Showing papers by "NEC published in 1997"

Thick GaN Epitaxial Growth with Low Dislocation Density by Hydride Vapor Phase Epitaxy

Abstract: Thick GaN layers were grown by hydride vapor phase epitaxy (HVPE) with the aim of using these layers as a homoepitaxial substrate to improve device quality of laser diodes or light emitting diodes. HVPE is very useful for thick layer growth since the growth rate can reach from several ten up to one hundred micron per hour. In this experiment, the growth began as selective growth through openings formed in a SiO2 mask. Facets consisting of {1101} planes were formed in the early stage and a continuous film developed from the coalescence of these facets on the SiO2 mask. As a result, GaN layers with a dislocation density as low as 6×107 cm-2 were grown on 2-inch-diameter sapphire wafers. These GaN layers were crack-free and had mirror-like surface.

Dual-input image processor for recognizing, isolating, and displaying specific objects from the input images

Abstract: An image processor comprising an image pickup portion to take in an image of an object, a reference point extracting portion that extracts a reference point to be used in object extraction from images taken by the image pickup portion,a corresponding point detecting portion that detects a corresponding point in other images, a three dimensional coordinates value calculating portion that calculates a three dimensional coordinates value of an object by using the absolute position and posture parameters calculated by using image of a reference solid and coordinates values of reference point and corresponding point, a contour point extracting portion that extracts a contour point to show contour of an object on the basis of coordinate values of reference point and three dimensional coordinate values, and an object display control portion that extracts an image of the object from images photographed by the image pickup portion based on coordinates value of contour point and displays it on a display device.

Implementation and performance evaluation of Indirect TCP

Abstract: With the advent of small portable computers and the technological advances in wireless communications, mobile wireless computing is likely to become very popular in the near future. Wireless links are slower and less reliable compared to wired links and are prone to loss of signal due to noise and fading. Furthermore, host mobility can give rise to periods of disconnection from the fixed network. The use of existing network protocols, which were developed mainly for the high bandwidth and faster wired links, with mobile computers thus gives rise to unique performance problems arising from host mobility and due to the characteristics of wireless medium. Indirect protocols can isolate mobility and wireless related problems using mobility support routers (MSRs) as intermediaries, which also provide backward compatibility with fixed network protocols. We present the implementation and performance evaluation of I-TCP, which is an indirect transport layer protocol for mobile wireless environments. Throughput comparison with regular (BSD) TCP shows that I-TCP performs significantly better in a wide range of conditions related to wireless losses and host mobility. We also describe the implementation and performance of I-TCP handoffs.

Semantic and cognition based image retrieval

Abstract: A computer implemented method for searching and retrieving images contained within a database of images in which both semantic and cognitive methodologies are utilized. The method accepts a semantic and cognitive description of an image to be searched from a user, and successively refines the search utilizing semantic and cognitive methodologies and then ranking the results for presentation to the user.

Communication network recoverable from link failure using prioritized recovery classes

Abstract: In a self-healing network, virtual paths between user terminals are classified according to different fault recovery priority levels and communication links are mapped to virtual paths accommodated by the links and to bandwidths remaining in the respective links. Each priority level guarantees a fault recovery with a different amount of network resource. In response to a fault-indicating message identifying a failed virtual path, a search is made through the link-path table for an alternate virtual path and a remaining bandwidth of each link that comprises the alternate virtual path in descending order of the priority classes. In accordance with the priority class of the failed virtual path relative to the priority class of an existing virtual path that shares the same link with the alternate virtual path, a decision is made on whether or not the bandwidth guaranteed by the priority class of the failed virtual path can be allocated to the alternate virtual path from the remaining bandwidth. If the decision is affirmative, the alternate virtual path is established.

