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Letteratura scientifica selezionata sul tema "Grains de silt"

Autore: Grafiati

Pubblicato: 30 luglio 2022

Ultima modifica: 8 agosto 2022

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Articoli di riviste sul tema "Grains de silt"

Monkul, Mehmet Murat, e Jerry A. Yamamuro. "Influence of silt size and content on liquefaction behavior of sands". Canadian Geotechnical Journal 48, n. 6 (giugno 2011): 931–42. http://dx.doi.org/10.1139/t11-001.

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This study investigates the fines content influence on liquefaction potential of a single base sand mixed with three different essentially nonplastic silts through strain-controlled monotonic undrained triaxial compression tests. Confining stress (30 kPa) and deposition method (dry funnel deposition) were kept the same, while fines content was varied, to solely focus on how different silts and their contents influence the undrained response of the sand under comparable conditions. It was found that if the mean grain diameter ratio (D50-sand/d50-silt) of the sand grains to silt grains is sufficiently small, the liquefaction potential of the sand increases steadily with increasing fines content for the studied range (0%–20%). As D50-sand/d50-silt increases, the liquefaction potential of the silty sand might actually be less than the liquefaction potential of the clean sand. Test results also revealed that commonly used comparison bases (i.e., void ratio, intergranular void ratio, relative density) are not sufficient for assessing the influence of fines on liquefaction potential of silty sands. Finally, relative size of the silt grains should also be considered in geotechnical engineering practice in addition to content and plasticity of fines to characterize the influence of silt on liquefaction potential of sands.

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Catto, N. R. "Hydrodynamic distribution of palynomorphs in a fluvial succession, Yukon". Canadian Journal of Earth Sciences 22, n. 10 (1 ottobre 1985): 1552–56. http://dx.doi.org/10.1139/e85-163.

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Investigation of a sequence of alternating sand and silt deposits formed in an ephemeral braided stream channel adjacent to the modem Caribou River, Yukon, revealed differences in the palynological spectra of the sediment types. Picea, Betula, Alnus, and Gramineae are more concentrated in the silt units, whereas Cyperaceae, Chenopodium, Lycopodium, and Ericaceae are preferentially concentrated in the sand strata. These distribution patterns reflect the hydrodynamic properties of the grains, in addition to environmental differences. Grains of Picea, Betula, and Alnus settle through still water at the same rates as silt-sized quartz particles and are therefore concentrated in the portion of the deposit derived from the stream's suspended load. Thus, increases in percentages of these palynomorphs with decreasing grain size may not reflect vegetation changes or climatic alterations but may be consequences of the hydrodynamic situation.

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Crouvi, Onn, Rivka Amit, Yehouda Enzel, Naomi Porat e Amir Sandler. "Sand dunes as a major proximal dust source for late Pleistocene loess in the Negev Desert, Israel". Quaternary Research 70, n. 2 (settembre 2008): 275–82. http://dx.doi.org/10.1016/j.yqres.2008.04.011.

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AbstractGrain size analyses of three hilltop, primary eolian loess sequences in the Negev desert, southern Israel, show a bimodal grain-size distribution at 50–60 μm and 3–8 μm. Using analyses of mineralogy and OSL ages we demonstrate that the coarse mode is composed mostly of quartz grains and its relative magnitude increases regionally with time, suggesting an enhancement of a time-transgressive proximal dust source compared to a distal, Saharan fine-grain dust. The only proximal dust source for large amount of coarse silt quartz grains is the sands that advanced into Sinai and the Negev concurrently with the loess accretion during the late Pleistocene as a result of the exposure of the Mediterranean shelf. We therefore propose that the coarse silt quartz grains were formed through eolian abrasion within the margins of an advancing sand sea. This relationship between desert sand seas as a source for proximal coarse dust and desert margin loess deposits can be applicable to other worldwide deserts such as Northern Africa, China and Australia.

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Lamirande, I., B. Lauriol, A. E. Lalonde e I. D. Clark. "La production de limon sur des terrasses de cryoplanation dans les monts Richardson, Canada". Canadian Journal of Earth Sciences 36, n. 10 (1 ottobre 1999): 1645–54. http://dx.doi.org/10.1139/e99-072.

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The production of silt on cryoplanation terraces in the Richardson Mountains was documented by a sedimentological study. Geochemical, grain-size, and petrographic analyses of the Jurassic Bug Creek sandstone were done. Results show that in the unaltered rock the detrital quartz grains are solidly held by a siliceous cement. In the altered and strongly altered sandstone, there is a marked increase in intergranular porosity and fracturing of the grains. The disaggregation and weathering of the sandstone releases mainly material in the silt-size fraction, with lesser amounts of sand and clay. This material covers the tread of the terraces and constitutes a potential source of loess in glacial time. Runoff water has a PCO2 value two orders of magnitude greater than the atmosphere yet is weakly mineralized, with only amorphous silica approaching saturation. However, the weathering of sandstones is probably accelerated by the chemical action of water which, by attacking the cement that forms the diagenetic overgrowth of the quartz grains, facilitates their release.

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Jonczak, Jerzy, Marek Degórski e Bogusława Kruczkowska. "Comparing quartz silt surface microstructures in two sandy soils in young-glacial landscape of northern Poland". Soil Science Annual 67, n. 3 (1 settembre 2016): 131–39. http://dx.doi.org/10.1515/ssa-2016-0016.

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AbstractThe studies on quartz silt surface microstructures using scanning electron microscopy (SEM) were performed in Brunic Arenosol and Gleyic Ortsteinic Podzol, as major components of soil cover of the lower supra-flood terrace of the Słupia River, N Poland. Brunic Arenosols have developed from coarse- and medium-grained fluvioglacial sands, whereas Podzols from aeolian sands of mid-Holocene age, which in some places were covered with younger aeolian deposits. A group of at least 100 randomly selected grains from each soil horizon have been analyzed. The grains were classified into one of the following groups: fresh (type A), grains with the features of chemical weathering (type B), grains coated with scaly-grain incrustations (type C), grains coated with bulbous incrustations (type D), and cracked grains (type E). Parent materials of the investigated soils did not differ significantly in terms of contribution of grain types and type C predominated in both soils. Significant differences were noted in soil solums. Grains covered by scaly-grained incrustations predominated in Brunic Arenosol, which constituted 62–89%. In the profile of Gleyic Ortsteinic Podzol grains type B predominated in AE and E horizons (65–82%), whereas in the remaining horizons grains type C (54–77%).

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Delage, Pierre, Martine Audiguier, Yu-Jun Cui e Michael D. Howat. "Microstructure of a compacted silt". Canadian Geotechnical Journal 33, n. 1 (25 marzo 1996): 150–58. http://dx.doi.org/10.1139/t96-030.

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This paper presents a qualitative and quantitative study of the microstructure of a compacted silt, carried out using a scanning electron microscope and mercury intrusion pore size distribution measurements. Samples have been statically compacted at three water contents: on the dry side of the standard Proctor optimum water content, at the optimum, and on the wet side. The wet sample has a matrix type structure, with a clayey fraction filling the voids and adhering to the silt-sized grains, whereas the other samples display a structure characterized by a skeleton made of silt grain aggregates linked together by clayey bidges. The distribution of water and air within the microstructure of the compacted soil is described for each of the three compaction states. Key words: compacted soil, microstructure, scanning electron microscope, pore size distribution, mercury intrusion, clay hydration.

