Semantic Web Constraint Language and its application to an intelligent shopping agent

Semantic Web society was initially focused only on data, but then gradually moved toward knowledge. If a vision of the Semantic Web is to enhance humans' decision-making assisted by machines, a missing but important part is knowledge about constraints on data and concepts represented by ontology. This paper proposes a Semantic Web Constraint Language (SWCL) based on OWL, and shows its effectiveness in representing and solving an internet shopper's decision-making problems by implementing a shopping agent in the Semantic Web environment.     

Application of QFA coupled with CFD analysis to predict the hardness of T6 heat treated Al6061 cylinder

QFA (quench factor analysis) method is widely used to predict the mechanical properties such as hardness and strength according to temperature of quenched material that has to be determined by experimental heat treatment. But, QFA coupled with CFD (computational fluid dynamics) analysis of this study can predict the mechanical properties without the experiment of heat treatment except the experiment to determine the material constants of QFA. First of all, Jominy test and FPS (flexible polyhedron search) are performed to determine the material constants of QFA. The CFD analysis is applied to predict the cooling temperature of Al6061 cylinder cooled by water of 25°C during quenching of solid solution heat treatment. Hardnesses of T6 heat treated Al6061 cylinder is predicted by the QFA coupled with CFD analysis without experiment of heat treatment and then the predicted hardnesses are compared with experimentally measured hardnesses according to positions of cylinder. The predicted hardnesses of cylinder are in good agreement with the measured ones within a maximum error of 8.45%.     

Interprovider differentiated service interconnection management models in the Internet bandwidth commodity markets

Due to the recent evolution of telecommunications infrastructure and the Internet as a commodity market for bandwidth, Internet Service Providers (ISPs) encounter new issues concerned with bandwidth management for the network interconnection. Bandwidth commodity exchange is considered a new B2B (Business-to-Business) electronic commerce application that brings new market opportunities to carriers and service providers for managing their bandwidth resources. This paper develops market-based bandwidth management optimization models for Differentiated Service (DiffServ) QoS (Quality of Service) networks using an implementation of the bandwidth management agent, BMP (Bandwidth Management Point). We use network economic models to formulate an optimization problem for the interconnection and resource allocation policy of the DiffServ network. We formulate and develop those economic models as optimization problems of LP, NLP, MILP and mixed integer nonlinear programming (MINLP), and discuss the pricing mechanisms and available solution approaches for the implementation of the BMP's resource optimization process. Different opportunity costs are estimated based on the results of a network simulation using traffic flow statistics measured from a recent Internet backbone. We then numerically simulate the behavior of backbone network ISPs to optimize their profits for various demand scenarios.     

In Vitro Cytotoxic Evaluation of MgO Nanoparticles and Their Effect on the Expression of ROS Genes

Water-dispersible MgO nanoparticles were tested to investigate their cytotoxic effects on oxidative stress gene expression. In this in vitro study, genes related to reactive oxygen species (ROS), glutathione S-transferase (GST) and catalase, were quantified using real-time polymerase chain reactions (molecular level) and molecular beacon technologies (cellular level). The monodispersed MgO nanoparticles, 20 nm in size, were used to treat human cancer cell lines (liver cancer epithelial cells) at different concentrations (25, 75 and 150 µg/mL) and incubation times (24, 48 and 72 h). Both the genetic and cellular cytotoxic screening methods produced consistent results, showing that GST and catalase ROS gene expression was maximized at 150 µg/mL nanoparticle treatment with 48 h incubation. However, the genotoxic effect of MgO nanoparticles was not significant compared with control experiments, which indicates its significant potential applications in nanomedicine as a diagnostic and therapeutic tool.     

Reduction of Residual Stress and Improvement of Dimensional Accuracy by Uphill Quenching for Al6061 Tube

The purpose of this study is to reduce the residual stress and machining distortion of an Al6061 tube by using uphill quenching. During uphill quenching, solid-solution heat-treated aluminum parts are usually immersed in LN₂ at 77 K (?196 °C), followed by the rapid heating of the parts, to produce a new residual stress that is opposite in nature to the original. The uphill quenching method used in this study employed two types of heating methods: boiling water at 373 K (100 °C) and high-velocity steam at 448 K (175 °C). First, FE-simulation coupled with a CFD analysis was performed to predict the residual stress of the backward hot-extruded Al6061 tube with the following dimensions: Ø200 mm × h200 mm × t10 mm. Experiment of uphill quenching was also conducted to measure the residual stress using the boiling water and high-velocity steam uphill quenching methods. The predicted residual stresses were compared with the experimental results obtained via micro-indentation and saw-cutting tests, and a deviation of about 10.4 pct was found. In addition, the experimental results showed that uphill quenching could relieve up to 91 pct of the residual stress induced by water quenching. Finally, the dimensional accuracy of uphill quenched tubes was evaluated by measuring the roundness after the machining process, which showed that the uphill quenching method could improve the dimensional accuracy of an Al6061 tube by reducing the residual stress.     

