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Research on heuristic approximation algorithm of the densest k-subgraph discovery in large-scale dynamic graphs
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作者 HAN Tao TIAN Yuxi +1 位作者 ZHAO Jianwei WANG Senzhang 《Journal of Southeast University(English Edition)》 2026年第1期74-79,共6页
To address the issue that static densest subgraph mining algorithms often exhibit low efficiency when handling large scale dynamic graphs,this paper proposes a heuristic approximation algorithm.The algorithm approxima... To address the issue that static densest subgraph mining algorithms often exhibit low efficiency when handling large scale dynamic graphs,this paper proposes a heuristic approximation algorithm.The algorithm approximates the densest k-subgraphs of the entire graph through four steps:partitioning the large-scale dynamic graph,constructing a partial set of the densest k-subgraphs,heuristically merging the subgraph sets,and finally extracting the densest k-subgraphs.This approach significantly reduces the computational time for large-scale dynamic graphs while simultaneously improving the quality of the resulting subgraphs.This algorithm is applicable to various definitions of“density”and can accommodate diverse requirements on the number of edges.When integrated with existing static densest subgraph detection algorithms,it achieves scalability and computational efficiency.Theoretical analysis demonstrates that the optimal density of the densest k-subgraphs extracted by the proposed algorithm reaches 0.9.To evaluate the performance of the algorithm,experiments were conducted on four billion-scale datasets:Friendster,Orkut,YouTube,and DBLP.The results indicate that the proposed algorithm outperforms static methods in both runtime efficiency and subgraph quality on large-scale dynamic graphs. 展开更多
关键词 the densest k-subgraph FEATURES heuristic approximation algorithm optimal density
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PFNA内固定术与DAA人工股骨头置换术治疗老年股骨粗隆间骨折的临床效果比较 被引量:3
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作者 臧夕梁 潘月海 +5 位作者 沈林华 王作锋 蔡程名 王晓君 宋涛 姜志辉 《保健医学研究与实践》 2025年第4期69-75,共7页
目的 比较股骨近端防旋髓内钉(PFNA)内固定术与直接前方入路(DAA)人工股骨头置换术治疗老年股骨粗隆间骨折的临床效果,以期为老年股骨粗隆间骨折患者的临床治疗提供参考。方法 选取2020年1月—2023年1月在中国人民解放军联勤保障部队第... 目的 比较股骨近端防旋髓内钉(PFNA)内固定术与直接前方入路(DAA)人工股骨头置换术治疗老年股骨粗隆间骨折的临床效果,以期为老年股骨粗隆间骨折患者的临床治疗提供参考。方法 选取2020年1月—2023年1月在中国人民解放军联勤保障部队第九七〇医院接受治疗的122例老年股骨粗隆间骨折患者的临床资料进行回顾性分析。根据手术方式不同,将患者分为PFNA内固定术组(n=71)和DAA人工股骨头置换术组(n=51)。比较2组患者的手术相关指标、术前及术后不同时间点髋关节功能、术前及术后12个月骨密度、术后不同时间点股骨颈轴角改变和股骨颈短缩情况,同时记录术后并发症发生情况。结果 PFNA内固定术组患者的手术时间、下地负重时间、住院时间及骨折愈合时间均短于DAA人工股骨头置换术组,切口长度和术中失血量小于DAA人工股骨头置换术组,差异均有统计学意义(P<0.05)。2组患者Harris评分的组间和时间效应及视觉模拟评分法(VAS)评分的时间效应有统计学意义(P<0.05);术后3个月时,PFNA内固定术组患者Harris评分高于DAA人工股骨头置换术组,VAS评分低于DAA人工股骨头置换术组,差异均有统计学意义(P<0.05);术后6、12个月时,2组患者Harris评分和VAS评分比较,差异均无统计学意义(P>0.05)。术后12个月时,2组患者股骨大粗隆、股骨颈及Ward三角的骨密度均高于术前,且PFNA内固定术组均高于DAA人工股骨头置换术组,差异均有统计学意义(P<0.05)。2组患者股骨颈轴角改变、股骨颈短缩程度的组间和时间效应均有统计学意义(P<0.05);各时间点,PFNA内固定术组患者股骨颈轴角改变和股骨颈短缩程度均小于DAA人工股骨头置换术组,差异均有统计学意义(P<0.05)。2组患者住院期间并发症发生率比较,差异均无统计学意义(χ^(2)=1.483,P=0.223)。结论 与DAA人工股骨头置换术相比,PFNA内固定术治疗老年股骨粗隆间骨折具有手术时间短、创伤小、恢复快等优势,有助于促进患者髋关节功能恢复,并维持关节稳定性。 展开更多
关键词 PFNA内固定术 daa人工股骨头置换术 老年股骨粗隆间骨折 临床价值
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基于DAA的采煤机和刮板输送机故障自动识别系统设计及实验 被引量:1
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作者 吴高镇 《煤矿机械》 2025年第11期216-219,共4页
