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Delay-Differentiated Scheduling in Optical Packet Switches for Cloud Data Centers 被引量:2
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作者 LI Yaofang XIAO Jie +5 位作者 WU Bin WEN Hong YU Hongfang YANG Shu XIN Shanshan GUO Jianing 《China Communications》 SCIE CSCD 2015年第8期22-32,共11页
We consider differentiated timecritical task scheduling in a N×N input queued optical packet s w itch to ens ure 100% throughput and meet different delay requirements among various modules of data center. Existin... We consider differentiated timecritical task scheduling in a N×N input queued optical packet s w itch to ens ure 100% throughput and meet different delay requirements among various modules of data center. Existing schemes either consider slot-by-slot scheduling with queue depth serving as the delay metric or assume that each input-output connection has the same delay bound in the batch scheduling mode. The former scheme neglects the effect of reconfiguration overhead, which may result in crippled system performance, while the latter cannot satisfy users' differentiated Quality of Service(Qo S) requirements. To make up these deficiencies, we propose a new batch scheduling scheme to meet the various portto-port delay requirements in a best-effort manner. Moreover, a speedup is considered to compensate for both the reconfiguration overhead and the unavoidable slots wastage in the switch fabric. With traffic matrix and delay constraint matrix given, this paper proposes two heuristic algorithms Stringent Delay First(SDF) and m-order SDF(m-SDF) to realize the 100% packet switching, while maximizing the delay constraints satisfaction ratio. The performance of our scheme is verified by extensive numerical simulations. 展开更多
关键词 delay-differentiated packetscheduling optical switch data center cloudservice
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Computational and experimental verification of a wide-angle metamaterial absorber
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作者 陈超 王君 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第4期179-183,共5页
A metamaterial absorber is computed numerically and measured experimentally in a 150-THz^300-THz range.The measured absorber achieves high absorption rate for both transverse electric(TE) and transverse magnetic(TM... A metamaterial absorber is computed numerically and measured experimentally in a 150-THz^300-THz range.The measured absorber achieves high absorption rate for both transverse electric(TE) and transverse magnetic(TM) polarizations at large angles of incidence.An absorption sensor scheme is proposed based on the measured absorber and the variations of surrounding media.Different surrounding media are applied to the surface of the absorption sensor(including air,water,and glucose solution).Measured results show that high figure of merit(FOM) values are obtained for different surrounding media.The proposed sensor does not depend on the substrate,which means that it can be transplanted to different sensing platforms conveniently. 展开更多
关键词 SENSORS METAMATERIALS simulation calculations
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Optimized Runge-Kutta Methods with Automatic Step Size Control for Compressible Computational Fluid Dynamics
