In order to suppress strong self-interference signals in received signals, a selfinterference suppression method based on transfer function fitting and multistage delay estimation is proposed. Firstly, the transfer fu...In order to suppress strong self-interference signals in received signals, a selfinterference suppression method based on transfer function fitting and multistage delay estimation is proposed. Firstly, the transfer function of transmitting leakage is estimated by frequency domain deconvolution to construct the basic cancellation signal. Then, the multistage delay estimation based on the cross correlation method and the cross spectrum method is used to accurately compensate the cancelling signals to obtain a good selfinterference suppression effect. The processing results of the actual sea trial data indicate that the suppression ratio of the proposed method can reach 36 d B, and the signal-tointerference ratio of the detectable echo can be reduced from-30 d B to-55 d B when the unmanned undersea vehicle(UUV) integrated system is used to transmit multi-frame linear frequency modulated(LFM) signals in the working sector of the side array for active detection of the target ship. The same suppression effect is found for the subsequent selfinterference signals. The above results indicate that the method can suppress the strong self-interference signal, and presents stability, so that the echo signal submerged in the strong self-interference signal can be detected.展开更多
为研究超高性能纤维增强混凝土(ultra high performance fiber-reinforced concrete,UHPFRC)板的受弯性能,进行了10块UHPFRC板的弯曲试验,研究了板的破坏形态、破坏过程、开裂弯矩、极限弯矩以及混凝土和钢筋的应变。在试验结果基础上,...为研究超高性能纤维增强混凝土(ultra high performance fiber-reinforced concrete,UHPFRC)板的受弯性能,进行了10块UHPFRC板的弯曲试验,研究了板的破坏形态、破坏过程、开裂弯矩、极限弯矩以及混凝土和钢筋的应变。在试验结果基础上,建立了考虑受拉区混凝土抗拉强度和应变硬化效应的UHPFRC板受弯承载力计算式。研究结果表明:UHPFRC板的弯曲破坏形态表现为一条主裂缝并伴有多条微裂缝出现,其破坏过程可分为线性变形、微裂缝发展、主裂缝发展和承载力下降四个阶段;UHPFRC板首次出现裂缝时的弯矩为极限弯矩的50%~55%;在设计板时应以变形作为控制指标,且可以少配或不配钢筋以发挥UHPFRC的材料优势;UHPFRC板在受力过程中表现出显著的应变硬化特性。给出了UHPFRC板的弯曲承载力计算式,可以反映受拉区UHPFRC的应变硬化特性。展开更多
基金supported by the Stable Supporting Fund of Acoustic Science and Technology Key Laboratory (JCKYS2021604SSJS011)。
文摘In order to suppress strong self-interference signals in received signals, a selfinterference suppression method based on transfer function fitting and multistage delay estimation is proposed. Firstly, the transfer function of transmitting leakage is estimated by frequency domain deconvolution to construct the basic cancellation signal. Then, the multistage delay estimation based on the cross correlation method and the cross spectrum method is used to accurately compensate the cancelling signals to obtain a good selfinterference suppression effect. The processing results of the actual sea trial data indicate that the suppression ratio of the proposed method can reach 36 d B, and the signal-tointerference ratio of the detectable echo can be reduced from-30 d B to-55 d B when the unmanned undersea vehicle(UUV) integrated system is used to transmit multi-frame linear frequency modulated(LFM) signals in the working sector of the side array for active detection of the target ship. The same suppression effect is found for the subsequent selfinterference signals. The above results indicate that the method can suppress the strong self-interference signal, and presents stability, so that the echo signal submerged in the strong self-interference signal can be detected.
文摘为研究超高性能纤维增强混凝土(ultra high performance fiber-reinforced concrete,UHPFRC)板的受弯性能,进行了10块UHPFRC板的弯曲试验,研究了板的破坏形态、破坏过程、开裂弯矩、极限弯矩以及混凝土和钢筋的应变。在试验结果基础上,建立了考虑受拉区混凝土抗拉强度和应变硬化效应的UHPFRC板受弯承载力计算式。研究结果表明:UHPFRC板的弯曲破坏形态表现为一条主裂缝并伴有多条微裂缝出现,其破坏过程可分为线性变形、微裂缝发展、主裂缝发展和承载力下降四个阶段;UHPFRC板首次出现裂缝时的弯矩为极限弯矩的50%~55%;在设计板时应以变形作为控制指标,且可以少配或不配钢筋以发挥UHPFRC的材料优势;UHPFRC板在受力过程中表现出显著的应变硬化特性。给出了UHPFRC板的弯曲承载力计算式,可以反映受拉区UHPFRC的应变硬化特性。
