This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding type...This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding types on communication performance.The study investigates the impact of on-off keying(OOK)and 2-pulse-position modulation(2-PPM)on the bit error rate(BER)in single-channel intensity and polarization multiplexing.Furthermore,it compares the error correction performance of low-density parity check(LDPC)and Reed-Solomon(RS)codes across different error correction coding types.The effects of unscattered photon ratio and depolarization ratio on BER are also verified.Finally,a UWOC system based on SPD is constructed,achieving 14.58 Mbps with polarization OOK multiplexing modulation and 4.37 Mbps with polarization 2-PPM multiplexing modulation using LDPC code error correction.展开更多
A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simul...A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.展开更多
In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper,...In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper, the complementary error function is proposed instead of the cubic spline function as the transition zone function, due to the availability of analytical expression of its derivatives and the nonnegativity fact. It is shown that with the use of the complementary error function, transition zones for all refractive types work correctly.展开更多
In this paper, we present two new algorithms in residue number systems for scaling and error correction. The first algorithm is the Cyclic Property of Residue-Digit Difference (CPRDD). It is used to speed up the resid...In this paper, we present two new algorithms in residue number systems for scaling and error correction. The first algorithm is the Cyclic Property of Residue-Digit Difference (CPRDD). It is used to speed up the residue multiple error correction due to its parallel processes. The second is called the Target Race Distance (TRD). It is used to speed up residue scaling. Both of these two algorithms are used without the need for Mixed Radix Conversion (MRC) or Chinese Residue Theorem (CRT) techniques, which are time consuming and require hardware complexity. Furthermore, the residue scaling can be performed in parallel for any combination of moduli set members without using lookup tables.展开更多
Through the analysis for the process of Walsh modulation and demodula tion,the adaptive error-limiting method suitable for the Walsh code shutting multiplex ing in the mine monitor system is advanced in this article. ...Through the analysis for the process of Walsh modulation and demodula tion,the adaptive error-limiting method suitable for the Walsh code shutting multiplex ing in the mine monitor system is advanced in this article. It is proved by theoretical analysis and circuit experiments that this method is easy to carry out and can not only improve the quality of information transmission but also meet the requirement of the system patrol test time without the increasement of system investment.展开更多
A dual double interlocked storage cell(DICE)interleaving layout static random-access memory(SRAM)is designed and manufactured based on 65 nm bulk complementary metal oxide semiconductor technology.The single event ups...A dual double interlocked storage cell(DICE)interleaving layout static random-access memory(SRAM)is designed and manufactured based on 65 nm bulk complementary metal oxide semiconductor technology.The single event upset(SEU)cross sections of this memory are obtained via heavy ion irradiation with a linear energy transfer(LET)value ranging from 1.7 to 83.4 MeV/(mg/cm^(2)).Experimental results show that the upset threshold(LETth)of a 4 KB block is approximately 6 MeV/(mg/cm^(2)),which is much better than that of a standard unhardened SRAM with an identical technology node.A 1 KB block has a higher LETth of 25 MeV/(mg/cm^(2))owing to the use of the error detection and correction(EDAC)code.For a Ta ion irradiation test with the highest LET value(83.4 MeV/(mg/cm^(2))),the benefit of the EDAC code is reduced significantly because the multi-bit upset proportion in the SEU is increased remarkably.Compared with normal incident ions,the memory exhibits a higher SEU sensitivity in the tilt angle irradiation test.Moreover,the SEU cross section indicates a significant dependence on the data pattern.When comprehensively considering HSPICE simulation results and the sensitive area distributions of the DICE cell,it is shown that the data pattern dependence is primarily associated with the arrangement of sensitive transistor pairs in the layout.Finally,some suggestions are provided to further improve the radiation resistance of the memory.By implementing a particular design at the layout level,the SEU tolerance of the memory is improved significantly at a low area cost.Therefore,the designed 65 nm SRAM is suitable for electronic systems operating in serious radiation environments.展开更多
According to the data from Investigation Report of Land Use Change in China,The Land Resources Communique of China and Chronicle of Statistical Data for Five Decades of New China issued from Ministry of Land Resources...According to the data from Investigation Report of Land Use Change in China,The Land Resources Communique of China and Chronicle of Statistical Data for Five Decades of New China issued from Ministry of Land Resources,we select two indices:change of farmland quantity and policy of farmland protection.According to econometric theory,by using Eviewes 5.1 software,co-integration analysis,Granger causality test,impulse response and other analysis methods,we analyze the relationship between change of farmland quantity and policy of farmland protection in China since the reform and opening-up.The results show that there is long-term balanced relationship between change of farmland quantity and policy of farmland protection,and there is a certain mechanism restricting motion of variables between the two so as to make the two deviate from each other little and step towards balance in the long run;there is unilateral causality relationship between farmland change and policy of farmland protection,namely that the farmland change is the Granger cause of policy of farmland protection,while policy of farmland protection is not the Granger cause of farmland change;impulse response and variance decomposition indicate that farmland change plays the role of promoting policy of farmland protection continuously,and the role is strengthened along with prolonged lag period;the policy of farmland protection has strong inertia,because it is impacted by the former level of itself,and the policy of farmland protection plays insignificant role in promoting farmland quantity.Consequently,the important approach of solving problem of rapid decrease of farmland is to formulate long-term strategy,strengthen theoretical research of farmland protection and reinforce degree of formulation,implementation and surveillance of farmland protection policy.展开更多
基金supported in part by the National Natural Science Foundation of China(Nos.62071441 and 61701464)in part by the Fundamental Research Funds for the Central Universities(No.202151006).
