Resilient packet ring — IEEE 802.17

This article presents an overview of the main principles used in the resilient packet ring (RPR). This new ring network architecture is currently being standardized by the IEEE Working Group 802.17. Their goal is to provide a packet-based network technology — mainly to be used in metropolitan and wide area networks — with better efficiency, scalability and reduced costs compared to the existing circulit-oriented transmission network technology SONET/SDH.     

Investigation of the Thermal Diffusivity of Human Tooth Hard Tissue

Experiments of two kinds have been performed in which the heat diffusion effects in human tooth hard tissues have been investigated. The first one has been carried out on an incisor tooth as a whole with the use of a bath system. Experiments of the second kind have been done on slice specimens cut out of a tooth. A laser flash apparatus has been utilized. The time dependence of the temperature response has been measured using tiny thermocouples. The experimental data are then used to calculate the effective overall thermal diffusivity of the tooth structures as well as the thermal diffusivity of enamel and dentine alone. A discrepancy between the calculated results and literature data has been discussed.     

Digital simulation of the friction stir welding process

A recently developed welding process has proven to be well suited to making high strength aluminium alloy joints. This friction stir welding (FSW) process was invented and patented by The Welding Institute (TWI). The objective was to develop a means of simulating the process that could subsequently be used as a means of enhancing the design of these welded structures. Furthermore, these methods will enable easier development of the process, and for improved knowledge of the quality of the workpieces, in particular in terms of residual stresses. It will also make for better forecasting of the lifetime of these structures. These three-dimensional thermomechanical transient calculations were made using two finite element codes (SYSWELD (ESI Group) and MARC (MSc Group)). The heat input of the process was modelled by two different digital heat sources: a surface source with SYSWELD, and a volume source with MARC. The temperature results obtained are then compared with the experimental thermal measurements taken using thermocouples and an infrared camera. Neither the material flow nor the tool itself were modelled in the mechanical calculation. However, the mechanical characteristics of all the microstructure zones (Fig. 1) were factored into the calculations.     

Quantum size effect in absorption of low energy electrons in Pb layers

Absorption of low-energy electrons in Pb ultrathin layers grown on a Si(1 1 1)-(6×6)Au substrate has been measured as a function of the incident electron energy and of the film thickness. The thickness-dependent curves of the current revealed two distinct features. One of them is associated with the quantum size effect and showed the characteristic oscillatory behavior with the periodicity determined by the film thickness. The other, independent of the film thickness, was attributed to the bulk band structure of Pb.On the basis of the changes in the quantum size oscillations peak position as a function of the transmitted electron energy, and of the layer thickness, the electronic band structure of Pb 8-20 eV above the vacuum level has been determined in the ΓL direction.     

Machining performance of pearlitic–ferritic nodular cast iron with coated carbide and silicon nitride ceramic tools

This paper concerns the fundamental cutting characteristics obtained in the turning of the pearlitic–ferritic nodular iron (EN-GJS-500-7 grade with UTS=500 MPa) when using carbide tools coated with single TiAlN and multilayer TiC/Ti(C,N)/Al₂O₃/TiN coatings, as well as silicon nitride (Si₃N₄) based ceramic tools. As a competitor, a P20 uncoated carbide grade was selected. The fundamental process readings include cutting and feed forces, the tool–chip interface temperature, Peclet number, friction coefficient and the tool–chip contact length as functions of cutting parameters. In particular, the measurements of cutting temperature were carried out using conventional tool–work thermocouple method and IR thermography. It is concluded based on many process characteristics that multilayer coated and ceramic tools can substantially improve the performance of nodular iron machining.     

