Dissertations / Theses: 'Granule properties'

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Heinze, Karsta. "From grain to granule : the biomechanics of wheat grain fractionation with a focus on the role of starch granules." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS072/document.

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La culture du blé est l’une des plus importantes au monde. Le grain de blé est un matériau composite naturel dont la majeure partie est constituée d’albumen amylacé formé d’un assemblage compact de granules d’amidons (glucides) enchâssés dans une matrice protéique (gluten). Pour obtenir des produits comme la farine, la structure de l'albumen doit être fragmentée en broyant les grains sous des fortes contraintes. La quantité et la qualité des produits obtenus dépendent du comportement de l’albumen à la fragmentation. En raison de sa nature composite, le comportement rhéologique du grain est tributaires des propriétés mécaniques des phases qui le composent (granules, gluten, pores), de leurs interactions, ainsi que de leur distribution spatiale. Les granules d’amidons sont de formes relativement sphériques et de tailles micrométriques, tandis que les protéines sont organisées en un réseau entourant les granules. L'interaction entre l'amidon et ce réseau protéique est influencée par certaines protéines, les puroindolines, dont la présence et le type d’allèle sont contrôlées génétiquement. Si les gènes codant pour les puroindolines sont présents sous forme sauvages, la dureté meunière, c’est à dire l’aptitude à la fragmentation du grain est faible. L’origine de ce comportement est liée à une adhérence limitée entre matrice protéique et amidon. L'absence totale de puroindolines chez le blé dur conduit au contraire à une dureté très élevée des grains et à une forte adhérence. L'objectif de cette thèse est d'étudier, à partir d’une approche multidisciplinaire, la biomécanique du fractionnement du grain de blé en mettant l'accent sur le rôle des granules d'amidon. Des échelles de taille différentes sont considérées : échelle micrométrique du granule et de la matrice protéique; agencement complexe de ces composants dans l'albumen et échelle millimétrique du grain. Ainsi, des expériences de broyage à l'échelle du grain ont été combinées avec des mesures nano-mécaniques par microscopie à force atomique (AFM) et des simulations numériques.Le comportement au broyage a été étudié en utilisant un micro-moulin instrumenté. Une comparaison a été effectuée entre des essais réalisés sur une variété de blé dur et sur la même variété dans laquelle ont été introduits les gènes codant pour les puroindolines. Un changement significatif du comportement mécanique des grains transformés, attribuable uniquement à la présence de puroindolines, a été observé - en termes d'énergie consommée, - de productivité en farine et - de taux d'amidon endommagé. Ces changements sont compatibles avec l'hypothèse d'une faible adhérence, entre granules d'amidon et matrice protéique, induite par la présence des puroindolines et montrent l'effet significatif de celles-ci sur le comportement à la fragmentation. Ces modifications de comportement mécanique peuvent être étudiées par des mesures AFM nano-mécaniques. Pour compléter des travaux antérieurs ayant permis la mesure des propriétés de l'amidon et du gluten, une méthode basée sur des mesures AFM en mode résonance de contact (CR-AFM) a été développée. Celle-ci permet de cartographier les propriétés directement à l'intérieur des granules d’amidon et prend en compte à travers un modèle théorique les variations importantes de topographie observées dans les sections de grains. Ces études CR-AFM de l'albumen ont ensuite porté sur les propriétés mécaniques des granules d'amidon d'origines botaniques différentes (céréales et légumineuses).Enfin, le rôle de la distribution bimodale en taille des granules d'amidon sur la fragmentation de l'albumen a été précisé à partir d’une étude numérique paramétrique détaillée. Les propriétés mécaniques élastiques et à la rupture ont été analysées en détail, ainsi que le rôle dominant de la ténacité des granules et de l'adhérence à l'interface sur l’endommagement de l’amidon
The wheat grain is a natural composite material of worldwide importance. The major part of the grain is the starchy endosperm. To obtain food products, such as flour, the endosperm’s compact structure needs to be disintegrated, which is achieved by milling the grains under high forces. The quantity and quality of the milling products notably depend on the fragmentation behaviour of the endosperm.Due to the endosperm’s composite nature, this behaviour depends strongly on the mechanical properties of its components and their interaction. The main components of the endosperm are carbohydrates and proteins. The carbohydrates are deposited as starch in the form of granules of micro-meter size, whereas proteins form a network (gluten), which surrounds the starch granules. The interactions between starch and proteins is believed to be influenced by certain non-gluten proteins (puroindolines), whose presence and allelic state are genetically controlled. If puroindoline genes are present in the wild-type form, grain hardness is low, which have been related to low starch-protein adhesion. The complete absence of puroindolines in the durum wheat species leads to very high grain hardness and indicates a strong adhesion.The aim of this thesis was to investigate the biomechanics of wheat grain fractionation with a focus on the role of the starch granules therein, which was pursued with a multi-disciplinary approach. Different size scales were considered, from the micro meter-sized structures of starch and protein, the complexity of their arrangement in the endosperm, up to the millimeter-sized grains. In this work, grain-scale milling experiments were combined with nano-mechanical measurements by atomic force microscopy (AFM) and numerical simulations.The milling behaviour of a transgenic durum wheat line, which contained puroindoline genes, was determined by grain scale milling experiments and compared to the milling behavior of non-modified durum wheat. A significant change of milling behavior of the transformed durum wheat grains was observed in terms of milling energy, flour yield and starch damage, which was solely attributable to the presence of puroindolines. The observed changes were consistent with the hypothesis of a lower adhesion between starch granules and protein matrix due to the presence of puroindolines and confirmed the significant effect of puroindolines on the fragmentation behaviour, independent of the grain’s genetic background.The change of fragmentation behaviour is a result of modifications of the mechanical properties of the endosperm’s components and/ or their interaction. Such modifications can be investigated by AFM nano-mechanical measurements. Based on previous work illuminating the global nano-mechanical properties of starch and gluten, contact-resonance AFM (CR-AFM) was applied to obtain maps of the nano-mechanical properties inside the grains. Due to the high topography variations of grain section surfaces and the non-trivial correlation between surface slope and contact resonance-frequency, which hindered a straight-forward interpretation of CR-AFM measurements, a practical method based on existing analytical models of the cantilever vibration was developed to correct the measurements. CR-AFM studies of the endosperm were then focused specifically on the mechanical properties of starch granules and the link to starch structure, and applied to the study of starches from wheat in comparison to plants from different botanical origin (other cereals and legumes).Finally, the role of starch granules, their size distribution, and mechanical properties on endosperm fragmentation was analysed by parametric numerical studies. The influence of the bi-modal size distribution of granules on the mesoscale mechanical properties was shown, as well as the governing role of granule toughness and interface adhesion on the granule damage

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Sims, Robert. "On the transmission properties of synapses made between granule cells and cerebellar Purkinje cells." Thesis, Aston University, 2003. http://publications.aston.ac.uk/11071/.

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In the cerebellar cortex, forms of both long-term depression (LTD) and long-term potentiation (LTP) can be observed at parallel fibre (PF) - Purkinje cell (PC) synapses. A presynaptic variant of cerebellar LTP can be evoked in PCs by raised frequency stimulation (RFS) of parallel fibre at 4-16Hz for 15s. This form of LTP is dependent on protein kinase A (PKA) and nitric oxide (NO), and can spread to distant synapses. Application of an extracellular NO scavenger, cPTIO, was found to prevent the spread of LTP to distant PF synapses in rat cerebellar slices. G-substrate may be an important mediator of the NO-dependent pathway for LTD. 8-16Hz RFS of PFs without a high concentration of calcium chelator in the postsynaptic cell evokes LTD. In cerebellar slices from wild-type and transgenic, G-substrate knockout mice, 8Hz RFS was applied to PFs, with a low concentration of postsynaptic calcium chelator. In PCs from wild-type mice, LTD predominated, whereas in those from transgenic mice LTP predominated. The ascending axon (AA) segment of the granule cell axon forms synapses with PCs as well as the PF segment. PPF and fluctuation analysis of EPSCs in rat PCs confirmed that the release sites of AA synapses have a greater probability of transmitter release than PF synapses. Furthermore, AA release sites have greater mean quantal amplitude than PF synapses, which is not due to a different type of postsynaptic receptor. AA synapses were found to have limited capacity to undergo the presynaptic variant of LTP, and were potentiated less than PF synapses in the presence of the PKA activator, forskolin. AA synapses also did not undergo the postsynaptic form of LTP, nor LTD induced by conjunctive stimulation of climbing fibre and PF.

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Chan, Yuen Cheung. "Quality evaluation and anti-chronic glomerulonephritis properties of a patent herbal drug yi-shen-hua-shi granule." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/825.

