Volcanoes are dynamic evolving structures, with life cycles that are punctuated by episodes of flank instability. Putauaki (Mount Edgecumbe) is a stratovolcano located onshore in the Bay of Plenty, New Zealand. The aim of this study was to assess the stability of Putauaki and analyse the risk associated with volcanic collapse. To achieve this objective, a multidisciplinary approach was used, incorporating geomorphological and geological mapping, rock mass classification, laboratory testing to identify geotechnical properties of materials representative of the volcano, stability modelling, and analysis of landslide run-out zones. Putauaki comprises two predominant features including the larger and younger Main Cone (the summit lying 820 m a.s.l., slope angles up to 36 ), and smaller and older Main Dome (the summit lying 420 m a.s.l., slope angle of 24 ). Both features show little evidence of erosion or surface water. Rock mass description defined six lithotechnical units including indurated andesite, indurated dacite, scoriaceous andesite, altered andesite (all categorised as hard rocks), and block and ash flow and Matahina Ignimbrite (both categorised as soft rocks). The uniaxial compressive strength (UCS) of indurated andesite and indurated dacite was 60 4 MPa and 44.7 0.9 MPa respectively, correlating with moderately strong rock. Discontinuities of the indurated units were widely spaced, showed medium persistence and wide aperture, and were slightly weathered. Infill comprised predominantly loosely packed, very strong, coarse gravel. UCS of scoriaceous andesite and altered andesite was 25 5 MPa and 15 1 MPa respectively, allowing categorisation as very weak rock. Discontinuities of scoriaceous andesite were widely spaced, showed high persistence and wide aperture, and were moderately weathered. Discontinuities of the altered andesite were moderately spaced, showed low persistence and wide aperture, and were highly weathered. Infill of scoriaceous and altered andesite was loosely packed, moist, weak to very weak medium gravel. The block and ash flow was a poorly sorted, loosely packed, sandy, gravely and cobble rich matrix supported deposit. The Matahina Ignimbrite was a very weak, discontinuity-poor deposit. Shear box testing indicated cohesion and friction angle of 0 MPa and 42.1 (block and ash flow) and 1.4 x 10-3 MPa and 41.7 (Matahina Ignimbrite) respectively. These values are similar to published values. Correlation of each lithotechnical unit to its respective rock mass description site allowed approximate boundaries of each unit to be mapped. Each unit's mass strength was combined with measured bulk densities and incorporated into two dimensional slope profiles using the stability modelling package GalenaTM. Ten slope profiles of Putauaki were constructed. Failure surfaces for each slope profile were defined using the Bishop simplified multiple analysis method. Four slope profiles showed the potential for small scale failure (less than 0.1 km2 of material). The remaining six slope profiles showed the potential for large scale failure (greater than 0.1 km2 of material). Stability of these six slope profiles was investigated further in relation to earthquake force, watertable elevation, and a disturbance factor of the rock mass (D). Conditions of failure graphs for profile 6a showed that at low D (less than 0.4), earthquake forces and watertable elevation must be unrealistically high for the region (greater than 0.33 g; greater than 15% watertable elevation) in order produce a factor of safety less than 1. The remaining five slope profiles showed potential to be unstable under realistic earthquake forces and watertable elevations. Two of these profiles were unable to achieve stability at D greater than 0.8 (profile 4) and D greater than 0.9 (profile 5). A D value of 0.6 (intermediate between 0.4 and 0.8) is argued to most realistically represent Putauaki. The fact that Putauaki has not undergone large scale failure to date supports the conclusion that the constructed models overestimate the influence of those factors which promote slope instability. Maximum and minimum landslide run-out zones were constructed for the slope profiles exhibiting the potential for large scale failure. Definition of the position and extent of maximum and minimum run-out zones assumed H/L (fall height to run-out length) ratios of 0.09 and 0.18 respectively, as well as the 'credible flow path' concept. Identified impacts of landslides sourced from Putauaki include inundation of Kawerau Township, Tarawera River, forestry operations, road networks, and power supplies. Based on these impacts, the risk posed by landslides from each slope profile was categorised as ranging from relatively low to relatively high. Landslides sourced from the south-west flanks pose a relatively low risk due to their prerequisite of unrealistically high watertable elevations and earthquake forces. Landslides sourced from the north-west flanks pose a relatively high risk as minimum run-out will inundate north-east parts of Kawerau Township. Landslides sourced from the eastern flanks pose a moderate risk due to their run-out zones avoiding Kawerau Township.

