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In this article, a virtual space vector based overmodulation algorithm is presented for three-level neutral-point (NP) clamped converters in high-speed aerospace motor drives. With the proposed inscribed polygonal-boundary compression technique, the output voltage capability is enhanced under a lower crossover angle and compression coefficient. As a result, it brings an opportunity for the operation of the studied aircraft electric starter/generator (ESG) systems easily extending from the linear modulation range into the overmodulation region. Furthermore, an active capacitor voltage balancing control method is investigated to recover NP potential imbalance in the case of high modulation index and low power factor operating conditions. To simplify the digital implementation of the algorithm, a fast calculation approach is adopted in this work. The modulation performance of the proposed strategy is verified by both simulation and experimental results with a 45 kW, 32 k r/min ESG prototype system. [ABSTRACT FROM AUTHOR]

Mobile-based advisory services have significant benefits, including access to agricultural information, knowledge sharing, meteorological information, marketing-related information, and financial services for smallholder farmers. This study aimed to assess farmers' information behavior regarding mobile-based advisory services and how farmers with different characteristics and attitudes access and adopt information. Data were collected from 382 farmers in Dakhalia governorate, Egypt. The most frequently received information was related to best agricultural practices, weather forecasts, seed varieties and treatment, and water management. Cluster analysis revealed that 47% of the farmers had low information behavior. Seventy-one of the respondents had a favorable attitude toward information retrieval from mobile agricultural services. The information behavior groups of the farmers significantly differed in education, farm size, diversity of agricultural production, and attitude regarding trust and quality of the information provided. Information behavior among farmers has useful implications for policymakers in supporting the long-term benefits of mobile-based advisory services. [ABSTRACT FROM AUTHOR]

This research aimed to 1) explore the organizational climate of the agricultural extension in New Valley Governorate, 2) explore the status quo of job satisfaction and commitment of extension personnel in the New Valley Governorate, and 3) investigate the impact of agricultural extension organizational climate on job satisfaction and commitment of extension personnel. Data were collected using the questionnaire form during January to February 2021, from a sample of 25 Extension personnel representing 37.3% of their total number in New Valley Governorate (67 Personnel). Frequencies, mean, standard deviation and stepwise regression analysis were used for data presentation and analysis. Findings revealed that the respondents’ perceptions overall mean score of the organizational climate reached 68.26% of the total score, their job satisfaction is 73.6% of the total score, and their organizational commitment reached 68.4% of the total score. Findings also show that the variable of “Efficiency” contribute to the interpretation of 19.6% and 57.7% of variance of the Job Satisfaction and Employees' Commitment, respectively. Other variable influenced the Job Satisfaction is “Outward Focus” which contributed 37% of the explanation of the variance of the overall Job Satisfaction. Results also revealed that the variable of " Clarity of Organizational Goals" is contributed to the interpretation of 10.7% of variance of the Job Satisfaction. Based on the previous results the null hypotheses numbers 10, 12, 13, and 31 could be rejected, while the remaining null hypotheses couldn’t be rejected. [ABSTRACT FROM AUTHOR]

Corrosion of steel bars embedded in concrete made of Portland cement replaced partially with ground limestone is studied. Three variables are considered: replacement ratios with ground limestone (0, 10, 15, 20 and 25% of cement by weight), level of cement content (300, 350 and 400 kg/m) and fineness of ground limestone (345, 530 and 720 m/kg). Reinforced concrete specimens are immersed in a 5% sodium chloride solution by weight up to 9 months. The corrosion rate is measured by potentiodynamic polarisation technique. To explain the corrosion behaviour of steel bar embedded in Portland limestone cement concrete, samples are prepared from the same concrete mixes and tested mechanically and physically. X-ray diffraction and thermogravimetric analyses of limestone cement pastes with similar replacement levels are also conducted. The corrosion rate of steel bars embedded in concrete containing ground limestone (530 m/kg or more) is found to decrease with increase of cement replacement ratio up to 25% by weight. The corrosion behaviour of steel bars and the resistivity characteristics of Portland limestone cement concrete are also found essentially to depend on the cement content of the concrete. The corrosion behaviour of steel bars in Portland limestone cement concrete, as well as the compressive strength of the concrete, is found to be strongly associated with the fineness of limestone relative to the fineness of cement. [ABSTRACT FROM AUTHOR]