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Ryan, Adrienne L., e Stephen R. Cattle. "Do sand dunes of the lower Lachlan floodplain contain the same dust that produced parna?" Soil Research 44, n. 8 (2006): 769. http://dx.doi.org/10.1071/sr06051.

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Æolian dust deposits are known to be widespread in south-eastern Australia, with the dominant model being that of ‘parna’, an aggregated material comprising clay, calcium carbonate, and silt-sized quartz. Despite a general acceptance of the parna model, there is surprisingly little evidence of silt-sized clay aggregates remaining in parna profiles. To investigate a relatively pure æolian dust deposit within the proposed zone of parna distribution, we examined the various phases of 3 source-bordering sand dunes on the lower Lachlan River floodplain of south-western NSW. In each dune exists an upper-slope phase of coarse brown sand, a mid-slope layer of reddish, clay-enriched sand, and a lower-slope phase of coarse sand dominated by an accumulation of carbonate glaebules. Granulometric analyses of the clay-enriched phase(s) of each dune identified a conspicuous particle population in the 20–60 μm range, and another in the fine-silt/clay range (<10 μm). Mineralogical characterisation revealed an abundance of illite and kaolinite in the upper 2 dune phases, coupled with a minor amount of smectite, further suggesting an allochthonous æolian origin, as the surrounding floodplain is smectite-rich and relatively poor in illite. Micromorphological features within the clay-enriched phase, including abundant argillans and laminar bands of well-sorted fine quartz grains, indicate that this clay is a depositional feature, illuviated from surface horizons and re-deposited at depth. A similar illuvial origin is suggested by the fine crystalline nature of the calcium carbonate accumulation, ubiquitously coating the matrix mineral grains of the lower dune phase. No discrete clay aggregates were identified; however, all the assumed components of parna (silt-sized quartz grains, clay, and calcium carbonate) were identified, spatially separated within each dune. The consistency of these features among the 3 dunes indicates an analogous æolian dust accession, but it is not clear whether the clay component of this dust was transported as coatings on quartz grains, or as silt-sized clay aggregates accompanied by silt-sized quartz grains.

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Setiady, Deny, e Ediar Usman. "MINERAL CONTENT OF SURFICIAL SEDIMENT OF THE RANGSANG ISLAND AND ITS SURROUNDING AREA, MERANTI REGENCY, ARCHIPELAGO RIAU PROVINCE". BULLETIN OF THE MARINE GEOLOGY 30, n. 2 (15 febbraio 2016): 67. http://dx.doi.org/10.32693/bomg.30.2.2015.76.

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According to the regulation No 4 of 2009 of Mineral and Coal Mining Management stated that the requirement of an inventory for mineral resources data was created to support the establishment of mining area. This study is intended to obtain mineral resources content and surficial sediment data, Geographically the study area belongs to Meranti Archipelago Regency, Riau Province. it is located between 102o00'00" - 103o 15'00" E and 00o35'00" - 01o28'00" N. Grain size analyses result show that surficial sediment in the study area consists of silt, silty sand and sand which is dominated by silt. Based on the mineral identification, some of the minerals such as quartz, cassiterite, magnetite, hematite, dolonite, biotite and zircon have been found. Silt distribution is very wide started from estuarine southeast part northen part of Rangsang Island toward southeast of rangsang island. Sandy silt only found at the southeast of Rangsang Island, while sand sediment is found at the south and southeast of Rangsang Island. The presence of silt and sand grains is influenced by moderate to strong currents and wave patterns, so that the silt and sand grains sediment was transported along coastal to offsore area, while the fine grained (clay - silt) are deposited in the valley at the western part of Rangsang Island.Keywords: mineral, surficial sediment, Rangsang Island Berdasarkan Undang Undang Nomor 4 tahun 2009 tentang Pengelolaan Pertambangan Mineral dan Batubara, disebutkan bahwa inventarisasi data sumber daya mineral diperlukan dalam rangka mendukung penetapan Wilayah Pertambangan (WP). Penelitian ini dimaksudkan untuk memperoleh data kandungan sumber daya mineral dan sedimen dasar laut. Daerah penelitian, secara geografis termasuk dalam Kabupaten Kepulauan Meranti, Provinsi Riau, dan terletak pada koordinat antara 102o00'00" - 103o15'00" BT dan 00o35'00" - 01o28'00" LU. Hasil analisis besar butir menunjukkan sedimen permukaan dasar laut di daerah penelitian terdiri atas lanau, lanau pasiran dan pasir yang didominasi oleh lanau. Berdasarkan identifikasi mineral pada sedimen permukaan dasar lautnya menunjukkan kehadiran mineral kasiterit, magnetit, hematit, dolomit, biotit, zirkon dan kuarsa. Penyebaran lanau sangat luas dimulai dari daerah estuari barat laut dan bagian utara Pulau Rangsang, hingga ke sebelah tenggara Pulau Rangsang. Lanau pasiran hanya terdapat di tenggara Pulau rangsang, sedangkan pasir hanya terdapat di daerah di bagian selatan - tenggara Pulau Rangsang. Adanya butiran lanau - pasir dipengaruhi oleh pola arus dan gelombang yang sedang sampai kuat, sehingga butiran berukuran lanau - pasir dapat terangkut ke arah lepas pantai, sedangkan butiran halus (lempung) mengendap di daerah lembah di bagian barat Pulau Rangsang. Kata kunci: mineral, sedimen permukaan dasar laut, Pulau Rangsang

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Davidson, Donald. "Balneaves: Soil Thin Sections". Proceedings of the Prehistoric Society 58, S2 (1992): 23–25. http://dx.doi.org/10.1017/s0079497x00079172.

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1. Structure: partially accommodated channels (0.16 to 0.80mm in width) above the pan; no aggregates; fewer channels below the pan; channel pattern - straight to curved; vughs (spherical to elongate, not normally connected) 0.4 to 0.8mm in diameter and are not orientated and have random pattern: above pan channels and vughs partially connected; pellicular grain microstructure - weakly developed.2. Mineral components: coarse fraction: quartz grains range in size from silt to fine/medium sand (<lmm). One large quartz (200mm). Dominance of single and compound quartz grains; instances of biotite and plagioclase; quartz grains -angular/subangular and smooth. Fine fraction: brown, optically amorphous iron oxides, isotropic.

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Velbel, Michael. "Phoenix first to see silt grains on Mars". Nature 481, n. 7379 (gennaio 2012): 29. http://dx.doi.org/10.1038/481029c.

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Più fonti

Tesi sul tema "Grains de silt"

Saur, Hugo. "Étude des microstructures par tomographie à rayons X : application aux roches clastiques à grain fin". Electronic Thesis or Diss., Pau, 2022. http://www.theses.fr/2022PAUU3005.

