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Structure normal velocity reconstruction withsparse measurement points

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Chinese Journal of Acoustics 2018年第1期37卷 60-68页

作者： MAO Rongfu zhu haichao Institute of Noise & Vibration Naval University of Engineering Wuhan 430033 National Key Laboratory on Ship Vibration & Noise Wuhan 100084

To achieve normal velocity reconstruction of a vibrating surface with sparse mea- surement points, a reconstruction method is proposed by exploiting of acoustic radiation modes as expansion functions, which are capable of describing the geometric shape of a vibrating surface. Firstly, acoustic radiation modes of the vibrating surface are calculated and the rela- tionship between normal velocity and acoustic radiation modes is built. Then actual measured normal velocity values are expressed by corresponding acoustic radiation modes and the expan- sion coefficients are calculated. Subsequently, all normal velocity values can be reconstructed by the obtained expansion coefficients. Experimental validations have been performed by a double-layer steel cylindrical shell with enclosed ends in an anechoic water tank. Two cases with different wavenumber components distribution were designed by a vibration shaker and a rotor device respectively. Two experimental results both show that actual vibration distribution cannot be revealed exactly by the sparse measurement points, which corresponds to severe loss of vibration related wavenumber components. On the other hand, normal velocity and corresponding wavenumber components can be restored accurately in both two wavenumber components distribution cases according to the proposed method, which demonstrates obvious effectiveness of the proposed method.

关键词： Structure normal velocity reconstruction withsparse measurement points

Theory and calculation for acoustic radiation mode of weak coupled enclosure

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Chinese Journal of Acoustics 2019年第3期38卷 331-339页

作者： MAO Rongfu SU Changwei zhu haichao Institute of Noise&Vibration Naval University of EngineeringWuhan 430033 National Key Laboratory on Ship Vibration&Noise Wuhan 430033

Active structural acoustic control(ASAC)is an efficient method in acoustic radiation control of coupled *** the past research of ASAC,the concept of 'acoustic radiation mode(ARM)of coupled enclosure'was proposed,which was a set of basis functions of structural mode ***,there was an incompatibility with the ARM definition in free space radiation case which was a set of basic functions of normal velocity or pressure on the vibrating ***,there was severe inconvenience for application as structural modes were required while accurate and useful structural modes were difficult to be extracted in *** overcome these problems,by analogy to ARM theory of free space,the acoustic potential energy was expressed in quadratic form of normal velocity on coupling surface and ARM of coupled enclosure was ***,theoretic derivation showed that ARM of coupled enclosure could be replaced simply by corresponding acoustic mode projection of enclosure when the coupling surface was discretized into equal size ***,the ARM theory of coupled enclosure which was consistent with that of free space and convenient for application was ***,numerical calculation was performed and the results proved that the presented theory was very efficient in ARM calculation of coupled enclosure and ASAC.

关键词： ARM Theory and calculation for acoustic radiation mode of weak coupled enclosure

Calculation and analysis for acoustic radiation mode of strong and weak plate-cavity coupling systems

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Chinese Journal of Acoustics 2023年第2期42卷 220-234页

作者： LIAO Jinlong zhu haichao HOU Jiuxiao YUAN Suwei National Key Laboratory on Ship Vibration and Noise Institute of Noise and VibrationNaval University of EngineeringWuhan 430033

A method based on the energy principle is proposed for calculating the acoustic radiation mode of plate-cavity coupling *** relationship between the acoustic pressure mode amplitude vector and the structural mode amplitude vector is constructed according to the kinetics equations based on the energy *** acoustic radiation mode of plate-cavity coupling systems is derived by expressing the acoustic potential energy as a quadratic form of the structural mode amplitude *** proposed method bridged the gap in previous theories concerning plate-cavity coupling systems with impedance walls and strong structuralacoustic *** correctness and effectiveness of the proposed method are verified by numerical *** that basis,the effects of changes in wall surface settings and structuralacoustic coupling conditions on the characteristics of acoustic radiation mode are *** results show that the acoustic radiation mode radiation efficiency curve peaks at the acoustic modal frequency,whose amplitude is reduced by using impedance ***,a lower impedance has more significant amplitude attenuation ***,the amplitude of the acoustic potential energy curve at the peak radiation efficiency frequency decreases;under strong coupling conditions,the acoustic potential energy response in the low-frequency band is mainly excited by the structural mode,resulting in a higher response peak density and lower *** the same bandwidth,the acoustic radiation mode in the low-frequency range has fewer radiation efficiency peaks and higher peak frequencies.

