Genetic-algorithm-based reliability optimization for computernetwork expansion

This paper explains the development and implementation of a new methodology for expanding existing computer networks. Expansion is achieved by adding new communication links and computer nodes such that reliability measures of the network are optimized within specified constraints. A genetic algorithm-based computer network expansion methodology (GANE) is developed to optimize a specified objective function (reliability measure) under a given set of network constraints. This technique is very powerful because the same approach can be extended to solve different types of problems; the only modification required is the objective function evaluation module. The versatility of the genetic algorithm is illustrated by applying it to solve various network expansion problems (optimize diameter, average distance and computer network reliability for network expansion). The results are compared with the optimal solutions computed using an exhaustive search of complete solution space. The results demonstrate that GANE is very effective (in both accuracy and computation time) and applies to a wide range of problems, but it does not guarantee the optimal results for every problem     

Low Voltage High Output Impedance Bulk-Driven Quasi-Floating Gate Self-Biased High-Swing Cascode Current Mirror

A low voltage self-biased high-swing cascode current mirror using bulk-driven quasi-floating gate MOSFET is proposed in this paper. The proposed current mirror bandwidth and especially the output impedance show a significant improvement compared to prior arts. The current mirror presented is designed using bulk-driven and bulk-driven quasi-floating gate N-channel MOS transistors, which helped it to operate at very low supply voltage of \({\pm }0.2\,\hbox {V}\). To achieve high output resistance, the current mirror uses regulated cascode stage followed by super cascode architecture. The small-signal analysis carried out proves the improvement achieved by proposed current mirror. The current mirror circuit operates well for input current ranging from 0 to \(250\,{\upmu }\mathrm{A}\) with good linearity and shows the bandwidth of 285 MHz. The input and output resistances are found as \(240\,\Omega \) and \(19.5\,\hbox {G}\Omega \), respectively. Further, the THD analysis and Monte Carlo simulations carried prove the robustness of proposed current mirror. The complete analysis is done using HSpice on UMC \(0.18\,\upmu \mathrm{m}\) technology.     

An analytical drain current model for graded channel cylindrical/surrounding gate MOSFET

In the present paper, a comprehensive drain current model incorporating various effects such as drain-induced barrier lowering (DIBL), channel length modulation and impact ionization has been developed for graded channel cylindrical/surrounding gate MOSFET (GC CGT/SGT) and the expressions for transconductance and drain conductance have been obtained. It is shown that GC design leads to drain current enhancement, reduced output conductance and improved breakdown voltage. The effectiveness of GC design was examined by comparing uniformly doped (UD) devices with GC devices of various L₁/L₂ ratios and doping concentrations and it was found that GC devices offer superior characteristics as compared to the UD devices. The results so obtained have been compared with those obtained from 3D device simulator ATLAS and are found to be in good agreement.     

Enhanced photoluminescence from CdS nanocrystals encapsulated by PVP and SHMP

The effects of the stabilizing agent on the structural and luminescence properties of cadmium sulfide (CdS) nanocrystals have been investigated. Samples were prepared by chemical precipitation method using sodium hexametaphosphate (SHMP) and polyvinyl pyrrolidone (PVP). The structural and optical properties have been studied by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) absorption, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. XRD patterns confirm the presence of cubic zinc blend crystal structure with space group F-43m. The results show the variation in crystallite size with change in surfactant. Blue shift in absorption edge as compared to bulk CdS is found. PL results represent broad and very intense red emission with smaller particle size due to modification of surface emitting states with surfactant.     

A General Space Vector PWM Algorithm for Multilevel Inverters, Including Operation in Overmodulation Range

This paper proposes a simple space vector pulsewidth modulation algorithm for a multilevel inverter for operation in the overmodulation range. The proposed scheme easily determines the location of the reference vector and calculates on-times. It uses a simple mapping to generate gating signals for the inverter. A five-level cascaded inverter is used to explain the scheme. The scheme can be easily extended to a n-level inverter. It is applicable to neutral point clamped topology as well. Experimental results are provided for five-level and seven-level cascaded inverters     

An Integer-Programming Approach to the Bicriteria Multicasting Problem in Optical Networks

We consider the problem of designing quality-of-service (QoS)-constrained routes for a set of multicast groups in an all-optical network. We present an integer goal programming formulation with the objectives of minimizing the cost of the multicast solution and minimizing the maximum link load of the network. Based on the structural properties of the problem, we develop a variable-fixing heuristic which is easy to implement, requires a modest amount of CPU time, and provides high-quality solutions. An extensive computational study is presented to justify our claims     

Distributed fair scheduling in a wireless LAN

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling, it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmissions such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.     

Analytical approach towards available bandwidth estimation in wireless ad hoc networks

Wireless Networks - Since 1999 IEEE 802.11 has become a dominating wireless technology for providing WLAN in both public and private places. The protocol has evolved with time and the current...     

A Novel FrWT Based Arrhythmia Detection in ECG Signal Using YWARA and PCA

Wireless Personal Communications - In general, Electrocardiogram (ECG) signal gets corrupted by variety of noise at the time of its acquisition. Unfortunately, these noise tend to mask the crucial...     

FGMOS transistor based low voltage and low power fully programmable Gaussian function generator

In this paper floating gate MOS (FGMOS) transistor based fully programmable Gaussian function generator (GFG) is presented. The circuit combines the exponential characteristics of MOS transistor in weak inversion, tunable property of FGMOS transistor, and its square law characteristic in strong inversion region to implement the GFG. FGMOS based squarer is the core sub circuit of GFG that helps to implement full Gaussian function for positive as well as negative half of the input voltage. FGMOS implementation of the circuit provides low voltage operation, low power consumption, reduces the circuit complexity and increases the tunability of the circuit. The performance of circuit is verified at 0.75 V in TSMC 0.18 μm CMOS, BSIM3 and level 49 technology by using Cadence Spectre simulator. To ensure robustness of the proposed GFG, simulation results for various process corner variations have also been included.