Wavelength converter sharing in asynchronous optical packet/burst switching: An exact blocking analysis for markovian arrivals

Cataloged from PDF version of article.In this paper, we study the blocking probabilities in a wavelength division multiplexing-based asynchronous bufferless optical packet/burst switch equipped with a bank of tuneable wavelength converters dedicated to each output fiber line. Wavelength converter sharing, also referred to as partial wavelength conversion, corresponds to the case of a number of converters shared amongst a larger number of wavelength channels. In this study, we present a probabilistic framework for exactly calculating the packet blocking probabilities for optical packet/burst switching systems utilizing wavelength converter sharing. In our model, packet arrivals at the optical switch are first assumed to be Poisson and later generalized to the more general Markovian arrival process to cope with very general traffic patterns whereas packet lengths are assumed to be exponentially distributed. As opposed to the existing literature based on approximations and/or simulations, we formulate the problem as one of finding the steady-state solution of a continuous-time Markov chain with a block tridiagonal infinitesimal generator. To find such solutions, we propose a numerically efficient and stable algorithm based on block tridiagonal LU factorizations. We show that exact blocking probabilities can be efficiently calculated even for very large systems and rare blocking probabilities, e.g., systems with 256 wavelengths per fiber and blocking probabilities in the order of 10−40. Relying on the stability and speed of the proposed algorithm, we also provide a means of provisioning wavelength channels and converters in optical packet/burst switching systems

Improvement of the Wastewater Biodegradability by Means of Photocatalytic and Wet Oxidation Processes in the Presence of Hydrogen Peroxide

In this study, the effectiveness of photocatalytic oxidation (PO) and wet oxidation (WO) processes as a pre-treatment step on improvement of biodegradability and colour removal of mixture of raw domestic and pre-treated industrial wastewaters, have been evaluated. More oxygen was obtained by H2O2 (as an oxidant in WO and PO processes) than stoichiometric demand. PO of the wastewater was carried out by illumination of the wastewater with UV lamp (at room temperature, atmospheric pressure, 16.5 h reaction time) and WO of the wastewater was carried out by means of thermal oxidation at autoclave conditions (at 118–120 oC, 1.9–2 bar, 3 h reaction time). 1 g L–1 TiO2 in PO process and 0.2 mg L–1 Cu++ in WO process were used as catalyst. The results obtained from experiments were not compared with each other due to the difference between the quality and quantity of the used catalyst and the consumed energy. Colour removal efficiency was 33 % for WO process and 77.6 % for PO process. By applying WO process, 72.7 % increase in the reaction rate coefficient describing the degradability of organic compounds in wastewater was obtained, but this value was 34.5 % in PO process

Method development and validation for the determination of cabergoline in tablets by capillary zone electrophoresis

A capillary zone electrophoresis (CZE) method has been developed for the analysis of cabergoline in its pharmaceutical preparations. Optimized analysis conditions for cabergoline analysis were performed using 110 mM pH 5.0 phosphate buffer containing 30 % acetonitrile as an electrolyte solution. Separation was performed through a fused silica capillary (50 μm i.d., total length 64.5 cm, 50.0 cm effective length) at 30 ºC with an applied voltage of 30 kV and hydrodynamic injection for 4 s. Cabergoline and internal standard verapamil were detected at a wavelength of 220 nm. The calibration was liner from 5.0 to 90.0 μg mL–1 and the limit of detection and quantification were 1.25 and 3.77 μg mL–1 Optimized CE . method was validated on the basis of related ICH guideline and found as an accurate, sensitive, precise and reproducible method for cabergoline determination. Developed method is also successfully applied for the analysis of pharmaceutical preparations containing cabergoline.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Modelling the dynamics of intramammary E. coli infections in dairy cows: understanding mechanisms that distinguish transient from persistent infections

The majority of intramammary infections with Escherichia coli in dairy cows result in transient infections with duration of about 10 days or less, although more persistent infections (2 months or longer) have been identified. We apply a mathematical model to explore the role of an intracellular mammary epithelial cell reservoir in the dynamics of infection. We included biological knowledge of the bovine immune response and known characteristics of the bacterial population in both transient and persistent infections. The results indicate that varying the survival duration of the intracellular reservoir reproduces the data for both transient and persistent infections. Survival in an intracellular reservoir is the most likely mechanism that ensures persistence of E. coli infections in mammary glands. Knowledge of the pathogenesis of persistent infections is essential to develop preventive and treatment programmes for these important infections in dairy cows

Karyotype analyses of the species of the genus Jurinea Cass. (Compositae) in Turkey

