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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Kryptoanalytické útoky na lehkovážné šifry / Cryptanalytic attacks on lightweight ciphers

Rabas, Tomáš January 2021 (has links)
In 2016 the National Institute of Standards and Technology (NIST) started the stan- dardization process for lightweight cryptography (LWC). We provide a broad introduc- tion to lightweight cryptography together with a survey of current design trends and lightweight cryptography standards, with special attention to this competition. In the second part, we present a description and cryptoanalysis of three lightweight ciphers: SIV-Rijndael256, CLX, and Limdolen. 1
2

Efficiency of Fluorescent Whitening Agents in Pigment Coatings / Efficiency of Optical Brightening Agents in Pigment Coatings

Aman, Zaeem January 2012 (has links)
The objective of this work was to study the addition of fluorescent whitening agents (FWAs) for efficient use on pigment coating of paper substrates with low grammage and the goal was to achieve high optical response by using low amount of FWAs. A commercial light-weight coated (LWC) paper grade was provided by Stora Enso Corbehem Mill and isotropic laboratory sheets were produced at Stora Enso Research Centre using PFI sheet former. Optical properties such as brightness, whiteness and L, a* and b* colour space values were evaluated using Minolta spectrophotometer with D65 illuminant for both types of substrate using different types and amounts of FWA while the effect of the addition of dye was evaluated in both isotropic sheets and as well as in the coating. The results showed that brightness and whiteness of double-coated paper increased by increasing the amount of fluorescent whitening agent in the coating layer. Also, higher brightness and whiteness was achieved by introducing a higher amount of fluorescent whitening agent in the top coating rather than in a pre-coating. The addition of a shading colorant in the paper substrate had a positive influence not only on the brightness but also on the whiteness of coated paper. / Syftet med denna studie var att studera tillsatsen av fluorescerande vitmedel (FWA) för att effektivisera användningen i pigmentbestrykning av papper med låg ytvikt. Målet var att nå en hög optisk respons men ändå använda en låg mängd FWA. Ett kommersiellt LWC-papper erhölls från Stora Enso, Corbehems pappersbruk, och isotropa laboratorieark tillverkades med PFI-arkformerare på Stora Enso Research Centre. Optiska egenskaper, såsom ljushet, vithet och färgrymd (L, a* och b* värden), hos samtliga prover med varierande mängd och typ av FWA uppmättes med hjälp av en Minolta spektrofotometer med D65 ljuskälla. Effekten av färgnyanstillsats utvärderades både hos handgjorda ark och hos bestrykningslager. Resultaten visade att både ljushet och vithet hos dubbelbestrukna ark ökade med ökad mängd FWA i bestrykningslagren. Högre ljushet och vithet nåddes också när FWA placerades i toppbestrykningen. Tillsats av nyanseringsfärg i papperssubstratet ökade både ljushet och vithet hos de bestrukna arken.
3

Etude du dépôt de radionucléides par les gouttelettes de brouillards et de nuages sur les végétaux à partir d'expérimentations in situ / Deposition of radionuclides on plants by fog and cloud droplets

