An exploitation model and performance predictions for the ahuachapán geothermal field, El Salvador

Geothermics ◽  
1991 ◽  
Vol 20 (4) ◽  
pp. 181-196 ◽  
Author(s):  
Mark Ripperda ◽  
Gudmundur S. Bodvarsson ◽  
Marcelo J. Lippmann ◽  
Gustavo Cuellar ◽  
Carlos Escobar
1991 ◽  
Author(s):  
M. Ripperda ◽  
G.S. Bodvarsson ◽  
M.J. Lippmann ◽  
P.A. Witherspoon ◽  
C. Goranson

1991 ◽  
Author(s):  
M. Ripperda ◽  
G.S. Bodvarsson ◽  
M.J. Lippmann ◽  
P.A. Witherspoon ◽  
C. Goranson

Geothermics ◽  
1997 ◽  
Vol 26 (5-6) ◽  
pp. 657-680 ◽  
Author(s):  
Marco A. Perez Flores ◽  
Enrique Gómez Treviño

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A84-A85 ◽  
Author(s):  
L P Schwartz ◽  
J K Devine ◽  
S R Hursh ◽  
E Mosher ◽  
S Schumacher ◽  
...  

Abstract Introduction Fatigue and its effects on performance have long been a concern in medicine. Evidence exists that current duty-hour restrictions for resident trainees have a limited impact on physician wellbeing and patient safety, prompting renewed efforts to address this threat. In this study, sleep patterns of general-surgery residents were used to optimize a biomathematical model of performance for use as a tool for fatigue risk management with residents. Methods General surgery residents based at a multi-hospital, general surgery residency program were approached for participation in this study. Enrolled residents wore actigraph devices for 8 weeks and completed subjective sleep assessments. Sleep data and shift schedules were then input into the Sleep, Activity, Fatigue and Task Effectiveness (SAFTE) Model to assess predicted cognitive performance. Performance was compared to an “effectiveness” level of 77 (equivalent to a blood-alcohol content of 0.05g/dL). Eight hours of sleep debt was considered “below reservoir criteria”. Results Sleep actigraphy data was collected from 22 general surgery residents. Modeling results showed that as shift lengths increased, effectiveness scores generally decreased, and the time spent below criterion (77) increased. Additionally, 11.13% of time on shift was below the effectiveness criterion and 42.7% of shifts included time spent below the reservoir criterion. Adjustments to the sleep prediction were made based on actual sleep, and performance predictions from actual sleep and the adjusted model were significantly correlated (p<.0001). Conclusion Despite adherence to national standards limiting work hours, current surgical resident sleep patterns and shift schedules create concerning levels of fatigue. This study illustrates how biomathematical fatigue models can predict resident physician sleep patterns and performance. Modeling represents a novel and important tool for medical educators seeking to create shift schedules that maintain physician preparedness and minimize fatigue risk. Support N/A


2019 ◽  
Vol 30 (4) ◽  
pp. 606-617 ◽  
Author(s):  
Gang Wang ◽  
Jinwei Shen

In this article, a nonlinear model was developed for a cantilevered piezoelectric pipe conveying fluid that included geometric nonlinearity and electromechanical coupling. The Galerkin method discretized the system in order to characterize its behavior. Critical flutter velocity and its associated unstable mode can be determined based on linear analysis. Due to the presence of piezoelectric materials, the critical flutter velocity depends on the resistive piezoelectric damping and electromechanical coupling. This added resistive piezoelectric damping tends to decrease the flutter velocity. Comprehensive simulations were also conducted to characterize the post-flutter behaviors. System parameters including amplitude, deformed pipe shape, and collected voltage in piezoelectric materials were calculated. The system will undergo limited cycle oscillation when the fluid velocity passes the flutter velocity. Parametric studies were conducted as well to investigate the system responses under different flow velocities. Physical insights can be collected from these simulation results to conduct piezoelectric pipe design and performance predictions for future pipe vibration control and energy harvesting applications.


Sign in / Sign up

Export Citation Format

Share Document