Thermal and FTIR spectral studies in various proportions of urea thiourea mixed crystal

Mixed crystals of various proportions of urea thiourea were grown by slow evaporation of aqueous solution at room temperature. The bright and transparent crystals obtained were characterized using thermogravimetry–differential thermal analysis (TG–DTA) and FTIR spectroscopic analyses. A fitting decomposition pattern for the title compound was formulated on the TG curve which shows a two-stage mass loss between 175 and 750 °C. In this temperature range, DTA curves show exothermic peaks supporting the formulated decomposition pattern. The FTIR spectra show the characteristic absorption, vibration frequencies due to urea thiourea. Detailed structural analysis of the compound is under progress.     

FDTD based transition time dependent crosstalk analysis for coupled RLC interconnects

The performance of high density chips operating in the GHz range is mostly affected by on-chip interconnects. The interconnect delay depends on many factors, a few of them are inputs toggling patterns, line ＆ coupling parasitics, input rise/fall time and source/load characteristics. The transition time of the input is of prime importance in high speed circuits. This paper addresses the FDTD based analysis of transition time effects on functional and dynamic crosstalk. The analysis is carried out for equal and unequal transition times of coupled inputs. The analysis of the effects of unequal rise time is equally important because practically, it is quite common to have mismatching in the rise time of the signals transmitting through different length wires. To demonstrate the effects, two distributed RLC lines coupled inductively and capacitively are taken into consideration. The FDTD technique is used because it gives accurate results and carries time domain analysis of coupled lines. The number of lumps in SPICE simulations is considered the same as those of spatial segments. To validate the FDTD computed results, SPICE simulations are run and results are compared. A good agreement of the computed results has been observed with respect to SPICE simulated results. An average error of less than 3.2% is observed in the computation of the performance parameters using the proposed method.     

Empirical process approach to some two-sample problems based on ranked set samples

We study the asymptotic properties of both the horizontal and vertical shift functions based on independent ranked set samples drawn from continuous distributions. Several tests derived from these shift processes are developed. We show that by using balanced ranked set samples with bigger set sizes, one can decrease the width of the confidence band and hence increase the power of these tests. These theoretical findings are validated through small-scale simulation studies. An application of the proposed techniques to a cancer mortality data set is also provided. Part of the research was conducted while Kaushik Ghosh was visiting Statistical Research and Applications Branch of the National Cancer Institute on an Intergovernmental Personnel Assignment.     

An interactive method for multiple-objective mathematical programming problems

An interactive method is developed for solving the general nonlinear multiple objective mathematical programming problems. The method asks the decision maker to provide partial information (local tradeoff ratios) about his utility (preference) function at each iteration. Using the information, the method generates an efficient solution and presents it to the decision maker. In so doing, the best compromise solution is sought in a finite number of iterations. This method differs from the existing feasible direction methods in that (i) it allows the decision maker to consider only efficient solutions throughout, (ii) the requirement of line search is optional, and (iii) it solves the problems with linear objective functions and linear utility function in one iteration. Using various problems selected from the literature, five line search variations of the method are tested and compared to one another. The nonexisting decision maker is simulated using three different recognition levels, and their impact on the method is also investigated.     

A Differential CMOS Current-Mode Variable Gain Amplifier with Digital dB-Linear Gain Control

A novel CMOS variable gain amplifier operating on current signals with a dB-linear gain control is presented. The gain control is achieved by multiplying a digitally synthesized exponentially varying control current signal by a differential input signal in the current domain. A current amplifier at the output sets the gain to the desired level. Current-mode operation allows for a reduced supply voltage by minimizing the voltage swing at the low impedance nodes of the circuit. Multiple circuit realizations for various blocks are presented allowing for designs meeting different constraints. Experimental realization of the variable gain amplifier shows the validity of the presented approach.     

Oxynitride gate dielectric grown in nitric oxide (NO): the effectof reoxidation on dielectric reliability of the active edge

Reoxidation of an oxynitride gate dielectric grown by NO anneal of thermal oxide has been studied. This process has demonstrated ~3-5X improvement of Q_BD of active edge intensive capacitors in comparison to thermal oxide, N₂O and NO oxynitride. This improvement is believed to be due to the reduction of local thinning of the gate dielectric at the field oxide edge which also reduces local build-up of positive charge near the gate electrode at the isolation edges     

Enhancement of self focusing of laser beams in a degenerate magnetoactive solid state plasma

This paper presents an investigation of the enhancement of self focusing of high frequency EM waves in a compensated degenerate magnetoactive solid state plasma. The nonlinearity in the dielectric constant responsible for self focusing arises due to nonuniform heating and consequent redistribution Of carriers. A rigorous kinetic treatment valid beyond the perturbation limit has been presented assuming the carrier relaxation time to be energy dependent. The results show that the self-focusing of extraordinary waves is enhanced while that of ordinary waves is reduced with $\text{ω}{}_{\mathrm{c}}\text{ω}$ increasing. However the focusing of extraordinary waves is not possible when ω_c > ω. The effect of degeneracy is also found to enhance the self-focusing of the waves while that of the enhanced absorption is to suppress the self-focusing process.     

Colchiceine as an extractive indicator in the determination of copper(II)

Colchiceine, a new extractive indicator, is satisfactorily used in the determination of copper(II). A highly sensitive greenish yellow complex is formed with copper, which is extractable into chloroform. The results are comparable in sensitivity and selectivity with those of its precursors.     

Identification of mixed states using electron spectroscopy

X-ray photoelectron spectroscopy (XPS) is a highly surface sensitive technique and is used in identification of oxidation states in catalysts at various stages. Copper, silver and platinum based catalysts are widely used in petrochemical industries. Our attempts at characterization have revealed that elements in these catalysts are normally present then one stae. It is terefore essential to identify their in more chemical as well as oxidation states. Such identification combined with quantitative analysis of data is helpful in correlating catalyst performance. Examples of mixed state identification are presented.IPCL Communication No. 266