Tav, Jackie 12 October 2017 (has links)
Pour les besoins du refroidissement de leurs réacteurs, les CNPE1 sont placés à proximité immédiate de cours d’eau ou du littoral. Ils sont de ce fait exposés à des bancs de brouillards, en particulier à l’automne et au cours de l’hiver. Or les modèles opérationnels de dispersion atmosphérique/dépôt, utilisés pour simuler la contamination radioactive de l’environnement à la suite d’un accident nucléaire, considèrent uniquement les dépôts par temps sec et ceux par temps de pluie. Faut-il tenir compte de la présence des brouillards comme terme additionnel de dépôt de radionucléides en cas d’accident nucléaire ? Pour répondre à cette question, une étude expérimentale a été conduite sur plusieurs sites exposés aux brouillards ou aux nuages (principalement la plateforme d’observation atmosphérique de l’ANDRA à Houdelaincourt ainsi que la station de recherche atmosphérique de l’OPGC/CNRS2 au sommet du Puy de Dôme et la plateforme d’étude atmosphérique SIRTA3 de l’IPSL4 à Palaiseau). La collecte d’eau de brouillard et la mesure des quantités d’eau déposées sous forme de gouttelettes sur différents types de végétaux, ont été réalisées respectivement grâce à collecteurs à fils et des pesées de précision. En mesurant le contenu en eau liquide dans l’air ainsi que la masse d’eau déposé sur les plantes, il a été possible de calculer des vitesses de dépôt des gouttelettes de brouillard pouvant atteindre plusieurs dizaines de cm.s-1 dans le cas d’un brouillard composé de grosses gouttelettes (diamètre médian volumique moyen de 20 µm). Ces vitesses élevées mettent en évidence l’importance des processus gravitationnels mais aussi turbulents notamment dans le cadre du dépôt sur des végétaux à structure foliaire tridimensionnelle comme les conifères. L’effet d’auto-écrantage lié à une densité de biomasse foliaire élevée a également été quantifié. Les concentrations en radionucléides à l’état de traces ont montré que l’eau de brouillard pouvait être jusqu’à 20 fois plus concentrée que l’eau de pluie, du fait de la dilution par condensation de vapeur d’eau sur les gouttelettes au cours de leur grossissement. Les mesures des masses d’eau déposées par les brouillards et de la concentration en radionucléides dans les gouttelettes sur le site d’Houdelaincourt, permettent d’estimer ces dépôts habituellement qualifiés d’occultes car trop faibles pour être quantifiés par des pluviomètres ou des radars météorologiques. Sur l’ensemble d’une saison de brouillard, le dépôt occulte de radionucléides a représenté jusqu’à 25% des dépôts par temps secs et par temps de pluie. En cas de rejet accidentel, la présence de brouillard pourrait contribuer à hauteur de 14% du dépôt par temps sec. Ces résultats mettent en évidence la nécessité de prendre en compte ce processus de dépôt pour mieux quantifier les retombées radioactives sur des territoires en contact avec des brouillards ou des nuages (en ce qui concerne les sites d’altitudes), en particulier en situation post-accidentelle. Un schéma simple de type dépôt sec, considérant le diamètre médian des gouttelettes dérivé de la visibilité, permet à minima de mieux simuler le processus de dépôt par sédimentation des gouttelettes. Ces travaux restent à compléter pour quantifier la contribution de la turbulence induite par l’écoulement de l’air au voisinage des obstacles comme des végétaux de grandes tailles et incorporer un schéma spécifique dans les modèles de dépôt. / For the purpose of cooling off their reactors, nuclear power plants are located near rivers, ponds or in coastal areas. In temperate regions and during fall and winter, they are frequently exposed to fogs. Operational models of atmospheric dispersion and deposition used to estimate radioactive contamination of the environment after a nuclear accident, consider dry deposition and wet deposition by rain. Should we take into account the deposition by fog droplets as an additional process in term of deposition? To answer this question, an experimental study has been setup on several sites often exposed to fogs or clouds. Fogwater collection and measurement of fogwater deposited on plants were realized with string collectors and precision balances, respectively. Different plant types were used for this study: small conifers, cabbage, grass plus a bare soil as a reference deposition surface. By measuring the liquid water content (LWC) and the mass of water deposited on plants, fog droplet deposition velocities can be calculated. In the case of fog composed mainly of big droplets (mean median volume diameter of 20 µm), deposition velocities of these droplets can reach several tens cm.s-1. These high deposition velocities highlight the fact that gravitational but also turbulent processes are both contributing to the deposition on plants especially with a tri-dimensional structure such as conifers. The edge effect linked to a strong density of trees has also been identified and quantified during our experiments. The radionuclides found in trace amounts in fogwater showed that fogwater could be up to twenty times more concentrated in radionuclides than rain water. It is due to the activity dilution during the condensation phase of the droplets, when the droplets are growing. Based on measurements of the mass of water deposited by fog and concentrations of radionuclides in fog droplets on the site of Houdelaincourt, occult deposition that cannot be quantify by rain gauges or meteorological radar can be estimated. Over a whole season of fog, occult deposition can represent up to 25% of the total deposition (dry and wet by rain) of radionuclides. In case of an accidental release, fog could contribute to 14% of the total deposition if no rain event occurs. Those results highlight the fact that fog deposition should be considered to better quantify radioactive fallouts in areas embedded by fog (or clouds for high altitude sites), particularly in post-accident situation. A simple model of dry deposition to simulate the droplets deposition by sedimentation can be developed, using the median diameter of droplets derived from the visibility. This work still needs to be completed to quantify the turbulence contribution induced by the air flow near obstacles such as large plants and to implement a specific scheme into deposition model.
4