煤矿采煤机和刮板输送机在复杂的工况下容易出现故障。传统故障诊断方式存在模型适应性差、特征提取效率低等问题。基于动态调整算法(DAA)设计了一种故障自动识别系统,通过数据预处理阶段、特征动态提取阶段、自适应决策阶段、闭环反馈... 煤矿采煤机和刮板输送机在复杂的工况下容易出现故障。传统故障诊断方式存在模型适应性差、特征提取效率低等问题。基于动态调整算法(DAA)设计了一种故障自动识别系统,通过数据预处理阶段、特征动态提取阶段、自适应决策阶段、闭环反馈阶段实现对采煤机和刮板输送机故障的自动识别。实验表明,DAA对刮板输送机正常工况、轻载工况、重载工况诊断准确率分别是97.55%、94.58%和93.44%,平均准确率为95.19%;DAA对截割电动机定子绕组短路的单次诊断耗时为12.54 ms,故障预警提前1.22 h,诊断准确率为95.65%;对比固定阈值算法(FTA)和静态权重支持向量机(SW-SVM),可缩短单次诊断耗时,提前对故障进行预警,且诊断准确率显著提升。该系统可为煤矿机械智能化运维提供切实可行的解决方案。 展开更多
关键词 daa 采煤机 刮板输送机 故障自动识别 传感器 人机交互
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DAA支架辅助与仰卧位器械OCM前方入路全髋关节置换术治疗股骨头无菌性坏死疗效 被引量:1
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作者 李鑫 申晓阳 周彬彬 《辽宁医学杂志》 2025年第1期56-59,共4页
目的旨在探讨DAA支架辅助与仰卧位器械OCM前方入路全髋关节置换术治疗股骨头无菌性坏死疗效。方法利用数据表法将2021年3月—2023年3月于本院就诊的110例股骨头无菌性坏死患者随机分为2组,即对照组和实验组,各55例;对照组采用传统后侧... 目的旨在探讨DAA支架辅助与仰卧位器械OCM前方入路全髋关节置换术治疗股骨头无菌性坏死疗效。方法利用数据表法将2021年3月—2023年3月于本院就诊的110例股骨头无菌性坏死患者随机分为2组,即对照组和实验组,各55例;对照组采用传统后侧入路治疗;而实验组则采用DAA支架辅助与仰卧位器械OCM前方入路术,比较两组患者的手术相关指征以及术前、术后3个月的髋关节功能[HHS]、疼痛程度[VAS]、运动功能[FMA-LE]进行评估比较。结果除了手术时间两组患者比较无差异外,实验组患者的术中出血量、术后首次下床时间、并发症发生率以及住院时间均低于对照组(P<0.05);术后3个月,两组患者的Harris、VAS、FMA-LE相较于术前均有改善(P<0.05),其中,实验组患者的Harris、FMA-LE显著高于对照组,而VAS则低于对照组(P<0.05)。结论DAA支架辅助与OCM前方入路全髋关节置换术在股骨头无菌性坏死治疗中效果显著,且能显著提高术后恢复。 展开更多
关键词 daa支架辅助 仰卧位器械 OCM前方入路全髋关节置换术 股骨头无菌性坏死国 髋关节功能
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An Approximation Method for Singular Trudinger-Moser Inequality
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作者 ZHU Maochun XU Wenyan JIANG Rou 《应用数学》 北大核心 2025年第1期64-70,共7页
In this paper,we construct a power type functional which is the approximation functional of the Singular Trudinger-Moser functional.Moreover,we obtain the concentration level of the functional and show it converges to... In this paper,we construct a power type functional which is the approximation functional of the Singular Trudinger-Moser functional.Moreover,we obtain the concentration level of the functional and show it converges to the concentration level of singular Trudinger-Moser functional on the unit ball. 展开更多
关键词 Singular Trudinger-Moser inequality approximation functional Concentration level
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Statistical analysis on the validity of the cold plasma approximation for chorus waves based on Van Allen Probe observations and their effects on radiation belt electrons
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作者 AoJun Ren Jiang Yu +2 位作者 Jing Wang ZuZheng Chen XiaoMan Liu 《Earth and Planetary Physics》 EI CAS 2025年第1期159-170,共12页
Theoretical analysis has demonstrated that the dispersion relation of chorus waves plays an essential role in the resonant interaction and energy transformation between the waves and magnetospheric electrons.Previous ... Theoretical analysis has demonstrated that the dispersion relation of chorus waves plays an essential role in the resonant interaction and energy transformation between the waves and magnetospheric electrons.Previous quantitative analyses often simplified the chorus dispersion relation by using the cold plasma assumption.However,the applicability of the cold plasma assumption is doubtful,especially during geomagnetic disturbances.We here present a systematic statistical analysis on the validity of the cold plasma dispersion relation of chorus waves based on observations from the Van Allen Probes over the period from 2012 to 2018.The statistical results show that the