We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the ...We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.展开更多
To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produce...To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.展开更多
In modern ZnO varistors,traditional aging mechanisms based on increased power consumption are no longer relevant due to reduced power consumption during DC aging.Prolonged exposure to both AC and DC voltages results i...In modern ZnO varistors,traditional aging mechanisms based on increased power consumption are no longer relevant due to reduced power consumption during DC aging.Prolonged exposure to both AC and DC voltages results in increased leakage current,decreased breakdown voltage,and lower nonlinearity,ultimately compromising their protective performance.To investigate the evolution in electrical properties during DC aging,this work developed a finite element model based on Voronoi networks and conducted accelerated aging tests on commercial varistors.Throughout the aging process,current-voltage characteristics and Schottky barrier parameters were measured and analyzed.The results indicate that when subjected to constant voltage,current flows through regions with larger grain sizes,forming discharge channels.As aging progresses,the current focus increases on these channels,leading to a decline in the varistor’s overall performance.Furthermore,analysis of the Schottky barrier parameters shows that the changes in electrical performance during aging are non-monotonic.These findings offer theoretical support for understanding the aging mechanisms and condition assessment of modern stable ZnO varistors.展开更多
ne way to speed up the execution of sequential programs is to divide them into concurrent segments and execute such segments in a parallel manner over a distributed computing environment. We argue that the execution s...ne way to speed up the execution of sequential programs is to divide them into concurrent segments and execute such segments in a parallel manner over a distributed computing environment. We argue that the execution speedup primarily depends on the concurrency degree between the identified segments as well as communication overhead between the segments. To guar-antee the best speedup, we have to obtain the maximum possible concurrency degree between the identified segments, taking communication overhead into consideration. Existing code distributor and multi-threading approaches do not fulfill such re-quirements;hence, they cannot provide expected distributability gains in advance. To overcome such limitations, we propose a novel approach for verifying the distributability of sequential object-oriented programs. The proposed approach enables users to see the maximum speedup gains before the actual distributability implementations, as it computes an objective function which is used to measure different distribution values from the same program, taking into consideration both remote and sequential calls. Experimental results showed that the proposed approach successfully determines the distributability of different real-life software applications compared with their real-life sequential and distributed implementations.展开更多
With the start of the new year,Wen Congxiang,managing director of Ningbo Nuoding,a company specialising in the recycling of end-of-life vehicles,has been constantly on the move.Much of his time is spent coordinating w...With the start of the new year,Wen Congxiang,managing director of Ningbo Nuoding,a company specialising in the recycling of end-of-life vehicles,has been constantly on the move.Much of his time is spent coordinating with vehicle collection firms,electric bicycle manufacturers and recycled materials distributors,as he works to build partnerships focused on the targeted collection and distribution of recycled products.展开更多
Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressur...Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressure as the shock wave propagates initially to the rear of the projectile.The shock wave that induces a phase-transition is commonly referred to as a macroscopic phase-transition wave,whereas the interface that separates the distinct phases is referred to as macroscopic phase-boundary.The contact interface between the spherical projectile and the thin plate,characterized by its curved surface,plays a significant role in the nonlinear propagation and evolution of wave systems.The pressure distribution along the central axis of a spherical projectile is derived in accordance with the linear decay law observed for axial pressure.On this basis,a quadratic function is employed to characterize the trend of changes in wave front pressure,thereby facilitating the establishment of a model for wave front pressure distribution.Using the phase-transition pressure criterion for materials,the wave front phase evolution process is derived,and the macroscopic phase-boundary is determined.Based on the geometric propagation model(GPM)and the pressure distribution of the wave front,a phase geometric propagation model(PGPM)is proposed.The phase distribution of a spherical projectile impacting a thin plate is obtained by theoretical methods.The accuracy of the PGPM is subsequently validated through a comparison of its results with those obtained from numerical simulations.展开更多