Statics, dynamics, rheology and scission-recombination kinetics of self-assembling linear micelles are investigated at equlibrium state and under shear flow by computer simulations using a newly proposed mesoscopic model. We model the micelles as linear sequences of Brownian beads whose space-time evolution is governed by Langevin dynamics. A Monte Carlo algorithm controls the opening of a bond or the chain-end fusion. A kinetic parameter omega modelling the effect of a potential barrier along a kinetic path, is introduced in our model. For equilibrium state we focus on the analysis of short and long time behaviors of the scission and recombination mechanisms. Our results show that at time scales larger than the life time of the average chain length, the kinetics is in agreement with the mean-field kinetics model of Cates. By studying macroscopic relaxation phenomena such as the average micelle length evolution after a T-jump, the monomer diffusion, and the zero shear relaxation function, we confirm that the effective kinetic constants found are indeed the relevant parameters when macroscopic relaxation is coupled to the kinetics of micelles. For the non-equilibrium situation, we study the coupled effects of the shear flow and the scission-recombination kinetics, on the structural and rheological properties of this micellar system. Our study is performed in semi-dilute and dynamically unentangled regime conditions. The explored parameter omega range is chosen in order for the life time of the average size chain to remain shorter than its intrinsic (Rouse) longest relaxation time. Central to our analysis is the concept of dynamical unit of size Lambda, the chain fragment for which the life time tau_Lambda and the Rouse time are equal. Shear thinning, chain gyration tensor anisotropy, chain orientation and bond stretching are found to depend upon the reduced shear rate Beta_Lambda=gamma dot*tau_Lambda while the average micelle size is found to decrease with increasing shear rate, independently of the height of the barrier of the scission-recombination process.

none

Nonlocal equations for coupled heat and mass transport are developed within the Green-Kubo formalism. Nonlocal thermal transport in Lennard-Jones solids is computed to establish the existence of semi-ballistic transport. Deviations from the diffusive theory are shown by comparing the Fourier transform of the response function from the nonlocal theory to that of the diffusive one. It is shown that the deviations from the local theory correspond to acoustic phonons, whose frequency dependence gives rise to the observed deviations from the local theory.

