41 research outputs found
Astronomical spectrograph calibration with broad-spectrum frequency combs
Broadband femtosecond-laser frequency combs are filtered to
spectrographically resolvable frequency-mode spacing, and the limitations of
using cavities for spectral filtering are considered. Data and theory are used
to show implications to spectrographic calibration of high-resolution,
astronomical spectrometers
Saturation in cascaded optical amplifier free-space optical communication systems
The performance of a free-space optical (FSO) communication system in a turbulent atmosphere employing an optical amplifier (OA) cascade to extend reach is investigated. Analysis of both single and cascaded OA FSO communication links is given and the implications of using both adaptive (to channel state) and non-adaptive decision threshold schemes are analysed. The benefits of amplifier saturation, for example in the form of effective scintillation reduction when a non-adaptive decision threshold scheme is utilised at the receiver for different atmospheric turbulence regimes, are presented. Monte Carlo simulation techniques are used to model the probability distributions of the optical signal power, noise and the average bit error rate due to scintillation for the cascade. The performance of an adaptive decision threshold is superior to a non-adaptive decision threshold for both saturated and fixed gain preamplified receivers and the ability of a saturated gain OA to suppress scintillation is only meaningful for system performance when a non-adaptive decision threshold is used at the receiver. An OA cascade can be successfully used to extend reach in FSO communication systems and specific system implementations are presented. The optimal cascade scheme with a non-adaptive receiver would use frequent low gain saturated amplification
Dermatomyositis as the first manifestation of gallbladder adenocarcinoma: case report and literature overview
Lex Maritima in a changing world: development and prospect of rules governing carriage of goods by sea
This chapter examines the attempts to unifying law governing carriage of goods by sea and the background to these attempts over the past hundred years or so. It finds that a repetition of the current mode of negotiating static conventions will not unify these rules. Moreover, from historic and legal perspectives, the attempts to unify the international carriage of goods by sea regimes in the past century have remained transitional. The active players have shifted from private entrepreneurs to government delegates. This research probes into the new trade practice for the shipping industry in the twenty-first century and argues that new ‘landscape’ calls for innovative modifications of the conventional approach to unifying carriage of goods by sea rules. This research also forecasts the prospects of the Rotterdam Rules and discusses several countries’ current attitudes, including the UK, the Netherlands, Scandinavian countries and, particularly, the USA
Some New Pi-Donors - Bis(Propylene-Dithio) Tetrathiafulvalene, 4,5-Bis (Alkylthio)-1,2-Dithiolium Tetrafluorobotates and Similar Compounds
Optical buffering up to 160 Gb/s employing a quantum dot semiconductor optical amplifier-based architecture
Synthesis of Pyrazinodithiadiselenafulvalenes - New Unsymmetrical Pi-Donors
Journal URL: http://www.csj.jp/journals/chem-lett/index.htm
Bis(Alkylthio)Tetrathiafulvalenes and a Few of Their Salts
Journal URL: http://www.informaworld.com/smpp/title~content=t713644168~db=al