PHASE ERRORS AND DOPPLER EFFECT IN DIGITAL COMMUNICATIONS

The rollout of IEEE 802.16e for high speed mobile communications poses challenges to the design of equalizers for a time-varying multipath fading channel. This thesis investigates the effects of Doppler shift induced phase error in a wireless environment. It presents the performance of QPSK and MQAM waveforms with Doppler in a Rayleigh channel condition. It investigates the performance of ideal coherent modulation and pilot symbol-aided modulation in a Rayleigh channel with Doppler phase errors. The degradation in performance of pilot symbol-aided demodulation as compared to ideal coherent demodulation is presented. The study concludes with results of simulations of QPSK and MQAM waveforms in a Rayleigh Channel with Doppler phase errors.Civilian, Singapore Defence Science & Technology AgencyApproved for public release; distribution is unlimited

Edge-coloring vertex-weighting of graphs

Let G = (V (G),E(G)) be a simple, finite and undirected graph of order n. A k-vertex weighting of a graph G is a mapping w: V (G) → {1,…, k}. A k-vertex weighting induces an edge labeling fw: E(G) → N such that fw(uv) = w(u) + w(v). Such a labeling is called an edge-coloring k-vertex weighting if fw(e)≠ fw(e′) for any two adjacent edges e and e′. Denote by μ′(G) the minimum k for G to admit an edge-coloring k-vertex weighting. In this paper, we determine μ′(G) for some classes of graphs

Oil palm biomass wastes as renewable energy sources in Malaysia: potentials and challenges

This paper reviews the potentials and challenges of using Oil Palm Biomass Wastes (OPBW) as Renewable Energy (RE) source in Malaysia. The OPBW mainly includes Palm Oil Mill Effluent (POME) and Empty Fruit Bunches (EFB). From the present review, the major potentials of OPBW consist of their large availability, being a major sources of lignocellulosic materials for industrial, being economically viable, being a solution to the disposal problem and cost-benefit. The challenges of using OPBW as RE source are being a high dependency on the availability of the OPWB, unfair subsidies given to RE based fuel, the use of POME that produces methane, substantial amount of under-utilization of lignocellulosic wastes from OPBW, the need for further studies on the correct selection of generation plant size, and not economically competitive. Overall, the challenge is to make the OPBWs as a reliable, profitable and sustainable RE industry. Based on the present review mainly from Malaysia, there are definite potentials/advantages of using OPBW as RE source in Malaysia. Ways and suggestions on these practical issues on how to reduce problems facing the use of OPBW as RE source in Malaysia should be investigated and addressed before the large scale utilization of OPBW as RE source can be anticipated in Malaysia

Serotonin transporter polymorphisms and clinical response to sertraline across ethnicities

The aim of this pilot study was to examine the relationship between clinical response, adverse effects, sertraline (SERT) plasma concentrations and the genetic polymorphism of the serotonin transporter gene-linked polymorphic region (5HTTLPR) in 2 ethnic patient groups. The study involved 45 patients in a clinical trial who received a fixed dose regimen of 50 mg SERT for one week, then a variable-dose regimen for a further 6 weeks for major depressive disorder. At weeks 1 and 6, the following assessments were completed: Hamilton Depression Rating Scale (HDRS), Clinical Global Impression (CGI), drug adverse reaction scale and measurement of plasma SERT levels. Genomic analysis for the long and short allele variants of the 5HTTLPR polymorphism was also carried out. Caucasian subjects had a higher rate of l/l genotype while Chinese subjects had higher frequencies of l/s and s/s genotypes. Comparison of the subjects with the 5HTTLPR s/s genotype and those with the l/l and l/s genotypes found no significant differences in the HDRS scores, CGI scores, response rates, adverse effects and SERT plasma concentrations at week 6