Littérature scientifique sur le sujet « Infra-Red Band »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Infra-Red Band ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Infra-Red Band"
1
Sudhakar Reddy, B., K. Vemasevana Raju, S. Sailaja, C. Nageswara Raju et D. Sreekantha Reddy. « NIR Emission Analysis of Er3+/Yb3+ and Er3+/ Tm3+ Ions Doped Zinc lithium Boro Tellurite (ZLiBT) Glasses for Optical Fiber Amplification ». Advanced Materials Research 123-125 (août 2010) : 19–22. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.19.
Texte intégralRésumé :
This paper reports on the development and the near infra-red emission(NIR) analysis of Er3+/Yb3+ and Er3+/ Tm3+ ions doped TeO2 - B2O3 – ZnO - Li2O glasses for tunable laser and optical fiber amplification. From the measured near infra-red emission spectra of Er3+/Yb3+, Er3+/Tm3+: ZLiBT glasses have revealed the prominent near infra-red emission bands at 1532 nm (4I13/2 → 4I15/2), with an excitation wavelength of λexci = 515 nm (Ar+ ion laser). The full width at half-maxima (FWHM) values are also estimated from the measured near infra-red emission spectra of the glasses. Based on spectral results, broad near infra-red emissions should have potential applications in broadly tunable laser sources and broad band optical amplification at low-loss telecommunication windows.
2
Zhao, Liang, Jixue Liu, Stefan Peters, Jiuyong Li, Simon Oliver et Norman Mueller. « Investigating the Impact of Using IR Bands on Early Fire Smoke Detection from Landsat Imagery with a Lightweight CNN Model ». Remote Sensing 14, no 13 (25 juin 2022) : 3047. http://dx.doi.org/10.3390/rs14133047.
Texte intégralRésumé :
Smoke plumes are the first things seen from space when wildfires occur. Thus, fire smoke detection is important for early fire detection. Deep Learning (DL) models have been used to detect fire smoke in satellite imagery for fire detection. However, previous DL-based research only considered lower spatial resolution sensors (e.g., Moderate-Resolution Imaging Spectroradiometer (MODIS)) and only used the visible (i.e., red, green, blue (RGB)) bands. To contribute towards solutions for early fire smoke detection, we constructed a six-band imagery dataset from Landsat 5 Thematic Mapper (TM) and Landsat 8 Operational Land Imager (OLI) with a 30-metre spatial resolution. The dataset consists of 1836 images in three classes, namely “Smoke”, “Clear”, and “Other_aerosol”. To prepare for potential on-board-of-small-satellite detection, we designed a lightweight Convolutional Neural Network (CNN) model named “Variant Input Bands for Smoke Detection (VIB_SD)”, which achieved competitive accuracy with the state-of-the-art model SAFA, with less than 2% of its number of parameters. We further investigated the impact of using additional Infra-Red (IR) bands on the accuracy of fire smoke detection with VIB_SD by training it with five different band combinations. The results demonstrated that adding the Near-Infra-Red (NIR) band improved prediction accuracy compared with only using the visible bands. Adding both Short-Wave Infra-Red (SWIR) bands can further improve the model performance compared with adding only one SWIR band. The case study showed that the model trained with multispectral bands could effectively detect fire smoke mixed with cloud over small geographic extents.
3
Merlin Mathew, Rincy, S. Purushothaman et P. Rajeswari. « Performance comparisons of particle swarm optimization, echo state neural network and genetic algorithm for vegetation segmentation ». International Journal of Engineering & ; Technology 7, no 1.1 (21 décembre 2017) : 184. http://dx.doi.org/10.14419/ijet.v7i1.1.9286.
Texte intégralRésumé :
This article presents the implementation of vegetation segmentation by using soft computing methods: particle swarm optimization (PSO), echostate neural network(ESNN) and genetic algorithm (GA). Multispectral image with the required band from Landsat 8 (5, 4, 3) and Landsat 7 (4, 3, 2) are used. In this paper, images from ERDAS format acquired by Landsat 7 ‘Paris.lan’ (band 4, band 3, Band 2) and image acquired from Landsat 8 (band5, band 4, band 3) are used. The soft computing algorithms are used to segment the plane-1(Near infra-red spectra) and plane 2(RED spectra). The monochrome of the two segmented images is compared to present performance comparisons of the implemented algorithms.
