Abstract: An underwater acoustic communication system includes a transmission device including N transmitters, and a reception device. The reception device includes M (M is an integer of two or more) receivers configured to receive M reception signal sequences corresponding to N transmission signal sequences transmitted from the N transmitters through sound waves, a beam former configured to suppress multipath waves other than direct waves of the M received reception signal sequences and to generate L (L is an integer of two or more) signal sequences from the M reception signal sequences, and a signal estimation unit configured to estimate the N transmission signal sequences based on the L generated signal sequences.

Abstract: An aspect of the present invention is a Doppler compensation system including: a sound wave receiving element that receives a sound wave transmitted by a transmitter; a ground-speed-related quantity acquisition unit that acquires a ground-speed-related quantity that is a physical quantity related to a vector representing a ground speed of a receiver including the sound wave receiving element based on an acceleration of the receiver; an extraction unit that extracts a sound wave including an estimation target sound wave that is a sound wave to be estimated from among sound waves received by the receiver; an arrival direction estimation unit that estimates an arrival direction of the estimation target sound wave based on the estimation target sound wave; a reception-direction-speed-related quantity estimation unit that estimates a quantity related to a speed in a reception direction that is a direction in which the estimation target sound wave viewed from the receiver arrives based on the ground-speed-related q

Abstract: A plurality of transmit antennas of a radio transmission device and a plurality of receive antennas of a radio reception device are located under the sea that is a line-of-sight environment, wherein the radio transmission device selects a frequency channel to be used based on an index value per frequency channel indicating orthogonality between the transmit and receive antennas defined based on a distance between the transmit and receive antennas and an angle indicating a direction of arrival of a radio signal, an interval between the plurality of transmit antennas, an interval between the plurality of receive antennas, and a modulation scheme, the distance between the transmit and receive antennas and the angle indicating the direction of arrival of the radio signal estimated by the radio reception device, and a desired bit error rate to be predetermined, selects the modulation scheme for providing a maximum transmission capacity per the selected frequency channel, separates transmission data into a pluralit

Abstract: A communication device includes a channel estimation unit configured to estimate an impulse response based on signals of sound waves received by each of a plurality of hydrophones, a long delay removal unit configured to remove a long-delay impulse response from the impulse response to generate a post-removal impulse response, a weighting factor calculation unit configured to calculate a weighting factor based on the post-removal impulse response, and a synthesizing unit configured to synthesize the signals received by each of the plurality of hydrophones based on the weighting factor.

Abstract: A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer, the surfactant being represented by the general formula (1): CR1R2R4—CR3R5—X-A, wherein R1 to R5 are each H or a monovalent substituent, with the proviso that at least one of R1 and R3 represents a group represented by the general formula: —Y—R6 and at least one of R2 and R3 represents a group represented by the general formula: —X-A or a group represented by the general formula: —Y—R6; and A is the same or different at each occurrence and is —COOM, —SO3M, or —OSO3M. Also disclosed is a surfactant for polymerization represented by the general formula (1), a method for producing a fluoropolymer using the surfactant, a composition including a fluoropolymer and the surfactant and a molded body including the composition.

Abstract: A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer, the surfactant being represented by the general formula (1): CR1R2R4—CR3R5—X-A, wherein R1 to R5 are each H or a monovalent substituent, with the proviso that at least one of R1 and R3 represents a group represented by the general formula: —Y—R6 and at least one of R2 and R5 represents a group represented by the general formula: —X-A or a group represented by the general formula: —Y—R6; and A is the same or different at each occurrence and is —COOM, —SO3M, or —OSO3M. Also disclosed is a surfactant for polymerization represented by the general formula (1), a method for producing a fluoropolymer using the surfactant and a composition including a fluoropolymer and the surfactant.

Abstract: A composition including a fluoropolymer and substantially free from a compound represented by the following formula (3): (H—(CF2)8—SO3)qM2, wherein M2 is H, a metal atom, NR54, imidazolium optionally containing a substituent, pyridinium optionally containing a substituent, or phosphonium optionally containing a substituent; R5s are each H or an organic group and are the same as or different from each other; and q is 1 or 2.

Abstract: A method for producing a fluoropolymer of the invention which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R1a—CO—R2a—CO—R3a-Aa and a surfactant represented by R1b—CO—(CR2b2)n—(OR3b)p—(CR4b2)q-L-Ab.

Abstract: Provided is a method for producing a fluoropolymer, the method including a polymerizing step of polymerizing tetrafluoroethylene in an aqueous medium in the presence of an initiator, a chain transfer agent, and a surfactant to provide a fluoropolymer containing more than 80 mol % of a polymerized unit based on tetrafluoroethylene, the chain transfer agent including at least one selected from the group consisting of a dithioester compound, a dithiocarbamate compound, a trithiocarbonate compound, and a xanthate compound. Also provided is a fluoropolymer represented by the formula Af-CRP defined in the description.

