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.

Self-healing network with distributed failure restoration capabilities

Abstract: In the event of a failure on a transmission line, a sender, or a terminal node of the failed line, broadcasts CONTROL packets to each of all adjacent tandem nodes, containing a hop count and node trace data. In response to a CONTROL packet, each tandem node increments the hop count of the packet, updates its node trace data, makes a record of all arriving CONTROL packets, and broadcasts copies of each arriving CONTROL packet to adjacent nodes if the hop count is smaller than a prescribed value. A chooser, which is the other terminal node of the failed line, responds to CONTROL packets from a given node for sending back to the given node as many RETURN packets as there are failed channels. Each tandem node makes a record of all arriving RETURN packets, checks the node trace data of each RETURN packet against that of the CONTROL packets in the record to detect if there is a spare channel to an adjacent node on a route to the sender with a least hop count, transmits each RETURN packet to it if a spare channel is detected, or causes retransmission of a RETURN packet from the chooser to another tandem node if no spare channel is detected. The sender responds to each RETURN packet by switching a link from a failed channel to a spare channel indicated by the packet. An END packet is sent back from the sender to each tandem node along which the RETURN packet travelled between the chooser to the sender. On reaching the chooser, the END packet is used to switch a link from a failed channel to a spare channel indicated by the received END packet.

Diameter-selective resonant Raman scattering in double-wall carbon nanotubes

Abstract: Double-wall carbon nanotubes (DWNT's) have been studied by Raman scattering using different excitation wavelengths and their spectra compared to those of single wall nanotubes (SWNT's) and ${\mathrm{C}}_{60}$-SWNT peapods. Raman scattering from the radial and tangential vibrational modes of very small diameter $d\ensuremath{\sim}0.6--0.9 \mathrm{nm}$ secondary (interior) semiconducting tubes within the DWNT can be unambiguously identified with 647.1 and 1064 nm excitations. The frequency of the tangential displacement vibrational modes identified with these secondary (interior) tubes is found to be downshifted by $\ensuremath{\sim}7 {\mathrm{cm}}^{\ensuremath{-}1}$ relative to that of the larger primary (exterior) tubes that exhibit a diameter $d\ensuremath{\sim}1.3--1.6 \mathrm{nm}.$ This downshift strongly suggests that at small tube diameters (i.e., $d\ensuremath{\sim}0.7 \mathrm{nm}),$ the associated wall curvature of the nanotube may require an admixture of ${\mathrm{sp}}^{3}$ character in the C-C interaction. Our results also show that the value ${\ensuremath{\gamma}}_{0}=2.90 \mathrm{eV}$ for the nearest C-C tight binding integral is consistent with the resonant enhanced Raman scattering from DWNT's.

Zone registration of a mobile in a mobile telephone system

Abstract: In a service area of a mobile telephone system, there are plural base radio stations. A mobile radio station in the service area broadcasts a request signal of zone registration. All the base stations in the service area receive this request signal, measure the field intensity of the signal, and transmit the value of the measured intensity to the mobile radio station. The mobile radio station transmits a response signal to a base radio station where the field intensity is the highest. This response signal is reported to a radio channel control unit where the contents of the zone register is revised in accordance with the reported response.

Reconfigurable device having programmable interconnect network suitable for implementing data paths

Abstract: A reconfigurable device includes a plurality of function cells and a programmable interconnect network which programmably connects the function cells. The programmable interconnect network includes horizontal programmable interconnect ways and vertical programmable interconnect ways. Each horizontal programmable interconnect way includes a short horizontal programmable interconnect channel and a long horizontal programmable interconnect channel, and each vertical programmable interconnect way includes a short vertical programmable interconnect channel and a long vertical programmable interconnect channel. In the horizontal programmable interconnect way, both the short horizontal programmable interconnect channel and the long horizontal programmable interconnect channel are constructed to have “shift structure”, thereby “sector segmentation” and problems related to the sector segmentation are avoided. The function cells are directly connected to the short horizontal programmable interconnect channel, but are not directly connected to the long horizontal programmable interconnect channel, therefore, signal transfer of input/output signals between the function cell and the long horizontal programmable interconnect channel is conducted necessarily through the short horizontal programmable interconnect channel and a programmable switch, thereby load capacitance on the long horizontal programmable interconnect channel is reduced and thereby high-speed signal transfer is realized.

An Exact Algorithm for Selecting Partial Scan Flip-Flops

Abstract: We develop an exact algorithm for selecting flip-flops in partial scan designs to break all feedback cycles. The main ideas that allowus to solve this hard problemexactly for large, practical instances are - graph transformations, a partitioning scheme used in the branch and bound procedure, and pruning techniques based on an integer linear programming formulation of the minimum feedback vertex set (MFVS) problem.We have obtained optimum solutions for the ISCAS '89 benchmark circuits and several production VLSI circuits within reasonable computation time. For example, the optimal number of scan flip-flops required to eliminate all cycles except self-loops in the circuit s38417 is 374. This optimal solution was obtained in 32 CPU seconds on a SUN Sparc 2 workstation.