Logical foundations of nonmonotonic reasoning

In this paper we shall review the main appraches to nonmonotonic reasoning which we classify from the perspective of their underlying logical settings as classical, intuitionistic, three-valued/partial models, and conditional. We shall be placing special emphasis on some of the prominent approaches. We shall also give hints on potential future directions and emphasize that more theoretical work is still needed before a move to application is made.     

ViStA: a visualization system for exploring Arabic text

Text visualization has become a significant tool that facilitates knowledge discovery and insightful presentation of large amounts of data. This paper presents a visualization system for exploring Arabic text called ViStA. We report about the design, the implementation and some of the experiments we conducted on the system. The development of such tools assists Arabic language analysts to effectively explore, understand, and discover interesting knowledge hidden in text data. We used statistical techniques from the field of Information Retrieval to identify the relevant documents coupled with sophisticated natural language processing (NLP) tools to process the text. For text visualization, the system used a hybrid approach combining latent semantic indexing for feature selection and multidimensional scaling for dimensionality reduction. Initial results confirm the viability of using this approach to tackle the problem of Arabic text visualization and other Arabic NLP applications.     

Retardation of Dredged Material Leachate in Foundation Soils

Contaminated dredged material is often placed in confined disposal facilities (CDFs) designed and managed to control environmental impacts of the disposed sediment. This note presents equations for use in a screening procedure to evaluate the impact of a CDF on groundwater. The hydrologic evaluation of leachate production and quality model was used to simulate leachate production and transport through the foundation considering a range of foundation soil characteristics and contaminant properties. The model results were used to develop predictive equations of contaminant attenuation and travel time in the foundation soils. When used with equations to predict dispersion in the aquifer, contaminant exposures at receptor locations can be predicted, which is essential in leachate screening applications. The approach does not consider degradation or permanent sequestration of contaminants. Therefore, the procedure is conservative in that it may overestimate actual leachate concentrations and underestimate actual travel times.     

Stochastic Model for Landfill Gas Transport and Energy Recovery

Predicting the amount of landfill gas (LFG) that will be recovered at a sanitary landfill is generally associated with a high level of uncertainty, which is primarily due to the uncertainty in the definition of the parameters that control the LFG generation rate and LFG transport. To quantify these uncertainties, a three-dimensional stochastic model for the generation and transport of LFG is proposed. Using Monte Carlo simulations, multiple realizations of key input parameters are generated. For each realization, LFG transport is simulated and then used to evaluate probabilistically the rates and efficiency of energy recovery. For demonstration, the stochastic model is applied to the Kemerburgaz landfill in Istanbul, Turkey. Uncertainty in the definition of three key parameters, namely: the LFG production rate, the waste gas permeability and the soil cover gas permeability were accounted for. Modeling results suggest that the collection system is sufficient to capture most of the generated gas, but that uncertainty in the factors controlling LFG production is the main source of uncertainty in the amount of energy that will be recovered.     

Characterizing cerebral oxygen metabolism employing oxygen-17 MRI/MRS at high fields

This article provides a comprehensive overview of oxygen (¹⁷O) magnetic resonance spectroscopy and imaging, including the advantages and challenges offered by the different methods developed thus far. The physiological role and relevance of oxygen, and its participation in aerobic metabolism, are addressed to emphasize the importance of the investigations and the efforts related to these developments. Furthermore, a number of methods employed in the determination of the cerebral metabolic rate of oxygen in neural cells will be presented, focusing primarily on methodologies enabling absolute quantification.     

Boron nitride-reinforced polysilazane-derived ceramic composites via direct-ink writing

In this study we investigate the use of hexagonal boron nitride (hBN) as a rheology modifier in polysilazane resin to enable direct-ink writing (DIW) of polysilazane-derived boron nitride-reinforced ceramic composites. hBN is shown to effectively modify the flow properties of the resin by imparting strong shear thinning and yield stress behavior, and to reduce the mass loss and shrinkage associated with the polymer-to-ceramic conversion process, when compared with unfilled polysilazane resin. DIW inks are formulated with 40 vol.% hBN and used print flexural specimens and complex structures with high resolution. Mechanical properties of the resulting polymer-derived ceramic composites were evaluated by 3-pt. flexure and Vickers microhardness. The printed composites exhibit flexural strength of 56.4 MPa and microhardness of 111.4 HV2.     

Considerations for the development of radiation resistant devices and VLSI circuits

The impact of radiation on Very Large Scale Integration (VLSI) silicon technology is discussed with a focus on Complimentary Metal-Oxide Semiconductor (CMOS). Effects of total dose, transient radiation, single event phenomena, and neutron fluence on devices and circuits are presented. General approaches to mitigating radiation effects are put forth. With proper considerations, VLSI CMOS can be enhanced to achieve several orders-of-magnitude increase in radiation tolerance.     

Answers to modal and hypothetical questions in knowledge base systems

This paper describes a computational model which is geared towards providing helpful answers to modal and hypothetical questions in knowledge base systems (KBSs). The model is an essential component of a more complete model which aims at giving helpful answers to questions presented in a natural language. The overall work touches on formal semantic theories on modality and question answering (which have been mainly addressed by linguists and semanticists), intensionality, partiality and belief revision. In this paper, we shall mainly be concerned with the question of partiality where we present a three-valued logic, to which we shall refer as K-T, for reasoning with incomplete information and a proof method for the logic. Along the way, we shall lightly touch on other issues such as answerhood, modality, context and helpfulness.     

A Formalism for Representing and Reasoning with Temporal Information,Event and Change

In this paper we present a general formalism for representing and reasoning with temporal information, event and change. The temporal framework is a theory of time that takes both points and interval as temporal primitives and where the base logic is that of Kleene’s three-valued logic. Thus, we can avoid the Divided Instant Problem (DIP). We present a three-valued based Temporal First-Order Nonmonotonic Logic (TFONL) that employs an explicit representation of time and events. We may embody default logic into TFONL, which takes into consideration the frame, qualification and ramification problems.     

Psychological dynamics of intractable ethnonational conflicts: The Israeli–Palestinian case.

In this article, the authors use the Israeli–Palestinian conflict as an example of ostensibly intractable ethnonational conflict and examine the psychological dynamics that contribute to its intractability. They review the unique characteristics of this conflict and the clash of narratives. They argue that some ethnonational conflicts have characteristics that increase their resistance to change and that societies in such conflicts form societal beliefs that, on the one hand, help them cope with the stressful conditions of the conflicts but, on the other hand, perpetuate the conflicts. Finally, they discuss some social psychological contributions to changing societal beliefs as a way of intervening in such conflicts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)