Abstract: Provided is a radio communication system including a radio transmission apparatus including a plurality of transmission antennas and a radio reception apparatus including a plurality of reception antennas.

Abstract: A plurality of transmit antennas of a radio transmission device and a plurality of receive antennas of a radio reception device are located under the sea that is a line-of-sight environment, wherein the radio transmission device selects a frequency channel to be used based on an index value per frequency channel indicating orthogonality between the transmit and receive antennas defined based on a distance between the transmit and receive antennas and an angle indicating a direction of arrival of a radio signal, an interval between the plurality of transmit antennas, an interval between the plurality of receive antennas, and a modulation scheme, the distance between the transmit and receive antennas and the angle indicating the direction of arrival of the radio signal estimated by the radio reception device, and a desired bit error rate to be predetermined, selects the modulation scheme for providing a maximum transmission capacity per the selected frequency channel, separates transmission data into a pluralit

Abstract: A sulfonic acid or carboxylic acid containing a carbonyl group, or a salt thereof represented by the following formula: R1—C(?O)—(CR22)n—(OR3)p—(CR42)q-L-A wherein R1, R2, R3, R4, n, p, q, A and L are as defined herein.

Abstract: A communication device includes a channel estimation unit configured to estimate an impulse response based on signals of sound waves received by each of a plurality of hydrophones, a long delay removal unit configured to remove a long-delay impulse response from the impulse response to generate a post-removal impulse response, a weighting factor calculation unit configured to calculate a weighting factor based on the post-removal impulse response, and a synthesizing unit configured to synthesize the signals received by each of the plurality of hydrophones based on the weighting factor.

Abstract: An organic fine particle capable of adhering to a substrate under a state having a particle shape, wherein the organic fine particle, when adhered to a substrate, exhibits water-repellency on the substrate, and the organic fine particle is formed of a fluorine-free polymer. Also disclosed is an organic fine particle containing: (1) a hydrophobic monomer which has one ethylenically unsaturated double bond and at least one hydrocarbon group having 3-40 carbon atoms; or (2) a polymer which has a repeating unit formed from a (meth)acrylic monomer having a polydimethylsiloxane group. Also disclosed is a method for producing the organic fine particle and a water-repellent composition which is an aqueous dispersion of the organic fine particle. Also disclosed is a textile product and method for treating the same which includes applying a treatment liquid containing the water-repellent composition to the textile product.

Abstract: A surfactant for polymerization including at least one selected from a surfactant represented by R1a—CO—R2a—CO—R3a—OSO3Xa and a surfactant represented by R1b—CO—(CR2b2)n—(OR3b)p—(CR4b2)q-L-OSO3Xb, wherein R1a, R2a, R3a, Xa, R1b, R2b, R3b, R4b, L and Xb are as defined herein. Also disclosed is a composition containing a fluoropolymer and the at least one surfactant, a composition containing a fluoropolymer and a compound represented by (H—(CF2)8—SO3)qM2, where M2 is as defined herein, and a molded article made from the composition containing a fluoropolymer and the compound represented by (H—(CF2)8—SO3)qM2.

Abstract: A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R1a—CO—R2a—CO—R3a—OSO3Xa and a surfactant represented by R1b—CO—(CR2b2)n—(OR3b)p—(CR4b2)q-L-OSO3Xb.

Abstract: A method for producing a fluoropolymer by solution polymerization or dispersion polymerization, the method including: in the presence of an initiator, a chain transfer agent, and a solvent, (i) homopolymerizing tetrafluoroethylene; or (ii) randomly copolymerizing tetrafluoroethylene and at least one of a monomer represented by the following formula (1) or a monomer represented by the following formula (2). The chain transfer agent includes at least one selected from dithioester compounds, dithiocarbamate compounds, trithiocarbonate compounds and xanthate compounds. The fluoropolymer contains 50 to 100 mol % of a polymerized unit based on the tetrafluoroethylene. The formula (1): CF2?CR1R2 wherein R1 and R2 are as defined herein, the formula (2): CH2?CR3R4 wherein R3 and R4 are as defined herein.

Abstract: An underwater acoustic communication system includes a transmission device including N transmitters, and a reception device. The reception device includes M (M is an integer of two or more) receivers configured to receive M reception signal sequences corresponding to N transmission signal sequences transmitted from the N transmitters through sound waves, a beam former configured to suppress multipath waves other than direct waves of the M received reception signal sequences and to generate L (L is an integer of two or more) signal sequences from the M reception signal sequences, and a signal estimation unit configured to estimate the N transmission signal sequences based on the L generated signal sequences.

Abstract: A polytetrafluoroethylene having a breaking strength of 10.0 N or more and a thermal instability index (TII) of 20 or more. Also disclosed is a stretched body including the polytetrafluoroethylene.

Abstract: A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R1a—CO—R2 a—CO—R3a—OSO3Xa and a surfactant represented by R1b—CO—(CR2b2)n—(OR3b)p—(CR4b2)q-L-OSO3Xb.