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L’étude de la microstructure des roches est indispensable pour nos enjeux contemporains et futurs en matière d'énergie, d’ingénierie et de construction. D’autre part, cette étude permet de caractériser les processus de déformation géologique ayant conduit à l’état actuel des unités lithologiques. Les roches clastiques à grain fin, communément appelées "shales" en anglais, représentent environ deux-tiers de l’ensemble des roches sédimentaires. Les données 3D relatives aux grains de silt ou clastes inclus dans la matrice argileuse et poreuse de ce type de roche sont peu fréquentes. Ces données sont pourtant cruciales pour comprendre les propriétés anisotropes à l’échelle macroscopique mais aussi pour évaluer l’état de déformation de la matrice rocheuse. Mieux connaitre la microstructure de ces roches permettrait d’être prédictif quant à leurs propriétés mécaniques ou physiques indispensables pour les applications du secteur de l’énergie par exemple. La tomographie à rayons X (XCT) est une technique non destructive permettant d’obtenir une image 3D de la microstructure d'un objet. Une caractérisation géométrique directe des constituants des roches clastiques à grain fin est envisageable grâce à cette technique. Sur la base d'images XCT, cette thèse vise d’abord à développer des aspects méthodologiques pour étudier la fabrique de forme 3D des clastes ainsi que leur distribution spatiale. Ces aspects sont élaborés à partir de la méthode des moments d’inertie qui est appliquée sur les grains segmentés des images 3D numériques. Nous présentons ensuite des applications sur des roches à grain fin possédant une fabrique sédimentaire et sur des roches à grain fin déformées présentant une fabrique d’origine tectonique. Le premier volet applicatif de la thèse s’intéresse à une même unité lithologique ayant enregistrée différentes quantités de déformation. Des échantillons du bassin sud-pyrénéen et des échantillons issus d’un affleurement historique dans les Appalaches centrales ont été collectés. Nous apportons de nouvelles données sur l’évolution de la forme 3D des grains et des pores à l’échelle micrométrique et sur leur agencement dans la matrice rocheuse en fonction de la déformation. Les données obtenues permettent de discuter des mécanismes de déformation à l’échelle du grain des différentes phases minéralogiques. Cependant, la petite taille des échantillons imagés par XCT (≤ 2 mm de diamètre) soulève la question de la représentativité de ces analyses. Sur le chantier sud-pyrénéen, certains échantillons sont étudiés de manière plus approfondie pour vérifier l’homogénéité des résultats. Nous y montrons que les données XCT complètent les mesures indirectes pétrophysiques en permettant de décrire et de localiser les sous-fabriques intégrées dans une mesure globale de la fabrique. Les limites apparaissent lorsque la dimension caractéristique des structures de déformation avoisine la taille de l'échantillon imagé par XCT. Dans le second volet applicatif, des échantillons provenant de systèmes turbiditiques du bassin sud-pyrénéen sont analysés. Ces systèmes, lorsque déformés en tectonique compressive, présentent l’avantage d’enregistrer la même quantité de raccourcissement différemment exprimée dans les unités lithologiques qui les constituent. Les résultats obtenus à partir de la forme des clastes sont comparés à nos mesures magnétiques globales de la fabrique et montrent une bonne cohérence. La méthodologie présentée dans ce travail peut s’étendre à d'autres types de milieux poreux et granulaires pour une meilleure compréhension de l'influence de l'anisotropie structurale sur leurs propriétés macroscopiques et leur comportement mécanique
The study of the microstructure of rocks is essential for our contemporary and future challenges in energy, engineering and construction. Furthermore, this study allows us to characterize the geological deformation processes that led to the current state of geological formations. Fine-grained clastic rocks, commonly called "shales", represent about two-thirds of all sedimentary rocks. 3D data concerning silt-sized grains or clasts embedded in the porous clay-rich matrix of this type of rock are relatively scarce despite the fact that these data are crucial to understand the anisotropic properties of these rocks at the macroscale but also to evaluate the deformation state of the rock matrix. A better understanding of the microstructure of these rocks would allow us to predict their mechanical or physical properties, which are essential for applications in the energy sector, among others. X-ray computed tomography (XCT) is a non-destructive technique providing a 3D image of the microstructure of any object. A direct geometric characterization of the constituents of fine-grained clastic rocks is possible with this technique. Based on XCT images, this thesis aims first to develop methodological aspects to study the 3D shape fabric of silt particles and their spatial distribution. The moments of inertia of segmented grains from 3D digital images are used for this development. We then present applications on fine-grained rocks with a sedimentary fabric and on deformed fine-grained rocks with a tectonic fabric. The first application part of the thesis focuses on the same lithologic unit having experienced different amounts of deformation. Samples from the South Pyrenean Basin and samples from a historical outcrop in the Central Appalachians were collected. We provide new data on the evolution of the 3D shape of grains and pores at the micrometer scale and their arrangement in the rock matrix with respect to the deformation intensity. The obtained data allow discussing the deformation mechanisms at the grain scale of the different mineralogical phases. However, the limited size of the imaged samples by means of XCT (≤ 2 mm diameter) raises the question of the representativeness of these analyses. On the South Pyrenean site, some samples are studied in more detail to evaluate the homogeneity of the results. We show that the XCT data complement the indirect petrophysical measurements by providing access to localized sub-fabrics that are integrated in a bulk measurement of the rock fabric. The limits are reached when the characteristic length of the deformation structures are on the order of the sample size imaged by XCT. In the second application part, samples from turbiditic systems of the South Pyrenean basin are analyzed. These systems, when deformed in compressive tectonic settings, record the same amount of shortening differently expressed in the various siliciclastic matrices. The results obtained from the shape data of the clasts are compared to our bulk magnetic fabric measurements and show a good consistency. The methodology presented in this work can be extended to other types of porous and granular media for a better understanding of the influence of fabric anisotropy on their macroscopic properties and mechanical behavior

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Van, der Merwe Mathys Johannes Nicolaas. "Determinants of the supply-side fragmentation of maize storage in the North Western Free State production area / Mathys Johannes Nicolaas van der Merwe". Thesis, North-West University, 2012. http://hdl.handle.net/10394/9228.

