Compression Testing of Ti-6Al-4V in the Temperature Range of 303-873K

Compression testing of Ti-6Al-4V alloy has been carried out at temperatures between 303 K to 873 K. To prevent embrittlement due to atmospheric oxygen and nitrogen, the samples were given a glass coating, which also acts as a lubricant simultaneously. Dynamic Strain Aging was observed to occur in the temperature range of 600 K to 800 K. Below 600 K stresses were high. Warm working has to be done above 800 K but below 1163 K (0.6 T_m where T_m = 1940 K) which is the recrystallization temperature. Based on these conclusions, warm extrusion has been successfully carried out in the Materials Forming Laboratory of I.I.T., Madras, Chennai, India.     

Influence of scattering and two-photon absorption on the optical loss in GaAs-Al/sub 2/O/sub 3/ nonlinear waveguides measured using femtosecond pulses

The influence of scattering and two-photon absorption on the optical loss in GaAs-Al/sub 2/O/sub 3/ semiconductor nonlinear waveguides has been studied using femtosecond pulses. By deploying a scattering technique, loss coefficients were evaluated over an extended wavelength range of 1.3-2.1 /spl mu/m in the near-infrared. A systematic study involving intensity and wavelength dependence of the loss revealed the presence of two-photon absorption for wavelengths below 1.6 /spl mu/m. A simple nonlinear transmission study enabled the separation of the two-photon absorption coefficient from scattering and linear absorption. The calculated two-photon absorption coefficients were /spl sim/9-20 cm/GW.     

Synthesis,Structural, and Magnetic Properties of Nanocrystalline Ti 0.95Co0.05O2-Diluted Magnetic Semiconductors

With a view to investigate the influence of nanometric size on the structural, surface, and magnetic properties of nanocrystalline Ti_0.95Co_0.05O₂-diluted magnetic semiconductors, prepared by a novel simple controllable peroxide-assisted reflux chemical route followed by annealing at different temperatures, a systematic investigation has been undertaken. Structural characterizations such as X-ray diffraction followed by Rietveld refinement, electron diffraction pattern, Fourier transform infrared, Raman scattering, and X-ray photoelectron spectroscopy (XPS) measurements have shown anatase phase formation in nanocrystalline Ti_0.95Co_0.05O₂ without any additional impurity phases. The modified reflux chemical route was effective in obtaining pure phase Ti_0.95Co_0.05O₂ nanoparticles. Surface morphological investigations by using transmission electron microscopy and atomic force microscopy measurements showed the predominant effect of random distribution of nanoparticles on the aggregation behavior and local microstructural changes. The deconvoluted XPS core level Co 2p spectral study manifested the oxidation state of Co as + 2 and is found to be stable with varying particle size and annealing temperature. The ferromagnetic behavior was investigated by vibrating sample magnetometer, magnetic force microscopy, and electron spin resonance measurements. These magnetization studies showed all the samples are ferromagnetic at room temperature without any magnetic clusters. The correlation between structure, surface condition of the nanoparticles and local electronic interactions, and magnetization of the samples was analyzed and explored the origin of ferromagnetism.     

Synthesis and characterisation of CuS nanomaterials using hydrothermal route

Copper sulphide (CuS) nanomaterials with interesting morphology were synthesised using copper nitrate trihydrate, thiourea and water as a solvent by a simple hydrothermal route. A systematic investigation was carried out to investigate the effect of reaction time (5, 16 and 24?h) at 150°C on the morphology of the materials. Without the use of any template or additives, shape controlled synthesis of CuS nanocrystallites were achieved. The possible mechanism for the formation of the various nanostructures of CuS in this system is discussed. The prepared materials were characterised by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and DRS-UV–Vis absorption analysis. The UV–Vis spectrum shows that it is the promising material which can absorb in the visible region and hence could be used for photocatalytic applications. In addition, the electrochemical characteristic of the synthesised material was investigated by cyclic voltammetric analysis, which shows that CuS could be used for electrocatalytic applications.     

An information supply chain system view for managing rare infectious diseases: The need to improve timeliness

Timely reporting of rare infectious disease cases to the public health system, especially after identification at laboratories, is essential to initiate quick and effective public health response. To ensure that the public health reporting system is appropriately monitoring the rare infectious diseases under surveillance, it is recommended to have a regular assessment of timeliness, especially after the rare infectious case is confirmed. This study aimed to evaluate the timeliness of data reported to the Ohio Disease Reporting System (ODRS), a public health reporting system in Ohio, for managing rare infectious diseases. In a cross-sectional analysis of rare infectious disease reporting data in four local health jurisdictions (LHJs) in the state of Ohio, wide delays were found between various reporting steps, particularly when the laboratories were not using the electronic method of reporting, and the delay observed was mainly at the hospital level and at the LHJ level. This study highlights the supply chain nature of information transfer and calculates the delay at various interacting points of the information supply chain system. The results establish that a centralized approach with an electronic disease reporting system conveys information faster than traditional reporting channels (decentralized approach). Delays of the decentralized approach are isolated at various stakeholder levels and with respect to various types of rare infectious diseases for better understanding of the information supply chain system for managing rare infectious diseases.     

