Design for diagnosis using a diagnostic evaluation measure

The results demonstrated by the SAN system show how a real fault tolerant system can have more than one configuration with almost the same reliability. However, from a diagnosis perspective, the designs can have different costs of diagnosis at failure time. A method for measuring the cost of diagnosing diagnosis decision trees (DDT) was demonstrated, which is a specialized weighted mean depth of traversing the DDT. This evaluation method incorporates the qualitative (structure) and quantitative (reliability analysis) into one measure for predicting diagnosis cost. DDTs incorporate the same qualitative and quantitative data as the diagnosis cost measure, which makes this measure suitable for evaluating these decision trees. Evaluating and comparing alternative system designs using the diagnosis cost function as we demonstrated is an efficient and simple method for pursuing the design for diagnosis objective.     

Assessment of the reliability of an on-site MBR system for greywater treatment and the associated aesthetic and health risks.

This study analyses the reliability of an on-site MBR system for greywater treatment and reuse. To achieve this goal simulation was performed based on the IWA ASM1 model which was adapted to describe biological and physical mechanisms for MBR greywater treatment based systems. Model results were found to agree well with experimental data from an on site pilot greywater treatment plant, after which the calibrated model was used in a Monte Carlo mode for generating statistical data on the MBR system performance under different scenarios of failures and inflow loads variations. Effluents quality and their associated risks were successfully estimated.     

Hydrogen purification for fuel cell using CuO/CeO2-Al2O3 catalyst

CuO/CeO₂, CuO/Al₂O₃ and CuO/CeO₂-Al₂O₃ catalysts, with CuO loading varying from 1 to 5 wt.%, were prepared by the citrate method and applied to the preferential oxidation of carbon monoxide in a reaction medium containing large amounts of hydrogen (PROX-CO). The compounds were characterized ex situ by X-ray diffraction, specific surface area measurements, temperature-programmed reduction and temperature-programmed reduction of oxidized surfaces; XANES-PROX in situ experiments were also carried out to study the copper oxidation state under PROX-CO conditions. These analyses showed that in the reaction medium the Cu⁰ is present as dispersed particles. On the ceria, these metallic particles are smaller and more finely dispersed, resulting in a stronger metal-support interaction than in CuO/Al₂O₃ or CuO/CeO₂-Al₂O₃ catalysts, providing higher PROX-CO activity and better selectivity in the conversion of CO to CO₂ despite the greater BET area presented by samples supported on alumina. It is also shown that the lower CuO content, the higher metal dispersion and consequently the catalytic activity. The redox properties of the ceria support also contributed to catalytic performance.     

Feasibility study of automated detection of tunnel excavation by Brillouin optical time domain reflectometry

Cross-borders smuggling tunnels enable unmonitored movement of people, drugs and weapons and pose a very serious threat to homeland security. Recent advances in strain measurements using optical fibers allow the development of smart underground security fences that could detect the excavation of smuggling tunnels. This paper presents the first stages in the development of such a fence using Brillouin optical time domain reflectometry (BOTDR). Two fiber optic layouts are considered and evaluated in a feasibility study that includes evaluation of false detection and sensitivity: (1) horizontally laid fiber buried at a shallow depth, and (2) fibers embedded in vertical mini-piles. In the simulation study, two different ground displacement models are used in order to evaluate the robustness of the system against imperfect modeling. In both cases, soil–fiber and soil-structure interactions are considered. Measurement errors, and surface disturbances (obtained from a field test) are also included in the calibration and validation stages of the system. The proposed detection system is based on wavelet decomposition of the BOTDR signal, followed by a neural network that is trained to recognize the tunnel signature in the wavelet coefficients. The results indicate that the proposed system is capable of detecting even small tunnel (0.5 m diameter) as deep as 20 m (under the horizontal fiber) or as far as 10 m aside from the mini-pile (vertical fiber), if the volume loss is greater than 0.5%.     

Cell-based dynamic heat exchanger models—Direct determination of the cell number and size

Large amounts of thermal energy are transferred between fluids for heating or cooling in industry as well as in the residential and service sectors. Typical examples are crude oil preheating, ethylene plants, pulp and paper plants, breweries, plants with exothermic and endothermic reactions, space heating, and cooling or refrigeration of food and beverages. Heat exchangers frequently operate under varying conditions. Their appropriate use in flexible heat exchanger networks as well as maintenance/reliability related calculations requires adequate models for estimating their dynamic behaviour. Cell-based dynamic models are very often used to represent heat exchangers with varying arrangements. The current paper describes a direct method and a visualisation technique for determining the number of the modelling cells and their size.     

Graphene foam resonators:Fabrication and characterization

Three-dimensional graphene foams(GFs)benefit from a large surface area and unique physical properties.We present here the first-ever miniaturized GF-based resonators.We developed a simple yet reliable fabrication process,in which GFs are synthesized and assembled on a cavity to form suspended GF devices.We electrostatically excited these devices and analyzed their resonance and ring-down responses.We observed significant energy dissipation,as the quality factor of the devices was in the order of several tens.Additionally,we investigated the influence of temperature on the operation of the devices and found that high temperatures mechanically soften the resonators but also considerably enhance energy dissipation.Finally,our devices demonstrated a mode-coupling of a resonance mode and a mode having twice its frequency.Thus,this work paves the way toward the development of novel GF resonators that could be integrated into future devices,such as GF-based nano-electromechanical sensors,electrical circuits,and oscillators.     

Artifact‐Free Quantification and Sequencing of Rare Recombinant Viruses by Using Drop‐Based Microfluidics

Recombination is an important driver in the evolution of viruses and thus is key to understanding viral epidemics and improving strategies to prevent future outbreaks. Characterization of rare recombinant subpopulations remains technically challenging because of artifacts such as artificial recombinants, known as chimeras, and amplification bias. To overcome this, we have developed a high‐throughput microfluidic technique with a second verification step in order to amplify and sequence single recombinant viruses with high fidelity in picoliter drops. We obtained the first artifact‐free estimate of in vitro recombination rate between murine norovirus strains MNV‐1 and WU20 co‐infecting a cell (P_rec=3.3×10^?4±2×10^?5) for a 1205 nt region. Our approach represents a time‐ and cost‐effective improvement over current methods, and can be adapted for genomic studies requiring artifact‐ and bias‐free selective amplification, such as microbial pathogens, or rare cancer cells.     

Biodegradable amphiphiles of grafted poly(lactide) onto 2‐hydroxyethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers as drug carriers

This article describes the synthesis and characterization of 2‐hydroxylethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers, (HEMA‐co‐NVP), via free radical polymerization followed by grafting of poly(lactide) onto (HEMA‐co‐NVP) copolymers, via ring opening polymerization using tin octoate as a catalyst. The copolymers and the grafted copolymers (i.e., amphiphiles) were subjected to sustained release studies using salicylic acid, as a model drug. Characterization of the formed copolymers was performed using ¹H‐NMR, ¹³C‐NMR, FTIR, TGA, DSC, and SEM techniques. Derivative of TGA thermogram was used to determine %hydrophilicity and %hydrophobicity in the grafted and ungrafted copolymers. The SEM morphology revealed porous layers with crispy structure that were most likely due to the presence of poly(lactide) chains. At lower content of poly(lactide) moiety, grafted copolymers showed non‐Fickian diffusion release rate, whereas Fickian diffusion release rate at higher content of poly(lactide) was observed. The increase of poly(lactide) content (i.e., larger %hydrophobicity) in the copolymer increased the drug‐sustainability, due to the consistent but porous amphiphilic degradable structures that allow controllable release of drug in time interval. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011