Ricardo Tokio Higuti

Publications (3)1.84 Total impact

• Article: Thermal Characterization of an Ultrasonic Density-Measurement Cell.

  Ricardo Tokio Higuti, Bruno Shintate Galindo, Cláudio Kitano, Flávio Buiochi, Julio Cezar Adamowski
  IEEE T. Instrumentation and Measurement. 01/2007; 56:924-930.
• Article: Ultrasonic density measurement cell design and simulation of non-ideal effects.

  Ricardo Tokio Higuti, Flávio Buiochi, Júlio Cezar Adamowski, Francisco Montero de Espinosa
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  ABSTRACT: This paper presents a theoretical analysis of a density measurement cell using an unidimensional model composed by acoustic and electroacoustic transmission lines in order to simulate non-ideal effects. The model is implemented using matrix operations, and is used to design the cell considering its geometry, materials used in sensor assembly, range of liquid sample properties and signal analysis techniques. The sensor performance in non-ideal conditions is studied, considering the thicknesses of adhesive and metallization layers, and the effect of residue of liquid sample which can impregnate on the sample chamber surfaces. These layers are taken into account in the model, and their effects are compensated to reduce the error on density measurement. The results show the contribution of residue layer thickness to density error and its behavior when two signal analysis methods are used.
  Ultrasonics 08/2006; 44(3):302-9. · 1.84 Impact Factor
• Article: Low Cost Reflective Fiber-Optic Sensor Applied to Resonance Frequencies Measurement of Flextensional Piezoelectric Actuators

  João Marcos, Salvi Sakamoto, Ricardo Tokio Higuti, Emílio Carlos, Nelli Silva, Cláudio Kitano
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  ABSTRACT: In this work it is reported the experimental analysis of a novel piezoelectric flextensional actuator (PFA), designed by the topology optimization method, using a low cost reflective fiber-optic sensor. The frequency response of the PFA was evaluated up to 27 kHz. To confirm the observed frequencies of resonance it was also utilized an impedance analyzer to measure the magnitude and phase of the PFA admittance. Introduction Piezoelectric ceramics such as PZT can convert electrical energy to mechanical form. Because the free strain or displacement (in plane: d31; out of plane: d33) of the piezoceramics is small, they generally cannot be used directly as actuators in their raw form; rather, amplification is required. Piezoelectric ceramic actuators often employ mechanical amplifiers to convert the small-induced strain of the ceramic material to a large output displacement, which can be used for practical applications. Piezoelectric actuators offer fast response time (down to microsecond time constant), shows no wear and tear because their displacement is based on solid state dynamics and have neither gears nor rotating shafts. Piezoelectric actuators are very well suited to replace conventional manual positioning elements as well as motorized systems, increasing the resolution and reducing the overall size of the systems. A very efficient d33-type actuator and compliant mechanism amplifier, designed to be used as positioners, is the so-called Piezoelectric Flextensional (Flexural - Extensional) Actuator (PFA). The theoretical treatment of the finite element (FE) method taking into account the PZT type and thickness, metallic flexible structure material and thickness, cavity depth and bonding layer can be found in reference (1). The PFA prototype is shown in Fig. 1 and the FE analysis was performed using the ANSYSTM software. In this paper a PFA designed by the topology optimization method in a previous work (2) is experimentally characterized by the measurement of its nanometric displacements using a fiber-optic displacement sensor.