Single-sided Access Research Articles

Technik und Methodik der Uterusmyomembolisation

Uterine leiomyomas are the most common benign tumors of the female urogenital tract. Beside the classic surgical treatment options the minimal-invasive embolization therapy of the leiomyomas increasingly gains importance world-wide. Technique, complications, and results of uterine leiomyoma embolization will be presented. After careful evaluation of indications for embolization the procedure is mostly performed under conscious sedation. A single-sided femoral access route together with cross-over technique generally allows for a flow-directed embolization via both uterine arteries. After embolizing the vessels supplying the tumor, the uterine arteries should be still patent. The success rate of embolization of uterine leiomyomas ranges between 85 and 100%, whereas a reduction in size of the tumors in 42 to 83% and a relief of symptoms in up to 96% can be achieved. The total complication rate is about 10% with mainly "minor complications". Worldwide only three deaths following embolization of uterine leiomyomas were reported. The high technical and clinical success rate together with a low complication rate make the embolization of uterine leiomyomas a minimally-invasive alternative to the classic treatment. As long term results are not available indication to embolization of uterine leiomyomas must be carefully established in consensus with gynecologists.

‘Single-sided’ autofocusing of sound in layered materials

A new technique—‘single-sided’ autofocusing—is proposed and its possible use forinspecting layered materials is surveyed. Based on linear acoustics and therecently developed mathematical theory of focusing, single-sided autofocusinganswers the question, ‘Given single-sided access, how does one focus sound to apoint inside a one-dimensional layered medium at a specified time—given that thevelocity profile is unknown?’

Applications of electromagnetic acoustic transducers in the NDE of non-conducting composite materials

An electromagnetic acoustic transducers (EMAT) can usually generate or detect an ultrasonic wave in an electrically conducting material across a small gap. The transducer is a unique ultrasonic EMAT probe that does not require a couplant or gel. Therefore it can be applied in a noncontact mode with a high degree of reproducibility. Shear waves and Lamb waves can be easily generated with EMATs in single-sided access. However, the application of EMAT has been limited to electrically conducting materials. In this work, EMAT was applied to the inspection of nonconducting composites by adhering a removable aluminum foil tape on the part surface. Ultrasonic waves generated in the aluminum layer by the EMAT readily propagated into the nonconducting composite. The reversed process was used in the reception of ultrasonic waves by EMAT. For composites that contained surface metallizations (e. g., metal foil or mesh) for lightning protection and electromagnetic interference (EMI) purposes, EMAT probes were placed directly on the composite surface. Finally, EMAT-generated, normal-incidence shear waves were used for the inspection of “green” laminates before curing to detect errors in ply orientation and layup sequence.

Characterization of capacitive array for NDE applications

Abstract We have developed a capacitive array sensor which responds to the complex dielectric constant of an interrogated material. The sensor requires only single-sided access and operates in a differential mode for detection of discontinuities in the relative dielectric constant, e r , or in the absolute mode where the interest is in absolute quantities. The device in general is noncontacting but can be fabricated as an embedded sensor. Various proof-of-concept studies have been performed to explore possible applications of the device. In the differential mode, small surface features (notches) were detected in a conductor; in dielectrics, both surface and subsurface features were detected. The probe was sensitive to change in impedance caused by a curing epoxy, viewed through a graphite-epoxy composite panel. A study was performed to assess the use of the probe for noncontact characterization of sintering of ceramics. In this (absolute) mode, the effects of liftoff and dielectric constant must be separa...

Characterization of Capacitive Array for NDE Applications

Abstract We have developed a capacitive array sensor which responds to the complex dielectric constant of an interrogated material. The sensor requires only single-sided access and operates in a differential mode for detection of discontinuities in the relative dielectric constant, ε r , or in the absolute mode where the interest is in absolute quantities. The device in general is noncontacting but can be fabricated as an embedded sensor. Various proof-of-concept studies have been performed to explore possible applications of the device. In the differential mode, small surface features (notches) were detected in a conductor; in dielectrics, both surface and subsurface features were detected. The probe was sensitive to change in impedance caused by a curing epoxy, viewed through a graphite-epoxy composite panel. A study was performed to assess the use of the probe for noncontact characterization of sintering of ceramics. In this (absolute) mode, the effects of liftoff and dielectric constant must be separated. We propose a scheme based on the ability to multiplex the capacitive array probe to accomplish this. Preliminary investigation shows that the effect of parasitic capacitance between the probe and ground points in the environment must be suppressed.