Lipase‐catalyzed dynamic hydrolytic resolution of (R,S)‐2,2,2‐trifluoroethyl α‐chlorophenyl acetate in water‐saturated isooctane

The hydrolytic resolution of (R,S)‐2,2,2‐trifluoroethyl α‐chlorophenylacetate in water‐saturated isooctane containing Lipase MY(I) at 35 °C is selected as the best reaction condition for producing (R)‐α‐chlorophenyl acetic acid. The kinetic constants, and hence an enantiomeric ratio of 33.6, are estimated and employed for the modeling of time‐course conversions of both substrates by considering product inhibition and enzyme deactivation effects. A successful dynamic kinetic resolution is also achieved, giving the desired (R)‐α‐chlorophenylacetic acid of 93.0% yield and ee_P = 89.5% when 80 mmol dm^?3 trioctylamine acting as the racemization catalyst and enzyme activator is initially added. Copyright © 2006 Society of Chemical Industry     

Mining predecessor–successor rules from DAG data

Data mining extracts implicit, previously unknown, and potentially useful information from databases. Many approaches have been proposed to extract information, and one of the most important ones is finding association rules. Although a large amount of research has been devoted to this subject, none of it finds association rules from directed acyclic graph (DAG) data. Without such a mining method, the hidden knowledge, if any, cannot be discovered from the databases storing DAG data such as family genealogy profiles, product structures, XML documents, task precedence relations, and course structures. In this article, we define a new kind of association rule in DAG databases called the predecessor–successor rule, where a node x is a predecessor of another node y if we can find a path in DAG where x appears before y. The predecessor–successor rules enable us to observe how the characteristics of the predecessors influence the successors. An approach containing four stages is proposed to discover the predecessor–successor rules. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 621–637, 2006.     

An effective neuro-fuzzy paradigm for machinery condition healthmonitoring

An innovative neuro-fuzzy network appropriate for fault detection and classification in a machinery condition health monitoring environment is proposed. The network, called an incremental learning fuzzy neural (ILFN) network, uses localized neurons to represent the distributions of the input space and is trained using a one-pass, on-line, and incremental learning algorithm that is fast and can operate in real time. The ILFN network employs a hybrid supervised and unsupervised learning scheme to generate its prototypes. The network is a self-organized structure with the ability to adaptively learn new classes of failure modes and update its parameters continuously while monitoring a system. To demonstrate the feasibility and effectiveness of the proposed network, numerical simulations have been performed using some well-known benchmark data sets, such as the Fisher's Iris data and the Deterding vowel data set. Comparison studies with other well-known classifiers were performed and the ILFN network was found competitive with or even superior to many existing classifiers. The ILFN network was applied on the vibration data known as Westland data set collected from a U.S. Navy CH-46E helicopter test stand, in order to assess its efficiency in machinery condition health monitoring. Using a simple fast Fourier transform (FFT) technique for feature extraction, the ILFN network has shown promising results. With various torque levels for training the network, 100% correct classification was achieved for the same torque Levels of the test data.     

2010 IEEE CIS Awards [Society News]

Including: Neural Networks Pioneer Vladimir Vapnik, NEC Research, Inc., USA. Fuzzy Systems Pioneer Hideo Tanaka, Hiroshima International University, JAPAN. Evolutionary Computation Pioneer David E. Goldberg, University of Illinois at Urbana Champaign, USA and John Grefenstette, George Mason University, USA. Meritorious Services James M. Keller, University of Missouri, USA. IEEE Transactions on Fuzzy Systems Outstanding Paper, IEEE Transactions on Evolutionary Computation Outstanding Paper, Outstanding Chapter, Outstanding Ph.D. Dissertation. Also past CIS Neural Networks Pioneer Awardees, Fuzzy Systems Pioneer Awardees, Evolutionary Computation Pioneer Awardees and Meritorious Service Awardees.     

Effect of LiClO4 on the thermal and morphological properties of organic/inorganic polymer hybrids

This paper describes the thermal properties, morphologies, and interactions within the binary and ternary blends of poly(methyl methacrylate) (PMMA), octa(phenol)octasilsesquioxane (OP-POSS), and LiClO₄. In the binary PMMA/OP-POSS blends, the OP-POSS molecules tend to aggregate and result in a decrease (19 °C) in the glass transition temperature. In the ternary PMMA/LiClO₄/OP-POSS blends, however, the OP-POSS molecules form small sphere-like domains (20 nm) leading to the composite's glass transition temperature increasing by up to 30 °C. Based on these FT-IR spectra, the addition of LiClO₄ influenced the probability of hydrogen bonds formed between PMMA and OP-POSS and these SEM micrographs, DSC, and XRD data indicated that the addition of LiClO₄ is a convenient and simple approach toward dispersing the OP-POSS nanoparticles within PMMA, where the presence of LiClO₄ changes the physical effect of OP-POSS from that of a diluent role to a cross-linker role.     

Pervaporation performance and Transport phenomenon of PVA blend membranes for the separation of THF/water azeotropic mixtures

Summary Dense polymer membranes were made by mixing aqueous solutions of hydrophilic polymers poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI) in different ratios for investigating the separation of Tetrahydrofuran (THF)/water azeotropic mixtures by pervaporation (PV). In order to gain a more detailed picture of the molecular transport phenomenon, we have performed sorption gravimetric experiments at 30 °C to compute diffusion, swelling, sorption and permeability coefficients of PVA/PEI membranes in the presence of THF and water. The membranes were found to have good potential for breaking the azeotrope of THF at 6% concentration of water. An increase in PVA content in the blend caused a reduction in the flux and an increase in selectivity. Among the blends tested in the study, the 5:1 PVA/PEI blend membrane showed the highest separation factor of 181.5, exhibited a flux of 1.28 kg/m²h for THF respectively at azeotropic feed composition.     

A simple control scheme for a single stage flyback LED driver

This study proposes a simple control scheme for using single‐stage flyback (SSF) converters in lighting source applications for LEDs. Among the advantages of the average current mode is an I/O current ripple that is only one‐half of the critical conduction mode (CRM). This condition helps extend the output capacitor lifetime while lowering the input EMI capacitance input EMI capacitance. The SSF converter proposed in this study operates in continuous conduction mode (CCM). In addition, two sample‐and‐hold (S/H) circuits are placed at the output voltage loop and feed‐forward path, respectively. Since these S/H circuits access the average output current and average feed‐forward voltage, the LED driver is unaffected by the 120‐Hz ripple noise, the total harmonic distortion (THD) is reduced, and the transient response of the output current is improved. Finally, the operation principles and design considerations of the studied LED driver are analyzed and discussed. A laboratory prototype is also designed and tested to verify the feasibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Fluorescent lamp model with power and temperature dependence for high-frequency electronic ballasts

The electrical behavior of a fluorescent lamp operating at high frequency can be characterized by a resistance. The lamp equivalent resistance varies with the operating power and ambient temperature. On this basis, an electrical circuit model of the fluorescent lamp for high-frequency steady-state operation is developed. A test system is set up to emulate the dimming operation of fluorescent lamps in a temperature range from -15/spl deg/C to 55/spl deg/C. For a given lamp, the voltage equation can be obtained from few test data. Then, the equations for the arc current and the equivalent resistance can be derived. These lamp equations can be used for predicting the operating characteristics of the dimmable ballast-lamp circuits with considerations on the temperature effects. The verification of the proposed lamp model is illustrated by implementation examples.