Red-eye detection/retouch apparatus

Abstract: In a red-eye detection/retouch apparatus, a first area extraction unit receives an image including a red eye and a signal representing a small area including the red eye and designated by a user and extracts a first area including the red eye. A first pixel selection unit detects the reddest pixel from the first area and outputs coordinate values and color information of the pixel. A determination unit determines whether the other red eye is present on the basis of the signal representing the small area and the coordinate values of the reddest pixel. The determination unit outputs an instruction signal for extracting a second area where the other red eye is present upon determining that the other red eye is present. A second area extraction unit receives the instruction signal and extracts the second area from the first area. A second pixel selection unit detects the reddest pixel from the second area and outputs coordinate values and color information of the pixel. An area expansion unit receives the coordinate values and color information of the pixels and the first area, detects a red-eye area by area expansion, and outputs the red-eye area. An image synthesis unit receives the red-eye area and the image including the red eye and outputs an image whose red-eye area has been corrected to a natural pupil color.

Virtual private network system over public mobile data network and virtual LAN

Abstract: In a virtual private network system accessed by an internet, a virtual local area network (LAN) is connected to a LAN emulation server and IAN emulation clients, and a router is connected between the internet and the virtual LAN. Also, a public mobile data network is connected to a location register and mobile data subscriber processing units, and a data gateway is connected between the internet and the public mobile data networks Further, a virtual private network gateway is connected between the virtual LAN and the public mobile data network. A mobile data terminal having one IP address and one public network address and can be connected to either one of the LAN emulation clients or one of the mobile data subscriber processing units.

Short-channel effect improved by lateral channel-engineering in deep-submicronmeter MOSFET's

Abstract: The normal and reverse short-channel effect of LDD MOSFET's with lateral channel-engineering (pocket or halo implant) has been investigated. An analytical model is developed which can predict V/sub th/ as a function of L/sub eff/, V/sub DS/, V/sub BS/, and pocket parameters down to 0.1-/spl mu/m channel length. The new model shows that the V/sub th/ roll-up component due to pocket implant has an exponential dependence on channel length and is determined roughly by (N/sub p/)/sup 1/4 /L/sub p/. The validity of the model is verified by both experimental data and two-dimensional (2-D) numerical simulation. On the basis of the model, a methodology to optimize the minimum channel length L/sub min/ is presented. The theoretical optimal pocket implant performance is to achieve an L/sub min/ approximately 55/spl sim/60% that of a uniform-channel MOSFET without pocket implant, which is a significant (over one technology generation) improvement. The process design window of pocket implant is analyzed. The design tradeoff between the improvement of short-channel immunity and the other device electrical performance is also discussed.

Large capacity, multiclass core ATM switch architecture

Abstract: A large capacity ATM core switch architecture is disclosed, which supports multiple traffic classes and quality-of-service (QoS) guarantees. The switch supports both real-time traffic classes with strict QoS requirements, e.g., CBR and VBR, and non-real-time traffic classes with less stringent requirements, e.g., ABR and UBR. The architecture also accommodates real-time and non-real-time multicast flows in an efficient manner. The switch consists of a high-speed core module that interconnects input/output modules with large buffers and intelligent scheduling/buffer management mechanisms. The scheduling can be implemented using a novel dynamic rate control, which controls internal congestion and achieves fair throughput performance among competing flows at switch bottlenecks. In the dynamic rate control scheme, flows are rate-controlled according to congestion information observed at bottleneck points within the switch. Each switch flow is guaranteed a minimum service rate plus a dynamic rate component which distributes any unused bandwidth in a fair manner.

Channel engineering for the reduction of random-dopant-placement-induced threshold voltage fluctuation

Abstract: A simple model is proposed, which is able to calculate V/sub TH/ standard deviation due to random dopant placement in the channel, for arbitrary vertical impurity distributions. Substantial decrease in V/sub TH/ fluctuation, while keeping V/sub TH/ the same, is confirmed for low surface impurity channel MOSFETs, in agreement with the model prediction.

Multi-user flash ROM update

Abstract: A system in which a plurality of wireless interface devices, each containing one or more flash memory devices, are interfaced to a server which may be connected in either a wireless or wired LAN by way of a radio link. The system in accordance with the present invention, enables the flash or other type of memory devices in the plurality of wireless interface devices interfaced to the server to be updated over a radio link.

