Aiming at the poor performance of the parity check(PC) aided adaptive successive cancellation list(PC-ASCL) decoding algorithm because the PC code in the polar code can only verify odd errors, an optimized parity chec...Aiming at the poor performance of the parity check(PC) aided adaptive successive cancellation list(PC-ASCL) decoding algorithm because the PC code in the polar code can only verify odd errors, an optimized parity check(OPC) code which can verify all odd errors as well as the half even errors is proposed. The OPC code is used to improve the PC-ASCL decoding algorithm, thus an OPC aided ASCL(OPC-ASCL) decoding algorithm is proposed. In the coding stage, the algorithm divides the information sequence into multiple segments, and places an OPC code at the end of each segment to verify the current information sequence, and places a cyclic redundancy check code at the end of the entire information sequence to verify the entire information sequence. In the decoding stage, the algorithm uses the OPC-ASCL decoder to decode. Simulation results show that compared to the PC-ASCL decoding algorithm, the OPC-ASCL decoding algorithm can reduce the complexity and obtain the certain performance gain.展开更多
Quantum error correction technology is based on the principle of redundant encoding,encoding logical quantum information into multiple physical qubits to provide important support for the stable operation of quantum c...Quantum error correction technology is based on the principle of redundant encoding,encoding logical quantum information into multiple physical qubits to provide important support for the stable operation of quantum computers.To address the issues of low decoding accuracy and limited feature extraction in quantum error correction,this paper proposes a toric code decoder based on a syndrome-preliminary error fusion module(SPEFM)and a ResNet architecture.This decoder takes full advantage of the correlations between X and Z errors.In the SPEFM,the syndrome and preliminary error predictions are deeply fused,while a unidirectional Swin transformer architecture is incorporated to extract global error features from the syndrome data,signiffiificantly improving both decoding accuracy and computational efffiificiency.In addition,this paper further extracts local error features from the fused features using the deep residual structure of ResNet,enhancing the decoder's ability to capture quantum error patterns.Experimental results show that the decoder is applicable to different code distances(d=4,6,8,10)under the depolarizing noise model.Its bit error rate is lower than that of the minimum weight perfect matching(MWPM)algorithm,and its logical error rate is lower than both the MWPM algorithm and the ResNet18 decoder.Furthermore,the decoding threshold is increased to 0.163,representing a 3.82%improvement over the MWPM algorithm threshold of 0.157.展开更多
Implementing check node(CN)update based on the minimum value(MV)and second MV of incoming message magnitudes is crucial for Min-Sum Algorithms(MSAs).In the category of bit-serial implementations,existing schemes suffe...Implementing check node(CN)update based on the minimum value(MV)and second MV of incoming message magnitudes is crucial for Min-Sum Algorithms(MSAs).In the category of bit-serial implementations,existing schemes suffer from decoding performance degradation,large hardware areas,and/or long latency.In this paper,we propose two efficient CN update functions based on the MV and an approximate second MV,and design bit-serial architectures to implement them.Simulation results show that our functions exhibit the minimum decoding performance degradation compared to the existing functions using approximate second MVs.Moreover,the applicationspecific integrated circuits(ASIC)implementation results demonstrate the advantages of our architectures in terms of area,latency,etc.展开更多
In this work,we propose a multi-attempt successive cancellation list(MA-SCL)decoder for polar codes that achieves identical error-correction performance to standard SCL decoding while reducing average complexity.Unlik...In this work,we propose a multi-attempt successive cancellation list(MA-SCL)decoder for polar codes that achieves identical error-correction performance to standard SCL decoding while reducing average complexity.Unlike CRC-aided SCL,the proposed MA-SCL progressively restarts decoding with increasing list sizes and reuses information from previous attempts.This design eliminates the need for outer CRC codes.The decoder features dynamic searchspace pruning and an early stopping criterion based on path metrics.Simulations show MA-SCL matches SCL performance with lower average complexity,particularly for short polar-like codes with reed-muller(RM)rate profiles and dynamic frozen constraints.Compared to existing adaptive decoders,MA-SCL offers implementation advantages by eliminating the need for stack-/heap management while providing relatively stable latency bounds(1×to|Λ|×SCL latency).展开更多
