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The wind turbine blade is an important component for harnessing wind energy. It plays a vital role in wind turbine operation. In this work, a study was conducted to investigate the dynamic behavior of an optimal rotary wind turbine blade with a bond graph approach simulated with MATLAB/Simulink. The model is considered as a twisted Rayleigh beam which is made of several sections of the type SG6043 airfoil. This type of airfoil is suitable for low wind conditions, and each section is subjected to aerodynamic loads that are computed using the blade element momentum theory. The bond graph model was developed based on the law of conservation of mass and energy in the systems, and then the model was converted to the MATLAB/Simulink toolbox; results were validated with SG6043 airfoil data and real wind data collected from selected specific sites of Abomsa, Metehara, and Ziway areas in Ethiopia.

The wind turbine blade is an important component for harnessing wind energy. It plays a vital role in wind turbine operation. In this work, a study was conducted to investigate the dynamic behavior of an optimal rotary wind turbine blade with a bond graph approach simulated with MATLAB/Simulink. The model is considered as a twisted Rayleigh beam which is made of several sections of the type SG6043 airfoil. This type of airfoil is suitable for low wind conditions, and each section is subjected to aerodynamic loads that are computed using the blade element momentum theory. The bond graph model was developed based on the law of conservation of mass and energy in the systems, and then the model was converted to the MATLAB/Simulink toolbox; results were validated with SG6043 airfoil data and real wind data collected from selected specific sites of Abomsa, Metehara, and Ziway areas in Ethiopia.

The distribution transformer plays an important role in the distribution of electric energy to the customers. The reliability of DT does not only affect availability of the electric power to the customers of utility, but also economical operation of a utility. They can operate up to 30 years; but they fail within a year, due to many reasons resulting big economic and service lose on the power supplying utilities as well as the power customers. This paper has exposed the root causes of failure of the distribution transformer in EEU Dessie district Kombolcha NO. 1 and No. 2-customer service centers by using data collected from the substation, EEU, and inspecting the status of some transformers at peak hours. From the analysis conducted it was observed that the most frequently occurring causes of failure of distribution transformers in the centers were overloading, uneven power overloading, external short circuit, and lightning. In addition to identifying the causes, the researchers have proposed some remedial solutions to reduce the problems.

The distribution transformer plays an important role in the distribution of electric energy to the customers. The reliability of DT does not only affect availability of the electric power to the customers of utility, but also economical operation of a utility. They can operate up to 30 years; but they fail within a year, due to many reasons resulting big economic and service lose on the power supplying utilities as well as the power customers. This paper has exposed the root causes of failure of the distribution transformer in EEU Dessie district Kombolcha NO. 1 and No. 2-customer service centers by using data collected from the substation, EEU, and inspecting the status of some transformers at peak hours. From the analysis conducted it was observed that the most frequently occurring causes of failure of distribution transformers in the centers were overloading, uneven power overloading, external short circuit, and lightning. In addition to identifying the causes, the researchers have proposed some remedial solutions to reduce the problems.

This paper presents a selective survey of papers, books, and reports that articulate recent trends of Security Constrained Economic Dispatch (SCED) of integrated renewable energy systems (IRES). The time-period under consideration is 2008 through 2020. This is done to provide an up-to-date review of the recent, major advancements in the SCED, and state-of-the-art since 2008. This helps identify further challenges needed in adopting smarter grids, and indicate ways to address these challenges. The study was conducted in three areas of interest that are relevant for articulating the recent trends of SCED. These areas are (i) SCED of power systems with IRES, (ii) SCED mathematical formulation and solution methods, and (iii) SCED challenges. The review results and research directions deduce that the state of the art research is not enough and needs special attention on following the path of artificial intelligence-based optimization.