文摘This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding types on communication performance.The study investigates the impact of on-off keying(OOK)and 2-pulse-position modulation(2-PPM)on the bit error rate(BER)in single-channel intensity and polarization multiplexing.Furthermore,it compares the error correction performance of low-density parity check(LDPC)and Reed-Solomon(RS)codes across different error correction coding types.The effects of unscattered photon ratio and depolarization ratio on BER are also verified.Finally,a UWOC system based on SPD is constructed,achieving 14.58 Mbps with polarization OOK multiplexing modulation and 4.37 Mbps with polarization 2-PPM multiplexing modulation using LDPC code error correction.
基金Supported by the National High-Tech Research and Development Plan of China(No.2007AA120302)
文摘A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.
文摘In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper, the complementary error function is proposed instead of the cubic spline function as the transition zone function, due to the availability of analytical expression of its derivatives and the nonnegativity fact. It is shown that with the use of the complementary error function, transition zones for all refractive types work correctly.
文摘In this paper, we present two new algorithms in residue number systems for scaling and error correction. The first algorithm is the Cyclic Property of Residue-Digit Difference (CPRDD). It is used to speed up the residue multiple error correction due to its parallel processes. The second is called the Target Race Distance (TRD). It is used to speed up residue scaling. Both of these two algorithms are used without the need for Mixed Radix Conversion (MRC) or Chinese Residue Theorem (CRT) techniques, which are time consuming and require hardware complexity. Furthermore, the residue scaling can be performed in parallel for any combination of moduli set members without using lookup tables.
文摘Through the analysis for the process of Walsh modulation and demodula tion,the adaptive error-limiting method suitable for the Walsh code shutting multiplex ing in the mine monitor system is advanced in this article. It is proved by theoretical analysis and circuit experiments that this method is easy to carry out and can not only improve the quality of information transmission but also meet the requirement of the system patrol test time without the increasement of system investment.
基金the National Natural Science Foundation of China(Nos.12035019,11690041,and 11805244).
文摘A dual double interlocked storage cell(DICE)interleaving layout static random-access memory(SRAM)is designed and manufactured based on 65 nm bulk complementary metal oxide semiconductor technology.The single event upset(SEU)cross sections of this memory are obtained via heavy ion irradiation with a linear energy transfer(LET)value ranging from 1.7 to 83.4 MeV/(mg/cm^(2)).Experimental results show that the upset threshold(LETth)of a 4 KB block is approximately 6 MeV/(mg/cm^(2)),which is much better than that of a standard unhardened SRAM with an identical technology node.A 1 KB block has a higher LETth of 25 MeV/(mg/cm^(2))owing to the use of the error detection and correction(EDAC)code.For a Ta ion irradiation test with the highest LET value(83.4 MeV/(mg/cm^(2))),the benefit of the EDAC code is reduced significantly because the multi-bit upset proportion in the SEU is increased remarkably.Compared with normal incident ions,the memory exhibits a higher SEU sensitivity in the tilt angle irradiation test.Moreover,the SEU cross section indicates a significant dependence on the data pattern.When comprehensively considering HSPICE simulation results and the sensitive area distributions of the DICE cell,it is shown that the data pattern dependence is primarily associated with the arrangement of sensitive transistor pairs in the layout.Finally,some suggestions are provided to further improve the radiation resistance of the memory.By implementing a particular design at the layout level,the SEU tolerance of the memory is improved significantly at a low area cost.Therefore,the designed 65 nm SRAM is suitable for electronic systems operating in serious radiation environments.
文摘According to the data from Investigation Report of Land Use Change in China,The Land Resources Communique of China and Chronicle of Statistical Data for Five Decades of New China issued from Ministry of Land Resources,we select two indices:change of farmland quantity and policy of farmland protection.According to econometric theory,by using Eviewes 5.1 software,co-integration analysis,Granger causality test,impulse response and other analysis methods,we analyze the relationship between change of farmland quantity and policy of farmland protection in China since the reform and opening-up.The results show that there is long-term balanced relationship between change of farmland quantity and policy of farmland protection,and there is a certain mechanism restricting motion of variables between the two so as to make the two deviate from each other little and step towards balance in the long run;there is unilateral causality relationship between farmland change and policy of farmland protection,namely that the farmland change is the Granger cause of policy of farmland protection,while policy of farmland protection is not the Granger cause of farmland change;impulse response and variance decomposition indicate that farmland change plays the role of promoting policy of farmland protection continuously,and the role is strengthened along with prolonged lag period;the policy of farmland protection has strong inertia,because it is impacted by the former level of itself,and the policy of farmland protection plays insignificant role in promoting farmland quantity.Consequently,the important approach of solving problem of rapid decrease of farmland is to formulate long-term strategy,strengthen theoretical research of farmland protection and reinforce degree of formulation,implementation and surveillance of farmland protection policy.
基金Supported by the National Natural Science Foundations of China （No. 60773003, 60970120, 60903180）, the Natural Science Basic Research Plan in Shanx/Province of China （No. S JOB -ZTI4 ）, and the Fundamental Research Funds For the Central Universities and the 111 Project （ No. B08038 ）.