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For decades commercial silos in South Africa was the only option in which maize could be delivered and sold. After deregulation in the late 1990s commercial silo owners came to face the challenge of alternative storage solutions and loss of market share. The reasons are determined for a shift from commercial storage to on-farm storage. The extent to which on-farm storage will change the current maize storage industry is discussed. The study commences by describing the birth and rapid growth of maize production in South Africa. Soon after maize became a major role-player in the export industry, it was characterised by regulation. The rationale why the market was regulated and how it influenced grain storage is explained. The deregulation process and the objectives of the new Marketing of Agricultural Products Act, No. 47 of 1996, are paraphrased. In the deregulated market, current and future, maize prices are determined by supply and demand. Incentives for storage emerged and cheaper substitutes with various other advantages began to propose alternative storage solutions to farmers. These concurrences of circumstances then lead to fragmentation of grain storage in South Africa. As a relatively young free market, the maize value chain is described to illustrate the position of each role-player in relation to the silo owner. The new price determination factors, price movement rationale and the use of market instruments are subsequently explained. Naturally, a critical assessment of the main different storage solutions available for farmers, are investigated next. Fragmentation is defined and discussed in terms of market equilibrium. A comparison is drawn between the South African and the Australian as well as the US maize storage industry. The empirical research was conducted on two sample groups of farmers in the Free State. The first group is farmers that already make use of an on-farm storage facility. The second group is farmers that annually produce more than 5000 tons of maize and currently do not make use of an on-farm storage facility. Seven important reasons for an on-farm storage facility are determined in the literature study as well as a qualitative study that preceded the quantitative study. Respondents are asked to rank the reasons in order of, in their opinion, importance. A generalized profile of a respondent in each sample group was compiled. Hereafter the outcome of the reasons ranked by both sample groups is discussed. It appeared that Flexible Marketing Option was the most important reason for farmers that already make use of on-farm storage. Farmers did not indicate that Handling and Storage costs are the most important reason why they would invest in an on-farm storage facility. Correlations are drawn between groups and the significance of differences is determined. It is concluded that on-farm storage is sustainable and there will be an increase of the phenomenon over the next three years. Recommendations are given for commercial silo owners to regain market share. Costs analyses and effective cost management along with the promotion that marketing options are just as flexible within commercial silos, as it is outside, are some of the recommendations made.
Thesis (MBA)--North-West University, Potchefstroom Campus, 2013.

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Percier, Baptiste. "Dynamique d'un empilement granulaire : instabilité de tôle ondulée et fluage d'une colonne de grains". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00857243.

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Au cours de cette thèse expérimentale et numérique nous avons étudié le comportement d'un empilement de grains dans deux situations différentes. Dans une première partie, une piste en sable est soumise au passage répété de véhicules, sous certaines conditions un motif régulier de rides apparaît spontanément : c'est l'instabilité de tôle ondulée. Ce phénomène, très répandu sur les routes en terre ou en gravier, est bien sûr très gênant pour les automobilistes mais est aussi très dangereux à cause des pertes d'adhérence qu'il provoque. Nous avons alors reproduit ce phénomène à l'échelle du laboratoire et également dans des simulations numériques de dynamique moléculaire de sphères molles. Grâce à ces outils expérimentaux et numériques nous avons pu mettre en évidence certaines propriétés de l'instabilité. Nous avons notamment mesuré la relation de dispersion des rides et mis en évidence que ce phénomène suit une instabilité de type fourche super-critique. En mesurant les contraintes agissant sur le véhicule nous avons alors pu construire une analyse de stabilité linéaire prédisant quantitativement le seuil de l'instabilité ainsi que la longueur d'onde du motif. Enfin, nous avons étudié des cas plus complexes où différents véhicules circulaient simultanément sur la piste. Nous avons également considéré des cas où la piste était humide et donc cohésive. Dans une seconde partie, nous avons étudié le comportement d'un silo rempli de grains soumis à des variations de température. On observe alors un lent fluage de la colonne que nous avons caractérisé. Deux régimes de fluage sont observés selon l'amplitude des cycles de température et nous avons obtenu une expression de la température critique séparant les deux régimes en fonction des paramètres microscopiques des grains (élasticité et rugosité de surface). Nous avons également étudié le mouvement individuel de chaque grain afin d'interpréter la dynamique macroscopique de l'empilement.

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Kathem, Ali, Tajdar Hussain e Arman Kamali. "Compression perpendicular to grain in timber – Bearing strength for a sill plate". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-36010.

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Timber is widely used in the construction industry, because of its availability and good properties. The compressive strength perpendicular to grain (bearing strength) is one property of wood which is important for structural design. The bearing strength is important for the behavior of the structure in all contact points between wooden members. The calculations models for bearing strength have been a subject of discussion for many years and the different building codes in Europe has treated it differently during the years. The aim of this thesis was to compare different calculations models for bearing strength with the results of an experimental study. In this study the bearing strength for a fully supported beam loaded with a point load was studied. Two different loading lengths were studied as well as loading in a point in the middle of the beam, at the edge of the beam and at a distance of 10 mm between the edge and the loading point. The loading was made with a steel stud. Calculations were also performed according to the following standards; Eurocode 5 (EN1995-1-1:2004) before and after amendment, the German Code (DIN 1052:2004), the Italian Code (CNR-DT 206:2006) and two versions of the Swedish Code (BKR). The results showed that the results from the new version of Eurocode 5 agreed best with the experimental results. The tested results, however, were lower than the values calculated using Eurocode (and all the other codes); this might be explained by the hard loading conditions using a steel stud instead of a wood stud.

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Chilton, Kristin Danielle. "Terrigenous Grain-Size Record of the Newfoundland Ridge Contourite Drift, IODP Site U1411: The First Physical Proxy Record of North Atlantic Abyssal Current Intensity during the Eocene-Oligocene Transition". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/83539.

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Atlantic Meridional Overturning Circulation (AMOC) is a vital process that transfers heat and nutrients throughout the world's oceans, helping to regulate global climate and support marine ecosystems. The timing and nature of the shift to modern AMOC, and especially to deep-water formation in the North Atlantic, has been a topic of ongoing study, with the Eocene-Oligocene Transition (EOT, ~34 Ma) as a potential focal point of this shift. However, the role played by abrupt EOT cooling and Antarctic glaciation in North Atlantic circulation remains unclear. Improved constraints on Paleogene circulation will provide insight into the sensitivity of AMOC to perturbations in global climate, which is particularly relevant in light of contemporary climate change. To examine deep North Atlantic circulation response to the EOT we obtained grain-size data from the terrigenous fraction of the mud-dominated sediments of the Southeast Newfoundland Ridge contourite drift complex at IODP Site U1411, which is interpreted to have formed under the influence of the Deep Western Boundary Current. We analyzed 195 samples that span 150 m of stratigraphy from 36-26 Ma. The main objective was to use the 'sortable silt' fraction (10-63 µm) to generate a record of relative change in bottom-current intensity. These data are complemented with a record of the abundance and size of lithogenic sand (>63 µm). Here we present the first physical proxy record of abyssal current intensity in the North Atlantic, from late Eocene to mid Oligocene. Invigoration of North Atlantic deep circulation occurred gradually (over Myr timescales), with no significant changes linked temporally to the EOT. We infer that deep circulation in the North Atlantic was not sensitive to the abrupt global cooling and Antarctic glaciation associated with the EOT. Rather, our data suggest that changes in North Atlantic circulation were likely governed by longer-term processes related to the opening of key tectonic gateways, such as the Greenland-Scotland Ridge in the North Atlantic, and the Drake and Tasman Passages in the Southern Ocean. Additionally, we identify a significant mid-Oligocene invigoration of North Atlantic abyssal circulation, which climaxes around 27.9 Ma, and is coeval with a decrease in atmospheric CO2.
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Ivánková, Markéta. "Sdružené ocelové zásobníky". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227816.