observed magnetic field intensities deviate substantially from those calculated from the cold plasma dispersion relation and that they become more pronounced with an increase in geomagnetic activity or a decrease in background plasma density.The region with large deviations is mainly concentrated in the nightside and expands in both the radial and azimuthal directions as the geomagnetic activity increases or the background plasma density decreases.In addition,the bounce-averaged electron scattering rates are computed by using the observed and cold plasma dispersion relation of chorus waves.Compared with usage of the cold plasma dispersion relation,usage of the observed dispersion relation considerably lowers the minimum resonant energy of electrons and lowers the scattering rates of electrons above tens of kiloelectronvolts but enhances those below.Furthermore,these differences are more pronounced with the enhancement of geomagnetic activity or the decrease in background plasma density. 展开更多
关键词 chorus waves cold plasma approximation dispersion relations scattering rates
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Exceptional Set for Diophantine Approximation with Primes of Two Squares and Three Biquadrates
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作者 LIU Minmin ZHANG Min LI Jinjiang 《数学进展》 北大核心 2025年第1期18-36,共19页
Suppose thatλ_(1),λ_(2),λ_(3),λ_(4),λ_(5)are nonzero real numbers,not all of the same sign,andλ_(1)/λ_(2)is irrational and algebraic.Let V be a well-spaced sequence,δ>0.In this paper,it is proved that,for ... Suppose thatλ_(1),λ_(2),λ_(3),λ_(4),λ_(5)are nonzero real numbers,not all of the same sign,andλ_(1)/λ_(2)is irrational and algebraic.Let V be a well-spaced sequence,δ>0.In this paper,it is proved that,for anyε>0,the number of v∈V with v≤N such that the following inequality|λ_(1)p_(1)~2+λ_(2)p_(2)~2+λ_(3)p_(3)~4+λ_(4)p_(4)~4+λ_5p_5~4-v|<v^(-δ)has no solution in prime variables p_(1),p_(2),p_(3),p_(4),p_(5)does not exceed O(N^(29/32+2δ+ε)). 展开更多
关键词 Diophantine approximation exponential sum Davenport-Heilbronn method prime variable
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Smoluchowski-Kramers Approximation for Stochastic Differential Equations under Discretization
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作者 Li Ge 《应用概率统计》 北大核心 2025年第4期622-635,共14页
This paper studies the Smoluchowski–Kramers approximation for a discrete-time dynamical system modeled as the motion of a particle in a force field.We show that the approximation holds for the drift-implicit Euler–M... This paper studies the Smoluchowski–Kramers approximation for a discrete-time dynamical system modeled as the motion of a particle in a force field.We show that the approximation holds for the drift-implicit Euler–Maruyama discretization and derive its convergence rate.In particular,the solution of the discretized system converges to the solution of the first-order limit equation in the mean-square sense,and this convergence is independent of the order in which the mass parameterμand the step size h tend to zero. 展开更多
关键词 stochastic differential equations Smoluchowski-Kramers approximation driftimplicit Euler-Maruyama scheme convergence rate
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基于DaaS的多源数据融合系统的设计与实现
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作者 邱舒怡 罗林 《IT经理世界》 2025年第1期26-27,共2页
