In the wetter climates associated with the coastal forests of northwestern North America, coarse woody debris (CWD) accumulations in the form of snags, downed boles, and large branches can be large in natural forest ecosystems. Seedlings often regenerate on stumps and downed logs in the understory of old-growth coastal forests. The question remains though, whether CWD is a necessary component for seedling survival and growth in forests managed for commodity production. This study addresses one concern of forest managers: is there an immediate nutritional or moisture supply advantage conferred by CWD for the survival and growth of seedlings in the coastal climate of British Columbia? We compared survival and growth of seedlings planted in decaying wood compared to non-woody humus forms and mineral soil under heavy shade and full light conditions. Low light environments are of particular interest since reports of the strong association between CWD and regeneration has primarily referred to understory seedlings and saplings in old-growth forests.

In the wetter climates associated with the coastal forests of the Pacific Northwest, coarse woody debris (CWD) accumulations in the form of snags, downed boles, and large branches can be large in natural forest ecosystems. Although maintaining organic matter for sustainable site productivity is not in dispute, the importance of CWD as a source of soil organic matter is questionable. Forest managers attempting to optimize timber production need to know how CWD affects short-term forest tree growth and productivity. This study addresses the question of the immediate value of CWD for growth of mature (90 year old) western hemlock (Hw). Because of practical difficulty with mature trees growing in different substrates, we utilized fine root distribution or proliferation, as an indicator of important substrates.

Natural coarse textured soils comprise a significant portion (approximately 20%) of the area to be mined at Suncor, Syncrude (aurora mine), Albian/Shell, and CNRL mines in the Alberta’s oil sands (Macyk, 2006). Although similar in soil textural classifications, the undisturbed areas support a range of ecosite types which exhibit different moisture regimes, suggesting that there are natural mechanisms controlling the plant available water sufficient for forest development. The global objective of this study was to evaluate the potential for textural variability to enhance water storage in coarse textured soil. The observations of the infiltration and drainage behaviour of natural and reclaimed coarse-texture soils in this study have demonstrated that this potential exists and can be applied in reclamation design to achieve the ranges of soil water storage needed to establish different ecosites. Field based infiltration and drainage testing, pit excavation and sampling have been completed on 14 sites (7 natural and 7 reclaimed). Bulk saturated hydraulic conductivity and field capacity were estimated for each of the 14 sites based on the field test results. The observed transient water dynamics give an indication of the effect of layering on these material properties. Laboratory analysis of water content (650 samples), particle size (650 samples), water retention (35 samples), organic carbon (100 samples) as well as calibration of field instrumentation were completed on a large number of samples (approximate values shown in brackets above) across all sites. The laboratory analysis was used to characterize textural variability (mean and standard deviation of the particle diameter) for the layered sites and estimate the soil water retention curve (SWRC) relationships for the range of soil textures encountered at the study sites. Pedotransfer functions (PTFs) were used to investigate if there were significant differences in the residual sum of squares between estimated and measured SWRCs. The measured organic carbon was used to aid in estimating permanent wilting point (WP) used in the calculation of the available water holding capacity (AWHC) of all profiles. An investigation into the calibration of the moisture capacitance probe (MCP) was undertaken as part of a comparison of the measured and simulated volumetric water content (VWC) profiles. Water storage at the cessation of drainage was related to the soil texture and textural variability as measured in the laboratory. Sites with more textural variability generally stored more water for plant use. There appeared to be a limit to what can be considered ‘useful’ textural variability. If adjacent soil layers had too extreme a contrast in texture and therefore hydraulic conductivity, unstable/preferential flow (i.e. bypassing of some of the water and nutrients from plant roots) occurred. The total porosity calculated from field samples was often higher than the maximum measured VWC in each layer which may be indicative of one or more factors that resulted in less than full saturation being attained within the targeted 1 m depth of saturation during the test. Some of these factors include: errors in sampling leading to an overestimate of total porosity; lateral flow along textural interfaces; air entrapment within the rapidly advancing wetting front; unstable/preferential flow as a result of the high contrast in hydraulic conductivity (fine over coarse) between adjacent layers (i.e. Ks Ratio >20) or where tests were conducted on slopes (i.e. funnel flow). This latter case was common at the reclaimed sites. A modelling study of one uniform (SV10) and one layered (NLFH1) natural site was conducted. The models were built by incorporating soil properties of the layers in the various soil profiles as estimated from field and/or laboratory testing. This study offers a comparison between various PTFs and their ability to capture the soil-water storage/dynamics during infiltration and drainage testing. The Arya PTF gave a better estimation of the laboratory measured SWRCs. However, when modeling the measured infiltration and drainage testing for the relatively uniform site SV10, the Arya PTF and Modified Kovacs (MK) PTF performed similarly. The Arya PTF performing slightly better for the infiltration phase and the MK PTF performing slightly better for the drainage phase. Both PTFs gave a reasonable estimation of water storage but the MK PTF gave a better estimation of the water storage with time as compared to the Arya PTF. For the highly layered site NLFH1, neither model performed well. The Arya PTF gave a substantially better estimation of the infiltration phase and gave the better estimation of the magnitude of water storage with time, the MK PTF performed marginally better for the drainage phase and gave a better estimation of the shape of the water storage with time. Generally, the study showed that the replication of the profile water storage requirements for the layered natural ecosites (‘b’ and ‘d’ ecosites) has been achieved and can be achieved by layering (or even mixing) available coarse textured reclamation materials. This study has indicated that replicating the highly uniform ecosites (‘a’ ecosites) is where the bigger challenge lies in reclamation. Reclaiming with a diversity of target ecosites is essential to achieving the pre-disturbance land capability standard that the mine operators are bound by. The temptation may exist to simply condone reclamation that has met or exceeded the pre-exisiting land capability. However, problems with ground water recharge and regional water distribution are likely to arise if large areas of lower functioning ecosites are replaced with higher functioning ecosites.