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Yi-Shen-Hua-Shi (YSHS) granule is a Chinese patent drug for treating chronic glomerulonephritis (CGN). It was marketed in 2009. However, up to now, there is no report about the quality and pharmacological activities of this product. In this work，we evaluated the quality and anti-CGN effects of the drug. To evaluate the quality of the granule, a qualitative and quantitative HPLC-DAD analytical method was developed. For qualitative analysis, HPLC fingerprint of ten batches of YSHS granule was established. The fingerprints were analyzed using similarity evaluation, hierarchical cluster analysis (HCA), principal components analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) based on 15 characteristic fingerprint peaks. Similarity values of 10-batche samples were all above 0.960, indicating a stable quality. Minor differences were observed among batches by HCA and PCA. For quantification analysis, contents of six constituents in the granule were simultaneously measured. To establish the chemical profile of the granule, a HPLC-Q-TOF- MS/MS method was developed. A total of 105 peaks were detected using HPLC-Q-TOF-MS/MS in the granule, of which, 99 were tentatively identified as terpenoids, flavonoids, coumarins, alkaloids, phenols and other types of compounds, and 15 were further validated with reference substances. HPLC fingerprint chromatogram establishment, quantification analysis of 6 constituents and compound identification should improve the quality control of YSHS granule. To study the pharmacological activities of the granule, we investigated its anti-CGN effects and TGFβ signaling-related mechanism of action. A CGN rat model was established by injection of cationization-bovine serum albumin (C-BSA) for five weeks. After C-BSA injection, drugs were intragastrically administered to the rats once daily for four weeks. Clinical signs were recorded daily. Urine and serum biochemical parameters were analyzed using respective kits. Protein levels were examined by Western blotting. Pathological changes of renal tissues were evaluated using HE and Masson's trichrome staining. No significant differences in body weights and clinical signs were found among normal, model and drug treatment groups. Proteinuria; albuminuria; increased urine volume; elevated creatinine, urea nitrogen, triglyceride levels and total cholesterol in serum; decreased serum total protein and albumin; as well as renal pathological damages and fibrosis were observed in CGN model rats. YSHS granule ameliorated all the abnormal behavioral and biochemical changes in the model rats. Mechanistic investigations revealed that YSHS granule down-regulated proteins levels of TGFβ1, phospho-Smad2/3 (Thr 8) and Smad4 in rat renal tissues. These findings indicate that the drug has anti-CGN effects in rats, and inhibiting TGFβ signaling contributes to the underlying mechanisms. In summary, our chemical analytical studies will help in improving the quality control of YSHS granule. Our bioactivity and mechanistic studies provide a pharmacological basis for the clinical use of the granule in treating CGN.

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Liu, Jing. "EFFECT OF AMYLOSE AND PROTEIN OXIDATION ON THE THERMAL, RHEOLOGICAL, STRUCTURAL, AND DIGESTIVE PROPERTIES OF WAXY AND COMMON RICE FLOURS AND STARCHES." UKnowledge, 2013. http://uknowledge.uky.edu/animalsci_etds/23.

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The effects of oxidation by sodium hypochlorite (0, 0.8, 2, and 5%, NaOCl), the presence of endogenous proteins, and amylose content on waxy and common rice flours (WF, CF) and starches (WS, CS) were investigated in terms of in vitro starch digestibility, morphology and surface properties, and thermal and rheological characteristics. The concentration of NaOCl had an effect on all the samples including WF, CF, WS, and CS. The carbonyl and carboxyl group contents increased up to 25 and 10 folds (P < 0.05) of oxidized starches (WS, CS), respectively. Only mild oxidation (P < 0.05) occurred in flours (WF, WS). In addition, endogenous proteins were oxidized according to amino acid analysis and SDS–PAGE results. Glu+Gln, Gly, His, Arg, Tyr, and Lys were more sensitive to NaOCl oxidation. Disulfide bonds, hydrophobic force, and hydrogen bonds were involved in protein polymerization after NaOCl oxidative modification. In granular state, the in vitro starch digestibility of WF, WS, and CS decreased by 5% NaOCl oxidation. After gelatinization, only 2 and 5% oxidized WS had lower digestibility. Scanning electron microscopy and confocal laser scanning microscopy further demonstrated that protein existed on the surface of starch granules and had aggregation by oxidation. X-ray diffraction patterns showed the crystallinity of 5% oxidized flours and starches was reduced compared with all their non-oxidized samples. Thermal and rheological properties were analyzed by differential scanning calorimetry and rheometer, respectively. Starch gelatinization peak temperature of flours (WF, RF) was increased by 3 °C, but starches (WS, CS) had a significantly decrease by 8 °C. Viscoelastic patterns were dramatically changed by oxidation. Oxidized WF and CF had increased in both viscosity and elasticity by oxidation, whereas both WS and CS had significantly lower viscoelasticity after oxidative modification.

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Jayakody, J. A. Luckshman Priyadharshana. "The effect of acid hydrolysis on granular morphology and physicochemical properties of native cereal starch granules." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62392.pdf.

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Paine, A. C. "Elastic properties of granular materials." Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245957.

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Stewart, James Alexander. "Engineering the properties of spray-dried detergent granules." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548673.

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Griffith, J. D. "The drying and absorption properties of surfactant granules." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599715.

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The work in this thesis contributes to an understanding of the evolution of the drying kinetics and internal microstructure of a model detergent paste (called a crutcher mix) during the spray drying stage in the manufacture of washing powders in order that the physical and cleaning properties of the final dried detergent powder can ultimately be more easily controlled and manipulated. Regularisation algorithms were developed and employed in conjunction with nuclear magnetic resonance (NMR) spectroscopy and relaxometry techniques to characterise both the bulk and individual constituent components of crutcher mix. In addition, novel 2-D relaxation methods were applied and used to characterise the sizes of the different phase domains within crutcher mix. The in-situ drying of crutcher mix has been investigated using NMR. Large samples have been studied to identify the changes in bulk properties, whilst studies on individual 10 µl droplets mimic the material geometry in an industrial spray dryer. Quantitative imaging and relaxometry experiments have been used to show that the drying is in the failing rate regime throughout and to deduce that there is preferential drying of the water-rich phase over the surfactant-rich phase. Novel rapid pulsed field gradient (PFG) experiments have been destroyed and then used to probe the dynamic evolution of the internal microstructure during drying. A parameter free model describing the drying of single detergent pate droplets has been established and compared favourably to experimental data. The model has been expanded to provide very preliminary simulations of the drying conditions within industrial spray dryers. A feasibility study looking into the use of NMR to study the absorption properties of the dried granular detergent product was also conducted. The ingress of water into a compacted detergent tablet has been monitored through the acquisition of 1-D image profiles of the water content and shown to exhibit Case II diffusion characteristics.

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Uthus, Lillian. "Deformation Properties of Unbound Granular Aggregates." Doctoral thesis, Norwegian University of Science and Technology, Department of Civil and Transport Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1628.

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This thesis discusses the resilient and permanent deformation properties of unbound granular aggregates for use in road structures. One of the objectives of the thesis is to identify the influence of the physical properties of the aggregate grains, such as grain size, grain shape, surface texture, mineralogy and mechanical strength through cyclic load triaxial testing. A second objective is to study the effect of water on the deformation properties of materials as well as their frost susceptibility. The third objective is to study the effect of micromechanical properties using a discrete element model (DEM).

Deformation in unbound granular materials under cyclic loading is divided into a resilient (recoverable) part and a plastic part that does not recover. The elastic strain represents the denominator in the resilient modulus and the non-recoverable strain results in permanent deformations over time. As the resilient response is non-linear, the resilient deformations may be interpreted using several models for curve fitting. Two of the simplest models are the k-θ model and Uzans model. The interpretation of the permanent deformation behaviour of unbound aggregates is complicated, as there is a need for a failure criterion to define when the material is at a failure stage. Two methods used for interpretation of the permanent deformations are mentioned in Chapter 3 of this thesis; the Shakedown approach and the “Coulomb approach”.

Many factors are known to affect the deformation properties in unbound materials. In this thesis the effect of most of these factors is investigated in the six papers. In Chapter 4 the influence of the different factors is discussed on the basis of the results from the papers and findings in the literature. Cyclic load triaxial testing has been the main method to test the deformation properties of the selected unbound materials. This is so far one of the best methods for laboratory simulation of traffic loading.

Discrete element modelling is performed to gain a better understanding of the deformation properties of unbound aggregates tested in a triaxial apparatus under cyclic loading. This method provides useful information about the contact mechanics between neighbouring particles and the interaction of the grains. In addition, unbound spherical aggregates have been tested in the laboratory using a triaxial apparatus.

The main factors studied in this thesis are the influence of grain shape, grain size distribution, fines content, mineralogy, dry density and water content. Useful information about these key factors has been obtained. However, there is still work to do in order to utilize the conclusions directly in a pavement design system.

The dry density, degree of saturation and stress level seem to be key parameters for determining the deformation behaviour, but mineralogy, fines content and grain size distribution are also of importance. Regarding the practical consequences, the results show that mineralogy, fines content and grain size distribution must be given more attention in the pavement design manuals. More effort should also be placed on the compaction control phase in situ, in order to avoid initial rutting in the road structure.

