Solving general multi-class closed queuing networks using parametric decomposition

This paper presents a new approach to evaluate the performance of general multi-class closed queuing networks. The approach uses parametric characterization of the traffic processes to derive two-moment approximations for performance measures at individual nodes. Based on these approximations, linkage equations are derived to establish the relationships between the various nodes in the network. These relationships result in a system of non-linear equations that is solved using an iterative procedure. Numerical studies comparing the performance of the approach with detailed simulations suggest that the approach yields fairly accurate estimates of performance measures without significant computational complexity.     

Turn-off operation of a MOS-gate 2.6 kV 4H–SiC gate turn-off thyristor

The turn-off operation of a 4H–SiC gate turn-off thyristor (GTO) with 2.6 kV breakover voltage has been investigated using an external Si-MOSFET as a gate-to-emitter shunt (MOS-gate mode), in the temperature interval 293–496 K. The maximum cathode current density j_cmax that can be turned off in such a mode decreases from 1850 A/cm² at 400 K to 700 A/cm² at 496 K. The room temperature j_cmax value is estimated to be about 3700 A/cm². The above j_cmax values are essentially higher than those observed when turning this thyristor off in the conventional GTO mode. Turn-off transients in the MOS-gate mode have been studied in both quasi-static and pulse regimes. Temperature dependencies of the turn-on and turn-off times, as well as those of the turn-on and turn-off energy losses have been measured. The upper switching frequency of the GTO is estimated to be about 700 kHz.     

Development of magnetorheological fluid-based process for finishing of ferromagnetic cylindrical workpiece

A magnetorheological fluid-based process is developed for the internal surface finishing of ferromagnetic cylindrical workpiece. The existing finishing processes based on magnetorheological fluid are not equipped to finish the internal ferromagnetic cylindrical surface significantly as it obtained higher magnetic flux density than the MR polishing fluid. At present, magnetorheological fluid-based finishing tools are designed to ensure the maximum magnetic flux density always present on the outer finishing tool core surface as compared to internal surface of ferromagnetic cylindrical workpiece surface. To validate this present principal idea, the magnetostatic finite element analysis has been performed on the newly designed finishing tools. The preliminary experiments have also been conducted to evaluate the finishing performance with the two newly designed finishing tools. The percentage reduction in surface roughness (R_a) values with I-shaped tool core is found as 65–78% after 150 min of finishing, whereas, with rectangular shaped tool core is found as 78–81% after 90 min of finishing. The results clearly revealed that the present finishing tool with rectangular shaped core is more suitable for uniform significant finishing of ferromagnetic cylindrical internal workpiece than the I-shaped core. The developed process can be useful in finishing of cylindrical mold and dies, hydraulic cylinder, barrel for injection molding, etc.     

The backward masking red light effect in schizophrenia: Relationship to clinical features and neurocognitive performance.

The “backward masking red light effect” involves a change in visual backward masking performance with a red (compared with a green or gray) background that is in the opposite direction relative to nonpsychiatric controls. This effect has been previously reported in individuals with schizophrenia, their first-degree relatives, and a schizotypy sample. The current study provides the first examination of the relationship of this effect with clinical and neurocognitive measures in a new sample of higher functioning patients with schizophrenia. A location backward masking by pattern task was administered to 16 outpatients with schizophrenia and 21 nonpsychiatric controls. The task was presented on red, green, and gray backgrounds. There was a significant group by color interaction at the 60-ms stimulus onset asynchrony: Participants with schizophrenia tended to decrease accuracy with a red (compared with a gray) background, whereas controls tended to increase accuracy. This interaction remained significant after covarying for baseline (gray) backward masking accuracy. In the schizophrenia patients, a decrease in backward masking accuracy to the red background was correlated with more negative symptoms, lower estimated premorbid IQ, and greater color–word Stroop interference but was not related to positive or disorganized symptoms, age of onset, duration of illness, digit symbol coding performance, or baseline (gray) backward masking accuracy. In contrast, there was no relationship between the red light change score and any of the neurocognitive variables in the control group. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Thermal decomposition of Co-Al layered double hydroxide: Identification of precursor to oxide with spinel structure

The layered double hydroxide (LDH) of Co with Al decomposes to yield an oxide residue with the spinel structure below 250°C. The decomposition reaction is preceded by the formation of an intermediate hydroxide in which the metal hydroxide layers are regularly stacked about the c-crystallographic axis, but the layers themselves are aperiodic. Aperiodicity is modeled by locating randomly chosen Co²⁺ ions in tetrahedral sites in the interlayer region. This phase is characterized by a single strong basal reflection in its powder diffraction pattern. All other reflections are extinguished on account of (i) turbostratic disorder which destroys all hkl reflections and (ii) layer aperiodicity, which destroys all two dimensional hk reflections. Given its topochemical relationship with the spinel structure, such an intermediate is a necessary precursor to spinel formation.     

