Author
Hirokazu Karasawa
Bio: Hirokazu Karasawa is an academic researcher from Toshiba. The author has contributed to research in topics: Ultrasonic sensor & Ultrasonic testing. The author has an hindex of 9, co-authored 23 publications receiving 633 citations.
Papers
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Patent•
25 Apr 2005TL;DR: In this article, a three-dimensional ultrasonic inspection apparatus is described, which includes an ultrasonic sensor as a transducer, in which a plurality of piezoelectric vibrators are disposed in a matrix or an array.
Abstract: A three-dimensional ultrasonic inspection apparatus includes: a sensing device for ultrasonic inspection including an ultrasonic sensor as a transducer, in which a plurality of piezoelectric vibrators are disposed in a matrix or an array; a drive element selecting unit for selecting and driving a piezoelectric vibrator for producing an ultrasonic wave among the ultrasonic transducer; a signal detecting circuit for detecting the electric signal of the reflected echo by receiving the reflected echo from the joined area; a signal processing unit for subjecting the electric signal to signal processing and generating three-dimensional imaging data by causing the electric signals to correspond to mesh elements in a three-dimensional imaging region of the object to be inspected; and a display processing device for displaying the detection results and three-dimensional image data from the signal processing unit, while detecting the size and the position of the molten-solidified portion, and the size and the position of the weld defect of the joined area, from the intensity distribution of the three-dimensional imaging data generated by the signal processing unit.
360 citations
TL;DR: In this paper, an under-sodium ultrasonic visual inspection technique was developed in order to observe in-vessel structures in a Fast Breeder Reactor (FBR) whose reactor vessel is filled with opaque liquid sodium.
Abstract: We have developed an advanced under-sodium ultrasonic visual inspection technique in order to observe in-vessel structures in a Fast Breeder Reactor (FBR) whose reactor vessel is filled with opaque liquid sodium. The final goal of this work is achievement of resolution equivalent to that of an image obtained by optical fiber scope. The under-sodium ultrasonic visualizing system consists of a matrix-arrayed transducer and a signal- processing device. The matrix-arrayed transducer, in which 36x36 piezoelectric elements are arranged with 5 mm interval and sealed by a thin metal diaphragm, can realize a 3-dimensional image with high resolution. Regarding signal processing, the 3-dimensional image synthetic processing and the cross correlation processing for the purpose of improving S/N ratio of ultrasonic echoes are implemented on a high-speed parallel processor. Under-sodium imaging test was carried out, and it was confirmed that a 3-dimensional image of the blind target, which was prepared without informati...
58 citations
Patent•
14 Nov 2002
TL;DR: An ultrasonograph for carrying out examination simply and quickly while achieving high resolution and high speed processing, an ultrasonic transducer, an examining instrument, and ultrasonographing device the subject matter are disclosed as mentioned in this paper.
Abstract: An ultrasonograph for carrying out examination simply and quickly while achieving high resolution and high-speed processing, an ultrasonic transducer, an examining instrument, and ultrasonographing device the subject matter are disclosed Piezoelectric layers constituting an ultrasonic transducer are made of barium titanate BaTiO3 or lead titanate zirconate PZT is used and the thickness of each piezoelectric layer is 01 to 100 microm The ultrasonograph comprises a drive unit for driving one of the piezoelectric layers, a sensing unit for sensing electric signals generated by piezoelectric layers receiving echos from the object subjected to ultrasonic wave transmitted by the driven piezoelectric layer, and a processing unit for visualizing the state of the subjected object by processing the sensed electric signal
45 citations
TL;DR: In this paper, the authors investigated high-cycle fatigue characteristics of quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates [−45/0/45/90]s up to 108 cycles.
Abstract: High-cycle fatigue characteristics of quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates [−45/0/45/90]s up to 108 cycles were investigated To assess the fatigue behavior in the high-cycle region, fatigue tests were conducted at a frequency of 100 Hz, since it is difficult to investigate the fatigue characteristics in high-cycle at 5 Hz Then, the damage behavior of the specimen was observed with a microscope, soft X-ray photography and a 3D ultrasonic inspection system In this study, to evaluate quantitative characteristics of both transverse crack propagation and delamination growth in the high-cycle region, the energy release rate associated with damage growth in the width direction was calculated Transverse crack propagation and delamination growth in the width direction were evaluated based on a modified Paris law approach The results revealed that transverse crack propagation delayed under the test conditions of less than σ max/σ b = 03 of the applied stress level
43 citations
Patent•
13 Jun 2005TL;DR: In this paper, an ultrasonic transducer with a plurality of piezoelectric vibrators and a signal detecting circuit was proposed for improving the accuracy of internal inspection of an object to be inspected.
