Browsing by Author "Oberli, C"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    An expert system for monitor alarm integration
    (1999) Oberli, C; Urzua, J; Saez, C; Guarini, M; Cipriano, A; Garayar, B; Lema, G; Canessa, R; Sacco, C; Irarrazaval, M
    Objective. Intensive care and operating room monitors generate data that are not fully utilized. False alarms are so frequent that attending personnel tends to disconnect them. We developed an expert system that could select and validate alarms by integration of seven vital signs monitored on-line from cardiac surgical patients. Methods. The system uses fuzzy logic and is able to work under incomplete or noisy information conditions. Patient status is inferred every 2 seconds from the analysis and integration of the variables and a uni ed alarm message is displayed on the screen. The proposed structure was implemented on a personal computer for simultaneous automatic surveillance of up to 9 patients. The system was compared with standard monitors (Space-Labs (TM) PC2), using their default alarm settings. Twenty patients undergoing cardiac surgery were studied, while we ran our system and the standard monitor simultaneously. The number of alarms triggered by each system and their accuracy and relevance were compared. Two expert observers (one physician, one engineer) ascertained each alarm reported by each system as true or false. Results. Seventy-five percent of the alarms reported by the standard monitors were false, while less than 1% of those reported by the expert system were false. Sensitivity of the standard monitors was 79% and sensitivity of the expert system was 92%. Positive predictive value was 31% for the standard monitors and 97% for the expert system. Conclusions. Integration of information from several sources improved the reliability of alarms and markedly decreased the frequency of false alarms. Fuzzy logic may become a powerful tool for integration of physiological data.
  • Thumbnail Image
    Item
    Multi-antenna testbeds for research and education in wireless communications
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2004) Rao, RM; Zhu, WJ; Lang, S; Oberli, C; Browne, D; Bhatia, J; Frigon, JF; Wang, JM; Gupta, P; Lee, H; Liu, DN; Wong, SG; Fitz, M; Daneshrad, B; Takeshita, O
    Wireless communication systems present unique challenges and trade-offs at various levels of the system design process. Since a variety of performance measures are important in wireless communications, a family of testbeds becomes essential to validate the gains reported by theory. Wireless testbeds also play a very important role in academia for training students and enabling research. In this article we discuss a classification scheme for wireless testbeds and present example testbeds developed at UCLA for each of these cases. We present the unique capabilities of these testbeds, provide results of experiments, and discuss the role they play in an educational environment.