Pressure reducing valves (PRVs) are commonly used for pressure control in water distribution systems (WDSs) by means of dissipating the pressure excess. The use of pumps as turbines (PATs) is an alternative and more favorable system since they not only control the system pressure to decrease water leakage, but also utilize the pressure excess to generate electrical energy. The optimal localization of PATs can be casted into a mixed-integer nonlinear program (MINLP) where binary variables are used to represent the presence of PATs on links. Most of the available MINLP models for optimal PAT localization adopted the optimization approaches for PRV localization without considering the bound constraints on flow rates and heads of PATs. As a result, such an optimization model may make PATs delivering a non-desired output. In this paper, we propose a new MINLP model for optimal PAT localization. Instead of using a constraint on the maximum number of PATs to be placed in a WDS, new constraints relating to the minimum power generated by PAT are introduced to find links having adequate flows and head drops for placing PATs. Moreover, constraints are used to restrict flows and heads of PATs to their feasible operating range, so that the problem can be efficiently solved. The proposed MINLP model is applied to the optimal localization of PATs for a WDS benchmark and a real-world WDS in Vietnam. The results demonstrate that the new MINLP model can efficiently identify optimal locations for PAT placement where the specified working range and minimum power generated by the PATs are ensured.
Background: Wound Care (WC) plays a crucial role in patient care conducted by nurses. It directly affects treatment outcomes, especially when chronic or infected wounds remain a big challenge for WC specialists and requires huge medical recourses in wound care and treatment. Objectives: This research aimed to explore the actual situation of WC conducted by nurses to inform the development of a training program based on the Vietnam’s Basic Nursing Competency Standards (VNBNCS). Settings: Eight hospitals in Vietnam. Participants: 518 nurses directly performing WC. Design: Descriptive cross-sectional study. Methods: The study was implemented from June 2020 to October 2020, and the research indicators are nurses’ mean knowledge, practice, and confidence scores. The data collection tools included: 1) a self-administered questionnaire about nurses’ general characteristics (4 items) and WC knowledge (48 items), a WC evaluation checklist (16 items), and a self-administered questionnaire about their confidence in performing WC (12 items). Data were entered using EpiData 3.1 and analyzed with SPSS 16.0. A p<0.05 was the level of significance. Results: The highest knowledge score of 1.67 ± 0.47 points was found in the item on clean WC. The highest practice score of 8.79 ± 1.20 points belonged to the item on in strict compliance with disinfection principles, compared to the lowest one of 7.58 ± 1.94 points found in the item on observing the patient’s post-WC reactions, such as pain and bleeding. Nurses who felt very confident in their bandage replacement skills formed 21.2% (110/518 nurses). Conclusion: Nurses had high mean knowledge and practice scores in all items, and nurses who were confident and highly confident in performing WC accounted for more than 50%. Keywords: nurse; wound; knowledge; practice; confidence.
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