Abstract: The object of the present invention is to provide a the three-dimensional ultrasonic imaging apparatus for improving accuracy of internal inspection of an object to be inspected and enabling an automatic determination by means of ultrasonic waves. The three-dimensional ultrasonic imaging apparatus according to the present invention includes: an ultrasonic transducer having a plurality of piezoelectric vibrators; a driving element selecting portion for selecting a piezoelectric vibrator to emit an ultrasonic wave among a plurality of the piezoelectric vibrators; a signal detecting circuit for causing ultrasonic waves emitted by the selected piezoelectric vibrator to enter the object to be inspected, receiving echo reflected from the object to be inspected, and thereby detecting an electric signal corresponding to the reflected echo; a signal processing portion for generating three-dimensional imaging data by subjecting the electric signal corresponding to the detected reflected echo to parallel arithmetic processing; and a display processing device for receiving the three-dimensional imaging data from the signal processing portion, correcting image luminance of the three-dimensional imaging data so as to flatten imaging intensity distribution in the plane direction of the surface of the object to be inspected, and then displaying a corrected result.
26 citations
Cited by
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Patent•
25 Apr 2005TL;DR: In this article, a three-dimensional ultrasonic inspection apparatus is described, which includes an ultrasonic sensor as a transducer, in which a plurality of piezoelectric vibrators are disposed in a matrix or an array.
Abstract: A three-dimensional ultrasonic inspection apparatus includes: a sensing device for ultrasonic inspection including an ultrasonic sensor as a transducer, in which a plurality of piezoelectric vibrators are disposed in a matrix or an array; a drive element selecting unit for selecting and driving a piezoelectric vibrator for producing an ultrasonic wave among the ultrasonic transducer; a signal detecting circuit for detecting the electric signal of the reflected echo by receiving the reflected echo from the joined area; a signal processing unit for subjecting the electric signal to signal processing and generating three-dimensional imaging data by causing the electric signals to correspond to mesh elements in a three-dimensional imaging region of the object to be inspected; and a display processing device for displaying the detection results and three-dimensional image data from the signal processing unit, while detecting the size and the position of the molten-solidified portion, and the size and the position of the weld defect of the joined area, from the intensity distribution of the three-dimensional imaging data generated by the signal processing unit.
360 citations
TL;DR: An ultrasound system has a catheter including an elongate flexible catheter body having at least one lumen extending longitudinally therethrough as mentioned in this paper, which provides a method for reverse irrigation and removal of particles.
Abstract: An ultrasound system has a catheter including an elongate flexible catheter body having at least one lumen extending longitudinally therethrough. The catheter further includes an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end coupled to the distal end of the catheter body. The distal end of the catheter body is deflectable. The ultrasound system also includes a sonic connector that connects the ultrasound transmission member to an ultrasound transducer. The ultrasound system also provides a method for reverse irrigation and removal of particles.
286 citations
Patent•
13 Feb 2004
TL;DR: In this paper, an absorber member is disposed on or around the ultrasound transmission wire at a location adjacent the sonic connector of the catheter to absorb heat, vibrations, and/or the like from the ultrasound transducer.
Abstract: Ultrasound catheter devices and methods of the present invention generally provide for ablation and/or disruption of vascular occlusions. An ultrasound transmission member, such as a wire, transmits vibrational energy from an ultrasound transducer to a distal head of the catheter to disrupt vascular occlusions. At least one absorber member is disposed on or around the ultrasound transmission wire at a location adjacent the sonic connector of the catheter. The absorber member absorbs heat, vibrations, and/or the like from the ultrasound transmission wire at or near the area where the transmission wire is coupled with the sonic connector. The absorptive function typically slows the process of wear and tear on the transmission wire, thus extending the useful life of the ultrasound catheter.
236 citations
TL;DR: In this paper, an overview of the development of methods for the prediction of fatigue driven delamination growth over the past 40 years is given, and four categories of methods are identified: stress/strain-based models, fracture mechanics based models, cohesive zone models, and models using the extended finite element method.
225 citations
Patent•
01 Feb 2011
TL;DR: A proximal housing of an ultrasound catheter device may include one or more features for dissipating heat from the ultrasound transmission wire, such as a fluid inlet aperture for passage of fluid, use of heat conductive materials in the proximal house, surface features to increase the housing's surface area, heatconductive members disposed adjacent the transmission member and the like.
Abstract: Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions Generally, an ultrasound catheter device includes an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and a distal head coupled with the transmission member and positioned adjacent the distal end of the catheter body for disrupting occlusions A proximal housing of the catheter device may include one or more features for dissipating heat from the ultrasound transmission wire, such as a fluid inlet aperture for passage of fluid, use of heat conductive materials in the proximal housing, surface features to increase the housing's surface area, heat conductive members disposed adjacent the transmission member and the like Various irrigation fluids may be used, such as cooled, oxygen supersaturated or lubricious fluids
165 citations