In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary rando...In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary random field in a small range,we give an entropy estimation and obtain the average entropy estimation formula in a certain bounded space region.It can be proven that the estimation of the average differential entropy converges to the theoretical value with a probability of 1.In addition,we also conducted numerical experiments for different parameters to verify the convergence result obtained in the theoretical proofs.展开更多
This paper studies a strongly convergent inertial forward-backward-forward algorithm for the variational inequality problem in Hilbert spaces.In our convergence analysis,we do not assume the on-line rule of the inerti...This paper studies a strongly convergent inertial forward-backward-forward algorithm for the variational inequality problem in Hilbert spaces.In our convergence analysis,we do not assume the on-line rule of the inertial parameters and the iterates,which have been assumed by several authors whenever a strongly convergent algorithm with an inertial extrapolation step is proposed for a variational inequality problem.Consequently,our proof arguments are different from what is obtainable in the relevant literature.Finally,we give numerical tests to confirm the theoretical analysis and show that our proposed algorithm is superior to related ones in the literature.展开更多
The heterogeneous variational nodal method(HVNM)has emerged as a potential approach for solving high-fidelity neutron transport problems.However,achieving accurate results with HVNM in large-scale problems using high-...The heterogeneous variational nodal method(HVNM)has emerged as a potential approach for solving high-fidelity neutron transport problems.However,achieving accurate results with HVNM in large-scale problems using high-fidelity models has been challenging due to the prohibitive computational costs.This paper presents an efficient parallel algorithm tailored for HVNM based on the Message Passing Interface standard.The algorithm evenly distributes the response matrix sets among processors during the matrix formation process,thus enabling independent construction without communication.Once the formation tasks are completed,a collective operation merges and shares the matrix sets among the processors.For the solution process,the problem domain is decomposed into subdomains assigned to specific processors,and the red-black Gauss-Seidel iteration is employed within each subdomain to solve the response matrix equation.Point-to-point communication is conducted between adjacent subdomains to exchange data along the boundaries.The accuracy and efficiency of the parallel algorithm are verified using the KAIST and JRR-3 test cases.Numerical results obtained with multiple processors agree well with those obtained from Monte Carlo calculations.The parallelization of HVNM results in eigenvalue errors of 31 pcm/-90 pcm and fission rate RMS errors of 1.22%/0.66%,respectively,for the 3D KAIST problem and the 3D JRR-3 problem.In addition,the parallel algorithm significantly reduces computation time,with an efficiency of 68.51% using 36 processors in the KAIST problem and 77.14% using 144 processors in the JRR-3 problem.展开更多
Underwater monopulse space-time adaptive track-before-detect method,which combines space-time adaptive detector(STAD)and the track-before-detect algorithm based on dynamic programming(DP-TBD),denoted as STAD-DP-TBD,ca...Underwater monopulse space-time adaptive track-before-detect method,which combines space-time adaptive detector(STAD)and the track-before-detect algorithm based on dynamic programming(DP-TBD),denoted as STAD-DP-TBD,can effectively detect low-speed weak targets.However,due to the complexity and variability of the underwater environment,it is difficult to obtain sufficient secondary data,resulting in a serious decline in the detection and tracking performance,and leading to poor robustness of the algorithm.In this paper,based on the adaptive matched filter(AMF)test and the RAO test,underwater monopulse AMF-DP-TBD algorithm and RAO-DP-TBD algorithm which incorporate persymmetry and symmetric spectrum,denoted as PSAMF-DP-TBD and PS-RAO-DP-TBD,are proposed and compared with the AMF-DP-TBD algorithm and RAO-DP-TBD algorithm based on persymmetry array,denoted as P-AMF-DP-TBD and P-RAO-DP-TBD.The simulation results show that the four methods can work normally with sufficient secondary data and slightly insufficient secondary data,but when the secondary data is severely insufficient,the P-AMF-DP-TBD and P-RAO-DP-TBD algorithms has failed while the PSAMF-DP-TBD and PS-RAO-DP-TBD algorithms still have good detection and tracking capabilities.展开更多
Video transmission requires considerable bandwidth,and current widely employed schemes prove inadequate when confronted with scenes featuring prominently.Motivated by the strides in talkinghead generative technology,t...Video transmission requires considerable bandwidth,and current widely employed schemes prove inadequate when confronted with scenes featuring prominently.Motivated by the strides in talkinghead generative technology,the paper introduces a semantic transmission system tailored for talking-head videos.The system captures semantic information from talking-head video and faithfully reconstructs source video at the receiver,only one-shot reference frame and compact semantic features are required for the entire transmission.Specifically,we analyze video semantics in the pixel domain frame-by-frame and jointly process multi-frame semantic information to seamlessly incorporate spatial and temporal information.Variational modeling is utilized to evaluate the diversity of importance among group semantics,thereby guiding bandwidth resource allocation for semantics to enhance system efficiency.The whole endto-end system is modeled as an optimization problem and equivalent to acquiring optimal rate-distortion performance.We evaluate our system on both reference frame and video transmission,experimental results demonstrate that our system can improve the efficiency and robustness of communications.Compared to the classical approaches,our system can save over 90%of bandwidth when user perception is close.展开更多