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Item of diploma thesis is project of steel construction with 6 steel silos for storage the grain. The construction is situated inside hall. Silos are high 24 meter and diameter is 6 meter. The load-bearing steel structure for silos is designed in a variant solution. Silos are assessed by ČSN 73 5570 and ČSN EN 1991-4

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Zou, Zhenhai. "Etude de l'éjection de grains hors d'un cylindre pressurisé". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0412.

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Nous considérons un scénario hypothétique d’accident initié par une insertion de réactivité nucléaire entrainant la rupture de la gaine d’un crayon combustible. La violence du contact avec le fluide caloporteur dépendrait fortement du débit de fragment combustible, initialement confiné avec un gaz pressurisé, sortant du crayon. Ce travail de thèse a consisté à étudier cette dynamique en la modélisant par la vidange d’un milieu granulaire hors d’un silo pressurisé. Nous nous sommes d’abord concentrés sur le rôle de la géométrie interne du silo grâce à un fond incliné. Pour un faible angle d’inclinaison, l’orientation de l’écoulement granulaire (donc le débit) est contrôlée par la friction pariétale, tandis qu’une grande inclinaison détermine cette orientation. Nous nous sommes ensuite intéressés au rôle du gaz pressurisé d’abord en imposant une surpression d’air constante puis en considérant un cas transitoire dans lequel une surpression initiale provoque la rupture de l’orifice. Dans les deux configurations, le débit granulaire est mis à l’échelle par une loi de Beverloo modifiée où le gradient de pression du gaz près de l’orifice agit comme une force motrice supplémentaire qui peut être décrite par la loi de Forchheimer. Nous proposons un modèle quasi-stationnaire pour le débit granulaire ainsi qu’une simulation continue basée sur un modèle multiphasique qui reproduisent bien les résultats expérimentaux. A forts débits, nous observons une instabilité du jet, initiée par des oscillations de pression à l’orifice. Enfin nous avons montré que le milieu environnant agit sur la condition de pression à la sortie du silo
We consider a hypothetical scenario of reactivity initiated accident in a nuclear power plant. The violence of the so-called fuel-coolant interaction phenomena depends strongly on the flow rate of particles out of the gas pressurized rod. The aim of this thesis was to study how this discharge rate is driven by the internal geometry and the pressurized gas. We focused firstly on the discharge of a rectangular silo with an inclined bottom. For a small inclination angle, the granular flow orientation is controlled by the wall friction, whereas a large inclination angle fully determines this orientation. Secondly, we focused on two configurations with pressurized gas : a case with constant gas overpressure at the top of the silo and a more transient case for which an initial larger overpressure initiates the rupture of an orifice. The granular flow rate increases significantly with the gas flow, especially for the finer particles and the large overpressures. In both cases, the flow rate scales with a modified Beverloo law where the gas pressure gradient near the outlet acts as an additional driving force. The pressure gradient is well described by a Forchheimer resistance law through the granular medium. We therefore propose a quasi-steady model for the transient description of the granular flow rate. The two configurations were successfully reproduced by numerical simulations based on a continuum multiphase model. For the larger flow rates, instabilities of the granular jet were found to be initiated by pressure oscillations in the outlet region. The presence of water surrounding the silo only acts through an additional hydrostatic pressure effect

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Ben, Moussa Hocine. "Etude des transferts de chaleur et de masse dans un silo à grains soumis à un flux de chaleur pariétal instationnaire". Poitiers, 1989. http://www.theses.fr/1989POIT2313.

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Le present memoire propose une etude experimentale des transferts de chaleur et de masse dans un silo a grains soumis a un flux de chaleur parietal instationnaire. Les travaux ont ete conduits sur une maquette cylindrique, metallique, de diametre 40 cm et de hauteur 2 m, ouverte a ses extremites inferieure et superieure et contenant des billes d'argile expansee humidifiees qui simulent le grain. Dans une premiere partie on s'interesse a l'obtention experimentale des cinetiques de sechage pour bien caracteriser le materiau de simulation et rechercher la limite de validite de ces cinetiques en presence d'une variation brusque de temperature. Dans une deuxieme partie nous avons modelise et etudie experimentalement l'influence de la convection naturelle sur le sechage d'une masse de grain. L'ecriture du systeme d'equations adimensionnelles permet de mettre en evidence les nombres qui gouvernent le probleme. La determination experimentale du champ de temperature permet de remonter a celui de la vitesse de convection naturelle. La convection massique reste du second ordre devant la convection thermique. Le sechage du grain s'effectue progressivement des parois vers le centre et du bas vers le haut suivant un front determine par la vitesse de convection naturelle. La quantite d'eau evaporee est une fonction du flux applique a la paroi et de la duree d'application. L'experience effectuee justifie parfaitement les previsions que l'on peut faire en utilisant les nombres adimensionnels resultant de l'analyse des equations de transferts

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Vieira, João Alves. "Arquiteturas do trigo: espaços de silagem no Alentejo, do século XIX à atualidade". Master's thesis, Universidade de Évora, 2016. http://hdl.handle.net/10174/19745.

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O presente trabalho de investigação apresenta um estudo sistemático da expressão arquitetónica que teve na região do Alentejo a implantação agro-industrial da cultura do trigo, em especial, durante a "Campanha do Trigo", iniciada em 1929 e prosseguida durante o Estado Novo, até 1969. Para tanto, procede ao mapeamento dos elementos edificados, em ligação com os processos de produção, silagem e moagem industrial do trigo, bem como ao seu transporte, estabelecendo uma análise comparativa com outras regiões e países, com o intuito de revelar o impacto destes equipamentos nos diversos territórios e paisagens. Assim, procura-se compreender as relações que se estabeleceram entre a forma arquitetónica do silo (cujo desenho resulta fundamentalmente de uma resposta programática intrinsecamente ligada à sua função primordial - armazenamento do cereal) e os lugares, onde se implantaram e com os quais se procuraram articular, e as paisagens, com as quais perspetivaram dialogar. Para tal, procede-se a descrição do estado atual de cada exemplar das denominadas "arquiteturas do trigo", com o objetivo de gerar, num primeiro nível, o entendimento de cada caso em particular e, posteriormente, estabelecer, por efeito de comparação, um confronto, quer entre os diferentes contextos em que se inserem, quer entre as suas caraterísticas formais, de modo a tirar ilações que possibilitem problematizar o seu uso futuro, equacionando diferentes perspetivas de atuação sobre o edificado. Finalmente procura-se introduzir uma discussão segundo diferentes orientações e posicionamentos, de modo a invocar perspetivas de atuação sobre os silos, que se adequem a cada situação específica, a cada contexto e a cada lugar. É no confronto entre as abordagens enunciadas, que se evidencia, mais do que a pertinência, a emergência social e cultural de uma ação diligente, quer ao nível particular de cada peça silar, quer do sistema, do qual era parte integrante a linha de caminho de ferro, que através do seu traçado permitia interligar todas as peças silares e garantir o seu funcionamento a escala industrial; ABSTRACT: This research presents a systematic study of architectural expression of wheat crop agro-industrial development, in particular the "Wheat Campaign", started in 1929 and continue during the "New State", until 1969. We first proceed to map the built elements related to production processes, silage and wheat industrial grinding, as well as the ways of transportation, establishing a comparative analysis with other countries and regions, in order to reveal the impact of these objects in various territories and landscapes. We seek to understand the relationships between the architectural form of the silo (whose design is mainly a result of an intrinsically programmatic response linked to its primary function - cereal storage) and the places where they are implemented and the landscapes which they sought to communicate and articulate. Secondly, we describe the current status of each copy of the "wheat architectures" in Alentejo, with the main objective of attain, at first, the understanding of each particular case and, then, to establish a connection between the different contexts in which they operate and their formal characteristics, in order to conceive and discuss their future use, equating different perspectives of action in the buildings. Finally seeks to introduce a discussion according to different orientations and positions in order to invoke prospects for action on the grain elevators that are appropriate to each specific situation, every context and every place. It is the clash between the stated approaches, which shows more than the relevance, it shows social and cultural emergence of a diligent action on the particular level of each grain elevator on the system, which was an integral part of the railway, which through its tracing allowed to interconnect all grain elevators and assure its operation on an industrial scale