本文探讨了在大数据背景下,企业面临的数据分散、业务数据存储来源多样化,以及在高并发环境下数据共享和访问的挑战。这些问题导致后端开发成本的增加和系统维护的复杂性。为了解决这些核心问题,本文基于数据即服务(Data as a Service,D... 本文探讨了在大数据背景下,企业面临的数据分散、业务数据存储来源多样化,以及在高并发环境下数据共享和访问的挑战。这些问题导致后端开发成本的增加和系统维护的复杂性。为了解决这些核心问题,本文基于数据即服务(Data as a Service,DaaS)的概念,通过整合多源数据管理、数据目录管理和API服务的全周期管理,助力企业实现数据资产化和数据服务化。这不仅减少了后端开发的工作量,还降低了整体的开发和维护成本,使得数据能够更有效地服务于业务需求。 展开更多
关键词 daaS 数据库管理 系统设计
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A reconfigurable array with adaptive approximation using dual threshold accuracy
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作者 SHAN Rui SONG Yupeng LIAO Wang 《High Technology Letters》 2025年第3期226-237,共12页
With the growing demand for compute-intensive applications such as artificial intelligence(AI)and video processing,traditional reconfigurable array processors fail to meet the requirements of high-performance computin... With the growing demand for compute-intensive applications such as artificial intelligence(AI)and video processing,traditional reconfigurable array processors fail to meet the requirements of high-performance computing and related domains,primarily due to their high power consumption and low energy efficiency.To address this limitation,this paper proposes an accuracy-adaptive approxi-mate reconfigurable array architecture featuring preset dual thresholds and support for four computa-tional accuracy levels,enabling flexible adaptation to diverse application needs.The architecture in-tegrates a self-adaptive mechanism that dynamically adjusts computational precision based on real-time error threshold feedback.To evaluate the proposed architecture,the you only look once version 5(YOLOv5)deep neural network algorithm is parallelized and deployed on the approximate recon-figurable array.Experimental results demonstrate that the architecture achieves an 18.93%reduc-tion in power consumption compared with conventional reconfigurable structures operating in full-pre-cision mode.Additionally,the design exhibits superior energy efficiency and reduced computational resource utilization,thereby significantly enhancing the overall performance and applicability of reconfigurable array processors in power-sensitive scenarios. 展开更多
关键词 reconfigurable computing approximate computing low power ENERGY-EFFICIENT
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On approximation of Bernstein-Stancu operators in movable interval
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作者 WAGN Feng-feng YU Dan-sheng 《Applied Mathematics(A Journal of Chinese Universities)》 2025年第1期85-101,共17页
In the present paper,we obtain the converse results of approximation of a newly introduced genuine Bernstein-Durrmeyer operators in movable interval.We also get the moments properties of an auxiliary operator which ha... In the present paper,we obtain the converse results of approximation of a newly introduced genuine Bernstein-Durrmeyer operators in movable interval.We also get the moments properties of an auxiliary operator which has its own independent values.The moments of the auxiliary operators play important roles in establishing the main result(Theorem 4). 展开更多
关键词 Bernstein-Stancu operators movable interval approximation rates Voronovskaja's asymptotic estimate
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A new oolitic content test method for green sand by repeated approximation
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作者 Yu-yang Qi Jian-xin Zhou +6 位作者 Xin Peng Si-yuan Pan Ya-jun Yin Xiao-yuan Ji Yuan-cai Li Peng-fei Lin Peng Wan 《China Foundry》 2025年第6期701-709,共9页