Distributed learning is a well-established method for estimation tasks over extensively distributed datasets.However,non-randomly stored data can introduce bias into local parameter estimates,leading to significant pe...Distributed learning is a well-established method for estimation tasks over extensively distributed datasets.However,non-randomly stored data can introduce bias into local parameter estimates,leading to significant performance degradation in classical distributed algorithms.In this paper,the authors propose a novel Distributed Quasi-Newton Pilot(DQNP)method for distributed learning with non-randomly distributed data.The proposed approach accommodates both randomly and non-randomly distributed data settings and imposes no constraints on the uniformity of local sample sizes.Additionally,it avoids the need to transfer the Hessian matrix or compute its inversion,thereby greatly reducing computational and communication complexity.The authors theoretically demonstrate that the resulting estimator achieves statistical efficiency under mild conditions.Extensive numerical experiments on synthetic and real-world data validate the theoretical findings and illustrate the effectiveness of the proposed method.展开更多
In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic res...In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin,with their superior reservoir properties playing a crucial role in natural gas formation.However,due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities,predicting volcanic facies distribution and favorable reservoirs remains highly challenging.This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift.By integrating drilling and petrophysical data with well-seismic analysis techniques,a seismic identification model for volcanic reservoirs has been established.The findings reveal that different facies exhibit distinct seismic response characteristics.Andesite,rhyolite,volcanic breccia,and volcanic clastic rocks show variability in amplitude,frequency,and continuity.Using structural-guided filtering,high-resolution coherence analysis,and 3D body carving techniques,the locations of volcanic craters and eruption centers were successfully identified,further clarifying the distribution patterns of volcanic facies.By combining multi-attribute clustering analysis and seismic attribute extraction,a volcanic facies zone distribution map was generated,and favorable exploration directions for volcanic reservoirs were proposed.The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.展开更多
Federated learning often experiences slow and unstable convergence due to edge-side data heterogeneity.This problem becomes more severe when edge participation rate is low,as the information collected from different e...Federated learning often experiences slow and unstable convergence due to edge-side data heterogeneity.This problem becomes more severe when edge participation rate is low,as the information collected from different edge devices varies significantly.As a result,communication overhead increases,which further slows down the convergence process.To address this challenge,we propose a simple yet effective federated learning framework that improves consistency among edge devices.The core idea is clusters the lookahead gradients collected from edge devices on the cloud server to obtain personalized momentum for steering local updates.In parallel,a global momentum is applied during model aggregation,enabling faster convergence while preserving personalization.This strategy enables efficient propagation of the estimated global update direction to all participating edge devices and maintains alignment in local training,without introducing extra memory or communication overhead.We conduct extensive experiments on benchmark datasets such as Cifar100 and Tiny-ImageNet.The results confirm the effectiveness of our framework.On CIFAR-100,our method reaches 55%accuracy with 37 fewer rounds and achieves a competitive final accuracy of 65.46%.Even under extreme non-IID scenarios,it delivers significant improvements in both accuracy and communication efficiency.The implementation is publicly available at https://github.com/sjmp525/CollaborativeComputing/tree/FedCCM(accessed on 20 October 2025).展开更多
Thermal storage electric heating(TSEH),as a prevalent variable load resource,offers significant potential for enhancing system flexibility when aggregated into a cluster.To address the uncertainties of renewable energ...Thermal storage electric heating(TSEH),as a prevalent variable load resource,offers significant potential for enhancing system flexibility when aggregated into a cluster.To address the uncertainties of renewable energy and load forecasting in active distribution networks(ADN),this paper proposes a multi-timescale coordinated optimal dispatch strategy that incorporates TSEH clusters.It utilizes the thermal storage characteristics and short-term regulation capabilities of TSEH,along with the rapid and gradual response characteristics of resources in active distribution grids,to develop a coordinated optimization dispatch mechanism for day-ahead,intraday,and real-time stages.It provides a coordinated optimized dispatch technique across several timescales for active distribution grids,taking into account the integration of TSEH clusters.The proposed method is validated on a modified IEEE 33-node system.Simulation results demonstrate that the participation of TSEH in collaborative optimization significantly reduces the total system operating cost by 8.71%compared to the scenario without TSEH.This cost reduction is attributed to a 10.84%decrease in interaction costs with the main grid and a 47.41%reduction in network loss costs,validating effective peak shaving and valley filling.The multi-timescale framework further enhances economic efficiency,with overall operating costs progressively decreasing by 3.91%(intraday)and 4.59%(real-time),and interaction costs further reduced by 5.34%and 9.25%,respectively.Moreover,the approach enhances system stability by effectively suppressing node voltage fluctuations and ensuring all voltages remain within safe operating limits during real-time operation.Therefore,the proposed approach achieves rational coordination of diverse resources,significantly improving the economic efficiency and stability of ADNs.展开更多
