PubMed Health⌕ Search

Biomedical subjects

A Seco

Publications and source records attributed to A Seco.

22 records · Page 2Linked to original sources
PubMed1999

Nonlinear control of an activated sludge aeration process: use of fuzzy techniques for tuning PID controllers.

In this paper, several tuning algorithms, specifically ITAE, IMC and Cohen and Coon, were applied in order to tune an activated sludge aeration PID controller. Performance results of these controllers were compared by simulation with those obtained by using a nonlinear fuzzy PID controller. In order to design this controller, a trial and error procedure was used to determine, as a function of error at current time and at a previous time, sets of parameters (including controller gain, integral time and derivative time) which achieve satisfactory response of a PID controller actuating over the aeration process. Once these sets of data were obtained, neural networks were used to obtain fuzzy membership functions and fuzzy rules of the fuzzy PID controller.

Algorithms↗
PubMed1995

[The epidemiology of proximal femur fracture at the Hospital da Horta (Azores)].

The aim of this study was to know the incidence of osteoporotic hip fracture in a defined area of the Azores. The catchment area included the islands of Faial, Pico, Flores and Corvo, with 11,617 subjects aged 50 or more: 5,373 males and 6,244 females. The time period of the survey was 1991 to 1993. Data was obtained from the records of the Orthopedic Department of Hospital Horta. Thirty seven fractures were diagnosed during the time survey: 12 in 1991, 13 in 1992 and 12 in 1993. The age-adjusted mean incidence rates of hip fracture for the population over 49 years old was 10.3/10,000: 5.6/10,000 in men and 14.4/10,000 in women. Most fractures occurred in women over the age of 65 years. The ratio of male to female cases was 1:3. The mean age of all patients was 77 +/- 8 years of age: 72 +/- 8 in males and 79 +/- 6 in females (p = 0.05). About 70 percent of these patients were treated surgically. The acute mortality rate was 8 percent and the mean age of the deceased patients, 82 +/- 6, was significantly higher than the mean age of the survivors, 73 +/- 6 (p = 0.01).

Age Distribution↗