The North China Plain(NCP) has recently faced serious air quality problems as a result of enhanced gas pollutant emissions due to the process of urbanization and rapid economic growth.To explore regional air pollution...The North China Plain(NCP) has recently faced serious air quality problems as a result of enhanced gas pollutant emissions due to the process of urbanization and rapid economic growth.To explore regional air pollution in the NCP,measurements of surface ozone(O3),nitrogen oxides(NOx),and sulfur dioxide(SO2) were carried out from May to November 2013 at a rural site(Xianghe) between the twin megacities of Beijing and Tianjin.The highest hourly ozone average was close to 240 ppbv in May,followed by around 160 ppbv in June and July.High ozone episodes were more notable than in 2005 and were mainly associated with air parcels from the city cluster in the hinterland of the polluted NCP to the southwest of the site.For NOx,an important ozone precursor,the concentrations ranged from several ppbv to nearly 180 ppbv in the summer and over 400 ppbv in the fall.The occurrence of high NOx concentrations under calm conditions indicated that local emissions were dominant in Xianghe.The double-peak diurnal pattern found in NOxconcentrations and NO/NOx ratios was probably shaped by local emissions,photochemical removal,and dilution resulting from diurnal variations of surface wind speed and the boundary layer height.A pronounced SO2 daytime peak was noted and attributed to downward mixing from an SO2-rich layer above,while the SO2-polluted air mass transported from possible emission sources,which differed between the non-heating(September and October) and heating(November) periods,was thought to be responsible for night-time high concentrations.展开更多
The popularity of technology has allowed universities to make changes through their educational system in recent years. Some transitioned from face-to-face instruction to online instruction. The aim of this study is t...The popularity of technology has allowed universities to make changes through their educational system in recent years. Some transitioned from face-to-face instruction to online instruction. The aim of this study is to investigate the perceptions of both the instructors and the students as regards second language acquisition through online education at a rural university. The study was implemented in the context of teaching and learning English as a second language in an online education environment. The course material is based on The Net Languages Learning Platform, which is available at http：//ide.yok.gov.tr/, and the course level is general English pre-elementary. Both quantitative and qualitative methods were used in this study. For quantitative data collection, a questionnaire was employed to understand the reasons for low student attendance on online courses. For qualitative research method, observation was carried out, and interviews are designed as data collection techniques. Purposive selection was used for selection of the participants. The findings revealed that online education needs to be modified. The students are eager to improve their second language competencies; however, they do not want to waste their time on an easy course level.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.41305114 and 41175030)supported by Beijing Municipal Natural Science Foundation (Grant No.8121002)
文摘The North China Plain(NCP) has recently faced serious air quality problems as a result of enhanced gas pollutant emissions due to the process of urbanization and rapid economic growth.To explore regional air pollution in the NCP,measurements of surface ozone(O3),nitrogen oxides(NOx),and sulfur dioxide(SO2) were carried out from May to November 2013 at a rural site(Xianghe) between the twin megacities of Beijing and Tianjin.The highest hourly ozone average was close to 240 ppbv in May,followed by around 160 ppbv in June and July.High ozone episodes were more notable than in 2005 and were mainly associated with air parcels from the city cluster in the hinterland of the polluted NCP to the southwest of the site.For NOx,an important ozone precursor,the concentrations ranged from several ppbv to nearly 180 ppbv in the summer and over 400 ppbv in the fall.The occurrence of high NOx concentrations under calm conditions indicated that local emissions were dominant in Xianghe.The double-peak diurnal pattern found in NOxconcentrations and NO/NOx ratios was probably shaped by local emissions,photochemical removal,and dilution resulting from diurnal variations of surface wind speed and the boundary layer height.A pronounced SO2 daytime peak was noted and attributed to downward mixing from an SO2-rich layer above,while the SO2-polluted air mass transported from possible emission sources,which differed between the non-heating(September and October) and heating(November) periods,was thought to be responsible for night-time high concentrations.
文摘The popularity of technology has allowed universities to make changes through their educational system in recent years. Some transitioned from face-to-face instruction to online instruction. The aim of this study is to investigate the perceptions of both the instructors and the students as regards second language acquisition through online education at a rural university. The study was implemented in the context of teaching and learning English as a second language in an online education environment. The course material is based on The Net Languages Learning Platform, which is available at http：//ide.yok.gov.tr/, and the course level is general English pre-elementary. Both quantitative and qualitative methods were used in this study. For quantitative data collection, a questionnaire was employed to understand the reasons for low student attendance on online courses. For qualitative research method, observation was carried out, and interviews are designed as data collection techniques. Purposive selection was used for selection of the participants. The findings revealed that online education needs to be modified. The students are eager to improve their second language competencies; however, they do not want to waste their time on an easy course level.