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Diaz, BegonÌƒa Ruiz. "Magnetic properties of granular magnetic materials." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428429.

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Oates, Colin John. "Magnetic studies of cobalt based granular thin films." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/12928.

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The magnetic recording media used for hard disks in laptops and PC's is constantly being improved, leading to rapid increases in data rate and storage density. However, by the year 2010, it is predicted that the superparamagnetic limit will be reached, which is potentially insufficient for data storage. At the beginning of this century, CoCr -based alloys are used in longitudinal media since cobalt has a high magnetocrystalline anisotropy. In this thesis, the static and dynamic properties of longitudinal recording thin films were investigated in order to explain and correlate their magnetic characteristics to their recording properties. The samples in question were test samples and some were in commercial use. Magnetic techniques such as high field ferromagnetic resonance and torque magnetometry were used to determine accurately the crystalline anisotropy field. High field ferromagnetic resonance is an ideal tool to determine the crystalline anisotropy, magnetisation, Lande g-factor and the gyromagnetic damping factor. In contrast to previous work, there are no FMR simulations and so all the relevant parameters were determined directly from measurement. Ideally, there should be no exchange interactions between the neighbouring cobalt grains; however, interactions between the grains within the CoCr-alloy recording layer exist. Previous work on the measurements of interactions in recording media involves measuring the sample's magnetisation. In this thesis, an alternative novel method involves torque magnetometry. Another technique that was used in this thesis is small angle neutron scattering, which aims to determine the size of the magnetic grains and compare that with the physical size determined from TEM, by Seagate. There is an extended section on CoxAg1-x granular thin films, which involves determining the sample's g-factor, effective anisotropy, grain size, exchange constant and comparing the FMR lineshapes at 9.5 and 92GHz.

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Zheng, Li-Yang. "Granular monolayers : wave dynamics and topological properties." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1035/document.

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Les cristaux granulaires sont des structures périodiques de particules disposées en réseau cristallin. Les interactions entre ces billes peuvent être modélisées par leurs contacts, qui ont des dimensions et des masses effectives beaucoup plus petites que celles des billes. Ceci induit une propagation d'ondes élastiques dans les structures granulaires avec des vitesses significativement plus lentes que dans le matériau des grains individuels. En outre, en raison de forces de cisaillement non centrales, les rotations de particules peuvent être initiées, conduisant à des modes de phononiques supplémentaires dans ces cristaux. Dans ce manuscrit, on étudie la propagation d’ondes dans les cristaux granulaires monocouche bidimensionnels avec un mouvement des particules hors-plan ou dans le plan. Les propriétés phononiques sont étudiées, y compris les points de Dirac, les modes de fréquence nulle, les modes à vitesse de groupe nulle et leur transformation en modes de propagation lente. En outre, en présence de bords, on peut prévoir également des ondes de bord élastiques à fréquence nulle et extrêmement lentes dans des cristaux granulaires en « nid d'abeille » (graphène granulaire). En outre, les propriétés topologiques des ondes de bord rotationelles-transverses dans un graphène granulaire sont théoriquement démontrées. En induisant une transition topologique, qui transforme l'ordre topologique du graphène granulaire de trivial en non trivial, on peut observer le transport de bord topologique dans le graphène granulaire. Les théories développées pourraient mener potentiellement à des applications sur le contrôle des ondes élastiques par des structures granulaires
Granular crystals are spatially periodic structures of elastic particles arranged in crystal lattices. The interactions between particles take place via their elastic interconnections, which are of much smaller dimensions and weights than the beads. This induces propagation of elastic waves in granular structures at significantly slower velocities than in the individual grains. In addition, due to the existence of non-central shear forces, rotations of particles can be initiated, leading to extra phononic modes in the crystals. In the manuscript, wave dynamics in two-dimensional monolayer granular crystals with either out-of-plane or in-plane particle motion is studied. The phononic properties are investigated, including Dirac points, zero-frequency modes, zero-group-velocity modes and their transformation into slow propagating phononic modes. Furthermore, in the presence of edges/boundaries, zero-frequency and extremely slow elastic edge waves can be also predicted in mechanical granular honeycomb crystals (granular graphene). In addition, topological properties of rotational edge waves in a granular graphene are theoretically demonstrated. By inducing topological transition, which turns the topological order of granular graphene from trivial to nontrivial, topological edge transport in the granular graphene can be observed. The developed theories could promote the potential applications of designed granular structures with novel elastic wave propagation properties

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Dai, Beibing, and 戴北冰. "Micromechanical investigation of the behavior of granular materials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45700680.

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Dawson, Janet Caroline. "The electronic properties of granular and amorphous materials." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318097.

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Bray, David Jonathan. "Statistical properties of a randomly excited granular fluid." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11041/.

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In this thesis we describe numerical simulations performed in one- and two-dimensions of a theoretical granular model called the Random Force Model. The properties of non-equilibrium steady state granular media, which this model is a simple example of, are still hotly debated. We begin by observing that the one-dimensional Random Force Model manifest multi-scaling behaviour brought on by the clustering of particles within the system. For high dissipation we find that the distribution of nearest neighbour distances are approximately renormalisable and devise a geometrical method that accounts for some of the structural features seen in these systems. We next study two-dimensional systems. The structure factor, S(k), is known to vary, for small k, as a power-law with an exponent D_f, referred to as the fractal dimension. We show that the value of the D_f is unchanged with respect to both dissipation and particle density and that the power-law is different from that given in any previous study. These structural features influence the long distance behaviour of individual particles by affecting the distances travelled by particles between consecutive collision. The velocity distribution, P(v), is known to strongly deviate away from Maxwell-Boltzmann statistics and we advocate that the velocity distributions have asymptotic shape which is universal over a range of dissipation and particle densities. This invariance in behaviour of the large-scale structure and velocity properties of the two-dimensional Random Force Model leads us to develop a new self-consistent model based around the motion of single high velocity particles. The background mass of low velocity particles are considered to be arrange as a fractal whereby the high velocity particles move independently in ballistic trajectories between collisions. We use this description to construct the high velocity tail of P(v), which we find to be approximately exponential. Finally we propose a method of structure formation for these systems that builds self-similarity into the system by consecutively fracturing the system into smaller parts.

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Hsiau, Shu-San Hunt Melany L. Hunt Melany L. "Shear-induced transport properties of granular material flows /." Diss., Pasadena, Calif. : California Institute of Technology, 1993. http://resolver.caltech.edu/CaltechETD:etd-08292007-090134.

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Karim, Mohammad. "SURPRISING PROPERTIES OF STATIC AND FLOWING GRANULAR MATTER." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22655.

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The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with increasing filling height due to frictional interactions with side walls. In this paper we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a horizontal conveyor belt. We find that even with high friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle $\theta$ can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system. This work is described in Chapter 2 and has been published in \textit{Physical Review Letters}. We experimentally study quasi-2d dilute granular flow around intruders whose shape, size and relative impact speed are systematically varied. Direct measurement of the flow field reveals that three in-principle independent measurements of the non-uniformity of the flow field are in fact all linearly related: 1) granular temperature, 2) flow field divergence and 3) shear-strain rate. The shock front is defined as the local maxima in each of these measurements. The shape of the shock front is well described by an inverted catenary and is driven by the formation of a dynamic arch during steady flow. We find universality in the functional form of the shock front within the range of experimental values probed. Changing the intruder size, concavity and impact speed only results in a scaling and shifting of the shock front. We independently measure the horizontal lift force on the intruder and find that it can be understood as a result of the interplay between the shock profile and the intruder shape. This work is described in Chapter 3. This dissertation includes previously published and unpublished co-authored material.

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Zhang, Jiajie, and 张家杰. "Laboratory investigation of loosely compacted completely decomposed granite for slope design." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47055601.

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Salahuddin, Mohammed 1959. "Dilatancy effects on the constitutive modeling of granular soils." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276825.

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Unique features of behavior of granular materials make constitutive modeling of these materials a challenge that has not yet been answered completely. Because volume changes are so important for the type of behavior exhibited by frictional materials, it is important to correctly incorporate them in constitutive models, both in terms of their rate of development and their magnitude. In this study a number of consolidated drained triaxial tests are performed to find those features of sand behavior that can be considered "material parameters" and can be used for constitutive modeling of granular soils. Special attention is given to those features of material behavior that are related to dilatancy. A number of published experimental data are also analyzed and useful trends of soil behavior are found.

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Ekblad, Jonas. "Influence of Water on Coarse Granular Road Material Properties." Doctoral thesis, Stockholm : Byggvetenskap, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4329.

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McGuire, Cameron. "Granular flow properties of food powders in extrusion processing." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/38220.

