Abstract: An object of the present invention is to provide a method for manufacturing a glass particle deposited body in which a taper portion formed at an end portion of the glass particle deposited body is reduced without increasing the number of burners.

Abstract: A method of manufacturing an optical fiber preform and an optical fiber at a lower cost than conventional manufacturing methods, and an optical fiber produced by such method. A soot glass deposit body is produced such that the diameter D of a crude preform, which is made by consolidating the soot glass deposit body, satisfies the expression 0.95 J?D (whereas, D?J) relative to the cladding diameter J of an optical fiber preform, the cladding diameter J being determined by the diameter and the refractive index of the core of the crude preform. Subsequently, an optical fiber preform is made by modifying the diameter D of the crude preform so as to coincide with J. Such modification is done by reducing the diameter of the crude preform or by depositing additional fine glass particles. The crude preform on which additional fine glass particles are deposited is treated as an optical fiber preform in a state as it is, and drawn into an optical fiber.

Abstract: A method can stably produce a high-quality glass-particle-deposited body by depositing glass particles in an intended state, and a burner synthesizes glass particles. The method uses a burner comprising a material-gas-feeding pipe at its center. In one aspect of the method, while glass particles are synthesized with the burner to be deposited, the magnitude of bending at the tip of the material-gas-feeding pipe is maintained at a value of at most 1.2 mm. In another aspect, while glass particles are synthesized with the burner to be deposited, the magnitude of bending at the bottom end of the material-gas-feeding pipe is maintained at a value of at most 0.3 mm. Another burner for synthesizing glass particles comprises a material-gas-feeding pipe and a plurality of gas-feeding pipes for feeding gases needed to form a flame. In this burner, in at least one combination of neighboring two pipes among these pipes, the two pipes are mutually linked at a plurality of longitudinal locations.

Abstract: The present invention discloses a tunnel-redirection device used as a packet transfer device, in which user can transmit a packet via a plurality of network tunnels simply through the management of a single network tunnel. The tunnel-redirection device 10 switches a packet on a first network tunnel A arranged between a user terminal 1 and a WWW server 3a and a DNS server 3b installed as a center of the provider on Internet 3, arranges a second network tunnel B between the system and a contents server ISP1 of the provider installed in a region “a”, extracts a packet from the user terminal on a first network tunnel to a contents server ISP1, converts said packet to a packet of the second network tunnel, transfers said packet to the contents server ISP1, converts said packet from the contents server on the second network tunnel to the user terminal to a packet of the first network tunnel, and transfers said packet to the user terminal.

Abstract: To provide a method for producing a glass particle deposit and a method for producing a glass preform, in which outer diameter variation of the glass particle deposit can be reduced to thereby improve quality. A flow rate of clean gas (CG) introduced into a container potion 10 is limited to thereby prevent the outermost layer of a glass particle deposit 20 from being locally cooled and reduce variation in bulk density in the longitudinal direction of the glass particle deposit 20, that is, outer diameter variation and breakage.

Abstract: The present invention relates to the rate control system of a TCP layer in communications conducted between terminals 1 and 3 via a base station 2 using a wireless link. An object of the present invention is to avoid the fruitless reduction of throughput in communications conducted via a wireless link. If the discard of a packet transmitted from the base station 2 to the terminal 3 via a wireless link is detected when the packet is transmitted from the terminal 1 to the terminal 3, the base station or terminal 3 is provided with means for notifying the terminal 1 of a wireless packet discard using a TCP layer. The terminal 1 is configured in such a way that if the wireless packet discard notification is received, a TCP layer control unit 10 does not exercise slow-start control at the time of re-transmission and re-transmits the discarded packet at a rate adopted before the reception of the notification.

Abstract: To provide an apparatus for manufacturing a glass particles deposit in which it is possible to effectively prevent the foreign matter from being deposited on or mixed into the glass particles deposit during the manufacturing operation. The apparatus for manufacturing the glass particles deposit comprises an upper funnel, a reaction vessel and a lower funnel, wherein the glass particulates are deposited around the outer circumference of a starting rod supported by a support rod within the reaction vessel while the starting rod is being rotated around its axis and reciprocated up and down, characterized in that a sleeve made of quartz separating an inner wall of the reaction vessel and a central rotation member is installed inside the reaction vessel.

Abstract: The present invention provides a method for manufacturing a glass particles deposit body that is formed on the periphery of a starting rod by an OVD method, whereby an optical fiber with enhanced optical transmission characteristics can be produced by reducing the number of disconnections and preventing the alien substances from being mixed into the glass particles deposit body. This invention involves the use of the OVD method in which (1) before or after starting to deposit fine glass particles, a reaction vessel is enclosed to suck and exhaust a gas within the reaction vessel after a removal operation of deposited fine glass particles from the inside of the reaction vessel, (2) when not in operation, a purge gas is passed at a flow rate of 1 m/min or more through each gas line of a burner, (3) when not in operation, a clean air (CA) is introduced into the reaction vessel to make the inner pressure of vessel positive, or (1) and (2) or (1), (2) and (3) are combined.

