Optimizing Multimedia Experience in a Thin Client Environment for a Resource Constrained Processor

In this paper, we study how TCP and UDP flows interact with each other when the end system is a CPU resource constrained thin client. The problem addressed is twofold, 1) the throughput of TCP flows degrades severely in the presence of heavily loaded UDP flows 2) fairness and minimum QoS requirements of UDP are not maintained. First, we identify the factors affecting the TCP throughput by providing an in-depth analysis of end to end delay and packet loss variations. The results obtained from the first part leads us to our second contribution. We propose and study the use of an algorithm that ensures fairness across flows. The algorithm improves the performance of TCP flows in the presence of multiple UDP flows admitted under an admission algorithm and maintains the minimum QoS requirements of the UDP flows. The advantage of the algorithm is that it requires no changes to TCP/IP stack and control is achieved through receiver window control.

Modeling the Field Emission Current Fluctuation in Carbon Nanotube Thin Films

Owing to their distinct properties, carbon nanotubes (CNTs) have emerged as promising candidate for field emission devices. It has been found experimentally that the results related to the field emission performance show variability. The design of an efficient field emitting device requires the analysis of the variabilities with a systematic and multiphysics based modeling approach. In this paper, we develop a model of randomly oriented CNTs in a thin film by coupling the field emission phenomena, the electron-phonon transport and the mechanics of single isolated CNT. A computational scheme is developed by which the states of CNTs are updated in time incremental manner. The device current is calculated by using Fowler-Nordheim equation for field emission to study the performance at the device scale.

Effect of nanoparticle dispersion on glass transition in thin films of polymer nanocomposites

We present spectroscopic ellipsometry measurements on thin films of polymer nanocomposites consisting of gold nanoparticles embedded in poly(styrene). The temperature dependence of thickness variation is used to estimate the glass transition temperature, T(g). In these thin films we find a significant dependence of T(g) on the nature of dispersion of the embedded nanoparticles. Our work thus highlights the crucial role played by the particle polymer interface morphology in determining the glass transition in particular and thermo-mechanical properties of such nanocomposite films.

Ethanol sensing using CuO/MWNT thin film

Copper (II) oxide (CuO)/multiwall carbon nanotube (MWNT) thin film based ethanol-sensors were fabricated by dispersing CVD-prepared MWNTs in varying concentration over DC magnetron sputtered-CuO films. The responses of these sensors as a function of MWNT concentrations and temperatures were measured, and compared. The sensing response was the maximum at an operating temperature near 400 degrees C for all the samples irrespective of the MWNTs dispersed over them. At optimum operating temperature (T(opt)) of 407 +/- 1 degrees C, the response is linear for 100-700 ppm range and tends to saturate at higher concentrations. In comparison with bare CuO sample, the response of CuO/MWNT sensing films increased up to 50% in the linear range. The response improvement for 2500 ppm of ethanol was up to 90% compared to bare CuO sample. In addition, the sensing response time also reduced to around 23% for lowest ethanol concentration at T(opt). However, a decrease in the sensor response was observed on films with very high concentrations of MWNTs. (C) 2011 Elsevier B.V. All rights reserved.

The effect of electrochemical lithiation on physicochemical properties of RF-sputtered Sn thin films

Thin films of Sn were deposited on Pt/Si substrates by sputtering technique and subjected to electrochemical lithiation studies. Electrochemical lithiation of Sn resulted in the formation of Sn-Li alloys of different compositions. Charging of Sn-coated Pt/Si electrodes was terminated at different potentials and the electrodes were examined for physicochemical properties. The scanning electron microscopy and atomic force microscopy images suggested that the Sn films expanded on lithiation. Roughness of the film increased with an increase in the quantity of Li present in Sn-Li alloy. Electrochemical impedance data suggested that the kinetics of charging became sluggish with an increase in the quantity of Li in Sn-Li alloy.