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Master of Science
Department of Grain Science and Industry
Sajid Alavi
This study relates raw material particulate rheology to the granular flow in a single screw food extruder. Raw materials based on corn (i.e. meal, flour, and starch), wheat (i.e. farina, flour and starch), and sucrose (i.e. granulated, superfine, and powdered) were used as model particulate systems for the study. Various particulate-scale characteristics and flow parameters of these nine materials were determined using a powder rheometer. Properties such as basic flow energy, cohesion, flow function, and effective angle of internal friction were good indicators of flowability in an extruder. Corn meal exhibited lower energy requirements and a higher propensity for flow than corn flour (6.7mJ/g versus 10.7mJ/g, and “free-flowing” versus “cohesive,” according to Flow Function classifications), with wheat farina showing similar results when compared to wheat flour (5.8mJ/g versus 7.9mJ/g, and “highly free-flowing” versus “cohesive”), although both wheat systems showed lower energy requirements than their comparable corn systems. Sugar, being of a different base material and particle shape, behaved differently than these starch-based materials—flow energy decreased and propensity to flow increased as particle size decreased (51.7mJ/g versus 8.0mJ/g, and “free flowing” versus “highly free-flowing”). This large energy requirement for coarse sugar particles was attributed more to particle shape than composition, as the sharp edges of sugar can interlock and restrict movement through the sample. The starch-based results were validated in a particulate flow study involving the above model systems (corn meal, corn flour, wheat farina, and wheat flour) in a pilot-scale single screw extruder. Visualization data, obtained using a transparent plexiglass window during extrusion, confirmed that the flours exhibited higher flow energy requirements and a lower flow factor compared to coarser-particle size during extrusion, seen by the increased peak heights and barrel fill. Additionally, moisture changes were analyzed, showing an increase in energy required for starch-based materials as moisture increases and a decrease in energy for sucrose. Due to the hygroscopic nature of sucrose, moisture was absorbed more rapidly than starch products and the edges of individual particles softened, forming a soft solid. These physiochemical differences resulted in decreased energy requirements for sucrose as moisture was increased (51.7mJ/g to 13.6mJ/g), while corn meal and wheat farina yielded increased energy requirements (6.7mJ/g to 9.1mJ/g and 5.8mJ/g to 9.5mJ/g, respectively). Again, results of starch-based materials were validated using a plexiglass cover during extrusion, clearly showing an increase in barrel fill as moisture content increased for both materials, with corn meal flowing more readily than farina. Lastly, temperature of corn meal and farina was increased to show the difference in behavior of starch-based materials, where farina decreased in energy as temperature increased (14.4mJ/g to 12.1mJ/g ) while corn meal energy requirements increased (12.9mJ/g to 17.2mJ/g). With the results developed from these three experiments, and validated where physically possible, it was concluded that offline powder rheometry is a useful tool for predicting the behavior of food powders. These results were then developed into a computer-simulated model to allow for virtual and visual representation of the conveying action inside an enclosed steel barrel.

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Ellis, Matthew. "Simulations of magnetic reversal properties in granular recording media." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/12215/.

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With increasing demand for high density magnetic recording devices a paradigm shift is required to overcome the super-paramagnetic limit. By using a high anisotropy material, such as L1_0 FePt, and heat assisted magnetic recording the areal density can be taken well beyond 1 Tbit/in^2. For FePt the grains on which the data is stored can be reduced to 3nm in size before thermal noise becomes an issue. Therefore, the understanding of how magnetic grains of only a few nanometres in size behave and switch is highly important. Here an atomistic model of magnetic materials, based on the Heisenberg exchange interaction and localised classical atomic moments, is used to investigate the magnetic reversal properties of granular recording media. A detailed model for FePt, parametrised from ab-initio, is presented and this is used to investigate the finite size effects in nanometre grains. Using this model, the finite size effects on the linear reversal regime is investigated. Comparing a model using the Landau-Lifshitz-Bloch macrospin equation to the atomistic results show that multi-scale modelling may be valid down to the 3 nm length scale. The inter-granular exchange interaction between neighbouring grains is investigated using a model invoking the presence of magnetic impurities in the grain inter-layer. Using constrained Monte-Carlo methods the effective exchange is calculated for different impurity density, grain separation and temperature. Following this, helicity dependent all optical switching in granular FePt is investigated. The phase space for switching through the Inverse Faraday effect is explored. Using the Master equation, a model for thermal switching with magnetic circular dichroism is explored which qualitatively explains the induced magnetisation observed experimentally. Finally, the coupling of the spin and lattice system is modelled by combining spin and molecular dynamics. The coupling to the lattice excites magnons which appear to decay implying that some damping processes are occurring.

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Arowosola, Babatunde Clement. "Influence of particle-scale properties and gravitational field on flow properties of granular materials." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/13295/.

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The complexities in the processing behaviour of granular materials under different gravitational environments pose challenges to the researchers in a number of multidisciplinary fields. The micromechanical behaviour of granular materials is inherently heterogeneous due to its discrete nature. Generally, the macroscopic behaviour of granular materials can be determined by accounting for the inter-particle interactions that exist within. Although significant progress has been achieved in the past especially on the transport, handling and storage of granular materials in confined geometries under earth gravity using experimental and computational methods, the micromechanical behaviour of granular materials under low-gravitational environments is still poorly understood. Out of the several approaches proposed in the literature in understanding the complexities in granular materials, discrete element modelling (DEM) has evolved as an important tool in evaluating the role of particle scale properties on the flow and compaction characteristics of granular materials. The primary focus of this research is to understand the micromechanical properties of granular materials, primarily their flow and compaction characteristics under different gravitational environments. Hence, three dimensional DEM is applied in this study under earth, mars and lunar (EML) gravity conditions. In this study, in order to attain a fundamental level understanding of the flow behaviour of granular materials through confined geometries under varying gravity conditions, a comprehensive level of simulations were performed. Initially, sandstone materials as simulants used to represent space grains in space exploration activities are experimentally characterised to obtain two key input material parameters viz., particle size distribution and adhesion force between the grains. These key input parameters, in addition to their other physical properties reported in the literature are fed as input parameters in the three-dimensional DEM simulations for studying their flow and compaction characteristics under EML gravities. Further, investigations on the prediction of maximum shear stress distribution in a hopper containing granular materials under static filling were analysed under earth gravity using three dimensional DEM. The predicted results are compared with an advanced experimental approach using Photo-stress analysis tomography (PSAT). Studies show that the predicted DEM and experimental results for the maximum stress distribution are in good agreement under earth gravity. The hopper internal angle is seen to influence the stress profile quite significantly. Additionally, these DEM results agree qualitatively well with the common Walker’s theoretical predictions for the stress distribution along the hopper walls with dependence on hopper internal angle under earth gravity. The PSAT analysis, though performed only under earth gravity under static condition validates the usefulness of inputting measured particle-scale properties in the DEM simulations. Thereafter, different continuum approaches and DEM simulations are used to investigate the effect of particle scale properties and gravity on the flow characteristics of granular materials through hoppers. Continuum theories based on discrete layer approach and Kirya’s structural model for gravity effects on flow properties of grains in hoppers is performed and compared with that of DEM simulations. Most results obtained on the effect of various particle scale properties agree with existing studies in literature where available. Granular flow is seen to depend on gravity using both the continuum and DEM simulations and these results further agree qualitatively with predictions from a limited practical parabolic flight test operation. Based on this analysis and to further understand the influence of particle scale properties on granular flow, parametric analysis is carried out using DEM simulations. The analysis provides understanding of the complex behaviour of the grains and its response under EML gravity levels. Granular packing, granular bed density, cohesion, hopper geometry (orifice and internal angle), friction effect, angle of repose and combined adhesion strength and size distribution (for real samples) of the granular materials were all observed to have significant effect on granular flow under EML gravity levels distinctly. From all the analysis, the influence of gravity on granular flow is observed to be most sensitive under the lunar gravity. This could imply that the lunar in-situ resource utilization (ISRU) processes may require wider exit openings or non-gravity driving forces to have an effective output from the various processes as compared to process utilization on earth. To improve the granular flow, applying a granular flow aid is investigated for a horizontal piezo vibrator across the hopper containing granular bed under EML gravity levels using DEM. Analysis indicates that the piezo-vibrator technique could improve the flow of grains through a hopper under low gravity levels. To aid the design of the vibrator, its effective impact to improve flow is however shown to depend on the horizontal amplitude and frequency of the vibrator. Furthermore DEM simulations are performed to assess the quality of granular filling in a collection chamber from continuous flow and staggered flow outputs. Continuous flow mechanism is seen to be more effective in processing of grains as against staggering the flow especially under a low gravity level. Finally, the compaction properties of granular media with ice contents under different gravity levels is analysed using DEM simulations. Overall, this thesis presents vital information on the role of particle scale properties on flow and compaction characteristics of granular materials under varying gravity environments. In the future, the understandings reported in this thesis could help to design suitable flow and compaction processes in different engineering and science disciplines, especially in space/low gravity explorations to meet with the ever growing needs for technology advancements.

