Evaluating a 3D Ultrasound Imaging Resolution of Single Transmitter/Receiver with Coding Mask by Extracting Phase Information.

We are currently investigating the ultrasound imaging of a sensor that consists of a randomized encoding mask attached to a single lead zirconate titanate (PZT) oscillator for a puncture microscope application. The proposed model was conducted using a finite element method (FEM) simulator. To increase the number of measurements required by a single element system that affects its resolution, the transducer was rotated at different angles.

Improvement of Performance Degradation in Synthetic Aperture Extension of Enhanced Axial Resolution Ultrasound Imaging Based on Frequency Sweep.

We are studying a method based on the carrier frequency sweep for axial high resolution ultrasonic imaging to provide the range resolution that corresponds to the carrier wavelength. The first proposal for this type of method was based on the focused pulse transmission. Then, to improve the frame rate, the method was extended to a synthetic aperture-type method that transmits divergent pulses.

Adhesion and friction properties of molecularly thin perfluoropolyether liquid films on solid surface.

The adhesion and friction properties of molecularly thin perfluoropolyether (PFPE) lubricant films dip-coated on a diamond-like carbon (DLC) overcoat of magnetic disks were studied using a pin-on-disk-type micro-tribotester that we developed. The load and friction forces were simultaneously measured on a rotating disk surface under an increasing/decreasing load cycle and slow sliding conditions. Experiments were performed using two types of PFPE lubricants: Fomblin Z-tetraol2000S with functional end-groups and Fomblin Z-03 without any end-group.

Transmission of 100-MHz-range ultrasound through a fused quartz fiber.

Purpose: This paper describes an investigation into direct observation of microscopic images of tissue using a thin acoustic wave guide.

Methods: First, the characteristics of the ultrasonic wave propagated in a fused quartz fiber were measured using the reflection method in order to study the insertion loss and the frequency shift of the ultrasonic wave transmitted from the transducer. Next, a receiving transducer was placed close to the end of the fiber, and the characteristics of the ultrasonic waves propagated through the acoustic coupling medium were measured using the penetration method in order to study the insertion loss and the frequency-dependent attenuation of the penetrated waves.

SMEM algorithm is not fully compatible with maximum-likelihood framework.

The expectation-maximization (EM) algorithm with split-and-merge operations (SMEM algorithm) proposed by Ueda, Nakano, Ghahramani, and Hinton (2000) is a nonlocal searching method, applicable to mixture models, for relaxing the local optimum property of the EM algorithm. In this article, we point out that the SMEM algorithm uses the acceptance-rejection evaluation method, which may pick up a distribution with smaller likelihood, and demonstrate that an increase in likelihood can then be guaranteed only by comparing log likelihoods.