Dear Editor,This letter addresses the challenge of achieving robust global coordination in multi-agent systems(MASs)subject to heterogeneous actuator saturation and additive input disturbances.We develop a novel distr...Dear Editor,This letter addresses the challenge of achieving robust global coordination in multi-agent systems(MASs)subject to heterogeneous actuator saturation and additive input disturbances.We develop a novel distributed control framework that strategically integrates a redesigned saturation function to handle the nonlinear actuator constraint and a high-gain feedback mechanism for effective disturbance rejection.展开更多
Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of soci...Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of social concern.Based on observation data concerning low-visibility phenomena derived from 105 national meteorological stations in Xinjiang,China over the past 20 years,we systematically analyzed the differences between manual and instrument observations for six types of low-visibility phenomena,with a focus on exploring their spatiotemporal distribution characteristics using instrument data.The results revealed that low-visibility phenomena were dominated by fog-and haze-related events(mist,fog,and haze)in northern Xinjiang and dust-related events(dust storms,blowing sand,and floating dust)in southern Xinjiang,with transitional characteristics observed in eastern Xinjiang.Compared with manual observations,the instrument measurements significantly improved the fine-scale low-visibility phenomenon identification process.On the basis of the instrument observation data,spatial-dimension analysis results indicated that low-visibility phenomena in Xinjiang were significantly influenced by terrain factors.Constrained by the Tianshan Mountains,haze-like phenomena formed a core agglomeration area in northern Xinjiang,whereas dust-and sand-related phenomena radiated outward,with the Taklimakan Desert at the center.Moreover,the gripping effect of the terrain promoted dust transmission along low-altitude channels.Temporally,fog-and haze-related phenomena occurred mainly during autumn and winter,and the proportion of these events decreased from 76.7%to 55.1%.The fog-and haze-related phenomena demonstrated a U-shaped rebound trend,while the proportion of mist phenomena decreased by 34.2%.Dust storms occurred during spring,accounting for 23.3%to 44.9%of all storms.Instrument measurement technology has the advantages of high spatial and temporal resolutions and multiparameter coordination but provides a limited dust-haze mixed-pollution identification capacity.This study provides crucial reference data for enhancing the understanding of low-visibility events in Xinjiang and the potential responses while improving the accuracy of pollution source tracking and meteorological process diagnosis tasks.展开更多
With the rapid development of generative artificial intelligence(GenAI),the task of story visualization,which transforms natural language narratives into coherent and consistent image sequences,has attracted growing r...With the rapid development of generative artificial intelligence(GenAI),the task of story visualization,which transforms natural language narratives into coherent and consistent image sequences,has attracted growing research attention.However,existing methods still face limitations in balancing multi-frame character consistency and generation efficiency,which restricts their feasibility for large-scale practical applications.To address this issue,this study proposes a modular cloud-based distributed system built on Stable Diffusion.By separating the character generation and story generation processes,and integratingmulti-feature control techniques,a cachingmechanism,and an asynchronous task queue architecture,the system enhances generation efficiency and scalability.The experimental design includes both automated and human evaluations of character consistency,performance testing,and multinode simulation.The results show that the proposed system outperforms the baseline model StoryGen in both CLIP-I and human evaluation metrics.In terms of performance,under the experimental environment of this study,dual-node deployment reduces average waiting time by approximately 19%,while the four-node simulation further reduces it by up to 65%.Overall,this study demonstrates the advantages of cloud-distributed GenAI in maintaining character consistency and reducing generation latency,highlighting its potential value inmulti-user collaborative story visualization applications.展开更多
As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpi...As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpine plant distribution and their profound impact on fragile ecosystems have become a focus of ecological research and conservation efforts,with increasing urgency.Meconopsis,a typical representative of Chinese alpine plants,exhibits diverse adaptability,making it an ideal model for studying how alpine species respond to extreme environmental changes.A lack of comprehensive genus-level analyses may hinder the development of long-term conservation and management strategies.Given the genus's ecological importance,vulnerability,and the risk of trait homogenization in genus-level modeling,there is an urgent need to assess its future distribution patterns,migration trends,and adaptive mechanisms based on habitat classification.In this study,we employed the Maxent model,integrating multidimensional environmental variables,to develop genus-level models and representative habitat-based models(forest,meadows,and periglacial).Results indicate a northwestward expansion and southeastward contraction of suitable habitats under future climate scenarios,with migration patterns in latitude and elevation showing stage-specific characteristics.Key environmental factors varied across models but were mostly associated with seasonal growth traits and microhabitat conditions,highlighting both the universal ecological requirements and niche differentiation within Meconopsis.Based on these findings,we propose a dynamic conservation strategy framework informed by stage-specific responses and habitat differences.Future efforts should focus on incorporating alpine-specific environmental variables and optimizing specimen collection strategies to enhance model performance and support landscape planning and biodiversity conservation.展开更多
Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges...Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).展开更多
Objectives This study aimed to explore the lagged and cumulative effects of risk factors on disability in older adults using distributed lag non-linear models(DLNMs).Methods We utilized data from the China Health and ...Objectives This study aimed to explore the lagged and cumulative effects of risk factors on disability in older adults using distributed lag non-linear models(DLNMs).Methods We utilized data from the China Health and Retirement Longitudinal Study(CHARLS).After feature selection via Elastic Net Regularization,we applied DLNMs to evaluate the lagged effects of risk factors.Disability was defined as the presence of any difficulties in basic activities of daily living(BADL).The cumulative relative risk(CRR)was calculated by summing the lag-specific risk estimates,representing the cumulative disability risk over the specified lag period.Effect modifications and sensitivity analyses were also performed.Results This study included a total of 2,318 participants.Early-phase lag factors,such as the difficulty in stooping(CRR=3.58;95%CI:2.31-5.55;P<0.001)and walking(CRR=2.77;95%CI:1.39-5.55;P<0.001),exerted the strongest effects immediately upon occurrence.Mid-phase lag factors,such as arthritis(CRR=1.51;95%CI:1.10-2.06;P=0.001),showed a resurgence in disability risk within 2-3 years.Late-phase lag factors,including depressive symptoms(CRR=2.38;95%CI:1.30-4.35;P<0.001)and elevated systolic blood pressure(CRR=1.64;95%CI:1.06-2.79;P=0.02),exhibited significant long-term cumulative risks.Conversely,grip strength(CRR=0.80;95%CI:0.54-0.95;P=0.02)and social participation(CRR=0.89;95%CI:0.73-0.99;P=0.04)were significant protective factors.Conclusions The findings underscore the importance of tailored interventions that account for various lag characteristics of different factors to effectively mitigate disability risk.Future studies should explore the underlying biological and sociological mechanisms of these lagged effects,identify intervention strategies that target risk factors with different lagged patterns,and evaluate their effectiveness.展开更多
The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very lon...The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.展开更多
Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly im...Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly impact evaluation results.To address this issue,this paper proposes a possibilistic approach to evaluate PV hosting capacity(PVHC).First,possibility distribution is used to model load demand in order to reflect uncertainties associated with human factor,whereas the interval model is applied to deal with uncertainties of PV outputs.Second,a voltage deterioration index is proposed considering overvoltage risk of entire system on time scale.After that,possibilistic PVHC evaluation method based on this index is proposed.A 6-bus system is used to illustrate advantages of the proposed method,followed by a discussion of role of PVHC possibility distribution in actual decision-making of utilities.Moreover,sensitivity of simulation parameters is analyzed to reduce computational burden.Finally,the proposed method is tested on the IEEE 123-bus DN to validate adaptability to a larger system and to analyze impact of PVHC results against different acceptable values set by utilities.展开更多
In the era of massive data,the study of distributed data is a significant topic.Model averaging can be effectively applied to distributed data by combining information from all machines.For linear models,the model ave...In the era of massive data,the study of distributed data is a significant topic.Model averaging can be effectively applied to distributed data by combining information from all machines.For linear models,the model averaging approach has been developed in the context of distributed data.However,further investigation is needed for more complex models.In this paper,the authors propose a distributed optimal model averaging approach based on multivariate additive models,which approximates unknown functions using B-splines allowing each machine to have a different smoothing degree.To utilize the information from the covariance matrix of dependent errors in multivariate multiple regressions,the authors use the Mahalanobis distance to construct a Mallows-type weight choice criterion.The criterion can be computed by transmitting information between the local machines and the center machine in two steps.The authors demonstrate the asymptotic optimality of the proposed model averaging estimator when the covariates are subject to uncertainty,and obtain the convergence rate of the weight vector to the theoretically optimal weights.The results remain novel even for additive models with a single response variable.The numerical examples show that the proposed method yields good performance.展开更多
Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angl...Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.展开更多
基金supported by Xinjiang Normal University Outstanding Young Teacher Research Launch Fund Project(Grant No.XJNU202116)。
文摘We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.
基金National Natural Science Foundation of China(12125509,11961141003,12275361,U2267205,12175152,12175121)National Key Research and Development Project(2022YFA1602301)Continuous-support Basic Scientific Research Project。
文摘To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.