Leveraging the extraordinary phenomena of quantum superposition and quantum correlation,quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical computers.This paper tac...Leveraging the extraordinary phenomena of quantum superposition and quantum correlation,quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical computers.This paper tackles two pivotal challenges in the realm of quantum computing:firstly,the development of an effective encoding protocol for translating classical data into quantum states,a critical step for any quantum computation.Different encoding strategies can significantly influence quantum computer performance.Secondly,we address the need to counteract the inevitable noise that can hinder quantum acceleration.Our primary contribution is the introduction of a novel variational data encoding method,grounded in quantum regression algorithm models.By adapting the learning concept from machine learning,we render data encoding a learnable process.This allowed us to study the role of quantum correlation in data encoding.Through numerical simulations of various regression tasks,we demonstrate the efficacy of our variational data encoding,particularly post-learning from instructional data.Moreover,we delve into the role of quantum correlation in enhancing task performance,especially in noisy environments.Our findings underscore the critical role of quantum correlation in not only bolstering performance but also in mitigating noise interference,thus advancing the frontier of quantum computing.展开更多
Recently,deep learning-based semantic communication has garnered widespread attention,with numerous systems designed for transmitting diverse data sources,including text,image,and speech,etc.While efforts have been di...Recently,deep learning-based semantic communication has garnered widespread attention,with numerous systems designed for transmitting diverse data sources,including text,image,and speech,etc.While efforts have been directed toward improving system performance,many studies have concentrated on enhancing the structure of the encoder and decoder.However,this often overlooks the resulting increase in model complexity,imposing additional storage and computational burdens on smart devices.Furthermore,existing work tends to prioritize explicit semantics,neglecting the potential of implicit semantics.This paper aims to easily and effectively enhance the receiver's decoding capability without modifying the encoder and decoder structures.We propose a novel semantic communication system with variational neural inference for text transmission.Specifically,we introduce a simple but effective variational neural inferer at the receiver to infer the latent semantic information within the received text.This information is then utilized to assist in the decoding process.The simulation results show a significant enhancement in system performance and improved robustness.展开更多
Zero-carbon parks have broad prospects in carbon neutralization.As an energy hub,hydrogen energy storage plays an important role in zero-carbon parks.However,the nonlinear characteristics of hydrogen energy storage sy...Zero-carbon parks have broad prospects in carbon neutralization.As an energy hub,hydrogen energy storage plays an important role in zero-carbon parks.However,the nonlinear characteristics of hydrogen energy storage systems(HESSs)have a significant impact on the system economy.Therefore,considering the variable working condition characteristics of HESSs,a hybrid operation method is proposed for HESS,to support the efficient and economic operation of zero-carbon parks,By analyzing the operating principle of a zero-carbon park with HESS,the system structure framework and variable condition linearization model of the equipment in HESS are established.Moreover,considering the energy output characteristics of hydrogen energy storage equipment under variable working conditions,a multimodule hybrid operation strategy is proposed for electrolytic and fuel cells,effectively meeting the thermoelectric load demand of zero-carbon parks in different scenarios.Finally,the economy of the proposed hybrid operation strategy was verified in typical scenarios,using a zero-carbon park embedded with a HESS.展开更多
Cell-to-cell variations(CtCV) compromise the electrochemical performance of battery packs, yet the evolutional mechanism and quantitative impacts of CtCV on the pack's fast-charging performance remain unexplored. ...Cell-to-cell variations(CtCV) compromise the electrochemical performance of battery packs, yet the evolutional mechanism and quantitative impacts of CtCV on the pack's fast-charging performance remain unexplored. This knowledge gap is vital for the proliferation of electric vehicles. This study underlies the relationship between CtCV and charging performance by assessing the pack's charge speed, final electric quantity, and temperature consistency. Cell variations and pack status are depicted using 2D parameter diagrams, and an m PnS configured pack model is built upon a decomposed electrode cell model.Variations in three single electric parameters, i.e., capacity(Q), electric quantity(E), and internal resistance(R), and their dual interactions, i.e., E-Q and R-Q, are analyzed carefully. The results indicate that Q variations predominantly affect the final electric quantity of the pack, while R variations impact the charge speed most. With incremental variances in cell parameters, the pack's fast-charging capability first declines linearly and then deteriorates sharply as variations intensify. This research elucidates the correlations between pack charging capabilities and cell variations, providing essential insights for optimizing cell sorting and assembly, battery management design, and charging protocol development for battery packs.展开更多
