在海洋资源勘测和环境监测活动中,常需要准确测量水下声速信息。利用TDC-GP22设计了一种低成本的小型化声速仪,针对飞行时间(Time of Flight,TOF)法测声速过程中存在的超声波衰减等问题,提出了一种基于首波脉冲宽度的可变阈值算法,根据...在海洋资源勘测和环境监测活动中,常需要准确测量水下声速信息。利用TDC-GP22设计了一种低成本的小型化声速仪,针对飞行时间(Time of Flight,TOF)法测声速过程中存在的超声波衰减等问题,提出了一种基于首波脉冲宽度的可变阈值算法,根据回波信号的首波脉冲宽度值动态调整检测阈值,提高了测量结果的稳定性。同时通过分析声速测量过程中的常见误差来源,在系统动态标定环节设计了一种基于RBF神经网络的温度补偿算法,校准了温度带来的换能器频率偏移以及声电延时等误差。在不同温盐条件下的声速测量结果表明该系统能以较低的成本获取高精度水下声速信息。展开更多
Objective To identify genes that involved in spermatogenesis. Methods In order to screen the testis-specific genes, testes cDNA samples from BALB/c mice of different postnatal days （days 4, 9, 18, 35, 54 and 6 months...Objective To identify genes that involved in spermatogenesis. Methods In order to screen the testis-specific genes, testes cDNA samples from BALB/c mice of different postnatal days （days 4, 9, 18, 35, 54 and 6 months） were performed with mouse whole genome Affymetrix chip. The characteristics of the selected gene were analyzed by various bioinformatic tools. The expression profile of the selected gene was identified by RT-PCR. Results By analyzing the hybridization signals, a gene with a differential expression in the developmental stages of testis was identified. This gene was designated as TSF22. The full length cDNA of 1 597 bp contained an open reading frame of 570 bp which encoded a putative protein of 190 amino acids and a molecular weight of 22.106 kD. RT-PCR analysis revealed that TSF22 mRNA was exclusively expressed in mice testis. Conclusions TSF22, functions as a testis-specific transcription factor, may play important roles during spermatogenesis.展开更多
文摘在海洋资源勘测和环境监测活动中,常需要准确测量水下声速信息。利用TDC-GP22设计了一种低成本的小型化声速仪,针对飞行时间(Time of Flight,TOF)法测声速过程中存在的超声波衰减等问题,提出了一种基于首波脉冲宽度的可变阈值算法,根据回波信号的首波脉冲宽度值动态调整检测阈值,提高了测量结果的稳定性。同时通过分析声速测量过程中的常见误差来源,在系统动态标定环节设计了一种基于RBF神经网络的温度补偿算法,校准了温度带来的换能器频率偏移以及声电延时等误差。在不同温盐条件下的声速测量结果表明该系统能以较低的成本获取高精度水下声速信息。
基金This study was supported by grants from Chinese Natural Science Funds(No.30471728,No.30500543)Natural Science Funds of Guangdong Province(No.04007303)
文摘Objective To identify genes that involved in spermatogenesis. Methods In order to screen the testis-specific genes, testes cDNA samples from BALB/c mice of different postnatal days （days 4, 9, 18, 35, 54 and 6 months） were performed with mouse whole genome Affymetrix chip. The characteristics of the selected gene were analyzed by various bioinformatic tools. The expression profile of the selected gene was identified by RT-PCR. Results By analyzing the hybridization signals, a gene with a differential expression in the developmental stages of testis was identified. This gene was designated as TSF22. The full length cDNA of 1 597 bp contained an open reading frame of 570 bp which encoded a putative protein of 190 amino acids and a molecular weight of 22.106 kD. RT-PCR analysis revealed that TSF22 mRNA was exclusively expressed in mice testis. Conclusions TSF22, functions as a testis-specific transcription factor, may play important roles during spermatogenesis.