文摘In modern ZnO varistors,traditional aging mechanisms based on increased power consumption are no longer relevant due to reduced power consumption during DC aging.Prolonged exposure to both AC and DC voltages results in increased leakage current,decreased breakdown voltage,and lower nonlinearity,ultimately compromising their protective performance.To investigate the evolution in electrical properties during DC aging,this work developed a finite element model based on Voronoi networks and conducted accelerated aging tests on commercial varistors.Throughout the aging process,current-voltage characteristics and Schottky barrier parameters were measured and analyzed.The results indicate that when subjected to constant voltage,current flows through regions with larger grain sizes,forming discharge channels.As aging progresses,the current focus increases on these channels,leading to a decline in the varistor’s overall performance.Furthermore,analysis of the Schottky barrier parameters shows that the changes in electrical performance during aging are non-monotonic.These findings offer theoretical support for understanding the aging mechanisms and condition assessment of modern stable ZnO varistors.
文摘ne way to speed up the execution of sequential programs is to divide them into concurrent segments and execute such segments in a parallel manner over a distributed computing environment. We argue that the execution speedup primarily depends on the concurrency degree between the identified segments as well as communication overhead between the segments. To guar-antee the best speedup, we have to obtain the maximum possible concurrency degree between the identified segments, taking communication overhead into consideration. Existing code distributor and multi-threading approaches do not fulfill such re-quirements;hence, they cannot provide expected distributability gains in advance. To overcome such limitations, we propose a novel approach for verifying the distributability of sequential object-oriented programs. The proposed approach enables users to see the maximum speedup gains before the actual distributability implementations, as it computes an objective function which is used to measure different distribution values from the same program, taking into consideration both remote and sequential calls. Experimental results showed that the proposed approach successfully determines the distributability of different real-life software applications compared with their real-life sequential and distributed implementations.
文摘With the start of the new year,Wen Congxiang,managing director of Ningbo Nuoding,a company specialising in the recycling of end-of-life vehicles,has been constantly on the move.Much of his time is spent coordinating with vehicle collection firms,electric bicycle manufacturers and recycled materials distributors,as he works to build partnerships focused on the targeted collection and distribution of recycled products.
基金supported by National Natural Science Foundation of China(Nos.12432018,12372346)the Innovative Research Groups of the National Natural Science Foundation of China(No.12221002)National Natural Science Foundation of China(No.12302493)。
文摘Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressure as the shock wave propagates initially to the rear of the projectile.The shock wave that induces a phase-transition is commonly referred to as a macroscopic phase-transition wave,whereas the interface that separates the distinct phases is referred to as macroscopic phase-boundary.The contact interface between the spherical projectile and the thin plate,characterized by its curved surface,plays a significant role in the nonlinear propagation and evolution of wave systems.The pressure distribution along the central axis of a spherical projectile is derived in accordance with the linear decay law observed for axial pressure.On this basis,a quadratic function is employed to characterize the trend of changes in wave front pressure,thereby facilitating the establishment of a model for wave front pressure distribution.Using the phase-transition pressure criterion for materials,the wave front phase evolution process is derived,and the macroscopic phase-boundary is determined.Based on the geometric propagation model(GPM)and the pressure distribution of the wave front,a phase geometric propagation model(PGPM)is proposed.The phase distribution of a spherical projectile impacting a thin plate is obtained by theoretical methods.The accuracy of the PGPM is subsequently validated through a comparison of its results with those obtained from numerical simulations.
基金supported by the National Natural Science Foundation of China under Grant No.12271034the Open Fund Project of Key Laboratory of Market Regulation under Grant No.2023SYSKF02003。
文摘Distributed learning is a well-established method for estimation tasks over extensively distributed datasets.However,non-randomly stored data can introduce bias into local parameter estimates,leading to significant performance degradation in classical distributed algorithms.In this paper,the authors propose a novel Distributed Quasi-Newton Pilot(DQNP)method for distributed learning with non-randomly distributed data.The proposed approach accommodates both randomly and non-randomly distributed data settings and imposes no constraints on the uniformity of local sample sizes.Additionally,it avoids the need to transfer the Hessian matrix or compute its inversion,thereby greatly reducing computational and communication complexity.The authors theoretically demonstrate that the resulting estimator achieves statistical efficiency under mild conditions.Extensive numerical experiments on synthetic and real-world data validate the theoretical findings and illustrate the effectiveness of the proposed method.
