A WDM-PON Employing Fabry–PÉrot Laser Diodes Without a Seed Light Injection

We propose and demonstrate a wavelength-division-multiplexed passive optical network by employing double-contact Fabry-Perot laser diodes (F-P LDs) without a seed light injection. To avoid the high mode partition noise at low frequency, we use a binary phase-shift keying as a modulation format at a low relative intensity noise window. An error-free transmission is achieved by compensating a lasing envelope shift due to temperature variation with the double-contact F-P LD.     

Bandwidth allocation algorithms for weighted maximum rate constrained link sharing policy

This paper addresses the problem of bandwidth allocation under the weighted maximum rate constrained link sharing policy and proves a key theory in the condition of allocation termination. We propose several algorithms with various worst-case and average-case time complexities, and evaluate their computation elapse times.     

Mobile Social Networks and Social Practice: A Case Study of Dodgeball

A mobile social network system (MSNS) allows groups of friends to be accessed and engaged with from one's mobile phone. Dodgeball is a MSNS that seeks to facilitate social connection and coordination among friends in urban public spaces. Based on a year-long qualitative field study, this article reports on the social and behavioral norms of Dodgeball use. A comparison between social network sites and Dodgeball highlights some of the communicative differences of mobile technology and the Internet. The findings of the study suggest that Dodgeball use can influence the way that informants experience public space and social relations therein. At times Dodgeball can facilitate the creation of third spaces, which are dynamic and itinerant forms of "third places." Additionally, exchanging messages through Dodgeball can lead to social molecularization, whereby active Dodgeball members experience and move through the city in a collective manner.     

Interaction between bubbles and fibre optic probes in a bubble column

Spherical bulb fibre optic probes, developed and applied for bubble characterization in a bubble column and a slurry bubble column at high temperature, were investigated. The principle of operation of these new optical fibre probes is based on the difference in refractive indices between the gas and the liquid phases. The interaction between the gas bubbles and the fibre optic probes in a bubble column was studied using photographic techniques. The first objective of these experiments was to study the response of the sensors upon contact with gas bubbles of various sizes. The second objective of this study was to establish, under controlled situations, the optical probe bubble detection performance and ability for local quantitative measurements of the bubble rise velocity and the gas hold-up.     

Simulation of polarization converter formed by poling-inducedpolymer waveguides

A polarization converter using electrooptic (EO) polymer waveguides is proposed and it is simulated by a full vectorial beam propagation method (VBPM) for anisotropic medium. First, an efficient structure of poling electrodes is proposed for the fabrication of TE-mode poling-induced waveguides in EO polymer. For given electrode structures of both TE-mode and TM-mode waveguides, poling-induced dielectric tensors are calculated by the finite-element method to provide refractive index distribution, data for VBPM simulation. It is shown numerically that the poled TE and TM mode waveguides work efficiently as the corresponding polarization filters. Then, new poling electrodes are suggested to fabricate a waveguide device formed by connecting the TE and TM mode waveguides adiabatically with a slowly varying structure. This waveguide device has the optic axis slowly rotating as one moves along the propagation direction, so that it will act as polarization converter. VBPM simulation shows that the polarization of the guided mode rotates following the optic axis distribution. Polarization conversion is demonstrated successfully with high conversion efficiency and low excess loss     

Chemical processing and characterization of spinel-type thermistor powder in the Mn-Ni-Fe oxide system

The coprecipitated Mn-Ni-Fe oxalate was prepared from the mixed sulfate solution by optimum pH control. The chemical composition agreed well with that of the starting solution, and the thermal decomposition of the Mn-Ni-Fe oxalate in air below 600 °C led to the direct formation of cubic spinel phase with fine particle size. The sinterability of the calcined powder, the stability of cubic spinel phase and the influence of annealing temperature on electrical properties of the sintered bodies, were investigated.