In this paper,an improved error-rate sliding window decoder is proposed for spatially coupled low-density parity-check(SC-LDPC)codes.For the conventional sliding window decoder,the message retention mechanism causes u...In this paper,an improved error-rate sliding window decoder is proposed for spatially coupled low-density parity-check(SC-LDPC)codes.For the conventional sliding window decoder,the message retention mechanism causes unreliable messages along the edges of belief propagation(BP)decoding in the current window to be kept for subsequent window decoding.To improve the reliability of the retained messages during the window transition,a reliable termination method is embedded,where the retained messages undergo more reliable parity checks.Additionally,decoding failure is unavoidable and even causes error propagation when the number of errors exceeds the error-correcting capability of the window.To mitigate this problem,a channel value reuse mechanism is designed,where the received channel values are utilized to reinitialize the window.Furthermore,considering the complexity and performance of decoding,a feasible sliding optimized window decoding(SOWD)scheme is introduced.Finally,simulation results confirm the superior performance of the proposed SOWD scheme in both the waterfall and error floor regions.This work has great potential in the applications of wireless optical communication and fiber optic communication.展开更多
This paper revisits the characteristics of windowing techniques with various window functions involved,and successively investigates spectral leakage mitigation utilizing the Welch method.The discrete Fourier transfor...This paper revisits the characteristics of windowing techniques with various window functions involved,and successively investigates spectral leakage mitigation utilizing the Welch method.The discrete Fourier transform(DFT)is ubiquitous in digital signal processing(DSP)for the spectrum analysis and can be efciently realized by the fast Fourier transform(FFT).The sampling signal will result in distortion and thus may cause unpredictable spectral leakage in discrete spectrum when the DFT is employed.Windowing is implemented by multiplying the input signal with a window function and windowing amplitude modulates the input signal so that the spectral leakage is evened out.Therefore,windowing processing reduces the amplitude of the samples at the beginning and end of the window.In addition to selecting appropriate window functions,a pretreatment method,such as the Welch method,is effective to mitigate the spectral leakage.Due to the noise caused by imperfect,nite data,the noise reduction from Welch’s method is a desired treatment.The nonparametric Welch method is an improvement on the periodogram spectrum estimation method where the signal-to-noise ratio(SNR)is high and mitigates noise in the estimated power spectra in exchange for frequency resolution reduction.The periodogram technique based on Welch method is capable of providing good resolution if data length samples are appropriately selected.The design of nite impulse response(FIR)digital lter using the window technique is rstly addressed.The inuence of various window functions on the Fourier transform spectrum of the signals is discussed.Comparison on spectral resolution based on the traditional power spectrum estimation and various window-function-based Welch power spectrum estimations is presented.展开更多
Infrared window in hypersonic missile usually suffers complex aerodynamic force/heat during high-speed flight.A finite element method was adopted to simulate the thermal and stress response of microscale functional fi...Infrared window in hypersonic missile usually suffers complex aerodynamic force/heat during high-speed flight.A finite element method was adopted to simulate the thermal and stress response of microscale functional film for infrared window under different aerodynamic heats/forces conditions.Temperature and stress distribution were obtained with different heat fluxes.There is almost constant stress distribution along the film thickness except a sudden decrease near the substrate.The maximum stresses are located at the points which are 0.3 mm away from the edges.Different film materials result in different stress values.The temperature and stress in ZrN are larger than those in Y2O3.Besides the numerical simulation,an oxygen propane flame jet impingement test was performed to investigate thermal shock failure of the infrared window.Some place of the window surface has spots damage and some place has line crack damage after thermal shock.展开更多
[Objective] This study aimed to establish a new method for preparing paraffin sections of cattle eyebal s. [Method] The conventional method was used to prepare paraffin sections for cattle eyebal s in the control and ...[Objective] This study aimed to establish a new method for preparing paraffin sections of cattle eyebal s. [Method] The conventional method was used to prepare paraffin sections for cattle eyebal s in the control and a new method termed＆quot;opening a window on cornea and refixation＆quot; was used to prepare paraffin sections for cattle eyebal s in the treatment group. [Result] After the prepared specimens in the treatment group were fixed, it could be macroscopical y observed that retina and choroid were closely connected, with detachment occurring at a smal portion be-tween the two. According to the paraffin sections, it was microscopical y observed that the continuity of trabecular meshwork was intact, as wel as the continuity be-tween different layers of eyebal wal , without detachment between them, no retinal detachment, no shrinkage of each layer of tissue cells. [Conclusion] This study pro-vides a foundation for the basic research and pathological study of eyebal s.展开更多
基金supported by the National Natural Science Foundation of China (No.62275193)。
文摘In this paper,an improved error-rate sliding window decoder is proposed for spatially coupled low-density parity-check(SC-LDPC)codes.For the conventional sliding window decoder,the message retention mechanism causes unreliable messages along the edges of belief propagation(BP)decoding in the current window to be kept for subsequent window decoding.To improve the reliability of the retained messages during the window transition,a reliable termination method is embedded,where the retained messages undergo more reliable parity checks.Additionally,decoding failure is unavoidable and even causes error propagation when the number of errors exceeds the error-correcting capability of the window.To mitigate this problem,a channel value reuse mechanism is designed,where the received channel values are utilized to reinitialize the window.Furthermore,considering the complexity and performance of decoding,a feasible sliding optimized window decoding(SOWD)scheme is introduced.Finally,simulation results confirm the superior performance of the proposed SOWD scheme in both the waterfall and error floor regions.This work has great potential in the applications of wireless optical communication and fiber optic communication.