文摘In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin,with their superior reservoir properties playing a crucial role in natural gas formation.However,due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities,predicting volcanic facies distribution and favorable reservoirs remains highly challenging.This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift.By integrating drilling and petrophysical data with well-seismic analysis techniques,a seismic identification model for volcanic reservoirs has been established.The findings reveal that different facies exhibit distinct seismic response characteristics.Andesite,rhyolite,volcanic breccia,and volcanic clastic rocks show variability in amplitude,frequency,and continuity.Using structural-guided filtering,high-resolution coherence analysis,and 3D body carving techniques,the locations of volcanic craters and eruption centers were successfully identified,further clarifying the distribution patterns of volcanic facies.By combining multi-attribute clustering analysis and seismic attribute extraction,a volcanic facies zone distribution map was generated,and favorable exploration directions for volcanic reservoirs were proposed.The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.
基金supported by the National Natural Science Foundation of China(62462040)the Yunnan Fundamental Research Projects(202501AT070345)the Major Science and Technology Projects in Yunnan Province(202202AD080013).
文摘Federated learning often experiences slow and unstable convergence due to edge-side data heterogeneity.This problem becomes more severe when edge participation rate is low,as the information collected from different edge devices varies significantly.As a result,communication overhead increases,which further slows down the convergence process.To address this challenge,we propose a simple yet effective federated learning framework that improves consistency among edge devices.The core idea is clusters the lookahead gradients collected from edge devices on the cloud server to obtain personalized momentum for steering local updates.In parallel,a global momentum is applied during model aggregation,enabling faster convergence while preserving personalization.This strategy enables efficient propagation of the estimated global update direction to all participating edge devices and maintains alignment in local training,without introducing extra memory or communication overhead.We conduct extensive experiments on benchmark datasets such as Cifar100 and Tiny-ImageNet.The results confirm the effectiveness of our framework.On CIFAR-100,our method reaches 55%accuracy with 37 fewer rounds and achieves a competitive final accuracy of 65.46%.Even under extreme non-IID scenarios,it delivers significant improvements in both accuracy and communication efficiency.The implementation is publicly available at https://github.com/sjmp525/CollaborativeComputing/tree/FedCCM(accessed on 20 October 2025).
基金supported by Integrated Distribution Network Planning and Operational Enhancement Using Flexibility Domains Under Deep Human-Vehicle-Charger-Road-Grid Coupling(U22B20105).
文摘Thermal storage electric heating(TSEH),as a prevalent variable load resource,offers significant potential for enhancing system flexibility when aggregated into a cluster.To address the uncertainties of renewable energy and load forecasting in active distribution networks(ADN),this paper proposes a multi-timescale coordinated optimal dispatch strategy that incorporates TSEH clusters.It utilizes the thermal storage characteristics and short-term regulation capabilities of TSEH,along with the rapid and gradual response characteristics of resources in active distribution grids,to develop a coordinated optimization dispatch mechanism for day-ahead,intraday,and real-time stages.It provides a coordinated optimized dispatch technique across several timescales for active distribution grids,taking into account the integration of TSEH clusters.The proposed method is validated on a modified IEEE 33-node system.Simulation results demonstrate that the participation of TSEH in collaborative optimization significantly reduces the total system operating cost by 8.71%compared to the scenario without TSEH.This cost reduction is attributed to a 10.84%decrease in interaction costs with the main grid and a 47.41%reduction in network loss costs,validating effective peak shaving and valley filling.The multi-timescale framework further enhances economic efficiency,with overall operating costs progressively decreasing by 3.91%(intraday)and 4.59%(real-time),and interaction costs further reduced by 5.34%and 9.25%,respectively.Moreover,the approach enhances system stability by effectively suppressing node voltage fluctuations and ensuring all voltages remain within safe operating limits during real-time operation.Therefore,the proposed approach achieves rational coordination of diverse resources,significantly improving the economic efficiency and stability of ADNs.
基金supported in part by the National Natural Science Foundation of China(62522313,62473207,U25A20301)the Fundamental Research Funds for the Central Universities(2024SMECP03)。
文摘Dear Editor,This letter addresses the challenge of achieving robust global coordination in multi-agent systems(MASs)subject to heterogeneous actuator saturation and additive input disturbances.We develop a novel distributed control framework that strategically integrates a redesigned saturation function to handle the nonlinear actuator constraint and a high-gain feedback mechanism for effective disturbance rejection.
基金supported by the Central Government Guidance Funds for Local Science and Technology Development Program(grant no.ZYYD2025ZY21)the Science and Technology Plan Project of the Xinjiang Production and Construction Corps(2023AB036)+1 种基金the Xinjiang Meteorological Bureau High-Level Key Talent Programthe Natural Science Foundation of the Xinjiang Uygur Autonomous Region(2023D01A17 and 2025D01A109).
