Kokusai Denshin Denwa Kabushiki Kaisha

Mitsubishi Heavy Industries Limited

Pebble Bed Modular Reactor (pty) Limited

Other

Pebble Bed Modular Reactor Limited

Noriyuki Takeda

Hidenori Taga

Shigeyuki Akiba

Shu Yamamoto

Noboru Edagawa

Masatoshi Suzuki

Shoichi Doi

Hideaki Tanaka

Koji Goto

Shinichi Nakagawa

Takayuki Miyakawa

To provide a connecting structure of a double tube and an assembling or disassembling method of the double tube capable of disassembling or repairing an inner tube without cutting an outer tube. A connecting structure (A) includes an outer tube () and an inner tube (). The outer tube () is provided at a location corresponding to a connection flange portion () of the inner tube () with an outer tube short cylinder () including openings () each having a lid (). The outer tube short cylinder () is provided at respective ends with outer tube connection flange portions (A andB). There are provided push-up bolts () capable of adjusting gaps respectively between an outer tube connection flange portions (A-andA-) which are opposed to each other, and between an outer tube connection flange portions (B-andB-).

Connecting structure of a double tube

A double pipe apparatus that includes an outer pipe and an inner pipe inserted into the outer pipe, and regulates a flow of a gas flowing through the double pipe apparatus. The double pipe apparatus includes a flow regulating valve, a valve stem which which penetrates the outer pipe and the inner pipe, and fluid leakage preventing parts including a bellows which is provided between the outer pipe and the inner pipe and which prevents the gas from leaking outside the outer pipe. One end of the bellows is attached to an inner wall of the outer pipe, and the other end of the bellows is attached to a flange formed on the valve stem, so that the gas flowing through the inner pipe is prevented from leaking outside the outer pipe.

Double pipe apparatus

An object of the present invention is to realize almost the same transmission characteristic in all wavelengths at a transmission rate of 10 Gb/s or more. An optical transmitter outputs WDM signal light multiplexed with signal light of a plurality of wavelengths toward an optical transmission line . The optical transmission line comprises an optical transmission fiber , an optical repeating amplifier and a dispersion compensating fiber . The gain characteristic of the optical repeating amplifier is set so that the gain becomes the maximum at the effective zero dispersion wavelength of the optical transmission line and that lowers inversely proportional to the distance from the effective zero dispersion wavelength. The whole optical transmission line is set so that the peak power deviation between the effective zero dispersion wavelength &lgr;0 and the wavelength &lgr;1 or &lgr;n on both end becomes approximately 4 dB.

WDM optical transmission system and an optical transmission line thereof

An equalizing apparatus for equalizing gains of wideband wavelength-division multiplexed light and for improving the S/N ratio comprises a plurality of optical amplifyer for optically amplifying light in different wavelength groups, respectively; and multiplexer for multiplexing optically amplified light from said plurality of optically amplifying means.

Gain equalizing apparatus

This invention provides the gain equalizer positioned to an optical amplifying transmission line for equalizing gains of said optical amplifying transmission line, comprising a plurality of first optical filters varying transmittance periodically in at least predetermined wavelength range, and one or more second optical filters that their transmittance peaks at a wavelength substantially coinciding to the predetermined transmittance bottom wavelength of the first optical filters and decreases in a predetermined range at both side of the predetermined transmittance bottom wavelength.

Gain equalizer and optical amplifying transmission line

Wavelength multiplexed optical signals which are input into a first optical amplifier from an optical transmission terminal device over an optical fiber are differently amplified in respective wavelengths due to unevenness of gain of the optical amplifiers and then output. By providing M-transmission optical filters having an M-type transmission characteristic to cancel gain deviation of the optical amplifiers in respective wavelengths, a flat gain characteristic can be achieved even after the optical signals are transmitted via a plurality of optical amplifiers and a plurality of M-transmission optical filters. Also, by removing ASE in a wavelength range of 1.53 .mu.m which prevents signal amplification in a wavelength range of 1.55 .mu.m, the wavelength multiplexed optical signals which are sufficiently amplified can be transmitted to an optical reception terminal device over the optical fiber.

Optical transmission line

A wavelength division multiplexed (WDM) optical communication method and apparatus uses a pre-emphasis technique to adjust the attenuation or amplification of a particular optical channel at a transmitter terminal to produce identical signal-to-noise ratios for all of the optical channels at a receiver terminal. The pre-emphasis adjustments to the transmitted signals are made on the basis of signal-to-noise ratio measurements performed at the receiver terminal. The signal-to-noise ratio values for each channel are transmitted through a facing line that is also used to transmit data along optical communication lines from the receiver terminal back to the transmitter terminal. The present invention also provides a method and apparatus for monitoring optical transmission paths for the deterioration of optical amplifier repeaters or an optical fiber. The optical signals are then adjusted to account for the location of the particular amplifier or fiber that has deteriorated.

WDM optical communication method with pre-emphasis technique and an

The present invention provides a wavelength division multiplexed optical fiber transmission equipment which can increase the number of channels of the WDM signal by reducing a required bandwidth of optical signals while suppressing an interference between signals caused by four-wave mixing. A WDM optical transmitting terminal comprises five or more optical transmitters and the wavelengths of optical signals from the optical transmitters are set such that the spacing between the wavelengths of two signals is re-used as the spacing between the wavelengths of other two signals separated by the above signals by two or more waves and there is no periodicity in the channel spacing s. For instance, the wavelengths of the optical signals are set as shown in FIG. 1. As the result, deterioration in the transmission characteristics of the optical signals can be effectively reduced and, at the same time, the maximum number of channels of the WDM signal can be increased. To the WDM optical transmitting terminal is added polarization state controllers for controlling the state of polarization such that the states of polarizations of adjacent signals cross each other at an output of the WDM optical transmitting terminal.

Wavelength division multiplexed optical fiber transmission equipment

It is the object of the present invention to optimize the degradation due to the four-wave mixing of wavelength multiplexed signals and the distortion due to the chromatic dispersion, thereby to provide a wavelength division multiplexed optical fiber transmission equipment having good transmission characteristics. A WDM transmitting terminal consists of four transmitters of channels 1 to 4, and a wavelength-division multiplexer. Further, a WDM receiving terminal consists of an equalization optical fiber, a wavelength-division demultiplexer, and four receivers of the channels 1 to 4. The WDM transmitting terminal and the WDM receiving terminal are interconnected by transmission optical fibers and an optical amplifier. The equipment is designed so that the wavelengths .lambda..sub.1, .lambda..sub.2, .lambda..sub.3 and .lambda..sub.4 of the optical signals output from the transmitters all lie on the short-wavelength side with respect to the average zero-dispersion wavelength .lambda..sub.0. This allows the distortion due to the four-wave mixing of a wavelength multiplexed signal to be reduced. The equalization optical fiber has a chromatic dispersion of a sign opposite to the chromatic dispersion of the optical fibers forming a transmitting path, thereby for compensating the chromatic dispersion of the optical signals output from the transmitters.

Growing community of inventors

Tokyo, Japan

Noriyuki Takeda