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Mendonça, Gustavo Maia Queiroz de. "Descritor local baseado no algoritmo SIFT para rastreamento e segmentação de objetos em vídeos via grafos de regiões". reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/21250.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016.
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Na segmentação de objetos em vídeos por intermédio de um rastreamento quadro a quadro de regiões, a manutenção da coerência temporal depende diretamente da qualidade desse rastreamento ao longo dos quadros. Para esse fim, adaptou-se para o domínio dos superpixels processados como grafos de regiões, princípios de um extrator de características bastante difundido, o SIFT, que exibe grande eficiência na identificação/rastreamento de objetos em cenas. Um descritor é criado para cada região, a partir de histogramas de orientação do gradiente de setores ao redor do vértice, calculado de forma a garantir, como no SIFT, invariância à escala, rotação e iluminação. As contribuições do descritor proposto na segmentação de objetos em vídeo, feita a partir de corte em grafos, são testadas em três níveis: ajuste, ou compensação, de movimento do objeto em cena; reforço nos pesos de ligação entre arestas dos grafos, para os elementos considerados correspondentes entre os quadros e; determinação de grafos equivalentes com redução no número elementos guiada pela correspondência encontradas a partir algoritmo proposto. ________________________________________________________________________________________________ ABSTRACT
In the segmentation of object in video through frame to frame region tracking, the temporal coherence maintenance depends directly on the quality of the regions tracking along the frames. To this aim, principles of a widespread feature extractor, the SIFT, were adapted for the superpixels domain rendered as region graphs, which exhibits high efficiency in identification/tracking of objects in scenes. A descriptor is created to each vertex of graph, from orientation histograms of the gradient of bins around the vertex, calculated to ensure, as the SIFT, a scale, rotation and lighting invariance. The contributions of the proposed descriptor in the segmentation of objects in video, performed by a graph cut, are tested on three levels: the adjustment or compensation of the movement of object in scenes; the strengthening of the connection weights between edges of the graphs for the elements considered matches between frames and; the determination of equivalent graphs with reduction in the number elements guided by matches found through the proposed algorithm.

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Libri sul tema "Grains de silt"

Franck, Irene M. Silk. Danbury, CT: Grolier, 2003.

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El diploma del rey Silo. La Coruña: Fundación Pedro Barrié de la Maza, 2007.

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Hoogervorst, José. Sorghum milling business manual =: Bukana ya kgwebo ya go sila mabele. Gaborone, Botswana: BOMOA, 1992.

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Kelleher, Stephen F. D. Enquête en vertu de l'article 248 du Code canadien du travail (Partie III--Normes du travail)--Règlement de 1979 sur la durée du travail des agents et directeurs d'élevateurs régionaux, dans sa forme modifiée: Recommandations et rapport. Ottawa, Ont: Développement des ressources Canada, 1998.

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England and Wales. Sovereign (1625-1649 : Charles I). By the King: Whereas there hath fallen out an interruption of amitie betweene the Kings Maiestie and the most Christian king .. Imprinted at London: By Bonham Norton and Iohn Bill ..., 1985.

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Sepowski, Stephen J., a cura di. The Ultimate Hint Book. Old Saybrook, CT: The Ultimate Game Club Ltd., 1991.

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Primedia. Grain Elevator and Silo Emergencies. Delmar Thomson Learning, 1998.

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Wilson, David Niall. To Sift Through Bitter Ashes (The Grails Covenant , No 1). White Wolf Games Studio, 1997.

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The 2006-2011 World Outlook for Farm Forage, Grain, and Sealed Storage Silo and Grain Bin Unloaders. Icon Group International, Inc., 2005.

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Parker, Philip M. The 2007-2012 World Outlook for Farm Forage, Grain, and Sealed Storage Silo and Grain Bin Unloaders. ICON Group International, Inc., 2006.

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Capitoli di libri sul tema "Grains de silt"

Al-Dousari, Noor, Modi Ahmed, Ali Al-Dousari, Musaad Al-Daihani e Murahib Al-Elaj. "Dust Particle Size and Statistical Parameters". In Atlas of Fallen Dust in Kuwait, 57–93. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66977-5_3.

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AbstractGrain ‘size’ can be specified and measured in several different ways. All methods of grain size determination have blemishes, and the choice of the most appropriate method is governed by the nature of the sample and the use to which the data are placed. Four main methods are currently used for size analysis of sands: (a) sieving; (b) settling tube analysis; (c) electro-optical methods, including Coulter Counter analysis and laser granulometry; and (d) computerized image analysis. The classification of the particle size distribution of Kuwait dust was mapped according to the parameters proposed by Folk And Ward (1957) which were widely used for quantitative comparisons between natural grain size distribution and the lognormal distribution that shows better sorted sediments have lower values of σ1. Maps of the distribution of dust in Kuwait were obtained that included: fine sand (F.S.), Coarse sand (C.S), Medium Sand (M.S), Very Fine Sane (V.F.S), Very Coarse Silt (V.C.Silt), Coarse Silt (C.Silt), Medium Silt (M.Silt), Fine Silt (F.Silt), Very Fine Silt (V.F.Silt), in addition to that, the deposition percentage of Clay, Sand, mud (silt plus clay) and silt were provided.

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Horabik, Józef, e Marek Molenda. "Properties of Grain for Silo Strength Calculation". In Physical Methods in Agriculture, 195–217. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0085-8_12.

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Aytemiz, Derya, e Tetsuo Asakura. "Application of Bombyx mori Silk Fibroin as a Biomaterial for Vascular Grafts". In Biotechnology of Silk, 69–85. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7119-2_4.

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Ali, Jauhar, Mahender Anumalla, Varunseelan Murugaiyan e Zhikang Li. "Green Super Rice (GSR) Traits: Breeding and Genetics for Multiple Biotic and Abiotic Stress Tolerance in Rice". In Rice Improvement, 59–97. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66530-2_3.