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Chen, Bingran. "Effects of Chemical Properties of Cyanotoxins on Transport through Granular Activated Carbons." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535374137804276.

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25

Roy, Debasis. "Mechanical properties of granular deposits from self-boring pressuremeter tests." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25149.pdf.

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26

Bouvier, Philippe. "The magnetic and magneto-optic properties of sputtered granular layers." Thesis, Coventry University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318531.

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27

Haeberle, Jan [Verfasser], and Matthias [Gutachter] Sperl. "Properties of Tailored Granular Media / Jan Haeberle ; Gutachter: Matthias Sperl." Köln : Universitäts- und Stadtbibliothek Köln, 2019. http://d-nb.info/1179356039/34.

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28

Gu, Xiaoqiang, and 顾晓强. "Dynamic properties of granular materials at the macro and microscales." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47752622.

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Dynamic properties of soil, including modulus and damping, play essential roles in evaluating the response of the soil deposit and its supporting structures when subjected to dynamic loads induced by earthquakes, traffic, explosions, machine foundations, and so on. It is well recognized that the dynamic properties of soil are affected by many factors, such as strain amplitude, stress condition, void ratio, saturation and gradation. Despite tremendous works have been done, the macroscopic effects of several key factors on the dynamic properties of granular material are not yet fully understood, due primarily to its particulate and multiphase nature. Furthermore, the understanding of how the influencing factors affect the dynamic properties of granular material or the underlying fundamental mechanism is inadequate. This study thus is carried out to investigate the effects and the underlying mechanisms of these important factors, including strain amplitude, stress condition, void ratio, particle size, saturation, and initial fabric, by means of advanced laboratory tests and numerical simulations. To study the dynamic properties at the macro scale, a series of laboratory tests are carried out in a state-of-art resonant column (RC) apparatus incorporating bender element (BE) and torsional shear (TS). Test materials include artificial glass beads with different sizes, commercially available standard sands and natural completely decomposed granite (CDG). The specimens are prepared at various densities, confined at different pressures, tested both in dry and saturated conditions, and reconstituted by different preparation methods. In particular, the characteristics of wave signals (both S-wave and P-wave) at various conditions and the associated interpretation methods in BE tests are investigated in detail. The results obtained from BE, RC and TS are compared to clarify the potential effect of test method. Moreover, attempts are made to explain the test results from the viewpoint of micromechanics. Numerical simulations using discrete element method (DEM) are performed to study the dynamic properties of granular materials and explore the underlying fundamental mechanism at the micro scale. The simulations indicate that the elastic properties are closely related to the coordination number and the distribution of normal contact forces in the specimen. The effects of initial fabric and induced fabric, which are respectively achieved by different specimen generation methods and the application of anisotropic stress states, are investigated. The anisotropy of the specimen and its evolution during shearing are also studied. The results indicate that the anisotropy is resulted from the spatial distributions of contact force and contact number. The modulus reduction curve and damping curve obtained from the simulations are compared with those from laboratory tests.
published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy

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29

Evans, T. Matthew. "Microscale Physical and Numerical Investigations of Shear Banding in Granular Soils." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7576.

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Under loading conditions found in many geotechnical structures, it is common to observe failure in zones of high localized strain called shear bands. Existing models predict these localizations, but provide little insight into the micromechanics within the shear bands. This research captures the variation in microstructure inside and outside of shear bands that were formed in laboratory plane strain and two-dimensional discrete element method (DEM) biaxial compression experiments. Plane strain compression tests were conducted on dry specimens of Ottawa 20-30 sand to calibrate the device, assess global response repeatability, and develop a procedure to quantitatively define the onset of localization. A new methodology was employed to quantify and correct for the additional stresses imparted by the confining membrane in the vicinity of the shear band. Unsheared and sheared specimens of varying dilatancy were solidified using a two-stage resin impregnation procedure. DEM tests were performed using an innovative servo-controlled flexible lateral confinement algorithm to provide additional insights into laboratory results. The solidified specimens were sectioned and the resulting surfaces prepared for microstructure observation using bright field microscopy and morphological analysis. Local void ratio distributions and their statistical properties were determined and compared. Microstructural parameters for subregions in a grid pattern and along predefined inclined zones were also calculated. Virtual surfaces parallel to the shear band were identified and their roughnesses assessed. Similar calculations were performed on the DEM simulations at varying strain levels to characterize the evolution of microstructure with increasing strain. The various observations showed that the mean, standard deviation, and entropy of the local void ratio distributions all increased with increasing strain levels, particularly within regions of high local strains. These results indicate that disorder increases within a shear band and that the soil within the shear band does not adhere to the classical concept of critical state, but reaches a terminal void ratio that is largely a function of initial void ratio. Furthermore, there appears to be a transition zone between the far field and the fully formed shear block, as opposed to an abrupt delineation as traditionally inferred.

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Артюхов, Артем Євгенович, Артем Евгеньевич Артюхов, and Artem Yevhenovych Artiukhov. "The prospects of granules getting with the specific properties in small-sized vortex devices." Thesis, Государственный институт подготовки и переподготовки кадров промышленности, 2011. http://essuir.sumdu.edu.ua/handle/123456789/26420.

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Найбільш простою у виробництві і застосуванні вибуховою речовиною є пориста аміачна селітра (ПАС). ПАС також є основою для виробництва інших вибухових речовин. Метою роботи є обґрунтування можливості створення в Україні сучасного високоефективного і економічного виробництва ПАС, яке в даний час відсутня. В результаті порівняльного аналізу споживчих властивостей отриманого безбаштовим способом продукту з російським аналогом показано, що утримуюча здатність ПАС по соляровій оливі коливається в межах 9-17% при міцності гранул до 500 гр/гранулу, а утримуюча здатність російського аналога - 6,8% при середній міцності гранул 300 гр / гранулу. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/26420
Наиболее простым в производстве и применении взрывчатым веществом является пористая аммиачная селитра (ПАС). ПАС также является основой для производства других взрывчатых веществ. Целью работы является обоснование возможности создания в Украине современного высокоэффективного и экономичного производства ПАС, которое в настоящее время отсутствует. В результате сравнительного анализа потребительских свойств полученного безбашенным способом продукта с российским аналогом показано, что удерживающая способность ПАС по солярового масла колеблется в пределах 9-17% при прочности гранул до 500 гр/гранулу, а удерживающая способность российского аналога - 6,8% при средней прочности гранул 300 гр/гранулу. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/26420
The most simple in manufacture and using of industrial explosive agent is porous ammonium nitrate (PAN). PAN is also a basic for production of other explosives. The purpose of the work is a feasibility study for the establishment in Ukraine of modern highly efficient and economical production of PAN, which is currently absent. As a result, the comparative study of consumer properties of the product received by no-tower method with the Russian analogue is shown that the keeping ability of PAN on solar oil ranges from 9-17% at the strength of granules to 500 g/granule, and the keeping ability of Russian analogue – 6,8% at average strength of granules 300 g/granule. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/26420

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31

O'Reilly, Michael Patrick. "Mechanical properties of granular materials for use in thermal energy stores." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353925.

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32

Neugebauer, Adam (Adam Halbert). "Thermal properties of granular silica aerogel for high-performance insulation systems." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85213.

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Thesis: S.M. in Building Technology, Massachusetts Institute of Technology, Department of Architecture, 2013.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 65-67).
Based on mounting evidence in support of anthropogenic global climate change, there is an urgency for developments in high-performance building techniques and technologies. New construction projects provide substantial opportunities for energy efficiency measures, but they represent only a small portion of the building stock. Conversely, while existing buildings are plentiful, they typically have a much narrower range of feasible energy efficiency options. Therefore, there will continue to be a need for the development of new and improved energy efficiency measures for new building construction and even more so for deep retrofits of existing buildings. This thesis provides an overview of the research performed into the on-going development at MIT of a high-performance panelized insulation system based on silica aerogel. Two test methods were used for measuring the thermal conductivity of the granules: the transient hot-wire technique and the guarded hot-plate system. Utilizing the hot-wire set-up, it was demonstrated that compressing a bed of granules will decrease the thermal conductivity of the system until a minimum point is reached around the monolithic density of the aerogel. For the Cabot granules, this was seen at 13 mW/m-K and about 150 kg/m3. The MIT granules showed equal performance to the Cabot granules at bed densities 20-30 kg/m3 lower. The hot-plate testing was able to experimentally evaluate previous analytical predictions regarding the conductivity impact of the internal panel truss and the under-prediction of radiant heat transfer in the hot-wire method. Hot-wire testing was also done in a vacuum chamber to quantify potential performance improvements at reduced air pressures. Since a vacuum would require the incorporation of a barrier film into the panel system, some analyses were done into the thermal bridging potential and gas diffusion requirements of such a film. Additionally, physical prototyping was done to explore how the film would be incorporated into the existing panel design. The aerogel-based insulation panel being developed at MIT continues to show promise, though there are still plenty of opportunities remaining in the development cycle.
by Adam Neugebauer.
S.M. in Building Technology

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33

Amitai, Shahar. "Statistical mechanics, entropy and macroscopic properties of granular and porous materials." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/54766.