4
He Guangzong, 何光宗, 熊长新 Xiong Changxin, 李钱陶 Li Qiantao et 吴小丽 Wu Xiaoli. « Dual Band Infra-Red Protective Coatings on Germanium Substrate ». Acta Optica Sinica 31, s1 (2011) : s100105. http://dx.doi.org/10.3788/aos201131.s100105.
Texte intégral
5
Rathborne, J. M., et M. G. Burton. « Results from the South Pole Infra-Red EXplorer Telescope ». Highlights of Astronomy 13 (2005) : 937–44. http://dx.doi.org/10.1017/s153929960001769x.
Texte intégralRésumé :
AbstractThe SPIREX telescope, located at the Amundsen-Scott South Pole Station, was a prototype system developed to exploit the excellent conditions for IR observing at the South Pole. Observations over two winter seasons achieved remarkably deep, high-resolution, wide-field images in the 3-5 μm wavelength regime. Several star forming complexes were observed, including NGC 6334, Chamaeleon I, η Chamaeleontis, the Carina Nebula, 30 Doradus, RCW 57, RCW 38, as well as the Galactic Center. Images were obtained of lines at 2.42/μm H2, 3.29/μm PAH and 4.05/μm Br α, as well as 3.5/μm L-band and 4.7 μm M-band continuum emission. These data, combined with near-IR, mid-IR, and radio continuum maps, reveal the environments of these star forming sites, as well as any protostars lying within them. The SPIREX project, its observing and reduction methods, and some sample data are summarized here.
6
Gossn, Juan, Kevin Ruddick et Ana Dogliotti. « Atmospheric Correction of OLCI Imagery over Extremely Turbid Waters Based on the Red, NIR and 1016 nm Bands and a New Baseline Residual Technique ». Remote Sensing 11, no 3 (22 janvier 2019) : 220. http://dx.doi.org/10.3390/rs11030220.
Texte intégralRésumé :
A common approach to the pixel-by-pixel atmospheric correction of satellite water colour imagery is to calculate aerosol and water reflectance at two spectral bands, typically in the near infra-red (NIR, 700–1000 nm) or the short-wave-infra-red (SWIR, 1000–3000 nm), and then extrapolate aerosol reflectance to shorter wavelengths. For clear waters, this can be achieved simply for NIR bands, where the water reflectance can be assumed negligible i.e., the “black water” assumption. For moderately turbid waters, either the NIR water reflectance, which is non-negligible, must be modelled or longer wavelength SWIR bands, with negligible water reflectance, must be used. For extremely turbid waters, modelling of non-zero NIR water reflectance becomes uncertain because the spectral slopes of water and aerosol reflectance in the NIR become similar, making it difficult to distinguish between them. In such waters the use of SWIR bands is definitely preferred and the use of the MODIS bands at 1240 nm and 2130 nm is clearly established although, on many sensors such as the Ocean and Land Colour Instrument (OLCI), such SWIR bands are not included. Instead, a new, cheaper SWIR band at 1016 nm is available on OLCI with potential for much better atmospheric correction over extremely turbid waters. That potential is tested here. In this work, we demonstrate that for spectrally-close band triplets (such as OLCI bands at 779–865–1016 nm), the Rayleigh-corrected reflectance of the triplet’s “middle” band after baseline subtraction (or baseline residual, BLR) is essentially independent of the atmospheric conditions. We use the three BLRs defined by three consecutive band triplets of the group of bands 620–709–779–865–1016 nm to calculate water reflectance and hence aerosol reflectance at these wavelengths. Comparison with standard atmospheric correction algorithms shows similar performance in moderately turbid and clear waters and a considerable improvement in extremely turbid waters.
7
Unavane, M., et G. Gilmore. « 2.6. Resolved near-IR survey of the inner Galaxy ». Symposium - International Astronomical Union 184 (1998) : 69–70. http://dx.doi.org/10.1017/s0074180900084059.
