Volume change and swelling pressure of expansive clay in the crystalline swelling regime

Title from PDF of title page (University of Missouri--Columbia, viewed on March 2, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dr. William Likos, Thesis Supervisor.Vita.Ph. D. University of Missouri--Columbia 2008.A significant amount of research has been carried out to characterize expansive clay behavior from either microstructural or macrostructural perspectives; however, there exists a current gap in our knowledge about the basic mechanisms that relate one structural level to another. This research investigates: how volume changes occurring on the interlayer scale upscale to volume change and swelling pressure for bulk particle systems, how variables such as void ratio, compaction conditions, particle and pore fabric, confining conditions, initial conditions, pore fluid chemistry, and clay chemistry govern this upscaling process, and what models are available to quantify these effects. Three types of clay were used: Na-smectite, Ca-smectite, and a Ca-exchanged form of the Na-smectite. Results obtained include: SEM imaging of Na and Ca smectite, void ratio vs. compaction pressure, water vapor sorption isotherms, axial deformation vs. relative humidity (RH) for free swell boundary conditions, and swelling pressure vs. RH for constant strain boundary conditions. Effects of initial density, interlayer cation, clay fabric, and stress paths were qualitatively analyzed in light of three conceptual models, and quantified by defining constitutive surfaces for smectite for crystalline swelling. With better knowledge of how microstructural swelling translates to macroscopic behavior, the geotechnical engineering community and industry will be more equipped to approach and resolve the several problems involving expansive clays. .Includes bibliographical reference

Characterization of SdGA, a cold-adapted and salt-tolerant glucoamylase from Saccharophagus degradans

Glucoamylases (GAs) are hydrolytic enzymes also known as amyloglucosidases, glucan 1,4-alphaglucosidases or exo-1,4-1,6 bonds) from the non- -Dglucose. These are typically microbial enzymes present in archaea, bacteria and fungi but absent in animals and plants, and they are classified into the GH15 family of glycoside hydrolases (www.cazy.org).-amylases and pullulanases) occurs in the process of saccharification of partially processed starch or dextrins to obtain glucose. Currently, there is strong interest in finding GAs with a better performance at low temperatures because these enzymes would avoid the heating requirement in some industrial processes such as starch saccharification among others, and, in this way, production costs could be minimized. Saccharophagus degradans is a  gramnegative marine bacterium. It is the most versatile bacterium in terms of the degradation of complex polymers (CP) found to date. It is capable to degrade at least 10 complex polymers such as starch, agar, laminarin, cellulose, pectin, alginate, chitin, fucoidan, pectin, pullulan, and xylan at high rate. The objective of this work is to carry out the structural characterization and functional properties of SdGA, a novel glucoamylase (GA) from S. degradans. The enzyme is composed mainly of a N-terminal GH15_N domainlinked to a C-terminal catalytic domain (CD) found in the GH15 family of glycosylhydrolases with an overall structure similar to other bacterial GAs. The protein was successfully expressed in Escherichia coli cells, purified and its biochemical properties were investigated. SdGA showed maximum activity at 39°C and pH 6.0. The enzyme has high activity in a wide range, from low to mild temperatures, like cold-adapted enzymes. It showed the same maximum activity in the range of 0 1.0 M NaCl like salt-tolerant amylases.By thermal inactivation assays, we determined that SdGA is thermolabile at temperatures above 42°C and we found that glycerol 10% (V/V), acarbose 0.1 mM and NaCl 1 M stabilized the enzyme. Furthermore, we analyze the CD of SdGA, other cold-adapted, psychrophilic and thermostable GAs and we found that SdGA has a larger CD due to various amino acid insertions and a higher content of flexible residues compared to other thermostable GAs. These characteristics of SdGA allow it to be classified as a coldadaptedenzyme but also, a salt-tolerant enzyme. We propose that this novel SdGA, might have potential applications for use in different industrial processes that require an efficient alpha glucosidase activity at low/mild temperatures, such as biofuel production.Fil: Wayllace, Natael Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Hedin, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Busi, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Gomez Casati, Diego Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaTercer Encuentro de Red Argentina de Tecnología Enzimática; Primer Workshop de la Red Argentina de Tecnología EnzimáticaRosarioArgentinaRed Argentina de Tecnología Enzimátic

Autonomous Agents Modelling Other Agents: A Comprehensive Survey and Open Problems