Typhoons are becoming frequent and intense with ongoing climate change,threatening ecological security and healthy forest development in coastal areas.Eucalyptus of a predominant introduced species in southern China,f...Typhoons are becoming frequent and intense with ongoing climate change,threatening ecological security and healthy forest development in coastal areas.Eucalyptus of a predominant introduced species in southern China,faces significant growth challenges because of typhoon.Therefore,it is vital to investigate the variation of related traits and select superior breeding materials for genetic improvement.Variance,genetic parameter,and correlation analyses were carried out on wind damage indices and eight wood proper-ties in 88 families from 11 provenances of 10-year-old Euca-lyptus camaldulensis.The selection index equation was used for evaluating multiple traits and selecting superior prov-enances and family lines as future breeding material.The results show that all traits were highly significantly differ-ent at provenance and family levels,with the wind damage index having the highest coefficient of genetic variation.The heritability of each trait ranged from 0.48 to 0.87,with the wind damage index,lignin and hemicellulose contents,and microfibril angle having the highest heritabilities.The wind damage index had a positive genetic correlation with wood density,a negative correlation with lignin content,a negative phenotypic correlation and a negative genetic correlation with microfibril angle.Wind damage index and genetic progress in the selection of eight wood traits varied from 7.2%to 614.8%.Three provenances and 12 superior families were selected.The genetic gains of the wind damage index were 10.2%and 33.9%for provenances and families,and these may be starting material for genetic modification for wind resistance in eucalyptus and for their dissemination to typhoon-prone coastal areas of southern China.展开更多
Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant func...Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.展开更多
Characterizing foliar trait variation in sun and shade leaves can provide insights into inter-and intra-species resource use strategies and plant response to environmental change.However,datasets with records of multi...Characterizing foliar trait variation in sun and shade leaves can provide insights into inter-and intra-species resource use strategies and plant response to environmental change.However,datasets with records of multiple foliar traits from the same individual and including shade leaves are sparse,which limits our ability to investigate trait-trait,trait-environment relationships and trait coordination in both sun and shade leaves.We presented a comprehensive dataset of 15 foliar traits from sun and shade leaves sampled with leaf spectroscopy,including 424 individuals of 110 plant species from 19 sites across eastern North America.We investigated trait variation,covariation,scaling relationships with leaf mass,and the effects of environment,canopy position,and taxonomy on trait expression.Generally,sun leaves had higher leaf mass per area,nonstructural carbohydrates and total phenolics,lower mass-based chlorophyll a+b,carotenoids,phosphorus,and potassium,but exhibited species-specific characteristics.Covariation between sun and shade leaf traits,and trait-environment relationships were overall consistent across species.The main dimensions of foliar trait variation in seed plants were revealed including leaf economics traits,photosynthetic pigments,defense,and structural traits.Taxonomy and canopy position collectively explained most of the foliar trait variation.This study highlights the importance of including intra-individual and intra-specific trait variation to improve our understanding of ecosystem functions.Our findings have implications for efficient field sampling,and trait mapping with remote sensing.展开更多
Remote reflection waves, essential for acquiring high-resolution images of geological structures beyond boreholes, often suffer contamination from strong direct mode waves propagating along the borehole.Consequently, ...Remote reflection waves, essential for acquiring high-resolution images of geological structures beyond boreholes, often suffer contamination from strong direct mode waves propagating along the borehole.Consequently, the extraction of weak reflected waves becomes pivotal for optimizing migration image quality. This paper introduces a novel approach to extracting reflected waves by sequentially operating in the spatial frequency and curvelet domains. Using variation mode decomposition(VMD), single-channel spatial domain signals within the common offset gather are iteratively decomposed into high-wavenumber and low-wavenumber intrinsic mode functions(IMFs). The low-wavenumber IMF is then subtracted from the overall waveform to attenuate direct mode waves. Subsequently, the curvelet transform is employed to segregate upgoing and downgoing reflected waves within the filtered curvelet domain. As a result, direct mode waves are substantially suppressed, while the integrity of reflected waves is fully preserved. The efficacy of this approach is validated through processing synthetic and field data, underscoring its potential as a robust extraction technique.展开更多
The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calcula...The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.展开更多
Totally 26 provenance stands of 17-year-old Korean pine were selected for investigating wood properties and growth characters in Mao抏rshan Experimental Forest Farm of Northeast Forestry University in 1999. The anatom...Totally 26 provenance stands of 17-year-old Korean pine were selected for investigating wood properties and growth characters in Mao抏rshan Experimental Forest Farm of Northeast Forestry University in 1999. The anatomical property indexes, including tracheid length, tracheid diameter and wall-indiameter ratio, and the physical property indexes, such as growth ring width, late wood percentage and growth ring density, were measured for wood properties. Growth character indexes, including tree height and diameter at breast height, were also measured. The analytical results showed that there exited obviously dif-ference in wood property indexes between different provenances, which is suggested that wood properties are controlled by their genetic differences. The growth character indexes of Korean pines presented significant difference and they might also be controlled by their genetic differences. Most parameters of wood properties mainly varied in the direction of longitude, but the parameters of growth characters varied in the direction of latitude.展开更多
