Creep deformation of induction pressure welded 2·25Cr-1Mo steel

In this paper, experimental results involving the effect of stress and temperature on creep behaviour of induction pressure welded (IPW) 2·25Cr-1Mo steel are presented. Creep rupture tests were conducted at 550–700°C in steps of 50°C over a stress range of 112·5–180 MPa. Above 650°C failure of the specimen was enhanced due to the microstructural instability. Failure in the specimens occurred invariably in the heat affected zones (HAZ), and the fracture surfaces indicated ductile failure.     

DARYN-a distributed decision-making algorithm for railway networks:modeling and simulation

The state of the art in scheduling “point-to-point” trains in a railway network utilizes the principles of centralized decision-making. The major difficulty of this approach is that the execution time and the memory requirements increase nonlinearly as the system grows in size. The present paper introduces a new approach, “DARYN”, wherein the overall decision process is analyzed and distributed onto every natural entity of the system. In DARYN, the decision process for every train is executed by an on-board processor that negotiates, dynamically and progressively, for temporary ownership of the tracks with the respective station controlling the tracks, through explicit processor to processor communication primitives. This processor then computes its own route utilizing the results of its negotiation, its knowledge of the track layout of the entire system, and its evaluation of the cost function. Every station's decision process is also executed by a dedicated processor that, in addition, maintains absolute control over a given set of tracks and participates in the negotiation with the trains. Presently, DARYN utilizes a simple cost function. However, if one chooses to increase the complexity of the cost function, DARYN's advantage over the traditional approach increases due to its enormous available computational power. Given that the current microprocessors such as MC68030, MC88000, Intel 486, and Intel 860 are powerful yet relatively inexpensive, a network of concurrently executing processors may offer superior price-performance quotient over a single high performance computer     

Eddy current probe sensitivity as a function of coil construction parameters

We report the results of the first phase of a study designed to quantify the relationship between eddy current coil construction and the performance of these coils used in nondestructive evaluation (NDE) inspections. The ferrite core coils wound for this study are small but typical of the sizes commonly used in commercially manufactured eddy current probes. Coil diameters range from 1 mm to 7 mm with lengths from 0.5 mm to 4 mm. Seven parameters were studied and included ferrite diameter, ferrite permeability, coil aspect ratio, number of turns, distance of the windings from the inspection end of the ferrite, wire gauge, and length of the ferrite beyond the end of the windings. Additionally, the coil set was designed to provide some indication of the repeatability of identical constructions, what we have called winding inhomogeneity. The coils were incorporated into surface probes for scanning defects in flat plate specimens. The measure of sensitivity was the change of probe impedance (Z) as the probe was scanned from an unflawed area to the flawed area of the test specimen. Measurements were also made of the component of Z perpendicular to the liftoff vector.The data reported here were produced from a set of 27 probes scanned over a single defect. The defect was an electrical-discharge-machined (EDM) notch in a 19 mm thick 7075-T6 aluminum alloy specimen. The part-circular EDM notch was 9 mm long and 3 mm deep and 0.1 mm wide.Analysis of the data shows that the number of turns, the winding distance, the coil aspect ratio, and the backside ferrite length all affect the coil sensitivity. Winding inhomogeneity is significant for coils having many winding layers and can be considerably larger than the contribution made by variations in some of the construction factors. Wire gauge, ferrite diameter, and permeability showed no significant effects on our measure of sensitivity in this study.     

Structural health monitoring of railway tracks using IoT-based multi-robot system

Neural Computing and Applications - A multi-robot-based fault detection system for railway tracks is proposed to eliminate manual human visual inspection. A hardware prototype is designed to...     

Preparation of high-purity antimony by electrodeposition

Detailed studies were carried out on the electrowinning of antimony from SbCl₃–HCl–H₂SO₄ and SbCl₃–HCl baths using a graphite anode and a tantalum cathode, the anode being enclosed in a cylindrical glass compartment provided with a sintered disc. Disintegration of the graphite anode increased with increase in anode current density and duration of electrolysis. Analysis of gas evolved at the anode indicated that the presence of sulphuric acid increased the production of CO₂. The anodic disintegration was reduced to a negligibly low value by circulation of 6m HCl through the anode compartment. Optimum conditions were determined for electrowinning of antimony from a SbCl₃–HCl bath. The tantalum content in the metal was 0.1–0.2 p.p.m.     

