This paper presents a cell to measure the dynamic viscosity of liquids using a wave mode conversi... more This paper presents a cell to measure the dynamic viscosity of liquids using a wave mode conversion from longitudinal to shear waves and vice-versa. The method is based on the measurement of the complex reflection coefficient of shear waves at a solid-liquid interface. The reflected waves are measured in the longitudinal mode by a large aperture PVDF (Polyvinylidene Fluoride) membrane. Measurements of the viscosity of automotive oils (SAE90 and SAE140) and corn glucose were made in the range from 1 to 5 MHz. The experimental results are compared with the Maxwell model with two relaxation times
ABSTRACT Measurements of ultrasonic attenuation and velocity in milk and low concentration water-... more ABSTRACT Measurements of ultrasonic attenuation and velocity in milk and low concentration water-in-oil (W/O) emulsion were conducted, using a measurement cell with a double-element transducer that eliminates diffraction losses. The milk is characterized by the attenuation coefficient, while in the case of water-in-oil emulsions, the characterization is best represented by the propagation velocity
This work presents an USBL Acoustic Positioning System developed for an underwater vehicle. The p... more This work presents an USBL Acoustic Positioning System developed for an underwater vehicle. The position, estimation is based on time-of-arrival (TOA) estimation of acoustic signals traded between a transponder and a transducer array placed on the vehicle. Modulated Barker-coded signals are used to achieve low ambiguity. Real-time DSP is implemented in a Programmable Logic Device. The TOA estimator uses a
ABSTRACT This paper presents an ultrasonic method to measure small concentrations of water in lub... more ABSTRACT This paper presents an ultrasonic method to measure small concentrations of water in lubricating oil. It uses an ultrasonic measurement cell composed by a piezoceramic emitter (5 and 10 MHz), and a large aperture PVDF receiver that eliminates diffraction effects. The propagation velocity, attenuation coefficient and density of several samples of water-in-oil emulsion were measured. The concentrations of water of the samples were in the range of 0 to 5% in volume, and the results showed that these low concentrations can be discriminated within a resolution of 0.2% in the studied range, using the measurement of the propagation velocity.
ABSTRACT This paper presents a method to obtain the acoustic field in complex structures driven a... more ABSTRACT This paper presents a method to obtain the acoustic field in complex structures driven at a plane by a multi-layered piezoelectric transducer of simple geometry. The Finite Element Method (FEM) is used in the complex structure to compute the fields and the acoustic impedance presented to the transducer. This procedure is computer intensive, but is obtained only once for a frequency range. The electric impedance of the transducer loaded with the computed acoustic impedance is obtained with the chain matrix, a fast analytical method, and FEM. These two approaches were applied to a steel tube driven through a coupler by a power transducer. Measured and calculated electric impedances are compared
The Twelfth International Offshore and Polar Engineering Conference, 2002
ABSTRACT A test bed applied to offshore operations is being developed at the University of São Pa... more ABSTRACT A test bed applied to offshore operations is being developed at the University of São Paulo and Petrobras. The main motivation for this project is to develop a robotic system that can be adapted to specific missions in deepwater fields. The vehicle aimed to this mission is an open frame type. Dynamic positioning of the vehicle is executed through a precise acoustic navigation system together with embedded control and propulsion systems. A simulator is being developed, which includes visualization and animation resources. The software is modular, which allows for easy modeling of different types of vehicles.
This paper presents a cell to measure the dynamic viscosity of liquids using a wave mode conversi... more This paper presents a cell to measure the dynamic viscosity of liquids using a wave mode conversion from longitudinal to shear waves and vice-versa. The method is based on the measurement of the complex reflection coefficient of shear waves at a solid-liquid interface. The reflected waves are measured in the longitudinal mode by a large aperture PVDF (Polyvinylidene Fluoride) membrane. Measurements of the viscosity of automotive oils (SAE90 and SAE140) and corn glucose were made in the range from 1 to 5 MHz. The experimental results are compared with the Maxwell model with two relaxation times
ABSTRACT Measurements of ultrasonic attenuation and velocity in milk and low concentration water-... more ABSTRACT Measurements of ultrasonic attenuation and velocity in milk and low concentration water-in-oil (W/O) emulsion were conducted, using a measurement cell with a double-element transducer that eliminates diffraction losses. The milk is characterized by the attenuation coefficient, while in the case of water-in-oil emulsions, the characterization is best represented by the propagation velocity
This work presents an USBL Acoustic Positioning System developed for an underwater vehicle. The p... more This work presents an USBL Acoustic Positioning System developed for an underwater vehicle. The position, estimation is based on time-of-arrival (TOA) estimation of acoustic signals traded between a transponder and a transducer array placed on the vehicle. Modulated Barker-coded signals are used to achieve low ambiguity. Real-time DSP is implemented in a Programmable Logic Device. The TOA estimator uses a
ABSTRACT This paper presents an ultrasonic method to measure small concentrations of water in lub... more ABSTRACT This paper presents an ultrasonic method to measure small concentrations of water in lubricating oil. It uses an ultrasonic measurement cell composed by a piezoceramic emitter (5 and 10 MHz), and a large aperture PVDF receiver that eliminates diffraction effects. The propagation velocity, attenuation coefficient and density of several samples of water-in-oil emulsion were measured. The concentrations of water of the samples were in the range of 0 to 5% in volume, and the results showed that these low concentrations can be discriminated within a resolution of 0.2% in the studied range, using the measurement of the propagation velocity.
ABSTRACT This paper presents a method to obtain the acoustic field in complex structures driven a... more ABSTRACT This paper presents a method to obtain the acoustic field in complex structures driven at a plane by a multi-layered piezoelectric transducer of simple geometry. The Finite Element Method (FEM) is used in the complex structure to compute the fields and the acoustic impedance presented to the transducer. This procedure is computer intensive, but is obtained only once for a frequency range. The electric impedance of the transducer loaded with the computed acoustic impedance is obtained with the chain matrix, a fast analytical method, and FEM. These two approaches were applied to a steel tube driven through a coupler by a power transducer. Measured and calculated electric impedances are compared
The Twelfth International Offshore and Polar Engineering Conference, 2002
ABSTRACT A test bed applied to offshore operations is being developed at the University of São Pa... more ABSTRACT A test bed applied to offshore operations is being developed at the University of São Paulo and Petrobras. The main motivation for this project is to develop a robotic system that can be adapted to specific missions in deepwater fields. The vehicle aimed to this mission is an open frame type. Dynamic positioning of the vehicle is executed through a precise acoustic navigation system together with embedded control and propulsion systems. A simulator is being developed, which includes visualization and animation resources. The software is modular, which allows for easy modeling of different types of vehicles.
Uploads
Drafts by Celso Furukawa
Papers by Celso Furukawa