The vertical variation and storage of nitrogen in the depth of 0-150 cm of an aquic brown soil were studied under 14 years of four land use patterns, i.e., paddy field, maize field, fallow field and woodland in Shenya...The vertical variation and storage of nitrogen in the depth of 0-150 cm of an aquic brown soil were studied under 14 years of four land use patterns, i.e., paddy field, maize field, fallow field and woodland in Shenyang Experimental Station of Ecology, Chinese Academy of Sciences in November of 2003. The results showed that different land uses had different profile distributions of soil total nitrogen (STN), alkali N, ammonium (NH4+-N) and nitrate (NO3--N). The sequence of STN storage was woodland >maize field > fallow field > paddy field, while that of NO3--N content was maize field > paddy field > woodland > fallow field, suggesting the different root biomass and biological N cycling under various land uses. The STN storage in the depth of 0-100 cm of woodland averaged to 11.41 thm-1, being 1.65 and 1.25 times as much as that in paddy and maize fields, respec-tively, while there was no significant difference between maize and fallow fields. The comparatively higher amount of NO3--N in maize and paddy fields may be due to nitrogen fertilization and anthropogenic disturbance. Soil alkali N was significantly related with STN, and the correlation could be expressed by a linear regression model under each land use (R20.929, p<0.001). Such a correlation was slightly closer in nature (woodland and fallow field) than in agro ecosystems (paddy and maize fields). Heavy N fertilization induced an excess of crop need, and led to a comparatively higher amount of soil NO3--N in cultivated fields than in fallow field and woodland. It is suggested that agroforestry practices have the potential to make a significant contribution to both crop production and environment protection.展开更多
Using 3-year-old culms of 8 provenances of Bambusa chungii from Guangdong, Guangxi and Hainan Provinces, the indexes of wood properties, such as fiber dimensions and chemical composition were investigated and analyzed...Using 3-year-old culms of 8 provenances of Bambusa chungii from Guangdong, Guangxi and Hainan Provinces, the indexes of wood properties, such as fiber dimensions and chemical composition were investigated and analyzed by the methods of Analysis of variance and correlation coefficient to reveal the geographic genetic variation situation. The results showed that there are significant differences between fiber length, fibrin and 1% NaOH extraction contents of B. chungii from 8 provenances; moreover, the fiber length and fiber length/width ratio had a decreasing change pattern with geographic variation from the south to the north in altitude (from high to low in elevation). The heritabilities for fibrin, fiber length, 1% NaOH extractive, lignin and fiber length/width ratio were 0.7, 0.84, 0.54, 0.38 and 0.13, respectively. A significant negative correlation was found between 1% NaOH extraction, benzo-alcohol extraction contents and bamboo culm yield, whereas there was a significant positive correlation between fibrin contents and bamboo wood yield. Besides, a close correlation was detected between fiber dimensions indices and bamboo growth or bamboo wood yield. Finally, three provenances with high qualities and culm yield, i.e. Huaiji, Xinyi and Guilin, were selected as superior sources based on principal component analysis.展开更多
Bark samples of Magnolis officinalis were collected from a 7-year-old trial plantation with 13 provenances in Jingning County of Zhejiang Province on June 25, 2000. The contents of magnolol and honokiol of M. officina...Bark samples of Magnolis officinalis were collected from a 7-year-old trial plantation with 13 provenances in Jingning County of Zhejiang Province on June 25, 2000. The contents of magnolol and honokiol of M. officinalis were analyzed by the method of HPLC (High Performance Liquid Chromatogram). The results showed that such qualitative traits as the content of magnolol, content of honokiol, total content of key phenols, and the ratio of magnolo to honokiol differ significantly between the provenances. The provenances with a sharpened leaf tip from the western part of Hubei Province has a highest content of phenols, and that with a concave leaf tip from the Lushan Mountain has a lowest content of phenols. All these four qualitative traits were genetically controlled, with a heritability between 0.8342 and 0.9871 in terms of provenance. In addition, both longitudinal and latitudinal geographical variations could be found, with longitudinal variations being dominant. As a result, 3 superior provenances from Wufeng, Enshi and Hefeng of the western part of Hubei as well as 10 high-quality individuals were selected.展开更多
Tracheid characteristics ofPicea koraiensis from natural stand in Liangshui area and plantation in Mao'ershan area were studied. The results of variance analysis showed that the tracheid length, diameter, and thic...Tracheid characteristics ofPicea koraiensis from natural stand in Liangshui area and plantation in Mao'ershan area were studied. The results of variance analysis showed that the tracheid length, diameter, and thickness of tracheid wall were significant differences between the growth rings. All those characteristics tend to increase from heart-center to bark. In natural stand, it has positive correlation between the characteristics. In plantation, the tracheid length has positive correlation with the trachied diameter, while both the trachied length and the trachied diameter has negative correlation with the thickness of trachied wall. The tracheid length and diameter have no significant difference in growth between natural stand and plantations. The thickness of tracheid wall from the plantation is a little thicker than that from the natural stand before 15 years.展开更多
Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of diff...Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of different positions was observed,and the correlations between leaf NRA, leaf area and lamina mass per unit area (LMA) were also examined. The results showed that NRA in the leaf was significantly highest, compared with that in other organs such as roots, stems and leaves. In this experiment, the 10 leaves were selected from the apex to the base of the seedlings in order. The different NRA occurred obviously in leaves of different positions of C. acuminata seedlings from the apex to the base, and NRA was higher in the 4th-6th leaves.The diurnal change rhythm of leaf NRA showed a one peak curve, and maximum NRA value appeared at about midday (at 12:30 or so). No obvious correlations between NRA and leaf area or lamina mass per unit area were observed. This study offered scientific foundation for the further research on nitrogen metabolism of C. acuminata.展开更多
基金supported by the Shenzhen sustainable development project:KCXFZ 20201221173013036 and the National Natural Science Foundation of China(91746107).
