We report the observation of unidirectional plasmon propagation in metallic nanowires over distances >10 μm. Through control of the incident excitation wavelength and rod composition, we demonstrate the selective coupling of photons into the plasmon mode of a 20 nm diameter nanowire. This mode then propagates in a nonemissive fashion down the wire length before being emitted as an elastically scattered photon at the distal end. As expected from previous studies of plasmon excitation in nanoparticles and thin films, we observe a strong wavelength and material dependence of this phenomenon. This metal-dependent plasmon propagation is exploited to produce a wire through which plasmons propagate unidirectionally. A bimetallic wire with a sharp Au/Ag heterojunction is shown to display both wavelength dependence and unidirectionality with respect to plasmon propagation across the heterojunction. It is expected that these results will contribute to the growing interest in optical energy transport in molecular-le...

Unidirectional Plasmon Propagation in Metallic Nanowires

Neural networks

The Riemann-Liouville fractional integral for repeated fractional integration is expanded in block pulse functions to yield the block pulse operational matrices for the fractional order integration. Also, the generalized block pulse operational matrices of differentiation are derived. Based on the above results we propose a way to solve the fractional differential equations. The method is computationally attractive and applications are demonstrated through illustrative examples.

Numerical solution of fractional differential equations using the generalized block pulse operational matrix

The present work proposes a complementary pair of orthogonal triangular function (TF) sets derived from the well-known block pulse function (BPF) set. The operational matrices for integration in TF domain have been computed and their relation with the BPF domain integral operational matrix is shown. It has been established with illustration that the TF domain technique is more accurate than the BPF domain technique as far as integration is concerned, and it provides with a piecewise linear solution. As a further study, the newly proposed sets have been applied to the analysis of dynamic systems to prove the fact that it introduces less mean integral squared error (MISE) than the staircase solution obtained from BPF domain analysis, without any extra computational burden. Finally, a detailed study of the representational error has been made to estimate the upper bound of the MISE for the TF approximation of a function f ( t ) of Lebesgue measure.

A new set of orthogonal functions and its application to the analysis of dynamic systems

Solving nonlinear mixed Volterra-Fredholm integral equations with two dimensional block-pulse functions using direct method

A PC-based study has been made on conventional on-off control and its corresponding fuzzy version for a small temperature process. It is observed that fuzzy control of temperature offers smoother control than the conventional one. The fuzzy control has been effected by using one and two variables. However, it is observed that for such a process, introduction of two variables in fuzzy logic mode of control does not impart any significant improvement over its single variable counterpart. Performance of the process in different modes is elaborated with the help of relevant curves.

Studies on a PC-based Fuzzy and Non-fuzzy On-Off Controller for a Temperature Process

This paper describes a simple elegant method for determining the proper phase sequence of any balanced multiphase system. The phases of a multiphase system are correlated with natural numbers which designate the correct phase sequence. The reference phase, for instance R-phase in a three phase system, is chosen at random and is assigned the serial number 1. Then with the help of a general rule and an 8085A microprocessor, the serial number of any other phase is determined. The developed system is cheap, easy to use and foolproof. Supporting laboratory experiments corroborate these qualities.

Microprocessor based sequence identifier for balanced multiphase systems

A theoretical investigation has been made on the choice of various TM and TE cavity modes and their combinations in the perturbation method of determination of radial electron density distribution in a plasma column. The modes at S and X bands have been chosen from consideration of electric field configuration, cavity design, calculated frequency shifts for different axial electron densities and the ratios of such shifts corresponding to a pair of modes for rectangular, killian, parabolic and trapezoidal types of distribution. Further, it has been suggested that the additional cavity modes may provide more data for electron density distribution by the perturbation methods due to Hess (1964) and Burkley and Sexton (1968).

On cavity modes for determination of plasma electron distribution

A digital logic model of a gate turn-off thyristor is developed considering the turn-on and turn-off mechanisms of the device. A commonly used R-C-D snubber circuit is also included in the proposed model. Relations between different delay times, e.g. storage time, Tall time, turn-off time and tail time, become apparent from the model. The model is simulated with the help of a microprocessor to establish the validity of the proposal.

Microprocessor based simulation and digital logic model of gate turn-off thyristor

A modified variable resolution semiflash ADC, based on ?bit segmentation
 scheme?, is presented. Its speed and comparator count are identical to a
 normal flash ADC. An 8-bit ADC has 256 different bit combinations. Sixteen
 consecutive bit combinations from the MSB side - beginning with the first
 one, remain unaltered for such an ADC. It continues this way till the last
 group of sixteen bits. In the designed circuit, the four MSB and four LSB
 bits are determined in the first and second part of the clock. Following the
 same logic, the bits in a 16-bit ADC can be found out in only two clock
 cycles by employing only fifteen comparators. It implies that a higher
 resolution ADC can easily be determined with low power and small die area.
 It is tested in P-SIM Professional 9 for an 8-bit ADC and curves drawn to
 establish the validity of the proposal.

/pdf/realization-of-a-variable-resolution-modified-semiflash-adc-2sz8c407.pdf

Sunit K. Sen

Papers

Studies on a PC-based Fuzzy and Non-fuzzy On-Off Controller for a Temperature Process

Microprocessor based sequence identifier for balanced multiphase systems

On cavity modes for determination of plasma electron distribution

Microprocessor based simulation and digital logic model of gate turn-off thyristor

Realization of a variable resolution modified semiflash ADC based on bit segmentation scheme