Kinetics of the Hydrolysis of some alkyl halides in aqueous ethyl alcohol

A comparison of the rates of substitution and elimination reactions occuring simultaneously in alkaline hydrolysis of n-amyl chloride, isoamyl chloride, n-amyl iodide and n-hexyl iodide at different temperatures and in varying alcohol-water mixtures, has been made. Under the same conditions the rates of solvolysis of these halides have also been reported. In the case of n-amyl halides there is a much larger rate difference between chloride and bromide than between bromide and iodide.     

Design methodologies for high-performance noise-tolerant XOR-XNOR circuits

Scaling down to deep submicrometer (DSM) technology has made noise a metric of equal importance as compared to power, speed, and area. Smaller feature size, lower supply voltage, and higher frequency are some of the characteristics for DSM circuits that make them more vulnerable to noise. New designs and circuit techniques are required in order to achieve robustness in presence of noise. Novel methodologies for designing energy-efficient noise-tolerant exclusive-OR-exclusive- NOR circuits that can operate at low-supply voltages with good signal integrity and driving capability are proposed. The circuits designed, after applying the proposed methodologies, are characterized and compared with previously published circuits for reliability, speed and energy efficiency. To test the driving capability of the proposed circuits, they are embedded in an existing 5-2 compressor design. The average noise threshold energy (ANTE) is used for quantifying the noise immunity of the proposed circuits. Simulation results show that, compared with the best available circuit in literature, the proposed circuits exhibit better noise-immunity, lower power-delay product (PDP) and good driving capability. All of the proposed circuits prove to be faster and successfully work at all ranges of supply voltage starting from 3.3 V down to 0.6 V. The savings in the PDP range from 94% to 21% for the given supply voltage range respectively and the average improvement in the ANTE is 2.67X.     

Analytical modeling of subthreshold current and subthreshold swing of Gaussiandoped strained-Si-on-insulator MOSFETs

This paper presents the analytical modeling of subthreshold current and subthreshold swing of short- channel fully-depleted （FD） strained-Si-on-insulator （SSOI） MOSFETs having vertical Gaussian-like doping pro- file in the channel. The subthreshold current and subthreshold swing have been derived using the parabolic approx- imation method. In addition to the effect of strain on silicon layer, various other device parameters such as channel length （L）, gate-oxide thickness （tox）, strained-Si channel thickness （ts_Si）, peak doping concentration （Np）, project range （Rp） and straggle （op） of the Gaussian profile have been considered while predicting the device characteris- tics. The present work may help to overcome the degradation in subthreshold characteristics with strain engineering. These subthreshold current and swing models provide valuable information for strained-Si MOSFET design. Ac- curacy of the proposed models is verified using the commercially available ATLASTM, a two-dimensional （2D） device simulator from SILVACO.     

Low-power adaptive filter architectures and their application to51.84 Mb/s ATM-LAN

We present low-power and high-speed algorithms and architectures for complex adaptive filters. These architectures have been derived via the application of algebraic and algorithm transformations. The strength reduction transformation is applied at the algorithmic level as opposed to the traditional application at the architectural level. This results in a power reduction by 21% as compared with the traditional cross-coupled structure. A fine-grained pipelined architecture for the strength-reduced algorithm is then developed via the relaxed lookahead transformation. This technique, which is an approximation of the conventional lookahead computation, maintains the functionality of the algorithm rather than the input-output behavior. Convergence analysis of the proposed architecture is presented and supported via simulation results. The pipelined architecture allows high-speed operation with negligible hardware overhead. It also enables an additional power savings of 39 to 69% when combined with power-supply reduction. Thus, an overall power reduction ranging from 60-90% over the traditional cross-coupled architecture is achieved. The proposed architecture is then employed as a receive equalizer in a communication system for a data rate of 51.84 Mb/s over 100 m of UTP-3 wiring in an ATM-LAN environment. Simulation results indicate that speedups of up to 156 can be achieved with about a 0.8-dB loss in performance     