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Granular materials are an intriguing phase of matter. They can support stresses like a solid, but can also flow down a slope like a liquid. They compress under tapping, but dilate under shearing. Granular materials have fascinated the research community for centuries, but are still not fully understood. A granular statistical mechanical formalism was introduced a quarter of a century ago. However, it is still very much a theory in evolution. In this thesis, we present a few developments of the theory, which make it more rigorous and testable. We adjust the original formalism by replacing the volume function by a more suitable connectivity function. We identify the structural degrees of freedom as the edges of a spanning tree of the contact network graph. We extend the formalism to include constraints on these degrees of freedom and correlations between them. We combine between this formalism and the better established stress ensemble, and then derive an equipartition principle and an equation of state, relating the macroscopic volume and boundary stress to the analogue of the temperature, the contactivity. This makes the theory testable by macroscopic measurements. We then address two application-orientated problems, involving the porous media made by consolidated granular materials. First, we present a scheme to design porous fuel cell electrodes such that the three-phase boundary (TPB) is maximised. These electrodes are made of sintered bi-disperse powders, and the longer their TPB the more efficient the fuel cell. Using a systematic analysis for a commonly used set of given constraints, we find optimal design parameters that yield a TPB that is three times longer than the conventional design under the same constraints. Then, we focus on transport in the pore space of such materials. We study the diffusion of finite-size particles in porous media, and what makes them anomalous. Having pinned-down the causes for sub-diffusion, we develop a continuous-time random walk-based model that predicts correctly the anomaly parameter.

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34

Tran, Duc Long. "Impact of intrinsic granular porosity on the durability properties of concrete." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30021.

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La préservation des ressources naturelles et la limitation des émissions de CO2 sont une contribution au développement durable. Dans le cadre de la conception du béton, cette contribution consiste à utiliser des granulats locaux ou recyclés. Cependant, ces derniers peuvent être poreux et de faible qualité. La communauté scientifique est d'accord sur le fait que la porosité intrinsèque des granulats modifie les propriétés de transport du béton, mais dans quelle mesure reste une question. L'objectif de la thèse est d'analyser l'impact de la porosité intrinsèque des granulats grossiers, principalement sur les propriétés de durabilité du béton. Dans une compréhension préliminaire et en vue d'accentuer les phénomènes se produisant dans le béton, un programme expérimental est conçu pour le modèle élémentaire (EM), qui est composé de pâte et de gravier. L'impact de la nature des granulats (poreux et non poreux), de l'état d'humidité et du volume ainsi que de la nature du liant, est analysé sur i) la porosité de l'eau du modèle élémentaire, ii) la structuration de l'interface pâte-granulat. Ensuite, à l'échelle du béton, les matériaux ont été conçus avec le même squelette de granulats (même sable) et la même teneur équivalente en liant. Les conceptions variaient selon la nature des granulats, l'état d'humidité, la nature du liant, la variation du rapport eau/ciment et l'incorporation d'adjuvants chimiques (plastifiant ou superplastifiant). L'impact de la porosité des granulats grossiers sur les propriétés à l'état frais (affaissement, densité apparente et teneur en air emprisonné) et à l'état durci (résistance à la compression, porosité de l'eau, absorption d'eau, perméabilité aux gaz, migration des chlorures, carbonatation accélérée et teneur en portlandite) a été étudié. Les principaux résultats montrent que l'état d'humidité des agrégats et la nature du liant sont les premiers facteurs qui conditionnent la structuration de l'interface pâte/agrégats au sein du modèle élémentaire. La nécessité d'utiliser des agrégats poreux en surface saturée et sèche est particulièrement mise en évidence. À l'échelle du béton, les propriétés à l'état frais sont influencées par la porosité des granulats et le rapport eau/liant (W/B). Cependant, pour un rapport eau/liant fixe correspondant à une consistance fluide, les variations des propriétés à l'état frais mesurées lors de l'incorporation de granulats poreux ne dépendent pas de la nature du liant. Dans le béton durci, la porosité des granulats joue un rôle important dans la porosité de l'eau et la perméabilité à l'air du béton, quelle que soit la nature du liant. Pour les autres propriétés de durabilité (absorption d'eau, migration de Clo, carbonatation et résistance à la compression), la nature du liant l'emporte sur la porosité des granulats
The preservation of natural resources and the limitation of CO2 emissions are a contribution to sustainable development. In the context of the concrete design, this contribution consists in using local or recycled aggregates. However, local or recycled aggregates can be porous and of low quality.The scientific community agrees that the intrinsic porosity of aggregates changes the transport properties of concrete, but to what extent is still a question. The objective of the thesis is to analyze the impact of intrinsic coarse aggregate porosity on mainly the durability properties of concrete. In a preliminary understanding and with a view to accentuating phenomena occurring in the concrete, an experimental program is designed for elementary model (EM), which is composed of paste and gravel. The impact of the aggregate nature (porous and non-porous), moisture state and volume together with the binder nature, is analyzed on i) the water porosity of EM, ii) the structuration of the paste-aggregate interface. Next, at concrete scale, materials were designed with the same skeleton of aggregates (same sand) and the same equivalent binder content. The designs varied by the aggregate nature, moisture state, the binder nature, the variation of water/cement ratio and the incorporation of chemical admixtures (plasticizer or superplasticizer). The impact of coarse aggregate porosity on properties in the fresh state (slump, apparent density and entrapped air content) and in the hardened state (compressive strength, water porosity, water absorption, gas permeability, chloride migration, accelerated carbonation and Portlandite content) was studied. The main results show that the moisture state of aggregate and the binder nature are the first factors that condition the structuring of the paste/aggregate interface within the elementary model. The necessity to use porous aggregates in saturated surface dry is particularly highlighted. At the scale of concrete, the properties in the fresh state are influenced by the aggregate porosity and the water/binder (W/B) ratio. However, for a fixed W/B ratio corresponding to fluid consistency, the variations in the fresh properties measured when porous aggregates are incorporated do not depend on the binder nature. In hardened concrete, porosity of aggregate plays an important role in water porosity and air permeability of concrete whatever the nature of binder. For other durability properties (water absorption, Clo migration, carbonation and compressive strength), the nature of binder overcome leading in comparison to the porosity of aggregate

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35

Hughes, Graeme David. "The dynamical properties of percolating structures." Thesis, Lancaster University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302931.

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To, Chiu-yin, and 杜昭彥. "A unified elasto-plastic model for saturated loosely compacted completely decomposed granite." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203554.

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37

Shertzer, Richard Hayden. "Fabric tensors and effective properties of granular materials with application to snow." Diss., Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/shertzer/ShertzerR0811.pdf.

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Granular materials e.g., gravel, sand, snow, and metallic powders are important to many engineering analysis and design problems. Such materials are not always randomly arranged, even in a natural environment. For example, applied strain can transform a randomly distributed assembly into a more regular arrangement. Deviations from random arrangements are described via material symmetry. A random collection exhibits textural isotropy whereas regular patterns are anisotropic. Among natural materials, snow is perhaps unique because thermal factors commonly induce microstructural changes, including material symmetry. This process temperature gradient metamorphism produces snow layers that can exhibit anisotropy. To adequately describe the behavior of such layers, mathematical models must account for potential anisotropy. This feature is absent from models specifically developed for snow, and, in most granular models in general. Material symmetry is quantified with fabric tensors in the constitutive models proposed here. Fabric tensors statistically characterize directional features in the microstructure. For example, the collective orientation of intergranular bonds impacts processes like conduction and loading. Anisotropic, microstructural models are analytically developed here for the conductivity, diffusivity, permeability, and stiffness of granular materials. The methodology utilizes homogenization an algorithm linking microscopic and macroscopic scales. Idealized geometries and constitutive assumptions are also applied at the microscopic scale. Fabric tensors tying the granular arrangement to affected material properties are a natural analysis outcome. The proposed conductivity model is compared to measured data. Dry dense snow underwent temperature gradient metamorphism in a lab. Both the measured heat transfer coefficient and a developing ice structure favored the direction of the applied gradient. Periodic tomography was used to calculate microstructural variables required by the conductivity model. Through the fabric tensor, model evolution coincides with measured changes in the heat transfer coefficient. The model also predicts a different conductivity in directions orthogonal to the gradient due to developing anisotropy. Models that do not consider directional microstructural features cannot predict such behavior because they are strictly valid for isotropic materials. The conclusions are that anisotropy in snow can be significant, fabric tensors can characterize such symmetry, and constitutive models incorporating fabric tensors offer a more complete description of material behavior.

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Al-Awad, Khabeer. "The effect of biological exudates on the mechanical properties of granular soil." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/110599/.

