SOLVENT EXTRACTION OF PAKISTAN COALS (III) EXTRACTION AND CHARACTERIZATION OF THE EXTRACTS BY SPECTROSCOPIC TECHNIQUES

The Makerwal coal of Pakistan gives higher extractibi1ity with Tetrahydrofuran ( THF ) as compared to Sharigh, Sor-Range and Lakhra coals. The structural characterization of Pakistan coal extracts by FT-IR spectroscopy indicates that all the extracts contained less condensed aromatic rings in comparision to their original coal.     

Association of aortic aneurysm in patients with systemic lupus erythematosus: a series of case reports and a review of the literature

Systemic lupus erythematosus associated aortic aneurysm with or without dissection is an uncommon manifestation of the disease, but it exists and can be a grave complication. We describe 3 patients and compare them to others in the literature. Controlling hypertension and using steroid sparing agents where possible may help in preventing this complication.     

Optical properties of Ge1-yCy alloys

The Ge_1-yC_y semiconductor alloy system offers promise as a material for use in heterostructure devices based on Si as well as other materials. We have grown Ge_1-y C_y alloys by solid source molecular beam epitaxy on Si substrates. Layer thicknesses ranged from 0.01 to 3 μm, and Auger electron spectroscopy and secondary ion mass spectrometry indicated C fractions up to 3 at. %. Optical absorption in the near-infrared region indicated a shift in the energy bandgap from that of Ge which was attributed to the effects of alloying. The dependence of the bandgap on composition was consistent with linear interpolations of the Ge and C conduction band minimums. We observed a fundamental absorption edge characteristic of an indirect bandgap material. Photoluminescence spectra at 11K of thick, relaxed layers indicated single broad peaks near the expected bandgap energy.     

Determination of activation temperature of glass bulb sprinklers using a thermal liquid bath

A thermal liquid bath was used to determine the activation temperature of a wide range of temperature rated (57–182°C) glass bulb (3 and 5 mm diameters) sprinklers using water and glycerine. An optical switch and a thermocouple were installed adjacent to each sprinkler (within 10 mm) to record the activation of each glass bulb in the liquid bath having a uniform temperature distribution (±0.5°C). All the tests for determining the activation temperatures of glass bulb sprinklers were conducted in the liquid bath using a 0.277°C/min rate of temperature rise. Based on a heat transfer analysis, this rate is within the maximum allowable rate of rise of water and glycerine temperatures, which allows the glass bulb temperature to closely follow the liquid temperature. The sprinkler activation temperature was evaluated in terms of percentage rating, which is expressed as the percent variation of the average activation temperature, as measured in the liquid bath, from the nominal rated temperature. Sprinklers (93°C rated or lower) activation temperatures in water were consistently within ±3.5% of rating. In glycerine, the activation temperatures of sprinklers rated between 93 and 182°C performed within 3.5% of their rating. Copyright © 2005 John Wiley & Sons, Ltd.     

Velocity-image model for online signature verification.

In general, online signature capturing devices provide outputs in the form of shape and velocity signals. In the past, strokes have been extracted while tracking velocity signal minimas. However, the resulting strokes are larger and complicated in shape and thus make the subsequent job of generating a discriminative template difficult. We propose a new stroke-based algorithm that splits velocity signal into various bands. Based on these bands, strokes are extracted which are smaller and more simpler in nature. Training of our proposed system revealed that low- and high-velocity bands of the signal are unstable, whereas the medium-velocity band can be used for discrimination purposes. Euclidean distances of strokes extracted on the basis of medium velocity band are used for verification purpose. The experiments conducted show improvement in discriminative capability of the proposed stroke-based system.     

Dry etching of GaN using chemically assisted Ion beam etching with HCI and H2/Cl2

The dry etching characteristics of GaN were investigated using chemically assisted ion beam etching (CAIBE) with HCI and H₂/Cl₂ gas. Etch rates using CAIBE/HC1 were investigated as a function of Ar ion beam energy and substrate temperature. These results were compared to CAIBE/C1₂. Etch rates were also investigated for CAIBE/H₂/Cl₂ for various ratios of H₂:C1₂. Highly anisotropic submicron lines are demonstrated using CAIBE/HC1. Auger electron spectroscopy was used to investigate surface stoichiometric changes of samples etched with CAIBE/HC1, CAIBE/H₂/Cl₂,, and CAIBE/C1₂. The diffusion of deuterium into GaN during etching was also investigated using secondary ion mass spectrometry.     

Scheduling and allocation in high-level synthesis using stochastic techniques

High-level synthesis is the process of automatically translating abstract behavioral models of digital systems to implementable hardware. Operation scheduling and hardware allocation are the two most important phases in the synthesis of circuits from behavioral specification. Scheduling and allocation can be formulated as an optimization problem. In this work, a unique approach to scheduling and allocation problem using the genetic algorithm (GA) is described. This approach is different from a previous attempt using GA (Wehn et al., IFIP Working Conference on Logic and Architecture Synthesis, Paris, 1990, pp. 47–56) in many respects. The main contributions include: (1) a new chromosomal representation for scheduling and for two subproblems of allocation; and (2) two novel crossover operators to generate legal schedules. In addition the application of tabu search (TS) to scheduling and allocation is also implemented and studied. Two implementations of TS are reported and compared. Both genetic scheduling and allocation (GSA) and tabu scheduling and allocation (TSA) have been tested on various benchmarks and results obtained for data-oriented control-data flow graphs are compared with other implementations in the literature. (A discussion on GSA was presented at the European Design Automation Conference Euro-DAC'94 in Grenoble, France, and TSA at the International Conference on Electronics, Circuits and Systems — ICECS'94 in Cairo, Egypt.) A novel interconnect optimization technique using the GA is also realized.