PGSW-OS: a novel approach for resource management in a semantic web operating system based on a P2P grid architecture

A web operating system is an operating system that users can access from any hardware at any location. A peer-to-peer (P2P) grid uses P2P communication for resource management and communication between nodes in a grid and manages resources locally in each cluster, and this provides a proper architecture for a web operating system. Use of semantic technology in web operating systems is an emerging field that improves the management and discovery of resources and services. In this paper, we propose PGSW-OS (P2P grid semantic Web OS), a model based on a P2P grid architecture and semantic technology to improve resource management in a web operating system through resource discovery with the aid of semantic features. Our approach integrates distributed hash tables (DHTs) and semantic overlay networks to enable semantic-based resource management by advertising resources in the DHT based upon their annotations to enable semantic-based resource matchmaking. Our model includes ontologies and virtual organizations. Our technique decreases the computational complexity of searching in a web operating system environment. We perform a simulation study using the Gridsim simulator, and our experiments show that our model provides enhanced utilization of resources, better search expressiveness, scalability, and precision.     

Developments in denture teeth to prevent softening by food solvents

The effect of various food-simulating solvents on the hardness of denture teeth after varying storage times, using a Martens hardness test was determined. Martens hardness (HM) was assessed at baseline and during storage up to 1 month in distilled water (DW), peppermint oil (PO), heptane (HT) and 75% ethanol (ET) for four commercially-available denture teeth; Vivodent (VIV), Double-cross-linked Postaris (DCL), Orthosit (ORT), Candulor porcelain (POR) and two polymer based experimental denture teeth: Experimental 1 (EXP1); a hybrid nanocomposite with two different sized silanated filler particles and Experimental 2 (EXP2); containing an organic copolymer based upon urethanedimethacrylate and polymethyl methacrylate. Hardness [mean (sd)] at baseline was: VIV 142 (1), DCL 142 (1), ORT 209 (9), POR 2926 (101), EXP1 285 (11), and EXP2 146 (12). One-way ANOVA using Tukey’s test on polymer-based materials showed that the hardness values of ORT and EXP1 were significantly higher than those of VIV, DCL and EXP2 (P < 0.05). Moreover, EXP1 had a significantly higher hardness value than ORT (P < 0.05). Except for EXP1, all polymer based materials showed a significant drop in hardness after storage in ET (P < 0.05). Specimens stored in water, heptane and peppermint oil showed minor fluctuations in hardness, which were not statistically significant.     

Residential demand for energy commodities : A household production function approach

This paper formulates a demand model for energy commodities using a household production function approach. The model is stated in a utility maximization framework where utility is assumed to be a function of two composite commodities directly yielding utility. Electricity and natural gas are used as inputs along with a capital stock to produce one of the utility-yielding commodities. The other utility-yielding commodity is assumed to be produced with two non-energy goods and capital stock which are purchased on the market. The Kuhn-Tucker conditions are then used to characterize the optimal time paths for input purchases and investments by the household.