关键词： coupling plate impedance

Transmission loss of a flexible micro-perforated muffler with a flexible back cavity for water-filled pipelines

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Chinese Journal of Acoustics 2021年第1期40卷 31-45页

作者： HOU Jiuxiao zhu haichao YUAN Suwei LIAO Jinlong National Key Laboratory on Ship Vibration&Noise Institute of Noise&VibrationNaval University of EngineeringWuhan 430033

To reduce low-frequency noise of the water-filled pipeline system,a compact flexible micro-perforated muffler with a flexible back cavity(FMPMFBC) is *** flexible pipe wall is made of a rubber-cord composite material.A numerical solution for the transmission loss is ***,the flexible micro-perforated panel(FMPP) is equivalent to a flexible porous material based on Biot-Allard porous-elastic ***,a periodic structural unit of the aramid fabric cloth is established with the two-scale method,and the equivalent stiffness matrix is ***,a multi-layer composite model for the flexible pipe wall is constructed according to the lamination *** with the internal sound field,the transmission loss of the FMPMFBC is *** a water-filled impedance tube,the transmission loss curves of the FMPMFBC prototypes are measured with the two source-location method,and compared with those of a flexible micro-perforated muffler with a rigid back cavity(FMPMRBC)and an expansion *** results are experimentally *** FMPMFBC is a hybrid muffler combining reflection with dissipation,capable of attenuating broadband lowfrequency *** transmission loss of prototype B2 in the frequency bands of [40 300] Hz and [40 1200] Hz is 36 dB and 30 dB,respectively,while the transmission loss of the same-sized expansion muffler in the corresponding frequency bands is 7 dB and 11 dB,respectively.

关键词： composite cavity perforated

Sound absorption characteristics of underwater flexible micro-perforated sound absorption structures

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Chinese Journal of Acoustics 2020年第4期39卷 512-525页

作者： HOU Jiuxiao zhu haichao LIAO Jinlong YUAN Suwei National Key Laborutory on Ship Vibration&Noise Institute of Noise&VibrationNaval University of EngineeringWuhan 430033

A mathematical model for the micro-perforated panel in water medium is established using mode superposition method,and an equivalent circuit model is acquired based on electro-acoustic analogy *** of the flexible micro-perforated panel(FMPP) and the flexible back panel(FBP) on normal incidence sound absorption coefficient are *** micro-perforated panel in air medium,the underwater micro-perforated panel cannot achieve any satisfactory sound absorption effect due to insufficient structural *** this end,a strengthened micro-perforated sound absorption structure is *** results are verified in a water-filled impedance *** the range from 20 Hz to 2,000 Hz the average absorption coefficient of the strengthened flexible micro-perforated panel are improved *** absorption coefficient curve gradually approaches rigid micro-perforated panel as the bending stiffness *** flexible back panel can reduce the resonance frequency of the absorption curve and improve the low-frequency sound absorption performance.

关键词： absorption sound underwater

Design,synthesis and biological evaluation of pyridyl substituted benzoxazepinones as potent and selective inhibitors of aldosterone synthase

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Chinese Chemical Letters 2021年第7期32卷 2327-2332页

作者： haichao zhu Meihua Liu Haiyan Li Ting Guan Qi Zhang Yang Chen Yingxiang Liu Rolf RHartmann Lina Yin Qingzhong Hu School of Pharmaceutical Sciences Guangzhou University of Chinese MedicineGuangzhou 51006China Pharmaceutical and Medicinal Chemistry Saarland UniversityCampus C2.3D-66123SaarbruckenGermany

Exorbitant aldosterone is closely associated with various severe diseases,including congestive heart failure and chronic kidney *** aldosterone synthase is the pivotal enzyme in aldosterone biosynthesis,its inhibition constitutes a promising treatment for these *** a structure-based approach,a series of pyridyl substituted 3,4-dihydrobenzo[f][1,4]oxazepin-5(2 H)-ones were designed as inhibitors of aldosterone *** compounds(5 j,5 l,5 m 5 w,5 x and 5 y)distinguished themselves with potent inhibition(IC50<100 nmol/L)and high selectivity over homogenous 11β-*** the most promising compound,5 x exhibited an IC_(50) of 12 nmol/L and an excellent selectivity factor(SF)of157,which are both superior to those of the re ference fadrazole(IC_(50)=21 nmol/L,SF=7).Importantly,5 x showed no inhibition against steroidogenic CYP17,CYP19 and a panel of hepatic CYP enzymes indicating an outstanding sa fety *** it manifested satis factory pharmacokinetic pro perties in rats,compound5 x was considered as a drug candidate for further development.