Texte intégralRésumé :
The analysis of resolved DENIS (Deep Near Infra Red Survey of the Southern Sky) I,J and K band data shows good evidence (≳ 3σ) in the J and K band number counts to support the existence of a kiloparsec-scale bar with its major axis in the first quadrant. A star by star dereddening of this K data combined with supplementary nbL band data (3.6μm) gives number count contrasts consistent with low angle (≲ 20 degrees) bar models in the literature.
8
Lee, Heesu, Seungjin Hwang, Sungyoon Lee, Kyung Hee Hong, Hyeon-Myeong Oh, Young-Jo Park, Ha-Neul Kim et Tae Jun Yu. « Measurement of Nd:Y2O3 broad band near infra-red transmittance using FTIR system ». Optical Materials 143 (septembre 2023) : 114227. http://dx.doi.org/10.1016/j.optmat.2023.114227.
Texte intégral
9
Dr. S.Varadarajan, A. Rajani,. « Estimation and Validation of Land Surface Temperature by using Remote Sensing & ; GIS for Chittoor District, Andhra Pradesh ». Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no 5 (11 avril 2021) : 607–17. http://dx.doi.org/10.17762/turcomat.v12i5.1059.
Texte intégralRésumé :
Land Surface Temperature (LST) quantification is needed in various applications like temporal analysis, identification of global warming, land use or land cover, water management, soil moisture estimation and natural disasters. The objective of this study is estimation as well as validation of temperature data at 14 Automatic Weather Stations (AWS) in Chittoor District of Andhra Pradesh with LST extracted by using remote sensing as well as Geographic Information System (GIS). Satellite data considered for estimation purpose is LANDSAT 8. Sensor data used for assessment of LST are OLI (Operational Land Imager) and TIR (Thermal Infrared). Thermal band contains spectral bands of 10 and 11 were considered for evaluating LST independently by using algorithm called Mono Window Algorithm (MWA). Land Surface Emissivity (LSE) is the vital parameter for calculating LST. The LSE estimation requires NDVI (Normalized Difference Vegetation Index) which is computed by using Band 4 (visible Red band) and band 5 (Near-Infra Red band) spectral radiance bands. Thermal band images having wavelength 11.2 µm and 12.5 µm of 30th May, 2015 and 21st October, 2015 were processed for the analysis of LST. Later on validation of estimated LST through in-suite temperature data obtained from 14 AWS stations in Chittoor district was carried out. The end results showed that, the LST retrieved by using proposed method achieved 5 per cent greater correlation coefficient (r) compared to LST retrieved by using existing method which is based on band 10.
10
Ilehag, R., M. Weinmann, A. Schenk, S. Keller, B. Jutzi et S. Hinz. « REVISITING EXISTING CLASSIFICATION APPROACHES FOR BUILDING MATERIALS BASED ON HYPERSPECTRAL DATA ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W3 (19 octobre 2017) : 65–71. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w3-65-2017.
Texte intégralRésumé :
Classification of materials found in urban areas using remote sensing, in particular with hyperspectral data, has in recent times increased in importance. This study is conducting classification of materials found on building using hyperspectral data, by using an existing spectral library and collected data acquired with a spectrometer. Two commonly used classification algorithms, Support Vector Machine and Random Forest, were used to classify the materials. In addition, dimensionality reduction and band selection were performed to determine if selected parts of the full spectral domain, such as the Short Wave Infra-Red domain, are sufficient to classify the different materials. We achieved the best classification results for the two datasets using dimensionality reduction based on a Principal Component Analysis in combination with a Random Forest classification. Classification using the full domain achieved the best results, followed by the Short Wave Infra-Red domain.
Thèses sur le sujet "Infra-Red Band"
1
Paul, Jyotirmay. « Design and development of adaptive optics system in visible and near infra-red-band for IUCAA 2 M Telescope ». Thesis, University of North Bengal, 2019. http://ir.nbu.ac.in/handle/123456789/4041.
