Underwater acoustic communication based on Pattern Tune Delay Shift Coding （PDS） communication scheme is studied. The time delay shift values of the pattern are used to encode the digital information in the PDS sche...Underwater acoustic communication based on Pattern Tune Delay Shift Coding （PDS） communication scheme is studied. The time delay shift values of the pattern are used to encode the digital information in the PDS scheme, which belongs to the Pulse Position Modulation （PPM）. The duty cycle of the PDS scheme is small, so it can economize the power for communication. By use of different patterns for code division and different frequencies for channel division, the communication system is capable of mitigating the inter-symbol interference （ISI） caused by the muhipath channel. The data rate of communication is 1000 bits/s at 8 kHz bandwidth. The receiver separates the channels by means of bandpass filters, and performs decoding by 4 copy-correlators to estimate the time delay shift value. Based on the theoretical analysis and numerical simulations, the PDS scheme is shown to be a robust and effective approach for underwater acoustic communication.展开更多
Pattern Time Delay Shift Coding (PDS) scheme is robust for underwater acoustic communication. The digital information are encoded in the time delay shift values of the Pattern, so the PDS scheme belongs to the Pulse P...Pattern Time Delay Shift Coding (PDS) scheme is robust for underwater acoustic communication. The digital information are encoded in the time delay shift values of the Pattern, so the PDS scheme belongs to the Pulse Position Modulation (PPM). Several Patterns are selected for code division that the communication system could have a high ability to mitigate the inter-symbol interference (ISI) caused by multipath channel. Four communication channels work on the same time divided by different frequency, which lead to 1000bits/s of the data rate of communication. The simulation experiments show that the PDS system could adapt to many underwater acoustic channels for high data rate and high reliability.展开更多
Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields we...Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.展开更多
The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process i...The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process is out of statistical control and there are assignable causes for process variation that should be investigated. This paper proposes an artificial neural network algorithm to identify the three basic control chart patterns;natural, shift, and trend. This identification is in addition to the traditional statistical detection of runs in data, since runs are one of the out of control situations. It is assumed that a process starts as a natural pattern and then may undergo only one out of control pattern at a time. The performance of the proposed algorithm was evaluated by measuring the probability of success in identifying the three basic patterns accurately, and comparing these results with previous research work. The comparison showed that the proposed algorithm realized better identification than others.展开更多
Pattern时延差(PDS:Pattern time Delay Shift)编码通信体制具有很好的抗多途干扰能力,但传输过程中仍存在一定的误码。为提高该体制的抗噪声能力,将网格编码调制(TCM:Trellis-Coded Modulation)技术与PDS体制结合使用,对信息进行网格...Pattern时延差(PDS:Pattern time Delay Shift)编码通信体制具有很好的抗多途干扰能力,但传输过程中仍存在一定的误码。为提高该体制的抗噪声能力,将网格编码调制(TCM:Trellis-Coded Modulation)技术与PDS体制结合使用,对信息进行网格编码调制和维特比软判决译码。实验结果证明,该方案抗噪声效果显著,可使PDS体制的抗噪声性能提高3 dB左右。展开更多
研究了Pattern时延差编码(Pattern Time Delay Shift Coding,PTDS)水声通信的差分解码技术。在移动水声通信中,多普勒频偏会对信号产生时间上的压缩或展宽。差分解码通过测量相邻Pattern的时间差进行时延估计完成译码,克服了多普勒频偏...研究了Pattern时延差编码(Pattern Time Delay Shift Coding,PTDS)水声通信的差分解码技术。在移动水声通信中,多普勒频偏会对信号产生时间上的压缩或展宽。差分解码通过测量相邻Pattern的时间差进行时延估计完成译码,克服了多普勒频偏在时间上的累加效应,具有更强的抵抗多普勒能力,为移动水声通信技术的研究打下了基础。仿真实验证明所提出的解码方案简单易行、性能优良。展开更多
