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Background: since COVID-19 emergence in December 2019, health systems in collaboration with scientists all over the world struggled to face this pandemic. Population acceptance of vaccination is a very important factor necessary to achieve herd immunity. This study aimed to assess the prevalence of vaccine acceptance and its predictors among the Egyptian population. Methods: An online cross-sectional study was conducted on a total sample of 846 individuals selected by using the non-probability snowball sampling technique during August and September 2021. Data was collected by An Arabic questionnaire which included data on the socio-economic characters of the participants, health-related variables, and the outcome variable (participants' vaccine acceptance). The odds ratio and 95% confidence interval were used to identify the association between vaccine acceptance and socio-demographic and health-related variables. Results: Of 846 participants, 467 accept vaccination representing 55.2% of the total sample. Vaccine acceptance was associated with a higher age group (>50 years), male gender, urban residents, educated, married, high-income individuals, and healthcare workers. Also, vaccine acceptance was associated with a history of chronic disease, fair/poor self-rated health status, negative history of COVID-19 infection, and a high perception of the infection risk. About 83.4% of vaccine refusals believed that the vaccine is not safe, while 50.7% believed it is ineffective. Conclusion: Socio-demographic and some health-related characters are significant predicators of vaccine acceptance among the population. These variables must be taken into consideration in interventions aimed to increase the population vaccination rate. [ABSTRACT FROM AUTHOR]

This paper proposes a unified load flow (LF) model for AC–DC hybrid distribution systems (DSs). The proposed model can be applied in hybrid DSs with mixed configurations for AC/DC buses and AC/DC lines. A new classification of DS buses is also introduced for LF analysis. A set of generic LF equations has been derived based on comprehensive analysis of the possible AC–DC hybrid system configurations. Three binary matrices, which are used as a means of describing the configuration of the AC and DC buses and lines, have been employed in the construction of the unified power equations. These matrices enable a single configuration at a time to be activated in the power equations. The proposed LF model is generic and can be used for both grid-connected and isolated hybrid DSs. The new model has been tested using several case studies of hybrid DSs that include different operational modes for the AC and DC distributed generators. As a means of evaluating the effectiveness and accuracy of the proposed model, the LF solution was compared to the solution produced by PSCAD/EMTDC. A comparison of the results reveals the efficacy of the proposed model. [ABSTRACT FROM AUTHOR]