The reuse of green sand in casting production is hindered by the accumulation of oolitic deposits,primarily composed of clay binder with surface degradation,which may adversely affect the the moulding sand performance... The reuse of green sand in casting production is hindered by the accumulation of oolitic deposits,primarily composed of clay binder with surface degradation,which may adversely affect the the moulding sand performance.Currently,there is a lack of standardized methods for quantifying the oolitic content.Accurate measurement of oolitic content is of great significance to the reuse of green sand.Attempts to determine oolitic content using potassium hydroxide(KOH)and phosphoric acid(H_(3)PO_(4))methods encounter challenges due to their excessive reactions with SiO_(2) in the sand.In this study,an improved method for measuring the oolitic content of green sand with repeated approximations was proposed.This method judges the chemical activity of the sample surface through the change of its mass to accurately obtain the mass of the reaction oolitic deposits.The test result of the used sand samples from the foundry shows that the oolitic deposits are completely removed after reacting with KOH solution three times at 300℃ for 20 min.SEM and EDS also show that after three times of reactions,the surface of green sand becomes smooth and the content of Al-containing oolitic deposits is very low.This indicates that the method can accurately control the extent of the reaction.Implementation of this method at Huangshi Dongbei Casting Co.,Ltd.has yielded consistent and reliable test results,effectively mirroring variations in green sand oolitic content on the production line.This new method is expected to be widely adopted to improve the efficiency and quality of reused green sand in casting operations. 展开更多
关键词 green sand oolitic content repeated approximation reuse of green sand
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Adaptive polynomial approximation-based virtual coupled cooperative control for high-speed trains
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作者 Kai-Xiang Wang Ming-Yue Ren +1 位作者 Qian-Ling Wang Xue Lin 《Chinese Physics B》 2025年第10期589-596,共8页
Virtual coupling is a novel technology that enables trains to run closely together without physical connections through communication and automation systems.The paper addresses an adaptive polynomial approximation alg... Virtual coupling is a novel technology that enables trains to run closely together without physical connections through communication and automation systems.The paper addresses an adaptive polynomial approximation algorithm for the cooperative control of high-speed trains(HSTs)under virtual coupling.It aims to solve the cooperative tracking control problem of HST formation operations under various scenarios,including known and unknown parameters.To enable the HST formation system to achieve cooperative operation while ensuring an appropriate spacing distance,the tracking errors of displacement and speed throughout the entire operation converge to zero.The proposed control strategy focuses on adopting polynomial approximation to handle unknown parameters,which are estimated via adaptive laws.Additionally,the unknown parameters of the HSTs are estimated online through adaptive laws.Experimental results verify the effectiveness of this method. 展开更多