Abstract: In a method for manufacturing a glass preform through a heating process of heating a glass particles deposit including a clad partially while moving it successively in a longitudinal direction to form the glass particles deposit, and vitrifying the glass particles deposit to form the glass preform, wherein a chlorine based gas is preferably included at least in the atmosphere of a furnace tube 2 to vitrify the glass preform 9 in the process of heating the glass particles deposit while moving at least the glass particles deposit upward or downward, using a lift 7 for traversing the glass particles deposit (glass preform 9) upward or downward throughout the process.

Abstract: A method and an apparatus for producing a glass preform having a uniform J ratio by adjusting the weight of glass particles to be deposited on a starting glass rod. The method uses an OVD method by which glass particles are successively deposited on an external cylindrical surface of a starting glass rod to create a growing soot layer thereon and the soot layer is then vitrified into a transparent glassy body, wherein the glass particle deposition is conducted by adjusting an amount of glass particles to be deposited based on data of J ratio fluctuations (where the J ratio is a ratio of an outer diameter of a glass preform to an outer diameter of a starting glass rod) of a previously produced glass preform in its longitudinal direction so that the glass preform to be produced can attain a uniform J ratio in its longitudinal direction.

Abstract: A re-calculator circuit obtains the MCR value of each connection stored in an MCR storage unit, and performs a calculation in such a way as to impartially distribute the available rate band of a FIFO among active connections. The re-calculator circuit stores a rate band attached to the MCR value of each active connection by this calculation, in a virtual MCR storing unit as a virtual MCR value. This rate measurement unit refers to the virtual MCR value stored in the virtual MCR storage unit, and judges whether or not the input cell rate of each active connection exceeds the virtual MCR value. This result is inputted to an input control unit. The input control unit examines the input cell rate information and congestion monitoring information inputted from a queue length monitor unit for monitoring the volume of cells buffered in the FIFO, and determines whether to discard the incoming cell or to input the cell to the FIFO.

Abstract: The present invention relates to a buffer control apparatus and method.

Abstract: A drawing apparatus 1 has a drawing furnace 11 for heating and drawing an optical fiber preform 2, and a carbon heater 13 is disposed in this drawing furnace 11. The carbon heater 13 has a heating portion the length of which in a drawing direction is set to not less than 280 mm. The carbon heater 13 heats the preform so that a maximum temperature on the surface of the optical fiber preform 2 in the drawing furnace 11 becomes below 1800° C. The optical fiber preform 2 is drawn in a state in which the temperature of the muffle tube 12 of the drawing furnace 11 is kept below 1800° C., so that atomic arrangement in the optical fiber preform 2 becomes relatively aligned in a state of reduced randomness of atomic arrangement. This permits the optical fiber 3 to be drawn as reflecting the reduced randomness state of atomic arrangement, whereby the optical fiber 3 can be obtained with reduced Rayleigh scattering intensity and lowered transmission loss.

Abstract: A data transmission apparatus is provided for transmitting data received from a user terminal device through a plurality of networks to a destination, the user terminal device executing communication using an Internet protocol. The data transmission apparatus includes a routing table storing information relating a destination address of the data and addresses of the plurality of networks; an information table storing static and dynamic information about the plurality of networks; and a selection unit selecting one or the plurality of networks, through which the data transmission apparatus transmits the data to the destination, based on the static and dynamic information. The data transmission apparatus enables data transmission through the appropriate network by selecting the appropriate network based on the static and dynamic information about the plurality of networks.

Abstract: In a first UPC, a PCR is set as a monitor rate for each connection. If a transfer rate of a cell exceeds the PCR set for the connection, the cell is discarded. In a second UPC, an ACR is set as a monitor rate for each connection. If the transfer rate of the cell exceeds the ACR set for the connection, a lower priority is assigned to that cell. Additionally, with a configuration where one UPC monitors a varying rate, a parameter change process is controlled by obtaining a time between a passage time of a detected B-RM cell and an arrival of a user cell and comparing the obtained time with maximum and minimum delay standard values. A parameter table including some parameters is provided. A header of an arrived cell in a forward direction is extracted, and it is determined whether or not the arrived cell is a violation cell using the leaky bucket algorithm, etc. If the arrived cell is a violation cell, it is discarded.

Abstract: A method for producing a glass preform by synthesizing a porous glass preform by a vapor-phase synthesizing method and heating said porous glass preform in a vacuum or reduced-pressure atmosphere so as to consolidate said porous glass preform, which comprises the steps of: a first step of degassing said porous glass preform to thereby remove gas adsorbed or contained therein; a second step of temporarily contracting said porous glass preform at a temperature higher than a temperature in the first step and lower than a consolidation temperature; and a third step of consolidating said porous glass preform at the consolidation temperature; the degassing of said first step is determined in accordance with the bulk density of said porous glass preform.

Abstract: A cell assembly and multiplexing device includes short cell assembly parts which store input information received via respective input lines and add short cell headers to the input information so that short cells having the short cell headers are assembled, and a multiplexing part which arranges the short cells in given fields of standard cells having a given standard format and a fixed cell length and outputs the standard cells having the short cells to a transmission line.

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.