Texte intégral
2
Yang, Wenjie. « Characterising and understanding Au-hyperdoped Si for sub-band gap optical absorption ». Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/154257.
Texte intégralRésumé :
The unparalleled technological maturity of silicon (Si) can be exploited to develop CMOS-compatible optoelectronics such as photodetectors and imaging arrays. However, the low-attenuation wavelengths commonly used in fibre-optics (up to 1650 nm) fall below the 1.12 eV band gap of Si (efficient absorption only occurs at wavelengths less than 1100 nm), thus requiring the realisation of sub-band gap photoresponse. A promising method to achieve this is to add an intermediate band within the band gap by incorporating appropriate impurities into the Si lattice at high concentrations (often beyond the thermodynamic solubility limit), or hyperdoping. Indeed, Au-hyperdoped Si made by ion implantation and pulsed laser melting (PLM) has been shown to exhibit strong sub-band gap optical absorption in the near-infrared and has led to the demonstration of a Si-based near-IR photodetector. The Au sub-band gap absorption has been shown to increase with the Au dose, and significant room for further improvement of the device performance has been predicted. While these results illustrate the potential of hyperdoped Si for photodetection in the near-infrared, the material properties of Au- and other transition-metal-hyperdoped Si remain elusive. With this as a premise, this PhD work has focused on characterising and understanding the properties of Au-hyperdoped Si. In this thesis, detailed Rutherford backscattering spectrometry and channeling measurements are undertaken to examine the lattice position of the Au atoms. It is shown that the Au occupies mostly substitutional lattice positions within the hyperdoped Si lattice. In addition, by varying the iplant energy and the implanted Au dose, thicker layers of Au-hyperdoped Si with higher Au concentrations are demonstrated. However, although the Au atoms remain significantly substitutional (more than 50% substitutional in most cases) at high Au concentrations, the Au distribution is found to be non-uniform. Further structural characterisation by transmission electron microscopy and energy dispersive spectroscopy reveals a new observation where filaments of single crystalline, Au-rich Si regions emerge after PLM. The local concentration within such filaments is estimated to be at least 3 at. %, and the proximate Si lattice is found to be slightly skewed. These features suggest a novel segregation regime in Au-hyperdoped Si that is distinctly different to conventional 'cellular breakdown' in hyperdoped Si, in which impurity precipitation might be observed at cell-walls. In spite of the inhomogeneous behaviour of Au-hyperdoped Si at high Au concentrations, the sub-band gap optical absorption is found to continue to increase with increasing substitutional Au dose. This is consistent with density functional theory calculations in which the isolated substitutional Au configuration is found to give rise to significant sub-band gap optical absorption. This enhancement in sub-band gap optical absorption is found to deactivate after subsequent thermal annealing. We show that this behaviour can be correlated with a loss of Au substitutionality. Furthermore, the detailed atomistic mechanism for the thermal relaxation of Au-hyperdoped Si is investigated by correlating the experimental observations with density functional theory results. We show that the thermal relaxation of Au-hyperdoped Si is a multi-step process which involves (1) the exchange of substitutional Au with interstitial Au, (2) the trapping of Au to local sinks, (3) the formation of Au dimers, and (4) the clustering and nucleation of Au precipitates. Furthermore, the activation energy associated with loss of Au substitutionality is found to be 1.6 eV, a similar value to the diffusion of Au in defective Si. In the final chapter of this work, experimental evidence for a vacancy trapping model is presented. We propose that vacancies are introduced during the resolidification process to minimise local strain around Au-rich regions. Furthermore, the trapped vacancies are shown to be decorated with Au after subsequent thermal annealing. We show that such a behaviour is not limited to Au-hyperdoped Si and may be a universal phenomenon that occurs during the incorporation of large size impurities into Si as the Si is rapidly resolidified from a laser-induced melt.
Chapitres de livres sur le sujet "Infra-Red Band"
1
Vuong, T. H. H., et R. J. Nicholas. « A Study of Thermally Activated Conduction, Hall Effect and Infra-Red Absorption from the Impurity Band in n-InP ». Dans Proceedings of the 17th International Conference on the Physics of Semiconductors, 705–8. New York, NY : Springer New York, 1985. http://dx.doi.org/10.1007/978-1-4615-7682-2_157.