文摘In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary random field in a small range,we give an entropy estimation and obtain the average entropy estimation formula in a certain bounded space region.It can be proven that the estimation of the average differential entropy converges to the theoretical value with a probability of 1.In addition,we also conducted numerical experiments for different parameters to verify the convergence result obtained in the theoretical proofs.
文摘This paper studies a strongly convergent inertial forward-backward-forward algorithm for the variational inequality problem in Hilbert spaces.In our convergence analysis,we do not assume the on-line rule of the inertial parameters and the iterates,which have been assumed by several authors whenever a strongly convergent algorithm with an inertial extrapolation step is proposed for a variational inequality problem.Consequently,our proof arguments are different from what is obtainable in the relevant literature.Finally,we give numerical tests to confirm the theoretical analysis and show that our proposed algorithm is superior to related ones in the literature.
基金supported by the National Key Research and Development Program of China(No.2020YFB1901900)the National Natural Science Foundation of China(Nos.U20B2011,12175138)the Shanghai Rising-Star Program。
文摘The heterogeneous variational nodal method(HVNM)has emerged as a potential approach for solving high-fidelity neutron transport problems.However,achieving accurate results with HVNM in large-scale problems using high-fidelity models has been challenging due to the prohibitive computational costs.This paper presents an efficient parallel algorithm tailored for HVNM based on the Message Passing Interface standard.The algorithm evenly distributes the response matrix sets among processors during the matrix formation process,thus enabling independent construction without communication.Once the formation tasks are completed,a collective operation merges and shares the matrix sets among the processors.For the solution process,the problem domain is decomposed into subdomains assigned to specific processors,and the red-black Gauss-Seidel iteration is employed within each subdomain to solve the response matrix equation.Point-to-point communication is conducted between adjacent subdomains to exchange data along the boundaries.The accuracy and efficiency of the parallel algorithm are verified using the KAIST and JRR-3 test cases.Numerical results obtained with multiple processors agree well with those obtained from Monte Carlo calculations.The parallelization of HVNM results in eigenvalue errors of 31 pcm/-90 pcm and fission rate RMS errors of 1.22%/0.66%,respectively,for the 3D KAIST problem and the 3D JRR-3 problem.In addition,the parallel algorithm significantly reduces computation time,with an efficiency of 68.51% using 36 processors in the KAIST problem and 77.14% using 144 processors in the JRR-3 problem.
基金supported by the National Natural Science Foundation of China (No.61971412)。
文摘Underwater monopulse space-time adaptive track-before-detect method,which combines space-time adaptive detector(STAD)and the track-before-detect algorithm based on dynamic programming(DP-TBD),denoted as STAD-DP-TBD,can effectively detect low-speed weak targets.However,due to the complexity and variability of the underwater environment,it is difficult to obtain sufficient secondary data,resulting in a serious decline in the detection and tracking performance,and leading to poor robustness of the algorithm.In this paper,based on the adaptive matched filter(AMF)test and the RAO test,underwater monopulse AMF-DP-TBD algorithm and RAO-DP-TBD algorithm which incorporate persymmetry and symmetric spectrum,denoted as PSAMF-DP-TBD and PS-RAO-DP-TBD,are proposed and compared with the AMF-DP-TBD algorithm and RAO-DP-TBD algorithm based on persymmetry array,denoted as P-AMF-DP-TBD and P-RAO-DP-TBD.The simulation results show that the four methods can work normally with sufficient secondary data and slightly insufficient secondary data,but when the secondary data is severely insufficient,the P-AMF-DP-TBD and P-RAO-DP-TBD algorithms has failed while the PSAMF-DP-TBD and PS-RAO-DP-TBD algorithms still have good detection and tracking capabilities.
基金supported by the National Natural Science Foundation of China(No.61971062)BUPT Excellent Ph.D.Students Foundation(CX2022153)。
文摘Video transmission requires considerable bandwidth,and current widely employed schemes prove inadequate when confronted with scenes featuring prominently.Motivated by the strides in talkinghead generative technology,the paper introduces a semantic transmission system tailored for talking-head videos.The system captures semantic information from talking-head video and faithfully reconstructs source video at the receiver,only one-shot reference frame and compact semantic features are required for the entire transmission.Specifically,we analyze video semantics in the pixel domain frame-by-frame and jointly process multi-frame semantic information to seamlessly incorporate spatial and temporal information.Variational modeling is utilized to evaluate the diversity of importance among group semantics,thereby guiding bandwidth resource allocation for semantics to enhance system efficiency.The whole endto-end system is modeled as an optimization problem and equivalent to acquiring optimal rate-distortion performance.We evaluate our system on both reference frame and video transmission,experimental results demonstrate that our system can improve the efficiency and robustness of communications.Compared to the classical approaches,our system can save over 90%of bandwidth when user perception is close.
基金the National Natural Science Foun-dation of China(Grant Nos.12105090 and 12175057).
