检索结果-南通市图书馆

Parameterized Post-Post-Newtonian Light Propagation in the Field of One Spherically-Symmetric Body

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2019年第12期71卷 1455-1460页

作者： Xiao-Yan Zhu Bo Yang chun-hua jiang Wen-Bin Lin School of Mathematics and Physics University of South ChinaHengyang 421001China School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China

We derive a more generally parameterized post-post-Newtonian solution for the light propagation in the gravitational field of one spherically-symmetric *** on the solution for the light velocity,we give the formula of the light deflection when both the emitter and receiver are located in the regions far away from the body,which is the most important scenario in the real *** results can be applied to more metric theories of gravitation.

关键词： PPN spherically-symmetric metric light propagation light deflection

Mechanism of local solidification time variations with melt rate during vacuum arc remelting process of 8Cr4Mo4V high-strength steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第2期31卷 377-388页

作者： Tao Pan Hong-chun Zhu Zhou-hua jiang hua-bing Li Rui Zhang Hao Feng School of Metallurgy Northeastern UniversityShenyang110819LiaoningChina State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819LiaoningChina

A 2D axisymmetric numerical model was established to investigate the variations of molten pool with different melt rates during the vacuum arc remelting of 8Cr4Mo4V high-strength steel,and the ingot growth was simulated by dynamic mesh *** results show that as the ingot grows,the molten pool profile changes from shallow and flat to V-shaped,and both the molten pool depth and the mushy width ***,the variation of both the molten pool shape and the mushy width melt rate is clarified by the thermal equilibrium *** melt rate increases,both the molten pool depth and the mushy width *** is caused by the increment in sensible heat stored in the ingot due to the limitation of the cooling capacity of the *** nonlinear increment in sensible heat leads to a nonlinear increase in the mushy *** addition,as melt rate increases,the local solidification time(LST)of ingot decreases obviously at first and then *** melt rate is controlled in a suitable range,LST is the lowest and the secondary dendrite arm spacing of the ingot is the smallest,which can effectively improve the compactness degree of 8Cr4Mo4V high-strength steel.

关键词： 8Cr4Mo4V high-strength steel Vacuum arc remelting process Melt rate Molten pool Local solidification time

The dynamics beamline at SSRF

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第9期35卷 56-67页

作者： Zhen Liu Li-hua Wang Yong jiang Ya-Jun Tong hua-chun Zhu Te Ji Min Chen Zheng jiang Xiang-Jun Wei Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China ShanghaiTech University Shanghai 201210China

The dynamics beamline(D-Line),which combines synchrotron radiation infrared spectroscopy(SR-IR)and energy-disper-sive X-ray absorption spectroscopy(ED-XAS),is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved *** combined technique is effective for investigating rapid structural changes in atoms,electrons,and molecules in complicated disorder systems,such as those used in physics,chemistry,materials science,and extreme ***,ED-XAS and SR-IR can be used independently in the two branches of the *** ED-XAS branch is the first ED-XAS beamline in China,which uses a tapered undulator light source and can achieve approximately 2.5×10^(12)photons/s·300 eV BW@7.2 keV at the sample *** exchange-able polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy *** focused beam size is approximately 3.5μm(H)×21.5μm(V),and the X-ray energy range is 5–25 *** one-and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be *** distinctive techniques,such as the concurrent measurement of in situ ED-XAS and infrared spectroscopy,time-resolved ED-XAS,high-pressure ED-XAS,XMCD,and pump-probe ED-XAS,can be applied to achieve different scientific goals.

关键词： ED-XAS SR-IR Time-resolved D-line SSRF

A Practical Parallel Algorithm for All-Pair Shortest Path Based on Pipelining

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology of China 2008年第3期6卷 329-333页

作者： hua Wang Ling Tian chun-hua jiang School of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu 610054 China

On the basis of Floyd algorithm with the extended path matrix, a parallel algorithm which resolves all-pair shortest path （APSP） problem on cluster environment is analyzed and designed. Meanwhile, the parallel APSP pipelining algorithm makes full use of overlapping technique between computation and communication. Compared with broadcast operation, the parallel algorithm reduces communication cost. This algorithm has been implemented on MPI on PC-cluster. The theoretical analysis and experimental results show that the parallel algorithm is an efficient and scalable algorithm.