Texte intégral
2
Landon, Preston B., Bog G. Kim, Ray H. Baughman, Robert Glosser, Anvar A. Zakhidov, Vladimir Kamaev et Valy Vardeny. « Functional Polymeric Photonic Crystals for Infra-Red Bands by Guided Colloidal Assembly Techniques ». Dans Organic Nanophotonics, 483–92. Dordrecht : Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0103-8_41.
Texte intégralActes de conférences sur le sujet "Infra-Red Band"
1
Doel, P., D. Buscher, C. Dunlop, R. Sharples et N. Andrews. « Recent Results from the MARTINI III/WHIRCAM Infra-red Adaptive Optics System ». Dans Adaptive Optics. Washington, D.C. : Optica Publishing Group, 1995. http://dx.doi.org/10.1364/adop.1995.mc3.
Texte intégralRésumé :
The MARTINI-III system is an infra-red adaptive optics system designed as a semi-common user instrument for use at the Ground-based High Resolution Imaging Laboratory (GHRIL) on the William Herschel Telescope (WHT). The optical layout of the system is shown in figure 1. Light from the Nasmyth focus of the WHT is incident on a six element adaptive mirror and is reflected back onto a toroidal mirror which refocuses the light at an off-axis point. Just before this re-imaged focus the light is split by a dichroic beamsplitter and the infra-red light reflected into the infra-red camera (WHIRCAM) arm. The visible light is passed to the wavefront sensing arm where it passes through a selectable sub-aperture mask and is imaged onto the wavefront sensor (an Astromed CCD15-11 camera) by a split lens assembly. The elements of this split lens are adjustable and these are used to align the images formed by each sub-aperture in a row on a 24x4 pixel region in the corner of the wavefront sensor’s CCD chip, each spot being centred on a 4x4 pixel square. On readout the 4x4 pixels are on-chip binned into a 2x2 quad-cell, the output of which is used to calculate the X and Y wavefront slopes. The system is designed to work in two modes, one an ‘unco-phased’ mode where the mirror segments are just controlled to remove the individual wavefront tip-tilt across each segment but no attempt is made to piston the six mirrors. The other a ‘co-phased’ mode where the segment slopes are used to reconstruct the piston values of each wavefront segment. The real-time reconstruction and control is performed with a Motorola 68020 microprocessor. Pixel scales on WHIRCAM of 0.05, 0.08 and 0.24 arcseconds can be selected giving fields of 12.8, 20.5 and 61.5 arcseconds respectively. A guide star of R-band magnitude 13th or brighter is required to be centred within this field.
2
Ponton, Tony, et Gordon Warnes. « Helicopter IRS Engine Integration for the “FIRST” Technology Demonstrator Programme ». Dans ASME Turbo Expo 2007 : Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27408.
Texte intégralRésumé :
The balanced protection of military assets presents a major challenge to military rotorcraft customers. The proliferation of sophisticated threat systems (including simpler weapons cued by imaging hardware) has highlighted the need for signature suppression systems to be considered as an integral part of rotorcraft design. Suppression of emissions at source offers multiple synergies with other aircraft systems including aerothermal optimisation (minimised pressure losses & highest utility of air flows), enhanced efficiency of other defensive aids equipment, and increased operational effectiveness. The optimisation of the benefits of IR suppression to the helicopter platform as a whole is closely tied into the design of the engine and exhaust system. The achievement of a successful design thus requires the close cooperation of the airframe and engine manufacturers and the availability of the necessary design and assessment tools. This paper is intended to illustrate the many aspects of Infra-Red Suppressor (IRS) design and the tools required to enable successful IRS optimisation and airframe integration. The development of a generic Future Infra-Red Suppressor Technology (FIRST) and the supporting design & analysis capability are described. The FIRST technology development programme has yielded a generic, scaleable, retrofit helicopter IRS that balances aircraft signatures (multi-band IR & RADAR) and installation penalties (such as engine performance and operating costs) to yield a substantial increase in aircraft survivability when compared with existing IRS designs.
