Abstract: An optical fiber vibration sensor includes a light source, an optical receiver, an optical dividing/coupling part, a signal processing unit, and a fiber loop part made of an optical fiber. A part of an optical fiber composing the fiber loop part is installed outside a housing of a main body of the optical fiber vibration sensor and another part of the optical fiber composing the fiber loop part is installed outside the housing as a vibration detecting optical fiber.

Abstract: A high-strength steel plate includes the following composition: 0.18 to 0.23 mass % of C; 0.1 to 0.5 mass % of Si; 1.0 to 2.0 mass % of Mn; 0.020 mass % or less of P; 0.010 mass % or less of S; 0.5 to 3.0 mass % of Ni; 0.003 to 0.10 mass % of Nb; 0.05 to 0.15 mass % of Al; 0.0003 to 0.0030 mass % of B; 0.006 mass % or less of N; and a balance composed of Fe and inevitable impurities. A weld crack sensitivity index Pcm of the high-strength steel plate is 0.36 mass % or less. The Ac3 transformation point is equal to or less than 830° C., the percentage value of a martensite structure is equal to or greater than 90%, the yield strength is equal to or greater than 1300 MPa, and the tensile strength is equal to or greater than 1400 MPa and equal to or less than 1650 MPa. A prior austenite grain size number N? is calculated by N?=?3+log2m using an average number m of crystal grains per 1 mm2 in a cross section of a sample piece of the high-strength steel plate.

Abstract: This wear-resistant steel plate includes, in terms of mass %, C: not less than 0.13% and not more than 0.18%, Si: not less than 0.5% but less than 1.0%, Mn: not less than 0.2% and not more than 0.8%, P: not more than 0.020%, S: not more than 0.010%, Cr: not less than 0.5% and not more than 2.0%, Mo: not less than 0.03% and not more than 0.30%, Nb: more than 0.03% but not more than 0.10%, Al: not less than 0.01% and not more than 0.20%, B: not less than 0.0005% and not more than 0.0030%, and N: not more than 0.010%, with a remainder being Fe and unavoidable impurities, wherein an element composition is such that HI is 0.7 or greater and Ceq exceeds 0.50, and an HB value (Brinell hardness) at 25° C. is not less than 360 and not more than 440.

Abstract: A high-tensile steel plate of low acoustic anisotropy and high weldability having yield stress of 450 MPa or greater and tensile strength of 570 MPa or greater and a process for producing the steel plate are provided. The steel has an Si content of 0.10% or less, thereby achieving a volume ratio of island martensite of 3% or less, contains Nb?0.025% and Ti?0.005% so as to satisfy 0.045%?[Nb]+2×[Ti]?0.105%, contains Nb, Ti, C and N in ranges such that the value of A=([Nb]+2×[Ti])×([C]+[N]×12/14) is 0.0022 to 0.0055, and has a steel structure wherein bainite volume ratio is 30% or more and pearlite volume ratio is less than 5%.

Abstract: The present invention provides a high tension steel plate of a tensile strength of 570 MPa or more with a small acoustic anisotropy and with excellent weldability tensile strength and a method of production of steel plate predicated on the high productivity accelerated cooling stop process, which steel sheet is a high tension steel plate with a value of 0.045%?Nb+2Ti?0.105%, A=(Nb+2Ti)×(C+N×12/14) satisfying 0.0025 to 0.0055 and with a steel composition containing bainite in an amount of 30 vol % or more and pearlite+martensite-austenite constituent (MA) in an amount of less than 5 vol %. The steel is heated to 1200° C. or more, rough rolled at 1020° C. or more, then rolled at a cumulative reduction rate from over 920° C. to less than 1020° C. of 15% or less and a cumulative reduction rate from 860 to 920° C. of 20 to 50%, then starting accelerated cooling giving a cooling rate of 2 to 30° C./sec at 800° C. or more, stopping the accelerated cooling at 600 to 700° C., then cooling by 0.4° C./sec or less.

Abstract: The present invention relates to a high-tensile-strength low alloy carbon steel (in the form of a steel sheet, a steel pipe, a section steel or a wire rod), for a building structure, said high-tensile-strength steel being excellent in high temperature strength during a relatively short span of about one hour in the temperature from 600° C. to 800° C. and being used in the field of building construction, civil engineering, an offshore structure, shipbuilding, a reservoir tank or the like; and, more specifically, is a high-tensile-strength steel excellent in high temperature strength, characterized by containing, in mass, C at not less than 0.005% to less than 0.08%, Si at not more than 0.5%, Mn at 0.1 to 1.6%, P at not more than 0.02%, S at not more than 0.01%, Mo at 0.1 to 1.5%, Nb at 0.03 to 0.3%, Ti at not more than 0.025%, B at 0.0005 to 0.003%, Al at not more than 0.06%, and N at not more than 0.006%, with the balance consisting of Fe and unavoidable impurities and satisfying the expression p??0.0029×T+2.