In this study, karyotype analyses of 13 species belonging to the genus Jurinea Cass. (Compositae) and grown naturally in Turkey were conducted. These taxa include Jurinea alpigena C. Koch, Jurinea ancyrensis Bornm., Jurinea aucherana DC., Jurinea cadmea Boiss., Jurinea cataonica Boiss. and Hausskn., Jurinea consanguinea DC., Jurinea cypria Boiss., Jurinea macrocalathia C. Koch., Jurinea macrocephala DC., Jurinea mollis (L.) Reichb., Jurinea pontica Hausskn. and Freyn ex Hausskn., Jurinea pulchella DC., Jurinea ramulosa Boiss. and Hausskn. Karyotype analysis of all the species are introduced to the scientific community for the first time and they were obtained through an Image analysis system. The study has made  contribution to the cytotaxonomic revision of the genus Jurinea in Turkey.Key words: Asteraceae, Image analysis, Jurinea, karyotype, Turkey

Have Usability and Security Trade-offs in Mobile Financial Services (MFS) become Untrustworthy?

The trade-off between Usability and Security has been well researched with various models proposed on how best to improve Usability without jeopardizing Security and vice visa. Usable Security has become a key factor in Mobile Financial Services (MFS), the new frontier for mobile phones utilisation. However, have the compromises gone too far? The trustworthiness of MFS system has already slowed down new adoption and impacted ongoing security trust issues and user confidence in spite of potential MFS benefits for its users. To understand this growing lack of trust with MFS, we need to comprehend the nature of Usable Security in assuring the behaviours of MFS users and determine the right trade-off to improve trust whilst facilitating future uptake. We conducted an empirical survey of 698 user’s experience of MFS and here present our findings of this investigation for further synthesis towards proposing practical control elements to assure Usable Security in MFS

Sea level changes along the Turkish coasts of the Black Sea, the Aegean Sea and the Eastern Mediterranean

Short, tidal, subtidal, seasonal, secular sea-level variations, sea-level differences and interactions between the basins have been studied, based on the data collected at some permanent and temporary tide gauges located along the Turkish coasts, mostly along the Straits connecting the Marmara Sea to outer seas. Even though the deficiency of sufficient information prevented us to reach the desired results, many pre-existed studies have been improved. Short-period oscillations were clearly identified along the Turkish Strait System and related to their natu-ral periods. The tidal amplitudes are low along the Turkish coasts, except northern Aegean and eastern Mediterranean. The stability of harmonic constants of Samsun and Antalya were examined and most of the long period constituents were found to be unstable. Even the Marmara Sea is not affected from the tidal oscillations of Black and Aegean Seas, some interactions in low frequency band have been detected. Subtidal sea level fluctuations (3-14 day) have relations with the large-scale cyclic atmospheric patterns passing over the Turkish Straits System. Short-term effects of wind on sea level are evident.Seasonal sea-level fluctuations along the Turkish Straits System are in accord with Black Sea's hydrological cycle. The differential range of the monthly mean sea levels between the Black Sea and the Marmara Sea is highly variable; high during spring and early summer and low during fall and winter.On the average, there is a pronounced sea-level difference (55 cm) along the Turkish Straits System. However, the slope is nonlinear, being much steeper in the Strait of Istanbul. This barotrophic pressure difference is one of the most important factors causing the two-layer flow through the system. The topography and hydrodynamics of the straits, the dominant wind systems and their seasonal variations make this flow more complicated. For secular sea level changes, a rise of 3.2 mm/a was computed for Karsiyaka (1935-71) and a steady trend (-0.4 mm /a) has been observed for annual sea levels at Antalya (1935-77). The decreasing trend (-6.9 mm/a) at Samsun is contrary to the secular rising trend of the Black Sea probably because of its rather short monitoring period (1963-77)

Effect of BaCeO₃ and BaSnO₃ Additives on Microstructural Development and Critical Current Density of Melt Textured YBa₂Cu₃O₇₋ₓ

Improvement of superconducting properties, such as critical current density Jc and trapped magnetic field, of melt textured YBa2Cu3O7-x (Y123) require introducing of effective pinning sites, e.g., nonsuperconducting inclusions, twin boundaries and other defects. It has been shown that addition of small quantities of BaCeO3 (\u3c0.5 wt%) into Y123 results in an increase of the Jc. However, higher cerium concentrations affect the solidification process and inhibit the growth of melt textured Y123 single crystals. In this study, the effect of BaCeO3 additions on the growth and microstructural development of melt textured Y123 single crystals were investigated. The relationship between the solidification kinetics, microstructural development and superconducting properties of Y123 melt textured single crystals with cerium additives is discussed