Design of type-1 servo systems possessing prescribed stability margins using a generalized Riccati-type equation

A design method for type-1 servo systems having prescribed stability margins at the control input and error channels is presented. The former and latter stability margins affect the properties of sensitivity and robustness and the transient response characteristics, respectively. As a preliminary, a class of state feedback laws for regulators that possess a prescribed stability margin is parametrized by means of a generalized Riccati-type equation. This is applied to designing servo systems, which enables us to specify the stability margins at the above two portions. We can improve the output response of the system by the proposed design procedure and the effect is ascertained by an example. The integrity at the error channel is also investigated.     

Sampled-data optimal control of continuous systems for quadratic criterion function taking account of delayed control action

This paper is concerned with the sampled-data control of a continuous system in the situation where there exists delay for the control action after the measurement of the output at each sampling instant. The optimal control with the quadratic criterion function defined for the continuous system is adopted in this control problem. This paper shows that the problem can be transformed into the optimal control of a discrete system for the quadratic criterion function, and the variation of the control law to the sampling period and to the delay of the control action is clarified. The deterioration of cost performance with respect to delay is derived. A numerical example is also presented.     

Heat-induced Gelation of Chicken Gizzard Myosin

Chicken gizzard myosin solution formed a gel when heated above 40°C. The rigidity of the gel was constant above 65°C. Maximum pH for gel formation was 5.9 at 0.6M and 5.7 at 0.15M KCl. Higher rigidity of the myosin gel was observed at low ionic strength than at high ionic strength. Rigidities of myosin at 0.6M KCl increased by (mg/mL)^2.5 and at 0.15M (mg/mL)^{1, 4} myosin concentration. The strength of gizzard myosin gels was comparable to that of myosin gels from chicken breast muscle under similar conditions.     

Kinetics of Hydration of Monocaldum Aluminate

Hydration of CaAl₂O₄ (CA) was studied by calorimetry, analysis of the liquid phase, measurement of the combined water, and electron microscopy. During the induction period, the solution remains almost unchanged and is equilibrated temporarily with both superficially intrusion-hydrated CA particles and Al(OH)₃ gel formed by dissociation of Al(OH)₄^– ions, the solubility of the Al(OH)₃ gel being 10^–4.24 molkg^–1 at 25°C, while the intrusion-hydrated layer on the CA particles grows following a nearly linear law to reach a critical thickness (∼3 nm at 10° to 20°C, or 12 nm at 30°C). At this point destruction of the layer occurs, nuclei of hydrous compounds are generated, and the induction period terminates. Subsequent reaction proceeds in accordance with the rate equation of Schiller based on the dissolution-crystallization mechanism.     

Schwarzschild microscopes in vacuum ultraviolet and soft X-ray regions

Microscopes in vacuum ultraviolet and soft X-ray regions using a normal incidence type of Schwarzschild objective are reviewed. The objective consists of a concave mirror and a convex mirror coated with a high reflectance multilayer, having a large numerical aperture comparing with other objectives. The microscopes have been used to diagnose inertia-confinement-fusion plasmas, and to investigate small samples or microstructures of inorganic and organic materials by imaging them using laboratory light sources. Synchrotron radiation has been also used to obtain a microbeam for a photoelectron scanning microscope with a spatial resolution of 0.1 μm. The structure and performance of two laboratory microscopes developed at Tohoku University are demonstrated. One of them is a soft X-ray emission imaging microscope, An image of an artificial pattern made of W and SiO2 on Si wafer by focusing Si L emission was presented, The other is an ultraviolet photoelectron scanning microscope using a He (helium) gas discharge lamp. The valence band spectra of a microcrystal of FeWO4 were presented, Furthermore other applications such as demagnifying optics for lithography and optics to gather fluorescence for emission spectroscopy are introduced.     

Pore Structure of Calcium Silicate Hydrate in Hydrated Tricalcium Silicate

Adsorption of N₂ and water vapor was studied in completely hydrated tricalcium silicate and in fully hydrated tricalcium silicate from which Ca(OH)₂ had been extracted. Compared with results obtained using N₂, water vapor adsorption led to increased values for small-pore volume, peak shifts to smaller sizes, and decreased values for large-pore volume. Marked hysteresis was observed in the case of water vapor adsorption; the resorption branch apparently represents the true pore structure. Extraction of Ca(OH)₂ from the paste increased the calculated volume of small pores strikingly, suggesting that adsorption is hindered by Ca(OH)₂; this tendency is more obvious in water vapor adsorption. The adsorption measurements indicate the existence of two kinds of pores, i.e. a wider intergel-particle pore and a smaller pore existing within the gel particle. The latter pore was further classified into intercrystallite and intracrystallite pores.     

Reactivities of Various Silicates with Calcium Hydroxide and Water

The reactivity of oxides and silicates with alkaline solutions is especially important in cement chemistry and is closely related to the pozzolanic reaction, the alkali-aggregate reaction, and to glass fiber reinforcement of hardened cement. Thus, the rate of the hydration reaction between several silicates and Ca(OH)₂ or portland cement at 20° and 80°C was studied. Results showed that essentially high reactivity in the reaction with Ca(OH)₂ was found in Italian pozzolan, metakaolin, and silica gel in which the first two have very high Blaine surface areas. The pozzolanic reaction of typical oxides and silicates was considered from a thermodynamic point of view.     

Study on Lightning Protection Measures for Distribution Lines and Customer Equipment against Back Flow Lightning Current from Radio Communication Station

Recently, with the expansion of communication network areas, the number of radio communication stations built in the neighborhood of customer houses has increased. If lightning strikes a communication radio tower, part of the lightning current flows into the distribution line and into customer houses. This may cause the failure of distribution lines or customer equipment. To protect distribution lines and customer equipment from lightning faults, it is necessary to analyze the surge phenomena in distribution lines and customer equipment and take appropriate protection measures. In this study, we examined the effect of lightning protection measures for distribution lines and customer equipment against lightning strikes to a communication tower. First, using an actual‐scale test distribution line, we measured the lightning current flowing into distribution lines and customer equipment. Second, we quantitatively examined the effect of lightning protection measures by lighting surge analysis while changing each parameter. From the experimental and analytical results, we show that the proposed protection measures can reduce the lightning current flowing into distribution lines and customer equipment.     

基于应变设计的大应变X100管线钢的成分设计与开发

介绍了日本新日铁公司开发的适用于基于应变设计的大应变低Mo含量高强度X100管线钢的成分设计,在实验室研究了Mo和Cr对强化能力的影响,并进行了低Mo含量16 mm厚度X100管线钢管的试生产。研究了试生产的低Mo含量X100大应变管线钢管热力时效前后的力学性能,如落锤撕裂试验性能以及母材和焊缝区的V形缺口夏比冲击性能等。试验结果表明,试生产的低Mo含量X100大应变管线钢管具有优异的低温韧性和焊缝韧性。     

High-intensity laser-driven particle and electromagnetic wave sources for science, industry, and medicine

We simultaneously observed both the fast proton generation and terahertz (THz) radiation in the laser pulse interaction with a thin-foil target.The maximum proton energy of ～2.3 MeV and an intense THz radiation were observed at the pulse duration of ～30fs.We also measured the proton beam and UV harmonics from a thin-foil target by changing the laser pulse duration.In the case of the ～500 fs, peaks of UV harmonics up to fourth order appeared.This unique combination of the multiple beams will provide useful applications such as pump-probe experiments.