Abstract: The present invention provides a high-strength steel for welded structures excellent in strength at a high temperature of a temperature range of 600° C. to 800° C. and a method of production of the same, in particular 490 MPa class high-strength steel for welded structures excellent in high temperature strength containing C: 0.005% to less than 0.040%, Si: 0.5% or less, Mn: 0.1 to less than 0.5%, P:0.02% or less, S: 0.01% or less, Mo: 0.3 to 1.5%, Nb: 0.03 to 0.15%, Al: 0.06% or less, and N: 0.006% or less and in accordance with need one or more of Cu, Ni, Cr, V, Ti, Ca, REM, and Mg, having a weld crack susceptible formulation PCM defined as PCM=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B of 0.15% or less, substantially not containing B, and a remainder Fe and unavoidable impurities, the microstructure being mainly composed of a mixed structure of ferrite and bainite, and the fraction of bainite being 20 to 90%.

Abstract: A phase modulated light is propagated through an optical fiber sensing loop, from which a propagated light is obtained. The propagated light is converted to an electric signal, from which a fundamental wave component and even number harmonic wave components of a phase modulating signal for the phase modulated signal are detected. In accordance with the changes of the fundamental and even number harmonic wave components, fault is detected. On the other hand, the electric signal may be integrated to provide an integrated signal. In accordance with the comparison between the integrated signal and a fault reference voltage, the fault may be detected.

Abstract: A photodetector generates an electric signal by receiving a light signal which is obtained by coupling lights having propagated through an optical fiber sensing loop in clock-wise and counter clock-wise directions, and modulated in a phase modulator. The electric signal is detected in a synchronous detection circuit to generate a fundamental wave component of the phase modulation signal, a duplicate harmonic wave component, a quadruple harmonic wave component, and an orthogonal component which is obtained in accordance with a phase shift of the quadruple harmonic wave component by one quarter period.

Abstract: A signal processing circuit of an optical fiber gyro comprises a memory for storing data measured in the signal processing circuit in accordance with angular velocities applied to an optical fiber sensing loop at preparatory stage, and the applied angular velocities. In operation, the memory is accessed in accordance with data obtained in the signal processing circuit at an operation stage, so that an angular velocity is read from the memory without complicated calculation.

Abstract: In an optical fiber gyro for detecting a rotation angular velocity by Sagnac phase difference of light signals propagated through an optical fiber sensing loop, no polarizer is used, and a light source having a difference in attenuation or amplification factor between two orthogonally polarized lights is used. Alternatively, a light source is optically coupled to an optical coupler for supplying two divided light signals to the sensing loop and receiving the two light signals propagated through sensing loop by an optical fiber of a predetermined length which is set to meet a relation in which a distance difference determined by the predetermined length and a phase difference of two orthogonally polarized lights propagated through the optical fiber is greater than an interference distance of the light source.

Abstract: The light emitted from a laser diode is divided into two lights and the divided lights are introduced into a sensing loop such that the lights propagate through the sensing loop clockwise and counterclockwise. These lights are combined by a light receiving device and then a signal processing circuit calculates an angular velocity .OMEGA.'. The temperature near the laser diode is detected to obtain a correction value Kt, a current supplied to the laser diode is detected to obtain a correction value Ki and a corrected angular velocity .OMEGA. is obtained by calculating the product of the angular velocity with the correction values Ki and Kt, i.e., .OMEGA.=.OMEGA.'*Ki*Kt.

Abstract: An interference sensor passes radiation from a source and a polariser to a loop of optical fiber so that radiation beams circulate in opposite directions around the loop and interfere. The loop contains an optical phase modulator which imposes an optical modulator on the radiation beams circulating on the loop. A converter detects the interfering and modulated beams and generates an interference signal which is then processed by an analyser. The interference in the loop is dependent on rotation of the loop and therefore analysis of the interference signal permits that rotation to be measured. In the present invention, the interference signal is (i) sampled at a frequency different from that of the optical modulation, or (ii) electronically modulated in the analyser at a frequency different from that of the optical modulation, or (iii) optically modulated in the loop at a second optical modulation frequency. The analysis in the analyser may be in the frequency domain (i.e.

Abstract: In an optical fiber gyroscope, the sensitivity thereof is optimized with a phase bias afforded by utilizing the phase characteristics of an optical branching/coupling unit. Further, the fluctuation of the intensity of a light source and the error and secular change of the phase characteristics of the optical branching/coupling unit are compensated by an electronic circuit. Moreover, an optical fiber loop is located in a heat insulation casing so as not to be affected by an ambient temperature change, thereby to prevent the drift of the optical fiber gyroscope attributed to an temperature change. Thus, the optical fiber gyroscope of high measurement accuracy is provided.

Abstract: A method of producing non-oriented magnetic steel plate having high magnetic flux density in a low magnetic field and uniform magnetic properties through the thickness direction, comprising selection of a heating temperature and finish rolling temperature to coarsen the size of the austenite grains and prevent refinement of the grain size in the rolling process, and annealing the steel after it has been rolled.

Abstract: A method of producing non-oriented magnetic steel heavy plate that has good magnetic properties in a low magnetic field that comprises hot-rolling high-purity steel, adjusting the crystal grain size and dehydrogenation treatment, whereby the a uniform ferrite grain diameter is imparted to the steel.

Abstract: A polarized wave preserving fiber has a core at its center, cladding, an oval jacket, and a support member in order to improve transmitting property of the polarized single mode by adjusting the refractive index distribution and the ellipticity of the oval jacket.