Analog Circuit Fault Detection Using Location of Poles

A method for detection of parametric faults occurring in linear analog circuits based on location of poles of the Circuit Under Test (CUT) is proposed. In the proposed method, the value of each component of the CUT is varied within its tolerance limit using monte carlo simulation. The upper and lower bounds of magnitude, phase angle, real part and imaginary part of all poles of the CUT are obtained. While testing, the locations of poles are obtained. If any one or more of the poles lies outside the tolerance limit then the CUT is declared faulty. The effectiveness of the proposed method is validated through two benchmark circuits like second order sallenkey band pass filter and fourth order leapfrog low pass filter.     

Fabry-Perot optical intensity modulator at 1.3 mu m in silicon

A new type of all-silicon surface-normal optical intensity modulator at 1.3 mu m is reported. It can be easily butt-coupled with a cleaved single-mode fiber. The device utilizes free-carrier effects in silicon to achieve phase modulation and a built-in Fabry-Perot cavity to convert the phase modulation into intensity modulation. A 10% modulation depth with a driving current density as low as 6*10/sup 3/ A/cm/sup 2/ was demonstrated. Because it can be easily coupled with single-mode fiber, and at the same time it is compatible with silicon technology, this device can provide an interface between silicon electronic circuitry and fiber optics in applications such as the fiber-to-home return link where system cost is a deciding figure.<>     

Comparison of two stochastic models for two-unit series system with cold standbys

Reliability characteristics are compared for two stochastic models of a system that has two non-identical units, arranged in series, each unit with its identical cold standby. The same set of assumptions is used for both models, except that in model 2 both of the standby units replace the failed operative unit instantaneously whereas in model 1 an operative failed unit is replaced by its corresponding standby unit (i.e. only one unit is replaced in this case). A single repair facility is available to repair the failed unit. Failure and repair time distributions are assumed to be negative exponential.     

Reliability analysis of a two-unit cold standby redundant system with two operating modes

This paper considers a two unit cold standby redundant system subject to a single repair facility with exponential failure and general repair time distribution. Each unit can work in three different modes — normal, partial failure and total failure. There is a perfect switch to operate the standby unit on total failure of the operative unit. The system has been analysed to determine the reliability parameters e.g. mean time to system failure (MTSF), steady state availability, mean recurrence to a state and expected number of visits to a state, first two moments of time in transient state, by using the theory of Semi-Markov Process. Howard's reward structure has been super-imposed on the Semi-Markov Process to obtained expected profit of the system. A number of results obtained earlier are derived as particular cases.     

Effect of Colloidal Silver on Optical Transmittance Characteristics of Bulk Cadmium Zinc Telluride Crystals

Colloidal silver is observed to affect the transmittance of p-type Cd_1−y Zn _y Te (CZT) single-crystal substrate material at room temperature. The optical transmittance spectra have been analyzed in the near-infrared (NIR) and mid-infrared (MIR) regions. The transmittance characteristics of CZT showed significant reduction in absorption due to split-off valance band transitions in the NIR region and intervalence band absorption in the MIR region upon coating CZT substrates with silver paste. This reduction in absorption has been explained to be due to the compensation of the acceptor defects (native and foreign). Silver atoms incorporated from the silver coating help in compensation of these defects. A similar effect on transmittance characteristics of mercury cadmium telluride (MCT) epilayers grown on CZT substrates after coating silver paste on the CZT substrate side was also observed. An improvement in the transmittance of CZT substrates after the application of silver paste was observed. A similar improvement in transmittance is usually achieved by annealing the substrates in a Cd/Zn atmosphere. The results are explained by considering the formation of neutral complexes of acceptors (cadmium vacancies) and the interstitial silver. This study also points to the important conclusion that silver paste on CZT should be applied with caution for measurement purposes since it diffuses even at room temperature and modifies the optical characteristics.