Study of optimization design criteria for stand-alone hybrid renewable power systems

Hybrid renewable power systems integrate two or more sources of energy, one of which is renewable, optionally a storage system and typically work in stand-alone mode. They are being considered more and more and we should increment their usage taking advantage of their positive benefits: free of charge resource availability, CO2 emissions reductions and subsidies. Dealing with their inconveniences: variability of renewable resources availability and cost acquisition, through the optimization of the design and the control of the system. The optimal design of hybrid renewable power systems is usually defined by economic criteria. But there are also technical and environmental criteria to be taken into account to improve decision-making. In this paper a discussion on different criteria will introduce the non-economical perspectives in addition to the economic criteria. A case study of a PV-Wind-Diesel-Battery system for a Telecommunication station in Catalonia is discussed. Availability of renewable energy sources is obtained with RETScreen and PVSyst. Analysis and simulations of various hybrid power systems have been done in HOMER resulting on a comparison of different scenarios. Optimal scenario taking into account the best results of all three types of criteria: economic, technical and environmental, is a trade-off of the economic optimum.Postprint (published version

Study of optimization design criteria for stand-alone hybrid renewable power systems

Hybrid renewable power systems integrate two or more sources of energy, one of which is renewable, optionally a storage system and typically work in stand-alone mode. They are being considered more and more and we should increment their usage taking advantage of their positive benefits: free of charge resource availability, CO2 emissions reductions and subsidies. Dealing with their inconveniences: variability of renewable resources availability and cost acquisition, through the optimization of the design and the control of the system. The optimal design of hybrid renewable power systems is usually defined by economic criteria. But there are also technical and environmental criteria to be taken into account to improve decision-making. In this paper a discussion on different criteria will introduce the non-economical perspectives in addition to the economic criteria. A case study of a PV-Wind-Diesel-Battery system for a Telecommunication station in Catalonia is discussed. Availability of renewable energy sources is obtained with RETScreen and PVSyst. Analysis and simulations of various hybrid power systems have been done in HOMER resulting on a comparison of different scenarios. Optimal scenario taking into account the best results of all three types of criteria: economic, technical and environmental, is a trade-off of the economic optimum

Study of optimization design criteria for stand-alone hybrid renewable power systems

Hybrid renewable power systems integrate two or more sources of energy, one of which is renewable, optionally a storage system and typically work in stand-alone mode. They are being considered more and more and we should increment their usage taking advantage of their positive benefits: free of charge resource availability, CO2 emissions reductions and subsidies. Dealing with their inconveniences: variability of renewable resources availability and cost acquisition, through the optimization of the design and the control of the system. The optimal design of hybrid renewable power systems is usually defined by economic criteria. But there are also technical and environmental criteria to be taken into account to improve decision-making. In this paper a discussion on different criteria will introduce the non-economical perspectives in addition to the economic criteria. A case study of a PV-Wind-Diesel-Battery system for a Telecommunication station in Catalonia is discussed. Availability of renewable energy sources is obtained with RETScreen and PVSyst. Analysis and simulations of various hybrid power systems have been done in HOMER resulting on a comparison of different scenarios. Optimal scenario taking into account the best results of all three types of criteria: economic, technical and environmental, is a trade-off of the economic optimum

Validity and Applicability of the Global Leadership Initiative on Malnutrition (GLIM) Criteria in Patients Hospitalized for Acute Medical Conditions

(1) Background: The objectives of this study were to evaluate the concurrent and predictive validity and the applicability of the global leadership initiative on malnutrition (GLIM) criteria in patients hospitalized for acute medical conditions. (2) Methods: prospective cohort study with patients hospitalized for acute medical conditions. For validation, the methodology proposed by the GLIM group of experts was used. Sensitivity and specificity values greater than 80% with respect to those for the subjective global assessment (SGA) were necessary for concurrent validation. The time necessary to complete each nutritional assessment test was determined. (3) Results: A total of 119 patients were evaluated. The SGA was applied to the entire cohort, but the GLIM criteria could not be applied to 3.4% of the patients. The sensitivity and specificity of the GLIM criteria with respect to those for the SGA to detect malnutrition were 78.0 and 86.2%, respectively. The GLIM predictive validity criterion was fulfilled because patients with malnutrition more frequently had a hospital stay >10 days (odds ratio of 2.98 (1.21–7.60)). The GLIM criteria required significantly more time for completion than did the SGA (p = 0.006). (4) Conclusion: The results of this study do not support the use of the GLIM criteria over the SGA for the diagnosis of malnutrition in patients hospitalized for acute medical conditions

Validity and Applicability of the Global Leadership Initiative on Malnutrition (GLIM) Criteria in Patients Hospitalized for Acute Medical Conditions

(1) Background: The objectives of this study were to evaluate the concurrent and predictive validity and the applicability of the global leadership initiative on malnutrition (GLIM) criteria in patients hospitalized for acute medical conditions. (2) Methods: prospective cohort study with patients hospitalized for acute medical conditions. For validation, the methodology proposed by the GLIM group of experts was used. Sensitivity and specificity values greater than 80% with respect to those for the subjective global assessment (SGA) were necessary for concurrent validation. The time necessary to complete each nutritional assessment test was determined. (3) Results: A total of 119 patients were evaluated. The SGA was applied to the entire cohort, but the GLIM criteria could not be applied to 3.4% of the patients. The sensitivity and specificity of the GLIM criteria with respect to those for the SGA to detect malnutrition were 78.0 and 86.2%, respectively. The GLIM predictive validity criterion was fulfilled because patients with malnutrition more frequently had a hospital stay >10 days (odds ratio of 2.98 (1.21-7.60)). The GLIM criteria required significantly more time for completion than did the SGA (p = 0.006). (4) Conclusion: The results of this study do not support the use of the GLIM criteria over the SGA for the diagnosis of malnutrition in patients hospitalized for acute medical conditions