Integrating Knowledge-Based and Case-Based Reasoning

There has been substantial recent interest in integrating knowledge based reasoning (KBR) and case-based reasoning (CBR) within a single system due to the potential synergisms that could result. Here we describe our recent work investigating the feasibility of a combined KBR-CBR application-independent system for interpreting multi-episode stories/narratives, illustrating it with an application in the domain of interpreting urban warfare stories. A genetic algorithm is used to derive weights for selection of the most relevant past cases. In this setting, we examine the relative value of using input features of a problem for case selection versus using features inferred via KBR, versus both. We find that using both types of features is best (compared to human selection), but that input features are most helpful and inferred features are of marginal value. This finding supports the idea that KBR and CBR provide complimentary rather than redundant information, and hence that their combination in a single system is likely to be useful

Structure Property Relationships and Cationic Doping in [Ca24Al28O64]4+ Framework: A Review

Ca12Al14O33 (C12A7, 12CaO·7Al2O3, or [ Ca 12 Al 14 O 32 ] 2 + : O 2 − ) is a material with a clathrate cage framework, positively charged and stabilized by anions occluded within 17% of the cages. The occluded anion is modular and can be elemental, polyatomic, and electronic in nature. This review focuses on the electride C12A7 ( [ Ca 24 Al 28 O 64 ] 4 + : ( 4 * ∂ ) e − ( 2 − ∂ ) O 2 − ), where O2− anions are replaced with electrons, and compliments previous structural and electronic property reviews to illuminate the structure–property relationships. Electride formation is updated with new findings in carbonaceous reduction methods. Most importantly, an extensive compilation of cationic doped C12A7 isostructural compounds is presented as motivation to study doped C12A7 electrides. Cationic dopants have profound impacts on the electronic properties due to changes in the density of states, localized electron behavior, and structural distortions

Formation Studies of Ca12Al14O33

Ca12Al14O33, also known as mayenite or C12A7, is a functional material with many applications; most uniquely is the ability to form a conductive oxide. The performance of the material is altered with the addition of dopants, both cationic and anionic, as well as with the control of sample microstructure. Obtaining further performance increases requires a robust, rapid, and low temperature synthesis method for doped C12A7, an understanding of the kinetics of formation to control microstructure, and development of direct electronic material synthesis method.Conventional synthesis of ceramic materials follows the solid-state synthesis method which homogenizes a heterogenous mixture of reactants with high temperatures and long process times. Sol-gel synthesis methods utilizing atomically homogenous reactants lead to a decrease in process time and temperature yielding a controllable microstructure. A polymer assisted sol-gel method is developed which overcomes chemical constraints of the amorphous citrate sol-gel method and allows for robust, rapid, and low-temperature synthesis for large cationic systems.Elucidation of the kinetics behind12A7 synthesis and formation traditionally adopts a thermodynamic approach that characterizes the end-point and provides little understanding of the journey to that thermodynamic equilibrium. In-situ X-ray diffraction is employed to study the kinetics of formation as a function of reactant homogeneity and atmosphere to elucidate the kinetic pathways in real time. The polymer-assisted reactants lead to a 30% decrease in formation temperature, order of magnitude reduction in formation time, and two orders of magnitude reduction in grain size.The current process to form electrically conducting C12A7 requires the synthesis, consolidation, and then reduction of oxy-C12A7. This consists of multiple long duration high temperature processing steps prohibiting microstructural control. Herein a direct electride synthesis technique is developed and a theory behind the kinetics of formation is presented. Consolidated semi-conducting C12A7 is directly synthesized in under 12 h with room for process refinement to further reduce this time.The refinement of a robust homogenous reactant synthesis method, elucidation of the kinetic pathways of formation, and the development of a direct electride synthesis method allows for the formation of doped C12A7 electronic materials with a controlled microstructure leading to an increase in performance of a functional material with nearly endless applications

In-Situ Kinetic Investigation of Calcium Aluminate Formation

Rapid in-situ non-ambient X-ray diffraction represents a powerful tool for characterizing the evolution of crystalline materials in real time. The calcium aluminate system and formation of Ca12Al14O33 (C12A7) is particularly sensitive to processing conditions. This report characterizes the kinetic pathways to thermodynamic equilibrium as a function of atmosphere (ambient, dry, and vacuum) and reactant heterogeneity (as-received, milled, and sol-gel reactants). When reactants are heterogenous (as-received and milled), intermediary phases of Ca3Al2O6 (C3A) and CaAl2O4 (CA) are observed as the route to C12A7 formation and Ca5Al6O14 (C5A3) is only observed as a decomposition product of C12A7. When reactants are heterogenous, C12A7 is only thermodynamically favorable under ambient conditions due to the stability provided by hydration. When reactants are homogenous (sol-gel), direct crystallization of C12A7 from an amorphous precursor is observed at low temperature regardless of atmosphere defining C12A7 as the kinetic equilibrium. These findings accurately define the heterogenous formation pathways and report for the first time the formation of C12A7 under a carbon-free vacuum environment

From System Requirements to System Architecture

For the last decade, a large body of research in software engineering has developed methods, notations, and tools for rigorously specifying architectures and for performing architecture-level analysis. Yet the key issue of constructing a system architecture that meets a given set of requirements remains largely open. In this paper, we propose a systematic, rigorous connection between requirements and the architecture that implements them