Utilizing Semantic Knowledge for Access Control in Pervasive and Ubiquitous Systems

Controlling access in pervasive environments is crucial and a significant challenge because users and devices can connect from anywhere which results in users and resources becoming available at any point of time and location depending on the situation. Access control policies for this type of environment are required to conform to high-level business notions. In pervasive environments, these high-level notions refer to contexts of the situation which can change unpredictably and must be interpreted semantically to maintain proper access control. Therefore, it is necessary to have a formal representation that represents semantics of the contexts, reflects the change of the situation, and can be shared and understood by a policy system. This paper addresses these issues by introducing a context management system that uses a semantic web approach as an underlying mechanism to model and represent semantics of the contexts. The system stores current contexts in a semantic knowledge base which is used by a semantic access control system in order to form access control policies and evaluate policies at run time. The approach is validated through a proof of concept implementation that includes performance results of the context management system as it responds to a change of the situation.     

Discrete Convolution in Power System Reliability

This paper describes a general method for convolving discrete distributions using Fast Fourier Transforms. It can be used in evaluating reliability of any system involving discrete or discretised convolution. It has been used in power system studies to deduce capacity-outage probability tables and to solve probabilistic load flows. These studies have shown it to be much less time-consuming and more efficient than the conventional direct methods. The method is used in the paper to evaluate the loss of load probability of a generating system in order to demonstrate the method's application and inherent merits.     

An investigation of the microstructure and mechanical properties of high density polyethylene spherulites

Scanning transmission electron microscopy and related techniques have been used to characterize the micromorphologies of high-density polyethylene spherulites produced under different crystallization conditions. The experimental techniques used in the investigation are summarized, as are some relationhips between spherulite morphology, crystallization conditions and mechanical properties. A preliminary model for the micromorphology of banded polyethylene spherulites is proposed.     

Atmospheric-pressure dielectric barrier discharge generation by a full-bridge flying capacitor multilevel inverter

A new configuration of a resonant full-bridge flying capacitor multicell inverter has been designed and constructed with the aim of achieving an extended output voltage frequency range with low harmonic distortion and reduced semiconductor commutation losses. This configuration was tested as a power supply for two different coaxial dielectric barrier discharge reactors, one of them employed for electric characterization and the other one for inorganic compound elimination in an aqueous solution. Two different gas mixtures, 90% Ar–10% O_2 and80% Ar–20% O_2, were individually supplied during the experiments; the results showed a highefficiency removal of meta-cresol(m-cresol) to the order of 98%, which was obtained by adding more oxygen to the plasma gas mixture.     

Imagery and synchronic thinking.

Argues that imagery involves synchronously organized informational structures that contribute to the richness of content, flexibility, and speed of thinking. By contrast, verbal processes are characterized by a higher degree of sequential constraint, which limits memory content and flexibility but contributes logical direction to thinking. Specific experimental evidence is presented on the implications of these views in regard to the encoding, storage, and retrieval of organized cognitive information. (11/2 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tailoring smoking withdrawal procedures to personality and motivational differences.

Used concentrated cigarette smoke as an aversive agent in the treatment of 89 habitual cigarette smokers. A factorial design assessed the incremental efficacy of 3 procedures, hypothesized to increase treatment durability, as a function of client characteristics. The 1st, treatment focus, contrasted procedures considered optimal for internal vs external locus of control clients (measured with Rotter's Internal-External Control Scale). The 2nd, punishment, assessed an instruction to punish postclinic smoking with stimulus satiation conditions. The 3rd, timing of attitude change, presented an attitude change manipulation either before or after behavior change. The Eysenck Personality Inventory and C. S. Keutzer's effective cognitive dissonance measure were also administered. Changes in smoking behavior were monitored over a 6-mo period. 2 of the 3 treatment factors, treatment focus and timing of attitude change, interacted significantly with client characteristics in determining treatment outcome. Findings support the principle of tailoring therapeutic procedures to individual differences. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The emerging field of the sociology of psychological knowledge.

Considers the social context in which professional academicians practice psychology. The ties of psychological knowledge to the infrastructure of society are noted, and comparisons with the sociology of knowledge are made. The underlying social biases of 5 areas within psychology (differential, humanistic, developmental, behavioristic, and social) are reviewed. Recent articles from the American Psychologist are sampled to indicate the growing awareness by the profession of the social base of its activities. (86 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic mechanical properties of polystyrene-polydimethylsiloxane blends

It was found that commercial silicone grease incorporated accidentally into polystyrene bars yields a major dynamic mechanical loss peak at ca. ?128°C. This finding was followed up with a study of various polydimethylsiloxanes and silicone rubber, in which up to three peaks were found. In order of increasing temperature (at 1 Hz) these are the glass transition (T_g; ca. ?128°C), crystallization (T_c; ca. ?110°C) and melting peaks (T_m; ca. ?50°C). Hydrocarbon-based greases were also investigated. The results indicate that the methods employed may be of use for the investigation of the dynamic mechanical properties of small amounts of material of varying particle sizes, such as powders of cross-linked polymers, that need not be compatible with, or soluble in, the host matrix. The sensitivity of the method is such at a 1 percent by weight contamination of silicone grease in polystyrene gives a loss tangent peak of at least 0.002 above background, and emphasizes the necessary care to be taken during sample preparation to exclude unwanted substances.     

Ignition characteristics of chars made in the G R & D coal-gasification and coal-to-liquids processes

Chars are obtained as by-products in the coal-gasification and coal-to-liquids processes currently in the pilot-plant stage at Garrett Research & Development Company, Inc. Ignition tests have been carried out on these chars using an ignitability test, i.e. dispersing the chars in oxygen and igniting the mixture in a hot tube. DTA—TGA determinations have also been used to study the static reactions of the chars in air. Both types of char, under roughly simulated pulverized-fuel-firing conditions probably with a significantly lower heating rate, ignited readily at temperatures equal to or lower than those required to ignite the parent coals. Partial oxidation of the char raised the ignition temperature. The heats of combustion of the chars are slightly higher than those of the parent coals and approach that of petroleum coke; the sulphur content per unit of heating value is slightly lower. They are porous materials with a particle-size distribution suitable for use as pulverized fuel. Enough volatile matter remains to give a bright flame after ignition.     

An Efficient Algorithm for Deducing the Minimal Cuts and Reliability Indices of a General Network Configuration

The paper describes an efficient algorithm for evaluating the minimal cut sets of any general network. The algorithm is based on Boolean algebra and set theory, and contains many important improvements. The four most important features are 1. only one set of topological input data is required to evaluate the minimal cuts and reliability indices of every output node; 2. a mix of undirectional, bidirectional and multi ended components can be included very simply; 3. any number of input nodes may be specified; 4. a new concept of overall system reliability permits different, large, and complex systems to be compared. The computational efficiency of the algorithm is clearly indicated by the fact that the time required to analyse Example 1 on a CDC7600 was 0.7 sec. The storage required with the appropriate arrays dimensioned for a system having 100 components and up to 125 minimal cut sets per output node is 15 k-words. These times and storage include the overall system reliability analysis.