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作者 Hendrik Ranocha Lisandro Dalcin +1 位作者 Matteo Parsani David I.Ketcheson 《Communications on Applied Mathematics and Computation》 2022年第4期1191-1228,共38页
We develop error-control based time integration algorithms for compressible fluid dynam-ics(CFD)applications and show that they are efficient and robust in both the accuracy-limited and stability-limited regime.Focusi... We develop error-control based time integration algorithms for compressible fluid dynam-ics(CFD)applications and show that they are efficient and robust in both the accuracy-limited and stability-limited regime.Focusing on discontinuous spectral element semidis-cretizations,we design new controllers for existing methods and for some new embedded Runge-Kutta pairs.We demonstrate the importance of choosing adequate controller parameters and provide a means to obtain these in practice.We compare a wide range of error-control-based methods,along with the common approach in which step size con-trol is based on the Courant-Friedrichs-Lewy(CFL)number.The optimized methods give improved performance and naturally adopt a step size close to the maximum stable CFL number at loose tolerances,while additionally providing control of the temporal error at tighter tolerances.The numerical examples include challenging industrial CFD applications. 展开更多
关键词 Explicit Runge-Kutta methods Step size control Compressible Euler equations Compressible Navier-Stokes equations hp-adaptive spatial discretizations
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LiDAR-Visual SLAM with Integrated Semantic and Texture Information for Enhanced Ecological Monitoring Vehicle Localization
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作者 Yiqing Lu Liutao Zhao Qiankun Zhao 《Computers, Materials & Continua》 SCIE EI 2025年第1期1401-1416,共16页
Ecological monitoring vehicles are equipped with a range of sensors and monitoring devices designed to gather data on ecological and environmental factors.These vehicles are crucial in various fields,including environ... Ecological monitoring vehicles are equipped with a range of sensors and monitoring devices designed to gather data on ecological and environmental factors.These vehicles are crucial in various fields,including environmental science research,ecological and environmental monitoring projects,disaster response,and emergency management.A key method employed in these vehicles for achieving high-precision positioning is LiDAR(lightlaser detection and ranging)-Visual Simultaneous Localization and Mapping(SLAM).However,maintaining highprecision localization in complex scenarios,such as degraded environments or when dynamic objects are present,remains a significant challenge.To address this issue,we integrate both semantic and texture information from LiDAR and cameras to enhance the robustness and efficiency of data registration.Specifically,semantic information simplifies the modeling of scene elements,reducing the reliance on dense point clouds,which can be less efficient.Meanwhile,visual texture information complements LiDAR-Visual localization by providing additional contextual details.By incorporating semantic and texture details frompaired images and point clouds,we significantly improve the quality of data association,thereby increasing the success rate of localization.This approach not only enhances the operational capabilities of ecological monitoring vehicles in complex environments but also contributes to improving the overall efficiency and effectiveness of ecological monitoring and environmental protection efforts. 展开更多
