Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pande...Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.展开更多
This paper examines the growth of ZnO thin films on glass substrate at 350 ℃ using an ultrasonic spray technique. We have investigated the influence of growth time ranging from 1 to 4 min on structural, optical and e...This paper examines the growth of ZnO thin films on glass substrate at 350 ℃ using an ultrasonic spray technique. We have investigated the influence of growth time ranging from 1 to 4 min on structural, optical and electrical properties of ZnO thin films. The as-grown films exhibit a hexagonal structure wurtzite and are （002） oriented. The maximum value of grain size G = 63.99 nm is attained for ZnO films grown at 2 min. The average transmittance is about 80%, thus the films are transparent in the visible region. The optical gap energy is found to increase from 3.26 to 3.37 eV with growth time increased from 1 to 2 min. The minimum value of electrical resistivity of the films is 0.13 Ω.cm obtained at 2 min. A systematic study on the influence of growth time on the properties of ZnO thin films deposited by ultrasonic spray at 350 ℃ has been reported.展开更多
Transparent conducting Co doped ZnO thin films have been fabricated by Ultrasonic spray. The thin films were deposited at three different substrate temperatures of 300, 350 and 400 ℃. The obtained films had a hexagon...Transparent conducting Co doped ZnO thin films have been fabricated by Ultrasonic spray. The thin films were deposited at three different substrate temperatures of 300, 350 and 400 ℃. The obtained films had a hexagonal wurtzite structure with a strong （002） preferred orientation. The maximum crystallite size value of the film deposited at 350 ℃ is 55.46 nm. Spectrophotometer （UV-vis） of a Co doped ZnO film deposited at 350 ℃ shows an average transmittance of about 90%. The band gap energy increased from 3.351 to 3.362 eV when the substrate temperature increased from 300 to 350 ℃. The electrical conductivity of the films deposited at 300, 350 and 400 ℃ were 7.424, 7.547 and 6.743 （Ω·cm）^-1 respectively. The maximum activation energy value of the films at 350 ℃ was 1.28 eV, indicating that the films exhibit a n-type semiconducting nature.展开更多
Transparent conductive Al doped ZnO thin films were deposited by ultrasonic spray technique.Conditions of preparation have been optimized to get good quality.A set of aluminum（Al） doped ZnO（between 0 and 5 wt%） th...Transparent conductive Al doped ZnO thin films were deposited by ultrasonic spray technique.Conditions of preparation have been optimized to get good quality.A set of aluminum（Al） doped ZnO（between 0 and 5 wt%） thin films were grown on glass substrate at 350℃.Nanocrystalline films with a hexagonal wurtzite structure show a strong（002） preferred orientation.The maximum value of grain size G = 32.05 nm is attained of Al doped ZnO film with 3 wt%.All the films have low absorbance in the visible region,thus the films are transparent in the visible region;the band gap energy increased from 3.10 to 3.26 eV when Al concentration increased from 0 to 3 wt%.The electrical conductivity of the films increased from 7.5 to 15.2（Ω·cm）^（-1）.So the best results are achieved in Al doped ZnO film with 3 wt%.展开更多
It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is o...It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowl- edge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during mea- surement. The ambient temperature over time is modeled based on the previous Train and Tmax data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.展开更多
This work is experimental investigation on the impact of rectangular baffles on the thermo-hydraulic performance of a solar thermal collector.The study was conducted under moderate weather conditions and six cases wer...This work is experimental investigation on the impact of rectangular baffles on the thermo-hydraulic performance of a solar thermal collector.The study was conducted under moderate weather conditions and six cases were studied,including 2M135,6M135,10M135,14M135,18M135,and a smooth plate case.The results showed that the number and placement of baffles plays a crucial role in improving heat transfer and the best cases in terms of thermal performance were cases V and IV,with maximum values of h=15.84 W/m2.k,and h=17.46 W/m2k.The study also found that the heat transfer was greatest at the beginning of the channel and decreased towards the end.The highest thermal efficiency was recorded in case 18M135 with a maximum value ofȠ=0.73.展开更多
文摘Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.
文摘This paper examines the growth of ZnO thin films on glass substrate at 350 ℃ using an ultrasonic spray technique. We have investigated the influence of growth time ranging from 1 to 4 min on structural, optical and electrical properties of ZnO thin films. The as-grown films exhibit a hexagonal structure wurtzite and are （002） oriented. The maximum value of grain size G = 63.99 nm is attained for ZnO films grown at 2 min. The average transmittance is about 80%, thus the films are transparent in the visible region. The optical gap energy is found to increase from 3.26 to 3.37 eV with growth time increased from 1 to 2 min. The minimum value of electrical resistivity of the films is 0.13 Ω.cm obtained at 2 min. A systematic study on the influence of growth time on the properties of ZnO thin films deposited by ultrasonic spray at 350 ℃ has been reported.
文摘Transparent conducting Co doped ZnO thin films have been fabricated by Ultrasonic spray. The thin films were deposited at three different substrate temperatures of 300, 350 and 400 ℃. The obtained films had a hexagonal wurtzite structure with a strong （002） preferred orientation. The maximum crystallite size value of the film deposited at 350 ℃ is 55.46 nm. Spectrophotometer （UV-vis） of a Co doped ZnO film deposited at 350 ℃ shows an average transmittance of about 90%. The band gap energy increased from 3.351 to 3.362 eV when the substrate temperature increased from 300 to 350 ℃. The electrical conductivity of the films deposited at 300, 350 and 400 ℃ were 7.424, 7.547 and 6.743 （Ω·cm）^-1 respectively. The maximum activation energy value of the films at 350 ℃ was 1.28 eV, indicating that the films exhibit a n-type semiconducting nature.
文摘Transparent conductive Al doped ZnO thin films were deposited by ultrasonic spray technique.Conditions of preparation have been optimized to get good quality.A set of aluminum（Al） doped ZnO（between 0 and 5 wt%） thin films were grown on glass substrate at 350℃.Nanocrystalline films with a hexagonal wurtzite structure show a strong（002） preferred orientation.The maximum value of grain size G = 32.05 nm is attained of Al doped ZnO film with 3 wt%.All the films have low absorbance in the visible region,thus the films are transparent in the visible region;the band gap energy increased from 3.10 to 3.26 eV when Al concentration increased from 0 to 3 wt%.The electrical conductivity of the films increased from 7.5 to 15.2（Ω·cm）^（-1）.So the best results are achieved in Al doped ZnO film with 3 wt%.
文摘It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowl- edge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during mea- surement. The ambient temperature over time is modeled based on the previous Train and Tmax data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.
文摘This work is experimental investigation on the impact of rectangular baffles on the thermo-hydraulic performance of a solar thermal collector.The study was conducted under moderate weather conditions and six cases were studied,including 2M135,6M135,10M135,14M135,18M135,and a smooth plate case.The results showed that the number and placement of baffles plays a crucial role in improving heat transfer and the best cases in terms of thermal performance were cases V and IV,with maximum values of h=15.84 W/m2.k,and h=17.46 W/m2k.The study also found that the heat transfer was greatest at the beginning of the channel and decreased towards the end.The highest thermal efficiency was recorded in case 18M135 with a maximum value ofȠ=0.73.