文摘Leveraging the extraordinary phenomena of quantum superposition and quantum correlation,quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical computers.This paper tackles two pivotal challenges in the realm of quantum computing:firstly,the development of an effective encoding protocol for translating classical data into quantum states,a critical step for any quantum computation.Different encoding strategies can significantly influence quantum computer performance.Secondly,we address the need to counteract the inevitable noise that can hinder quantum acceleration.Our primary contribution is the introduction of a novel variational data encoding method,grounded in quantum regression algorithm models.By adapting the learning concept from machine learning,we render data encoding a learnable process.This allowed us to study the role of quantum correlation in data encoding.Through numerical simulations of various regression tasks,we demonstrate the efficacy of our variational data encoding,particularly post-learning from instructional data.Moreover,we delve into the role of quantum correlation in enhancing task performance,especially in noisy environments.Our findings underscore the critical role of quantum correlation in not only bolstering performance but also in mitigating noise interference,thus advancing the frontier of quantum computing.
基金supported in part by the National Science Foundation of China(NSFC)with grant no.62271514in part by the Science,Technology and Innovation Commission of Shenzhen Municipality with grant no.JCYJ20210324120002007 and ZDSYS20210623091807023in part by the State Key Laboratory of Public Big Data with grant no.PBD2023-01。
文摘Recently,deep learning-based semantic communication has garnered widespread attention,with numerous systems designed for transmitting diverse data sources,including text,image,and speech,etc.While efforts have been directed toward improving system performance,many studies have concentrated on enhancing the structure of the encoder and decoder.However,this often overlooks the resulting increase in model complexity,imposing additional storage and computational burdens on smart devices.Furthermore,existing work tends to prioritize explicit semantics,neglecting the potential of implicit semantics.This paper aims to easily and effectively enhance the receiver's decoding capability without modifying the encoder and decoder structures.We propose a novel semantic communication system with variational neural inference for text transmission.Specifically,we introduce a simple but effective variational neural inferer at the receiver to infer the latent semantic information within the received text.This information is then utilized to assist in the decoding process.The simulation results show a significant enhancement in system performance and improved robustness.
基金supported by Natural Science Foundation of China(no.72471087)Natural Science Foundation of Beijing Municipality(no.9242015).
文摘Zero-carbon parks have broad prospects in carbon neutralization.As an energy hub,hydrogen energy storage plays an important role in zero-carbon parks.However,the nonlinear characteristics of hydrogen energy storage systems(HESSs)have a significant impact on the system economy.Therefore,considering the variable working condition characteristics of HESSs,a hybrid operation method is proposed for HESS,to support the efficient and economic operation of zero-carbon parks,By analyzing the operating principle of a zero-carbon park with HESS,the system structure framework and variable condition linearization model of the equipment in HESS are established.Moreover,considering the energy output characteristics of hydrogen energy storage equipment under variable working conditions,a multimodule hybrid operation strategy is proposed for electrolytic and fuel cells,effectively meeting the thermoelectric load demand of zero-carbon parks in different scenarios.Finally,the economy of the proposed hybrid operation strategy was verified in typical scenarios,using a zero-carbon park embedded with a HESS.
基金supported by the National Natural Science Foundation of China under No. 52177217the Postdoctoral Innovative Talents Support Program under No. BX20240232。
文摘Cell-to-cell variations(CtCV) compromise the electrochemical performance of battery packs, yet the evolutional mechanism and quantitative impacts of CtCV on the pack's fast-charging performance remain unexplored. This knowledge gap is vital for the proliferation of electric vehicles. This study underlies the relationship between CtCV and charging performance by assessing the pack's charge speed, final electric quantity, and temperature consistency. Cell variations and pack status are depicted using 2D parameter diagrams, and an m PnS configured pack model is built upon a decomposed electrode cell model.Variations in three single electric parameters, i.e., capacity(Q), electric quantity(E), and internal resistance(R), and their dual interactions, i.e., E-Q and R-Q, are analyzed carefully. The results indicate that Q variations predominantly affect the final electric quantity of the pack, while R variations impact the charge speed most. With incremental variances in cell parameters, the pack's fast-charging capability first declines linearly and then deteriorates sharply as variations intensify. This research elucidates the correlations between pack charging capabilities and cell variations, providing essential insights for optimizing cell sorting and assembly, battery management design, and charging protocol development for battery packs.
基金supported by the National Natural Science Foundation of China(Grant Number 32201527)National Key R&D Program of China(Grant No.2023YFD2201004).
文摘Typhoons are becoming frequent and intense with ongoing climate change,threatening ecological security and healthy forest development in coastal areas.Eucalyptus of a predominant introduced species in southern China,faces significant growth challenges because of typhoon.Therefore,it is vital to investigate the variation of related traits and select superior breeding materials for genetic improvement.Variance,genetic parameter,and correlation analyses were carried out on wind damage indices and eight wood proper-ties in 88 families from 11 provenances of 10-year-old Euca-lyptus camaldulensis.The selection index equation was used for evaluating multiple traits and selecting superior prov-enances and family lines as future breeding material.The results show that all traits were highly significantly differ-ent at provenance and family levels,with the wind damage index having the highest coefficient of genetic variation.The heritability of each trait ranged from 0.48 to 0.87,with the wind damage index,lignin and hemicellulose contents,and microfibril angle having the highest heritabilities.The wind damage index had a positive genetic correlation with wood density,a negative correlation with lignin content,a negative phenotypic correlation and a negative genetic correlation with microfibril angle.Wind damage index and genetic progress in the selection of eight wood traits varied from 7.2%to 614.8%.Three provenances and 12 superior families were selected.The genetic gains of the wind damage index were 10.2%and 33.9%for provenances and families,and these may be starting material for genetic modification for wind resistance in eucalyptus and for their dissemination to typhoon-prone coastal areas of southern China.