关键词 LiDAR-Visual simultaneous localization and mapping integrated semantic texture information
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Structural vibration control using nonlinear damping amplifier friction vibration absorbers
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作者 S.CHOWDHURY S.ADHIKARI 《Applied Mathematics and Mechanics(English Edition)》 2025年第5期965-988,共24页
This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered ... This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads. 展开更多
关键词 damping amplifier friction vibration absorber(DAFVA) compound damping amplifier friction vibration absorber(CDAFVA) nested damping amplifier friction vibration absorber(NDAFVA) levered damping amplifier friction vibration absorber(LDAFVA) H2 and H∞optimization approaches
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Explainable AI Based Multi-Task Learning Method for Stroke Prognosis
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作者 Nan Ding Xingyu Zeng +1 位作者 Jianping Wu Liutao Zhao 《Computers, Materials & Continua》 2025年第9期5299-5315,共17页
Predicting the health status of stroke patients at different stages of the disease is a critical clinical task.The onset and development of stroke are affected by an array of factors,encompassing genetic predispositio... Predicting the health status of stroke patients at different stages of the disease is a critical clinical task.The onset and development of stroke are affected by an array of factors,encompassing genetic predisposition,environmental exposure,unhealthy lifestyle habits,and existing medical conditions.Although existing machine learning-based methods for predicting stroke patients’health status have made significant progress,limitations remain in terms of prediction accuracy,model explainability,and system optimization.This paper proposes a multi-task learning approach based on Explainable Artificial Intelligence(XAI)for predicting the health status of stroke patients.First,we design a comprehensive multi-task learning framework that utilizes the task correlation of predicting various health status indicators in patients,enabling the parallel prediction of multiple health indicators.Second,we develop a multi-task Area Under Curve(AUC)optimization algorithm based on adaptive low-rank representation,which removes irrelevant information from the model structure to enhance the performance of multi-task AUC optimization.Additionally,the model’s explainability is analyzed through the stability analysis of SHAP values.Experimental results demonstrate that our approach outperforms comparison algorithms in key prognostic metrics F1 score and Efficiency. 展开更多
关键词 Explainable AI stroke prognosis multi-task learning AUC optimization
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Application of aluminum industry solid waste in asphalt mixtures and its impact on performance:Current research and future perspectives
