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当频率高于10kHz时,海水的声吸收主要是硫酸镁的化学驰豫声吸收和纯水的吸收,多年来,由Schulkin和Marsh所提出的海水声吸收公式得到了广泛的应用,不过,早在1965 相似文献
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本文由短脉宽下混响强度的普遍表达式Ir(t,τ)=Kτt-me-βt出发,导出对应的可用于长脉宽的混响强度精确表达式,并给出了忽略脉宽尺度范围的指数衰减损失后相应的近似表达式。当指数衰减系数β足够小和脉宽大于有效脉宽τm=amt(am随m增大而减小,m是大于2的实数)时,近程混响强度趋向饱和且随时间t的(m-1)次幂衰减。实验结果与理论符合较好。 相似文献
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The dependencies of the relaxation frequency and the maximum absorption per wavelength ofboric acid relaxation on B(OH)_3 and NaHCO_3 concentrations were obtained by the cylindrical resona-tor method.The experimental results may be explained by an apparent one-step process:Theory and experimental results show that the effects of calcium on the relaxation parameters of boricacid relaxation can be interpreted by a coupled-reaction system,which is equivalent to that apparentone-step process,including all the ion association reactions. 相似文献
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海水的低频化学弛豫声吸收 总被引:1,自引:0,他引:1
用圆柱共振器法测量了三种混合水溶液的声吸收与pH值的依赖关系,溶液中每种化学成分的浓度均参照Lyman-Fleming人造海水配方中对应成分的浓度来选取。测量的频率为2.9和6.8kHz。温度为12.4℃。结果表明,在海水的pH值范围内,B(OH)_3弛豫的弛豫频率与pH值没有明显依赖关系。另外由实验结果可以看出在B(OH)_3/CO_2/Ca/Mg/NaCl水溶液中还存在一个由MgHCO~+_3引起的低频弛豫,其弛频约为3.5kHz。文末列出了由本文测得的B(OH)_3,MgCO_3和MgHCO~+_3弛豫的弛豫参数。 相似文献
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The dependencies of sound absorption on pH value of B(OH)_3/CO_2/Ca/NaCl,B(OH)_3/CO_2/Ca/Mg/NaCl and Mg/CO_2/Ca/NaCl systems are measured at 2.9 and 6.8 kHz by the cylindrical resonatormethod.The concentration of each constituent in these systems is the same as that in Lymanand Fleming sea water.Measurements are made at atmospheric pressure and 12.4℃.Results showthat the relaxation frequency of B(OH)_3 is independent of the pH value in the seawater.It seemsclear that there is another low frequency relaxation caused by MgHCO_3~+(f_r~3.5 kHz)in theB(OH)_3/CO_2/Ca/Mg/NaCl system.The relaxation parameters of the B(OH)_3,MgCO_3 and MgHC0_3~+relaxations for various systems are given. 相似文献
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The dependence of sound absorption coefficient in natural sea water on pH at frequencies of 2.91,6.82and 10.76 kHz has been measured by the resonator method.Measure-ments were made at 12.6℃ in the pHrange 6.48—8.51.Comparison of the experimental results with predictions based on various equations isgiven.One of the principal objectives in this paper is to examine the contribution of the MgSO_4 absorption insea water by reducing pH to low enough values where the pH-dependent absorption losses become negligible.It seems clear that in order to predict sound absorption in sea water more accurately at both low and highfrequency ranges with an united equation,the equation should include the MgHCO_3~+ absorption term as wellas the MgCO_3 term. 相似文献
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In this paper,the expressions for the relaxation frequency and the maximum absorption perwavelength of the MgSO_4 relaxation as a function of temperature are presented,based on the datafor sound absorption in natural sea water measured by the reverberation method at 27 different tem-peratures between 4 and 29℃. 相似文献
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