Probabilistic approach for QoS-aware recommender system for trustworthy web service selection

We present a QoS-aware recommender approach based on probabilistic models to assist the selection of web services in open, distributed, and service-oriented environments. This approach allows consumers to maintain a trust model for each service provider they interact with, leading to the prediction of the most trustworthy service a consumer can interact with among a plethora of similar services. In this paper, we associate the trust in a service to its performance denoted by QoS ratings instigated by the amalgamation of various QoS metrics. Since the quality of a service is contingent, which renders its trustworthiness uncertain, we adopt a probabilistic approach for the prediction of the quality of a service based on the evaluation of past experiences (ratings) of each of its consumers. We represent the QoS ratings of services using different statistical distributions, namely multinomial Dirichlet, multinomial generalized Dirichlet, and multinomial Beta-Liouville. We leverage various machine learning techniques to compute the probabilities of each web service to belong to different quality classes. For instance, we use the Bayesian inference method to estimate the parameters of the aforementioned distributions, which presents a multidimensional probabilistic embodiment of the quality of the corresponding web services. We also employ a Bayesian network classifier with a Beta-Liouville prior to enable the classification of the QoS of composite services given the QoS of its constituents. We extend our approach to function in an online setting using the Voting EM algorithm that enables the estimation of the probabilities of the QoS after each interaction with a web service. Our experimental results demonstrate the effectiveness of the proposed approaches in modeling, classifying and incrementally learning the QoS ratings.     

Optimized conditions for the grafting reaction of poly(methyl acrylate) onto rubberwood fiber

Graft copolymerization of poly(methyl acrylate) (PMA) onto rubberwood fiber (RWF) was carried out by free radical initiation. Hydrogen peroxide and ferrous ions were used as an initiator system. Effects of various parameters (reaction temperature and reaction time, as well as hydrogen peroxide, ferrous ammonium sulfate and monomer concentrations) on the grafting percentage were investigated. A high percentage of grafting was achieved when optimum reaction conditions were used. The optimum temperature of the reaction was determined to be about 55 °C and the reaction time was 120 min. The optimum concentration of H₂O₂ was 0.03 M and the amounts of Fe²⁺ and MA were 0.4 mmol and 0.05 mol, respectively. The PMA homopolymer was removed from the graft copolymer by Soxhlet extraction using acetone. The presence of PMA on the fiber was confirmed by FT-IR spectroscopy and gravimetry. The surface morphology of the poly(methyl acrylate)-graft-(rubberwood fiber) was studied by means of scanning electron microscopy. Copyright © 2004 Society of Chemical Industry     

Thermophilic Campylobacter spp. in salad vegetables in Malaysia

The main aim of this study was to combine the techniques of most probable number (MPN) and polymerase chain reaction (PCR) for quantifying the prevalence and numbers of Campylobacter spp. in ulam, a popular Malaysian salad dish, from a traditional wet market and two modern supermarkets in Selangor, Malaysia. A total of 309 samples of raw vegetables which are used in ulam were examined in the study. The prevalences of campylobacters in raw vegetables were, for supermarket I, Campylobacter spp., 51.9%; Campylobacter jejuni, 40.7%; and Campylobacter coli, 35.2%: for supermarket II, Campylobacter spp., 67.7%; C. jejuni, 67.7%; and C. coli, 65.7%: and for the wet market, Campylobacter spp., 29.4%; C. jejuni, 25.5%; and C. coli, 22.6%. In addition Campylobacter fetus was detected in 1.9% of raw vegetables from supermarket I. The maximum numbers of Campylobacter spp. in raw vegetables from supermarkets and the wet market were >2400 and 460 MPN/g, respectively.     

Formation of dot arrays with a pitch of 20 nm × 20 nm for patterned media using 30 keV EB drawing on thin calixarene resist

We studied the possibility of achieving very fine-pitch dot arrays with a pitch of 20?nm × 20?nm using 30?keV electron beam (EB) drawing on negative calixarene resist. In order to form such patterns, we studied the dependence on resist thickness of the dot size and the packing. We propose EB drawing on an extremely thin film for very highly packed dot-array formation. Our experimental results demonstrate the possibility of forming highly packed dot-array patterns with a pitch of 20?nm × 20?nm and a resist thickness of about 13?nm, which corresponds to about 1.6?Tbits?in(-2).     