Meteor burst channels(MBC)exhibit significant randomness and non-stationarity,limiting the effectiveness of traditional fixed-rate transmission strategies.This paper proposes an adaptive coding and modulation(ACM)sche...Meteor burst channels(MBC)exhibit significant randomness and non-stationarity,limiting the effectiveness of traditional fixed-rate transmission strategies.This paper proposes an adaptive coding and modulation(ACM)scheme based on real-time channel state perception using enhanced Turbo codes.By leveraging the interleaving structure of Turbo codes to mitigate channel fading and incorporating multi-rate adaptation,the scheme dynamically adjusts symbol rate,modulation,and coding methods to improve spectral efficiency.Meanwhile,a joint evaluation mechanism integrating physical-layer signal to noise ratio(SNR)estimation and media access control(MAC)-layer frame error rate(FER)statistics is introduced to achieve dynamic optimization of switching thresholds in multipath channels.Simulation and experimental results demonstrate that the proposed scheme significantly enhances system adaptability to MBC,and increases data transmission success rates,offering a more efficient and reliable solution for MBC systems.展开更多
Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementa...Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementation of low-density paritycheck(LDPC)decoding under resource-restricted space platforms.Particularly,due to the supply restriction and cost issues of high-speed on-board devices such as analog-to-digital converters(ADCs),the input of LDPC decoding will be usually constrained by hard-decision channel output.To tackle this challenge,density-evolution-based theoretical analysis is firstly performed to identify the cause of performance degradation in the conventional binaryinitialized iterative decoding(BIID)algorithm.Then,a computation-efficient decoding algorithm named multiary-initialized iterative decoding with early termination(MIID-ET)is proposed,which improves the error-correcting performance and computation efficiency by using a reliability-based initialization method and a threshold-based decoding termination rule.Finally,numerical simulations are conducted on example codes of rates 7/8 and 1/2 to evaluate the performance of different LDPC decoding algorithms,where the proposed MIID-ET outperforms the BIID with a coding gain of 0.38 dB and variable node calculation saving of 37%.With this advantage,the proposed MIID-ET can notably reduce LDPC decoder’s hardware implementation complexity under the same bit error rate performance,which successfully doubles the total throughput to 10 Gbps on a single-chip FPGA.展开更多
Constituted by BCH component codes and its ordered statistics decoding(OSD),the successive cancellation list(SCL)decoding of U-UV structural codes can provide competent error-correction performance in the short-to-med...Constituted by BCH component codes and its ordered statistics decoding(OSD),the successive cancellation list(SCL)decoding of U-UV structural codes can provide competent error-correction performance in the short-to-medium length regime.However,this list decoding complexity becomes formidable as the decoding output list size increases.This is primarily incurred by the OSD.Addressing this challenge,this paper proposes the low complexity SCL decoding through reducing the complexity of component code decoding,and pruning the redundant SCL decoding paths.For the former,an efficient skipping rule is introduced for the OSD so that the higher order decoding can be skipped when they are not possible to provide a more likely codeword candidate.It is further extended to the OSD variant,the box-andmatch algorithm(BMA),in facilitating the component code decoding.Moreover,through estimating the correlation distance lower bounds(CDLBs)of the component code decoding outputs,a path pruning(PP)-SCL decoding is proposed to further facilitate the decoding of U-UV codes.In particular,its integration with the improved OSD and BMA is discussed.Simulation results show that significant complexity reduction can be achieved.Consequently,the U-UV codes can outperform the cyclic redundancy check(CRC)-polar codes with a similar decoding complexity.展开更多
To improve the decoding performance of quantum error-correcting codes in asymmetric noise channels,a neural network-based decoding algorithm for bias-tailored quantum codes is proposed.The algorithm consists of a bias...To improve the decoding performance of quantum error-correcting codes in asymmetric noise channels,a neural network-based decoding algorithm for bias-tailored quantum codes is proposed.The algorithm consists of a biased noise model,a neural belief propagation decoder,a convolutional optimization layer,and a multi-objective loss function.The biased noise model simulates asymmetric error generation,providing a training dataset for decoding.The neural network,leveraging dynamic weight learning and a multi-objective loss function,mitigates error degeneracy.Additionally,the convolutional optimization layer enhances early-stage convergence efficiency.Numerical results show that for bias-tailored quantum codes,our decoder performs much better than the belief propagation(BP)with ordered statistics decoding(BP+OSD).Our decoder achieves an order of magnitude improvement in the error suppression compared to higher-order BP+OSD.Furthermore,the decoding threshold of our decoder for surface codes reaches a high threshold of 20%.展开更多