基金supported by the Key Area Research and Development Program of Guangdong Province(2022B1111230001)theScience and Technology Foundation of Guangxi Zhuang Autonomous Region(Guike AD23026080)+1 种基金the National Natural Science Founda tion of China(No.42071065)Natural Science Foundation of US(No.2021898).
文摘Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.
基金supported by National Natural Science Foundation of China (42001305)Guangdong Basic and Applied Basic Research Foundation (2022A1515011459)+3 种基金GDAS'Special Project of Science and Technology Development (2020GDASYL-20200102001)Guangzhou Basic and Applied Basic Research Foundation (2023A04J1534) to Z.W.the US National Science Foundation (NSF) Macrosystems Biology and NEON-Enabled Science grant 1638720 to P.A.T.,and E.L.K.NSF Biology Integration Institute award ASCEND,DBI-2021898 to P.A.T.
文摘Characterizing foliar trait variation in sun and shade leaves can provide insights into inter-and intra-species resource use strategies and plant response to environmental change.However,datasets with records of multiple foliar traits from the same individual and including shade leaves are sparse,which limits our ability to investigate trait-trait,trait-environment relationships and trait coordination in both sun and shade leaves.We presented a comprehensive dataset of 15 foliar traits from sun and shade leaves sampled with leaf spectroscopy,including 424 individuals of 110 plant species from 19 sites across eastern North America.We investigated trait variation,covariation,scaling relationships with leaf mass,and the effects of environment,canopy position,and taxonomy on trait expression.Generally,sun leaves had higher leaf mass per area,nonstructural carbohydrates and total phenolics,lower mass-based chlorophyll a+b,carotenoids,phosphorus,and potassium,but exhibited species-specific characteristics.Covariation between sun and shade leaf traits,and trait-environment relationships were overall consistent across species.The main dimensions of foliar trait variation in seed plants were revealed including leaf economics traits,photosynthetic pigments,defense,and structural traits.Taxonomy and canopy position collectively explained most of the foliar trait variation.This study highlights the importance of including intra-individual and intra-specific trait variation to improve our understanding of ecosystem functions.Our findings have implications for efficient field sampling,and trait mapping with remote sensing.
基金supported by the National Natural Science Foundation of China (grant No. 42204126, 42174145, 42104132)Laoshan National Laboratory Science and Technology Innovation Project (grant No. LSKJ202203407)。
文摘Remote reflection waves, essential for acquiring high-resolution images of geological structures beyond boreholes, often suffer contamination from strong direct mode waves propagating along the borehole.Consequently, the extraction of weak reflected waves becomes pivotal for optimizing migration image quality. This paper introduces a novel approach to extracting reflected waves by sequentially operating in the spatial frequency and curvelet domains. Using variation mode decomposition(VMD), single-channel spatial domain signals within the common offset gather are iteratively decomposed into high-wavenumber and low-wavenumber intrinsic mode functions(IMFs). The low-wavenumber IMF is then subtracted from the overall waveform to attenuate direct mode waves. Subsequently, the curvelet transform is employed to segregate upgoing and downgoing reflected waves within the filtered curvelet domain. As a result, direct mode waves are substantially suppressed, while the integrity of reflected waves is fully preserved. The efficacy of this approach is validated through processing synthetic and field data, underscoring its potential as a robust extraction technique.
基金supported by the National Natural Science Foundation of China(52372310)the State Key Laboratory of Advanced Rail Autonomous Operation(RAO2023ZZ001)+1 种基金the Fundamental Research Funds for the Central Universities(2022JBQY001)Beijing Laboratory of Urban Rail Transit.
文摘The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.
文摘Totally 26 provenance stands of 17-year-old Korean pine were selected for investigating wood properties and growth characters in Mao抏rshan Experimental Forest Farm of Northeast Forestry University in 1999. The anatomical property indexes, including tracheid length, tracheid diameter and wall-indiameter ratio, and the physical property indexes, such as growth ring width, late wood percentage and growth ring density, were measured for wood properties. Growth character indexes, including tree height and diameter at breast height, were also measured. The analytical results showed that there exited obviously dif-ference in wood property indexes between different provenances, which is suggested that wood properties are controlled by their genetic differences. The growth character indexes of Korean pines presented significant difference and they might also be controlled by their genetic differences. Most parameters of wood properties mainly varied in the direction of longitude, but the parameters of growth characters varied in the direction of latitude.