Print Quality regarding Advertisements in the Nordic Heatset Printing Industry

Wang, Tao January 2012 (has links)
Accompanied by the fast development of technology and channels in the advertisement industry, many traditional incumbents felt pressure and were seeking ways to change or better their own position within the industry. The Nordic Association of Heatset Printer (NAHP), where this thesis was carried out, is largely associated with these traditional channels for advertising, such like newspapers, brochures and magazines. They are taking their initiative to prepare and face the challenge coming from new entrants within the advertising industry. I have identified that to fulfill the responsibilities to their customers at a very high standard could enable themselves to continuingly remain a competitive position in the advertisement industry, and among these responsibilities, the printing quality is definitely an important one. By checking whether all the printers conform to the error tolerances set by the ISO standard, I could offer the members of the organization useful information and suggestion, and eventually give them directions on where they might need to improve, and where they need to maintain. I have also identified 3 determinants regarding printing and they are print density, dot gain and the ΔE of L*a*b*. Checking whether those three primaries have met the industry standard has become the main job of this thesis work. To finish this thesis work, I have gathered samples from printers within NAHP, tested the color control strips on each samples, input the data into statistical Excel files, programmed to analyze the data, and finally conducted evaluations. The test results have revealed that most presses from the printing houses within my thesis work are able to offer high quality prints. However, certain problems have also been identified. Some presses definitely need to change and improve their printing setting in order to reach ISO standard and achieve audience satisfaction. In addition, the results have also double confirmed that all three investigated properties, print density, dot gain and ΔE of L*a*b*, correlate intensely and influence one and another.
5

Quantifying the Environmental Performance of a Stream Habitat Improvement Project

Morse, Cody 01 August 2018 (has links)
River restoration projects are being installed worldwide to rehabilitate degraded river habitat. Many of these projects focus on stream habitat improvement (SHI), and an estimated 60%of the 37,000 projects listed in the National River Restoration Science Synthesis Program focus on SHI for salmon and trout species. These projects frequently lack a sufficient monitoring program or account for the environmental costs associated with SHI. The present study used life cycle assessment (LCA) techniques and topographic effectiveness monitoring to quantify environmental costs on the basis of geomorphic change. This methodology was a novel approach to assessing the cost-benefit relationship of SHI. To test this methodology, two phases of the Lower Scotts Creek Floodplain and Habitat Enhancement Project (LSCR) were used as a case study. The LSCR was a SHI project installed along the northern coast of Santa Cruz County, California, USA. A limited scope LCA was used to quantify the life cycle impacts of raw material production, materials transportation, and on-site construction. Once these baseline results were produced, a topographic monitoring program was used to quantify the topographic diversity index (TDI) in pre- and post-project conditions. The TDI percent change was used to scale the baseline LCA results, which quantified the environmental impacts based on geomorphic change. Phase II outperformed phase I. Phase I had greater cumulative environmental impacts and experienced a 7.7 % TDI increase from pre- to post-project conditions. Phase II had 43% less cumulative environmental impacts and experienced a 7.9% TDI increase from pre- to post-project conditions. The impacts in phase I were greater because of the amount of material excavated to create off-channel features, which were a key feature of the LSCR. A scenario analysis also was conducted within the LCA component of this study. The scenario analysis suggests that life cycle impacts could be reduced by 30%-65% by using the accelerated recruitment method in place of importing materials to build large wood complexes. The results of this study suggest that managers may improve the environmental performance of SHI projects by: (1) using the accelerated recruitment method to introduce larger key pieces to the channel, reducing the need to import materials; (2) using nursery grown plants as opposed to excavating plants for revegetation; (3) minimizing fuel combustion in heavy equipment and haul trucks by ensuring clear access to the channel and streambank, using small engine equipment to clear access corridors during site preparation, running more fuel-efficient machinery or bio-fuel powered machinery, and by attempting to minimize haul distances by sourcing materials locally; and (4) utilizing a “franken-log” design (a ballasted LWC configuration with a rootwad fastened to the downstream end of a log) in LWCs which led to favorable TDI change. This study concluded that LCA could be a valuable tool for monitoring SHI and river restoration projects and that further research of the TDI analysis is justified.

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