针对传统Pattern时延差(Pattern Time Delay Shift,PDS)编码水声通信速率较低的问题,在传统PDS水声通信基础上,提出基于分频带的高速PDS通信方案。借鉴无线电中多载波通信思想,将可用水声通信频带进行分割,多个子频带上同步传输PDS信号...针对传统Pattern时延差(Pattern Time Delay Shift,PDS)编码水声通信速率较低的问题,在传统PDS水声通信基础上,提出基于分频带的高速PDS通信方案。借鉴无线电中多载波通信思想,将可用水声通信频带进行分割,多个子频带上同步传输PDS信号,结合被动时间反转镜信道估计技术,达到提高水声通信速率的目的。试验结果表明,在强多途水声信道环境下,实现了远程低误码率传输,不仅能够有效抑制强多途干扰,还能够提升水声通信速率。展开更多
文摘Underwater acoustic communication based on Pattern Tune Delay Shift Coding （PDS） communication scheme is studied. The time delay shift values of the pattern are used to encode the digital information in the PDS scheme, which belongs to the Pulse Position Modulation （PPM）. The duty cycle of the PDS scheme is small, so it can economize the power for communication. By use of different patterns for code division and different frequencies for channel division, the communication system is capable of mitigating the inter-symbol interference （ISI） caused by the muhipath channel. The data rate of communication is 1000 bits/s at 8 kHz bandwidth. The receiver separates the channels by means of bandpass filters, and performs decoding by 4 copy-correlators to estimate the time delay shift value. Based on the theoretical analysis and numerical simulations, the PDS scheme is shown to be a robust and effective approach for underwater acoustic communication.
文摘Pattern Time Delay Shift Coding (PDS) scheme is robust for underwater acoustic communication. The digital information are encoded in the time delay shift values of the Pattern, so the PDS scheme belongs to the Pulse Position Modulation (PPM). Several Patterns are selected for code division that the communication system could have a high ability to mitigate the inter-symbol interference (ISI) caused by multipath channel. Four communication channels work on the same time divided by different frequency, which lead to 1000bits/s of the data rate of communication. The simulation experiments show that the PDS system could adapt to many underwater acoustic channels for high data rate and high reliability.
文摘Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.
文摘The identification of control chart patterns is very important in statistical process control. Control chart patterns are categorized as natural and unnatural. The presence of unnatural patterns means that a process is out of statistical control and there are assignable causes for process variation that should be investigated. This paper proposes an artificial neural network algorithm to identify the three basic control chart patterns;natural, shift, and trend. This identification is in addition to the traditional statistical detection of runs in data, since runs are one of the out of control situations. It is assumed that a process starts as a natural pattern and then may undergo only one out of control pattern at a time. The performance of the proposed algorithm was evaluated by measuring the probability of success in identifying the three basic patterns accurately, and comparing these results with previous research work. The comparison showed that the proposed algorithm realized better identification than others.
文摘研究了Pattern时延差编码(Pattern Time Delay Shift Coding,PTDS)水声通信的差分解码技术。在移动水声通信中,多普勒频偏会对信号产生时间上的压缩或展宽。差分解码通过测量相邻Pattern的时间差进行时延估计完成译码,克服了多普勒频偏在时间上的累加效应,具有更强的抵抗多普勒能力,为移动水声通信技术的研究打下了基础。仿真实验证明所提出的解码方案简单易行、性能优良。
文摘针对传统Pattern时延差(Pattern Time Delay Shift,PDS)编码水声通信速率较低的问题,在传统PDS水声通信基础上,提出基于分频带的高速PDS通信方案。借鉴无线电中多载波通信思想,将可用水声通信频带进行分割,多个子频带上同步传输PDS信号,结合被动时间反转镜信道估计技术,达到提高水声通信速率的目的。试验结果表明,在强多途水声信道环境下,实现了远程低误码率传输,不仅能够有效抑制强多途干扰,还能够提升水声通信速率。