3
Cushing, David. « Bandpass Filters for Communications ». Dans Optical Interference Coatings. Washington, D.C. : Optica Publishing Group, 1995. http://dx.doi.org/10.1364/oic.1995.fa4.
Texte intégralRésumé :
There is considerable interest today for filters for fiber optics telecommunications are in the Near Infra-red spectral area. Activity is centered about 1550 nm. Components for Wavelength Division Multiplexer filters used with fiber amplifiers require very high transmission of certain selected wavelengths with very low transmission of an adjacent wavelength in the band of 1530 to 1580 nm. Lasers for this spectral area have a high degree of wavelength variability with operating environments and also with aging. The bandwidth of the filter is specified to pass the signal over a wide range of conditions. Ripple in the passband must also be controlled to meet stringent customer demands. The number of cavities in the filter is determined by the requirements for isolation of allowed wavelengths of the other channel(s).
4
Camci, C., G. Glezer, J. M. Owen, R. G. Pilbrow et B. J. Syson. « Application of Thermochromic Liquid Crystal to Rotating Surfaces ». Dans ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-138.
Texte intégralRésumé :
Encapsulated thermochromic liquid crystal (TLC) can be used to measure the surface temperature of stationary or rotating bodies. However, some research workers have reported a “rotational shift”; when the temperature of a rotating body is measured by thermocouples and TLC, there is a difference between the two sets of temperatures, and this difference increases with increasing rotational speed. Two research groups (Camci and Glezer in the USA, and Owen, Pilbrow and Syson in the UK) have independently examined the effect of speed on TLC applied to the surfaces of rotating disks. The USA group used narrow-band TLC on a disk of 305-mm diameter rotating up to 7500 rev/min, measuring the surface temperature using an infra-red (IR) sensor. The UK group used wide-band TLC on a disk of 580-mm diameter rotating up to 7000 rev/min, measuring the temperature with an IR thermal imager. Both groups used the so-called hue technique to evaluate the temperature of the TLC and concluded that, even for centripetal accelerations in excess of 104g, there is no significant effect of rotational speed on either narrow-band or wide-band TLC. It is suggested that the “rotational shift” observed by some researchers was probably caused by thermal-disturbance errors, which affected the thermocouples, rather than by changes in the TLC.
5
Niu, Baohua, Grace Mei Ee Khoo, Yuan-Chuan Steven Chen, Fernando Chapman, Dan Bockelman et Tom Tong. « Laser Logic State Imaging (LLSI) ». Dans ISTFA 2014. ASM International, 2014. http://dx.doi.org/10.31399/asm.cp.istfa2014p0065.
Texte intégralRésumé :
Abstract Logic State Imaging (LSI) using Infra-Red Emission Microscopy (IREM) [1-4] has been an indispensable technology for silicon CMOS process development and product debug applications. Its main limitations are relatively poor spatial resolution due to the broadband near-infrared photons emitted, and poor Signal to Noise Ratio (SNR) with low voltage and low leakage processes and products. Continuous-Wave Laser Scanning Microscope (CW-LSM) based Signal Imaging and Probing (CW-SIP) [5-9] technology is also widely used. It features inherently better spatial resolution than IREM, due to the use of monochromatic 1319nm or 1064nm laser light, and high SNR due to its weaker dependence on voltage and leakage, and, for signal imaging applications, the use of narrow band detection to reduce noise. However, CW-SIP can only detect modulating signals, so it couldn’t previously be applied to LSI. In this paper, we introduce an innovative approach that overcomes this limitation to enable Laser Logic State Imaging (LLSI). Actual fault isolation and design debug cases using this technology are presented to show its advantages in terms of resolution (>50% better), SNR (>2X better) and throughput time improvement, especially at low voltages (down to 500mV).
6
Perera, D. S., E. R. Vance, Z. Aly, K. S. Finnie, J. V. Hanna, C. L. Nicholson, R. L. Trautman et M. W. A. Stewart. « Characterisation of Geopolymers for the Immobilisation of Intermediate Level Waste ». Dans ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4589.
