Studies on the properties of glass fiber reinforced epoxy composites of DGEBA / epoxidized polyhydric alcohols with or without fortifier

Differential scanning calorimetry (DSC) technique was used to study the curing reaction of diglycidyl ether of bisphenol A (DGEBA) resin and different di- and trifunctional polyhydric alcohols with phthalic anhydride as curing agent and triethylamine as catalyst with or without fortifier. The thermal stability of the cured products was also studied by thermogravimetric analysis (TGA). Using these data, different glass fiber reinforced epoxy composites were fabricated and their mechanical and electrical properties and their resistance to chemicals were studied as well. Activation energies of curing reactions range within 75.1 to 88.3 kJ mol^?1. The cured products have good thermal stability; the composites have good mechanical strength, electrical insulation properties and chemical resistance. 36 to 53% improvement in flexural strength has been observed when fortifier was added to the DGEBA-diluent systems.     

Synthesis of Niobium(V)-Stabilized Tetragonal Zirconia Nanocrystalline Powders

The polymer precursor method is very useful to prepare Nb⁵⁺-stabilized nanocrystalline powders of t -ZrO₂. The precursor solution is composed of zirconium oxalate, niobium tartrate, and poly(vinyl alcohol), which help to form a network matrix to disperse the metal ions homogeneously. Nb⁵⁺ is an effective agent to stabilize t -ZrO₂, and ease of formation of the tetragonal phase increases with increasing dopant concentration. Thermal stability of t -phase is found up to 1700°C having 15 mol% Nb⁵⁺, prepared at 600°C with particle sizes of 35 ± 5 nm.     

Redefining the Game in Local Water Management Conflict: A Case Study

The article intends to bring a new perspective on conflict and cooperation analysis addressing a case study of Yoshino river weir conflict (Japan) by the use of drama theory approach. The confrontation arose when the Governmental agency proposed to remove and replace the old weir by a movable modern dam (kodazeki) to prevent future flooding. The Opposition group’s main arguments were that the new weir may not be as effective as compared to the cost of constructing the new renewal project and damage of water quality and ecosystem. Thus, both players are playing the game where their interests are different. Rather than adopting the conventional approach of modeling the conflict using game theory, we propose the alternative approach to describe how the situation evolved and how game can be changed in the context of player’s threats and promises. This also emphasizes that future can be created cooperatively by a group, rather than by way of confrontation in the conflict. This model may bring an effective methodological leverage in conflict and cooperation analysis where we can change the game.     

A new miniature electrical aerosol spectrometer (MEAS): Experimental characterization

Design and theory of a new compact ultrafine particle sizing instrument, called the miniature electrical-mobility aerosol spectrometer (MEAS), was recently introduced [Ranjan, M., & Dhaniyala, S. (2007). A new miniature electrical spectrometer: Theory and design. Journal of Aerosol Science, 39, 950–963]. In the MEAS, electrostatic precipitation technique is used for both generation of sheath flow and classification of particles based on their electrical mobility. An electrometer-array, connected to the collection electrodes in the classifier section, is used to measure the number of particles collected in the different mobility channels, and these data are inverted using MEAS transfer functions to obtain particle number size distributions. Design of a prototype MEAS and the experimental approach to validate the performance of the individual components of the instrument are presented. Particle size distributions obtained from MEAS measurements compare well with those obtained using a scanning mobility particle sizer (SMPS; TSI 3936), validating theoretical calculations of instrument transfer functions. The operational limits of MEAS are determined from the calculation of error in the inverted size distribution as a function of total particle concentration. This analysis suggests that the designed MEAS can be used for applications such as personal and ambient monitoring under conditions of moderate to high particle concentrations.     

Assessment of snowmelt triggered landslide hazard and risk in Japan

This study is pertaining to an evaluation of landslide occurrence on natural terrain due to snowmelt in Japan, using a probabilistic model based on multiple logistic regression analysis. The evaluation concerns several physical parameters such as hydraulic parameters, geographical parameters and geological parameters which are considered to be influential in the occurrence of landslides. A Snow Water Equivalent model (SWE) is utilized to estimate snowmelt and associated infiltration in light, heavy and normal snow years. Using the constructed spatial data-sets, we apply a multiple logistic regression model to produce landslide susceptibility maps showing the spatial–temporal distribution of landslide hazard probabilities throughout Japan using 1 km × 1 km resolution grid cells. The results have revealed that, over 95% landslide hazard probability exists in the mountain ranges on the western side of Japan (the Japan Sea side). In particular, this study is dealing with the Aizu region of Fukushima prefecture in order to verifying the landslide hazard probability. Verification proved that, the areas identified as high risk areas (having over 90% landslide hazard probability in numerical modeling) show 87% agreement with observed landslides in the Aizu region. Also we evaluated the relationship between landslides and snow melting process giving special concern to change of temperature in the spring.     

