Profit evaluation of a two unit cold standby redundant system with two operating modes

This paper considers a two unit cold standby system subject to a single repair facility with exponential failure time and arbitrary repair time distribution. Each unit has three modes—normal (N), partial (P) and total failure (F). By using the regenerative point technique the system has been analysed to determine mean time to system failure and profit earned by the system. A numerical example is used to highlight the important results.     

High performance InP JFETs grown by MOCVD using tertiarybutylphosphine

Indium phosphide channel junction field effect transistors were fabricated by metalorganic chemical vapor deposition using tertiarybulylphosphine (TBP) as the alternative source for phosphine. At growth temperatures of 600°C, InP with specular surface morphology and mobilities as high as 61000 cm₂/V s at 77Khas been achieved using trimethylindium and TBP. To improve device isolation, pinch-off characteristics, and output transconductance, we employ a high resistivity (1 × 10⁸ Ω-cm) semi-insulating InP buffer layer using ferrocene as the Fe-dopant. Devices with gate lengths of 1 urn exhibit very high extrinsic transconductance of 130 mS/mm, gate-drain breakdown voltage exceeding 20 V, maximum current density of >450 mA/mm with record high f_T and f_max of 15 GHz and 35 GHz, respectively. These results indicate: that InP JFETs are promising electronic devices for microwave power amplification, and that TBP is capable of device quality materials.     

Some new results in thermomechanical processing of microalloyed steels

In recent times, efforts have been directed towards a better understanding of the mechanisms associated with deformation and restoration of austenite during continuous multipass hot rolling of microalloyed steels. The correspondence between the condition of austenite before transformation and the resultant microstructure upon cooling holds the key to the attainment of interesting properties. In the present paper, some results obtained on the deformation of austenite in a microalloyed steel, using a hot compression machine, are presented. Here, the idea was to simulate actual plate rolling or hot strip rolling conditions and study the evolution of microstructure at different stages of the hot deformation process i.e. after precise reductions at given strain rate and temperature of deformation. The paper further discusses recent results obtained by us on the influence of hot deformation parameters (strain, finish rolling temperature, temperature of deformation) and cooling rates (air cooling, spray water cooling) on the microstructure of microalloyed steel. The precise conditions leading to the evolution of acicular ferrite and bainitic microstructures have been identified. New information on the influence of short tempering treatments (15 min at 550, 600 and 650°C) on the microstructure and properties of a microalloyed steel are also outlined.     

Hadron shower energy and direction measurements using drift chambers

We report energy and angle resolutions for hadron showers produced in the CCFR iron target-calorimeter. The measurements were made using drift chambers instrumented with FADC readout; showers were produced using a momentum-analyzed hadron test beam from the Fermilab Tevatron at energies of 40, 70, 100, 150, and 200 GeV. Shower energy measurements are compared to measurements using scintillation counters in the same target.     

Vascular clogging, mononuclear cell margination, and enhanced vascular permeability in the pathogenesis of human cerebral malaria

To document histopathologic evidence on the pathogenic mechanism of human cerebral malaria, we used light microscopy to study brain specimens from 23 patients who died of central nervous system involvement with Plasmodium falciparum. Sequestration of parasitized red blood cells (PRBCs) leading to cerebral capillary clogging was seen. In a few specimens, vascular clogging by PRBCs was associated with margination of mononuclear cells. In others, capillaries were virtually empty and lymphocytes and monocytes were seen in apposition (marginated) to the capillary endothelial surface. The endothelial cells appeared plump, hypertrophied, and prominent. The capillary wall appeared thickened by fibrinous material. Massive intercellular brain edema along with extravasated red blood cells, mononuclear cells, and plasmatic fluid was also noticed. In addition to hypoxia induced by PRBC-mediated vascular clogging, marginating mononuclear cells may contribute to the pathogenesis of cerebral malaria. The precise role played by this phenomenon needs further evaluation.     

Neural network-based CAD model for the design of square-patchantennas

An artificial neural network (ANN) has been developed and tested for square-patch antenna design. It transforms the data containing the dielectric constant (ϵ_r), thickness of the substrate (h), and antenna's dominant-mode resonant frequency (f_r) to the patch length (l)     

Photoluminescence of gold-doped (Zn,Cd)S mixed phosphors

(Zn, Cd)S: Au, Cl mixed phosphors were prepared in nitrogen atmosphere with various concentrations of impurities. Photoluminescence (PL) spectra were obtained. The peak of the PL spectrum shifts towards longer-wavelength values with increasing replacement of zinc by cadmium in the host lattice. The PL efficiency was found to decrease with increasing. CdS content whereas lattice constants increased with increasing CdS concentration.     

Time dependent analysis of an ion-implanted GaAs OPFET

A time-dependent analysis of the electrical characteristics of an ion implanted GaAs optical field effect transistor (OPFET) has been carried out. Both the cases of light turning on and off at a reference time t=0 have been considered. The photovoltaic effect across the Schottky junction and the depletion width modulation in the active layer have been taken into account. The threshold voltage, channel charge, channel conductance, drain-source current, transconductance, and gate-source capacitance of the device under light turning on and off conditions have been evaluated. When light is turned on, all the parameters increase with time before reaching the steady-state value and when light is turned off, these parameters decrease with time and reach their respective values corresponding to dark condition. The time under on condition is less than that under off condition     

Effect of cerebral hypoxia on NMDA receptor binding characteristics after treatment with 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) in newborn piglets

Thymic carcinoma is a rare malignant neoplasm of the thymic epithelium, distinguished from invasive thymoma by the presence of malignant cytology and a greater incidence of local invasion and embolic metastases. Some common features of thymic carcinomas include (a) large and highly aggressive anterior mediastinal mass; (b) areas of necrosis, hemorrhage, calcification, or cyst formation; (c) gross invasion of contiguous mediastinal structures and wide spread to involve distant intrathoracic sites; (d) high incidence of extrathoracic metastases; (e) broad age range, with an average of 46 years; (f) very low incidence of paraneoplastic syndromes; and (g) very poor prognosis. Three case reports are presented, followed by an overview of the disease with emphasis on the radiographic features.