Mechanical behaviour of an austempered ductile iron

Austempering of a ferrite-pearlitic grade of ductile iron was carried out to assess the potential use of the material for crank shaft application reported. A commercial material was austempered at 340°C to realize the properties. The austempered ductile iron gave good strength although the ductility values were lower. The material developed had complete ausferritric structure free of pearlite. The various phase constitution and phase transformation associated with the treatment and during mechanical deformation was examined. Using XRD analysis the volume fraction of the austenite in the matrix was estimated. The various aspects of processing a commercial cast iron during ausetmpering, the phase transformation, microstructural evolution have been examined along with the property of the material. The mechanical behaviour of the material and the scope for further improvement is discussed.     

Conserved domains in DNA repair proteins and evolution of repair systems

A detailed analysis of protein domains involved in DNA repair was performed by comparing the sequences of the repair proteins from two well-studied model organisms, the bacterium Escherichia coli and yeast Saccharomyces cerevisiae, to the entire sets of protein sequences encoded in completely sequenced genomes of bacteria, archaea and eukaryotes. Previously uncharacterized conserved domains involved in repair were identified, namely four families of nucleases and a family of eukaryotic repair proteins related to the proliferating cell nuclear antigen. In addition, a number of previously undetected occurrences of known conserved domains were detected; for example, a modified helix-hairpin-helix nucleic acid-binding domain in archaeal and eukaryotic RecA homologs. There is a limited repertoire of conserved domains, primarily ATPases and nucleases, nucleic acid-binding domains and adaptor (protein-protein interaction) domains that comprise the repair machinery in all cells, but very few of the repair proteins are represented by orthologs with conserved domain architecture across the three superkingdoms of life. Both the external environment of an organism and the internal environment of the cell, such as the chromatin superstructure in eukaryotes, seem to have a profound effect on the layout of the repair systems. Another factor that apparently has made a major contribution to the composition of the repair machinery is horizontal gene transfer, particularly the invasion of eukaryotic genomes by organellar genes, but also a number of likely transfer events between bacteria and archaea. Several additional general trends in the evolution of repair proteins were noticed; in particular, multiple, independent fusions of helicase and nuclease domains, and independent inactivation of enzymatic domains that apparently retain adaptor or regulatory functions.     

An effective hybrid approach to remote-sensing image classification

This article presents a hybrid fuzzy classifier for effective land-use/land-cover (LULC) mapping. It discusses a Bayesian method of incorporating spatial contextual information into the fuzzy noise classifier (FNC). The FNC was chosen as it detects noise using spectral information more efficiently than its fuzzy counterparts. The spatial information at the level of the second-order pixel neighbourhood was modelled using Markov random fields (MRFs). Spatial contextual information was added to the MRF using different adaptive interaction functions. These help to avoid over-smoothing at the class boundaries. The hybrid classifier was applied to advanced wide-field sensor (AWiFS) and linear imaging self-scanning sensor-III (LISS-III) images from a rural area in India. Validation was done with a LISS-IV image from the same area. The highest increase in accuracy among the adaptive functions was 4.1% and 2.1% for AWiFS and LISS-III images, respectively. The paper concludes that incorporation of spatial contextual information into the fuzzy noise classifier helps in achieving a more realistic and accurate classification of satellite images.     

Reaction kinetics of 2‐((2‐aminoethyl) amino) ethanol in aqueous and non‐aqueous solutions using the stopped‐flow technique

Observed pseudo‐first‐order rate constants (k_o) for the reaction between CO₂ and 2‐((2‐aminoethyl) amino) ethanol (AEEA) were measured using the stopped‐flow technique in an aqueous system at 298, 303, 308 and 313 K, and in non‐aqueous systems of methanol and ethanol at 293, 298, 303 and 308 K. Alkanolamine concentrations ranged from 9.93 to 80.29 mol m^?3 for the aqueous system, 29.99–88.3 mol m^?3 for methanol and 44.17–99.28 mol m^?3 for ethanol. Experimentally obtained rate constants were correlated with two mechanisms. For both the aqueous‐ and non‐aqueous‐AEEA systems, the zwitterion mechanism with a fast deprotonation step correlated the data well as assessed by the reported statistical analysis. As expected, the reaction rate of CO₂ in the aqueous‐AEEA system was found to be much faster than in methanol or ethanol. Compared to other promising amines and diamines studied using the stopped‐flow apparatus, the pseudo‐first‐order reaction rate constants were found to obey the following order: PZ (cyclic‐diamine) > EDA (diamine) > AEEA (diamine) > 3‐AP (primary amine) > MEA (primary amine) > EEA (primary amine) > MO (cyclic‐amine). The reaction rate constant of CO₂ in aqueous‐AEEA was double that in aqueous‐MEA, and the difference increased with an increase in concentration. All reaction orders were practically unity. With a higher capacity for carbon dioxide and a higher reaction rate, AEEA could have been a good substitute to MEA if not for its high thermal degradation. AEEA kinetic behaviour is still of interest as a degradation product of MEA. © 2012 Canadian Society for Chemical Engineering     