文摘Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of social concern.Based on observation data concerning low-visibility phenomena derived from 105 national meteorological stations in Xinjiang,China over the past 20 years,we systematically analyzed the differences between manual and instrument observations for six types of low-visibility phenomena,with a focus on exploring their spatiotemporal distribution characteristics using instrument data.The results revealed that low-visibility phenomena were dominated by fog-and haze-related events(mist,fog,and haze)in northern Xinjiang and dust-related events(dust storms,blowing sand,and floating dust)in southern Xinjiang,with transitional characteristics observed in eastern Xinjiang.Compared with manual observations,the instrument measurements significantly improved the fine-scale low-visibility phenomenon identification process.On the basis of the instrument observation data,spatial-dimension analysis results indicated that low-visibility phenomena in Xinjiang were significantly influenced by terrain factors.Constrained by the Tianshan Mountains,haze-like phenomena formed a core agglomeration area in northern Xinjiang,whereas dust-and sand-related phenomena radiated outward,with the Taklimakan Desert at the center.Moreover,the gripping effect of the terrain promoted dust transmission along low-altitude channels.Temporally,fog-and haze-related phenomena occurred mainly during autumn and winter,and the proportion of these events decreased from 76.7%to 55.1%.The fog-and haze-related phenomena demonstrated a U-shaped rebound trend,while the proportion of mist phenomena decreased by 34.2%.Dust storms occurred during spring,accounting for 23.3%to 44.9%of all storms.Instrument measurement technology has the advantages of high spatial and temporal resolutions and multiparameter coordination but provides a limited dust-haze mixed-pollution identification capacity.This study provides crucial reference data for enhancing the understanding of low-visibility events in Xinjiang and the potential responses while improving the accuracy of pollution source tracking and meteorological process diagnosis tasks.
文摘With the rapid development of generative artificial intelligence(GenAI),the task of story visualization,which transforms natural language narratives into coherent and consistent image sequences,has attracted growing research attention.However,existing methods still face limitations in balancing multi-frame character consistency and generation efficiency,which restricts their feasibility for large-scale practical applications.To address this issue,this study proposes a modular cloud-based distributed system built on Stable Diffusion.By separating the character generation and story generation processes,and integratingmulti-feature control techniques,a cachingmechanism,and an asynchronous task queue architecture,the system enhances generation efficiency and scalability.The experimental design includes both automated and human evaluations of character consistency,performance testing,and multinode simulation.The results show that the proposed system outperforms the baseline model StoryGen in both CLIP-I and human evaluation metrics.In terms of performance,under the experimental environment of this study,dual-node deployment reduces average waiting time by approximately 19%,while the four-node simulation further reduces it by up to 65%.Overall,this study demonstrates the advantages of cloud-distributed GenAI in maintaining character consistency and reducing generation latency,highlighting its potential value inmulti-user collaborative story visualization applications.
文摘As global climate change intensifies,alpine plants are facing dual pressures of habitat loss and rapid environmental degradation.As one of the world's most biodiverse countries,China's potential shifts in alpine plant distribution and their profound impact on fragile ecosystems have become a focus of ecological research and conservation efforts,with increasing urgency.Meconopsis,a typical representative of Chinese alpine plants,exhibits diverse adaptability,making it an ideal model for studying how alpine species respond to extreme environmental changes.A lack of comprehensive genus-level analyses may hinder the development of long-term conservation and management strategies.Given the genus's ecological importance,vulnerability,and the risk of trait homogenization in genus-level modeling,there is an urgent need to assess its future distribution patterns,migration trends,and adaptive mechanisms based on habitat classification.In this study,we employed the Maxent model,integrating multidimensional environmental variables,to develop genus-level models and representative habitat-based models(forest,meadows,and periglacial).Results indicate a northwestward expansion and southeastward contraction of suitable habitats under future climate scenarios,with migration patterns in latitude and elevation showing stage-specific characteristics.Key environmental factors varied across models but were mostly associated with seasonal growth traits and microhabitat conditions,highlighting both the universal ecological requirements and niche differentiation within Meconopsis.Based on these findings,we propose a dynamic conservation strategy framework informed by stage-specific responses and habitat differences.Future efforts should focus on incorporating alpine-specific environmental variables and optimizing specimen collection strategies to enhance model performance and support landscape planning and biodiversity conservation.
基金the Chinese Academy of Sciences Research Center for Ecology and Environment of Central Asia(RCEECA),the construction and joint research for the China-Tajikistan“Belt and Road”Joint Laboratory on Biodiversity Conservation and Sustainable Use(2024YFE0214200)the Shanghai Cooperation Organization Partnership and International Technology Cooperation Plan of Science and Technology Projects(2023E01018,2025E01056)the Chinese Academy of Sciences President’s International Fellowship Initiative(PIFI)(2024VBC0006).