2D graphene supported nickel oxide nano-composite for fiber optic ethanol gas sensing,removal of azo dye,and biological activity

Journal of Materials Science: Materials in Electronics - Green synthesis of multifunctional metal oxide nanoparticles and its composites are widely evaluated for their efficacy in environmental and...     

A Size‐Selective Intracellular Delivery Platform

Identifying and separating a subpopulation of cells from a heterogeneous mixture are essential elements of biological research. Current approaches require detailed knowledge of unique cell surface properties of the target cell population. A method is described that exploits size differences of cells to facilitate selective intracellular delivery using a high throughput microfluidic device. Cells traversing a constriction within this device undergo a transient disruption of the cell membrane that allows for cytoplasmic delivery of cargo. Unique constriction widths allow for optimization of delivery to cells of different sizes. For example, a 4 μm wide constriction is effective for delivery of cargo to primary human T‐cells that have an average diameter of 6.7 μm. In contrast, a 6 or 7 μm wide constriction is best for large pancreatic cancer cell lines BxPc3 (10.8 μm) and PANC‐1 (12.3 μm). These small differences in cell diameter are sufficient to allow for selective delivery of cargo to pancreatic cancer cells within a heterogeneous mixture containing T‐cells. The application of this approach is demonstrated by selectively delivering dextran‐conjugated fluorophores to circulating tumor cells in patient blood allowing for their subsequent isolation and genomic characterization.     

Probing a Device's Active Atoms

Materials science and device studies have, when implemented jointly as “operando” studies, better revealed the causal link between the properties of the device's materials and its operation, with applications ranging from gas sensing to information and energy technologies. Here, as a further step that maximizes this causal link, the paper focuses on the electronic properties of those atoms that drive a device's operation by using it to read out the materials property. It is demonstrated how this method can reveal insight into the operation of a macroscale, industrial‐grade microelectronic device on the atomic level. A magnetic tunnel junction's (MTJ's) current, which involves charge transport across different atomic species and interfaces, is measured while these atoms absorb soft X‐rays with synchrotron‐grade brilliance. X‐ray absorption is found to affect magnetotransport when the photon energy and linear polarization are tuned to excite Fe? O bonds parallel to the MTJ's interfaces. This explicit link between the device's spintronic performance and these Fe? O bonds, although predicted, challenges conventional wisdom on their detrimental spintronic impact. The technique opens interdisciplinary possibilities to directly probe the role of different atomic species on device operation, and shall considerably simplify the materials science iterations within device research.     

Software Standards for the Multicore Era

Systems architects commonly use multiple cores to improve system performance. Unfortunately, multicore hardware is evolving faster than software technologies. New multicore software standards are necessary in light of the new challenges and capabilities that embedded multicore systems provide. The newly released Multicore Communications API standard targets small-footprint, highly efficient intercore and interchip communications.     

Covariation in subskin‐bulk temperature difference with environmental parameters in the north Indian Ocean

This study aims to explore the dependence of the ocean subskin–bulk temperature difference ΔT (T _subskin?T _2.5m) on environmental parameters over the north Indian Ocean. This was possible because of the fortuitous concurrence of two parallel programmes, viz., the Tropical Rainfall Measuring Mission (TRMM) carrying a Microwave Imager (TMI) and the Indian moored buoy programme, over 6 years (1998–2003). The environmental parameters considered in this study are total water vapour (TWV), cloud liquid water content (CLW), sea surface wind speed, bulk temperature (T _2.5m) and T _2.5m?T _air temperature difference, consisting of a composite data matrix of more than 3000 sets. The study revealed absence of any perceptible dependence on TWV and CLW. For T _2.5m between 24°C and 28°C, the mean Δ T is a decreasing function of T _2.5m. Data classification indicates that most of the cases of T _2.5m<28°C belong to Bay of Bengal during December to February. For the T _2.5m>28°C, Δ T is very small. Our results on the variation of Δ T with T _2.5m?T _air are linear and in opposite phase. The daytime Δ T variation over the north Indian Ocean displays a decreasing trend with increasing wind. The night‐time Δ T pattern, especially over the Bay of Bengal, is found to be very unusual: it remains insensitive to the variations in wind speed, and it is predominantly positive. Diurnal variation of Δ T under wind speed below 6 m s^?1 is studied for overall data set as well as for the individual season data set. The low wind cases reproduce onset of warming at 9 h local time and a peak around 15 h local time. The average maximum amplitude of Δ T is more than 0.34°C with a standard deviation of greater than 0.7°C. Diurnal warming during pre‐monsoon (post‐monsoon) is highest (lowest).