Robust and simple adaptive control system design

Recently, the simple adaptive control (SAC) method has attracted considerable interest because of the simple structure of its adaptive controller. The method can only be applied to plants with so-called almost strictly positive real (ASPR) characteristics. Unfortunately, most real plants do not satisfy this condition. Furthermore, real plants contain disturbances such as uncertain elements. This paper deals with such problems and proves that the implementation of a parallel feedforward compensator makes it possible to apply the SAC method to non-ASPR SISO plants with plant uncertainties. Furthermore, a robust SAC algorithm in the presence of a class of external disturbances is also considered. The effectiveness of the parallel feedforward compensator and robust adaptive controller designed in this way is examined through several numerical simulations.     

Diffuse alveolar hemorrhage associated with idiopathic interstitial pneumonia syndrome after allogeneic bone marrow transplantation

Atherosclerosis may represent a significant cause of death and morbidity in patients with systemic lupus erythematosus. Coronary involvement is more premature in lupus patients. We present the case of a young woman diagnosed with SLE at the age of 20 years who had a myocardial infarction at age 29 years. We review the mechanisms of atherosclerosis, the interrelations between atherosclerosis and autoimmunity, and between atherosclerosis and SLE. We also review the risk factors, influence of disease and treatment and the guidelines for management of accelerated atherosclerosis in lupus patients.     

Characterization of surface recombination velocity at Si solar cell surface under high injection level

The illumination intensity dependence on the effective lifetimes of silicon wafers with SiO₂ passivation layers is measured. A chopped CW-YAG laser light of up to 877 mW/cm² is used to accurately measure the effective lifetimes. Also, the density of interface traps of the corresponding wafers is measured, and the SRH model is used to analyze the obtained dependence of surface recombination velocity on excess carrier concentration. The fitting analysis shows that the hole capture cross-section strongly depends on the conduction type and preparation conditions. In contrast, the electron capture cross-section remains the same, regardless of the conduction type or sample preparation conditions.     

A Multivariable Optimal Control System for a Generator

A new digital generator control system has been developed, which coordinates excitation and governing systems of a generator by using multivariable optimal control scheme on the basis of modern control theory. Control performance of the developed system was investigated with computer simulations and tested at a 200KVA pilot power plant with 3KV transmission lines. This paper first outlines the control system, next describes the control schemes including process models, optimal control algorithms, control sequence, and state estimation schemes, and finally shows its control performance obtained from the pilot plant tests and the computer simulations.     

The outcome of patients with mediastinal tumors detected by mass screening versus the outcome of those initially presentating with symptoms

Forty seven patients with mediastinal tumors, who were diagnosed between 1976 and 1996 at Tsukuba University Hospital, were evaluated according to the circumstances surrounding their initial consultations. The outcome of 19 patients (40.4%) whose tumors were detected by mass screening was compared with the outcome of 20 patients (42.6%) whose tumors were detected after presenting with symptoms. In the mass screening group, only 21% of the patients had a malignant neoplasm, whereas 75% of patients in the symptomatic group had a malignant neoplasm (p = 0.0008). Patients in the screening group had a shorter hospital stay than those in the symptomatic group (60.5 vs. 118. 1days; p = 0.0022). In patients with thymomas, in the mass screening all patients group were at stage I or II. Only 20% of the lesions in symptomatic patients were at stage I or II (p < 0.0001). Based on the results of this study, we believe that the early detection of mediastinal tumors via mass screening might have clinical significance.     

Surgical treatment of gastric cancer detected by mass screening

BACKGROUND/AIMS: It is crucial to improve the postoperative prognosis of patients with gastric cancer in geographic regions where the incidence of gastric cancer is high. This study compared the efficacy of surgical treatment in patients with gastric cancer detected by a mass screening survey with that of patients diagnosed in accordance with standard medical practice. METHODOLOGY: The subjects included 189 patients with gastric cancer detected by a mass screening survey (screening group) who underwent surgical treatment from 1988 to 1995, and 517 patients who underwent a standard medical work-up (non-screening group). RESULTS: The incidence of early gastric cancer, curative resectability rate, and 5-year survival rates between the screening and non-screening groups were 73.0% versus 48.4% (p < 0.01), 90.5% versus 66.7% (p < 0.01), and 86.2% versus 61.0% (p < 0.01), respectively. CONCLUSIONS: Surgical treatment for patients with gastric cancer identified by mass screening is effective in saving lives and reduces the mortality from gastric cancer in the target population of mass screening. However, a further prospective randomized controlled study of this screening method will be necessary in the future.     

Observability Conditions by Polynomial Ideals

In this paper, we give global and local observability conditions of polynomial systems. Each observability is defined in terms of distinguishability of a pair of initial states. The set of pairs of initial states are represented as an affine variety. By using this affine variety, a global observability condition is derived. Then, a local observability condition is presented based on the minimal decomposition of the affine variety and dimension theory.     

Two-dimensional control of optical spatial coherence by acoustooptic interactions

A method is described for 2-D control of spatial coherence by use of multiple, crossing ultrasonic waves. If all the ultrasonic waves differ in frequency from one another, the coherence modification factor results as a product of the individual modification factor formed by each ultrasonic wave itself. Two arrangements are discussed in detail together with experimental results: one with the ultrasonic waves propagating in orthogonal directions, the other with the waves propagating in three symmetric directions. The coherence modification factor obtained from either arrangement varies periodically in space but is almost uniform in the azimuthal direction if the two-point separation concerned is taken in a linear dimension a little larger than half of one ultrasonic wavelength.