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作者 Tianyi Yan Yongjun Meng +3 位作者 Xiaowan Luo Jinbin Chen Keyu Yan Dawei Wang 《Journal of Road Engineering》 2025年第4期554-571,共18页
Aluminum industrial solid waste represents a highly abundant yet underutilized resource.Its incorporation into asphalt pavement applications can effectively reduce the exploitation of natural resources and mitigate en... Aluminum industrial solid waste represents a highly abundant yet underutilized resource.Its incorporation into asphalt pavement applications can effectively reduce the exploitation of natural resources and mitigate environmental issues caused by waste accumulation.This paper focuses on typical solid waste resources generated by the aluminum industry,summarizing the latest research progress in their application within the asphalt pavement industry and proposing key directions for future attention.The physicochemical properties of red mud(RM),spent aluminum electrolytic cathode materials,and secondary aluminum dross(SAD)are reviewed.The effects and mechanisms of RM,spent aluminum electrolytic cathode materials,and SAD on the performance of asphalt and its mixtures are elaborated.RM significantly enhances the aging resistance of asphalt,the hightemperature rheological properties of asphalt mastic,and the rutting resistance of asphalt mixtures.Spent aluminum electrolytic cathode materials require the removal of fluorides and cyanides before further application in asphalt pavement.SAD effectively improves the dynamic stability of asphalt mixtures.This review presents the first systematic summary of key scientific challenges and technical bottlenecks in the application of aluminum industrial solid waste in asphalt pavements.It clarifies that future research should prioritize waste pretreatment technologies,performance regulation mechanisms,and life cycle environmental impact assessments.These contributions provide essential theoretical foundations and technical guidance for advancing the resource utilization of aluminum industrial solid waste,holding substantial significance for promoting the development of green transportation infrastructure. 展开更多
关键词 Aluminum industry solid waste Asphalt mastic Asphalt mixtures Red mud Spent aluminum electrolytic cathode materials Secondary aluminum dross
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Boosting cationic and anionic redox activity of Li-rich layered oxide cathodes via Li/Ni disordered regulation
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作者 Zewen Liu Zhen Wu +7 位作者 Hao Wang Xudong Zhang Yuanzhen Chen Yongning Liu Shengwu Guo Shenghua Chen Yanli Nan Yan Liu 《Journal of Energy Chemistry》 2025年第1期533-543,共11页
Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial ... Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes. 展开更多
关键词 Low-Co Li-rich layered oxides Li/Ni disordering TM-O covalency Cationic and anionic redox activity
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Production of exotic hadrons in pp and nuclear collisions
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作者 Jin-Hui Chen Feng-Kun Guo +5 位作者 Yu-Gang Ma Cheng-Ping Shen Qi-Ye Shou Qian Wang Jia-Jun Wu Bing-Song Zou 《Nuclear Science and Techniques》 2025年第4期1-22,共22页
