Based on the proposed partly equidifferent mapping and its specific Differential Amplitude and Pulse Position Modulation(DAPPM) demodulation, a modified FSO scheme for turbulent channel is designed and analyzed. The n...Based on the proposed partly equidifferent mapping and its specific Differential Amplitude and Pulse Position Modulation(DAPPM) demodulation, a modified FSO scheme for turbulent channel is designed and analyzed. The novel Low Density Parity Check(LDPC) coded 4×4 and 4×8 DAPPM Free-Space Optical communication(FSO) system is constructed. The Monte Carlo simulation results show approximately 2d B transmit power reduction against classical LDPC-DAPPM at the identical Bit-Error-Rate in strong turbulent channel. The proposed partly equidifferent mapping is compatible with other modulations, so it enables widespread adoption in other coded FSO systems.展开更多
The aim of this study was to determine the possible build up of heavy metals （Pb, Cu, Fe, Mn and Zn） in the Sakumo lagoon, a Ramsar site situated 3 km west of Tema, an industrial town in Ghana. To achieve this, surf...The aim of this study was to determine the possible build up of heavy metals （Pb, Cu, Fe, Mn and Zn） in the Sakumo lagoon, a Ramsar site situated 3 km west of Tema, an industrial town in Ghana. To achieve this, surface sediments were collected from three sections designated as south, centre and north of the lagoon. Sampling was done for a period of six months （September 2007 to February 2008） and concentrations of the heavy metals （Pb, Cu, Mn, Fe and Zn） in the sediments were determined using the atomic absorption spectrophotometer. The results were compared with the mean concentrations of these metals from a study carried out on the same lagoon in 2003. It was observed that concentrations of these heavy metals in the sediments showed a significant increase over the 2003 levels except for lead where a decrease was observed. The metals also showed spatially large variation from south to north. The spatial variations in concentrations indicate the different absorption capacities of the sediments in the lagoon, a phenomenon which shows that recent anthropogenic heavy metal pollution had occurred. Statistical analysis also showed significant correlation between Pb and Cu （0.968） at 0.01 confidence level and between Cu and Zn （0.869） at 0.05 confidence level.展开更多
基金supported by the National High-tech R&D Program (863 Program) 2013AA041003the Natural Science Foundation of China under Grants 51165033the Science and Technology Department of Jiangxi Province of China under grant 20151BBE50046,20142BBE50035 and 20151BAB207052
文摘Based on the proposed partly equidifferent mapping and its specific Differential Amplitude and Pulse Position Modulation(DAPPM) demodulation, a modified FSO scheme for turbulent channel is designed and analyzed. The novel Low Density Parity Check(LDPC) coded 4×4 and 4×8 DAPPM Free-Space Optical communication(FSO) system is constructed. The Monte Carlo simulation results show approximately 2d B transmit power reduction against classical LDPC-DAPPM at the identical Bit-Error-Rate in strong turbulent channel. The proposed partly equidifferent mapping is compatible with other modulations, so it enables widespread adoption in other coded FSO systems.
文摘The aim of this study was to determine the possible build up of heavy metals （Pb, Cu, Fe, Mn and Zn） in the Sakumo lagoon, a Ramsar site situated 3 km west of Tema, an industrial town in Ghana. To achieve this, surface sediments were collected from three sections designated as south, centre and north of the lagoon. Sampling was done for a period of six months （September 2007 to February 2008） and concentrations of the heavy metals （Pb, Cu, Mn, Fe and Zn） in the sediments were determined using the atomic absorption spectrophotometer. The results were compared with the mean concentrations of these metals from a study carried out on the same lagoon in 2003. It was observed that concentrations of these heavy metals in the sediments showed a significant increase over the 2003 levels except for lead where a decrease was observed. The metals also showed spatially large variation from south to north. The spatial variations in concentrations indicate the different absorption capacities of the sediments in the lagoon, a phenomenon which shows that recent anthropogenic heavy metal pollution had occurred. Statistical analysis also showed significant correlation between Pb and Cu （0.968） at 0.01 confidence level and between Cu and Zn （0.869） at 0.05 confidence level.