The effect of receptor-polymer matrix compatibility on properties of PEO-based polymer electrolytes containing a supramolecular additive: Part 1. Studies on phenomenon of compatibility

This paper presents the results of studies of poly(ethylene oxide)-based solid polymer electrolyte with the addition of anion receptor. The main stress is put on the influence of the anion receptor-polymeric matrix compatibility on the morphology of the composite. The comparison of the properties of two supramolecular compounds (calix[4]arene derivatives) having identical groups active in anion coordination in the narrow rim but with wide rim modified by groups having structure non-compatible and compatible to poly(ethylene oxide), is analyzed. The research of the system is made by means of vibrational (both IR and Raman) spectroscopies to evaluate the anion receptor-polymer–salt interactions. Raman and EDS mapping are used to determine the local concentration of the additive and salt. DSC and XRD determine the membrane crystallinity. Imaging techniques (both SEM and polarized light micrographs) allow to observe the morphology of membrane surface. The presented results show that additive distribution depends on the type of the receptor used and the phase of the polymer matrix (amorphous or crystalline).     

Treatment of effluents from the regeneration of ion exchangers using the MD process

The membrane distillation (MD) process for the treatment of wastewater from ion-exchanger regeneration was proposed. The precipitation of salt deposits on the membrane surface was observed when such wastewater was directly used as a feed. A rapid decline of the permeate flux from 532 to 410 dm³/m²d was found. The problem of fouling was significantly diminished by the addition of Ca(OH)₂ to the wastewater followed by filtration. The improvement of MD module performance was achieved after such pretreatment. The degree of water recovery equal to 50% was obtained without significant variations of the permeate flux. However, when the pretreated feed was subjected to two-fold concentration, precipitation of the silicon compounds was observed. The deposit caused clogging of the inlets of capillary membranes and resulted in a gradual decline of the module efficiency. The two-fold concentrated feed was then treated by sedimentation and filtration, which permitted a further concentration of obtained retentate and enhanced the degree of water recovery to 75%.     

Mathematical modelling of a LiBr–H2O absorption chiller including two-dimensional distributions of temperature and concentration fields for heat and mass exchangers

The paper presents the results of a theoretical analysis performed for a single-stage, water–lithium bromide absorption chiller at steady-state conditions. The model takes into consideration crosscurrent flow of fluids for heat and mass exchangers, two-dimensional distribution of temperature and concentration fields, local values of heat and mass transfer coefficients, thermal-parameter-dependent physical properties of working fluids and operation limits due to the danger of the LiBr–water hydrates and ice crystallisation. The main practical advantage of the model is the possibility to assess the influence of both the geometry parameters and operation parameters on thermal performance of the absorption chiller. The results derived from the implementation of the water vapour absorption process model for a horizontal tube absorber are consistent with the experimental measurements found in the literature.     

A comprehensive human chromosome 21 database.

The article presents a new, comprehensive, user-friendly chromosome 21 database driven by a built-in protein interaction prediction tool based on Markov random field (MRF) and GeneQuest, a novel easy-to-use user interface. The database contains a wide range of data including both in-house generated data (i.e., chromosome 21 orthologs) and data collected from other existing chromosome 21 databases (i.e., protein interactions, pathways, etc.). This article describes the underlying overall database design and data preparation, explains the underlying process of built-in protein-protein interaction prediction tool based on MRF including experimental results, presents details of the GeneQuest facilities, and illustrates the results and typical uses of the database     

Effects of coffee on the stability of accelerated aged poly(acrylonitryle‐butadiene‐styrene)

In food chemistry coffee is nowadays accepted as a rich source of compounds possessing antioxidant and radical scavenging activities. The aim of this work was to assess the influence of coffee on degradation properties of poly(acrylonitryle‐butadiene‐styrene) (ABS). Content of instant extract coffee powder varied from 0.1 to 0.5 wt %. The injection moulded samples were accelerated aged by means of heat treatment, UV‐Vis irradiation, and immersion in salt water. The influence of coffee on ABS properties were characterized by oxidation induction time (isothermal OIT), oxidation induction temperature (dynamic OIT), Fourier transform‐infrared spectroscopy (FT‐IR), UV‐Vis spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA). It was found that coffee effectively acted as an antioxidant, color, and structure stabilizer, maintaining mechanical properties close to the nonaged as compared with aged ABS. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39887.