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This study explores how biological processes can be used to enhance the geotechnical characteristics (shear and permeability data) of soils. In particular, the creative use of microbial substances to efficiently improve the mechanical properties (shear parameters) of soils is studied. The research studies give an excellent opportunity for understanding the principles of biological processes in geotechnical engineering development. Specifically, biofilm behaviour is a part of the interactions between geotechnical engineering and the biological process of microorganism growth. The main research questions of this study are how biofilm affects the shear parameters of granular soil under low normal stresses. To that end, this study concerns experimental work to explore the effect of accumulated bacterial biopolymer (biofilm) on the shear response of well-graded silica sand. A comparison is achieved between biotreated samples with un-biotreated samples as well as comparing with clean dry and saturated samples under the various testing conditions are considered. To address the objectives of this study, experimental work was conducted using an adapted direct shear test procedure that enables proper tests to investigate the impact of biofilm on the shear strength in a saturated condition. Moreover, these tests were performed at a displacement rate of 0.5 mm/min, and at various normal stresses (1.0, 4.1, 8.89, 16.2, and 25.0 kPa). The soil samples (defined as biotreated samples) were prepared to encourage biofilm growth and the production of exopolymeric substances (EPS) by supplying a glucose rich nutrient. The control samples produced by delivery of a glucose free nutrient (defined as standard samples). All samples were prepared and tested in triplicate. Furthermore, this study VI explain the influence of the biofilm on a poorly graded silica sand and a sea sand. The effect of various testing rates on the biotreated and standard sample was also investigated. The important finding of this study was that the potential impact of biofilm on densification on preloading biotreated sand samples. The growth of biofilm increases the ability of samples to densify under applied normal stress during incubation period compared with control samples. All biotreated samples show larger peak stress than the shear stresses of standard specimens. These differences may be because of the differences of loss on ignition content in both sample types. A biotreated sample contains higher biomass than that in the standard samples. The amount of formed biofilm in the biotreated poorly-graded silica sand and sea sand was significantly more than in the well-graded silica sand. This biofilm has had a similar effect on peak stress of both the well and poorly graded.

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Jones, Jay Walter IV. "An examination of scale-dependent electrical resistivity measurements in Oracle granite." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184887.

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Geotechnical characterization of crystalline rock is often dependent upon the influence of the rock's fracture system. To test ensemble fracture behavior in situ, a series of cross-hole and single-hole electrical conductivity measurements were made within saturated Oracle granite. The tests were conducted with a point source and a point reference electrode and employed electrode separations ranging from 8 inches to over 100 feet. A volume of rock approximately 50 x 50 x 150 feet was tested (as bounded by the vertical test borings). Analysis of the data in terms of an equivalent homogeneous material showed that the effective electrical conductivity increased with electrode separation. The cross-hole data indicate that the rock can be treated as a non-homogeneous, isotropic material. Further, the spatial variation of measured conductivities along a line can be fit to a fractal model (fractional Brownian motion), implying that the scale-dependence is a result of a fractal process supported by the fracture system. Scale-dependence exists at the upper scale limit of the measurements, hence a classical representative elemental volume was not attained. Two directions were taken to understand the scale-dependence. The rock mass is treated in terms of a disordered material, a continuum with spatially varying conductivity. First, a percolation-based model of a disordered material was examined that relates the conductivity pathways within the rock to the backbone of a critical percolation cluster. Using the field data, a fractal dimension of 2.40 was derived for the dimensionality of the subvolume within the rock that supports current flow. The second approach considers an analytic solution for a non-homogeneous, isotropic material known as the alpha center model (Stefanescu, 1950). This model, an analytic solution for a continuously varying conductivity in three dimensions, is a non-linear transform to Laplace's equation. It is employed over a regular grid of support points as an alternative to spatially discretized (piece-wise continuous) numerical methods. The model is shown to be capable of approximating the scale-dependent behavior of the field tests. Scaling arises as a natural consequence of the disordered electrical structure caused by the fracture system.

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40

Gamon, T. I. "The influence of weathering on the engineering properties of the Hong Kong Granite." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370155.

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Шабельник, Юрій Михайлович, Юрий Михайлович Шабельник, Yurii Mykhailovych Shabelnyk, Ірина Володимирівна Чешко, Ирина Владимировна Чешко, Iryna Volodymyrivna Cheshko, Ірина Михайлівна Пазуха, et al. "Electrophysical Properties of Granular Film Alloys Based on Fe and Ag or Au." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42780.

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The experimental results of electrophysical properties of granular film alloys based on Fe and Ag or Au are presented. It is established that the value of the temperature coefficient of resistance depends on the total thickness of the samples and the concentration of magnetic component. The components concentration in the system is shown to affect the formation of the solid solution and the granular film alloy. The optimal concentration value of Fe, in which the thermally stable solid solution forms, is 45 at. %.

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42

Gumbe, Lawrence O. "Mechanical properties of granular materials as related to loads in cylindrical grain silos." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1203011493.

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Gumbe, Lawrence Otweyo-Migire. "Mechanical properties of granular materials as related to loads in cylindrical grain silos /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541710474.

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44

Rahmanian, Nejatollah. "Influence of Scale-up of High Shear Mixer Granulators on the Evolved Structure and Properties of Granules." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515389.

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45

Mahmoodi, Foad. "Compression Mechanics of Powders and Granular Materials Probed by Force Distributions and a Micromechanically Based Compaction Equation." Doctoral thesis, Uppsala universitet, Institutionen för farmaci, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171874.

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The internal dynamics of powder systems under compression are as of yet not fully understood, and thus there is a necessity for approaches that can help in further clarifying and enhancing the level of understanding on this subject. To this end, the internal dynamics of powder systems under compression were probed by means of force distributions and a novel compaction equation. The determination of force distributions hinged on the use of carbon paper as a force sensor, where the imprints transferred from it onto white paper where converted through calibration into forces. Through analysis of these imprints, it was found that the absence of friction and bonding capacity between the particles composing the powder bed had no effect on how the applied load was transferred through the system. Additionally, it was found that pellet strength had a role to play in the homogeneity of force distributions, where, upon the occurrence of fracture, force distributions became less homogenous. A novel compaction equation was derived and tested on a series of systems composed of pellets with differing mechanical properties. The main value of the equation lay in its ability to predict compression behavior from single particle properties, and the agreement was especially good when a compact of zero porosity was formed. The utility of the equation was tested in two further studies, using a series of pharmaceutically relevant powder materials. It was established that the A parameter of the equation was a measure of the deformability of the powder material, much like the Heckel 1/K parameter, and can be used as a means to rank powders according to deformability, i.e. to establish plasticity scale. The equation also provided insights into the dominating compression mechanisms through an invariance that could be exploited to determine the point, at which the powder system became constrained, i.e. the end of rearrangement. Additionally, the robustness of the equation was demonstrated through fruitful analysis of a set of diverse materials. In summary, this thesis has provided insights and tools that can be translated into more efficient development and manufacturing of medicines in the form of tablets.

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Karmakar, Somnath [Verfasser], and Ralf [Akademischer Betreuer] Seemann. "Experimental investigations of mechanical properties of wet granular materials / Somnath Karmakar. Betreuer: Ralf Seemann." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2014. http://d-nb.info/1072418525/34.

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47

Newton, Nichola. "Preparation and properties of granular ferric hydroxide as an adsorbent in potable water treatment." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/7866.

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Three iron oxide materials have been studied for uptake of three anions (arsenate, phosphate and fluoride) and a cation (cadmium) from aqueous solutions. Two of the materials were produced using original procedures developed at Loughborough University. The former material was conditioned by a controlled freeze-thaw procedure to enhance granularity and the latter was air-dried at room temperature. Their capacities were compared with a commercially available material supplied by GEH Wasserchemle, Germany. Pore size distributions and specific surface area values were determined by N2 analysis at 77 K. All samples possessed a reasonable specific surface area, in the range 200-300 m2/g and were mesoporous. Samples produced at Loughborough University also contained some macropores, evidence of a more amorphous structure or lack of pH control during production. X-ray diffraction indicated that all samples had some b-FeOOH present and that the chloride content and production pH affected the material crystallinity. Crystallinity increased with increasing chloride content and a higher production pH resulted in the presence of more than one phase. Chemical characterisation was also completed on all three samples. The point of zero net proton charge and isoelectric point for each material was obtained by potentiometric batch titrations and zeta potential measurements respectively. The difference in these values increased with a higher chloride content and all samples studied possessed a positive surface at low pH and negative surface at high pH. These parameters were not greatly affected by the background electrolyte concentration, implying that the background electrolyte is not specifically adsorbed. However, arsenate and phosphate appeared to be specifically adsorbed as the isoelectric point decreased. The uptake capacities for arsenate, phosphate. fluoride and cadmium of all three samples were obtained by measuring batch isotherms at 25 degrees C. The pH range was 4-9, using various initial concentrations up to a maximum of approximately 30 uM. For all anionic species studied, the capacity decreased with increasing pH, and the reverse trend was noted for cadmium. The Langmuir model provided a good fit for the anionic isotherms and the Freundlich model for the cationic isotherms. The materials studied possessed a markedly higher capacity for fluoride than arsenate and phosphate, with an intermediate capacity for cadmium. This indicates that fluoride is attached to the surface via monodentate (single) bonds, whilst both arsenate and phosphate are primarily attached to the surface via bidentate (two) bonds. Cadmium is probably bound by both these mechanisms. The effect of competing anions on arsenic uptake capacity was determined using mini-column experiments of binary (arsenate-fluoride, arsenate-Phosphate and phosphate-fluoride) and ternary (arsenate-fluoride-phosphate) mixtures. Arsenate removal was strongly affected by the presence of phosphate, but was only slightly lower in the presence of fluoride. (Continues...).