关键词： All-pair shortest path Floyd algorithm pipelining parallel algorithm

A New Solution to Intrusion Detection Systems Based on Improved Federated-Learning Chain

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第6期79卷 4491-4512页

作者： chunhui Li hua jiang School of Computer and Electronic Information Guangxi UniversityNanning530000China Cyber Security and Information Center Guangxi UniversityNanning530000China

In the context of enterprise systems,intrusion detection(ID)emerges as a critical element driving the digital transformation of *** systems spanning various sectors of enterprises geographically dispersed,the necessity for seamless information exchange has surged *** existing cross-domain solutions are challenged by such issues as insufficient security,high communication overhead,and a lack of effective update mechanisms,rendering them less feasible for prolonged application on resource-limited *** study proposes a new cross-domain collaboration scheme based on federated chains to streamline the server-side *** this framework,individual nodes solely engage in training local data and subsequently amalgamate the final model employing a federated learning algorithm to uphold enterprise systems with efficiency and *** curtail the resource utilization of blockchains and deter malicious nodes,a node administration module predicated on the workload paradigm is introduced,enabling the release of surplus resources in response to variations in a node’s contribution *** encountering an intrusion,the system triggers an alert and logs the characteristics of the breach,facilitating a comprehensive global update across all nodes for collective *** results across multiple scenarios have verified the security and effectiveness of the proposed solution,with no loss of its recognition accuracy.

关键词： Cross-domain collaboration blockchain federated learning contribution value node management release slack resources

Finite-time composite learning control for nonlinear teleoperation systems under networked time-varying delays

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第6期67卷 279-296页

作者： Yana YANG Huixin jiang Changchun hua Junpeng LI Institute of Electrical Engineering Yanshan University

The robust finite-time synchronization control problem is investigated for master-slave networked nonlinear telerobotics systems(NNTSs) in this article. Although there have been some research achievements on finite-time control for the NNTSs, these studies are based on the strong assumptions of communication time delays or can only achieve finite-time bounded convergence even when the external forces are *** and in view of the importance of these issues, a novel robust composite learning adaptive control scheme rendering the finite-time master-slave synchronization is proposed in this paper. In particular, the influence of time delays on finite-time convergence of the system is analyzed by employing the multi-dimension finite-time small-gain framework. Meanwhile, in order to achieve accurate and fast estimation of uncertain parameters of the system, both the online historical and the instantaneous data of the estimation data are explored to derive the new parameter adaptive law under a more realizable interval-excitation(IE) ***, the convergence of the position/force synchronization errors and the adaptive parameter estimation errors is obtained in finite time, and enhanced robustness of the closed-loop system will also be ***, the superior performance of the proposed control algorithms is validated by numerical simulations and hardware experiments.

关键词： networked teleoperation systems finite-time control exact parameter estimation small-gain theorem unknown communication delays

Optimal investment based on relative performance and weighted utility

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 328-342页

作者： WANG Lei DONG Ying-hui hua chun-rong Department of Mathematics Suzhou University of Science and TechnologySuzhou 215009China Changshu Institute of Technology Changshu 215500China

This paper studies the optimal portfolio allocation of a fund manager when he bases decisions on both the absolute level of terminal relative performance and the change value of terminal relative performance comparison to a predefined reference point. We find the optimal investment strategy by maximizing a weighted average utility of a concave utility and an Sshaped utility via a concavification technique and the martingale method. Numerical results are carried out to show the impact of the extent to which the manager pays attention to the change of relative performance related to the reference point on the optimal terminal relative performance.