Much research in artificial intelligence is concerned with the development of autonomous agents that can interact effectively with other agents. An important aspect of such agents is the ability to reason about the behaviours of other agents, by constructing models which make predictions about various properties of interest (such as actions, goals, beliefs) of the modelled agents. A variety of modelling approaches now exist which vary widely in their methodology and underlying assumptions, catering to the needs of the different sub-communities within which they were developed and reflecting the different practical uses for which they are intended. The purpose of the present article is to provide a comprehensive survey of the salient modelling methods which can be found in the literature. The article concludes with a discussion of open problems which may form the basis for fruitful future research.Comment: Final manuscript (46 pages), published in Artificial Intelligence Journal. The arXiv version also contains a table of contents after the abstract, but is otherwise identical to the AIJ version. Keywords: autonomous agents, multiagent systems, modelling other agents, opponent modellin

Contribution à l'étude du corps carotidien et de ses tumeurs

(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL

Stochastic Goal Recognition Design

Given an environment and a set of allowed modifications, the task of goal recognition design (GRD) is to select a valid set of modifications that minimizes the maximal number of steps an agent can take before its goal is revealed to an observer. This document presents an extension of GRD to the stochastic domain: the Stochastic Goal Recognition Design (S-GRD). The GRD framework aims to consider: (1) Stochastic agent action outcomes; (2) Partial observability of agent states and actions; and (3) Suboptimal agents. In this abstract we present the progress made towards the final objective as well as a timeline of projected conclusion

Stochastic Goal Recognition Design

Goal Recognition Design (GRD) is the problem of finding the least amount of environment modifications to force an acting agent to reveal its goal as early as possible. Figuring out an agent’s goal by observing its behavior is a problem studied in Psychology, Economics, and Artificial Intelligence, where it is known as goal recognition. Contrary to most common approaches where the focus is on finding faster algorithms to detect the goal, GRD takes an offline approach and focuses on environment design to facilitate goal recognition. This thesis investigates GRD problems when action outcomes are stochastic, which is the case of most physical world interactions. I propose the Stochastic GRD (S-GRD) problem and study its specific characteristics, challenges, and limitations. Under this umbrella, we analyze partially-observable and suboptimal cases and provide a novel way to redesign the environment for partially-observable settings. This thesis presents the problem formulation and novelalgorithms to solve the problem. Additionally, empirical evaluations show that S-GRD helps reduce the complexity of a goal recognition problem in all cases

Stochastic Goal Recognition Design Problems with Suboptimal Agents

Goal Recognition Design (GRD) problems identify the minimum number of environmental modifications aiming to force an interacting agent to reveal its goal as early as possible. Researchers proposed several extensions to the original model, some of them handling stochastic agent action outcomes. While this generalization is useful, it assumes optimal acting agents, which limits its applicability to more realistic scenarios. This paper presents the Suboptimal Stochastic GRD model, where we consider boundedly rational agents that, due to limited resources, might follow a suboptimal policy. Inspired by theories on human behavior asserting that humans are (close to) optimal when making perceptual decisions, we assume the chosen policy has at most m suboptimal actions. Our contribution includes (I) Extending the stochastic goal recognition design framework by supporting suboptimal agents in cases where an observer has either full or partial observability; (ii) Presenting methods to evaluate the ambiguity of the model under these assumptions; and (iii) Evaluating our approach on a range of benchmark applications

Porosity evolution of free and confined bentonites during interlayer hydration

Methods for predicting the volume change and swelling-pressure behavior of expansive clays require detailed understanding of coupled interactions between clay microstructure and macrostructure under hydraulic, thermal, and mechanical loads. In this study a suite of water-vapor sorption experiments was conducted using compacted bentonites hydrated in controlled relative humidity (RH) environments maintained under free and constrained volume-change boundary conditions. Emphasis was placed on examining the influences of compaction and predominant exchange cation on the water uptake, volume change, and swelling pressure response. Densely compacted specimens exhibited greater volume changes under free swelling conditions and greater swelling pressures under fully confined conditions. Water uptake, volume change, and swelling pressure were all more significant for Colorado (Ca2+/Mg2+) bentonite than forWyoming (Na+) bentonite. Plastic yielding, evident as a peak in the relationship between swelling pressure and RH, was more evident and occurred at lower RH for the Colorado bentonite. This observation was interpreted to reflect the limited capacity for interlayer swelling in Ca/Mg bentonites and corresponding structural collapse induced by the onset of water uptake in larger intra-aggregate and inter-aggregate pores. A semi-quantitative model for the evolution of clay microstructure resulting from interlayer hydration was considered to attribute the experimental observations to differences in the efficiency with which transitions in basal spacing translate to bulk volume changes and swelling pressure. Results provide additional insight and experimental evidence to more effectively model the mechanical behavior of compacted bentonites used as buffer or barrier materials in waste repository applications