关键词： Aldosterone synthase Selective inhibitors Benzoxazepinones Heart failure Renal diseases

Near-field acoustic holography analysis of modulated sound source

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Chinese Journal of Acoustics 2011年第4期30卷 398-408页

作者： MAO Rongfu zhu haichao DU Xianghua zhu Haipeng Institute of Noise and Vibration Naval University of Engineering Wuhan 430033

When conventional near-field acoustic holography （NAH） technique is appliedto sound field induced by modulated signal, the modulating frequency can not be revealed by the reconstructed results. To solve the problem, a NAH analysis methodology for modulated sound source was proposed. Firstly, Hilbert transform was introduced to demodulate the signal, and then modulating component was reconstructed by NAH technique. Both numerical simulation and experiment results demonstrate that accurate reconstruction analysis can be obtained by the proposed method.

关键词：调制信号全息分析近场声源声全息技术希尔伯特变换调制频率数值模拟

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稀疏测点条件下的结构法向速度重建

声学学报 2017年第4期42卷 451-456页

作者：毛荣富朱海潮海军工程大学振动与噪声研究所武汉430033 船舶振动噪声重点实验室武汉430033

为了实现稀疏测点条件下结构表面法向速度的准确重建,利用声辐射模态包含结构表面几何形状信息的性质,以声辐射模态作为基函数提出了一种稀疏测点条件下的结构法向振速重建方法。首先对结构表面的声辐射模态进行计算,并建立结构表面法... 详细信息

为了实现稀疏测点条件下结构表面法向速度的准确重建,利用声辐射模态包含结构表面几何形状信息的性质,以声辐射模态作为基函数提出了一种稀疏测点条件下的结构法向振速重建方法。首先对结构表面的声辐射模态进行计算,并建立结构表面法向振动速度与声辐射模态之间的关系;在此基础上,由实际布置情况形成测点位置处的振速与其声辐射模态值的关系,并通过最小二乘法求得展开系数;最后由展开系数重建出结构表面的全部法向振速。利用两端封闭的双层钢质圆柱壳体在消声水池中进行了试验验证,分别开启激振器和转子台进行激励,两个试验的结果均表明,当测点数目较少时,所测的结果不能准确地表示结构的实际振动情况,在波数域内就表现为与振动相关的波数成份的丢失;利用所提出的方法,可以较为准确地重建和恢复结构的表面法向速度及其波数成份,由此验证了所提出方法的有效性。

关键词：声辐射模态结构法振速波数域展开系数圆柱壳体包含结构激振器几何形状最小二乘法

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弱耦合封闭声腔的声辐射模态理论与计算

声学学报 2019年第3期44卷 297-302页

作者：毛荣富苏常伟朱海潮海军工程大学振动与噪声研究所武汉430033 船舶振动噪声重点实验室武汉430033

有源结构声控制是耦合封闭声腔的声辐射控制的有效方法。在此前的研究中有学者提出了"耦合封闭声腔的声辐射模态"概念,但其在概念和应用上均存在不便之处:其定义实质上是结构模态幅值的一组基函数,这与自由空间内声辐射模态是结构表面... 详细信息

有源结构声控制是耦合封闭声腔的声辐射控制的有效方法。在此前的研究中有学者提出了"耦合封闭声腔的声辐射模态"概念,但其在概念和应用上均存在不便之处:其定义实质上是结构模态幅值的一组基函数,这与自由空间内声辐射模态是结构表面法向振速或声压的一组基函数的物理意义并不一致;另一方面,在计算和利用其进行控制时仍然需要用到结构模态,而在实际中辐射结构有用的结构模态信息难以准确、方便地得到。为了解决这些问题,类比自由空间声辐射模态理论,将声势能直接表示为结构表面法向振速的二次型形式,提出了新的结构向耦合封闭声腔的声辐射模态计算方法,并从理论上证明了当耦合面均匀离散时,在一定的条件下,可以简单地利用声腔模态投影向量代替耦合封闭声腔的声辐射模态,从而有效地节约计算资源。通过理论研究,形成了与自由空间内相统一、便于应用的耦合封闭声腔声辐射模态理论,数值计算案例表明,所提出的理论方法可以极大方便耦合封闭声腔的声辐射计算及其有源结构声控制。

关键词：声辐射模态模态理论弱耦合声腔封闭有源结构声控制结构模态自由空间