关键词 high-speed trains(HSTs) cooperative operation adaptive polynomial approximation virtual coupling
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Optimal convex approximations of qubit states based on l_(1)-norm of coherence
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作者 Li-Qiang Zhang Yan-Dong Du Chang-Shui Yu 《Chinese Physics B》 2025年第8期475-491,共17页
Determining the minimal distance between the target state and the convex combination of given states is a fundamental problem in quantum resource theory,offering critical guidance for experimental implementations.In t... Determining the minimal distance between the target state and the convex combination of given states is a fundamental problem in quantum resource theory,offering critical guidance for experimental implementations.In this paper,we embark on an in-depth exploration of the use of a quantum state prepared by the convex combination of given qubit states to optimally approximate the l_(1)-norm of coherence of the target quantum state,striving to make the prepared state and the target state as similar as possible.Here,we present the analytical solution for the optimal distance for any N given quantum states.We find that the optimal approximation problem for any N>4 quantum states can be transformed into an optimal approximation problem for no more than four quantum states,which not only significantly streamlines the problem but also proves advantageous for laboratories in terms of material conservation.Ultimately,a one-to-one comparison between the analytical and numerical solutions verifies the effectiveness of our approach. 展开更多
关键词 quantum information processing quantum resource theory quantum coherence optimal convex approximations
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Multi-Interval-Aggregation Failure Point Approximation for Remaining Useful Life Prediction
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作者 Linchuan Fan Xiaolong Chen +1 位作者 Shuo Li Yi Chai 《IEEE/CAA Journal of Automatica Sinica》 2025年第3期639-641,共3页
Dear Editor,This letter focuses on the remaining useful life(RUL)prediction task under limited labeled samples.Existing machine-learning-based RUL prediction methods for this task usually pay attention to mining degra... Dear Editor,This letter focuses on the remaining useful life(RUL)prediction task under limited labeled samples.Existing machine-learning-based RUL prediction methods for this task usually pay attention to mining degradation information to improve the prediction accuracy of degradation value or health indicator for the next epoch.However,they ignore the cumulative prediction error caused by iterations before reaching the failure point. 展开更多
关键词 remaining useful life prediction failure point degradation value health indicator multi interval aggregation failure point approximation machine learning based mining degradation information
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Fast Ion Gates without the Lamb-Dicke Approximation by Robust Quantum Optimal Control
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作者 Ran Liu Xiaodong Yang +2 位作者 Yiheng Lin Yao Lu Jun Li 《Chinese Physics Letters》 2025年第8期75-82,共8页
We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of ... We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments. 展开更多
