宽带声矢量场的表征(英文)

Compared to a scalar pressure sensor, a vector sensor can provide a higher signal-to-noise ratio (SNR) signal and more detailed information on the sound field. Study on vector sensors and their applications have become a hot topic. Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology. This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship, and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform. From theory analysis and numerical simulation, the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but, being quantitatively different, provides additional information on the waveguide, especially through the vertical component. For the range-frequency representation, physical quantities that can better exhibit the interference characteristics of the waveguide are the products of pressure and particle velocity and of the pressure and pressure gradient. An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly. The representation of the vector impulse response was discussed according to two different measurement systems, also known as particle velocity and pressure gradient. The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.     

浅谈我国企业的内部会计控制

分析了我国企业内部会计控制失效的表现和成因，并提出相应的控制措施。     

斯佩里·维克斯液压技术的新发展

斯佩里·维克斯许多年来就一直被大家看作是国际上液压技术的一支重要力量。它在世界的工业、汽车业和航天工业所需的液压元件和液压系统的供应市场上是一家大供应户。约在一年半前,当人们得悉斯佩里·维克斯在美国的分公司打算拍卖其全部液压技术及生产经营权时,引起了很多的猜测。后来又放弃了这种打算。正如我们在去年十月刊中所报导的那样,斯佩里公司发表声明强调指出不再出售其美国的分部,美国分部将继续接受充足的财政资助。此后,斯佩里·维克斯对新产品的研制不断投资,其结果反映在目前正在市场     

浅谈我国企业的内部会计控制

分析了我国企业内部会计控制失效的表现和成因,并提出相应的控制措施.     

沈阳地铁行车间隔及运营交路情况分析研究

沈阳地铁一、二号线自运营以来均采用单一大交路模式组织行车,受各项条件限制,现有行车组织模式很难满足未来客流增长的需要。本文从客流情况、折返能力、车辆数量等运营现状进行分析,研究在保证一、二线运力相互匹配情况下如何进一步提升运力,并且深入分析单一大交路模式过渡到大小交路模式后应急情况下的运营调整措施,最终确定沈阳地铁更加合理的行车间隔及运营交路模式。     

设计重量轻的大型螺旋桨

众所周知,大直径低转速螺旋桨在推进效率方面提供了最佳的结果。但是由于螺旋桨是悬挂在艉轴管外,这种大型螺旋桨的巨大重量势必带来某些问题。纽约造船及轮机工程师学会最新发表的论文《重量轻的大直径螺旋桨》中,作者论述了在韦布(Webb)造船学院进行的重量轻的大型螺旋桨的研究结果。该文的某些主要观点讨论如下。