AN EXPERIMENTAL INVESTIGATION OF TURNING-POINT CONVERGENCE-ZONES IN A DEEP SOUND CHANNEL IN THE SOUTH CHINA SEA

in October 1983,an experiment was carried out to investigate the characteristics of turning-point convergence-zones and of underwater sound propagation in a deep sound channel in the SouthChina Sea by using explosive sound sources.In this paper,we present the experimental results forthe source depths of 200 m and 500 m.By using the theory on the turning-point convergence-zoneand parabolic approximation,the measured data are analysed.For low-frequencies the measuredpositions and convergence-gains of zones coincide with calculated results quite well.     

ANALYSIS OF INDIVIDUAL MODES IN SHALLOW WATER

The propagaion experiment of explosive sound in the isothermal layer below the thermocline wasmade,and the records of individual modes for the frequencies of 0.32 to 1.0 kHz were obtained.Byanalyzing the travel time of filtered signal,it was determined that the recorded waveforms are the firstmodes.On the basis of the propagation properties of the first modes,the bottom-reflection coeffi-cients at small grazing angles for the frequencies of 0.32 to 1.0 kHz were obtained.     

镧的内耗和磁化率

用自动真空倒扭摆测量了纯镧在80～700K的内耗和相对切变模量,观测到六个内耗峰。升温过程的H_1峰和降温过程的C_2峰是由镧的FCC-dHCP结构相变引起的,H_2和C_1 峰则可能与这种相变还存在着预转变有关。用内耗方法确定了相变点γ_s、γ_(?)、β_s、β(?)分别为540、650、487和425K。H_3、H_4、H_5、H_6四个内耗峰用2.21Hz的频率测得的峰温分别为366、272、207.2、和119K,其中H_5峰具有弛豫型内耗特征。还测量了纯镧在77～700K范围的磁化率,观测到1/X T线段在FCC-dHCP相变温度出现斜率转折。     

轴向磁场强度对真空电弧离子镀TiN薄膜的影响

采用电弧离子镀方法在不锈钢基体上沉积了TiN薄膜,考察了弧靶与基体之间等离子通道上的轴向磁场强度(0-300高斯)对薄膜表面形貌、组织结构、硬度及弹性模量的影响。结果表明,随着轴向磁场的不断增强,等离子体密度及能量密度不断增大,阴极靶斑点处被熔化的靶材区域增大,阴极斑点附近局部蒸气压升高,薄膜表面较大尺寸的大颗粒数、凹坑数量会因此增多,薄膜粗糙度会因此增大;生长取向由(111)面择优转为(220)面择优并最终趋向无择优取向;薄膜表面硬度及弹性模量均呈现先增大后减小的趋势。更多还原     

SPATIAL COHERENCE AND TEMPORAL STABILITY OF THE LONG-RANGE SOUND FIELD IN SHALLOW WATER

The spatial coherence and temporal stability of long-range sound field in shallow water by usingexplosive sources are presented.A experiment was conducted in shallow water with depth of 38 m,the source and receiver depths were 7 m and 6 m,respectively,the longitudinal space correlationabove the thermocline was measured.Another was conducted in shallow water with depth of 60 m,the sources were at 25 and 30 m,and the receiver was at 25 m,the transverse,longitudinal and timecorrelations below the thermocline were measured.The experimental data show that strong spatialcoherence and temporal stability are present in the long-range sound field.     

南海深海声道中反转点会聚区的实验研究

本文介绍了1983年10月在南海深海声道中进行的一次综合性爆炸声传播实验的结果,目的在于研究水下声道中反转点会聚区的特性。用反转点会聚区的渐近理论以及P-E法对声场进行了计算,实验得到的会聚区位置及会聚增益与计算结果很好符合。     

浅海中单个简正波的分析

在跃变层之下的等温层中进行了爆炸声传播实验,获得了频率0.32—1.0kH2的单个简正波的记录。通过对简正波脉冲传播时间的分析,确定所记录的波形为第一号简正波。根据第一号简正波的传播特性,分析得到了频率0.32—1.0千赫的小掠射角海底反射系数。     

浅海远程声场的空间相关性与时间稳定性

本文介绍浅海远程声场空间相关的一些实验结果。实验研究了不同距离、频率与带宽的空间相关,测量数据具有明显的距离与频率依赖关系。实验结果表明,在55至130公里的传播距离上跃变层之下的低频声场有较强的空间相关性与时间稳定性。