Fujio Hiroki

Closed loop modelling method for non-linear system using Laguerre polynomials

This paper presents a modelling method for noisy response data of a closed loop with a PI controller. A general pre-£ltering procedure is not required in this method. A three-step procedure for estimating Laplace transfer function of a process is proposed. The true closed loop response is estimated from noisy response data, exploiting orthonormal properties of Laguerre functions. Then the closed loop transfer function model (called the Laguerre model) is represented by Laplace transforms of Laguerre polynomials approximated to a true response. Lastly, the process transfer function model is computed from the Laguerre model and the PI controller. PI parameters are given by gain constant, time constant and dead time of process approximated to £rst-order lag element plus dead-time system. Using this algorithm, the process model is estimated only by the settling time of response data. Simulation and experiment results show that the proposed method is effective for non-linear systems in modelling.

In situ synthesis of titanium-aluminides in coating with supersonic free-jet PVD using Ti and Al nanoparticles

This paper presents supersonic free-jet PVD (SFJ-PVD) as a new coating technology for structural materials. In SFJ-PVD, coating film is formed by high velocity impact of solid nanoparticles to base materials. This method is composed of evaporation and deposition processes. In the evaporation process, the source material evaporates to form nanoparticles in an inert gas atmosphere. In the deposition process, nanoparticles are deposited on base materials to form coating film with supersonic gas flow. The gas flow is generated by pressure difference between the evaporation chamber and the deposition chamber. The flow of the gas is accelerated through a specially designed supersonic nozzle at the supersonic flow of 3.6 Mach number. With SFJ-PVD, mixed Ti and Al nanoparticles produce high-density coatings of titanium-aluminides without voids and cracks. They synthesize titanium-aluminides on the substrate at 800 K.

Self-sustained Oscillation Phenomena of Fluidic Flowmeters

In order to clarify the metering characteristics of the fluidic flowmeters employing selfsustained oscillation, the oscillating jets in a feedback oscillator and a target oscillator were visualized and the differential pressures across the jets were measured.The experiment clarified that the fluidic oscillators could be classified into three types, i.e., feedback type, reflection type and recirculation type oscillators. The jet oscillation was caused by external feedback control pressures in the feedback type oscillator. On the other hand, the internal feedback pressure difference, produced mainly by a partly reflected jet flow from the target, sustains the jet’s oscillation in the reflection type oscillator. In the recirculation type oscillator, the jet oscillation was caused by the internal feedback pressure difference produced by a jet flow recirculating along the side wall of the target oscillator under the influence of the reflected jet flow.The jet oscillation of the target oscillator was influenced by forced pulsation of the jet flow as follows. The strength of the reversed jet flow and reflected jet flow was affected directly with the pulsation of the jet and a synchronization phenomenon appeared, in which the oscillation frequency was matched with the pulsation frequency of the jet flow.The ranges of dimensional parameters maintaining the oscillation of the target oscillator were revealed. It was found that the target oscillator with crescent target could produce steady oscillation in a wider region of dimensional parameters.

Thermal MIMO model and decoupling PID control

This paper presents a multi-input multi-output (MIMO) thermal model and the decoupling PID parameters for a commercialised temperature controller. The PID tuning can be performed by using the physical parameters. In addition, the problem of decoupling control is described. An improvement strategy based on robust observer is also presented in the extruder experiment results.

Fabrication of nanostructure composites in functionally graded coatings with supersonic free-jet PVD

Graded Al/AlTi and Al/Al-Si coatings are prepared by depositing nanoparticles with supersonic free-jet PVD (SFJ-PVD). The SFJ-PVD has been developed as a new coating method in which a coating film is formed by depositing nanoparticles with very high velocity onto a substrate. The high velocity of nanoparticles is produced by the supersonic gas flow of inert gas. A smooth, compact and defect-free microstructure is formed both at the interface between substrates and coating films and inside the coating films. The microstructures of Al/AlTi and Al/Al-Si coating films have very fine grain size. Mixing Ti and Al nanoparticles by depositing them onto a substrate produces in-situ syntheses of g-TiAl and a2-Ti3Al intermetallic compounds on the substrate. It is confirmed with nano-indentation hardness tester that graded coatings have graded hardness corresponding to the gradation of composition.

In-vitro study on apatite/titanium composite coatings with supersonic free-jet PVD

Abstract Hydroxyapatite (HAp) has many applications in the medical field. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated to the supersonic flow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated body fluid.

Coating with supersonic free-jet PVD

Recently, requirements for structural materials become increasingly severe. A coating is one of the most promising methods to achieve the requirements. However, conventional coating processes generally have technical problems. We apply Supersonic Free-Jet PVD (SFJ-PVD) to coating. The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film without a crack or a void. This method is composed of “gas evaporation” and “vacuum deposition”. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated through a supersonic nozzle. With SFJPVD, We obtain uniform several hundreds micron meter-thick, high-density coatings.