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AbstractThe frequent fluctuations in global climate variability (GCV), decreases in farmland and irrigation water, soil degradation and erosion, and increasing fertilizer costs are the significant factors in declining rice productivity, mainly in Asia and Africa. Under GCV scenarios, it is a challenging task to meet the rice food demand of the growing population. Identifying green traits (tolerance of biotic and abiotic stresses, nutrient-use efficiency, and nutritional grain quality) and stacking them in high-yielding elite genetic backgrounds is one promising approach to increase rice productivity. To this end, the Green Super Rice (GSR) breeding strategy helps to pool multi-stress-tolerance traits by stringent selection processes and to develop superior GSR cultivars within a short span of 4–5 years. In the crossing and selection process of GSR breeding, selective introgression lines (SILs) derived from sets of early backcross BC1F2 bulk populations through both target traits and non-target traits were selected. Genotyping of SILs with high-density SNP markers leads to the identification of a large number of SNP markers linked with the target green traits. The identified SILs with superior trait combinations were used for designed QTL pyramiding to combine different target green traits. The GSR breeding strategy also focused on nutrient- and water-use efficiency besides environment-friendly green features primarily to increase grain yield and income returns for resource-poor farmers. In this chapter, we have highlighted the GSR breeding strategy and QTL introgression of green traits in rice. This breeding strategy has successfully dissected many complex traits and also released several multi-stress-tolerant varieties with high grain yield and productivity in the target regions of Asia and Africa.

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Hancock, James F. "The eastern Roman Empire and the rise of Venice." In Spices, scents and silk: catalysts of world trade, 157–71. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249743.0013.

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Abstract Providing a situation of the eastern Roman Empire after Emperor Justinian died, the chapters also gives summary of the economic growth of various European countries in the middle ages. There were many other maritime republics that arose in Italy during the Middle Ages other than Venice. These included Genoa, Pisa, Ragusa (now Dubrovnik), Gaeta, Ancona and Noli. The most powerful were Genoa, Pisa and Amalfi, who carried on extensive trade across the Mediterranean and built strong navies for protection and conquest. Venice came to dominate Adriatic trade, while Pisa and Genoa focused their trade more heavily on Western Europe. Aside from these, it was also high time for the western maritime trade since the Black Sea area was particularly important to Constantinople as a source of grain, fish and salt, and to a much lesser extent spices and silks. Its importance as a source of spices and silk had been greatly diminished over the last century due to the unrest in Central Asia leading to the breakup of the Silk Routes and the shift in the spice trade from the Persian Gulf to the Red Sea resulting from the political instability of the Abbasid Caliphate. The chapters also gave a summary how the economic relations between Venice and the Byzantine Empire led to war and the sacking of Constantinople.

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Hohlrieder, M., K. Cicha, A. Teuschl, M. van Griensven, H. Redl e J. Stampfl. "Bioreactor and scaffold design for the mechanical stimulation of silk based anterior cruciate ligament grafts". In IFMBE Proceedings, 208–10. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03900-3_60.

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Gupta, Prerak, e Biman B. Mandal. "Fabrication of Small-Diameter Tubular Grafts for Vascular Applications Using Mulberry and Non-mulberry Silk Proteins". In Methods in Molecular Biology, 125–39. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1708-3_11.

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Keefer, Robert F. "Nature of Soil Erodibility". In Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0008.

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Inherent properties of a soil determine the extent to which that soil will erode. These properties are soil texture, soil structure, soil permeability, and the amount of soil organic matter. Soil texture consists of a mixture of soil particle sizes of sand, silt, and clay. Soil texture is also related to water movement into the soil [infiltration] and water movement through a soil (permeability). Sand grains are large and difficult to move; however, they are easily detached. Clay particles often stick together and therefore are difficult to detach; however, once detached the clays remain suspended and are easily carried and separated from the original soil mass by water. Silt is intermediate in size between sand and clay, but silt is both easily detached and easily transported. Thus, any soil that has large amounts of silt will erode easily. Infiltration. Water moves into and within a soil through the large macropores and only a very limited amount in the small micropores. Sandy soils have many large pores allowing water to move into the soils by infiltration. Conversely, clay soils have many microspores through which water passes only very slowly. Therefore, during a moderate storm, runoff and erosion would be greater from a soil with more fine textured clays than from a soil where coarse texture dominates. Permeability. Once water enters a soil, it flows within the soil. The extent of internal movement of water in a soil is the permeability of that soil. A soil aggregate is a soil granule or soil crumb consisting of a number of soil grains, that is, silt or clay, held together by a cementing substance. Aggregation is the condition of a soil having many individual aggregates. Soils that have many large stable aggregate are more permeable and are difficult to detach and erode. An aggregate has stability when it is not broken easily by water. Soil aggregates help keep the soil receptive to rapid infiltration of water and keep water from moving over the soil and eroding it.

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"silt grain". In Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 1233. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_193656.

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"“There Is Only a Certain Amount of Grain Produced”: Granaries and the Role of the State in the Food Supply System". In Tigers, Rice, Silk, and Silt, 226–48. Cambridge University Press, 1998. http://dx.doi.org/10.1017/cbo9780511511998.010.

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Atti di convegni sul tema "Grains de silt"

Velbel, Michael. "MINERALOGY OF SAND- AND SILT-SIZE GRAINS ON MARS FROM PHOENIX OM IMAGES". In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-367863.

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Johnson, Kendall, Latisha Ashley Brengman e Elizabeth J. Trower. "GRAIN SIZE DISTRIBUTIONS AND MINERALOGY OF COATED GRAINS, DETRITAL SAND AND SILT WITHIN THE ∼1.9 GA MESABI IRON RANGE, MINNESOTA". In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-321622.

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Isaifan, Dina Jamal, e Yousra Suleiman. "Quantifying Biomass of Microphytobenthos in sediments of Mangroves in the east coast of Qatar". In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0061.

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Mangroves, Avicennia marina, are highly productive coastal ecosystems with capacity to store carbon within plants and in sediments. Micropytobenthos (MPB) in the sediments also fix carbon and play a significant role in carbon burial. However, there is paucity of information on the role of MPB in coastal carbon budget. We quantified the biomass of MPB as an important carbon pool in the mangrove of Al Thakhira, located at the east coast of Qatar. Sediments at different tidal levels namely, supratidal, intertidal, and subtidal were collected and analyzed for grain size, chlorophyll (a), total carbon, and inorganic carbon contents. Results indicated that sand was the dominant species (60%), followed by silt (39%) and clay (1%) at all tidal levels. While the supratidal level had significantly higher silty sand content, silt dominated the intertidal levels. Moreover, chlorophyll (a) was significantly influenced by tidal levels with highest levels in the subtidal level sediments, where mangroves grow extensively. Results also demonstrated that as we move towards the intertidal zone, the total carbon content in sediments gets higher. Finally, chlorophyll (a) and TOC% were positively associated (r=0.643) in all tidal zones. As we move towards the mangrove subtidal growth area, the total carbon content in sediments gets higher. This work recommends that mangrove forests in Qatar be protected by special sanctuaries and law-enforcement to maintain this natural and dynamic blue carbon ecosystem.

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Brandes, Horst G. "Permeability of Marine Sediments and Tropical Volcanic Soils". In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83543.

