ULTRASONIC ATTENUATION AND VELOCITY IN FRESH PIG SOFT TISSUES IN VITRO

Ultrasonic attenuation and velocity were measured for six fresh pig tissues:blood vessel,brain,heart,liver,spleen and kidney by using the pulse insertion method. Frequency dependence of attenuation has been found to be nearly linear,with the power rangingfrom 0.96 to 1.39 over the 1—13 MHz at 37℃. Velocity dispersion has been observed for all of the six tissues and the average value was 0.11—O.38 m/s.MHz for frequency range from 5 to 13 MHz at 37℃. Temperature effect over the 7—37℃ range for brain was also studied.Velocity at 1 MHz wasfound to be of positive temperature coefficient with average value 1.3m/s·℃and attenuation at 1,3,5MHz decreased with increasing temperature. Velocity for six tissues studied was an approximately linear function of their whole protein content.Every unit protein percentage concentration raises velocity by about 2.9m/s at 5 MHz and 37℃.     

弯曲模式声波在充液井孔中的传播

本文由波动方程讨论了充液井孔中,弯曲模式声波在弹性和非弹性、无限大井壁介质以及有限大井壁介质情况下沿井轴方向的传播。数值计算了它们的相速度频散曲线和井孔的频率响应特性,计算了衰减正弦信号在井孔中激励的波形。利用PZT压电晶片的弯曲振动模式,制作了偶极子测井换能器,在混凝土浇注的人工模拟井中进行了测试,试验结果与理论计算结果作了对比。     

Numerical Simulation of Shear-Horizontal-Wave-Induced Electromagnetic Field in Borehole Surrounded by Porous Formation

Seismoelectric fieM excited by purely torsional loading applied directly to the borehole wall is considered. A brief formulation and some computed waveforms show the advantage of using shear-horizontal （SH） transverseelectric （TE） seismoelectric waves logging to measure shear velocity in a fluid-saturated porous formation. By assuming that the acoustic field is not influenced by its induced electromagnetic field due to seismoeleetric effect, the coupling governing equations for electromagnetic field are reduced to Maxwell equations with a propagation current source. It is shown that this simplification is valid and the borehole seismoelectric conversion efficient is mainly dependent on the electrokinetic coupling coefficient. The receivers to detect the conversion electromagnetic field and to obtain shear velocity can be set in the borehole fluid in the SH-TE seismoelectric wave log.     

生物媒质非线性效应的超声研究

本文利用比较法测定了若干种生物样品水溶液的非线性声学参数B/A值及其与溶液浓度的依赖关系,葡萄糖、蔗糖、乙二醇水溶液的B/A值均呈现随浓度线性增加的依赖关系,新鲜猪全血的B/A值在26℃时为5.8,文中还计算了乙二醇水溶液的内压强P_*与浓度的关系。     

猪的新鲜离体软组织的超声衰减和速度

本文使用脉冲插入取代法测量了猪的6种新鲜软组织(血管、脑、肾、心、脾及肝)的超声衰减和传播速度。在37℃下,6种软组织的超声衰减系数a_s与频率a_s-f~n之间均满足幂函数关系。在所研究的l—13MHz频段内,n值在0.96—1.39之间。六种软组织的超声速度均表现出微量但颇为明显的频散现象,在5—13MHz频段内平均频散量为0.11—0.38m/s.在7一37℃温度范围内对脑组织超声衰减和传播速度的研究表明:声速(1MHz)随温度单调上升,变化趋势与水中声速类似。声衰减(1、3、5MHz)则随温度上升而下降,但对较低频率,下降的速度变缓。6种软组织的声速值(5MHz,37℃)近似地与它们各自的总蛋白含量成正比,蛋白含量每增加1％约使声速升高2.9m/s。     

全波列声波测井数据处理方法通过部级评定

全波列数字声波测井技术是八十年代发展起来的一种测井新技术、它利用数字技术完整地记录了在井孔条件下激励的滑行纵波、滑行横渡、伪瑞利波和斯通利波等模式的声波.不仅可获取纵波参数,而且可提取井壁岩层的横波声速等参数.进而可计算出岩层的各种弹性参数,为石油、煤炭、水文地质勘探提供了一系列重要的参数. 为了使全波接收信号中的纵横波信号能在时域上较好地分离,须采用长源距测井声系,例如,斯伦贝谢     

ULTRASONIC INVESTIGATION OF NONLINEAR EFFECT IN BIOLOGICAL MEDIUM

The nonlinear acoustic parameter B/A and its dependence on solute concentration have beendetermined for several aqueous solutions of biological samples by using comparative method.TheB/A values for aqueous solutions of dextrose,sucrose,and ethylene glycol were found to increaselinearly with solution concentration.The B/A value for fresh whole porcine blood has been obtained tobe 5.8 at temperature 26℃.Dependence of internal pressure P_* on concentration also has beendetermined for ethylene glycol solution.     

BYI型大功率岩土声波仪

南京大学声学研究所最近研制成功一种新型的岩土声波仪.来自同济大学、工程兵工程学院、河海大学等单位的专家参加了四月初在南京举行的省级技术鉴定会,鉴定委员会认为:该仪器主要性能指标达到了国内先进水平,就发射功率和探测距离而言,达到国外产品的先进水平. 该仪器主要用于岩体、土体、混凝土工程中的现场声波无损检测.由于采用调制脉冲作为发射声源,提高了电声有效转换效率、增加了声功率输出,使检测声波在岩土体中的穿透距离和探测范围大为提高.该仪     

生物媒质中非线性声学参量B/A的研究

本文用插入取代法测量和研究了猪全血、牛全血、牛奶和各种分子量的聚乙二醇水溶液等多种液态生物样品中的非线性声学参量B/A值。聚乙二醇水溶液的B/A值随浓度线性增加,并呈现与分子量无明显依赖关系的特性。 关键词：     

南大声学所举办岩体声波检测学习班

1984年7月20日,南京大学声学研究所与扬州市换能器厂,在扬州市举办了为期20天的“声学基础理论和岩体声波检测”学习班。来自全国20个省市的60多名学员参加了学习,他们主要来自石油、煤炭、水利水电、高校等系统。南京大学信息物理系系主任吴文虬副教授参加了开幕式并作了题为“近代声学的发展概况”的学术报告。学习班重点讲授了声学基础理论,并介绍了声波检测技术在石油、煤炭、水电、混凝土等地质工程中的应用,扬州市换能器厂介绍和演示了该厂的各种岩用换能器。