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Yan, Luke, Rongrong Huang, Jian Xiao, Huiyun Xia, Min Chao, and Sven Wieβner. "Preparation and properties of a composite made by barium sulfate-containing polytetrafluoroethylene granular powder." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35550.

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Barium sulfate (BaSO₄)-containing polytetrafluoroethylene (PTFE) granular powder was prepared through a two-phase emulsion dispersion granulation method. Because of its large bulk density, small average particle size, narrow particle size distribution, and superior powder flowability, the granular powder is suitable for use in automatic molding machines. The effects of granulation on the tensile strength of the BaSO₄/PTFE composite were investigated, and the composite’s microstructures were characterized and analyzed using scanning electron microscopy. All these indicated that the granulation could make BaSO₄ disperse more homogeneously in PTFE and reduce many defects in molded articles. So the properties of the BaSO4/PTFE composites made by the granular powder were superior to the composite obtained from the nongranular powder. The tensile strength and elongation of the composite obtained from the granular powder could be achieved to a level of 19.4 MPa and 420%, respectively.

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Ansharullah, of Western Sydney Hawkesbury University, Faculty of Environmental Management and Agriculture, and School of Food Science. "Characterisation and extrusion of Metroxylon sago starch." THESIS_FEMA_SFS_Ansharullah_X.xml, 1997. http://handle.uws.edu.au:8081/1959.7/490.

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The study presented here was firstly to investigate the physiochemical properties of native sago starch (obtained from Metroxylon sp. and designated as sago INA), in comparison with those of Metroxylon sago starch obtained from a different source, sago starch derived from Arenga sp. palms, wheat, corn, and tapioca starches. The properties analysed were chemical composition, total starch content, apparent amylose content, pasting properties, endothermic thermal behaviour, starch paste clarity, freeze-thaw stability, hardness of gel, and microscopic structure of the granules. The results obtained indicated that sago INA starch sample contained less fat and protein, compared to cereal starches. The sago starch sample had larger sized granules and had a more transparent paste. The gels of the starch were harder, and showed a relatively better stability to freeze-thaw treatment. The other part of the study was extrusion of sago INA starch both in the absence and presence of enzyme by utilising a response surface design. In the absence of the enzyme, the experiment was conducted to establish the extrusion process conditions including moisture contents, melt temperature, and screw speed. The extruded products were then analysed for degree of molecular degradation, light microscopic structure, reducing sugars of the water soluble materials, water absorption index, water solubility index, enzyme susceptibility, and gelatinisation endothermic energy. Increased mechanical and thermal energy input received by the products in the extruder resulted in a significant degradation of the molecular weight of the macromolecules. Light photomicrographs also suggested that the granule structures of the extrudates have been reshaped. All extrudate samples had a very low gelatinisation endothermic energy compared to its native starch. The specific mechanical energy received by the products in the extruder was calculated and related to the process variables. The possibility of using the products in food application was also discussed.
Doctor of Philosophy (PhD)

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50

Chmelar, Juraj. "Size Reduction and Specification of Granular Petrol Coke with Respect to Chemical and Physical Properties." Doctoral thesis, Norwegian University of Science and Technology, Department of Geology and Mineral Resources Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1719.

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Carbon required for the reduction of alumina by electrolysis in the Hall-Héroult process is supplied by the anode. Anodes are produced from a mixture of petroleum coke with coal tar pitch as the binder. The minimum theoretical carbon consumption is 0.334 kg C/kg Al. But due to current efficiency and oxidation losses the consumption is typically 400 kg C/kg Al.

Petroleum coke is a by-product from crude oil refineries, but as its value represents only about 2 per cent of the overall production it has a limited interest to the producers. Mechanical and physical properties of coke are influenced by the crude oil, processes within the refineries and calcining of the coke. Continuous high demand for calcined coke by aluminium smelters has created a difficult situation with respect to quality and availability, leading to the use of lower quality coke in aluminium smelters and potential disturbances in the production.

Understanding the consequences of varying calcined coke qualities is crucial for to possibly compensate and adjust process parameters in the subsequent use of the coke, in order to obtain economical production of aluminium.

In the present work, the subject of study was four different petroleum coke types, where three were derived from a single source (SSA, SSB and SSC) and one was from a blend of different cokes. All of the cokes had different chemical and physical properties. Single source cokes have homogenous chemical and physical composition in the whole size range while the blended coke had heterogeneous composition due to the mixture of different coke types used. The blended coke consisted of several different coke types (25) in order to meet the required specification.

This work also describes new characterisation/measurement methods which can contribute to a better understanding of variations in material properties due to physical and mechanical changes in the calcined coke feed materials.

Each step in the production of pilot scale anodes is described. A new method was developed for the characterisation of the mechanical strength of calcined coke. This method, the drop test, originates from the study of materials for road construction for the determination of the grain stability of rock materials. The method determines the coke grain strength in the entire size distribution. On the other hand, established measuring methods for calcined coke, HGI (ASTM D5003-95) and grain stability (ISO 10142), determine only the mechanical strength in a specific size range, +0.6-1.18 mm and +4-8 mm, respectively. In other words, both methods give limited information about coke mechanical strength distribution throughout the whole size range, which is especially important when blended cokes are used. Additionally, the results from the drop test are expressed in volume reduction, size reduction, impact force and amount of fines below 148 μm generated during the test. A good correlation between ISO 10142 and the drop test was found. The results show good correlation between the size and volume reduction and the specific grinding energy. The method can also determine the grain strength of a specific size fraction which might be critical to further processing during anode production.

Totally, about 8 tons of four calcined coke types were processed during this work. The majority of this material was ground in the air swept ball mill, for production of the finest fraction, dust. The pilot scale air swept ball mill circuit is identical to the equipment used in industry today. This investigation showed the importance of process optimisation for the stable production of dust with the required specification (particle size and Blaine). Each coke exhibited different behaviour in the grinding circuit, due to different mechanical strengths, which is reported as a specific grinding energy. The mechanically weakest coke produced dust with the lowest specific grinding energy. The particle size variation in the coke used in the mill produced a significant disturbance in the product quality. It was found that the sweeping speed through the mill influences the particle size distribution in terms of the proportion of the finest particles. It also affected the particle roundness of the produced dust, which can influence the flowability of the coke when mixed with pitch. The ratio of ball sizes and the rotational speed of the mill influenced the particle size distribution, Blaine and specific grinding energy.

On-line particle size control was utilised during the dust production. This system allowed continuous control of the product size by regulation of the air classifier rotor speed. Three different dust sizes were produced in the air swept ball mill, which were all below about 200 μm but contained different proportions of material below 63 μm.

Sieved coke fractions together with dust were weighed according to a specified recipe and blended in a sigma blade mixer together with coal tar pitch. A vibration compactor was used for the production of green anodes under optimal conditions. The anodes were produced with three different pitch contents (15, 18 and 20 wt%) and three different dust sizes (45, 63 and 94 %, -63 μm).

Core samples of green anodes were investigated in an improved dilatometer for the determination of thermal expansion and shrinkage during baking. Improvements made to the dilatometer during this work contributed to better reproducibility, increased precision and a healthier working environment. An increase in the heating rate influenced the initial expansion, shrinkage and baking loss of the anode. The heterogeneous pitch distribution throughout the anode due to the forming force, friction between coke particles and between the paste and mould showed the importance of selecting a consistent sampling position. The results showed that the bottom samples have greater expansion due to a thicker pitch bridge layer while the top samples have reduced expansion. The sample packing material contributed to a higher initial expansion due to the reduced free surface area for binder volatiles release, and the shrinkage was reduced because of the radial thrusts from the packing material. Thermal dilation results showed differences between samples with varying pitch, dust size and coke type, which can be used to indicate the final properties of baked anodes. A good correlation was found between the thermal dilation after the pitch expansion and the dust content.

Green anodes were baked under controlled conditions and then characterised. The baked apparent density showed a good correlation with the pitch content and dust size. The results showed that 18 % pitch content and 63 % -63 μm produced the highest baked densities. The variation in coke type exhibited differences in baked density, specific electrical resistance, air permeability, CO2 and air reactivity and modulus of elasticity.

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Dissertations / Theses on the topic 'Granule properties'

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