We study the performance of high-dimensional superdense coding(HD-SDC)over an amplitude damping(AD)channel with memory and propose a protocol that leverages partial measurement and its reversal to enhance the channel ...We study the performance of high-dimensional superdense coding(HD-SDC)over an amplitude damping(AD)channel with memory and propose a protocol that leverages partial measurement and its reversal to enhance the channel capacity.By considering a two-qutrit system,we model the memory AD noise using a convex mixture of memoryless and perfectly memory AD channels.We demonstrate that the memory effect alone can mitigate the decay of the SDC capacity under noise.More significantly,we show that the application of partial measurement before the channel and its reversal after the channel can not only recover the capacity degraded by noise but,for certain non-maximally entangled initial states,even amplify it beyond the initial capacity.This amplification effect is governed by three key factors:the ground-state probability in the initial entangled state,the memory strength,and the partial measurement strength.Our results provide a practical strategy for enhancing quantum communication protocols in realistic noisy environments and highlight the synergistic benefits of memory noise and measurement-based control.展开更多
Lossy image coding is the art of computing that is principally bounded by the image’s rate-distortion function.This bound,though never accurately characterized,has been approached practically via deep learning techno...Lossy image coding is the art of computing that is principally bounded by the image’s rate-distortion function.This bound,though never accurately characterized,has been approached practically via deep learning technologies in recent years.Indeed,learned image coding schemes allow direct optimization of the joint rate-distortion cost,thereby outperforming the handcrafted image coding schemes by a large margin.Still,it is observed that there is room for further improvement in the rate-distortion performance of learned image coding.In this article,we identify the gap between the ideal rate-distortion function forecasted by Shannon’s information theory and the empirical rate-distortion function achieved by the state-of-the-art learned image coding schemes,revealing that the gap is incurred by five different effects:modeling effect,approximation effect,amortization effect,digitization effect,and asymptotic effect.We design simulations and experiments to quantitatively evaluate the last three effects,which demonstrates the high potential of future lossy image coding technologies.展开更多
The ultracold neutron(UCN)transport code,MCUCN,designed initially for simulating UCN transportation from a solid deuterium(SD_2)source and neutron electric dipole moment experiments,could not simulate UCN storage and ...The ultracold neutron(UCN)transport code,MCUCN,designed initially for simulating UCN transportation from a solid deuterium(SD_2)source and neutron electric dipole moment experiments,could not simulate UCN storage and transportation in a superfluid4He(SFHe,He-Ⅱ)source accurately.This limitation arose from the absence of an4He upscattering mechanism and the absorption of3He.And the provided source energy distribution in MCUCN is different from that in SFHe source.This study introduced enhancements to MCUCN to address these constraints,explicitly incorporating the4He upscattering effect,the absorption of3He,the loss caused by impurities on converter wall,UCN source energy distribution in SFHe,and the transmission through negative optical potential.Additionally,a Python-based visualization code for intermediate states and results was developed.To validate these enhancements,we systematically compared the simulation results of the Lujan Center Mark3 UCN system by MCUCN and the improved MCUCN code(iMCUCN)with UCNtransport simulations.Additionally,we compared the results of the SUN1 system simulated by MCUCN and iMCUCN with measurement results.The study demonstrates that iMCUCN effectively simulates the storage and transportation of ultracold neutrons in He-Ⅱ.展开更多
This paper presents a reliability-based code calibration procedure aimed at determining optimal partial safety factors to be employed in design rules for pultruded glass fibre-reinforced polymer(pGFRP)I-section beams,...This paper presents a reliability-based code calibration procedure aimed at determining optimal partial safety factors to be employed in design rules for pultruded glass fibre-reinforced polymer(pGFRP)I-section beams,susceptible to web-crippling,namely under end-two-flange(ETF)and interior-two-flange(ITF)loading cases with unfastened flanges.Following a comprehensive state-of-the-art literature overview regarding web-crippling of pGFRP beams,the description of a direct strength method(DSM)-based resistance model for the two web-crippling loading cases is presented.Next,attention is turned to the detailed description of the(structural)reliability-based code calibration procedure for both loading cases.This includes detailing all the necessary steps and pertinent data,encompassing the adopted probabilistic models for material prop-erties,loads,geometrical dimensions,and resistance model uncertainty.Then,the results obtained through the application of the code calibration procedure are presented,validated,and discussed.Lastly,the paper closes by presenting relevant concluding remarks,which include recommendations for the partial safety fac-tors to be applied in the resistance model for pGFRP I-beams under ETF and ITF loading cases.展开更多
