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A decentralized control scheme with observer-based feedback controllers is developed for a class of uncertain linear plants, and it is shown that the resulting closed-loop system is reliable in the sense that the control scheme provides guaranteed stability and H/sub /spl infin//-norm bounded performance in the event of soft-type sensor and/or actuator failures as well as in the presence of parameter uncertainties. We observed that soft-type failures were additional exogenous inputs in the closed-loop system. As a result, the sensor and/or actuator failures can be tolerated in the design, which is achieved by extending the result developed by the authors (1994).

Our experiences of implementing a fault tolerant control system is reported. To enhance the reliability, a method for implementing software for the control system with dual structure in processor module is proposed and implemented. By using the multitasking function the overall software for a processor module can be divided into five tasks which includes controls and diagnostics. To achieve the control objective and fault diagnostics effectively the tasks are performed in the dual processor modules, independently. An experimental result shows that the backup processor module can be successfully substituted for the primary processor module when the latter happens to fail, while data relating the failure informations are exchanged continuously via shared memories. >

In 656 patients aged from one to 39 years, the incidence of axonal dystrophy in the gracile nucleus (ADG) is correlated with underlying diseases. The age-related incidence of ADG (minimal to severe) in these patients, 13, 53, 76 and 97% in the first, second, third, and fourth decades, respectively, is comparable to that observed by other investigators. The incidence drops to 8, 16, 31, and 60% when more than five spheroids in each gracile nucleus are taken into account. Diseases with which ADG is frequently associated vary according to the patient's age. Congenital biliary atresia and cystic fibrosis account for 71% of cases of ADG (mild to severe) in the first decade, while cystic fibrosis and malignancies account for 38 and 35% in the second decade, respectively. In the third decade, malignancies, renal diseases, cystic fibrosis, and heart diseases account for 30, 14, 12, and 12% of ADG cases, respectively, while malignancies, renal diseases, heart diseases, and diseases of digestive organs account for 30, 24, 15, and 11% in the fourth decade, respectively. The incidence of ADG also increases progressively with age, duration of the clinical course in the individual disease, or both, regardless of types of the diseases. This fact, when viewed together with the precocious development of severe ADG in patients with the malabsorption syndromes and in those with grave illnesses with protracted course leading to cachexia, seems to indicate that malnutrition represents a common factor correlated with severe ADG in the young patients. It seems to be premature at this time to disregard the hypothetical question that ADG in man is in some way related to deficiency or altered metabolism of vitamin E.

In 63 patients with malabsorption syndromes, 16 with congenital biliary atresia (BA) and 47 with cystic fibrosis (CF), axonal dystrophy in the gracile nucleus (ADG) was studied. of the 16 patients with BA, ADG of considerable severity was observed in all 10 over one year of age. of the 47 patients with CF, it was observed in 32, 61, and 80% of the cases in the first, second, and third decades, respectively. Evidence is presented that there has been a substantial decrease in the incidence of ADG in CF patients in recent years and that the decreased incidence is attributable to vitamin E (Aquasol E) therapy. The beneficial effect of vitamin E supplementation in CF patients is proffered as strong evidence that ADG in BA and CF is related to vitamin E deficiency. The present study indicates that BA and CF patients require vitamin E supplementation to maintain a normal integrity of axons related to the gracile and perhaps other sensory nuclei. Critical neurological evaluation for possible dysfunction of the sensory nuclei in these patients with malabsorption syndromes is advised.