Roles of graphite oxide, clay and POSS during the combustion of polyamide 6

Two contrasting approaches have been adopted in the current study to obtain environmental benign and superior flame retardant polymer nanocomposites. In the first approach, polyhedral oligomeric silsesquioxane (POSS) is incorporated as an additional filler in polyamide 6/clay nanocomposite to improve the homogeneity of the ‘physical’ barrier, since POSS transforms to a glassy material upon fire and enhances the coupling of silicate layers to each other. In the second approach, fire response of an intumescent system, polyamide 6/graphite oxide (GO), is compared to polyamide 6/clay systems. The intention of using GO as a flame retardant is to benefit from its layered structure (‘physical’ barrier mechanism) and intumescent/blowing effect (‘chemical’ mechanism). Considerable insight and physical knowledge on the roles of different fillers in the combustion process have been obtained, which would provide useful guidance for the development of a new generation of nanocomposites. Besides the obvious contrasting differences in the flame properties of different materials, the incorporation of various fillers, depending on their nature, has both advantages and disadvantages from the viewpoint of flame retardancy.     

Cost-Sharing Mechanisms for Network Design

We consider a single-source network design problem from a game-theoretic perspective. Gupta, Kumar and Roughgarden (Proc. 35th Annual ACM STOC, pp. 365–372, 2003) developed a simple method for a single-source rent-or-buy problem that also yields the best-known approximation ratio for the problem. We show how to use a variant of this method to develop an approximately budget-balanced and group strategyproof cost-sharing method for the problem. The novelty of our approach stems from our obtaining the cost-sharing methods for the rent-or-buy problem by carefully combining cost-shares for the simpler Steiner tree problem. Our algorithm is conceptually simpler than the previous such cost-sharing method due to Pál and Tardos (Proc. 44th Annual FOCS, pp. 584–593, 2003), and improves the previously-known approximation factor of 15 to 4.6. A preliminary version of this work appears in the Proc. International Workshop on Approximation Algorithms for Combinatorial Optimization Problems, 2004. This research was done in part during the IMA Workshop on Network Management and Design at the University of Minnesota, April 2003. A. Gupta supported in part by an NSF CAREER award CCF-0448095, and by an Alfred P. Sloan Fellowship. A. Srinivasan supported in part by the National Science Foundation under Grant No. 0208005 and ITR Award CNS-0426683. Research of é. Tardos supported in part by ONR grant N00014-98-1-0589, and NSF grants CCR-0311333 and CCR-0325453.     

Data space mapping for efficient I/O in large multi-dimensional databases

In this paper, we propose data space mapping techniques for storage and retrieval in multi-dimensional databases on multi-disk architectures. We identify the important factors for an efficient multi-disk searching of multi-dimensional data and develop secondary storage organization and retrieval techniques that directly address these factors. We especially focus on high dimensional data, where none of the current approaches are effective. In contrast to the current declustering techniques, storage techniques in this paper consider both inter- and intra-disk organization of the data. The data space is first partitioned into buckets, then the buckets are declustered to multiple disks while they are clustered in each disk. The queries are executed through bucket identification techniques that locate the pages. One of the partitioning techniques we discuss is especially practical for high dimensional data, and our disk and page allocation techniques are optimal with respect to number of I/O accesses and seek times. We provide experimental results that support our claims on two real high dimensional datasets.     

The TORGO database of acoustic and articulatory speech from speakers with dysarthria

This paper describes the acquisition of a new database of dysarthric speech in terms of aligned acoustics and articulatory data. This database currently includes data from seven individuals with speech impediments caused by cerebral palsy or amyotrophic lateral sclerosis and age- and gender-matched control subjects. Each of the individuals with speech impediments are given standardized assessments of speech-motor function by a speech-language pathologist. Acoustic data is obtained by one head-mounted and one directional microphone. Articulatory data is obtained by electromagnetic articulography, which allows the measurement of the tongue and other articulators during speech, and by 3D reconstruction from binocular video sequences. The stimuli are obtained from a variety of sources including the TIMIT database, lists of identified phonetic contrasts, and assessments of speech intelligibility. This paper also includes some analysis as to how dysarthric speech differs from non-dysarthric speech according to features such as length of phonemes, and pronunciation errors.     

Evaluation of high temperature gas cleaning options for biomass gasification product gas for Solid Oxide Fuel Cells

An analysis of high temperature gas cleaning systems for cleaning the product gas of biomass gasification for fueling solid oxide fuel cells (SOFCs) is presented. Influence of biomass derived contaminants on SOFCs is briefly presented and the removal of potential contaminants such as tar, particulates, H₂S and HCl, alkali compounds from biosyngas is reviewed. It appears that the gasification product gas can be cleaned to meet the requirements of SOFCs based on Ni/GDC anodes at high temperatures (typically in the range of 1023–1223 K) by using currently known gas cleaning methods. Although information from literature, results from chemical equilibrium studies and preliminary experiments were sufficient to put forward a conceptual design for a high temperature gas cleaning system, detailed experimental investigations are still required. This is needed to obtain detailed information on contaminant tolerance of SOFCs, and to arrive at detailed designs of gas cleaning units that are economically viable for biomass gasifier-SOFC systems.     

Self-supervised role learning for graph neural networks

Knowledge and Information Systems - We present InfoMotif, a new semi-supervised, motif-regularized, learning framework over graphs. We overcome two key limitations of message passing in popular...