Evaluation of adhesion strength,flammability, and degradation of HBCD‐containing polyurethane adhesives

In this work, moisture curable flame retardant HTPB‐based polyurethane adhesives were synthesized. The influence of HBCD (Hexabromocyclododecane) as flame retardant on adhesion, degradation and change in flammability of synthesized HTPB‐based polyurethane has been studied. Relationship between phase separation in hard and soft domains and adhesion has also been investigated. FTIR analysis was used to determine phase separation in synthesized adhesives. Lap shear test was used to determine adhesion properties of adhesives applied on aluminum and glass substrates. Thermal Gravimetry analysis and Limited Oxygen Index (LOI) tests were carried out on flame retardant adhesives to evaluate effect of HBCD on degradation and flammability. Addition of HBCD to adhesives leads to reduction of thermal stability and lap shear strength for all substrates, in spite of flame retardant adhesives show higher LOI value. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A hybrid experimental-numerical approach for load rating of reinforced concrete bridges with insufficient structural properties

This article presents a non-destructive approach for load rating of reinforced concrete bridges without structural plans. The approach is found on a hybrid method, which employs vibration and live load testing coupled with numerical simulation and model updating techniques, to converge on estimate of unknown structural parameters. The material properties of bridge and the amount of reinforcing steel for calculating the bending capacity of a bridge are determined through model updating results and nondestructive approaches. The updated model is then employed to determine load effects for calculating load rating factors, and these results are combined with live load test result to arrive at the bridge capacity, and ultimately the load rating. The method is validated by testing a skewed reinforced concrete slab bridge for load rating purposes. The bridge was instrumented with accelerometers and strain gages, and the responses of the bridge under vibration and quasi-static tests were measured. Results demonstrated that the proposed method is capable of determining the bridge capacity and load rating factor with good accuracy, and not only can be used for load rating of concrete bridges without structural information, but also can be useful in condition assessment of existing concrete bridge with available as-built information.     

Electron Beam Irradiation for Mercury Oxidation and Mercury Emissions Control

A variety of air pollution control strategies have been investigated to reduce mercury emissions from coal-fired sources. The most developed and deployed technologies are based on adsorption of mercury onto powdered activated carbon followed by carbon collection. Mercury oxidation over selective catalytic reduction catalysts followed by wet scrubbing is another potential technique, and tests suggest that emissions reductions of 20–80% are possible, but test results are variable and ultrahigh removal (95%+) is unusual. The objective of this study was to investigate the effectiveness of electron beam irradiation to oxidize mercury vapor, to improve mercury removal with wet scrubbers or wet electrostatic precipitators (ESPs). Metallic mercury vapor samples in air and other atmospheres were prepared at concentrations of approximately 16?μg/m3. Samples were electron irradiated at energy levels of 2.5–10 kGy, equivalent to 3.1–12.4?kJ/m3 stack gas. Results show that mercury oxidation rate was dependent on both the gaseous atmosphere composition and the irradiation energy level. At medium energy levels, approximately 98% of gaseous mercury vapor was readily oxidized. Electron beam irradiation demonstrated high levels of mercury oxidation at the bench scale, and the technology might help improve mercury removal in wet scrubbers or wet ESPs when employed as a primary or secondary mercury oxidation technique.     

ZnCl2- and NH4Cl-hydroponics gel electrolytes for zinc–carbon batteries

Absorbency testing is used to determine the percentage of ZnCl₂ or NH₄Cl solution absorbed by a hydroponics gel (HPG). It is found that the absorbency of ZnCl₂ or NH₄Cl solution decreases with increasing solution concentration. The conductivity of ZnCl₂- and NH₄Cl-HPG electrolytes is dependent on the solution concentration. A mixture of salt solution with HPG yields excellent gel polymer electrolytes with conductivities of 0.026 and 0.104 S cm⁻¹ at 3 M ZnCl₂ and 7 M NH₄Cl, respectively. These gel electrolytes are then used to produce zinc–carbon cells. The fabricated cells give capacities of 8.8 and 10.0 mAh, have an internal resistance of 25.4 and 19.8 Ω, a maximum power density of 12.7 and 12.2 mW cm⁻², and a short-circuit current density of 29.1 and 33.9 mA cm⁻² for ZnCl₂- and NH₄Cl-HPG electrolytes, respectively.     

Lattice Boltzmann simulation of natural convection in an open ended cavity

Natural convection in an open ended cavity is simulated using Lattice Boltzmann Method (LBM). The paper is intended to address the physics of flow and heat transfer in open end cavities and close end slots. The flow is induced into the cavity by buoyancy force due to a heated vertical wall. Also, the paper demonstrated that open boundary conditions used at the opening of the cavity is reliable, where the predicted results are similar to conventional CFD method (finite volume method, FVM) predictions. Prandtl number (Pr) is fixed to 0.71 (air) while Rayleigh number (Ra) and aspect ratio (A) of the cavity are changed in the range of 10⁴–10⁶ and of 0.5–10, respectively. It is found that the rate of heat transfer deceases asymptotically as the aspect ratio increases and may reach conduction limit for large aspect ratio. The flow evaluation in the cavity starts with recirculation inside the cavity, as the time proceeds the flow inside the cavity communicates with the ambient.