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.

Piezoelectric ceramic transformer operating in thickness extensional vibration mode for power supply

Abstract: A new kind of multilayer piezoelectric ceramic transformer for switching regulated power supplies is described. This transformer operates in the second thickness extensional vibration mode. Its resonant frequency is higher than 1 MHz. Theoretical calculations are implemented using a distributed constant electromechanical equivalent circuit method. It is calculated that this transformer can operate with higher than 90% efficiency. A fabricated transformer is examined. PbTiO/sub 3/ family ceramics are used because of the large anisotropy between electromechanical coupling factors. Results indicate that the piezoelectric transformer has good resonant characteristics, with little spurious vibration, and exhibits 16 W/cm/sup 3/ power density with high efficiency at 2 MHz. A switching regulated power supply, applying the piezoelectric transformer, is built and examined. >

Site identification of carboxyl groups on graphene edges with Pt derivatives.

Abstract: Although chemical functionalization at carboxyl groups of nanocarbons has been vigorously investigated and the identities and quantities of the carboxyl groups have been well studied, the location of carboxyl groups had not previously been clarified Here, we show that site identification of carboxyl groups is possible by using Pt−ammine complex as a stain After Pt−ammine complexes were mixed with graphenes in ethanol, many Pt−ammine complex clusters with an average size of about 06 nm were found to exist at edges of graphene sheets, indicating that the carboxyl groups mainly existed at the graphene edges These results will make it easier to add functionalities by chemical modifications for various applications of nanotubes and other nanocarbons

Semiconductor memory device having ECC type error recovery circuit

Abstract: A semiconductor memory device having an error check and correction (ECC) type error recovery circuit in which disposition of ECC cells is improved. The memory device comprises: a memory cell array including a plurality of normal cell array portions and an ECC cell array portion; an X decoder for selecting one of word lines in the memory cell array, the word lines extending from the X decoder to the memory cell array; an ECC operation circuit for performing error check and correction based on cell data read out from a selected word line, the cell data including data from normal cells and ECC cells of the selected word line. The ECC memory cell array portion is disposed at a location other than the far end of the word lines from the X decoder, that is, the ECC cell array portion is disposed at a location in which read out speed of data from ECC cell or cells does not become the worst speed in the memory device. Therefore, the worst data read out speed can be measured from outside.

Packaging technology for the NEC SX-3 supercomputers

Abstract: Technological considerations in realizing high-speed supercomputers are presented, focusing on large-scale integrated (LSI) chips, new circuit packaging technology, and a liquid cooling system. The Model SX-1 and SX-2 supercomputers employ a new circuit packaging technology achieving up to 1300 megaflops processing speeds with a 6-ns machine cycle. This new technology features a 1000-gate current mode logic (CML) LSI with 250 ps gate delay as a logic element, a I k bit bipolar memory with 3.5 ns access time for cache memory and vector registers, a 10 cm² multilayer ceramic substrate with thin film fine lines (25- \mu m width, 75- \mu m center-to-center), and a multichip package which contains up to 36 000 logic gates. A liquid cooling module is implemented for highdensity high-efficiency heat-conductive packaging for the arithmetic processor, in addition, high-density high-speed packaging of 64 kbit static metal-oxide semiconductor (MOS) RAM's are used to implement large-capacity fast main memory.

Recyclable shape-memory polymer: Poly(lactic acid) crosslinked by a thermoreversible Diels–Alder reaction

Abstract: An intelligent shape-memory polymer was made through the synthesis of poly(lactic acid) macromonomers with furanyl groups and crosslinking with linkers with maleimidyl groups. The thermoreversible covalent bonds formed by the Diels–Alder reaction between these groups made this polymer recyclable (i.e., environmentally friendly). The structure of the polymer was also studied. A defect of the structure, a dissociated moiety of the thermoreversible bonding, was strongly affected by the reaction conditions and was investigated with UV spectroscopy, which was used to monitor the concentration of the maleimidyl groups. The relation between the flexibility of the linker and the strength and inner stress of the polymer was also evaluated. Reducing the number of defects and relaxing the inner stress were found to increase the strength of the shape-memory polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009