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On the Preconditioning Properties of RHSS Preconditioner for Saddle-Point Linear Systems

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Communications on Applied Mathematics and Computation 2021年第1期3卷 177-187页

作者： ju-Li zhang School of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201620China

In this paper,for the regularized Hermitian and skew-Hermitian splitting(RHSS)preconditioner introduced by Bai and Benzi(BIT Numer Math 57:287–311,2017)for the solution of saddle-point linear systems,we analyze the spectral properties of the preconditioned matrix when the regularization matrix is a special Hermitian positive semidefinite matrix which depends on certain *** accurately describe the numbers of eigenvalues clustered at(0,0)and(2,0),if the iteration parameter is close to *** estimate about the condition number of the corresponding eigenvector matrix,which partly determines the convergence rate of the RHSS-preconditioned Krylov subspace method,is also studied in this work.

关键词： Saddle-point linear systems RHSS preconditioner Preconditioning properties Matrix similar transformation Condition number of eigenvector matrix

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弹性网络正则化的高维序列因果关联识别研究

华北理工大学学报（自然科学版） 2025年第1期47卷 96-105页

作者：张居营安风楼河北金融学院金融与投资学院河北保定071051 太平洋证券股份有限公司北京100033

弹性网络正则化方法兼顾了L1正则化与L2正则化的优点,能够解决高维时间序列因果关系分析中共线性、过度拟合与信息冗余等问题,有效发掘高维序列之间的主要关联关系。首先,基于VAR模型与长期格兰杰因果关联网络,阐述高维序列因果关联识... 详细信息

弹性网络正则化方法兼顾了L1正则化与L2正则化的优点,能够解决高维时间序列因果关系分析中共线性、过度拟合与信息冗余等问题,有效发掘高维序列之间的主要关联关系。首先,基于VAR模型与长期格兰杰因果关联网络,阐述高维序列因果关联识别的方法;其次,讨论了弹性网络正则化如何解决高维序列因果关系建模的弊端,融合L1与L2正则化的主要特点;最后,结合多维大宗商品期货价格日度波动率序列,探索了弹性网络正则化在高维序列因果关联识别的应用,并与其他正则化方法进行比较。结果表明,弹性网络正则化方法避免了信息冗余与“过度稀疏化”的问题,识别与提炼商品价格波动因果关联网络中的主要影响节点与传导关系,挖掘序列关系网络中的主要因果关联。

关键词：弹性网络正则化高维序列长期格兰杰因果关联网络

Effects of additives on the phase transformation, occurrence state, and the interface of the Ti component in Ti-bearing blast furnace slag

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International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 1029-1040页

作者： Li zhang Wu zhang ju-hua zhang Guang-qiang Li School of Materials and Metallurgy Northeastern University School of Materials Science and Engineering Shenyang Ligong University School of Materials and Metallurgy Wuhan University of Science and Technology

The influences of additives on the phase transformation, occurrence state, and the interface of the Ti component in Ti-bearing blast furnace slag were investigated. After oxidation, most of the Ti component in the slag was enriched into the perovskite phase, which served as the Ti-rich phase during the crystallization process. The phase transformation, occurrence state, and the interface of the Ti component were observed to be affected by the addition of different types of agents. During the oxidation process, titanaugite and Ti-rich diopside phases gradually transformed into non-Ti phases（anorthite： CaMgSi2O6 and CaAl2Si2O8） in the form of dendrites or columns, which were observed to be distributed at the surface of the perovskite phase. Several more cracks appeared along the grain boundaries of the perovskite phase after the addition of P2O5, facilitating the liberation of the perovskite phase. Composite additives combining both an acid and a base, such as CaO ＋ CaF2 or P2O5 ＋ CaF2, were used. We observed that the disadvantages of using single additives were successfully overcome.

关键词： blast furnace slag titanium additives phase transformation interfaces

Proposition of atomic and close-to-atomic scale manufacturing

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Advances in Manufacturing 2024年第1期12卷 1-5页

作者： ju‑Fan zhang Jens Ducree School of Mechanical and Materials Engineering University College DublinDublin 4Ireland School of Physical Sciences Dublin City UniversityDublinIreland

Atomic and close-to-atomic scale manufacturing(ACSM)is the core competence of Manufacturing *** other conceptions or terminologies that only focus on the atomic level precision,ACSM defnes a new realm of manufacturing where quantum mechanics plays the dominant role in the atom/molecule addition,migration and removal,considering the uncertainty principle and the discrete nature of *** ACSM is still in its infant stage,only little has been systematically elaborated at the core proposition of ACSM by now,hence there is a need to understand its concept and *** article elucidates the development of ACSM and clarifes its proposition,which aims to achieve a clearer understanding on ACSM and direct more efective eforts toward this promising area.