This paper presents a selective survey of papers, books, and reports that articulate recent trends of Security Constrained Economic Dispatch (SCED) of integrated renewable energy systems (IRES). The time-period under consideration is 2008 through 2020. This is done to provide an up-to-date review of the recent, major advancements in the SCED, and state-of-the-art since 2008. This helps identify further challenges needed in adopting smarter grids, and indicate ways to address these challenges. The study was conducted in three areas of interest that are relevant for articulating the recent trends of SCED. These areas are (i) SCED of power systems with IRES, (ii) SCED mathematical formulation and solution methods, and (iii) SCED challenges. The review results and research directions deduce that the state of the art research is not enough and needs special attention on following the path of artificial intelligence-based optimization.

The objectives of this study were to identify the breeding objectives of Begaria cattle keepers. A semi-structured questionnaire, live animal ranking, and focus group discussions were employed to identify the breeding objectives of the farmers. The study was conducted on a total of 75 conveniently sampled households. Among the total cattle population of the sampled households, 506 heads of cattle (252 male and 254 female animals) were ranked as first best, second best, third best, and/or the worst animals. Owners were asked to choose the first best, second best, third best, and worst animals from their herd for both sexes. Reasons for ranking, important morphometric measurements, and (re)production performance of the ranked animal were taken. The R Commander package version 2.6-0 was used to analyze qualitative data and analysis of variance in R software was used to analyze quantitative data. Reasons for ranking of cows in the study area were milk yield (39.14%), calving interval (15.14), temperament (12), and body size (10.86), whereas for bulls, reasons were body size (30.39%), growth (30.66), body condition score (16.85), and color (15.19). Survival rate (Sur), calving interval (CI), milk yield (MY), and lactation milk yield (LMY) for the cows and body condition score (BCS), weaning age (WA), yearling weight (YW), and weaning weight (WW) for the bulls were significantly different (p < 0.05) mainly between the first- and last-ranked animals. Farmers were willing to pay up to Ethiopian birr (ETB) 11,500, 10,700, 10,400, and 9500 on average for first-, second-, and third-ranked breeding females and up to ETB 6300, 5800, 5200, and 4500 for breeding males. Lactation milk yield, calving interval, mothering ability, growth rate, and age at first calving were determined as breeding objective traits of the community. with suggested selection criteria of lactation milk yield, calving interval, survival rate, yearling weight, and age at first calving, respectively.

The objectives of this study were to identify the breeding objectives of Begaria cattle keepers. A semi-structured questionnaire, live animal ranking, and focus group discussions were employed to identify the breeding objectives of the farmers. The study was conducted on a total of 75 conveniently sampled households. Among the total cattle population of the sampled households, 506 heads of cattle (252 male and 254 female animals) were ranked as first best, second best, third best, and/or the worst animals. Owners were asked to choose the first best, second best, third best, and worst animals from their herd for both sexes. Reasons for ranking, important morphometric measurements, and (re)production performance of the ranked animal were taken. The R Commander package version 2.6-0 was used to analyze qualitative data and analysis of variance in R software was used to analyze quantitative data. Reasons for ranking of cows in the study area were milk yield (39.14%), calving interval (15.14), temperament (12), and body size (10.86), whereas for bulls, reasons were body size (30.39%), growth (30.66), body condition score (16.85), and color (15.19). Survival rate (Sur), calving interval (CI), milk yield (MY), and lactation milk yield (LMY) for the cows and body condition score (BCS), weaning age (WA), yearling weight (YW), and weaning weight (WW) for the bulls were significantly different (p < 0.05) mainly between the first- and last-ranked animals. Farmers were willing to pay up to Ethiopian birr (ETB) 11,500, 10,700, 10,400, and 9500 on average for first-, second-, and third-ranked breeding females and up to ETB 6300, 5800, 5200, and 4500 for breeding males. Lactation milk yield, calving interval, mothering ability, growth rate, and age at first calving were determined as breeding objective traits of the community. with suggested selection criteria of lactation milk yield, calving interval, survival rate, yearling weight, and age at first calving, respectively.