LTA-type zeolites with narrow window apertures coinciding with the approximate size of small gaseous molecules such as CO2 and N2 are interesting candidates for adsorbents with swing adsorption technologies due to their molecular sieving capabilities and otherwise attractive properties. These sieving capabilities are dependent on the energy barriers of diffusion between the zeolite pores, which can be fine-tuned by altering the framework composition. An ab initio level of theory is necessary to accurately describe specific gas-zeolite interaction and diffusion properties, while it is desirable to predict the macroscopic scale diffusion for industrial applications. Hence, a multiscale modeling approach is necessary to describe the molecular sieving phenomena exhaustively. In this thesis, we use several different modeling methods on different length and time scales to describe the diffusion driven uptake and separation of CO2 and N2 in Zeolite NaKA. A combination of classical force field based modeling methods are used to show the importance of taking into account both thermodynamic, as well as, kinetic effects when modeling gas uptake in narrow pore zeolites where the gas diffusion is to some extent hindered. For a more detailed investigation of the gas molecules’ pore-to-pore dynamics in the material, we present a procedure to compute the free energy barriers of diffusion using spatially constrained ab initio Molecular Dynamics. With this procedure, we seek to identify diffusion rate determining local properties of the Zeolite NaKA pores, including the Na+-to-K+ exchange at different ion sites and the presence of additional CO2 molecules in the pores. This energy barrier information is then used as input for the Kinetic Monte Carlo method, allowing us to simulate and compare these and other effects on the diffusion driven uptake using a realistic powder particle model on macroscopic timescales. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004. / Thesis documentation sheet inserted. Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix .

Electronic coarse graining is a technique improving the predictive power of molecular dynamics simulations by representing electrons via a quantum harmonic oscillator. This construction, known as a Quantum Drude Oscillator, provides all molecular long-range responses by uniting many-body dispersion, polarisation and cross interactions to all orders. To demonstrate the predictive power of electronic coarse graining and provide insights into the physics of water, a molecular model of water based on Quantum Drude Oscillators is developed. The model is parametrised to the properties of an isolated molecule and a single cut through the dimer energy surface. Such a parametrisation makes the condensed phase properties of the model a prediction rather than a fitting target. These properties are studied in four environments via two-temperature adiabatic path integral molecular dynamics: a proton ordered ice, the liquid{vapour interface, supercritical and supercooled water. In all these environments, the model predicts a condensed phase in excellent agreement with experiment, showing impressive transferability. It predicts correct densities and pressures in liquid water from 220 K to 647 K, and a correct temperature of maximum density. Furthermore, it predicts the surface tension, the liquid-vapour critical point, density of ice II, and radial distribution functions across all conditions studied. The model also provides insight into the relationship between the molecular structure of water and its condensed phase properties. An asymmetry between donor and acceptor hydrogen bonds is identified as the molecular scale mechanism responsible for the surface orientation of water molecules. The dipole moment is identified as a molecular scale signature of liquid-like and gas-like regions in supercritical water. Finally, a link between the coordination number and the anomalous thermal expansion of the second coordination shell is also presented.

No description available.

