Construction and Performance of an Experimental Phased Array Acoustic Imaging Transducer

1981 ◽  
Vol 3 (4) ◽  
pp. 352-368 ◽  
Author(s):  
J. Fleming Dias
Keyword(s):  
Silicone Rubber ◽  
Common Ground ◽  
Phased Array ◽  
Acoustic Imaging ◽  
Metal Foil ◽  
Acoustic Lens ◽  
Array Transducer ◽  
The Common ◽  
And Performance ◽  
Pulse Echo

A technique for electrically connecting to the PZT elements in a phased array transducer of a cardiac imaging probe is described. The transducer is a stack consisting of a PZT substrate with metallized faces and is bonded to an acoustic absorber across a thin alumina substrate of proper acoustic impedance. The PZT substrate is sawed into an array of elements and a metal foil with an integrally moulded acoustic lens is bonded to the tops of the elements to form the common ground connection. The transducer stack is enclosed in an alumina box and the electrical connection to the PZT elements is made by silk-screened metallic conductors on the sides of the box. The stack transducer module is enclosed in a two part linen bakelite case which is sealed by injecting silicone rubber. A technique that was used to prepare the surface of the acoustic absorber, which resulted in wide bandwidth transducers, is described. Finally, we show the pulse-echo response of the completed transducer imaging a point target in water.

An Experimental Investigation of the Cross-Coupling between Elements of an Acoustic Imaging Array Transducer

1982 ◽  
Vol 4 (1) ◽  
pp. 44-55 ◽  
Author(s):  
J. Fleming Dias
Keyword(s):  
Experimental Investigation ◽  
Surface Waves ◽  
Common Ground ◽  
Cross Coupling ◽  
Acoustic Mode ◽  
Acoustic Imaging ◽  
Range Resolution ◽  
Array Transducer ◽  
Coupling Mode ◽  
The Cross

In a phased array acoustic imaging transducer, the cross coupling between elements of the array can lead to a loss in range resolution, cause an increase in rolloff with angle of the sector scan, and increase the ringdown time. In this paper, we present results of an experimental investigation of an acoustic mode that couples the elements through the propagation of surface waves on the surface of the acoustic absorber. These results indicate that the strength of the mode is enhanced by the coherent reflections from adjacent neighbor elements which act as efficient reflectors of the surface waves. We also demonstrate a technique whereby reflections can be made to interact destructively to reduce the strength of that coupling mode. A further reduction can be obtained by stiffening the structure by bonding to the tops of the elements a thick brass foil and by using it as a common ground connection.

The Poetic Thing (On Poetry and Deconstruction)

2011 ◽  
Vol 33 (2) ◽  
pp. 231-243 ◽  
Author(s):  
John W. P. Phillips
Keyword(s):  
Common Ground ◽  
The Common ◽  
And Performance ◽  
As If

Deconstruction has sometimes been championed as if it was a kind of poetic (as opposed to say analytic) writing. The identification has encouraged some to relegate deconstruction to the shadows or sidelines, the sideshows, of serious philosophy. Both tendencies are foolish. There nonetheless remains the question of the relation between two enigmatic discourses: poetry and deconstruction; some deep complicity is surely implied. Reading in the texts of philosophy and poetry the adventure and performance of the names themselves, philosophy, poetry and deconstruction, it is possible to outline the consistency of a logic, according to which: as poetry must have its thing, so too must deconstruction; and philosophy would be deconstruction's poetic thing. The common ground (of poetry and deconstruction) would be the photograph (in ancient and modern senses) recording the loss of what disappears into its appearance. After deconstruction philosophy can therefore only be accomplished otherwise, not as poetry, but as a poetic thing.

A Model to Predict Phased Array Ultrasonic Testing Signals from a Flat-Bottomed Hole in Two Medium

2006 ◽  
Vol 321-323 ◽  
pp. 501-504 ◽  
Author(s):  
Sung Jin Song ◽  
Joon Soo Park ◽  
Hak Joon Kim ◽  
Un Hak Seong ◽  
Suk Chull Kang ◽  
...  
Keyword(s):  
Phased Array ◽  
Steel Specimen ◽  
Measurement Model ◽  
Beam Model ◽  
Flat Bottom ◽  
Ultrasonic Signals ◽  
Array Transducer ◽  
Ultrasonic Phased Array ◽  
Set Up ◽  
Pulse Echo

In this study, the expanded multi-Gaussian beam model is adopted to develop a model to calculate the ultrasonic beam fields radiated from an ultrasonic phased array transducer. Combining this beam model with three other components including time delays, a far-field scattering model and a system efficiency factor, we develop a complete ultrasonic measurement model for predicting the phased array ultrasonic signals that can be captured from a flat-bottom hole in a steel specimen in a pulse-echo set-up using an array transducer mounted in a solid wedge. This paper describes the complete model developed with its key ingredients.

The Semantics of Evidentials

2017 ◽  
Author(s):  
Sarah E. Murray
Keyword(s):  
Recent Work ◽  
Common Ground ◽  
Formal Semantics ◽  
Empirical Support ◽  
Propositional Content ◽  
Primary Data ◽  
Truth Conditional ◽  
The Common ◽  
Issue Content

This book gives a compositional, truth‐conditional, crosslinguistic semantics for evidentials set in a theory of the semantics for sentential mood. Central to this semantics is a proposal about a distinction between what propositional content is at‐issue, roughly primary or proffered, and what content is not‐at‐issue. Evidentials contribute not‐at‐issue content, more specifically what I will call a not‐at‐issue restriction. In addition, evidentials can affect the level of commitment a sentence makes to the main proposition, contributed by sentential mood. Building on recent work in the formal semantics of evidentials and related phenomena, the proposed semantics does not appeal to separate dimensions of illocutionary meaning. Instead, I argue that all sentences make three contributions: at‐issue content, not‐at‐issue content, and an illocutionary relation. At‐issue content is presented, made available for subsequent anaphora, but is not directly added to the common ground. Not‐at‐issue content directly updates the common ground. The illocutionary relation uses the at‐issue content to impose structure on the common ground, which, depending on the clause type (e.g., declarative, interrogative), can trigger further updates. Empirical support for this proposal comes from Cheyenne (Algonquian, primary data from the author’s fieldwork), English, and a wide variety of languages that have been discussed in the literature on evidentials.

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