基金supported by the Ministry of Science and Technology,Taiwan[Grant Numbers MOST 104-2221-E-019-026-MY2 and MOST 108-2221-E019-013].
文摘This paper revisits the characteristics of windowing techniques with various window functions involved,and successively investigates spectral leakage mitigation utilizing the Welch method.The discrete Fourier transform(DFT)is ubiquitous in digital signal processing(DSP)for the spectrum analysis and can be efciently realized by the fast Fourier transform(FFT).The sampling signal will result in distortion and thus may cause unpredictable spectral leakage in discrete spectrum when the DFT is employed.Windowing is implemented by multiplying the input signal with a window function and windowing amplitude modulates the input signal so that the spectral leakage is evened out.Therefore,windowing processing reduces the amplitude of the samples at the beginning and end of the window.In addition to selecting appropriate window functions,a pretreatment method,such as the Welch method,is effective to mitigate the spectral leakage.Due to the noise caused by imperfect,nite data,the noise reduction from Welch’s method is a desired treatment.The nonparametric Welch method is an improvement on the periodogram spectrum estimation method where the signal-to-noise ratio(SNR)is high and mitigates noise in the estimated power spectra in exchange for frequency resolution reduction.The periodogram technique based on Welch method is capable of providing good resolution if data length samples are appropriately selected.The design of nite impulse response(FIR)digital lter using the window technique is rstly addressed.The inuence of various window functions on the Fourier transform spectrum of the signals is discussed.Comparison on spectral resolution based on the traditional power spectrum estimation and various window-function-based Welch power spectrum estimations is presented.
基金Projects (51222205,51372053) supported by the National Natural Science Foundation of ChinaProject (JC201305) supported by Heilongjiang Provincial Science Fund for Distinguished Young Scholars,ChinaProject (20112302110036) supported by Ph.D. Programs Foundation of Ministry of Education of China
文摘Infrared window in hypersonic missile usually suffers complex aerodynamic force/heat during high-speed flight.A finite element method was adopted to simulate the thermal and stress response of microscale functional film for infrared window under different aerodynamic heats/forces conditions.Temperature and stress distribution were obtained with different heat fluxes.There is almost constant stress distribution along the film thickness except a sudden decrease near the substrate.The maximum stresses are located at the points which are 0.3 mm away from the edges.Different film materials result in different stress values.The temperature and stress in ZrN are larger than those in Y2O3.Besides the numerical simulation,an oxygen propane flame jet impingement test was performed to investigate thermal shock failure of the infrared window.Some place of the window surface has spots damage and some place has line crack damage after thermal shock.
基金Supported by China Agriculture Research System(CARS-38)~~
文摘[Objective] This study aimed to establish a new method for preparing paraffin sections of cattle eyebal s. [Method] The conventional method was used to prepare paraffin sections for cattle eyebal s in the control and a new method termed＆quot;opening a window on cornea and refixation＆quot; was used to prepare paraffin sections for cattle eyebal s in the treatment group. [Result] After the prepared specimens in the treatment group were fixed, it could be macroscopical y observed that retina and choroid were closely connected, with detachment occurring at a smal portion be-tween the two. According to the paraffin sections, it was microscopical y observed that the continuity of trabecular meshwork was intact, as wel as the continuity be-tween different layers of eyebal wal , without detachment between them, no retinal detachment, no shrinkage of each layer of tissue cells. [Conclusion] This study pro-vides a foundation for the basic research and pathological study of eyebal s.
