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The present work discusses about the mechanical and metallurgical properties of Incoloy 800 H friction welded joints. The process parameters namely friction pressure, friction time, upsetting pressure, upset time, and rotational speeds were varied from low level to high level to study their effects on the properties of the weldments. The tensile tests were carried out at four different temperatures namely at room temperature, 550, 650, and 750 °C. From the results, it is observed that as the testing temperature increased, there was a reduction in tensile strength of welds. The friction welds had higher hardness than the base metals. This was due to the formation of secondary phases (γ′ and M23C6) in friction welds. The tensile and impact fracture surfaces were further analyzed through SEM and finally the individual effects of the parameters with respect to the microstructures variation in the welds were studied.
Observations of flare emissions in the optical continuum are very rare. Therefore, the analysis of such observations is useful and may contribute to our understanding of the flaring chromosphere and photosphere. We study the white light continuum emission observed during the X6.9 flare. This emission comes not only from the flare ribbons but also form the nearby plage area. The main aim of this work is to disentangle the flare and plage (facula) emission. We analyzed the spatial, spectral and temporal evolution of the flare and plage properties by analyzing multi-wavelength observations. We study the morphological correlation of the white-light continuum emission observed with different instruments. We found that some active region areas which produce the continuum emission correspond rather to plages than to the flare kernels. We showed that in some cases the continuum emission from the WL flare kernels is very similar to the continuum emission of faculae.
We explore the temporal evolution of flare plasma parameters including temperature (T) - differential emission measure (DEM) relationship by analyzing high spectral and temporal cadence of X-ray emission in 1.6-8.0 keV energy band, recorded by SphinX (Polish) and Solar X-ray Spectrometer (SOXS; Indian) instruments, during a B8.3 flare which occurred on July 04, 2009. SphinX records X-ray emission in 1.2-15.0 keV energy band with the temporal and spectral cadence as good as 6 μs and 0.4 keV, respectively. On the other hand, SOXS provides X-ray observations in 4-25 keV energy band with the temporal and spectral resolution of 3 s and 0.7 keV, respectively. We derive the thermal plasma parameters during impulsive phase of the flare employing well-established Withbroe-Sylwester DEM inversion algorithm.
The mixing promoting capability of right-angled triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the exit of a Mach 2 axi-symmetric nozzle. The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and marginally favourable pressure gradients at the nozzle exit. It was found that, at all levels of expansion of the present study though the core length reduction caused by both the tabs are appreciable, but the mixing caused by the truncated tab is superior. The mixing promoting efficiency of the truncated tab is found to increase with increase of nozzle pressure ratio (that is, decrease of adverse pressure gradient). For all the nozzle pressure ratios of the present study, the core length reduction caused by the truncated vertex tab is more than that of sharp vertex tab. As high as 84% reduction in core length is achieved with truncated vertex right-angled triangular tabs at moderately overexpanded level, corresponding to expansion level pe/pa = 0·90. The corresponding core length reduction for right-angled triangular tabs with sharp vertex and rectangular tabs are 65% and 31%, respectively. The present results clearly show that the mixing promoting capability of the triangular tab is best than that of rectangular tabs at identical blockage and flow conditions.
This paper describes the spatial and temporal investigation of laser ablated plasma plume of cerium oxide target using Langmuir probe. Cerium oxide target was ablated using a KrF (λ ~ 248 nm) gas laser. Experimental studies confirmed that oxygen partial pressure of 2 × 10−2 mbar is sufficient enough to get good quality films of cerium oxide. At this pressure, plume was diagnosed for their spatial and temporal behavior. Spatial distribution was investigated at a distance of 15 mm, 30 mm, and up to a maximum distance of 45 mm from the target, whereas temporal behavior has been recorded in the range of 0 to 50 µS with an interval of 0.5 µS. The average electron densities are found to be maximum at 30 mm from the target position and the plasma current of the laser ablated ceria is found to be maximum at 22 µS.
An experimental study has been carried out to understand jet flow development from plain and grooved rectangular nozzles of aspect ratio 2:1 using two-component hotwire anemometry. Grooves of square configuration (side 4mm) and length 5mm were introduced in the (i) minor-axis, (ii) major-axis and, (iii) in both minor- and major-axes directions. The equivalent diameter of the plain rectangular nozzle is 37·5mm. Studies were carried out for a nominal jet exit velocity of 20ms−1 and for Reynolds number based on equivalent diameter of 54,000. The introduction of grooves in either plane does not show any influence on the potential-core length but results in faster jet-decay thereafter. It is observed that the grooves when introduced in minor-axis direction inhibit the jet growth in that plane while promoting the jet growth along major-axis plane and hence, delays the phenomena of axis-switching. However when introduced in major-axis direction, the grooves promote jet growth along major-axis plane while inhibiting jet-growth in minor-axis plane. Cross-sectional contours of mean-velocity suggest that the grooves modify the process of overall jet development significantly in the plane in which they are introduced relative to the plain jet and hence, significantly affect the axis-switching location in each case.
