7dB optical power budget improvements of 11.25Gb/s optical OFDM PON systems using optical filters

Wavelength offset super Gaussian optical filters enable 7dB increases in optical power budget of 11.25Gb/s optical OFDM PON systems using directly modulated DFBs, considerably relax filter bandwidth requirement and improve performance robustness to bandwidth variation. © 2011 Optical Society of America.

7dB optical power budget improvements of optical OFDM PON systems using narrow optical filters

The use of 0.02nm bandwidth optical bandpass filters with 0.01nm wavelength offsets from optical carrier wavelengths in the optical OFDM (OOFDM) transmitter improves optical power budgets by 7dB at a total channel BER of 1×10 -3 in directly modulated laser-based IMDD PON systems. ©2010 Optical Society of America.

Fabrication of high-Q film bulk acoustic resonator (FBAR) filters withcarbon nanotube (CNT) electrodes

FBAR devices with carbon nanotube (CNT) electrodes have been developed withthe aim of taking advantage of the low density and high acoustic impedance ofthe CNTs compared to other known materials. The influence of the CNTs on thefrequency response of the FBAR devices was studied by comparing two identicalsets of devices, one set comprised FBARs fabricated with chromium/gold bilayerelectrodes, and the second set comprised FBARs fabricated with CNT electrodes.It was found that the CNTs had a significant effect on attenuating travellingwaves at the surface of the FBARs membranes due to their high elastic stiffness.Finite element analysis of the devices fabricated was carried out using COMSOLMultiphysics, and the numerical results confirmed the experimental resultsobtained. © 2010 IEEE.

Heterogeneous reconfigurable system for adaptive particle filters in real-time applications

This paper presents a heterogeneous reconfigurable system for real-time applications applying particle filters. The system consists of an FPGA and a multi-threaded CPU. We propose a method to adapt the number of particles dynamically and utilise the run-time reconfigurability of the FPGA for reduced power and energy consumption. An application is developed which involves simultaneous mobile robot localisation and people tracking. It shows that the proposed adaptive particle filter can reduce up to 99% of computation time. Using run-time reconfiguration, we achieve 34% reduction in idle power and save 26-34% of system energy. Our proposed system is up to 7.39 times faster and 3.65 times more energy efficient than the Intel Xeon X5650 CPU with 12 threads, and 1.3 times faster and 2.13 times more energy efficient than an NVIDIA Tesla C2070 GPU. © 2013 Springer-Verlag.

16 chip, 18 Gchips/s walsh-code implementation of an ECDMA access network using two time-shifted FIR filters

We demonstrate for the first time an electronically processed Walsh Code with 16 chips at 18Gchip/s. An auto-cross correlation ratio of 18.1dB is achieved between two orthogonal codes after transmission over 10km of SMF. © 2009 OSA.

Perceptual thresholds for detecting modifications applied to the acoustical properties of a violin

This study is the first step in the psychoacoustic exploration of perceptual differences between the sounds of different violins. A method was used which enabled the same performance to be replayed on different "virtual violins," so that the relationships between acoustical characteristics of violins and perceived qualities could be explored. Recordings of real performances were made using a bridge-mounted force transducer, giving an accurate representation of the signal from the violin string. These were then played through filters corresponding to the admittance curves of different violins. Initially, limits of listener performance in detecting changes in acoustical characteristics were characterized. These consisted of shifts in frequency or increases in amplitude of single modes or frequency bands that have been proposed previously to be significant in the perception of violin sound quality. Thresholds were significantly lower for musically trained than for nontrained subjects but were not significantly affected by the violin used as a baseline. Thresholds for the musicians typically ranged from 3 to 6 dB for amplitude changes and 1.5%-20% for frequency changes. interpretation of the results using excitation patterns showed that thresholds for the best subjects were quite well predicted by a multichannel model based on optimal processing. (c) 2007 Acoustical Society of America.

Stainless steel sandwich

The Cambridge University's Gordon Laboratory, in collaboration with Fibertech and the Defence Science and Technology Laboratory in the UK, has developed a novel melt spun fiber bore called 'Fibrecore', fabricated entirely from stainless steel with thin faceplates. Fibrecore is typically manufactured by 5mm-long and 70μm thick stainless steel fibers, produced by a melt overflow process. Its entirely metallic construction allows spot welding and tungsten inert gas welding without difficulty. Fibrecore exhibits different energy absorption mechanisms such as core cushioning, core-faceplate delamination, and plastic faceplate deformation, often in a concertina-like fashion. Its low-cost, high structural efficiency and good energy absorption characteristics make it attractive for a range of commercial and military applications. Such applications being evaluated include vehicle body panels, exhaust system noise reduction, low cost filters, and lightweight physical protection. In addition to these characteristics, Fibrecore exhibits properties such as corrosion protection, vibrational damping, and thermal insulation, which also extend its applications.