Exotic hadrons,beyond the conventional quark model,have been discovered over the past two decades.Investigating these states can lead to a deeper understanding of the nonperturbative dynamics of the strong interaction... Exotic hadrons,beyond the conventional quark model,have been discovered over the past two decades.Investigating these states can lead to a deeper understanding of the nonperturbative dynamics of the strong interaction.In this review,we focus on the production of exotic hadrons in pp,PP^(-),and nuclear collisions.Experimental observations of light and hypernuclei as prototypes of hadronic molecules in heavy-ion collisions are also briefly discussed. 展开更多
关键词 Exotic hadrons Hadron-hadron collision Heavy-ion collision
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A survey on textual emotion cause extraction in social networks
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作者 Sancheng Peng Lihong Cao +3 位作者 Guojun Wang Zhouhao Ouyang Yongmei Zhou Shui Yu 《Digital Communications and Networks》 2025年第2期524-536,共13页
With the rapid development of web technology,Social Networks(SNs)have become one of the most popular platforms for users to exchange views and to express their emotions.More and more people are used to commenting on a... With the rapid development of web technology,Social Networks(SNs)have become one of the most popular platforms for users to exchange views and to express their emotions.More and more people are used to commenting on a certain hot spot in SNs,resulting in a large amount of texts containing emotions.Textual Emotion Cause Extraction(TECE)aims to automatically extract causes for a certain emotion in texts,which is an important research issue in natural language processing.It is different from the previous tasks of emotion recognition and emotion classification.In addition,it is not limited to the shallow-level emotion classification of text,but to trace the emotion source.In this paper,we provide a survey for TECE.First,we introduce the development process and classification of TECE.Then,we discuss the existing methods and key factors for TECE.Finally,we enumerate the challenges and developing trend for TECE. 展开更多
关键词 TEXT EMOTION Emotion cause Machine learning Deep learning
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三聚氰胺金属(Ⅱ)配合物的结构、紫外-可见光谱和反应活性 被引量:14
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作者 钟爱国 吴俊勇 +5 位作者 闫华 金燕仙 戴国梁 蒋华江 潘富友 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2009年第7期1367-1372,共6页
三聚氰胺是婴幼儿"肾结石事件"的重要前体.本文选取几个典型的二价金属离子与三聚氰胺(L)形成的三聚氰胺金属配合物ML2(OH)2(M=Ca,Mg,Zn,Cu,Ni,Fe),使用密度泛函理论(DFT)、含时DFT和概念DFT等工具,系统地计算和比较了ML2(OH)... 三聚氰胺是婴幼儿"肾结石事件"的重要前体.本文选取几个典型的二价金属离子与三聚氰胺(L)形成的三聚氰胺金属配合物ML2(OH)2(M=Ca,Mg,Zn,Cu,Ni,Fe),使用密度泛函理论(DFT)、含时DFT和概念DFT等工具,系统地计算和比较了ML2(OH)2的结构、紫外-可见光谱和反应性质的异同.模拟结果揭示了ML2(OH)2的结构、光谱及其反应性质是一类不同于其前体L,形成ML2(OH)2配合物后,将有较高的亲电指数和较低的化学硬度以及呈现红外吸收峰红移;在这些典型的二价金属配合物中,金属M离子电荷与配体O和N原子之间的电荷、以及与金属M离子和配体原子之间的二级微扰相互作用能,配合物最低空轨道能级与其亲电反应指数、最低空轨道能级与化学硬度指数等方面,存在着一系列定量的相关关系,相关系数(R2)达0.889-0.997;前线分子轨道模拟结果表明,ML2(OH)2体系反应活性的差异源于金属离子对前线轨道贡献有所不同,FeL2(OH)2、CuL2(OH)2、NiL2(OH)2等过渡金属离子的配合物中,金属离子贡献较多,共价性成分较多.这些结果将为进一步理解人体内三聚氰胺致结石的成因提供有益的启示. 展开更多
关键词 DFT 三聚氰胺 三聚氰胺金属配合物 概念DFT 含时DFT
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双螺旋金属(Ⅱ)卟啉的结构、电子光谱及其反应活性 被引量:9
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作者 钟爱国 黄凌 +2 位作者 李佰林 蒋华江 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2010年第10期2763-2771,共9页
