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In this paper we conducted an experimental study to evaluate the impact of soiling on the temperature and electricity production of two photovoltaic technologies (Poly-Si and CdTe) under a hot semi-arid climate of Morocco. For this purpose, two modules -from each technology-were exposed for one year where one is cleaned every day and the other is left to accumulate soiling on its surface. In parallel, the electrical parameters, the weather data and the modules temperature were monitored using high precision instruments. Results show that the Poly-Si technology is highly affected by soiling in comparison to the CdTe where the measured daily Soiling ratio (SR) can reach 0.70 and 0.73 respectively. This values lead to a drop on the energy production of 15% for the Poly-Si and 13%. Regarding the modules temperature (Tm) results show that soiling has an impact on increasing the temperature for both technologies, but the Poly-Si module is more affected than the CdTe one, where the daily average temperature difference between the clean and the soiled modules is around 1.5 °C and 1.3 °C for both technologies, respectively.
RESUMO
OBJECTIVE: The present study was conducted to estimate vaccination coverage against hepatitis B virus and the perceptions of 1198 medical sciences students in Sana'a City, Yemen. METHODS: Only those who practice clinical training or are in contact with body fluids were included. The students were enrolled in the Faculty of Medicine and Health Sciences, Sana'a University, Republic of Yemen. Data was collected from 1999-2000. Arabic pre-tested questionnaire forms were completed by 840 students at a response rate of 70.6%. RESULTS: The study revealed a reported vaccination rate of 29.5%. The rate among Faculty of Medicine and Health Sciences students was 32.3%, whereas only 21.3% among the students of High Institute of Health Sciences. Students of dentistry attained the highest rate of vaccination (38.8%), while nursing students of the High Institute of Health Sciences achieved the lowest rate (17.1%). Rate of vaccination (46.6%) among female students was significantly higher than male students (22.3%) with a P- value of 0.0001. Medical assistants of the High Institute of Health Sciences scored the best (56%) in terms of knowledge, medical laboratory sciences students achieved the highest (43.6%) in attitude and dentistry students had the highest scores (35.5%) in practices. The mean knowledge of females and males was comparable, however, females achieved higher attitudes and practices. Final stage students attained better attitude scores than the pre-final and intermediate students. CONCLUSION: Vaccination coverage of medical sciences students in Sana'a City, Yemen is low. Knowledge of medical assistants is the best, attitude of medical laboratory sciences students and practices of dental students is the highest. Attitudes and practices of female students are better than that of males.
