Volatilization-devolatilization reactions

Experiments that explore chemical and physical aspects of volatilization reactions that require the microgravity and low pressure in or near the projected Space Station are proposed

Fluid Assisted Compaction and Deformation of Reservoir Lithologies

The compaction and diagenesis of sandstones that form reservoirs to hydrocarbons depend on mechanical compaction processes, fluid flow at local and regional scales, and chemical processes of dissolution, precipitation and diffusional solution transport. The compaction and distortional deformation of quartz aggregates exposed to reactive aqueous fluids have been investigated experimentally at varying critical and subcritical stress states and time scales. Pore fluid compositions and reaction rates during deformation have been measured and compared with creep rates. Relative contributions of mechanical and chemical processes to deformation and pore structure evolution have been evaluated using acoustic emission (AE) measurements and scanning electron microscope (SEM) observations. At the subcritical conditions investigated, creep rates and acoustic emission rates fit transient logarithmic creep laws. Based on AE and SEM observations, we conclude that intragranular cracking and grain rearrangement are the dominant strain mechanisms. Specimens show little evidence of stress-enhanced solution transfer. At long times under wet conditions, the dominant strain mechanism gradually shifts from critical cracking at grain contacts with high stress concentrations to fluid-assisted sub-critical cracking

Enhanced deformation of limestone and sandstone in the presence of high pCO2 fluids

International audienceGeological repositories subject to the injection of large amounts of anthropogenic carbon dioxide will undergo chemical and mechanical instabilities for which there are currently little experimental data. This study reports on experiments where low and high pCO2 (8~MPa) aqueous fluids where injected into natural rock samples. The experiments were performed in flow-through triaxial cells, where the vertical and confining stresses, temperature, and pressure and composition of the fluid were separately controlled and monitored. The axial vertical strains of two limestones and one sandstone were continuously measured during separate experiments for several months, with a strain rate resolution of 10^-11 s-1. Fluids exiting the triaxial cells where continuously collected and their compositions analysed. The high pCO2 fluids induced an increase in strain rates of the limestones by up to a factor of 5, compared to the low pCO2 fluids. Injection of high pCO2 fluids into the sandstone resulted in deformation rates one order of magnitude smaller than the limestones. The creep accelerating effect of high pCO2 fluids with respect to the limestones was mainly due to the acidification of the injected fluids, resulting in a significant increase in solubility and reaction kinetics of calcite. Compared to the limestones, the much weaker response of the sandstone was due to the much lower solubility and reactivity of quartz in high pCO2 fluids. In general, all samples showed a positive correlation between fluid flow rate and strain rate. X-ray tomography results revealed significant increases in porosity at the inlet portion of each core; the porosity increases were dependent on the original lithological structure and composition. The overall deformation of the samples is interpreted in terms of simultaneous dissolution reactions in pore spaces and intergranular pressure solution creep

Liberty County Strategic Plan 2016 - 2036

In the fall of 2015, the County of Liberty and Texas Target Communities partnered to create a task force to represent the community. The task force was integral to the planning process, contributing the thoughts, desires, and opinions of community members—as well as their enthusiasm about Liberty’s future. This fourteen-month planning process ended in August 2016. The result of this collaboration is the County of Liberty Strategic Plan, which is the official policy guide for the community’s growth over the next twenty years.Liberty Strategic Plan 2036 provides a guide for the future growth of the county. This document was developed by Texas Target Communities in partnership with the County of Liberty

Hydrothermal processes along mid-ocean ridges: an experimental investigation

An experimental investigation of high-temperature seawater/basalt interactions has been conducted in order to better evaluate the geochemical and economic implications of hydrothermal circulation of seawater in the oceanic crust along active mid-ocean ridges. The results indicate that, as seawater reacts with basalt between 200°C and 500°C at 500-800 bars, the fluid tends to change from an oxygenated, slightly alkaline, Na�, Mg��, SO₄[superscipt =], Cl� solution to a reducing, acidic, Na�, Ca��, Cl� solution with Fe, Mn and Cu concentrations up to 1500, 190 and 0.3 ppm respectively. Silica concentrations in the fluid approach saturation values with respect to quartz at all temperatures; however, Al abundances remain very low (~0.5 ppm). Montmorillonite, nontronite, albite, tremolite-actinolite, chalcopyrite, pyrrhotite and hematite were the dominant alteration products formed. These data imply that large-scale circulation of seawater in the oceanic crust could account for the Al-deficient metalliferous sediments associated with mid-ocean ridges and be important in the genesis of certain Fe-Cu sulfide ore deposits. The process could also affect the geochemical budgets of certain elements and exert substantial control on the steady-state composition of seawater by removing excess Na and Mg and adding Ca, Si and H to the oceans

Robots building together

Thesis: S.M., Massachusetts Institute of Technology, Department of Architecture, 2018.S.M. !c Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science 2018This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged student-submitted from PDF version of thesis.Includes bibliographical references (pages 69-72).Since robots were first invented, robotic assembly has been an important area of research in both academic institutions and industry settings. The standard industry approach to robotic assembly lines utilizes fixed robotic arms and prioritizes speed and precision over customization. With a recent shift towards mobile multi-robot teams, researchers have developed a variety of approaches ranging from planning with uncertainty to swarm robotics. However, existing approaches to robotic assembly are either too rigid, with a deterministic planning approach, or do not take advantage of the opportunities available with multiple robots. If we are to push the boundaries of robotic assembly, then we need to make collaborative robots that can work together, without human intervention, to plan and build large structures that they could not complete alone. By developing teams of robots that can collaboratively work together to plan and build large structures, we could aid in disaster relief, enable construction in remote locations, and support the health of construction workers in hazardous environments. In this thesis, I take a first step towards this vision by developing a simple collaborative task wherein agents learn to work together to move rectilinear blocks. I define robotic collaboration as an emergent process that evolves as multiple agents, simulated or physical, learn to work together to achieve a common goal that they could not achieve in isolation. Rather than taking an explicit planning approach, I employ an area of research in artificial intelligence called reinforcement learning, where agents learn an optimal behavior to achieve a specific goal by receiving rewards or penalties for good and bad behavior, respectively. In this thesis, I defined a framework for training the agents and a goal for them to accomplish. I designed, programmed and built two iterations of physical robots. I developed numerous variations of simulation environments for both single and multiple agents, evaluated reinforcement learning algorithms and selected an approach, and established a method for transferring a trained policy to physical robots.by Kathleen Sofia Hajash.S.M.S.M. !c Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc