Wavelength tuning of fiber Bragg gratings over 90 nm using a simple tuning package

We demonstrate a silica-based tunable fiber Bragg grating filter with a wavelength tuning range over 90 nm. A bend-tuning technique in a simple tuning package is employed to obtain a wide wavelength tuning range from 1634 to 1544 nm, covering the entire L-band and a half of the C-band. The polarization-mode dispersion and polarization-dependent loss of the device show little variations over the whole operating region.     

Adaptive wavelength routing in all-optical networks

We consider routing and wavelength assignment in wavelength-routed all-optical networks (WAN) with circuit switching. The conventional approaches to address this issue consider the two aspects of the problem disjointly by first finding a route from a predetermined set of candidate paths and then searching for an appropriate wavelength assignment. We adopt a more general approach in which we consider all paths between a source-destination (s-d) pair and incorporate network state information into the routing decision. This approach performs routing and wavelength assignment jointly and adaptively, and outperforms fixed routing techniques. We present adaptive routing and wavelength assignment algorithms and evaluate their blocking performance. We obtain an analytical technique to compute approximate blocking probabilities for networks employing fixed and alternate routing. The analysis can also accommodate networks with multiple fibers per link. The blocking performance of the proposed adaptive routing algorithms are compared along with their computational complexity     

Joule Heating Characteristics of Emulsion‐Templated Graphene Aerogels

The Joule heating properties of an ultralight nanocarbon aerogel are investigated with a view to potential applications as energy‐efficient, local gas heater, and other systems. Thermally reduced graphene oxide (rGO) aerogels (10 mg cm^?3) with defined shape are produced via emulsion‐templating. Relevant material properties, including thermal conductivity, electrical conductivity and porosity, are assessed. Repeatable Joule heating up to 200 °C at comparatively low voltages (≈1 V) and electrical power inputs (≈2.5 W cm^?3) is demonstrated. The steady‐state core and surface temperatures are measured, analyzed and compared to analogous two‐dimensional nanocarbon film heaters. The assessment of temperature uniformity suggests that heat losses are dominated by conductive and convective heat dissipation at the temperature range studied. The radial temperature gradient of an uninsulated, Joule‐heated sample is analyzed to estimate the aerogel's thermal conductivity (around 0.4 W m^?1 K^?1). Fast initial Joule heating kinetics and cooling rates (up to 10 K s^?1) are exploited for rapid and repeatable temperature cycling, important for potential applications as local gas heaters, in catalysis, and for regenerable of solid adsorbents. These principles may be relevant to wide range of nanocarbon networks and applications.     

Electrical studies on a single,binary, and ternary nanocomposites of Mn3O4@TiO2@rGO

Journal of Materials Science: Materials in Electronics - The present work is concerned with studying the electrical and dielectric properties of a single, binary, and ternary nanocomposite of Mn3O4...     

Dye adsorption and desorption properties of Mentha pulegium in single and binary systems

This article deals with the dye adsorption and desorption properties of Mentha pulegium (MP) from single and binary (mixture of dyes) systems. Direct Red 80 (DR80) and Acid Black 26 (AB26) were used as model dyes. The Fourier transform infrared (FTIR) was used to investigate the biosorbent characteristics. The effects of biosorbent dosage, contact time, dye concentration, salt, and pH on dye removal were studied. The biosorption isotherms, kinetics, and thermodynamic were studied. In addition, dye desorption was carried out to study adsorbent recovery. The results showed that the isotherm data of single and binary systems of dyes followed the Langmuir isotherm. The adsorption kinetic of the dyes was found to conform to a pseudosecond order kinetic model. Desorption tests showed maximum dye releasing of 97% for DR80 and 95% for AB26 in single system and 92% for DR80 and 94% for AB26 in binary system of dyes at pH 12. The thermodynamic data showed that the biosorption process is spontaneous, endothermic, and a physisorption reaction. It can be concluded that MP is an ecofriendly biosorbent to remove dyes from single and binary systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrochemical behaviour of some 3-methylthio-1,2-dithiolium cations in dimethylformamide solution

Substituted 3-methylthio-1,2-dithiolium cations were prepared by alkylation of the corresponding 1,2-dithiole-3-thiones. These compounds were easily reduced in DMF at a mercury electrode, following two one-electron waves. Electrolysis, carried out at a mercury pool electrode and followed by an alkylation or an acylation, provided the corresponding alkyl (or acyl) dithioesters and by-products. At a platinum or glassy carbon electrode the reduction was an irreversible process, which was dependent upon the cathode nature. Whatever the electrode, the reduction was a combination of two reactions, a two-electron reduction and a one-electron one involving a dimerization. The electrochemical behaviour of 3-methylthio-1,2-dithiolium cations exhibited many analogies with the cathodic behaviour of the corresponding 1,2-dithiole-3-thiones. Moreover, identical intermediates were implicated in the reduction of 3-methylthio-1,2-dithiolium cations and in the reductive alkylation of 1,2-dithiole-3-thiones.     

An optimal open-loop multimode fiber gyroscope for rate-grade performance applications

We report the realization of a new version of a fiber optic gyroscope (FOG), using low-cost multimode fiber components. This is achieved by an optimal choice of the components such as fiber, coupler, light source and photodetector. The aim behind this work is to demonstrate the versatility of the low-cost multimode FOG for rate-grade performance applications. Both analog signal processing and open-loop operation are used in the proposed FOG experiment. The obtained sensitivity is ∼7°/h and the angle random walk is about 0.087°/. The influence of the coupler technology on the performances is investigated.     

Characterisation and quantification of phenolic compounds of extra-virgin olive oils according to their geographical origin by a rapid and resolutive LC–ESI-TOF MS method

The phenolic compounds present in seven samples of olive fruits were analysed by a rapid and resolutive LC–ESI-TOF MS method. All samples were collected during the normal picking period for olive oil production, in central and south Tunisia, and were obtained from the Oueslati variety cultivated in different olive growing areas.     

Institutional challenges for integrated river basin management in Langat River Basin,Malaysia

This paper reports on a study of the institutional challenges and factors affecting policy processes and outcomes of integrated river basin management (IRBM) in the Langat River Basin (LRB), Malaysia. A case study approach using institutional analysis and development (IAD) framework was used, and field observations and interviews with local stakeholders of LRB were carried out. The study revealed that polycentric institutional arrangements under the Federal administration are likely capable of coordinating and integrating river basin management by extending the scope of an iterative learning through participation of individual stakeholder at the lowest appropriate level. There should also be an iterative learning mechanism within the interorganizational network for IRBM in LRB. This learning approach is conceptualized as social learning and accordingly a framework is recommended for LRB. The findings of this study would be useful to those who are concerned with successful IRBM implementation in LRB and elsewhere.