Hydrogen permeation during zinc-manganese alloy plating

Electrodeposition of metals from solution is usually accompanied by the simultaneous discharge of hydrogen ions or water molecules. When hydrogen is liberated at an iron/steel surface during electrodeposition, a portion of the hydrogen is absorbed by the metal surface and then diffuses into the interior. The diffused hydrogen produces some detrimental effects, such as reduction in ductility and loss in mechanical strength, leading to hydrogen embrittlement. The present paper reports investigations on hydrogen permeation measurements in zinc-manganese alloy deposition using a modified electrode clamp for easy removal and fixing of the electrode. Hydrogen permeation studies indicate that the porosity of the deposit increases in the following order:Zn-Mn(14.3%), Zn-Mn(2.4%), Zn-Mn(24.8%) and Zn-Mn(37.5%).This is in agreement with the corrosion data obtained which indicates that Zn-Mn alloy deposits with low manganese content show better performance than pure zinc deposits.     

Fabricating Strong and Stiff Bioplastics from Whole Spirulina Cells

Since the 1950s, 8.3 billion tonnes (Bt) of virgin plastics have been produced, of which around 5 Bt have accumulated as waste in oceans and other natural environments, posing severe threats to entire ecosystems. The need for sustainable bio-based alternatives to traditional petroleum-derived plastics is evident. Bioplastics produced from unprocessed biological materials have thus far suffered from heterogeneous and non-cohesive morphologies, which lead to weak mechanical properties and lack of processability, hindering their industrial integration. Here, a fast, simple, and scalable process is presented to transform raw microalgae into a self-bonded, recyclable, and backyard-compostable bioplastic with attractive mechanical properties surpassing those of other biobased plastics such as thermoplastic starch. Upon hot-pressing, the abundant and photosynthetic algae spirulina forms cohesive bioplastics with flexural modulus and strength in the range 3–5 GPa and 25.5–57 MPa, respectively, depending on pre-processing conditions and the addition of nanofillers. The machinability of these bioplastics, along with self-extinguishing properties, make them promising candidates for consumer plastics. Mechanical recycling and fast biodegradation in soil are demonstrated as end-of-life options. Finally, the environmental impacts are discussed in terms of global warming potential, highlighting the benefits of using a carbon-negative feedstock such as spirulina to fabricate plastics.     

Experimental deformation analysis of an adhesively bonded multi-material joint for marine applications

The strength and deformation of full-scale adhesively bonded multi-material joints is studied in this paper. Four joints with a thick layer of methyl methacrylate adhesive (MMA) have been manufactured in shipyard conditions. In two specimens, cracks have been introduced at steel–adhesive and composite–adhesive interfaces. One cracked and one un-cracked specimen were subjected to quasi-static tensile testing; the two remaining specimens were stepwise loaded/unloaded with increasing load until failure. The strain in the adhesive layers was measured with digital image correlation (DIC). This showed a predominant shear deformation and dissimilar shear strain patterns for different bond lines. Fibre Bragg (FBG) sensors were used to monitor strains at steel and composite constituents and to detect the onset and evolution of damage in the un-cracked specimen. Strains measured by FBG sensors correspond well with DIC results at nearby regions. All specimens failed by delamination of the composite panel near the composite–adhesive interface.     

Parallelization of a dynamic SVD clustering algorithm and its application in information retrieval

We describe an implementation of a parallel document clustering scheme based on latent semantic indexing, which uses singular value decomposition. Given a set of documents, the clustering algorithm is dynamic in the sense that it automatically infers the number of clusters to be output. The parallel version has been implemented on a LAN and on a dual‐core system. Experimental evaluation of the algorithm shows an average speed‐up of 6.22 for the LAN implementation and an average speed‐up of 3.71 for the dual‐core implementation, while still maintaining a precision and recall in the range [0.85, 1]. To put these implementations in the context of information retrieval, we use the parallel clustering algorithm and develop a document similarity search system. The similarity search system shows good performance in terms of precision and recall. Copyright © 2010 John Wiley & Sons, Ltd.