关键词： relative performance weighted utility S-shaped utility concavification

Cretaceous magmatic arc in Hainan and the peri-South China Sea asevidenced by geochemical fingerprinting of granitoids in the region

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2024年第5期15卷 355-371页

作者： Xiao-Yan jiang Yildirim Dilek Xian-hua Li State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Department of Geology and Environmental Earth Science Miami UniversityOxfordOH 45056USA

Mesozoic magmatic rocks occur widely in the South China Block and are generally interpreted as the manifestations of the subduction of the Paleo-Pacific oceanic lithosphere beneath *** magmatism in southeast(SE)China continued from the Late Permian through the Late Cretaceous with an inferred lull between 125 Ma and 115 Ma that is known in the literature as the Cretaceous"magmatic quiescence".We report in-situ zircon U-Pb ages,Hf-O and whole-rock Sr-Nd isotopes,and whole-rock geochemistry of Cretaceous granitoids on Hainan Island and discuss their magmatic evolution within the framework of the Late Mesozoic geodynamics of SE *** recognize two main stages of the emplacement of Cretaceous granitoids on Hainan,first around 120 Ma and then around 100-95 Ma,displaying high-K calc-alkaline,I-type geochemical *** in both age groups are enriched in LILE and LREE,but depleted in Nb,Ta,Ba,Sr,and *** 120 Ma granites have zircon ε_(Hf)(t)values of-2.6 to 2.3 corresponding to Hf crustal model ages,ranging from 0.79 Ga to 1.03 Ga,and δ^(18)O values ranging from 6.9‰to 7.7‰.Zircons from 100-95 Ma granites have ε_(Hf)(t)values of-4.2 to 1.1 corresponding to Hf crustal model ages of 1.08 Ga to 1.42 Ga,and δ^(18)O values ranging from 6.7‰to 8.4‰.Increasing ε_(Hf)(t)values of the Cretaceous Hainan granites with younger crystallization ages indicate addition of more juvenile components and reworking of crustal material into their melt *** ε_(Nd)(t)values of the 120 Ma and 100-95 Ma granitoids range between-4.1 to-0.4 and-7.7 to-4.0,*** calculated two-stage model age of the 100-95 Ma granitoids clusters between 1.25 Ga and 1.53 *** isotopic data suggest that magmas of the Cretaceous granitoids were produced by partial melting of Mesoproterozoic metabasaltic rocks,which make up much of the crystalline basement of the southern Cathaysia *** geochemical and isotopic characteristics of the Cretaceous granitoids on H

关键词： I-type granites Cretaceous Hainan Island Southeast China Magmatic arc peri-South China Sea region

The Limitations and Ethical Considerations of ChatGPT

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Data Intelligence 2024年第1期6卷 201-239页

作者： Shangying hua Shuangci Jin Shengyi jiang Guangdong University of Foreign Studies Guangzhou 510000China

With the advancements of artificial intelligence technology,ChatGPT,a new practice of artificial intelligence,holds immense potential across multiple *** user-friendly human-machine interface,rapid response capabilities,and delivery of high-quality answers have attracted considerable attention and widespread *** by many as a groundbreaking advancement in AI,ChatGPT represents a new milestone in the ***,as with any technological evolution,the emergence of ChatGPT brings not only benefits,but also inevitable security risks and ethical *** paper provides specific information about ChatGPT,including its technology,limitations,ethical issues,governance paths and future ***,we firstly offered a thorough exploration of the technical implementation details of GPT series ***,we provided an intricate analysis elucidating the reasons for limitations and scrutinized the consequential impacts,such as malicious misuse,privacy violation,and so ***,we explore diverse governance paths to mitigate the impacts of ChatGPT and present future *** review aims to equip users with crucial knowledge,facilitating well-informed decision-making,effectively handling of potential challenges in employing ChatGPT,and staying abreast with the rapidly evolving landscape of this technology.

关键词： ChatGPT ChatGPT Technology Limitations Ethical considerations Artificial Intelligence