We have devised a method, based on a parametric array concept, to create a low-frequency (300-500 kHz) collimated ultrasound beam in fluids highly attenuating to sound. This collimated beam serves as the basis for designing an ultrasound visualization system that can be used in the oil exploration industry for down-hole imaging in drilling fluids. We present the results of two different approac...

Introduction: This study aimed to evaluate the efficacy of a synthesized bolus in the reduction of damage to body tissues and the protection of the organ at risk (OAR) in radiotherapy application. Several properties of the synthesized bolus, including density, transmission factor, and effective mass attenuation coefficient, were investigated. Material and ...

Background: In radiation therapy, water is the phantom material of choice, both for reference and for relative dosimetry measurements. Solid phantoms, however, are more useful for routine measurements because they tend to be more robust and easier to set up than water phantoms. Materials and Methods: FLUKA input data cards have been arranged in sequential order. A simple cylindrical geometry wi...

OBJECTIVE Estimates of ultrasonic attenuation (the loss of energy as an ultrasonic wave propagates through tissue) have been used to evaluate the structure and function of tissues in health and disease. The purpose of this research was to develop a method to estimate ultrasonic cervical attenuation during human pregnancy using a clinical ultrasound system. METHODS Forty women underwent a cerv...

In this study, the dispersion of an infinite shear beam with a lumped mass connected at periodic distances and resting on elastic foundation was examined. The effect periodicity in finite region masses wave propagation investigated through one-dimensional model. relationship for Bragg scattering, which consists masses, derived using transfer matrix method. Subsequently, to evaluate parameters s...

The tube in flow rigs used for testing Doppler ultrasound instruments can attenuate and distort the beam and sample volume by refraction, reflection, absorption and mode conversion. The attenuation and degree of distortion has been measured by using a moving string test object and candidate tubes have been compared. Tubes of rubber, TFE-Teflon, Perspex, heatshrink and C-Flex have been tested le...

This work concerns 2D SPECT imaging with uniform attenuation in the activity region. In this paper, it is shown that exact and stable reconstruction does not require the data to be known over 360◦ as has been previously assumed. An angular range of 180◦ is sufficient in parallel-beam geometry. A reconstruction formula which uses only data on a half-turn is provided with implementation details. ...

The scattering of α-particles off of gold foil was investigated. Attenuation of the α-particle beam was used to measure the thickness of the gold foil used. The coefficient of the Rutherford differential scattering cross section was experimentally determined to be (7.81 ± 5.35) × 10−25cm2, compared to 1.76 × 10−24cm2, with a reduced chi-squared of 3.4, which is a reasonable fit and confirms the...

This study presents a generic TITOP (Two-Input Two-Output Port) model of a substructure actuated with embedded piezoelectric materials as actuators (PEAs), previously modeled with the FE technique. This allows intuitive assembly of actuated flexible substructures in large flexible multi-body systems. The modeling technique is applied to an illustrative example of a flexible beam with bonded pie...

The main objective of this study is to reduce optimal vibration suppression of Timoshenko beam under non-periodic step and impulse inputs. Cantilever beam was modeled by Timoshenko theory and finite element numerical method. Stiffness (K), mass (M), and damping (C) matrices are extracted. Then, in order to control structure vibration, piezoelectric patches were used due to simultaneous dual beh...