关键词： Atomic and close-to-atomic scale manufacturing(ACSM) Atomic Precision Manufacturing Paradigm Manufacturing III

Coordinating Pricing and Inventory Control in a Fluctuating Environment

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Acta Mathematicae Applicatae Sinica 2010年第2期26卷 187-204页

作者： ju-liang zhang Jian Chen Xiang-sun zhang Department of Logistics Management School of Economics and Management Beijing Jiaotong UniversityBeijing 100044 China Department of Management Science and Engineering School of Economics and Management Tsinghua Uni-versity Beijing 100084 China Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sci-ences Beijing 100190 China

This paper addresses the simultaneous determination of pricing and inventory replenishment strate- gies under a fluctuating environment. Specifically, we analyze the single item, periodic review model. The demand consists of two parts： the deterministic component, which is influenced by the price, and the stochastic component （perturbation）. The distribution of the stochastic component is determined by the current state of an exogenous Markov chain. The price that is charged in any given period can be specified dynamically. A replenishment order may be placed at the beginning of some or all of the periods, and stockouts are fully backlogged. Ordering costs that are lower semicontinuous, and inventory/backlog （or surplus） costs that are continuous with polynomial growth. Finite-horizon and infinite-horizon problems are addressed. Existence of optimal policies is established. Furthermore, optimality of （s,S,p）-type policies is proved when the ordering cost consists of fixed and proportional cost components and the surplus cost （these costs are all state-dependent） is convex.

关键词： Stochastic inventory management Markov chains pricing finite horizon infinite horizon

Structures and Electronic Properties of Cu_N (N≤13) Clusters

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Communications in Theoretical Physics 2009年第10期52卷 675-680页

作者： FENG Cui-ju zhang Xiao-Yan Department of Basic Courses North China Institute of Science and Technology Beijing 101601 China

A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copper clusters. Our results show that the three-dimensional isomers of copper clusters start from Cu7 cluster and then show a tendency to form more compact structures. The results of the formation energy and the second derivative of binding energy with duster size show that besides N = 8, N =11 is also a magic number. Furthermore, it is the first time to find that the ground state of 11-atom clusters is a biplanar structure as same as the 13-atom cluster. The clear odd-even alternation as cluster size for the formation energy indicates the stability of electronic close shell existed in the range studied.

关键词： first-principles calculations density functional for molecules copper clusters

CO Clouds around SNR G21.8-0.6 and G32.8-0.1

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 705-711页

作者： Jian-jun Zhou Xi-Zheng zhang Hong-Bo zhang Jarken Esimbek ju-Yong zhang Bing-Gang ju National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 National Astronomical Observatories / Urumqi Observatory Chinese Academy of Sciences Urumqi 830011 Graduate School of Chinese Academy of Sciences Beijing 100049 Qinghai Station of Purple Mountain Observatory Chinese Academy of Sciences Delingha 817000

We made the first CO（1-0） mapping to SNR G21.8-0.6 and SNR G32.8-0.1, both associated with OH 1720MHz maser. Based on the morphological correspondence and velocity and position agreement between the radio remnant an... 详细信息

关键词： ISM clouds -- ISM individual (G21.8-0.6, G32.8-0.1 ) -- ISM molecules -- masers -- supernova remnants

Ambient air quality trends and driving factor analysis in Beijing, 1983–2007

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Journal of Environmental Sciences 2011年第12期23卷 2019-2028页

作者： ju zhang Zhiyun Ouyang Hong Miao Xiaoke Wang State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

The rapid development in Beijing, the capital of China, has resulted in serious air pollution problems. Meanwhile great efforts have been made to improve the air quality, especially since 1998. The variation in air quality under the interaction of pollution and control in this mega city has attracted much attention. We analyzed the changes in ambient air quality in Beijing since the 1980’s using the Daniel trend test based on data from long-term monitoring stations. The results showed that different pollutants displayed three trends： a decreasing trend, an increasing trend and a flat trend. SO2, dustfall, B[a]P, NO2 and PM10 fit decreasing trend pattern, while NOx showed an increasing trend, and CO, ozone pollution, total suspended particulate （TSP）, as well as Pb fit the flat trend. The cause of the general air pollution in Beijing has changed from being predominantly related to coal burning to mixed traffic exhaust and coal burning related pollution. Seasonally, the pollution level is typically higher during the heating season from November to the following March. The interaction between pollution sources change and implementation of air pollution control measures was the main driving factor that caused the variation in air quality. Changes of industrial structure and improved energy effciency, the use of clean energy and preferred use of clean coal, reduction in pollution sources, and implementation of advanced environmental standards have all contributed to the reduction in air pollution, particularly since 1998.

关键词： ambient air quality trend analysis driving factor particulate matter

In vitro evaluation of artificial joints: a comprehensive review

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Advances in Manufacturing 2019年第1期7卷 1-14页

作者： Gang Shen ju-Fan zhang Feng-Zhou Fang Centre of Micro/Nano Manufacturing Technology (MNMTDublin) University College Dublin Dublin Ireland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology (MNMT) Tianjin University Tianjin 300072 People's Republic of China

Development of artificial joints is a great progress for joint replacement operations of human being, but the short longevity of prostheses has concerned both industries and researchers since the advent of modem implants. Thus, continuous improvements have been made alongside the clinical applications. The methodologies to inspect the potential properties of new designs have also seen many advances. The test machines have evolved from easy pin-on-disk configuration to the modem joint simulator. Besides, various wear traces provided by testing machines are investigated greatly, and multi-directional files are recommended as motion profiles for in vitro testing. The typical testing parameters, like sliding speed or loading profile, are discussed in this article, and their working mechanisms are described in detail. Meanwhile, the calf or bovine serum has been regarded as the gold standard for testing lubricant, and the future trend of fluid will be focused on investigating the effects of lubricant composites on the tribological properties. Hard particles and proteins are discussed as well, and their effects on the wear mechanisms are the focus. Finally, various approaches to measure the wear rate, wear factor and the thickness of lubricant film are presented, and suggestions are given for the development in future.

关键词： Artificial joint Methodology Testing parameter Wear rate