Comparative study of aromatic polyimides containing methylene units

Two series of aromatic polyimides have been synthesized by solution polycondensation of certain aromatic dianhydrides with two aromatic diamines containing methylene groups; one of the diamines has also a methyl substituent on each benzene ring. These polymers have been studied with regard to their solubility, thermal stability, film forming ability, and mechanical properties of their films.     

Design of a Three-Phase Flux Reversal Machine

A comprehensive design of a novel doubly-salient, stator-permanent magnet (PM) three-phase flux reversal machine (FRM) is presented in this paper. FRM has a robust and easy-to-build structure and is suitable for high-speed applications. Detailed design procedures and formulae are given. All of the dimensions of the FRM are derived. Basic parameters are calculated. The most important aspect of this design is to consider the wide operating speed range. The work presented may serve as a guideline for the general principle of design on three-phase FRM. Furthermore, the methodology and formulae introduced in this paper are also applicable to other types of PM and/or reluctance machine.     

IMS10-image-based milling toolpaths with tool engagement control for complex geometry

This paper presents a NC toolpath generation strategy with tool engagement control for arbitrarily complex discrete part geometry, which reduces machining time and tool wear and can be used in high speed machining. The toolpath computation is based on image models for design part, raw stock and cutting tool, and involves pixel-based simulation of the milling process. Simulation results and comparison with existing methods are presented.     

Optimization of synthesis parameters in interfacial polycondensation using design of experiments

The reaction of phenylphosphonic dichloride with 4,4′-cyclohexylidenebisphenol by a gas–liquid interfacial polycondensation was investigated. The design of experiments (DoE) method is used for determination of the best reaction conditions. The correlation of simultaneous influence of the parameters (reaction time, reaction temperature, alkaline medium, reagents molar ratio) on yield and inherent viscosity was studied.     

Integrated analytical study for the authentication of five Russian icons (XVI–XVII centuries)

This article presents an integrated approach for the authentication of five Russian icons through the study of their paint materials (elemental composition and stratigraphic mapping), state of conservation and artistic technique. The results of the applied analytical protocol, involving optical and scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry and Fourier transformed infrared spectroscopy/microspectroscopy, led to the conclusion that the five icons belong to the same group and iconographic school (from Northern Russia) and date from the end of the 16th century to the beginning of 17th century. Because of massive overpainting, the icons “suffered” a change in iconographic style and significance, and restoration treatment brought to light the original painting and its attribution. Identification of the composition of the original chromatic palette used by the iconographer, the stratigraphic mapping and the conservation state of the painting materials, along with the features of the original artistic technique, furnished key elements for the icons' authentication. Here, we present the first experimental data concerning the identification of the authentication characteristics, being part of a large project that has as its final aim the evaluation of the effectiveness and effects of the cleaning agent on the paint layers. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.     

The viscosity of dimethyl ether

Dimethyl ether (DME) has been recognised as an excellent fuel for diesel engines for over one decade now. Engines fuelled by DME emit virtually no particulate matter even at low NO_x levels. This is only possible in the case of diesel oil operation if expensive and efficient lowering particles and NO_x traps are installed.The most significant problem encountered when engines are fuelled with DME is that the injection equipment breaks down prematurely due to extensive wear. This tribology issue can be explained by the very low lubricity and viscosity of DME. Recently, laboratory methods have appeared capable of measuring these properties of DME. The development of this is rendered difficult because DME has to be pressurised to remain in the liquid state and it dissolves most of the commercially available elastomers.This paper deals fundamentally with the measurement of the viscosity of DME and extends the discussion to the difficulty of viscosity establishing of very thin fluids. The main issue here is that it is not easy to calibrate the viscometers in the very low viscosity range corresponding to about one-fifth of that of water. The result is that the low viscosity is measured at high Reynolds numbers so that the outcome has to be corrected by various factors. The validity of these can be discussed especially when they exceed a few percent of the apparent viscosity.The volatile fuel viscometer (VFVM) developed at DTU is presented. By enclosing a standard glass capillary viscometer in a glass tube it is possible to measure the viscosity of fluids at pressures below 15 bars. The kinematic viscosity of DME was established at 0.184 cSt @ 25 °C at the vapour pressure of the fluid at that temperature. The measurements were made at reasonable Reynolds numbers so the correction factors are negligible indicating a high accuracy of the method.Other pressurised viscometers have appeared since the development of the VFVM. These predict a 5–19% higher viscosity for DME than the VFVM. It seems that the causes for these differences are a too high Reynolds number and/or an influence of the gas used for pressurisation in these methods. The results of the VFVM are consolidated by measurements of the viscosities of propane and butane: these agree with the outcome of measurements using a quartz crystal microbalance (QCM) a method that is supposedly less sensible than the Reynolds number.     

Intuitionistic fuzzy similarity measures based on min–max operators

Pattern Analysis and Applications - Intuitionistic fuzzy sets, introduced by Atanassov, offer a new possibility to describe in a more adequate way many real problems. An important tool for...     

The Romanian wordnet in a nutshell

The project on the Romanian wordnet has been under continuous development for more than 10 years now. It has been in constant use in many projects and applications which determined, to a large extent, the content and coverage of various lexical domains. The article presents the most recent developments of the Romanian wordnet and offers quantitative data for its current version.     

核医学数据获取动态存储器的设计

介绍了核医学图像数据获取的基本方法和与计算机的接口，重点介绍接口中数据获取动态存储器的设计，给出了硬件电路和设计原理。     

Hybrid nanostructured coating for increased resistance of prosthetic devices to staphylococcal colonization

Prosthetic medical device-associated infections are responsible for significant morbidity and mortality rates. Novel improved materials and surfaces exhibiting inappropriate conditions for microbial development are urgently required in the medical environment. This study reveals the benefit of using natural Mentha piperita essential oil, combined with a 5 nm core/shell nanosystem-improved surface exhibiting anti-adherence and antibiofilm properties. This strategy reveals a dual role of the nano-oil system; on one hand, inhibiting bacterial adherence and, on the other hand, exhibiting bactericidal effect, the core/shell nanosystem is acting as a controlled releasing machine for the essential oil. Our results demonstrate that this dual nanobiosystem is very efficient also for inhibiting biofilm formation, being a good candidate for the design of novel material surfaces used for prosthetic devices.