Constitute hypothesis for origin of supernumerary phantom limb (SPL) after stroke.
Single case description, review of literature and formulation of hypothesis.
A 59-year-old lady was evaluated for complaints of left-sided hemiparesis and extra limbs attached to her left shoulder for the past 7 months. Neuropsychological assessment revealed left hemineglect with SPL, and profile suggested bilateral frontal, right parietotemporal and basal ganglia involvement. Magnetic resonance imaging brain scan showed gliotic cavity secondary to the old haematoma in right putamen with white matter changes in the right frontoparietotemporal lobes.
The conceptual framework of body schema can be used to classify many of the neurological disorders of body representation. Generation of SPL comes under the subtype of pathology of updating among the disorders of body schema. The continuous updating allows the body schema to modulate perceptual processing of objects according to their position in space. Brain areas classified as parts of motor system can, under pathological conditions (haemorrhage), influence body perception. So, when she used to move her arm, the representation of the estimated position was not updated by the motor commands. Sensory and motor information therefore becomes discrepant, and failure to integrate these two sources of information leads to loss of normal coherence, and the perceived shape of the body was altered by adding a SPL to accommodate the discrepancy.
The purpose of this research was to probe nanotube-polymer composites for evidences of radiation induced chemistry at the interface of the host polymer and the nanotube structures. Single wall carbon nanotube (SWNT) / poly (methyl methacrylate) (PMMA) composites were fabricated and exposed to gamma radiation with a Co60 source at a dose rate of 1.28 X 106 rad/hour in an air environment for a total dose of 5.9 Mrads. Neat nanotube paper and neat PMMA were also exposed. Spun coat films of SWNT/PMMA were exposed to gamma radiation with a Ce157at a dose rate of 4.46 x 103 rad/hr for a total dose of 3.86 Mrads. Both irradiated and non-irradiated samples were compared. Glass transition temperatures were characterized by differential scanning calorimetry. Dynamic mechanical analysis and dielectric analysis evidenced changes in relaxations induced by irradiation. Irradiated composites exhibited radiation induced chemistry distinct from degradation effects noted in the pure polymer. Scanning electron microscopy provided images of the SWNTs and SWNT/PMMA interface before and after irradiation. This investigation imparts insight into the nature of radiation induced events in nanotubes and nanocomposites.
Global and Regional Characteristics and Impacts of ENSO Variability
Martin P. Hoerling, National Oceanic and Atmospheric Administration, Oceanic and Atmospheric Research, Climate Diagnostics Center, Boulder, Colorado 80303, U.S.A.,
Arun Kumar, National Oceanic and Atmospheric Administration, National Centers for Environmental Prediction, Environmental Modelling Center, Camp Springs, Maryland 20746, U.S.A.
It is now well established that the El Niño/Southern Oscillation (ENSO) impacts the climate of middle and high latitudes. Unanswered questions remain, however, and their resolution is central to assessing and fully harvesting the atmospheric predictability inherent in the ENSO phenomenon. Among these questions are the sensitivity of the extratropical response to the annual cycle, the nonlinearity of that response with respect to the sign and amplitude of tropical sea surface temperature (SST) anomalies, and the further sensitivity of the response to differences in the SST anomaly patterns that distinguish one El Niño event from another. Beyond these problems of seasonal to interannual variability, it is also important to understand multidecadal-scale variations of ENSO impacts and to assess their origins.
Our inquiry into these problems begins with an analysis of the last half-century of observed circulation data, using the upper tropospheric flow patterns to identify the teleconnections that link the tropics and the extratropics during ENSO. Several new aspects of the observed teleconnection behavior are highlighted; however, the data archive is undoubtedly too brief to offer a complete or even an accurate sample of the spectrum of atmospheric sensitivity to ENSO. Nor is it likely that the full spectrum of tropical SST variations themselves have been sampled by observations. We thus provide additional analyses based on the results of atmospheric general circulation model experiments that have been forced either with the recent 50-year record of observed global SST variations or with idealized SST anomalies.
The relative stability of standard extended dislocation dipoles and some new stable defects with lozenge-shaped cross sections have been numerically estimated. An earlier study of these defects in an isotropic fee structure has been extended to the anisotropic case to assess the effect of anisotropy on the calculations. The study is further extended to the case of the L12 crystal structure of the ordered alloy Ni3Al, where the Burgers vectors are large. Results indicate that the introduction of anisotropy has a small effect in determining the relative stability of extended dislocation faults. The results also show that the large values of the Burgers vectors stabilize the arrays in Ni3Al and that the most stable defect favored is the screw lozenge array LD.
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