由两个拓展的卟吩环键合不同的金属离子形成的卟啉结分子是生命体系中DNA双螺旋分子最简单的金属扭结模型物,在仿酶催化反应等方面存在广阔的应用空间.本文选取8个典型的二价金属离子(M(Ⅱ),M=Ca,Mg,Mn,Zn,Cu,Ni,Fe,Co)与拓展卟吩结分子... 由两个拓展的卟吩环键合不同的金属离子形成的卟啉结分子是生命体系中DNA双螺旋分子最简单的金属扭结模型物,在仿酶催化反应等方面存在广阔的应用空间.本文选取8个典型的二价金属离子(M(Ⅱ),M=Ca,Mg,Mn,Zn,Cu,Ni,Fe,Co)与拓展卟吩结分子(1H)形成的单金属卟啉结配合物(1M)和双金属卟啉结配合物(2M),用密度泛函理论(DFT)、含时DFT和概念DFT等工具,在优化构型的基础上,通过自然键轨道(NBO)方法和前线轨道能级研究了它们的分子结构、光谱性质和反应活性.模拟结果显示1M、2M的结构、光谱及其反应性质不同于其前体1H:形成1M和2M金属配合物分子后,将有较高的亲电指数和较低的化学硬度以及呈现紫外吸收峰位移;形成2M双金属配合物后,绝大多数金属离子形成的2个四配位环境的对称性较1M体系有了提高,同时DFT反应指数也有显著的增强.但2M体系的调变能力也不尽相同:主簇金属和含饱和电子结构离子较弱,过渡金属离子强些,二元描述符(dual descriptor)结果支持了以上结论.在这些典型的二价金属配合物中,金属原子M和配体原子N之间的自然电荷分布,金属原子M和配体原子N之间的二级微扰相互作用能,配合物的前线轨道能级与其硬度指数、键的离解能与自然电荷等方面,存在着一系列定量的相关关系,相关系数(R2)在0.858-0.986之间.本研究对理解含有金属离子的重要生物物质在结构和反应性能上的差别将提供有益启示. 展开更多
关键词 电子光谱 拓展卟吩 金属卟啉 螺旋分子 密度泛函理论
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双核镉配聚体及其衍生物荧光光谱发光机理的计算化学研究 被引量:3
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作者 黄莺 刘文龙 +1 位作者 钟爱国 刘述斌 《晓庄学院自然科学学报》 CAS 北大核心 2010年第4期69-74,共6页
采用密度泛函理论(DFT)在B3LYP/6-311+G(d)水平上,对双核镉配聚物1[Cd2Cl4(Hbm)2](Hbm=1H-benzimidazol-2-ylmethanol)及其5种衍生物([M2Cl4(Hbm)(Hbm-R)],M=Zn2+,Hg2+;R=—CH3;—NH2;—CN)的荧光光谱的发光机理进行了研究.对其基态结... 采用密度泛函理论(DFT)在B3LYP/6-311+G(d)水平上,对双核镉配聚物1[Cd2Cl4(Hbm)2](Hbm=1H-benzimidazol-2-ylmethanol)及其5种衍生物([M2Cl4(Hbm)(Hbm-R)],M=Zn2+,Hg2+;R=—CH3;—NH2;—CN)的荧光光谱的发光机理进行了研究.对其基态结构进行全优化,用含时密度泛函理论(TD-DFT)在B3LYP/6-311+G(d)水平上计算其吸收光谱;同时采用CIS/6-31G(d)方法优化其最低激发单重态S1的几何结构,并用TD-DFT计算其发射光谱.结果表明,电子在基态S0与激发态S1间的跃迁,主要是在卤素配体到金属离子之间的电荷转移;模拟的吸收光谱和发射光谱峰的计算最大值与实验值基本吻合.改变中心金属离子和咪唑环上的取代基可以调控发光材料的光谱波段.此外,运用密度泛函活性理论(DFRT)研究了它们的电子结构和反应活性,发现金属离子的亲电福井指数与分子的发射光波长存在较好的相关性,相关系数(R2)达0.993.这些结果将对苯并咪唑类电(光)致发光材料的分子设计以及其他电致发光材料的分子模拟提供有益的启示. 展开更多
关键词 镉配聚物 发射光谱 密度泛函理论 含时密度泛函理论 密度泛函活性理论
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密度泛函活性理论中的Rényi熵,Tsallis熵和Onicescu信息能(英文) 被引量:4
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作者 刘述斌 荣春英 +1 位作者 吴泽民 卢天 《物理化学学报》 SCIE CAS CSCD 北大核心 2015年第11期2057-2063,共7页
根据密度泛函理论,分子的电子密度确定了该体系基态下的所有性质,其中包括结构和反应活性.如何运用电子密度泛函有效地预测分子反应活性仍然是一个有待解决的难题.密度泛函活性理论(DFRT)倾力打造这样一个理论和概念架构,使得运用电子... 根据密度泛函理论,分子的电子密度确定了该体系基态下的所有性质,其中包括结构和反应活性.如何运用电子密度泛函有效地预测分子反应活性仍然是一个有待解决的难题.密度泛函活性理论(DFRT)倾力打造这样一个理论和概念架构,使得运用电子密度以及相关变量准确地预测分子的反应特性成为可能.信息理论方法的香农熵和费舍尔信息就是这样的密度泛函,研究表明,它们均可作为反应活性的有效描述符.本文将在DFRT框架中介绍和引进三个密切相关的描述符,Rényi熵、Tsallis熵和Onicescu信息能.我们准确地计算了它们在一些中性原子和分子中的数值并讨论了它们随电子数量和电子总能量的变化规律.此外,以第二阶Onicescu信息能为例,在分子和分子中的原子两个层面上,系统地考察了其随乙烷二面角旋转的变化模式.这些新慨念的引入将为我们深入洞察和预测分子的结构和反应活性提供额外的描述工具. 展开更多
关键词 Rényi熵 TSALLIS熵 Onicescu信息能 香农熵 密度泛函活性理论
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面向并行文件系统的性能评估及相对预测模型 被引量:7
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作者 赵铁柱 董守斌 +1 位作者 Verdi MARCH Simon SEE 《软件学报》 EI CSCD 北大核心 2011年第9期2206-2221,共16页
基于Lustre文件系统,对并行文件系统的性能评估和性能建模进行了研究.通过对性能因子的调研,进行了一系列性能评估实验,并提出性能相关性模~(PRModel).在实验评估和PRModel分析中发现,在不同的性能因子之间存在着紧密的性能相... 基于Lustre文件系统,对并行文件系统的性能评估和性能建模进行了研究.通过对性能因子的调研,进行了一系列性能评估实验,并提出性能相关性模~(PRModel).在实验评估和PRModel分析中发现,在不同的性能因子之间存在着紧密的性能相关性,为了挖掘并利用这种相关性信息,提出了一种相对性能预测模(RPPModel)来预测不同性能因子条件下的性能.为了验证RPPModel的有效性,设计了大量实验用例.结果表明,预测结果的平均相对误差能够控制在170/o---28%的范围内,易于使用且具有较好的预测准确度. 展开更多
关键词 并行文件系统 性能评估 性能模型 LUSTRE文件系统
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氰乙基对几种芳胺结构和光谱的影响 被引量:2
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作者 唐智勇 胡云楚 +1 位作者 赵莹 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2009年第4期701-706,共6页