Lens antenna having an improved dielectric lens for reducing disturbances caused by internally reflected waves

Abstract: A lens antenna is disclosed which comprises a conical horn and a lens attached to an aperture of the horn. The lens has a first planar surface at a first side which faces free space and a hyperboloid of revolution at a second side opposite the first side and is made of a dielectric material with relative permittivity ranging from 2 to 4. The lens is provided with a cylindrical portion which has a second planar surface parallel to the first planar surface and displaced from the first planar surface by a predetermined distance. The cylindrical portion being concentric with the lens.

Digital camera recording a reduced image synthesized with a character image of the image picking-up information

Abstract: A reduction processing section ( 10 ) performs a reduction processing for a picked-up image on frame memory ( 7 ). A character image generating section ( 30 ) converts contents of parameter table ( 6 ) and information concerning date, time and picking-up conditions to a character image and store it in a work memory ( 31 ). A synthesis processing section ( 32 ) synthesizes the character image on the work memory ( 31 ) with the reduced image from the reduction processing section ( 10 ). The synthesized simultaneous display reduced image ( 33 ) is stored together with an original image ( 14 ) and a compressed image ( 15 ). Thus, when simultaneous displaying is performed with a application software on a personal computer, an reduced image for use in simultaneous displaying, on which picking-up date, picking-up time and picking-up data are superimposed, is displayed, whereby processing speed for image data retrieval is increased. Moreover, an original image is stored as it is without modifying an initial image.

Card type recording medium, certifying method and apparatus for the recording medium, forming system for recording medium, enciphering system, decoder therefor, and recording medium

Abstract: In a card type recording medium containing a data area where data containing ID information of a holder are recorded, and an image area where image data are recorded, in the image area are recorded second image data which are generated by transforming first image data specifying the holder to frequency-area data, adding the transformed frequency-area data with the ID information and inversely transforming the added data to image signals.

Graphite filaments having tubular structure and method of forming the same

Abstract: A graphite filament which has carbon as a basic structural unit and which have a tubular shape being formed with a helical structure with the carbon hexagons as a main structure and with an outer diameter of 30 nm or less. The tubular lattices a 1 to a 3 are a multiple structure and the interval between inner and outer adjacent tubules is about 0.34 nm, which is similar to the interval between basal planes of graphitic structure. The graphite filament is a new carbon filament material having a structure that is different from a normal graphite filament.

Fault tolerant anonymous channel

Abstract: Previous anonymous channels, called MIX nets, do not work if one center stops. This paper shows new anonymous channels which allow less than a half of faulty centers. A fault tolerant multivalued election scheme is obtained automatically. A very efficient ZKIP for the centers is also presented.

Navigation system using portable phone and navigation method using the same

Abstract: A name and a location of a building within a control area are correlated with a registered phone number. A map covering the control area and its periphery is stored based on the building. The destination building is searched based on the destination and navigation request. A plurality of voice direction messages are stored for directing the navigation. A plurality of question messages are stored for demanding the user to respond according to a predetermined format so as to specify the present location. When the navigation route extends over a plurality of control areas each controlled by a different base station, such information containing the destination, navigation request, present location and route is shared by those different base stations.

Semiconductor package with flexible board and method of fabricating the same

Abstract: Solder balls are attached to a flexible printed-circuit board which is shaped so as to be able to cover at least an upper surface, a side surface, and a lower surface of an IC chip, and the flexible printed-circuit board is placed on the IC chip. Then, the flexible printed-circuit board is folded over edges of the IC chip, and bonded to outer surfaces of the IC chip by an adhesive sheet. Thereafter, a sealing resin is poured into a gap between the upper surface of the IC chip and the flexible printed-circuit board, and cured, thereby completing a semiconductor package.

Organic electroluminescent element having electrode between two fluorescent media for injecting carrier thereinto

Abstract: An organic electroluminescent element has a semi-transparent anode or a semi-transparent cathode inserted between luminescent media for injecting holes thereinto, and the semi-transparent anode or the semi-transparent cathode improves the carrier injecting efficiency so as to enhance the luminance.

