在可见光通信领域,通过波分复用技术可以增加信道个数,从而提高系统通信容量.然而发光二极管(LED)的辐射光谱具有一定线宽,当信道个数增加,信道间隔将变小,尽管有滤光片的通道选择,但LED的辐射光谱会出现重叠从而产生信道串扰.本文基于...在可见光通信领域,通过波分复用技术可以增加信道个数,从而提高系统通信容量.然而发光二极管(LED)的辐射光谱具有一定线宽,当信道个数增加,信道间隔将变小,尽管有滤光片的通道选择,但LED的辐射光谱会出现重叠从而产生信道串扰.本文基于LED光谱重叠现象分析了多光谱波分复用可见光通信系统的信道串扰问题.首先结合LED的物理机制和实际LED的光谱形状对其光谱进行建模;然后根据光谱重叠现象和可见光通信信道推导出信道串扰公式;最后利用不同中心波长的LED在两通道可见光通信系统中验证了信道串扰公式的正确性.仿真和实验结果表明,当两信道的信道间隔大于28 nm时,两信道之间的信道串扰不超过-13.6 d B.对多光谱波分复用可见光通信系统的信道串扰分析对未来可见光通信增加信道数量有一定指导作用.展开更多
Antibiotic growth promoters that have been historically employed to control pathogens and increase the rate of animal development for human consumption are currently banned in many countries. Probiotics have been prop...Antibiotic growth promoters that have been historically employed to control pathogens and increase the rate of animal development for human consumption are currently banned in many countries. Probiotics have been proposed as an alternative to control pathogenic bacteria. Traditional culture methods typically used to monitor probiotic effects on pathogens possess significant limitations such as a lack in sensitivity to detect fastidious and non-culturable bacteria, and are both time consuming and costly. Here, we tested next generation pyrosequencing technology as a streamline and economical method to monitor the effects of a probiotic on microbial communities in juvenile poultry (Gallus gallus domesticus) after exposure to several microbiological challenges and litter conditions. Seven days and repeated again at 39 days following hatching, chicks were challenged with either Salmonella enterica serovar Enteritidis, Campylobacter jejuni, or no bacteria in the presence of, or without a probiotic (i.e., Bacillus subtilis) added to the feed. Three days following each of two challenges (i.e., days 10 and 42, respectively) the microbiome distributions of the poultry caecum were characterized based on 16S rDNA analysis. Generated PCR products were analyzed by automated identification of the samples after pooling, multiplexing and sequencing. A bioinformatics pipeline was then employed to identify microbial distributions at the phylum and genus level for the treatments. In conclusion, our results demonstrated that pyrosequencing technology is a rapid, efficient and cost-effective method to monitor the effects of probiotics on the microbiome of poultry propagated in an agricultural setting.展开更多
In this paper, the design of signal constellations parameters is studied for Differential Unitary Space-Time Modulation (DUSTM) based on the design criterion of maximizing the diversity product. Further, noninteger se...In this paper, the design of signal constellations parameters is studied for Differential Unitary Space-Time Modulation (DUSTM) based on the design criterion of maximizing the diversity product. Further, noninteger searching method for the signal constellation parameters design is proposed in order to get better codes. Experimental results show that under the different Doppler spread and data transmission rate, the proposed design performs better than the previous design using integer parameters in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system over frequency-selective fading channels.展开更多
文摘在可见光通信领域,通过波分复用技术可以增加信道个数,从而提高系统通信容量.然而发光二极管(LED)的辐射光谱具有一定线宽,当信道个数增加,信道间隔将变小,尽管有滤光片的通道选择,但LED的辐射光谱会出现重叠从而产生信道串扰.本文基于LED光谱重叠现象分析了多光谱波分复用可见光通信系统的信道串扰问题.首先结合LED的物理机制和实际LED的光谱形状对其光谱进行建模;然后根据光谱重叠现象和可见光通信信道推导出信道串扰公式;最后利用不同中心波长的LED在两通道可见光通信系统中验证了信道串扰公式的正确性.仿真和实验结果表明,当两信道的信道间隔大于28 nm时,两信道之间的信道串扰不超过-13.6 d B.对多光谱波分复用可见光通信系统的信道串扰分析对未来可见光通信增加信道数量有一定指导作用.
文摘Antibiotic growth promoters that have been historically employed to control pathogens and increase the rate of animal development for human consumption are currently banned in many countries. Probiotics have been proposed as an alternative to control pathogenic bacteria. Traditional culture methods typically used to monitor probiotic effects on pathogens possess significant limitations such as a lack in sensitivity to detect fastidious and non-culturable bacteria, and are both time consuming and costly. Here, we tested next generation pyrosequencing technology as a streamline and economical method to monitor the effects of a probiotic on microbial communities in juvenile poultry (Gallus gallus domesticus) after exposure to several microbiological challenges and litter conditions. Seven days and repeated again at 39 days following hatching, chicks were challenged with either Salmonella enterica serovar Enteritidis, Campylobacter jejuni, or no bacteria in the presence of, or without a probiotic (i.e., Bacillus subtilis) added to the feed. Three days following each of two challenges (i.e., days 10 and 42, respectively) the microbiome distributions of the poultry caecum were characterized based on 16S rDNA analysis. Generated PCR products were analyzed by automated identification of the samples after pooling, multiplexing and sequencing. A bioinformatics pipeline was then employed to identify microbial distributions at the phylum and genus level for the treatments. In conclusion, our results demonstrated that pyrosequencing technology is a rapid, efficient and cost-effective method to monitor the effects of probiotics on the microbiome of poultry propagated in an agricultural setting.
基金Supported by the National Natural Science Foundation of China (No.60772062)the National Basic Research Pro-gram of China (No.2007CB310607)the Natural Science Research Fund of Jiangsu University (No. 05 KJB 510090)
文摘In this paper, the design of signal constellations parameters is studied for Differential Unitary Space-Time Modulation (DUSTM) based on the design criterion of maximizing the diversity product. Further, noninteger searching method for the signal constellation parameters design is proposed in order to get better codes. Experimental results show that under the different Doppler spread and data transmission rate, the proposed design performs better than the previous design using integer parameters in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system over frequency-selective fading channels.