In erasure-coded storage systems,updating data requires parity maintenance,which often leads to significant I/O amplification due to“write-after-read”operations.Furthermore,scattered parity placement increases disk ...In erasure-coded storage systems,updating data requires parity maintenance,which often leads to significant I/O amplification due to“write-after-read”operations.Furthermore,scattered parity placement increases disk seek overhead during repair,resulting in degraded system performance.To address these challenges,this paper proposes a Cognitive Update and Repair Method(CURM)that leverages machine learning to classify files into writeonly,read-only,and read-write categories,enabling tailored update and repair strategies.For write-only and read-write files,CURM employs a data-differencemechanism combined with fine-grained I/O scheduling to minimize redundant read operations and mitigate I/O amplification.For read-write files,CURM further reserves adjacent disk space near parity blocks,supporting parallel reads and reducing disk seek overhead during repair.We implement CURM in a prototype system,Cognitive Update and Repair File System(CURFS),and conduct extensive experiments using realworld Network File System(NFS)and Microsoft Research(MSR)workloads on a 25-node cluster.Experimental results demonstrate that CURMimproves data update throughput by up to 82.52%,reduces recovery time by up to 47.47%,and decreases long-term storage overhead by more than 15% compared to state-of-the-art methods including Full Logging(FL),ParityLogging(PL),ParityLoggingwithReservedspace(PLR),andPARIX.These results validate the effectiveness of CURM in enhancing both update and repair performance,providing a scalable and efficient solution for large-scale erasure-coded storage systems.展开更多
Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also req...Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also require rate-matching.To this end,we first analyze the limitations of existing shortening patterns for PAC codes and explore their feasibility.Subsequently,we propose a novel shortening scheme for PAC codes based on list decoding,where the receiver is allowed to treat the values of the deleted bits as undetermined.This ap⁃proach uses a specialized PAC codeword and activates multiple decoding paths during the initialization of list decoding,enabling it to achieve the desired reliability.展开更多
Karst landscapes are developed on soluble rocks(primarily limestone),covering about 10-15%of Earth’s ice-free land surface(Ford and Williams,2007).Their unique geological properties have given rise to complex,heterog...Karst landscapes are developed on soluble rocks(primarily limestone),covering about 10-15%of Earth’s ice-free land surface(Ford and Williams,2007).Their unique geological properties have given rise to complex,heterogeneous,and“island-like”habitats that,combined with periodic drought,high calcium,and lownutrient stresses,foster high species diversity and endemism(Clements et al.,2006;Hao et al.,2015;Oliver et al.,2017;Monro et al.,2018).These conditions make karst ecosystems ideal“natural laboratories”for studying speciation and adaptive evolution(Clements et al.,2006;Oliver et al.,2017).展开更多
This paper conducts an empirical study on students'code modification behaviors in incremental programming projects by analyzing 40771 code submissions from 371 students through abstract syntax tree(AST)difference ...This paper conducts an empirical study on students'code modification behaviors in incremental programming projects by analyzing 40771 code submissions from 371 students through abstract syntax tree(AST)difference analysis and manual annotation.The study investigates the distribution of code modification types to prior-phase code during iterative development,identifies cross-phase error types,and analyzes refactoring strategies.The findings reveal that error correction and code refactoring constitute the primary types of cross-phase code modifications.Among cross-phase latent errors,special case neglect represents the dominant error type,indicating insufficient coverage of special scenarios in existing test suites.Variable renaming emerges as the most prevalent refactoring behavior,reflecting students'emphasis on code readability.These research findings provide empirical evidence for optimizing incremental curriculum design,improving test cases,and cultivating students'code maintenance capabilities in programming education.展开更多
Theoretical and computational chemistry has profoundly impacted a wide range of disciplines,from chemistry and physics to biology and materials science.In recent years,remarkable advances in electronic structure theor...Theoretical and computational chemistry has profoundly impacted a wide range of disciplines,from chemistry and physics to biology and materials science.In recent years,remarkable advances in electronic structure theory,molecular dynamics,and machine learning methods——coupled with increasingly powerful algorithms and software—have equipped chemists with an unprecedented arsenal of tools to tackle complex chemical problems.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U21A20447 and 61971079)。
摘要Aiming at the poor performance of the parity check(PC) aided adaptive successive cancellation list(PC-ASCL) decoding algorithm because the PC code in the polar code can only verify odd errors, an optimized parity check(OPC) code which can verify all odd errors as well as the half even errors is proposed. The OPC code is used to improve the PC-ASCL decoding algorithm, thus an OPC aided ASCL(OPC-ASCL) decoding algorithm is proposed. In the coding stage, the algorithm divides the information sequence into multiple segments, and places an OPC code at the end of each segment to verify the current information sequence, and places a cyclic redundancy check code at the end of the entire information sequence to verify the entire information sequence. In the decoding stage, the algorithm uses the OPC-ASCL decoder to decode. Simulation results show that compared to the PC-ASCL decoding algorithm, the OPC-ASCL decoding algorithm can reduce the complexity and obtain the certain performance gain.
