Abstract: A data distribution system capable of suppressing a fall of the efficiency of operation of a network due to repeated data retransmission in the network when distributing a large volume of data from a data distribution server on a data provider side to a data receiver side access server via the network. This data distribution system is comprised by a data distribution server, an access server for transferring intended data to each user, and a network cache apparatus provided in the network and having a cache function unit for temporarily storing the data from the data distribution server and an exchange function unit for routing the stored data to the access server corresponding to the destination user.

Abstract: In addition to the configuration of a conventional optical XC node, a former-stage regenerator for converting optical signals to electrical signals and regenerating optical signals again is provided at an output stage of a demultiplexer and at the input stage of an optical switch unit. Since the regenerator has a 3R function, the regenerator compensates for the influence of the noise and crosstalk generated during propagation in the transmission line, and improves the S/N ratio of the optical signals. Since the optical signals with S/N ratios improved in this way are inputted to the optical switch unit, it is sufficient only if a latter-stage regenerator compensates for the S/N ratio degradation generated in the optical switch unit, and thereby the error rate characteristic of the optical signals can be improved.

Abstract: A protection switch comprising a demultiplexer, optical selector, a multiplexer, and a monitor circuit is provided on the input side and the output side of an optical XC node. The demultiplexer demultiplexes the wavelength-multiplexed optical signals of a 0-system and a 1-system, and transmits these optical signals to the optical selectors which are provided for the respective wavelengths. The optical selectors are controlled by the monitor circuit, and switch the optical signal of one system to that of the other system when a fault occurs. The optical signals of the respective wavelengths outputted from the optical selectors are multiplexed by a multiplexer to be transmitted. The demultiplexer and the multiplexer can be differently arranged depending on the configuration of a transmission line or the optical XC node. Further, a multi-wavelength selection filter such as an acousto-optical filter or the like can be used as a protection switch.

Abstract: Disclosed herein is an optical cross-connect device including first wavelength demultiplexing sections each for demultiplexing WDM (wavelength division multiplexed) signal light into a plurality of optical signals, wavelength group generating sections each for receiving the optical signals from each first wavelength demultiplexing section to generate wavelength groups, first wavelength multiplexing sections each for receiving each wavelength group from each wavelength group generating section to output a WDM wavelength group, a routing section for routing the input WDM wavelength groups, second wavelength demultiplexing sections each for receiving each WDM wavelength group from the routing section to output a wavelength group having a plurality of wavelengths, wavelength converting sections each for performing wavelength conversion of each optical signal of the wavelength group output from each second wavelength demultiplexing section, and second wavelength multiplexing sections each for wavelength division m

Abstract: An optical switch has first to fourth optical matrix switches in each of which a plurality of 2-input/2-output optical switch elements are arranged in a matrix to form a plurality of input ports, a plurality of auxiliary input ports, a plurality of output ports, and a plurality of auxiliary output ports. The auxiliary output ports in the first optical matrix switch are connected to the respective input ports in the third optical matrix switch, the output ports in the second optical matrix switch are connected to the respective auxiliary input ports in the third optical matrix switch, the output ports in the first optical matrix switch are connected to the respective auxiliary input ports in the fourth optical matrix switch, and the auxiliary output ports in the second optical matrix switch are connected to the respective input ports in the fourth optical matrix switch.

Abstract: The present invention aims at providing an optical switch changeover controlling method, an optical node device and an optical switch system, capable of avoiding an interruption in an optical output power when changing over an optical path making use of a spatial optical switch arranged with a plurality of optical switch elements. To this end, the optical switch changeover controlling method according to the present invention enables an uninterrupted changeover of an optical path by conducting a reconnection of the optical path after establishing a state where the optical path before the changeover and the optical path after the changeover are simultaneously set concerning the spatial optical switch within the optical node device, when conducting a changeover of the optical path so as to transmit a client optical signal having been transmitted through a working ray path to a protective ray path such as in a case that a fault occurs in the working ray path.

Abstract: The present invention aims at providing an optical switch network of lower loss, lower cost, downsized and superior expandability. To this end, one configuration of the optical switch network according to the present invention comprises a plurality of input ports, a plurality of output ports, a plurality of wavelength converting means provided corresponding to the plurality of input ports, respectively, for each converting a wavelength of light input from each of the input ports, and selecting means for outputting output lights from the plurality of wavelength converting means to particular ports of the output ports, respectively, corresponding to the wavelengths of the output lights. The optical switch network having such a configuration is free of provision of optical branching/coupling devices, therefore it is possible to achieve lower loss, downsized and superior expandability, as compared with conventional distributing and selecting type optical switch networks.