关键词 quantum optimal control framework gradient based optimal control quantum computation Lamb Dicke approximation fast ion gates tailored laser pulses entangling gates robust quantum optimal control
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太阳辐射/对流区域边界处的碳、氮、氧元素的电子碰撞电离研究
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作者 侯永 罗青波 +2 位作者 梁欣 曾交龙 袁建民 《物理学报》 北大核心 2026年第1期220-230,共11页
太阳辐射层与对流层边界区域T≈180eV,ne≈9×10^(22)cm^(-3),是太阳内部能量传输方式从辐射主导向对流主导转变的关键界面,也是研究高温稠密等离子体物理的天然实验室.这一区域的物理特性决定了恒星演化模型的可靠性与能量传输机... 太阳辐射层与对流层边界区域T≈180eV,ne≈9×10^(22)cm^(-3),是太阳内部能量传输方式从辐射主导向对流主导转变的关键界面,也是研究高温稠密等离子体物理的天然实验室.这一区域的物理特性决定了恒星演化模型的可靠性与能量传输机制的稳定性,特别是高温稠密等离子体中强烈的碰撞电离会改变电子数密度分布,进而影响能量的输运过程.本文发展了一种耦合等离子体环境效应来计算原子结构的新方法:通过将计算原子结构的Flexible Atomic Code (FAC)与超网链(hypernetted-chain, HNC)近似相结合,在原子波函数计算中引入电子-电子、电子-离子关联函数来考虑等离子体中屏蔽效应,系统研究了极端条件下电子碰撞电离的物理机制.基于扭曲波近似的计算表明,考虑等离子体环境效应时,碳、氮和氧元素的电子碰撞电离截面较自由原子模型显著增强,同时电离阈值出现明显下降的现象.研究发现这种增强效应主要源于离子间强耦合导致的原子势场重叠和自由电子屏蔽引起的束缚态能级移动.本研究直接将离子结构引入电子结构计算的哈密顿量中,所获得的电离参数可直接用于改进太阳内部辐射输运模型,为惯性约束聚变等极端条件等离子体研究提供了理论支持. 展开更多
关键词 辐射/对流区域边界 环境效应 电子碰撞电离 超网链近似
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冲击荷载下球壳顶点动力响应及凹陷半径研究
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作者 吴长 王化鑫 +2 位作者 张丹 杨佑佩 张悦瀚 《兰州理工大学学报》 北大核心 2026年第1期135-141,共7页
通过建立球面网壳结构冲击区在三角形脉冲荷载下的运动方程,推导结构体系的动力响应及反应比;同时基于近似能量原理,计算球面网壳结构在冲击作用下的塑性大变形,对结构顶点受到单点冲击作用时壳体凹陷区域的半径做简化推导,并在ANSYS/LS... 通过建立球面网壳结构冲击区在三角形脉冲荷载下的运动方程,推导结构体系的动力响应及反应比;同时基于近似能量原理,计算球面网壳结构在冲击作用下的塑性大变形,对结构顶点受到单点冲击作用时壳体凹陷区域的半径做简化推导,并在ANSYS/LS-DYNA中建立K6型单层球面网壳模型对表达式进行数值模拟验证.研究表明:结构最大反应的主要影响因素为冲击荷载的作用时长及结构体系的自振频率.凹陷半径受球壳结构自身的曲率半径、等效厚度、棱区宽度、结构材料的屈服应力和结构吸收冲击能量的大小等因素的影响,且理论值与模拟值较为接近. 展开更多
关键词 网壳结构 动力响应 塑性变形 近似能量原理 冲击荷载
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悬链线及圆锥曲线混合柔性铰链设计与分析
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作者 谢祖强 陈贵清 《机械传动》 北大核心 2026年第1期100-111,共12页
【目的】既有的柔性铰链研究都对应着复杂的柔度和回转精度计算式。为了解决该问题,设计了一种新型悬链线形柔性铰链,提出一种用直线段逼近弧段建立铰链柔度和回转精度模型的方法。【方法】首先,将柔性铰链定义为渐缩段与渐扩段的串联组... 【目的】既有的柔性铰链研究都对应着复杂的柔度和回转精度计算式。为了解决该问题,设计了一种新型悬链线形柔性铰链,提出一种用直线段逼近弧段建立铰链柔度和回转精度模型的方法。【方法】首先,将柔性铰链定义为渐缩段与渐扩段的串联组合,将渐缩段中曲线段分割成若干弧段,用直线段逼近弧段;基于卡氏第二定理,计算铰链渐缩段柔度,由矩阵运算建立铰链柔度和回转精度模型;其次,结合具体算例,采用推出公式、文献公式和有限元法计算,当曲线分割段数较大时,计算结果吻合较好,验证了公式正确性;再次,分析了结构参数对悬链线铰链柔度、回转精度和柔度精度比的影响;最后,分析了相同结构参数下悬链线、圆锥曲线及其混合铰链的弯曲柔度和柔度精度比。【结果】结果表明,单一参数对悬链线铰链柔度和回转精度的影响成负相关,减小最薄处厚度是提升其柔度的最佳方式。相同结构参数下,悬链线铰链弯曲柔度和柔度精度比介于抛物线和圆弧形之间。选择柔度大的为渐缩段、柔度小的为渐扩段的混合型铰链可兼顾柔度和回转精度;柔度悬殊越大,越有利于提升柔度精度比。 展开更多
关键词 悬链线柔性铰链 混合柔性铰链 渐缩段 直线逼近 柔度建模
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综合能源系统安全域边界近似的多项式混沌展开方法
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作者 姜涛 王璇瑶 +1 位作者 李雪 李国庆 《中国电机工程学报》 北大核心 2026年第2期620-633,I0014,共15页
为构建综合能源系统安全域(integrated energy system security region,IESSR),该文提出一种基于多项式混沌展开(polynomial chaos expansion,PCE)的IESSR边界(IESR boundary,IESSRB)近似方法,借助该方法可得IESSRB的多项式逼近表达式... 为构建综合能源系统安全域(integrated energy system security region,IESSR),该文提出一种基于多项式混沌展开(polynomial chaos expansion,PCE)的IESSR边界(IESR boundary,IESSRB)近似方法,借助该方法可得IESSRB的多项式逼近表达式。首先,根据IESSRB的边界拓扑特性,构建系统的IESSR边界点搜索优化模型;然后,根据PCE,对IESSR边界点搜索优化模型进行参数化处理,构建IESSRB搜索的参数化优化模型;进一步地,根据IESSRB搜索的参数化优化模型的KKT条件,将IESSRB的参数化优化模型转化为高维参数化非线性方程组;在此基础上,借助广义Galerkin投影构建关于近似IESSRB的多项式逼近系数的Galerkin投影方程组,通过求解该方程组可得IESSRB的多项式逼近系数,从而获得IESSRB的多项式逼近表达式;为进一步降低Galerkin投影方程组求解复杂度,提出多项式分段近似IESSRB方法,在提高IESSRB近似精度的同时,提升了IESSRB近似的计算效率;最后,通过IES E39-G20测试系统和IES E118-G96测试系统对所提方法进行分析、验证。结果表明,所提方法可实现IESSR的准确、有效构建。 展开更多
关键词 综合能源系统 安全域 安全域边界 多项式混沌展开 Galerkin投影 多项式逼近表达式
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