基金supported by the Joint Fund of the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2022LLZ012 and ZR2021LLZ001)the Key Research and Development Program of Shandong Province,China(Grant No.2023CXGC010901)。
摘要Quantum error correction technology is based on the principle of redundant encoding,encoding logical quantum information into multiple physical qubits to provide important support for the stable operation of quantum computers.To address the issues of low decoding accuracy and limited feature extraction in quantum error correction,this paper proposes a toric code decoder based on a syndrome-preliminary error fusion module(SPEFM)and a ResNet architecture.This decoder takes full advantage of the correlations between X and Z errors.In the SPEFM,the syndrome and preliminary error predictions are deeply fused,while a unidirectional Swin transformer architecture is incorporated to extract global error features from the syndrome data,signiffiificantly improving both decoding accuracy and computational efffiificiency.In addition,this paper further extracts local error features from the fused features using the deep residual structure of ResNet,enhancing the decoder's ability to capture quantum error patterns.Experimental results show that the decoder is applicable to different code distances(d=4,6,8,10)under the depolarizing noise model.Its bit error rate is lower than that of the minimum weight perfect matching(MWPM)algorithm,and its logical error rate is lower than both the MWPM algorithm and the ResNet18 decoder.Furthermore,the decoding threshold is increased to 0.163,representing a 3.82%improvement over the MWPM algorithm threshold of 0.157.
基金supported by National Natural Science Foundation of China(NSFC)under Grant 62571455,Grant 62371401,and Grant 62331002supported by the SingaporeMinistry of Education Academic Research Fund Tier 2 T2EP50221-0036.
摘要Implementing check node(CN)update based on the minimum value(MV)and second MV of incoming message magnitudes is crucial for Min-Sum Algorithms(MSAs).In the category of bit-serial implementations,existing schemes suffer from decoding performance degradation,large hardware areas,and/or long latency.In this paper,we propose two efficient CN update functions based on the MV and an approximate second MV,and design bit-serial architectures to implement them.Simulation results show that our functions exhibit the minimum decoding performance degradation compared to the existing functions using approximate second MVs.Moreover,the applicationspecific integrated circuits(ASIC)implementation results demonstrate the advantages of our architectures in terms of area,latency,etc.
基金supported by the 2025 Start-up Research Fund(Grant No.JIH2333002Y)from Fudan Universitysupported in part by the Fundamental Research Funds for the Central Universities+3 种基金the Yangtze River Delta Science and Technology Innovation Community Joint Research(Basic Research)Project under Grant BK20244006111 project BP0719010STCSM 22DZ2229005supported by the National Natural Science Foundation of China Grant No.62595745
摘要In this work,we propose a multi-attempt successive cancellation list(MA-SCL)decoder for polar codes that achieves identical error-correction performance to standard SCL decoding while reducing average complexity.Unlike CRC-aided SCL,the proposed MA-SCL progressively restarts decoding with increasing list sizes and reuses information from previous attempts.This design eliminates the need for outer CRC codes.The decoder features dynamic searchspace pruning and an early stopping criterion based on path metrics.Simulations show MA-SCL matches SCL performance with lower average complexity,particularly for short polar-like codes with reed-muller(RM)rate profiles and dynamic frozen constraints.Compared to existing adaptive decoders,MA-SCL offers implementation advantages by eliminating the need for stack-/heap management while providing relatively stable latency bounds(1×to|Λ|×SCL latency).
摘要Meteor burst channels(MBC)exhibit significant randomness and non-stationarity,limiting the effectiveness of traditional fixed-rate transmission strategies.This paper proposes an adaptive coding and modulation(ACM)scheme based on real-time channel state perception using enhanced Turbo codes.By leveraging the interleaving structure of Turbo codes to mitigate channel fading and incorporating multi-rate adaptation,the scheme dynamically adjusts symbol rate,modulation,and coding methods to improve spectral efficiency.Meanwhile,a joint evaluation mechanism integrating physical-layer signal to noise ratio(SNR)estimation and media access control(MAC)-layer frame error rate(FER)statistics is introduced to achieve dynamic optimization of switching thresholds in multipath channels.Simulation and experimental results demonstrate that the proposed scheme significantly enhances system adaptability to MBC,and increases data transmission success rates,offering a more efficient and reliable solution for MBC systems.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1005000)the National Natural Science Foundation of China(Grant No.62101308 and 62025110).
