Wavelet transform image coding using lattice vector quantisation

A novel method for the efficient coding of image wavelet coefficients using zerotree multistage lattice vector quantisation is presented. This method achieves high compression ratios with good picture quality, maintaining a very simple implementation. Simulation results demonstrate that the coding performance of this algorithm favourably compares to some of the best reported image compression results     

Block classification for an adaptive 1-D/2-D DCT video coding

A classification scheme for an adaptive one- or two-dimensional discrete cosine transform (1-D/2-D DCT) technique is described and demonstrated to be a more appropriate strategy than the conventional 2-D DCT for coding motion compensated prediction error images. Two block-based classification methods are introduced and their accuracy in predicting the correct transform type discussed. The accuracy is assessed with a classification measure designed to ascertain the effectiveness of energy compaction when the predicted transform class is applied; vis-a-vis horizontally, vertically or two-dimensionally transformed blocks. Energy compaction is a useful property not only for efficient entropy coding but also for enhancing the resilience of the transform coder to quantisation noise. Improvements against the homogeneous 2-D DCT system both in terms of the peak signal to noise ratio and subjective assessments are achieved. Observable ringing artifacts along edges, which are usual in conventional transform coding, are reduced     

Analysis of a Micro-Optomechatronic Force Sensor

Abstract

The purpose of this article is to study the dynamic behavior and modal analysis of a micro-optomechatronic device with primary applications to force sensing and optical attenuation/coupling. The system consists of two initially aligned micro-cantilevers with a narrow gap between them. The light beam enters to the first waveguide and, after propagation along it, couples to second waveguide through the mentioned narrow gap. The externally static or dynamic applied force on the first micro-cantilever deflects it and results in reduced optical coupling between the two waveguides. Changes in this factor are measured to give the properties of the applied force.     

Synthesis of CuInS2 nanoparticles via simple microwave approach and investigation of their behavior in solar cell

Copper indium sulfide, CuInS₂, nanocrystals were synthesized by a new precursor complex, [bis(2-hyroxyacetophenato)copper(ΙΙ)], [Cu(HAP)₂], via a microwave method. The effects of sulfur sources, solvents, heating time and microwave power on morphology of product were investigated. The as-synthesized CuInS₂ nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) spectroscopy, and room temperature photoluminescence (PL) spectroscopy. The nanoparticles of CuInS₂ were used to prepare CuInS₂ film by doctor's blade technique. The fill factor (FF), open circuit voltage (V_oc), and short circuit current (I_sc) were obtained by I–V characterization.     

Synthesis and characterization of CuInS2 microsphere under controlled reaction conditions and its application in low-cost solar cells

CuInS₂ microspheres were synthesized by Ultrasonic method in propylene glycol as solvent and copper oxalate, indium chloride and thioacetamde (TAA) as precursors. Optimum conditions such as reaction time, solvent type, sulfur source, and ultrasonic power were determined. Then, a thin film of CuInS₂ was prepared and its application in solar cells was investigated. Photovoltaic characteristics such as V_oc, J_sc and FF were measured. X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy were performed to characterize the CuInS₂ microsphere. The optical band gap of the CuInS₂ microsphere was estimated to be 2.28 eV.     

A new cost function for improving Anypath routing performance of VANETs in highways

Wireless Networks - Instability of wireless networks and high mobility of vehicles make effective and reliable delivery of packets in VANETs a challenging issue. Anypath routing is proposed to...     

On the achievable rate bounds in multi-pair massive antenna relaying with correlated antennas

Wireless Networks - The issue of antenna correlation in multi-pair massive antenna relay network is studied. Under the spatial correlation properties of the channel, an analytical approximation for...     

Studying thin film damping in a micro-beam resonator based on non-classical theories

In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamped micro-beam bound between two fixed layers. The micro-gap between the micro-beam and fixed layers is filled with air. As classical theories are not properly capable of pre-dicting the size dependence behaviors of the micro-beam, and also behavior of micro-scale fluid media, hence in the presented model, equation of motion governing longitudinal displacement of the micro-beam has been extracted based on non-local elasticity theory. Furthermore, the fluid field has been modeled based on micro-polar theory. These coupled equations have been simplified using Newton-Laplace and continuity equations. After transforming to non-dimensional form and linearizing, the equations have been discretized and solved simultaneously using a Galerkin-based reduced order model. Considering slip boundary conditions and applying a complex frequency approach, the equivalent damping ratio and quality factor of the micro-beam resonator have been obtained. The obtained values for the quality factor have been compared to those based on classical theories. We have shown that applying non-classical theories underestimate the values of the quality factor obtained based on classical theo-ries. The effects of geometrical parameters of the micro-beam and micro-scale fluid field on the quality factor of the res-onator have also been investigated.     

List coloring of graphs having cycles of length divisible by a given number

Let G be a graph and χ_l(G) denote the list chromatic number of G. In this paper we prove that for every graph G for which the length of each cycle is divisible by l (l≥3), χ_l(G)≤3.     

Solitary wave solutions to the Tzitzeica type equations obtained by a new efficient approach

The properties of Tzitzeica equations in nonlinear optics have received a great attention of many recent studies. In this work, the so-called generalized exponential rational function method (GERFM) has been applied for finding the analytical solution of two nonlinear partial differential equations type of equations, namely Tzitzeica-Dodd-Bullough and Tzitzeica equation. The proposed method provides a wide range of closed-form travelling solutions leading to a very effective and simply-applied method by means of a symbolic computation system. The method not only provides a general form of solutions with some free parameters but also shows potential application to other types of nonlinear partial differential equations.