文摘The vertical variation and storage of nitrogen in the depth of 0-150 cm of an aquic brown soil were studied under 14 years of four land use patterns, i.e., paddy field, maize field, fallow field and woodland in Shenyang Experimental Station of Ecology, Chinese Academy of Sciences in November of 2003. The results showed that different land uses had different profile distributions of soil total nitrogen (STN), alkali N, ammonium (NH4+-N) and nitrate (NO3--N). The sequence of STN storage was woodland >maize field > fallow field > paddy field, while that of NO3--N content was maize field > paddy field > woodland > fallow field, suggesting the different root biomass and biological N cycling under various land uses. The STN storage in the depth of 0-100 cm of woodland averaged to 11.41 thm-1, being 1.65 and 1.25 times as much as that in paddy and maize fields, respec-tively, while there was no significant difference between maize and fallow fields. The comparatively higher amount of NO3--N in maize and paddy fields may be due to nitrogen fertilization and anthropogenic disturbance. Soil alkali N was significantly related with STN, and the correlation could be expressed by a linear regression model under each land use (R20.929, p<0.001). Such a correlation was slightly closer in nature (woodland and fallow field) than in agro ecosystems (paddy and maize fields). Heavy N fertilization induced an excess of crop need, and led to a comparatively higher amount of soil NO3--N in cultivated fields than in fallow field and woodland. It is suggested that agroforestry practices have the potential to make a significant contribution to both crop production and environment protection.
基金funded by both of the Interna-tional Tropical Timber Organization (ITTO), grant No. PD10/00. REV.2 (I,F)the National‘Tenth Five-year’Key Program of China, grant No. 2004BA506B0103
文摘Using 3-year-old culms of 8 provenances of Bambusa chungii from Guangdong, Guangxi and Hainan Provinces, the indexes of wood properties, such as fiber dimensions and chemical composition were investigated and analyzed by the methods of Analysis of variance and correlation coefficient to reveal the geographic genetic variation situation. The results showed that there are significant differences between fiber length, fibrin and 1% NaOH extraction contents of B. chungii from 8 provenances; moreover, the fiber length and fiber length/width ratio had a decreasing change pattern with geographic variation from the south to the north in altitude (from high to low in elevation). The heritabilities for fibrin, fiber length, 1% NaOH extractive, lignin and fiber length/width ratio were 0.7, 0.84, 0.54, 0.38 and 0.13, respectively. A significant negative correlation was found between 1% NaOH extraction, benzo-alcohol extraction contents and bamboo culm yield, whereas there was a significant positive correlation between fibrin contents and bamboo wood yield. Besides, a close correlation was detected between fiber dimensions indices and bamboo growth or bamboo wood yield. Finally, three provenances with high qualities and culm yield, i.e. Huaiji, Xinyi and Guilin, were selected as superior sources based on principal component analysis.
文摘Bark samples of Magnolis officinalis were collected from a 7-year-old trial plantation with 13 provenances in Jingning County of Zhejiang Province on June 25, 2000. The contents of magnolol and honokiol of M. officinalis were analyzed by the method of HPLC (High Performance Liquid Chromatogram). The results showed that such qualitative traits as the content of magnolol, content of honokiol, total content of key phenols, and the ratio of magnolo to honokiol differ significantly between the provenances. The provenances with a sharpened leaf tip from the western part of Hubei Province has a highest content of phenols, and that with a concave leaf tip from the Lushan Mountain has a lowest content of phenols. All these four qualitative traits were genetically controlled, with a heritability between 0.8342 and 0.9871 in terms of provenance. In addition, both longitudinal and latitudinal geographical variations could be found, with longitudinal variations being dominant. As a result, 3 superior provenances from Wufeng, Enshi and Hefeng of the western part of Hubei as well as 10 high-quality individuals were selected.
基金part of State 9th Five-Year Plan project of "Early Mensuration of Picea koraiensis (nakai)".
文摘Tracheid characteristics ofPicea koraiensis from natural stand in Liangshui area and plantation in Mao'ershan area were studied. The results of variance analysis showed that the tracheid length, diameter, and thickness of tracheid wall were significant differences between the growth rings. All those characteristics tend to increase from heart-center to bark. In natural stand, it has positive correlation between the characteristics. In plantation, the tracheid length has positive correlation with the trachied diameter, while both the trachied length and the trachied diameter has negative correlation with the thickness of trachied wall. The tracheid length and diameter have no significant difference in growth between natural stand and plantations. The thickness of tracheid wall from the plantation is a little thicker than that from the natural stand before 15 years.
文摘Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of different positions was observed,and the correlations between leaf NRA, leaf area and lamina mass per unit area (LMA) were also examined. The results showed that NRA in the leaf was significantly highest, compared with that in other organs such as roots, stems and leaves. In this experiment, the 10 leaves were selected from the apex to the base of the seedlings in order. The different NRA occurred obviously in leaves of different positions of C. acuminata seedlings from the apex to the base, and NRA was higher in the 4th-6th leaves.The diurnal change rhythm of leaf NRA showed a one peak curve, and maximum NRA value appeared at about midday (at 12:30 or so). No obvious correlations between NRA and leaf area or lamina mass per unit area were observed. This study offered scientific foundation for the further research on nitrogen metabolism of C. acuminata.