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Permeability values for a range of fine-grained deep-sea sediments are presented and evaluated in terms of index properties such as plasticity, grain size and carbonate content. It is found that whereas clay-rich sediments have similar permeabilities to those of equivalent land-based fine-grained soils, the presence of volcanic, carbonate and other non-clay fractions tends to increase permeability somewhat. Volcanic silty-clayey soils from Hawaii have comparable permeability values, although they can be slightly more permeable.

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Denis, Jean-Marc, e Jean-Louis Ripoll. "Gas phase synthesis of hetero-sila-alkenes of cosmochemical importance". In The 50th international meeting of physical chemistry: Molecules and grains in space. AIP, 1994. http://dx.doi.org/10.1063/1.46606.

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Martin, A., F. Dubois, Y. Monerie, F. Radjai, Masami Nakagawa e Stefan Luding. "Jamming and flow statistics in a silo geometry". In POWDERS AND GRAINS 2009: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON MICROMECHANICS OF GRANULAR MEDIA. AIP, 2009. http://dx.doi.org/10.1063/1.3180011.

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Jäckel, Stefan, Ralf Schünemann, Thomas Mütze e Urs A. Peuker. "Prediction of silo-vibrations using a modified lambdameter". In POWDERS AND GRAINS 2013: Proceedings of the 7th International Conference on Micromechanics of Granular Media. AIP, 2013. http://dx.doi.org/10.1063/1.4812022.

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Samadani, Azadeh, Daniel L. Blair e A. Kudrolli. "Clustering, Jamming and Segregation in Cohesive Granular Materials". In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32478.

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We present a series of experiments to investigate the stability, flow and segregation when liquid bridges or magnetic attraction forces between grains are present. Quantitative data is obtained by high speed and high resolution imaging. First, we measure the angle of repose of a granular pile formed by pouring wet grains in to a quasi-two dimensional silo and compare them to existing models. Second, we measure the size separation of bi-disperse grains as a function of size ratio and viscosity of the liquid. Finally, we introduce a vibro-fluidized system of magnetized particles to study the effect of cohesive forces and inelastic collisions on the formation of clusters and velocity distributions.

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Hsiau, Shu-San, Chin-Chi Hsu, Jiri Smid, Masami Nakagawa e Stefan Luding. "The Discharge of Fine Silica Sands in a Silo". In POWDERS AND GRAINS 2009: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON MICROMECHANICS OF GRANULAR MEDIA. AIP, 2009. http://dx.doi.org/10.1063/1.3180008.

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Francingues, Norman, Douglas Thompson, E. Clark McNair e Luis Saenz. "The Silt Wing Excavator - An Innovative Sediment Leveling and Grading Device". In Third Specialty Conference on Dredging and Dredged Material Disposal. Reston, VA: American Society of Civil Engineers, 2003. http://dx.doi.org/10.1061/40680(2003)6.

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Rapporti di organizzazioni sul tema "Grains de silt"

Strohbehn, Daryl R., Daniel D. Loy, Daniel G. Morrical, H. Joe Sellers e Dennis R. Maxwell. Modified Distillers’ Grain with Solubles Stored for an Extended Period in a Silo Bag Used to Develop Breeding Heifers. Ames (Iowa): Iowa State University, gennaio 2008. http://dx.doi.org/10.31274/ans_air-180814-585.

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Strohbehn, Daryl R., Daniel D. Loy, Daniel G. Morrical, Joe Sellers e Dennis R. Maxwell. Modified Distillers Grain with Solubles Stored for an Extended Period in a Silo Bag used to Develop Breeding Heifers. Ames: Iowa State University, Digital Repository, 2008. http://dx.doi.org/10.31274/farmprogressreports-180814-147.

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Zarillo, Gary, Sara Ramos, Kristopher Effinger, Kristen Becker, Irene Watts, Katherine Brutsché, Brian McFall e Douglas Krafft. Evaluating cross-shore sediment grain size distribution, sediment transport, and morphological evolution of a nearshore berm at Fort Myers Beach, Florida. Engineer Research and Development Center (U.S.), marzo 2022. http://dx.doi.org/10.21079/11681/43780.

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Navigation channels are periodically dredged to maintain safe depths. Dredged sediment was historically placed in upland management areas or in offshore disposal areas. Florida state law prohibits placement of beach fill sediment that contains more than 10% by weight of silt and clay, which is typically a characteristic of dredged material. An alternative is placement in a nearshore berm. Some potential benefits of nearshore berms include wave energy dissipation, reduced cost of dredging and shore protection, and possible onshore movement of the berm material. This study considers sediment distribution, morphological evolution, sediment transport, and shoreline trends along Fort Myers Beach, Florida, related to the nearshore berm constructed in August 2016. Due to timing of the field study, this report also includes information on the influence of a major hurricane that impacted the area. The overall conclusion of this study is that the dredge-sourced sediment in the berm performed as expected. Within 2 years, the berm adjusted to the shoreface environment, maintained a large part of its original volume, and contributed to protection of the beach and shoreline. The impact of Hurricane Irma included a shift in sediment textures and a large but temporary increase in shoreface sediment volumes.

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David, Uttal, Katherine James, Steven McGee e Phillip Boda. Laying the Foundation for a Spatial Reasoning Researcher-Practitioner Partnership with CPS, SILC, and The Learning Partnership. Northwestern University, settembre 2021. http://dx.doi.org/10.51420/report.2020.1.

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The goal of this project was to explore how explicit instruction in spatial reasoning in primary grades can contribute to reductions in variation in STEM outcomes for low-income, minority students in the Chicago Public Schools (CPS). Our project focused on the persistent gender, racial and ethnic, and socioeconomic inequalities in STEM educational and career achievement and attainment. Our approach to addressing this problem was guided by research evidence that much of the variation in STEM outcomes for these groups can be explained by spatial reasoning abilities. Importantly, spatial reasoning skills can be improved through practice, but are rarely explicitly taught in the classroom. The spatial reasoning needs and opportunities identified by this work are relevant to CPS in that they focus on the prevalent science, math, and computer science curricula currently used in CPS K-2 instruction. As such, our findings provide specific, actionable guidance for the development of curricular supports that infuse explicit spatial reasoning instruction.

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Using Farmstead Equipment (silo unloader, bunk feeder, grain auger, conveyor). Marshfield Clinic Research Foundation, 2018. http://dx.doi.org/10.21636/nfmc.nccrahs.youthwork.farmstead.g.2018.

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Farm worker asphyxiated in grain silo in Indiana, November 1, 1986. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, maggio 1987. http://dx.doi.org/10.26616/nioshface8739.

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Grain elevator leadman suffocates after being engulfed in shelled corn inside silo, April 5, 1989. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, agosto 1989. http://dx.doi.org/10.26616/nioshface8933.

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Paleomagnetic and 40Ar/39Ar results from the Grant intrusive breccia and coparison to the Permian Downeys Bluff Sill; evidence for Permian igneous activity at Hicks Dome, southern Illinois Basin. US Geological Survey, 1997. http://dx.doi.org/10.3133/b2094g.

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