization of multicrystalline silicon wafers based on hyperspectral imaging. The aim has been to show the distribution of radiative defects in silicon wafers. Commonly used methods are often time consuming and destructive or based on indirect measurements. Hyperspectral imaging is a fast, non-destructive method which measures the distribution of radiative defects directly. The exact mechanisms of the radiative defects are still not fully understood, but by using hyperspectral imaging in addition to complementary measurements, new knowledge of their origins can be obtained. One issue in this thesis has been to show the possibilities of using hyperspectral imaging to visualize radiative defects. In combination with multivariate curve resolution we can quickly extract the weak signals from the raw hyperspectral images. A research facility for cooled hyperspectral photoluminescence imaging, has in parallel with the experiments, been developed and tested. The laboratory consists of two hyperspectral cameras, excitation source and two cryogenic coolers. 50 wafers from a silicon block have been studied using the hyperspectral imaging setup. Additionally, RGB images, conventional photoluminescence images and interstitial iron mapping have been acquired. The different datasets have been preprocessed and corresponding points were located in all image types before an affine transform was performed to align them to a common coordinate system. Selected spectral defects were used to make 3D visualization to show the distribution of defects through the silicon block

Hyperspectral photoluminescence imaging of defects in solar cells

The present work is a demonstration of how near infrared (NIR) hyperspectral photoluminescence imaging can be used to detect defects in silicon wafers and solar cells. Chemometric analysis techniques such as multivariate curve resolution (MCR) and partial least squares discriminant analysis (PLS-DA) allow various types of defects to be classified and cascades of radiative defects in the samples to be extracted. It is also demonstrated how utilising a macro lens yields a spatial resolution of 30 µm on selected regions of the samples, revealing that some types of defect signals originate in grain boundaries of the silicon crystal, whereas other signals show up as singular spots. Combined with independent investigation techniques, hyperspectral imaging is a promising tool for determining origins of defects in silicon samples for photovoltaic applications

Hot chicks, cold feet

acceptedVersio

Monitoring and simulation of diurnal surface conditions of a wooden facade

The hygrothermal surface conditions of a façade is important for the degradation of the façade material as well as for the energy budget of the building. The distribution of short term variations of the temperature and moisture in the façade is often neglected in degradation studies that will typically treat the whole façade equally. The moisture and temperature variations are especially important in porous building materials where water dependent biological and physical processes are the main degrading factors. In this study the diurnal cycle of the surface temperature is measured with conventional temperature probes as well as with infra-red camera. In addition, the moisture content of the wooden façade is measured with resistive measurement technique. The measurements are used to validate simulations of the spatial temperature and moisture variations on the façade. The study shows large variations of surface conditions on the façade and that the simulations reproduces the measurements within a high degree of accuracy.publishedVersio

Effects of subclinical footpad dermatitis and emotional arousal on surface foot temperature recorded with infrared thermography in turkey toms (Meleagris gallopavo)

acceptedVersio

Controlled infrared heating of an artic meadow: challenge in the vegetation establishment stage

Background: Global warming is going to affect both agricultural production and carbon storage in soil worldwide. Given the complexity of the soil-plant-atmosphere continuum, in situ experiments of climate warming are necessary to predict responses of plants and emissions of greenhouse gases (GHG) from soils. Arrays of infrared (IR) heaters have been successfully applied in temperate and tropical agro-ecosystems to produce uniform and large increases in canopy surface temperature across research plots. Because this method had not yet been tested in the Arctic where consequences of global warming on GHG emission are expected to be largest, the objective of this work was to test hexagonal arrays of IR heaters to simulate a homogenous 3 °C warming of the surface, i.e. canopy and visible bare soil, of five 10.5-m2 plots in an Arctic meadow of northern Norway. Results: Our results show that the IR warming setup was able to simulate quite accurately the target + 3 °C, thereby enabling us to simulate the extension of the growing season. Meadow yield increased under warming but only through the lengthening of the growing season. Our research also suggests that, when investigating agricultural systems on the Arctic, it is important to start the warming after the vegetation is established,. Indeed, differential emergence of meadow plants impaired the homogeneity of the warming with patches of bare soil being up to 9.5 °C warmer than patches of vegetation. This created a pattern of soil crusting, which further induced spatial heterogeneity of the vegetation. However, in the Arctic these conditions are rather rare as the soil exposed by snow melt is often covered by a layer of senescent vegetation which shelters the soil from direct radiation. Conclusions: Consistent continuous warming can be obtained on average with IR systems in an Arctic meadow, but homogenous spatial distribution requires that the warming must start after canopy closure

Controlled infrared heating of an artic meadow: challenge in the vegetation establishment stage

Background: Global warming is going to affect both agricultural production and carbon storage in soil worldwide. Given the complexity of the soil-plant-atmosphere continuum, in situ experiments of climate warming are necessary to predict responses of plants and emissions of greenhouse gases (GHG) from soils. Arrays of infrared (IR) heaters have been successfully applied in temperate and tropical agro-ecosystems to produce uniform and large increases in canopy surface temperature across research plots. Because this method had not yet been tested in the Arctic where consequences of global warming on GHG emission are expected to be largest, the objective of this work was to test hexagonal arrays of IR heaters to simulate a homogenous 3 °C warming of the surface, i.e. canopy and visible bare soil, of five 10.5-m2 plots in an Arctic meadow of northern Norway. Results: Our results show that the IR warming setup was able to simulate quite accurately the target + 3 °C, thereby enabling us to simulate the extension of the growing season. Meadow yield increased under warming but only through the lengthening of the growing season. Our research also suggests that, when investigating agricultural systems on the Arctic, it is important to start the warming after the vegetation is established,. Indeed, differential emergence of meadow plants impaired the homogeneity of the warming with patches of bare soil being up to 9.5 °C warmer than patches of vegetation. This created a pattern of soil crusting, which further induced spatial heterogeneity of the vegetation. However, in the Arctic these conditions are rather rare as the soil exposed by snow melt is often covered by a layer of senescent vegetation which shelters the soil from direct radiation. Conclusions: Consistent continuous warming can be obtained on average with IR systems in an Arctic meadow, but homogenous spatial distribution requires that the warming must start after canopy closure

Experimental factors affecting the within- and between-individual variation of plantar foot surface temperatures in turkeys (Meleagris gallopovo) recorded with infrared thermography

acceptedVersio