Dins dels processos de recuperació de metalls de dissolucions diluïdes s'ha realitzat un estudi del procés d'extracció d'or i de zinc mitjançant resines amberlite XAD-2 impregnades amb sulfur de triisobutil fosfina (TIBPS) i àcid di-(2-etilhexil) fosfòric (DEHPA) respectivament.S'ha realitzat un estudi de l'equilibri de l'adsorció d'espècies metàl·liques d'aquests metalls amb les resines indicades anteriorment. Amb la metodologia emprada per a la determinació dels punts d'equilibri dels experiments en batch i en columna, s'ha vist que una única isoterma no podia descriure el fenomen global d'equilibri i que en funció de la metodologia emprada s'obtenien isotermes diferents.Es va introduir una nova variable per poder explicar el fenomen observat, i per tant, amb aquesta nova variable l'equació de la isoterma es converteix amb l'equació d'una supèrfície que s'ha definit com a Superfície d'Equilibri.S'han determinat les equacions de les Suprfícies d'Equilibri dels sistemes d'adsorció estudiats (Au(III) TIBPS/XAD-2 i Zn(II) DEHPA/XAD-2) observan una bona coincidència de tots els punts d'equilibri obtinguts sobre la superfície, així com, un bon ajust de totes les isotermes obtingudes en funció de les diferents metodologies emprades sobre les respectives superfícies d'equilibri. Aquest nou concepte generalitza el concepte d'isoterma d'un procés d'adsorció.Fimalment, s'ha plantejat un model matemàtic d'adsorció per a determinar el coeficient efectiu de difusió (De) i el coeficient de transferància de matèria (kf) per ambdós sistemes d'adsorció estudiats mitjançant l'aplicació del model de difusió de sòlid homogeni (HSDM), utilitzant com a condició de contorn en el model la isoterma de Langmuir obtinguda mitjançant els experiments en columna de llit fix i emprant també l'equació obtinguda mitjançant el nou concepte de Superfície d'Equilibri.Els resultats obtinguts són molt satisfactoris, per tant, es pot concloure que la Superfície d'Equilibri és una bona eina per a descriure l'equilibri en els processos d'adsorció d'or i zinc amb les resines amberlite XAD-2 impregnades amb TIBPS i DEHPA respectivament. / The study of the extraction process of gold and zinc with Amberlite XAD-2 resins impregnated with tri-isobutylphosphine sulfide(TIBPS) and di-(2-ethylhexyl) phosphoric acid (DEHPA), respectively, has been studied.The equilibria governing the metallic ions adsorption by the studied systems have been established. Taking into account the methodology used to get the equilibria points corresponding to batch and column experiments performed, it was noticed that a unique isotherm could not describe the global equilibrium and that different isotherms were obtained in function of the experimental methodology carried out.It was introduced a new variable for explaining the phenomenon observed. By doing this, the isotherm became a surface that it was called equilibrium isotherm.The equations corresponding the Equilibrium Surfaces of the adsorption systems studied (Au(III) / TIBPS-XAD-2 and Zn(II) / DEHPA-XAD-2) were determined. The equilibria points obtained by batch and column experiments as well as obtained isotherms were very well placed on the surface. Thus, this new concept generalises the concept of isotherm in an adsorption process. Finally, the homogeneous solid diffusion model (HSDM) was applied for performing an adsorption mathematical model for determining the effective diffusion coefficient (De) and the mass transfer coefficient (kf) of both studied systems. The obtained results were very successful, so, it can be concluded that the Equilibrium Surface is a very good tool for describing the equilibria of the studied adsorption processes.

Statics, dynamics, rheology and scission-recombination kinetics of self-assembling linear micelles are investigated at equlibrium state and under shear flow by computer simulations using a newly proposed mesoscopic model. We model the micelles as linear sequences of Brownian beads whose space-time evolution is governed by Langevin dynamics. A Monte Carlo algorithm controls the opening of a bond or the chain-end fusion. A kinetic parameter omega modelling the effect of a potential barrier along a kinetic path, is introduced in our model.<p>For equilibrium state we focus on the analysis of short and long time behaviors of the scission and recombination mechanisms. Our results show that at time scales larger than the life time of the average chain length, the kinetics is in agreement with the mean-field kinetics model of Cates. By studying macroscopic relaxation phenomena such as the average micelle length evolution after a T-jump, the monomer diffusion, and the zero shear relaxation function, we confirm that the effective kinetic constants found are indeed the relevant parameters when macroscopic relaxation is coupled to the kinetics of micelles.<p>For the non-equilibrium situation, we study the coupled effects of the shear flow and the scission-recombination kinetics, on the structural and rheological properties of this micellar system. Our study is performed in semi-dilute and dynamically unentangled regime conditions. The explored parameter omega range is chosen in order for the life time of the average size chain to remain shorter than its intrinsic (Rouse) longest relaxation time. Central to our analysis is the concept of dynamical unit of size Lambda, the chain fragment for which the life time tau_Lambda and the Rouse time are equal. Shear thinning, chain gyration tensor anisotropy, chain orientation and bond stretching are found to depend upon the reduced shear rate Beta_Lambda=gamma dot*tau_Lambda while the average micelle size is found to decrease with increasing shear rate, independently of the height of the barrier of the scission-recombination process. / Doctorat en sciences, Spécialisation physique / info:eu-repo/semantics/nonPublished