Prediction and measurement of relieved residual stress by the cryogenic heat treatment for Al6061 alloy: mechanical properties and microstructure

The purpose of this study is to predict the residual stress resulting from the cryogenic heat treatment (CHT) which affects the mechanical properties and microstructure for Al6061 alloy. The CHT is very effective method to reduce the residual stress by quenching media such as liquid nitrogen, boiling water and steam. In this study, experimental T6 and CHT are carried out to measure the temperature of Al parts and to determine the convective heat transfer coefficient. This coefficient is used to predict the residual stress during FE-simulation. In order to consider the relaxation of residual stress during artificial ageing, the Zener-Wert-Avrami function with elasto-plastic nonlinear analysis is used in this study. The predicted residual stress is compared with the measured one by X-ray diffraction (XRD) and is found to be in good agreement with results of the FE-simulation. Further, after T6 and CHT, the electrical conductivity and hardness of the Al6061 alloy are measured to estimate the mechanical properties and its microstructure such as precipitates is observed by Transmission electron microscopy (TEM). Also, the creation of precipitates during T6 and CHT are verified by XRD with component analysis. It is found that CHT affects the residual stress, mechanical properties, and precipitation of the Al 6061 alloy.     

The effect of SrTiO<Subscript>3</Subscript> addition on the magnetic and microwave properties of yttrium iron garnet

The effect of SrTiO₃ addition on the microstructure and magnetic properties of yttrium iron garnet prepared by a conventional ceramic method was investigated using scanning electron microscopy, X-ray diffractometry, vibrating sample magnetometry, and ferrimagnetic resonance experiments. A YIG specimen sintered at 1693 K with 0.2 mol% SrTiO₃ addition showed above 98% densification of theoretical density without changing in magnetic properties of YIG. A YIG specimen sintered at 1693 K with 0.2 mol% SrTiO₃ showed ferrimagnetic resonance linewidth ΔH of about 80 Oe.     

A myopic mobile sink migration strategy for maximizing lifetime of wireless sensor networks

Network lifetime maximization is challenging particularly for large-scale wireless sensor networks. The sensor nodes near the sink node tend to suffer high energy consumption due to heavy traffic relay operations, becoming vulnerable to energy depletion. The rationale of the sink mobility approach is that as the sink node moves around, such risk of energy depletion at some nodes can be alleviated. In this paper, we first obtain the optimal mobile sink sojourning pattern by solving a linear programming model and then we mathematically analyze why the optimal solution exhibits such sojourning pattern. We use the insights from this analysis to design a simple practical heuristic algorithm for sink mobility, which utilizes only local information. Our heuristic is very different from the existing algorithms which often use the traffic volume as the main decision factor, in that we consider the variance of residual energy of neighboring sensor nodes. The simulation results show that our scheme achieves near-optimal network lifetime even with the relatively low moving speed of the mobile sink.     

Application of an in situ bismuth-coated glassy carbon electrode for electroanalytical determination of Cd (II) and Pb (II) in Korean polished rices

Rapid on-site monitoring of heavy metals in plants is necessary to minimize the exposure of humans to the contaminated food. The potential of using anodic stripping voltammetry (ASV) for simultaneous determination of cadimium (Cd) and lead (Pb) in rice was evaluated. Eight different Korean polished rices were digested using concentrated HNO₃ solution in a microwave oven. The peak currents measured with an in situ bismuth-coated electrode were linearly proportional to Cd and Pb concentrations (1.5 to 200 ppb) in 0.1 M HNO₃ (R² ⩾0.98). The electrode was feasible for measuring Pb in acid digests of the tested polished rices with measurement errors of <16.3 ppb. However, even though there was acceptable agreement in 4 of the 8 samples tested for Cd between the ASV and inductively coupled argon plasma (ICP) methods, further studies would be needed to improve the predictive capability of the electrode while reducing the variability in measurement and lowering the detection limit.