Optimization of linear systems with integral control for time-weighted quadratic performance indices

The necessary conditions to be satisfied by the feedback control constructed by available variables, minimizing time-weighted quadratic performance indices for linear systems incorporating integral action, are developed using the parameter optimization technique. To remove the dependence of the solution on a reference input and an external disturbance, a performance index based on the statistical expectation and a minimax solution are considered. An algorithm based on a gradient technique is given to solve the necessary conditions of the minimax solution. Numerical examples are given to illustrate the effect of a time-weighted performance index on the transient response of the output, and they show that the integral-square-time-square error performance index is acceptable for a reference input.     

Determination of Tetrodotoxin by Capillary Isotachophoresis

A method is described for the quantification of tetrodotoxin (TTX) in crude extracts of puffer fish by capillary isotachophoresis. Conditions for isotachophoresis consisted of a leading electrolyte of 5 mM potassium acetate, pH 6.0, containing 0.2% Triton X-100 and 0.5 vol of dioxane, and a terminating electrolyte of 10 mM β-alanine adjusted to pH 4.5 with acetic acid. It was possible to quantify the TTX content of crude unfractionated puffer extracts, and obtain values similar to those obtained by mouse bioassays which are time consume.     

Electrical and mechanical properties of ZrO2(2Y)/TiN composites and laminates made from these materials

High density composites with the compositions of ZrO₂(2Y):TiN=40:60 and 70:30 mol% have been fabricated by hot isostatic pressing for 2 h at 1500°C and 196 MPa. The electrical resistivities (ρ) of the two composites are very different; showing metallic behaviour in the first case and insulating behaviour in the latter case. These properties are highly dependent on the sample texture. Laminated materials with compositions of ZrO₂(2Y)/TiN=(40:60)/(70:30)/(40:60) mol% have been prepared by hot isostatic pressing. The electrical resistivities in the perpendicular and parallel to the interface directions have been determined to be ρ⊥≈1×109 and ρ∥≈ 1×10^-6 Ωm, respectively. A residual stress of as much as ≈ 150 MPa is induced in the interfaces. The fracture toughness is greatly affected by the residual stress. This revised version was published online in November 2006 with corrections to the Cover Date.     

PMSM Sensorless Control Based on Position Estimation Correction Using All‐Pass Filters

This paper proposes a novel flux estimation method for the position sensorless control of permanent magnet synchronous motors (PMSMs). In general, the stator flux linkage for position estimation in PMSMs is obtained using the pure integration of voltages. The infinite dc gain of the pure‐integrator, however, causes numerical drifts in the obtained stator flux linkage due to the dc offset in the input of this integrator. To address this problem, a quasi‐integrator is often substituted instead of the pure integrator to restrict the dc gain, leading to another problem in which the phase characteristics vary according to the operating frequency. As a result, the ideal phase characteristics (?90° constant) cannot be held, and the position estimation performance deteriorates. Therefore, this paper proposes a phase characteristic correction method for quasi‐integrators using all‐pass filters, which achieves extremely precise estimation under transient conditions as well as in steady state.     

Experimental Services of Energy Management for Energy Users in Business Region on Miyakojima City All‐Islands EMS Demonstration Project

Smart grid and demand response (DR) had been attracting attention and evaluated in several demonstration projects. Many DR experimental results for residential and large‐scale buildings had been evaluated, while evaluation for small size buildings seems to be not enough. In this paper, a new energy service combined EMS method is proposed for small size buildings. Then results of its application to Miyako Island All‐Islands EMS Demonstration Project are introduced. The experimental services include not only DRs but also peak cutting recommendations and energy analysis reports. The results show combination of services can realize more effects than individual service. Especially the peak cutting recommendations and energy analysis reports help energy consumers to learn and understand how to save and manage energy usages that lead to effective DR potentials. Also the experimental system developed for energy data measurement and DR management as an island community EMS is intrduced.     

Thermal Degradation of Flavor Enhancers, Inosine 5'-monophosphate, and Guanosine 5'-monophosphate in Aqueous Solution

The mechanism of thermal degradation of inosine 5′-monophosphate (IMP) and guanosine (GMP) was investigated kinetically in aqueous solution as a function of pH and temperature. The degradation of IMP and GMP followed first order kinetics. The rate constants were considerably affected by pH and temperature. The half-life times at 100°C were: IMP, 8.7 hr (pH 4.0), 13.1 hr (pH 7.0), 46.2 hr (pH 9.0); GMP, 6.4 hr (pH 4.0), 8.2 hr (pH 7.0), 38.5 hr (pH 9.0). These times were shortened to about one-third by raising the temperature 10°C. The predominant degradation products were nucleosides and phosphoric acid, indicating that the main reaction of the thermal degradation was the hydrolysis of the phosphoric ester bond in the nucleotides.     

Thin Film Rheology and Tribology of Chocolate

We investigated relations between food texture and thin film properties rather than bulk properties. Such thin film rheological or‘tribological’effects may characterize physical behavior and physical perceptions of food products. Experiments were done on three chocolate samples. The Surface Forces Apparatus (SFA) proved to be effective for studying the very complex chocolate system. Very complex thin film behavior was found to be quite different for the three samples. Fat constitution and average particle size were important in determining the type of friction forces generated between shearing/sliding surfaces separated by thin films of chocolate. Such studies can help characterize specific physical qualities of chocolate.     

Ferroelectric Properties and Memory Characteristics of Pb(Zr0.52 Ti0.48)O3 Thin Films Crystallized by Hot Isostatic Pressing

Pb(Zr_0.52Ti_0.48)O₃ films with highly uniform c-axis orientation were fabricated on PbTiO₃ (PT)/ Pt(111)/SiO₂/Si(100) substrates by hot isostatic pressing (HIP) from the amorphous state. All the PZT samples HIP-treated 500°C for 1 h under gas pressures of 1.0–2.0 MPa showed the preferred (001) orientation with c-axis orientation, α > 0.80. The relative permittivity tended to decrease gently with increasing HIP pressure, whereas the dielectric loss increased almost linearly in the 1.5–100 MPa. The PZT sample treated at 1.5 MPa had a symmetric and slim hysteresis loop shape with a remanent polarization, P _r = 15 μ C/cm² and coercive field, E _c = 60 kV/cm. Both samples treated at 10 and 100 MPa exhibited almost the fatigue-free behavior that resisted degradation even after 3 × 10¹⁰ cycles.     

Glass Formation Range, Acid Resistivity, and Surface Charge Density of ZnO-B2O3-SiO2 Passivation Glass Containing Al2O3

The glass formation range in the system ZnO-B₂O₃-SiO₂ increases when 5% Al₂O₃ is added and then decreases with further Al₂O₃ additions. The acid resistivity of the glass also increases when Al₂O₃ is added. An observed increase in negative charge with Al content until the system contains equal amounts of Al and Si (in forms of mole %) is explained by the formation of AlO₄⁻ tetrahedra which substitute in the SiO₄ network. Alkaline-earth oxides cause a positive charge which compensates for the negative charge formed by Al₂O₃. Antimony oxide and lanthanum oxide result in a negative charge in the glass. The formation of a negative or positive charge in the glass is thought to reflect the acidity or basicity of the glass, respectively.