摘要Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementation of low-density paritycheck(LDPC)decoding under resource-restricted space platforms.Particularly,due to the supply restriction and cost issues of high-speed on-board devices such as analog-to-digital converters(ADCs),the input of LDPC decoding will be usually constrained by hard-decision channel output.To tackle this challenge,density-evolution-based theoretical analysis is firstly performed to identify the cause of performance degradation in the conventional binaryinitialized iterative decoding(BIID)algorithm.Then,a computation-efficient decoding algorithm named multiary-initialized iterative decoding with early termination(MIID-ET)is proposed,which improves the error-correcting performance and computation efficiency by using a reliability-based initialization method and a threshold-based decoding termination rule.Finally,numerical simulations are conducted on example codes of rates 7/8 and 1/2 to evaluate the performance of different LDPC decoding algorithms,where the proposed MIID-ET outperforms the BIID with a coding gain of 0.38 dB and variable node calculation saving of 37%.With this advantage,the proposed MIID-ET can notably reduce LDPC decoder’s hardware implementation complexity under the same bit error rate performance,which successfully doubles the total throughput to 10 Gbps on a single-chip FPGA.
基金supported by the National Natural Science Foundation of China(NSFC)with project ID 62071498the Guangdong National Science Foundation(GDNSF)with project ID 2024A1515010213.
摘要Constituted by BCH component codes and its ordered statistics decoding(OSD),the successive cancellation list(SCL)decoding of U-UV structural codes can provide competent error-correction performance in the short-to-medium length regime.However,this list decoding complexity becomes formidable as the decoding output list size increases.This is primarily incurred by the OSD.Addressing this challenge,this paper proposes the low complexity SCL decoding through reducing the complexity of component code decoding,and pruning the redundant SCL decoding paths.For the former,an efficient skipping rule is introduced for the OSD so that the higher order decoding can be skipped when they are not possible to provide a more likely codeword candidate.It is further extended to the OSD variant,the box-andmatch algorithm(BMA),in facilitating the component code decoding.Moreover,through estimating the correlation distance lower bounds(CDLBs)of the component code decoding outputs,a path pruning(PP)-SCL decoding is proposed to further facilitate the decoding of U-UV codes.In particular,its integration with the improved OSD and BMA is discussed.Simulation results show that significant complexity reduction can be achieved.Consequently,the U-UV codes can outperform the cyclic redundancy check(CRC)-polar codes with a similar decoding complexity.
基金supported by the National Natural Science Foundation of China(Grant Nos.62371240,61802175,62401266,and 12201300)the National Key R&D Program of China(Grant No.2022YFB3103800)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20241452)the Fundamental Research Funds for the Central Universities(Grant No.30923011014)the fund of Laboratory for Advanced Computing and Intelligence Engineering(Grant No.2023-LYJJ-01-009)。
摘要To improve the decoding performance of quantum error-correcting codes in asymmetric noise channels,a neural network-based decoding algorithm for bias-tailored quantum codes is proposed.The algorithm consists of a biased noise model,a neural belief propagation decoder,a convolutional optimization layer,and a multi-objective loss function.The biased noise model simulates asymmetric error generation,providing a training dataset for decoding.The neural network,leveraging dynamic weight learning and a multi-objective loss function,mitigates error degeneracy.Additionally,the convolutional optimization layer enhances early-stage convergence efficiency.Numerical results show that for bias-tailored quantum codes,our decoder performs much better than the belief propagation(BP)with ordered statistics decoding(BP+OSD).Our decoder achieves an order of magnitude improvement in the error suppression compared to higher-order BP+OSD.Furthermore,the decoding threshold of our decoder for surface codes reaches a high threshold of 20%.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12265004 and 12534020)the Natural Science Foundation of Jiangxi Province(Grant No.20242BAB26010)+3 种基金the National Natural Science Foundation of China(Grant Nos.12565001 and 12205054)the Natural Science Foundation of Jiangxi Province(Grant No.20252BAC200163)the National Natural Science Foundation of China(Grant No.12365003)the Jiangxi Provincial Key Laboratory of Multidimensional Intelligent Perception and Control of China(Grant No.2024SSY03161)。
摘要We study the performance of high-dimensional superdense coding(HD-SDC)over an amplitude damping(AD)channel with memory and propose a protocol that leverages partial measurement and its reversal to enhance the channel capacity.By considering a two-qutrit system,we model the memory AD noise using a convex mixture of memoryless and perfectly memory AD channels.We demonstrate that the memory effect alone can mitigate the decay of the SDC capacity under noise.More significantly,we show that the application of partial measurement before the channel and its reversal after the channel can not only recover the capacity degraded by noise but,for certain non-maximally entangled initial states,even amplify it beyond the initial capacity.This amplification effect is governed by three key factors:the ground-state probability in the initial entangled state,the memory strength,and the partial measurement strength.Our results provide a practical strategy for enhancing quantum communication protocols in realistic noisy environments and highlight the synergistic benefits of memory noise and measurement-based control.
