A scheme to design a simultaneous multichannel receiver is proposed to process multichannel signals in parallel, which is achieved by exploiting the attractive characteristics of a fast filter bank（ FFB）, such as ca...A scheme to design a simultaneous multichannel receiver is proposed to process multichannel signals in parallel, which is achieved by exploiting the attractive characteristics of a fast filter bank（ FFB）, such as cascaded structure, high frequency selectivity and lowcomputational complexity. Based on the minimization of the objective function, quantified in terms of the total number of multiplications required, subject to prescribed allowable ripples in the passband and stopband, the impulse response coefficients of the prototype filter in each stage are obtained to meet the requirements of the overall specifications for each channel at the receiver side. Simulations and experimental results on the frequency modulation（ FM） broadcast mutlichannel signal receiving system with the FM range from88 to 108 MHz, built upon the proposed FFB structure, are performed to verify its performance. Those results indicate that the proposed scheme is efficient in FM audio indexing applications and has a lower computational complexity, which is approximately 66. 4% of the weighted overlap and add（ WOLA） filter banks based solution.展开更多
After being compressed to different plastic deformation stages, the salt rock samples with lateral stress damage of 0.2, 0.3, 0.4, and 0.5 were selected. Ultrasonic technology was used to monitor the wave velocity var...After being compressed to different plastic deformation stages, the salt rock samples with lateral stress damage of 0.2, 0.3, 0.4, and 0.5 were selected. Ultrasonic technology was used to monitor the wave velocity variation law of stress-dam-aged salt rock during the self-recovery experiment under different temperatures to analyze the influence of initial stress damage and temperature during the self-recovery of salt rock. The experiment shows that the change of salt rock axial wave velocity is smaller than that of lateral wave velocity. The sample ultrasonic velocity is positively correlated with the time of self-recovery, and the damage had been recovered to a certain extent. In the first 200 hours of self-recovery stage, the salt rock lateral damage recovers fast, and then the damage remains almost unchanged. The value of lateral stable damage is positively correlated with the value of lateral initial stress damage. With the increase of temperature, the recovery of lateral damage speeds up and the value of stable damage decreases; the axial damage of salt rock almost remains unchanged during the self-recovery experiment.展开更多
Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) tec...Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.展开更多
Orthogonal frequency division multiplexing （OFDM） is a special form of multi-carrier transmission that uses the policy of divide and rule. In this scheme, a large number of orthogonal, overlapping, narrow band sub-c...Orthogonal frequency division multiplexing （OFDM） is a special form of multi-carrier transmission that uses the policy of divide and rule. In this scheme, a large number of orthogonal, overlapping, narrow band sub-channels （subcarriers） are transmitted in parallel and divide the available transmission bandwidth. This techniqueis originally based on the Fast Fourier Transform of the information data. In order to improve the performance of the OFDM and overcome some limitations, an alternative OFDM approach based on the Wavelet Transform is proposed. In this paper, we study the performance of such systems in additive white Gaussian channel （AWGN）. MATLAB simulations are realized and performance comparisons are presented.展开更多
The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks ...The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks between different apertures.In view of this,a new coding scheme using staggering repetition interval was proposed.The transmitting signals were constructed by repeating the two(or more) modulated codes using staggering repetition interval,and then allocated to and transmitted simultaneously among different apertures.The decoding process was based on the subsection-matched filter under the assistance of different matched filters for different apertures.At last the outputs of subsection-matched filtering were added together.Staggering changed the positions of cross-correlation(CC) peaks from coinciding,which resulted in an effective reduction of CC.Our theoretical analysis and simulations showed that,the coding scheme can be used to reduce cross-talk,and a good cross-talk reduction will be achieved if the staggering delay is kept in an appropriate range.展开更多
基金The National Natural Science Foundation of China(No.61201173,61271058,61401094)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20110092110008)+1 种基金the Natural Science Foundation of Jiangsu Province(No.SBK201140040,BK2011060,BK20140645)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China
文摘A scheme to design a simultaneous multichannel receiver is proposed to process multichannel signals in parallel, which is achieved by exploiting the attractive characteristics of a fast filter bank（ FFB）, such as cascaded structure, high frequency selectivity and lowcomputational complexity. Based on the minimization of the objective function, quantified in terms of the total number of multiplications required, subject to prescribed allowable ripples in the passband and stopband, the impulse response coefficients of the prototype filter in each stage are obtained to meet the requirements of the overall specifications for each channel at the receiver side. Simulations and experimental results on the frequency modulation（ FM） broadcast mutlichannel signal receiving system with the FM range from88 to 108 MHz, built upon the proposed FFB structure, are performed to verify its performance. Those results indicate that the proposed scheme is efficient in FM audio indexing applications and has a lower computational complexity, which is approximately 66. 4% of the weighted overlap and add（ WOLA） filter banks based solution.
基金Supported by the National Basic Research Program of China （973 Program） （2009CB724606） the Science Foundation for Excellent Youth Scholars of Ministry of Education of China （20090191110001） the National Natural Science Foundation of China （50674108）
文摘After being compressed to different plastic deformation stages, the salt rock samples with lateral stress damage of 0.2, 0.3, 0.4, and 0.5 were selected. Ultrasonic technology was used to monitor the wave velocity variation law of stress-dam-aged salt rock during the self-recovery experiment under different temperatures to analyze the influence of initial stress damage and temperature during the self-recovery of salt rock. The experiment shows that the change of salt rock axial wave velocity is smaller than that of lateral wave velocity. The sample ultrasonic velocity is positively correlated with the time of self-recovery, and the damage had been recovered to a certain extent. In the first 200 hours of self-recovery stage, the salt rock lateral damage recovers fast, and then the damage remains almost unchanged. The value of lateral stable damage is positively correlated with the value of lateral initial stress damage. With the increase of temperature, the recovery of lateral damage speeds up and the value of stable damage decreases; the axial damage of salt rock almost remains unchanged during the self-recovery experiment.
基金Founded by the National Natural Science Foundation of China (No.60502005).
文摘Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.
文摘Orthogonal frequency division multiplexing （OFDM） is a special form of multi-carrier transmission that uses the policy of divide and rule. In this scheme, a large number of orthogonal, overlapping, narrow band sub-channels （subcarriers） are transmitted in parallel and divide the available transmission bandwidth. This techniqueis originally based on the Fast Fourier Transform of the information data. In order to improve the performance of the OFDM and overcome some limitations, an alternative OFDM approach based on the Wavelet Transform is proposed. In this paper, we study the performance of such systems in additive white Gaussian channel （AWGN）. MATLAB simulations are realized and performance comparisons are presented.
基金Project (Nos.60772147 and 60871060) supported by the National Natural Science Foundation of China
文摘The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks between different apertures.In view of this,a new coding scheme using staggering repetition interval was proposed.The transmitting signals were constructed by repeating the two(or more) modulated codes using staggering repetition interval,and then allocated to and transmitted simultaneously among different apertures.The decoding process was based on the subsection-matched filter under the assistance of different matched filters for different apertures.At last the outputs of subsection-matched filtering were added together.Staggering changed the positions of cross-correlation(CC) peaks from coinciding,which resulted in an effective reduction of CC.Our theoretical analysis and simulations showed that,the coding scheme can be used to reduce cross-talk,and a good cross-talk reduction will be achieved if the staggering delay is kept in an appropriate range.