Method of generating duobinary signal and optical transmitter using the same method

Abstract: Disclosed is a method for generating a duobinary signal which has the step of: modulating individually an intensity and a phase of a carrier wave. Also disclosed is a duobinary-manner optical transmitter which has: a laser device which outputs signal light; an optical intensity modulator which intensity-modulates the signal light according to a first data signal generated by dividing a data signal into two signals; a precoder which inputs a second data signal generated by dividing the data signal into two signals; and an optical phase modulator which phase-modulates the intensity-modulated signal light according to a signal which is obtained delaying 0.5 bit an output signal of the precoder.

Failure restoration system suitable for a large-scale network

Abstract: In a failure restoration system comprising a distributed hierarchical routing section which is adapted to set up a main path and previously determine an alternate path for the main path in a network, an alternate path selection section is adapted to obtain complete source route information for the main path when it attempts to set up the main path. The alternate path selection section adds the complete source information to a SETUP signaling message for setting up the alternate path, thereby provides a physical alternate path as much different as possible from the main path.

Structure for bonding semiconductor device to substrate

Abstract: Au bump is provided on an Al pad of a semiconductor chip. Substrate pads are arranged at predetermined pitches on a circuit board. In each substrate pad, the length (L) of a first side parallel to the array direction is shorter than the length (M) of a second side which is orthogonal to the first side. The substrate pads are formed so that the length (L) of the first side is smaller than the diameter of the Au bump and the length (M) of the second side is larger than the diameter of the Au bump. A solder bump is formed on each substrate pad and it melts to cover the Au bump. At the time of bonding, the width of the solder bump in the direction parallel to the first side is smaller than the diameter of the Au bump, and the width thereof in the direction parallel to the second side is greater than the diameter of the Au bump.

Print system managing the security of a printer shared on a network

Abstract: Authority of each user to use a printer is set in a security data base with respect to the number of sheets to be printed, kinds of sheets, and special printing functions. A print request, including the number of sheets to be printed, the kinds of sheets, and whether special printing functions are to be used are sent to a security validating device, and the security validating device decides whether authorization to use the printer is to be granted based on the restrictions on the user maintained in the data base and the status of the user. If printing is authorized, after the printing is completed, an editing device updates information on the status of use in the security data base.

An apparatus for a synchronized playback of audio-video signals

Abstract: An apparatus for producing synchronized playback of compressed digital data of audio-video signals from a desired portion of the digital data. The apparatus can be used in a system having comparatively low data processing ability, and work independent of the resolution of a software timer of the system. The apparatus comprises a frame counter for obtaining a reference time indicating reproduction time passage of the audio signal component from a reproduced data amount of the audio signal component. A delay detector detects progress of the video signal component in reference to the reference time.

Learning personal preferences on online newspaper articles from user behaviors

Abstract: This paper discusses methods by which user preferences for WWW-based newspaper articles can be learned from user behaviors. Two modes of inference were compared in an experiment: one using explicit feedback and the other using implicit feedback. In the explicit feedback mode, the users score all articles according to their relevance. In the implicit feedback mode, the user reads articles by performing scrolling and enlarging operations, and the system infers from the operations how much the user was interested in each article. Our newspaper on the WWW, called ANATAGONOMY, has a learning engine and a scoring engine on the server. The system users read daily news articles by using a WWW browser in which there is an interaction agent that monitors the user behaviors. The learning engine on the server infers user preferences from the interaction agent, and the scoring engine scores new articles and creates personalized newspaper pages based on the extracted user profiles. In an experiment, the system was able to personalize the newspaper to some extent when using only implicit feedback when some parameters were properly set, but the personalization was not as precise as it was when explicit feedback was used. By mixing explicit feedback with implicit feedback, the system could personalize newspapers quickly and precisely without requiring too much effort on the part of the users. User preferences can also be used to construct information retrieval agents or even to create cyberspace communities of the users that have similar interests. We think that the proposed technique for learning user preferences greatly enhances the value of the WWW.