采用量子化学中密度泛函理论(DFT)的B3LYP方法分别用6-31G*和6-311+G*基组对苯胺、对氯苯胺和对甲苯胺及其氰乙基衍生物的几何构型进行全优化,探讨了氨基上氰乙基的引入对分子电荷转移、前线轨道能量和电子光谱等性质的影响规律.在此基... 采用量子化学中密度泛函理论(DFT)的B3LYP方法分别用6-31G*和6-311+G*基组对苯胺、对氯苯胺和对甲苯胺及其氰乙基衍生物的几何构型进行全优化,探讨了氨基上氰乙基的引入对分子电荷转移、前线轨道能量和电子光谱等性质的影响规律.在此基础上采用含时密度泛函方法(TD-DFT)计算了分子第一激发态的电子跃迁能,得到最大吸收波长λmax.计算结果表明,氨基上氰乙基的引入,对前线分子轨道组成影响虽然小,但使得最大吸收波长红移,与实验值λmax有较好的一致性,发现该类物质主要吸收光谱源于分子内的π→π*的电子跃迁. 展开更多
关键词 芳胺 氰乙基 密度泛函理论 前线轨道 电子光谱
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用Hirshfeld电荷定量标度亲电性和亲核性:含氮体系(英文) 被引量:4
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作者 周夏禹 荣春英 +1 位作者 卢天 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2014年第11期2055-2062,共8页
准确预测化学过程中分子内各原子提供或接受电子的能力以及化学反应可能的位点,即定量确定亲电性、亲核性和区域选择性,是一个十分重要却仍然亟待解决的课题.此前,基于我们新近提出的信息守恒原理,曾建议使用Hirshfeld电荷和信息增益作... 准确预测化学过程中分子内各原子提供或接受电子的能力以及化学反应可能的位点,即定量确定亲电性、亲核性和区域选择性,是一个十分重要却仍然亟待解决的课题.此前,基于我们新近提出的信息守恒原理,曾建议使用Hirshfeld电荷和信息增益作为两个等价的描述符用于此目的.我们的这个想法已经被成功地应用于两个系列的分子体系,且其有效性得到了充分的验证.然而,先前我们只考察了碳元素的这些性质,所以其结论的普遍性仍存在疑问.我们尚不清楚它是否适用于其他元素,而且对于同一元素的不同价态该结论是否适用也不清楚.为此,本文将考察含氮体系.对5个不同类别的含氮体系共计40个分子进行了研究,其中包括重氮苯、偶氮、重氮、一级和二级胺体系.结果表明,对所有五个含氮体系其Hirshfeld电荷与实验得到的亲电性和亲核性标度之间仍然存在着较强的线性关联.然而,这些相关性却依赖于氮元素的化合价类型和键合环境.该线性关系只能在同一类型中成立.我们对其可能的原因进行了讨论. 展开更多
关键词 Hirshfeld电荷 信息增益 亲电性 亲核性 区域选择性
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顺式效应的起源:双取代乙烯衍生物的密度泛函理论研究(英文) 被引量:6
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作者 赵东波 荣春英 +3 位作者 苏曼 苏文 尹笃林 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2013年第1期43-54,共12页
一般情况下双取代乙烯衍生物的反式构象要比顺式构象稳定.但是例外也存在,例如1,2-二氟乙烯和1,2-二氯乙烯.这种双取代乙烯衍生物顺式构象的超常稳定性被称之为顺式效应.该效应的起源和本质目前仍没有定论.本文以12个体系(XHC=CHY(X,Y=F... 一般情况下双取代乙烯衍生物的反式构象要比顺式构象稳定.但是例外也存在,例如1,2-二氟乙烯和1,2-二氯乙烯.这种双取代乙烯衍生物顺式构象的超常稳定性被称之为顺式效应.该效应的起源和本质目前仍没有定论.本文以12个体系(XHC=CHY(X,Y=F,Cl,Br,CN,CH3,C2H6,OCH3))为例,对顺式效应的有效性、起源和本质进行系统的密度泛函理论研究,其中9个体系存在顺式效应,另外3个为正常体系没有该效应.采用一系列泛函和基组研究其有效性,并运用四种分析手段,如自然键轨道(NBO)、能量分量分析(EDA)、密度泛函活性理论(DFRT)和非共价相互作用(NCI)分析,剖析该效应的起源和本质.发现在顺式构象的两个取代基之间存在一种微弱的非共价相互吸引作用.能量分析表明,静电效应、立体效应等对顺式效应的存在都起着重要作用,但是它们均不能单独用来解释顺式效应的起源.也就是说顺式效应没有一个简单的起源,它是多种作用合力的结果.本文采用双变量解释得到比较合理的相关回归系数R2=0.86-0.87,较好地解释了顺式效应的本质和起源. 展开更多
关键词 密度泛函理论 顺式效应 自然键轨道分析 立体效应 非共价相互作用
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水团簇构象稳定性起源和本质的密度泛函理论与量子分子动力学研究(英文) 被引量:4
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作者 王友娟 赵东波 +1 位作者 荣春英 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2013年第10期2173-2179,共7页
寻找确定分子体系构象稳定性的关键因素是至关重要的,但即使对最简单的分子,其稳定性的起源和本质仍存在很大的争议.本文以水团簇为例,采用量子分子动力学产生185个八聚水分子团簇模型,并运用基于密度泛函理论的两个能量分解方法寻找其... 寻找确定分子体系构象稳定性的关键因素是至关重要的,但即使对最简单的分子,其稳定性的起源和本质仍存在很大的争议.本文以水团簇为例,采用量子分子动力学产生185个八聚水分子团簇模型,并运用基于密度泛函理论的两个能量分解方法寻找其稳定性的决定因素.我们发现不同水团簇的稳定性与其立体排斥能和交换相关能成良好的线性关系.本文还采用双变量模型模拟水团簇的稳定性,取得了更好的结果(相关系数大于0.99).本工作对揭示包括水分子团簇在内的通过弱相互作用组成的分子络合物的稳定性起源和本质提供了有益启示. 展开更多
关键词 水分子团簇 量子分子动力学 密度泛函理论 立体效应 交换相关能
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概念密度泛函理论及近来的一些进展 被引量:62
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作者 刘述斌 《物理化学学报》 SCIE CAS CSCD 北大核心 2009年第3期590-600,共11页
概念密度泛函理论(又称密度泛函活性理论或化学密度泛函理论)是密度泛函理论(DFT)的化学活性理论.本文对其理论框架和最新进展进行了概述,包括电负性、硬度、软度、福井函数、亲电性,及其从这些概念中得到的原理.介绍了二元描述符和立... 概念密度泛函理论(又称密度泛函活性理论或化学密度泛函理论)是密度泛函理论(DFT)的化学活性理论.本文对其理论框架和最新进展进行了概述,包括电负性、硬度、软度、福井函数、亲电性,及其从这些概念中得到的原理.介绍了二元描述符和立体效应定量描述的新进展,并对今后的发展作出了展望. 展开更多
关键词 概念密度泛函理论 电负性 硬度 软度 福井函数 亲电性 二元描述符 立体效应
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