5,102 research outputs found
Directly modulated CWDM/DWDM system using negative dispersion fiber for metro network application
No full textWe demonstrate the error-free transmission of directly modulated 2.5, 10, and 40-Gb/s coarse wavelength-division-multiplexing/dense wavelength-division-multiplexing signals over negative dispersion fiber (dispersion: -2.5 ps/km/nm @ 1550 nm) without dispersion compensation. The results indicate that the metro core/access network could be implemented cost-effectively by using the proposed negative dispersion fiber and directly modulated lasers. (C) 2004 Elsevier B.V. All rights reserved
Directly modulated 10 Gb/s signal transmission over 320 km of negative dispersion fiber for regional metro network
No full text40 Gb/s x 8 channels WDM transmission at 100-GHz spacing over 320 km of short-period dispersion-manged fiber (Perfect Cable)
No full text
A linear affect-expression space model and control points for mascot-type facial robots
No full textA robot's face is its symbolic feature, and its facial expressions are the best method for interacting with people with emotional information. Moreover, a robot's facial expressions play an important role in human-robot emotional interactions. This paper proposes a general rule for the design and realization of expressions when some mascot-type facial robots are developed. Mascot-type facial robots are developed to enable friendly human feelings. The number and type of control points for six basic expressions or emotions were determined through a questionnaire. A linear affect-expression space model is provided to realize continuous and various expressions effectively, and the effects of the proposed method are shown through experiments using a simulator and an actual robot system
A study on the adhesion enhancement of polyetherimide to Si wafer using an Al-chelate treatment during multichip module fabrication
No full textAl-chelate coupling agent was successfully applied to improve the adhesion strength of a thermoplastic polyetherimide resin, Ultem 1000 (R) to a silicon wafer during the fabrication of multichip module (MCM) substrates, The origin of the enhanced adhesion strength achieved by applying Al chelate was also investigated using a surface characterization experiment and a theoretical approach. The peel strength of as-laminated Ultem film on an untreated Si wafer was the same as that on a coupler-treated one right after lamination. However, the Ultem layer laminated on an untreated Si wafer lost its adhesion strength to zero within 24 h of 85 degrees /85% relative humidity (RH) aging. In contrast, the Ultem film laminated on the coupler-treated Si wafer maintained its adhesion strength even after 30 days of 85 degreesC/85% RH treatment. Atomic force microscopy (AFM), surface energy calculation using contact angle measurement, and high-resolution X-ray photoelectron spectroscopy (XPS) analysis were conducted to characterize the surface conditions of a bare Si wafer and a coupler-treated Si wafer. It was revealed by the AFM experiment that the surface roughening caused by Al-chelate treatment was negligible, meaning that the enhanced adhesion stability during 85 degreesC/85% RH aging is mainly attributed to the surface characteristic change of Si substrate. Based on the results of XPS analysis and contact angle measurement, a model of surface bonding structure of an Al-chelate treated Si wafer was suggested and compared with that of a bare Si wafer. Finally, peel strength variation of Si wafers with and without the coupling agent as a function of 85 degreesC/85% RH aging times can be explained by the zero point of charge consideration. Stable lamination based MCMs and micro-via build-up processes can also be obtained using these results. (C) 2001 Elsevier Science B.V. All rights reserved
Four-sector cross-shaped urban microcellular systems with intelligent switched-beam antennas
No full textA four-sector cross-shaped urban microcellular system with intelligent switched-beam antennas is proposed. Each sector covers a street block with a base station located at an intersection, and an intelligent beam-switching scheme is used to locate mobile users in the most suitable beam coverage. Due to directional narrow-beam patterns and waveguide effects of tall buildings, radio signals along vertical and horizontal streets do not interfere with each other. Therefore, a channel can be reused simultaneously in multiple neighboring cells as long as cochannels do not encounter each other along the line of sight. The proposed scheme has a channel reuse efficiency of 0.95 for a traffic load of 0.02 [new-call arrivals/s/cell]. The system also increases system capacity more than three times with a blocking probability of 1% and considerably reduces handoff traffic when compared with a conventional cross-shaped microcellular system with an omnidirectional beam pattern
Finite-wall effect on buoyant convection in an enclosure with pulsating exterior surface temperature
No full textA numerical study is made of the finite-wall effect in the benchmark-configuration buoyant convection in a square cavity at large Rayleigh number. A general formulation, with one vertical sidewall of finite thickness and thermal conductivity, is presented. Firstly, the finite-wall effect for the case of non-pulsating boundary temperature condition is delineated. The energy balance consideration, together with the preceding empirical correlations, leads to a simple formula to predict the temperature at the interior surface of the finite-thickness wall. The analytical predictions are shown to be consistent with the results of full-dress Navier Stokes numerical solutions. Secondly, the finite-wall effect for the case of pulsating boundary temperature condition is explored. The numerical results illustrate that the amplitude of oscillating Nusselt number. A(Nu), at the central plane peaks at a particular pulsation frequency. This has been interpreted to be a manifestation of resonance. The finite-wall effect on the shift of resonance frequency is discussed. The temperature oscillation at the interior surface of the solid wall is examined. and the convection-modified modified model is introduced to describe the alteration in the temperature contrast across the fluid portion. The estimation of the resonance frequency. based on the internal gravity oscillations, is shown to be in accord with the Navier-Stokes numerical solutions. (C) 2001 Published by Elsevier Science Ltd
- …
