Power-area evaluation of various double-gate RF mixer topologies

In this letter, we analyze the suitability of the double gate MOSFETs (DG MOSFETs) for RF-mixer applications from the point of optimizing the transconductance gain, power consumption, and area. Mixer topologies using the 0.13-/spl mu/m conventional MOSFETs, simultaneously driven DG MOSFETs (SDDG) and the independently driven DG MOSFETs (IDDG) are compared using extensive device simulations. In the frequency range 1-40 GHz, our simulation results show that the mixer circuits realized using the SDDG technologies show an order of magnitude lower power-area product, for a given transconductance gain, compared to the conventional and the IDDG technologies.     

Geographic random forwarding (GeRaF) for ad hoc and sensor networks: multihop performance

In this paper, we propose a novel forwarding technique based on geographical location of the nodes involved and random selection of the relaying node via contention among receivers. We focus on the multihop performance of such a solution, in terms of the average number of hops to reach a destination as a function of the distance and of the average number of available neighbors. An idealized scheme (in which the best relay node is always chosen) is discussed and its performance is evaluated by means of both simulation and analytical techniques. A practical scheme to select one of the best relays is shown to achieve performance very close to that of the ideal case. Some discussion about design issues for practical implementation is also given.     

The Method of Angular Line to Calculate Eigenvalues for Microstrip Antennas

The method of angular line (MAL) is presented for calculating the resonant frequency of microstrip antenna, which is available in other literature and originally used to analyze various waveguide structure. The results obtained by using this method are in conformity with those reported elsewhere.     

Grafting of glycidylmethacrylate onto demineralized xenogeneic bone in aqueous medium

Summary Demineralized xenogeneic bone (DXB) was prepared from bovine cortical tibia and graft copolymerized with glycidylmethacrylate (GMA) using a combination of potassium persulfate (K₂S₂0₈) and sodium metabisulfite (Na₂S₂O₅)as redox initiating system in aqueous medium. To optimize the reaction condition, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and thereafter decrease in most of the cases. The optimum temperature and time were found to be 40°C and 180 minutes, respectively. The grafting results have been discussed and a reaction mechanism is proposed. Functional groups and structural changes of the graft copolymer were determined by Fourier transform infrared (FT-IR) spectroscopic method for proof of grafting and the results are discussed. Received: 12 August 2002/Revised version: 30 October 2002/ Accepted: 25 November 2002 Correspondence to R. Murugan     

Effect of Covers for Soil and Water Conservation Using Tilting Flume

The effect of stone and vegetative covers was evaluated for soil and water conservation in a waterway on alfisols. Experiments were conducted on a hydraulic tilting flume under simulated flow (93 and 40 cm2?s?1) and slope (0.1, 1.0, 3.0, and 5.0%) conditions. The depth of soil was maintained at 0.35 m over a perforated bed to facilitate deep drainage. A comparative study of bare soil, stone cover (50%), and vegetative cover (50%) is made to evaluate soil loss, deep drainage, Manning’s roughness coefficient, and the Froude number. The study has revealed that stone cover is more effective than vegetative cover at lower discharge in reducing the flow velocity, and thereby soil erosion. Deep drainage has been reduced from lower to higher discharge for all the slopes with cover measures, including bare soil. It is found that cover measures are necessary beyond 3% slope in order to prevent rill erosion in alfisols.     

Type, extent and use of colours in ready-to-eat (RTE) foods prepared in the non-industrial sector – a case study from Hyderabad, India

The type and extent of colours added to ready‐to‐eat (RTE) foods prepared in the non‐industrial sector of India was investigated. Of the 545 RTE foods analysed, 90% contained permitted colours, 2% contained a combination of permitted and non‐permitted colours and 8% contained only non‐permitted colours. However in RTE foods with permitted colours, 73% exceeded 100 ppm, as prescribed by the Prevention of Food Adulteration Act of India, and 27% were within the prescribed levels. Among the permitted colours, tartrazine was the most widely used colour followed by sunset yellow. The maximum concentration of colours was detected in sweet meats (18 767 ppm), non‐alcoholic beverages (9450 ppm), miscellaneous foods (6106 ppm) and hard‐boiled sugar confectioneries (3811 ppm). Among the non‐permitted colours found, rhodamine was most commonly used. Some of the foods, such as savouries and miscellaneous foods like sugar coated aniseed and almond milk, are not supposed to contain colours as per the Prevention of Food Adulteration Act, but were found to contain colours.     

VLSI parallel architecture for Kalman filterAn algorithm specific approach

An algorithm specific architecture for Kalman filter is presented. It is based on systolic arrays. Parallelism has been exploited on both algorithm and architecture levels. Faddeev's algorithm has been employed. The involved computation tasks, triangularization and nullification are performed in parallel which leads to a speedup of about 40%. Throughput has been increased by using bi-trapezoidal arrays. Techniques have been employed for data storage and skewing which enables fast data transfer rates. A VLSI implementation of a prototype of matrix of size 4×4 has been discussed.     

27Al-NMR studies of aluminum transport across yeast cell membranes

Aluminum (Al) transport across yeast cells was studied using Dy(NO3)3 as a shift reagent by 27Al-NMR spectroscopy. The results showed that (a) Al enters the yeast cells at 15 min and over a period of time, within 4 h, an equilibrium sets in between outside and inside Al; (b) citrate does not favor Al going into the yeast cells at pH 5.0; and (c) EDTA brings out all the Al that has entered the yeast cells.