Removal of anionic dyes from aqueous solution using poly [N-vinyl pyrrolidone/2-(methacryloyloxyethyl) trimethyl ammonium chloride] superswelling hydrogels

Summary A superswelling poly [N-vinyl pyrrolidone/2-(methacryloyloxyethyl)trimethyl ammonium chloride], poly(NVP/METAC) hydrogels were prepared by free radical polymerization using ethylene glycol dimethacrylate as crosslinker. The hydrogels were characterized by FT-IR spectroscopy and their surface morphology was determined using Scanning Electron Microscope (SEM). The influence of feed composition of both the monomers and crosslinker on equilibrium swelling and dye adsorption properties of the hydrogels were examined. The equilibrium swelling ratio and binding ratio of the hydrogel/dye systems greatly depends on the METAC and crosslinker concentration in the gels. The effects of pH of the medium and initial dye concentration on the adsorption were also studied. The binding ratio of the hydrogel/dye system increases in the following order: OR-II>RO-14>RO-13.     

Peer-to-peer-based resource discovery in global grids: a tutorial

An efficient resource discovery mechanism is one of the fundamental requirements for grid computing systems, as it aids in resource management and scheduling of applications. Resource discovery activity involves searching for the appropriate resource types that match the user's application requirements. Various kinds of solutions to grid resource discovery have been suggested, including centralized and hierarchical information server approaches. However, both of these approaches have serious limitations in regard to scalability, fault tolerance, and network congestion. To overcome these limitations, indexing resource information using a decentralized (e.g., peer-to-peer (P2P)) network model has been actively proposed in the past few years. This article investigates various decentralized resource discovery techniques primarily driven by the P2P network model. To summarize, this article presents a: summary of the current state of the art in grid resource discovery, resource taxonomy with focus on the computational grid paradigm, P2P taxonomy with a focus on extending the current structured systems (e.g., distributed hash tables) for indexing d-dimensional grid resource queries,1 a detailed survey of existing work that can support rf-dimensional grid resource queries, and classification of the surveyed approaches based on the proposed P2P taxonomy. We believe that this taxonomy and its mapping to relevant systems would be useful for academic and industry-based researchers who are engaged in the design of scalable grid and P2P systems.     

New Research on AC–AC Converters without Intermediate Storage and Their Applications in Power-Electronic Transformers and AC Drives

AC-AC converters (e.g. matrix converters) are mostly semiconductor solutions for applications where intermediate energy storage is eliminated. This paper summarizes the research done and being carried out at the University of Minnesota for applications in motor drives and power-electronic transformers with advanced features. This paper presents a carrier-based modulation method for matrix converters and its application during for both input unbalance and output over-modulation. Various topologies of matrix converter are described for both drives and power-electronic transformers. These topologies have some inherent benefits like common-mode voltage elimination across the bearings of the motor/generator and controllable power factor at the input side. Some of the described technologies require open-ended machines as load and thereby some advantages like enhanced output voltage (1.5 times the output of normal three terminal load) are achieved. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Influence of limestone particle size on iron ore sinter properties and productivity

Iron ore fluxed sinter is the main ferrous burden of Jindal south west steel limited (JSWSL) blast furnaces. In sinter plant fluxes including limestone and dolomite are added to improve the sinter properties of iron ore and to provide an appropriate slag composition of the blast furnace. The raw material grain size affects the sinter process considerably because the sinter productivity and quality are strongly dependent on the green permeability of the bed, which is determined by the particle size distribution of the raw materials, the granulation effectiveness and by the sintering process itself. It is well‐known that in fluxed sinter, the size of limestone affects productivity and physical and metallurgical properties of the sinter. It is therefore necessary to understand the role of limestone particle size on sinter properties and productivity. In the present work laboratory sintering experiments have been carried out with different levels of limestone mean particle size (from 0.14 to 1.83mm) to understand the influence of limestone particle size on mineralogy, productivity, physical and metallurgical properties of the sinter. Sinter productivity increased with increasing limestone mean particle size due to improved sinter bed permeability. Sinter with limestone mean particle size of 1.25 to 1.52 mm yielded better sinter strength and lower RDI compared to sinter with smaller or larger limestone mean particle size. Higher sinter strength is due to better and uniform distribution of limestone particles, and better bed permeability enabled easy assimilation and effective distribution of calcium ferrite phases. The improvement in sinter RDI is due to change in mineralogy of the sinter compared to coarser and finer limestone mean particle size.