文摘Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).
基金supported by ScientificResearch Fund of National Health Commission of the People’s Republic of China-Major Science and Technology Program for Medicine and Health in Zhejiang Province(WKJ-ZJ-2406).
文摘Objectives This study aimed to explore the lagged and cumulative effects of risk factors on disability in older adults using distributed lag non-linear models(DLNMs).Methods We utilized data from the China Health and Retirement Longitudinal Study(CHARLS).After feature selection via Elastic Net Regularization,we applied DLNMs to evaluate the lagged effects of risk factors.Disability was defined as the presence of any difficulties in basic activities of daily living(BADL).The cumulative relative risk(CRR)was calculated by summing the lag-specific risk estimates,representing the cumulative disability risk over the specified lag period.Effect modifications and sensitivity analyses were also performed.Results This study included a total of 2,318 participants.Early-phase lag factors,such as the difficulty in stooping(CRR=3.58;95%CI:2.31-5.55;P<0.001)and walking(CRR=2.77;95%CI:1.39-5.55;P<0.001),exerted the strongest effects immediately upon occurrence.Mid-phase lag factors,such as arthritis(CRR=1.51;95%CI:1.10-2.06;P=0.001),showed a resurgence in disability risk within 2-3 years.Late-phase lag factors,including depressive symptoms(CRR=2.38;95%CI:1.30-4.35;P<0.001)and elevated systolic blood pressure(CRR=1.64;95%CI:1.06-2.79;P=0.02),exhibited significant long-term cumulative risks.Conversely,grip strength(CRR=0.80;95%CI:0.54-0.95;P=0.02)and social participation(CRR=0.89;95%CI:0.73-0.99;P=0.04)were significant protective factors.Conclusions The findings underscore the importance of tailored interventions that account for various lag characteristics of different factors to effectively mitigate disability risk.Future studies should explore the underlying biological and sociological mechanisms of these lagged effects,identify intervention strategies that target risk factors with different lagged patterns,and evaluate their effectiveness.
基金supported by the National Science and Technology Major Project(E152KJ1201)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0036)+1 种基金the National Natural Science Foundation of China(42030105 and 11973046)the National SKA Program of China(2020SKA0120200).
文摘The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.
基金supported by the National Key R&D Program of China(2018YFB0904700).
文摘Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly impact evaluation results.To address this issue,this paper proposes a possibilistic approach to evaluate PV hosting capacity(PVHC).First,possibility distribution is used to model load demand in order to reflect uncertainties associated with human factor,whereas the interval model is applied to deal with uncertainties of PV outputs.Second,a voltage deterioration index is proposed considering overvoltage risk of entire system on time scale.After that,possibilistic PVHC evaluation method based on this index is proposed.A 6-bus system is used to illustrate advantages of the proposed method,followed by a discussion of role of PVHC possibility distribution in actual decision-making of utilities.Moreover,sensitivity of simulation parameters is analyzed to reduce computational burden.Finally,the proposed method is tested on the IEEE 123-bus DN to validate adaptability to a larger system and to analyze impact of PVHC results against different acceptable values set by utilities.
基金supported by Youth Academic Innocation Team Construction project of Capital University of Economics and Business under Grant No.QNTD202303supported by the Beijing Outstanding Young Scientist Program under Grant No.JWZQ20240101027the National Natural Science Foundation of China under Grant Nos.12031016,12531012 and 12426308。
文摘In the era of massive data,the study of distributed data is a significant topic.Model averaging can be effectively applied to distributed data by combining information from all machines.For linear models,the model averaging approach has been developed in the context of distributed data.However,further investigation is needed for more complex models.In this paper,the authors propose a distributed optimal model averaging approach based on multivariate additive models,which approximates unknown functions using B-splines allowing each machine to have a different smoothing degree.To utilize the information from the covariance matrix of dependent errors in multivariate multiple regressions,the authors use the Mahalanobis distance to construct a Mallows-type weight choice criterion.The criterion can be computed by transmitting information between the local machines and the center machine in two steps.The authors demonstrate the asymptotic optimality of the proposed model averaging estimator when the covariates are subject to uncertainty,and obtain the convergence rate of the weight vector to the theoretically optimal weights.The results remain novel even for additive models with a single response variable.The numerical examples show that the proposed method yields good performance.
基金supported by the European Union in the frame of Horizon Europe AVANTIS project,Grant Agreement No.101137552.
文摘Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.
