1 Tbit/s (111 Gbit/s/ch X 10 ch) no-guard-interval CO-OFDM transmission over 2100 km DSF

Spectrally efficient (2bit/s/Hz) 1 Tbit/s DWDM transmission of 111 Gbit/s no-guard-interval PDM CO-OFDM signals with 50 GHz spacing over DSF is demonstrated. The record transmission distance of 2100 km was achieved for a 100 Gbit/s-data-rate CO-OFDM system.     

Theatre in the Sky: a ubiquitous broadband multimedia‐on‐demand service over a novel constellation composed of quasi‐geostationary satellites

To meet an ever‐growing demand for wideband multimedia services and electronic connectivity across the world, development of ubiquitous broadband multimedia systems is gaining a tremendous interest at both commercial and academic levels. Satellite networks will play an indispensable role in the deployment of such systems. A significant number of satellite communication constellations have been thus proposed using Geostationary (GEO), Medium Earth Orbit (MEO), or Low Earth Orbit (LEO) satellites. These constellations, however, either require a potential number of satellites or are unable to provide data transmission with high elevation angles. This paper proposes a new satellite constellation composed of Quasi‐GeoStationary Orbit (Quasi‐GSO) satellites. The main advantage of the constellation is in its ability to provide global coverage with a significantly small number of satellites while, at the same time, maintaining high elevation angles. Based on a combination of this Quasi‐GSO satellites constellation and terrestrial networks, the paper proposes also an architecture for building a global, large‐scale, and efficient Video‐on‐Demand (VoD) system. The entire architecture is referred to as a ‘Theatre in the Sky’. Copyright © 2006 John Wiley & Sons, Ltd.     

PMD compensation in optical coherent single carrier transmission using frequency-domain equalisation

The transmission performance of optical single-carrier (SC) transmission using frequency-domain equalisation (FDE) to counter polarisation mode dispersion (PMD) is evaluated. 25 Gbit/s coherent optical SC transmission using FDE (CO-SC-FDE) is demonstrated in the presence of a significant amount of differential group delay (DGD). The results show that CO-SC-FDE compensates for the influence of the 125 ps DGD; the OSNR penalty is 0.81 dB.     

Gain and the threshold of three-dimensional quantum-box lasers

Gain and threshold current density are analyzed for quantum-box lasers where electrons are confined in quantum well three-dimensionally, based on the density-matrix theory of semiconductor lasers with relaxation broadening. The electronic dipole moment and its polarization dependence are first analyzed, and it is shown that the gain becomes maximum when the electric field of light is parallel to the longest side of the quantum box. Calculated gain is about 10 times that of bulk crystal for 100 Å × 100 Å × 100 Å GaAs/Ga0.8Al0.2As quantum box, and 15 times for Ga0.47In0.53As/InP quantum box with the same size, respectively. The threshold current density are 45 A/cm²and 62 A/cm²for GRINSCH GaAs/(Ga0.8Al0.2As-Ga0.4Al0.6As) and Ga0.47In0.53As/(Ga0.28In0.72As0.6P0.4-InP), respectively, where for the GaInAs/ GaInAsP/InP system the intervalence band absorption and nonradiative recombinations have been assumed to be the same as those obtained for bulk crystals experimentally. These results show the possibility of remarkable reduction in the laser threshold by the quantum-box structures.     

Influence of side chain length on fluorescence intensity of ROMP-based polymeric nanoparticles and their tumor specificity in in-vivo tumor imaging

In this study, amphiphilic brush-like copolymers conjugated with short alkyl or long polymeric chains of various lengths are synthesized using ring-opening metathesis polymerization (ROMP) of substituted norbornadiene monomers followed by chemical transformations. These amphiphilic copolymers form spherical self-assemblies in aqueous media with diameters of 132-244 nm. The low critical aggregation concentration of these assemblies (2.5 × 10(-3) -1.4 × 10(-5) g/L) indicates that they are quite stable in dilute conditions. An appropriate length of polymer side chain that conjugates the polymer backbone with a hydrophobic ICG (indocyanine green) moiety enhanced the fluorescence intensities of these self-assemblies in aqueous solution as well as in tumor-bearing mice. A longer side chain conjugated with tumor targeting agents could significantly affect the tumor specificity of self-assemblies to a greater extent. The self-assemblies bearing hydrophilic tumor targeting agents, such as a glucosamine molecule and a cyclic RGD (arginine-glycine-asparatic acid) peptide, accumulated in tumor tissues with high selectivity, while those having a hydrophobic targeting agent, such as folate moieties, accumulated in tumor sites with low selectivity. The results demonstrated here unambiguously indicate that the fluorescence intensity and tumor specificity of self-assemblies are strongly affected by the length of side chains that conjugate with dyes and targeting agents.     

Biomimetic assembly of proteins into microcapsules on oil-in-water droplets with structural reinforcement via biomolecular-recognition-based cross-linking of surface peptides

By mimicking the stabilization of bacterial membranes with S-layer proteins, a novel process to fabricate highly stable protein microcapsules is introduced. In this strategy, engineered collagen peptides with site-specific biotinylation are assembled into microcapsules on the oil-in-water droplets, and the resulting microcapsules are reinforced by biomolecular-recognition-based cross-linking with the protein. Furthermore the microcapsules are shown to be versatile scaffolds for developing functionalized hierarchical colloidosomes for important biotechnological applications.     

Modeling of Nonlinear Magnetizing Characteristics of Pole Transformer for Analyzing Islanding Prevention of Photovoltaic System

With increasing penetration of distributed generators such as photovoltaic (PV) systems in distribution systems, it is very important to quickly detect islanding caused by power system faults in order to assure electrical safety. We have developed a nonlinear magnetizing characteristics model of pole transformers for use in analyzing islanding prevention in PV systems. Basic experiments on the islanding detection were performed for verification of the proposed model. Analytical results obtained by the proposed model agreed well with experimental results.     

Mechanism of Catalytic Effects on AMMO/HMX Composite Propellants Combustion Rates

Thermal decomposition and the burning properties of AMMO/HMX propellants have been investigated. The heat generated by the AMMO decomposition initiated and accelerated the thermal decomposition of HMX, and the reaction between decomposed AMMO and HMX depended upon the heating rate. The rate determining step of the reaction path was different in higher and lower heating rate conditions. 2,2-bis(ethylferrocenyl)propane (CFe) and copper chromite (CuC) significantly altered the mechanisms of the thermal decomposition and the burning properties. CFe showed an increase in burning rate with a slight increase in burning rate exponent. However, CuC yielded high values for the burning rate exponent. The combined additive yielded the highest burning rate with the lowest burning rate exponent. The influence of CuC on the burning rate exponent disappeared by the combination with CFe. Though CFe and the combination additive improved the ignitability of the propellants, the propellant with CuC was difficult to ignite because of the relatively small quantity of heat feedback and/or heat released by the decomposition.     

Neutronic and thermodynamic feasibility of UF6-NpF6 fueled transmutation reactor

Transmutation of neptunium, which is contained in radioactive wastes discharged from nuclear reactors, was investigated as a substitutional method for geologic disposal. We proposed a transmutation reactor fueled with a mixture of gaseous ²³³UF₆ and ²³⁷NpF₆. Neutronic and thermodynamic analysis of the reactor revealed the feasibility of the concept. The reactor has two principal advantages: (1) use of the fuel gas enables on-line reprocessing, (2) ²³⁷Np can be transmuted by a high neutron flux. Our calculation indicated that the transmutation rate of ²³⁷Np was 335 g/year/MW_th, which is much larger than the annual yield of ²³²Np in PWR (6.19 g/year/MW_th).