基金supported by the Fundamental Research Funds for the Central Universities(WK3490000006).
摘要Lossy image coding is the art of computing that is principally bounded by the image’s rate-distortion function.This bound,though never accurately characterized,has been approached practically via deep learning technologies in recent years.Indeed,learned image coding schemes allow direct optimization of the joint rate-distortion cost,thereby outperforming the handcrafted image coding schemes by a large margin.Still,it is observed that there is room for further improvement in the rate-distortion performance of learned image coding.In this article,we identify the gap between the ideal rate-distortion function forecasted by Shannon’s information theory and the empirical rate-distortion function achieved by the state-of-the-art learned image coding schemes,revealing that the gap is incurred by five different effects:modeling effect,approximation effect,amortization effect,digitization effect,and asymptotic effect.We design simulations and experiments to quantitatively evaluate the last three effects,which demonstrates the high potential of future lossy image coding technologies.
基金the National Key R&D Program of China(No.2024YFE0110001)the National Natural Science Foundation of China(U1932219)the Mobility Programme endorsed by the Joint Committee of the Sino-German Center(M0728)。
摘要The ultracold neutron(UCN)transport code,MCUCN,designed initially for simulating UCN transportation from a solid deuterium(SD_2)source and neutron electric dipole moment experiments,could not simulate UCN storage and transportation in a superfluid4He(SFHe,He-Ⅱ)source accurately.This limitation arose from the absence of an4He upscattering mechanism and the absorption of3He.And the provided source energy distribution in MCUCN is different from that in SFHe source.This study introduced enhancements to MCUCN to address these constraints,explicitly incorporating the4He upscattering effect,the absorption of3He,the loss caused by impurities on converter wall,UCN source energy distribution in SFHe,and the transmission through negative optical potential.Additionally,a Python-based visualization code for intermediate states and results was developed.To validate these enhancements,we systematically compared the simulation results of the Lujan Center Mark3 UCN system by MCUCN and the improved MCUCN code(iMCUCN)with UCNtransport simulations.Additionally,we compared the results of the SUN1 system simulated by MCUCN and iMCUCN with measurement results.The study demonstrates that iMCUCN effectively simulates the storage and transportation of ultracold neutrons in He-Ⅱ.
基金the Portuguese Founda-tion for Science and Technology(Fundação para a Ciência e Tec-nologia,FCT)(PTDC/ECI-EGC/3916/2021)for the financial supportsupported by the FCT through projects Laboratory of Energy,Transports and Aerospace(LAETA)Base Funding and LAETA Programatic Funding,Civil Engineering Research and Innovation for Sustainability(CERIS,UIDB/04625/2020)the Centre for Marine Technology and Ocean Engineering(CENTEC,UIDB/UIDP/00134/2020).
摘要This paper presents a reliability-based code calibration procedure aimed at determining optimal partial safety factors to be employed in design rules for pultruded glass fibre-reinforced polymer(pGFRP)I-section beams,susceptible to web-crippling,namely under end-two-flange(ETF)and interior-two-flange(ITF)loading cases with unfastened flanges.Following a comprehensive state-of-the-art literature overview regarding web-crippling of pGFRP beams,the description of a direct strength method(DSM)-based resistance model for the two web-crippling loading cases is presented.Next,attention is turned to the detailed description of the(structural)reliability-based code calibration procedure for both loading cases.This includes detailing all the necessary steps and pertinent data,encompassing the adopted probabilistic models for material prop-erties,loads,geometrical dimensions,and resistance model uncertainty.Then,the results obtained through the application of the code calibration procedure are presented,validated,and discussed.Lastly,the paper closes by presenting relevant concluding remarks,which include recommendations for the partial safety fac-tors to be applied in the resistance model for pGFRP I-beams under ETF and ITF loading cases.