Multifractals have during the past 20 − 25 years been the focus of enormous attention in the mathematical literature. Loosely speaking there are two main ingredients in multifractal analysis: the multifractal spectra and the Renyi dimensions. One of the main goals in multifractal analysis is to understand these two ingredients and their relationship with each other. Motivated by the powerful techniques provided by the use of the Artin-Mazur zeta-functions in number theory and the use of the Ruelle zeta-functions in dynamical systems, Lapidus and collaborators (see books by Lapidus & van Frankenhuysen [32, 33] and the references therein) have introduced and pioneered use of zeta-functions in fractal geometry. Inspired by this development, within the past 7−8 years several authors have paralleled this development by introducing zeta-functions into multifractal geometry. Our result inspired by this work will be given in section 2.2.2. There we introduce geometric multifractal zeta-functions providing precise information of very general classes of multifractal spectra, including, for example, the multifractal spectra of self-conformal measures and the multifractal spectra of ergodic Birkhoff averages of continuous functions. Results in that section are based on paper [37]. Dynamical zeta-functions have been introduced and developed by Ruelle [63, 64] and others, (see, for example, the surveys and books [3, 54, 55] and the references therein). It has been a major challenge to introduce and develop a natural and meaningful theory of dynamical multifractal zeta-functions paralleling existing theory of dynamical zeta functions. In particular, in the setting of self-conformal constructions, Olsen [49] introduced a family of dynamical multifractal zeta-functions designed to provide precise information of very general classes of multifractal spectra, including, for example, the multifractal spectra of self-conformal measures and the multifractal spectra of ergodic Birkhoff averages of continuous functions. However, recently it has been recognised that while self-conformal constructions provide a useful and important framework for studying fractal and multifractal geometry, the more general notion of graph-directed self-conformal constructions provide a substantially more flexible and useful framework, see, for example, [36] for an elaboration of this. In recognition of this viewpoint, in section 2.3.11 we provide main definitions of the multifractal pressure and the multifractal dynamical zeta-functions and we state our main results. This section is based on paper [38]. Setting we are working unifies various different multifractal spectra including fine multifractal spectra of self-conformal measures or Birkhoff averages of continuous function. It was introduced by Olsen in [43]. In section 2.1 we propose answer to problem of defining Renyi spectra in more general settings and provide slight improvement of result regrading multifractal spectra in the case of Subshift of finite type.

L’estimation des déformations différées, en particulier dans le cas des Béton à Hautes Performances (BHP) destinés aux ouvrages d’art, est primordiale pour prédire les flèches, les redistributions des contraintes dans les structures hyperstatiques et les pertes de précontrainte dans des éléments en béton précontraint. L’expérience montre néanmoins une dispersion certaine des valeurs de déformations instantanées et différées mesurées et des écarts non négligeables avec les valeurs calculées selon les règlements de dimensionnement.L’objectif de ce travail de thèse est de s’intéresser à un paramètre non pris en compte dans les règlements qui pourrait être à l’origine des imprécisions de leurs prédictions : le gravillon. Le programme expérimental s’articulera autour d’une étude comparative des comportements mécaniques instantanés et différés sans charge, retrait, et sous charge, fluage, de six BHP de même formulation de base (rapport E/L, volume de pâte), se différenciant principalement par le type de gravillon. A partir de cette base de données complétée par des analyses mécaniques et physico-chimiques sur les granulats, des paramètres influents liés au type de gravillon incorporé ont été détectés. Des comparaisons avec les estimations des modèles actuels tels que l'Eurocode 2 ont également été réalisées et ont montré des différences notables avec les valeurs expérimentales.Des analyses microstructurales ont été menées afin d'identifier l'état de la microstructure et du réseau poreux des matériaux, plus particulièrement à l'interface pâte-granulat (Interfacial Transition Zone ITZ). L'étude de l’ensemble des résultats a permis d’établir des corrélations entre le comportement mécanique et les analyses microstructurales. Une synthèse des données récoltées durant ce travail de recherche montre que le gravillon a une influence non négligeable sur les comportements mécaniques instantané et différé à travers différents paramètres de degré d'influence variable / The prediction of the time-dependent deformations, particularly in the case of high performance concrete (HPC) envisioned for bridges is essential for predicting the deflections, the stress distribution in statically indeterminate structures and the loss of pre-stressing force in elements of pre-stressed concrete. However, the experience shows a certain dispersion of values of instantaneous and delayed deformations measured and some significant differences with the values calculated using the building codes.The objective of the present thesis work focuses on the coarse aggregate parameter which is not taken into account in building codes, which could causes the inaccuracies of their predictions. The experimental program includes a comparative study of the mechanical behaviours (instantaneous and delayed), shrinkage, creep, of six HPC with the same basic formulation (water cement ratio, volume of paste), differing principally in the type of coarse aggregate. From this database and thanks to the mechanical and physicochemical analyses of the aggregates, some influent parameters related to the type of the coarse aggregate were detected. The comparisons with estimations of standard models such as Eurocode 2 were also performed and showed significant differences with the experimental values.Micro-structural analyses were carried out in order to identify the state of the microstructure and the porosity of materials, more particularly at the interface between the cement paste and the coarse aggregate (Interfacial Transition Zones ITZ). The study of the results made it possible to establish correlations between the mechanical behaviour and the micro-structural analyses. A synthesis of the data collected during this research work shows that the coarse aggregate has a considerable influence on the mechanical behaviours (instantaneous and delayed) through various parameters from variable degree of influence

Master of Science / Department of Civil Engineering / Stacey Kulesza / In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 (“Standard Method of Test for Determining Minimum Laboratory Soil Resistivity”). AASHTO T 288-12 is designed to test a soil sample’s electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate. In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material’s bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.