NEC

About: NEC is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 33269 authors who have published 57670 publications receiving 835952 citations. The organization is also known as: NEC Corporation & NEC Electronics Corporation.

Input power limits of single-mode optical fibers due to stimulated Brillouin scattering in optical communication systems

Abstract: Stimulated Brillouin scattering (SBS) limits the optical power that can be transmitted through a single-mode fiber in long-distance optical communication systems, the authors have investigated SBS gain and threshold characteristics with amplitude-shift-keying (ASK), frequency-shift-keying (FSK), and phase-shift-keying (PSK) modulated lights to estimate the input power limitation set by SBS. It was shown that maximum fiber-input powers or the SBS thresholds for fixed-pattern (1010 . . .) ASK, FSK, and PSK modulated lights are 2, 4, and 2.5 times higher, respectively, than the threshold for unmodulated light. Theoretical predictions were experimentally verified by SBS gain measurements with FSK and PSK modulated lights. The first direct observation of SBS with FSK modulated light pumping is also described. >

Kenaf‐fiber‐reinforced poly(lactic acid) used for electronic products

Abstract: We have developed high-performance biomass-based plastics that consist of poly(lactic acid) (PLA) and kenaf fiber, which fixates CO2 efficiently. Adding this fiber to PLA greatly increases its heat resistance (distortion temperature under load) and modulus and also enhances its crystallization, so the ease of molding this material is improved. Eliminating the short particles from the kenaf fiber improves its effect on the impact strength. Kenaf fiber without the particles exhibits effects on these characteristics of PLA practically comparable to the effects of glass fiber. Furthermore, adding a flexibilizer (a copolymer of lactic acid and aliphatic polyester) to the composites improves their strength. These composites (PLA/kenaf fiber and PLA/kenaf fiber/flexibilizer) show good practical characteristics for housing materials of electronic products in comparison with petroleum-based plastics used in housing such as glass-fiber-reinforced acrylonitrile-butadien-styrene (ABS) resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 618–624, 2006

Call control with transmission priority in a packet communication network of an ATM type

Abstract: In a high-speed packet multiplex communication network including a transmission line with a predetermined bandwidth and accommodating a plurality of information sources, the sources having various packet delivery rates over a range of between a peak rate and a lower rate than an average rate and demanding various transport performances, the sources are preliminarily classified into a plurality of types according to transport performances required and different transmission priorities are assigned to the different types, respectively. Bandwidths of sources of first priority and second priority are determined ones corresponding to the peak rate and the average rate, respectively. A virtual bandwidth may be calculated for the second priority source as a value between the peak and average rates. In response to connection requests from the sources, each of the connection requests is admitted when a bandwidth defined by the priority of each source is accepted in a residual bandwidth of the predetermined bandwidth, and the packets from the source of the first priority are preferentially transmitted to the transmission line, packets of the second priority source are transmitted when packets of the first priority source are absent. Thus, high bandwidth efficiency is insured while the high transport performance of the first priority source is maintained.

Graphitic ribbons without hydrogen-termination: Electronic structures and stabilities

Abstract: The graphitic ribbons with H termination have been the subject of recent studies, but we investigated the ribbons without H termination using tight-binding and first-principles calculations. The ribbons with armchair edge were found to have phonon frequencies near 2000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ which has been solely ascribed to the one-dimensional carbon allotrope, carbyne. Comparative studies of the formation energies suggest that ribbons will grow more easily in the direction perpendicular to the zigzag edge, consistent with a recent experiment.

The impact of bias temperature instability for direct-tunneling ultra-thin gate oxide on MOSFET scaling

Abstract: This paper presents a new reliability scaling scenario for CMOS devices with direct-tunneling ultra-thin gate oxide. Device degradation due to bias-temperature instability (BTI) was studied. First, the stress voltage dependence of BTI results indicate that the direct-tunneling electron and/or hole transport does not play a major role in the degradation mechanism. Secondly, it was found that the threshold voltage change caused by BTI for the PMOSFET limits the device lifetime, which is shorter than that defined by hot-carrier induced degradation for the NMOSFET. It originates from the difference of supply voltage dependence between BTI and hot-carrier degradation.