基金supported by the National Natural Science Foundation of China(Grant No.62362019)the Natural Science Foundation of Hainan Province(Grant No.624RC482)the Hainan Provincial Higher Education Teaching Reform Research Project(Grant Hnjg2024-27).
摘要In erasure-coded storage systems,updating data requires parity maintenance,which often leads to significant I/O amplification due to“write-after-read”operations.Furthermore,scattered parity placement increases disk seek overhead during repair,resulting in degraded system performance.To address these challenges,this paper proposes a Cognitive Update and Repair Method(CURM)that leverages machine learning to classify files into writeonly,read-only,and read-write categories,enabling tailored update and repair strategies.For write-only and read-write files,CURM employs a data-differencemechanism combined with fine-grained I/O scheduling to minimize redundant read operations and mitigate I/O amplification.For read-write files,CURM further reserves adjacent disk space near parity blocks,supporting parallel reads and reducing disk seek overhead during repair.We implement CURM in a prototype system,Cognitive Update and Repair File System(CURFS),and conduct extensive experiments using realworld Network File System(NFS)and Microsoft Research(MSR)workloads on a 25-node cluster.Experimental results demonstrate that CURMimproves data update throughput by up to 82.52%,reduces recovery time by up to 47.47%,and decreases long-term storage overhead by more than 15% compared to state-of-the-art methods including Full Logging(FL),ParityLogging(PL),ParityLoggingwithReservedspace(PLR),andPARIX.These results validate the effectiveness of CURM in enhancing both update and repair performance,providing a scalable and efficient solution for large-scale erasure-coded storage systems.
基金supported in part by the National Natural Sciences Foun⁃dation of China(NSFC)under Grant Nos.62301185 and 62027802in part by ZTE Industry⁃University-Institute Cooperation Fundsin part by The Major Key Project of PCL under Grant No.PCL2024A01.
摘要Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also require rate-matching.To this end,we first analyze the limitations of existing shortening patterns for PAC codes and explore their feasibility.Subsequently,we propose a novel shortening scheme for PAC codes based on list decoding,where the receiver is allowed to treat the values of the deleted bits as undetermined.This ap⁃proach uses a specialized PAC codeword and activates multiple decoding paths during the initialization of list decoding,enabling it to achieve the desired reliability.
基金equally funded by the Joint Funds of the National Natural Science Foundation of China(U2571210)the Strategic Priority Research Program of Kunming Institute of Botany,Chinese Academy of Sciences(KIBXD202401)+2 种基金National Natural Science Foundation of China(32471734)the Yuelushan Laboratory Breeding Projectthe Caiyun Postdoctoral Program of Yunnan Province。
摘要Karst landscapes are developed on soluble rocks(primarily limestone),covering about 10-15%of Earth’s ice-free land surface(Ford and Williams,2007).Their unique geological properties have given rise to complex,heterogeneous,and“island-like”habitats that,combined with periodic drought,high calcium,and lownutrient stresses,foster high species diversity and endemism(Clements et al.,2006;Hao et al.,2015;Oliver et al.,2017;Monro et al.,2018).These conditions make karst ecosystems ideal“natural laboratories”for studying speciation and adaptive evolution(Clements et al.,2006;Oliver et al.,2017).
基金supported by the National Natural Science Foundation of China(Nos.62577007 and 92582204)。
摘要This paper conducts an empirical study on students'code modification behaviors in incremental programming projects by analyzing 40771 code submissions from 371 students through abstract syntax tree(AST)difference analysis and manual annotation.The study investigates the distribution of code modification types to prior-phase code during iterative development,identifies cross-phase error types,and analyzes refactoring strategies.The findings reveal that error correction and code refactoring constitute the primary types of cross-phase code modifications.Among cross-phase latent errors,special case neglect represents the dominant error type,indicating insufficient coverage of special scenarios in existing test suites.Variable renaming emerges as the most prevalent refactoring behavior,reflecting students'emphasis on code readability.These research findings provide empirical evidence for optimizing incremental curriculum design,improving test cases,and cultivating students'code maintenance capabilities in programming education.
摘要Theoretical and computational chemistry has profoundly impacted a wide range of disciplines,from chemistry and physics to biology and materials science.In recent years,remarkable advances in electronic structure theory,molecular dynamics,and machine learning methods——coupled with increasingly powerful algorithms and software—have equipped chemists with an unprecedented arsenal of tools to tackle complex chemical problems.