Abstract: The present invention,is directed to an optical space switch accommodating a plurality of input light paths and output light paths. The optical space switch comprises a plurality of polarization control optical switches, each consisting essentially of: polarization control means having elements, one for each input light path, for rotating through 90° the polarizing direction of light information incident from each input light path or otherwise retaining the polarizing direction thereof for output; and a light path routing element for routing the light path for the light information output from the polarization control means in accordance with the polarizing direction of the light information. These polarization control optical switches are arranged in a matrix pattern or coupled in cascade to implement a polarization control optical space switch.

Abstract: If an optical switch unit configuring an optical switch is implemented by a three-stage circuit, optical amplifiers are arranged on the input and output sides of an optical space switch in a first stage, and the optical space switch and the optical amplifiers on both of the input and output sides are used as an expansion unit for expanding a switching capacity. Similarly, optical amplifiers are arranged on input and output sides of an optical space switch in a third stage, and the optical space switch and the optical amplifiers on both of the input and output sides are used as an expansion unit for expanding a switching capacity. Accordingly, there is no need to arrange extra optical amplifiers even at an initial setting when only part of a maximum switching capacity is used, thereby reducing an initial investment.

Abstract: The present invention is directed to an optical space switch accommodating a plurality of input light paths and output light paths. The optical space switch comprises a plurality of polarization control optical switches, each consisting essentially of: polarization control means having elements, one for each input light path, for rotating through 90.degree. the polarizing direction of light information incident from each input light path or otherwise retaining the polarizing direction thereof for output; and a light path routing element for routing the light path for the light information output from the polarization control means in accordance with the polarizing direction of the light information. These polarization control optical switches are arranged in a matrix pattern or coupled in cascade to implement a polarization control optical space switch.

Abstract: An optical transmission system includes an optical path cross-connect device and an electrical cross-connect device connected by a plurality of working and standby input/output interface links. Optical signals in the working and standby systems are entered from the optical path cross-connect device into the electrical cross-connect device via the working and standby interface links, respectively, and switching of working and standby transmission lines is performed electrically by the electrical cross-connect device without momentary disconnect.

Abstract: Source data is stored in a source data storage unit and a comparing device compares source data with destination data stored in a destination data storage unit. A destination address compressing unit compresses destination address information, and other accounting parameters are output with some delay. An accumulating device accumulates information from the destination address compressing unit as an address. A source address compressing unit compresses or delays information from an accumulating unit, and then outputs information. A source address carrier compressing unit compresses or delays information from the source address compressing unit, and then outputs information. A destination address source address carrier re-compressing unit compresses or delays compressed information from the source address carrier compressing unit, and then outputs information. A period abnormality detecting circuit in an accounting unit validates transfer data and prevents a wrong accounting process from being performed.

Abstract: An ATM connection is a virtual communication path specified by VPI/VCI. A plurality of ATM connections that are directed to the same output line is defined as an ATM connection group. A connection UPC (Usage Parameter Control) facility is provided for each of the ATM connections and a connection group UPC facility is provided for the ATM connection group. The connection UPC facilities and the connection group UPC facility are operated in either the monitor mode or the control mode. In the monitor mode, when the rate of flow of packets into a network exceeds a threshold, a control unit is informed of it, but cells are allowed to enter the network as they are. In the control mode, when the rate of flow of cells into the network exceeds the threshold, cells the flow rate of which exceeds the threshold are discarded.

Abstract: An improved electrode for an alkaline storage battery can suppress the reduction of the battery capacity when the battery is used in a high-temperature environment. The electrode is formed by charging or filling a collector, which consists of a porous body of a nickel-boron alloy containing 0.001 to 3 percent by weight of boron, with an active material. The porous body of the nickel-boron alloy can be formed by depositing nickel on a surface of a substrate consisting of a porous polymer by electroless plating with a boron compound serving as a reductant.

Abstract: In combination with a diesel engine, a particulate trap for purifying the diesel exhaust of the engine includes a case provided in the exhaust line of the diesel engine and a filter element mounted in the case. The filter element is a porous member of a heat-resistant metal framework having the form of a three-dimensional mesh. The surface roughness of the metal framework is at least 0.2 .mu.m. The pores of the porous member have an average diameter of 0.1-1 mm, the average number of such pores as counted in the thickness direction of the porous member is 10 or more, the volume packing density of the filter element to the entire filtering space is 10-40%, and the filter has a gas inflow filtration area of 400 cm.sup.2 per liter of the displacement of the engine to which the trap is to be mounted. The filter element has a high capacity to collect particulates and can withstand thermal shock during regeneration and yet produces little pressure drop in the exhaust line during filtration.