Flexible amorphous‐silicon non‐volatile memory

Abstract— The development of a flexible, rewritable, non‐volatile memory (NVM) that is implemented on a standard, low‐temperature a‐Si:H process without additional mask steps is reported. This NVM is a part of a flexible‐display system. Each NVM cell is composed of differentially configured thin‐film‐transistors (TFTs). The cell reads out one of two stable states depending on the relative threshold voltages of the differentially configured TFTs. Information is stored in each cell by increasing the threshold voltage of one differential TFT or the other, utilizing the well‐known electrical‐stress degradation intrinsic to a‐Si:H TFTs. The stored information is retained indefinitely with no applied power. A test array of individually addressable NVM cells has been successfully fabricated and tested on flexible stainless‐steel substrates. Read and write operation, as well as preliminary reliability measurements, are described. The design is readily scalable to large memory arrays.     

Optimisation of cold and warm workability of commercially pure titanium using dynamic materials model (DMM) instability maps

The deformation characteristics of commercially pure titanium under compression in the temperature range from 303 K to 573 K (30–300 °C) and at strain rates 0.07 s⁻¹, 0.11 s⁻¹, 8.5 s⁻¹ and 32 s⁻¹ have been studied with the view to characterising the flow instabilities occurring in the microstructure and to optimising the cold and warm workability using dynamic material model (DMM) instability maps. Conventional industrial machines such as hydraulic press, friction screw press and eccentric press are used to achieve the above strain rates. In the regime of investigated temperature and strain rate this material exhibits adiabatic shear deformation, dynamic strain ageing and flow localisation. The DMM stability criteria are used to identify the stable regime for ‘safe’ processing of the materials. DMM stability criteria predict a narrow triangular region in the temperature range from 548 K to 573 K (275–300 °C) and strain rate range from 10⁻² s⁻¹ to 10⁻¹ s⁻¹ as a stable region for deformation, which is the “optimal” domain for mechanical working of commercially pure titanium. Further, the DMM stability parameters obtained using the data generated from the tests conducted in constant true strain rate machine are also used to optimise the optimal domain to study the influence of machines on arriving at optimal domains using DMM methodology. It has been observed that the predictions of the DMM instability maps generated using the data obtained from conventional machines and constant strain rate servo-hydraulic machine are identical. The validity of this approach has also been demonstrated with forging and rolling trials at industrial scale.     

Coal washing scenario in India and future prospects

International Journal of Coal Science & Technology - Coal Washing Exploration in India dates back to 1900s; though, first coking coal washeries in India were installed after independence. At...     

Design,Development, Analysis and Comparison of Instrumented Irradiation Capsule for Online Determination of Uniaxial Creep Behavior in Structural Specimen Out-of-Pile Test Results with Analytical Results in FBTR

The main intent of this work is to develop an instrumented capsule for online determination of uniaxial creep behavior of SS 316L structural specimen. The irradiation capsule has three different zones located one over the other. In the bottom zone of the capsule, the specimen is located, with one end fixed to the bottom portion of capsule and the other end connected to a central tube through a connecting plug. In the top zone a linear variable differential transducer (LVDT) is placed and its core is passed through the central tube. The end point of the LVDT core touches the plug connected to the specimen to measure the elongation of the structural specimen. In this capsule setup, bellows are used to apply a load on the structural specimen with the use of pressurized argon gas. With the application of pressure, the bottom bellow will expand and the top bellow will get compressed. During this expansion of the bottom bellow, tensile load will be applied on the specimen, and the elongation of the structural specimen will be measured by the movement of the core of the LVDT. This paper discusses the details of the design, assembly of an out-of-pile version of instrumented capsule and its experimental results are compared with literature results. The creep experiments have been carried out at three different temperatures and three different stresses (269 MPa at 450 °C, 287 MPa at 500 °C and 306 MPa at 550 °C). Initially the capsule is filled with pre-pressurized argon gas at 6 MPa at room temperature. We have observed that the force/load due to argon gas pressure is the major component for the tensile loading of the specimen and 95% of the total load acts on the SS 316L specimen and remaining 5% load only acts on the bellow. Design concept of instrumented capsule for uniaxial creep measurement has been validated.