Texte intégralRésumé :
Geopolymers are made by adding aluminosilicates to concentrated alkali solutions for dissolution and subsequent polymerisation to take place. Their physical behaviour is similar to that of Portland cement and they have been considered as a possible improvement on cement for several applications including as media for the encapsulation of hazardous or low/intermediate level radioactive waste. We studied in detail a commercial geopolymer to try to get a better understanding of geopolymers in order to enhance its leach resistance for immobilisation of intermediate level radioactive waste. We also briefly investigated two types of experimental geopolymers, one made with a metakaolinite and another from fly ash as the aluminosilicate source. The commercial geopolymer paste had an apparent porosity of 26% and it was possible to reduce it to 17% by adding ∼ 30 weight % foundry sand. The apparent porosities of the geopolymer made from metakaolinite and from fly ash were 13% and 26% respectively. X-ray powder diffraction showed in the three geopolymers, an amorphous phase (deduced by the presence of a very broad diffuse peak centred at a d-spacing of ∼ 0.32 nm), quartz and other minor phases. The energy dispersive spectroscopic analysis under the scanning electron microscope confirmed these. Magic angle spinning nuclear magnetic resonance data from the samples showed Al to be mainly in 4-fold coordination and Si sites varying from Q0 to Q4 coordination as also found by other researchers. 23Na spectra indicated that the Na was mainly in the pore water. The 133 Cs spectra showed a strong possibility of Cs being mainly bound in the structure while a small amount could still be in the pore water. The initial leach tests showed alkalis were leached out at rates of several orders of magnitude more than the Al and Si network ions. The most likely reason is that a significant alkali inventory is in the pore water. To remove pore water and incorporate simulated radionuclides such as Cs in the network the commercial geopolymer was heated up to 1200°C. Differential thermal/thermogravimetric analysis showed the loss of water occurs in three stages and most had been lost by 700°C. These results are in broad agreement with the Infra red spectra obtained for samples heated over the temperature range 30–900°C. The broad water band intensity in the range 2600-30-900°C. The broad water band intensity in the range 2600–3800 cm −1 decreased steadily with temperature although a small fraction remained even after heating to 500°C. The silanol band had disappeared at 800°C, and the 3619 cm−1 band (due to OH) virtually disappeared by 900°C.
7
Zevenhoven, Ron, et Martin Fa¨lt. « Heat Flow Control and Energy Recovery Using CO2 in Double Glass Arrangements ». Dans ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90189.
Texte intégralRésumé :
The interaction of gases such as carbon dioxide (CO2) and other so-called participating gases with thermal infra-red (TIR) radiation is one of the mechanisms behind global warming and climate change. The noticeable effect this apparently gives at atmospheric concentrations of around 400 ppmv can be made use of in technical systems where pure (and pressurized) CO2 is confined in, for example, a double glass arrangement. Depending on pressure, temperature, gas composition and path length a certain “optical thickness” for TIR radiation is obtained that can be used to decrease or increase heat flows, or create temperature differences. The latter would allow for power production using, for example, a Stirling engine. Of great importance also is the temperature difference between ground-level surroundings and the sky. With significant amounts of electric power being used for air-conditioning, heating or cooling purposes a smart window set-up that makes use of the interference of TIR radiation with participating gases may result in significant reductions in energy use and costs. Typical applications can be found in residential and office building windows or a glass roof that covers large building structures like railway stations or parking areas. Besides glass, plastics may be used as window material. The purpose of this paper is to present the potential of energy recovery from TIR radiation using most importantly earth-to-space radiation of long wavelengths (> 4 μm), to be distinguished from incoming solar radiation at shorter wavelengths (< 4 μm). Most relevant here is the TIR absorption band for CO2 around a wavelength of 15 μm. Note also that unlike solar irradiation the earth-to-space radiation is not limited to daytime and cloudless skies. Finally, some examples for technical system lay-out and performance are given. This gives an introduction by the paper by Fa¨lt and Zevenhoven submitted to this conference (Fa¨lt and Zevenhoven, 2010).