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A novel direct reduction method to synthesize ordered Fe-pt alloy nanoparticles

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journal of Materials Science & Technology 2019年第4期35卷 560-567页

作者： q.Zheng Z.R.Zhang j.Du L.L.Lin W.X.Xia j.Zhang B.R.Bian j.p.Liu School of Materials and Chemical Engineering Ningbo University of Technology CAS Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology & EngineeringChinese Academy of Sciences Department of physics University of Texas at Arlington

In this work, a direct green solid-phase reduction method for the fabrication of large yield of ordered phase Fe-pt alloy nanoparticles was reported, in which inorganic salts were used as metal precursors and H_2-containing atmosphere was used as reducer. Utilizing this method, the composition and chemical ordered phase, such as L1_2-Fe_3 pt, L1_2-Fept_3, and L1_0-Fept phases can be easily achieved by one step reaction. The synthesized nanoparticles have clean surface because no organic precursors, no organic solutions or organic surfactants/ligands were used. Their magnetic performance and the formation mechanism of Fe-pt alloy nanoparticles were also investigated. This strategy can be applied to synthesize many other types of alloy nanoparticles with desired composition and necessary crystal structure, which can be used for a variety of practical applications, such as in magnetism and catalyst research fields.

关键词： Magnetic nanoparticles Fept Chemical synthesis

FREEZE pROFILE AND HEAT BALANCE CALCULATION OF THE 160kA DRAINED CELL

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Acta Metallurgica Sinica(English Letters) 2004年第2期17卷 215-220页

作者： X.p. Li j. Li Y.q. Lai H.q.Zhao Y.X.Liu School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China Sch. of Metall. Sci. and Eng. Central South Univ. Changsha 410083 China

A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its heat balance was calculated. Comparedwith that of a 160kA conventional Hall-Heroult cell (H-H cell), though the melts vol-ume of the drained cell reduced greatly, the whole heat loss from it didn't drop downapparently, and an analysis was presented in the paper. On the other hand, the anode-cathode distance (ACD) of a drained cell was much less than that of a H-H cell, sothe voltage drop on it and heat produced decreased too, steps should be taken to keepa workable heat balance on a drained cell.

关键词： drained cell freeze profile heat balance finite element code

Convexification of Hybrid AC-DC Optimal power Flow with Line-Commutated Converters

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CSEE journal of power and Energy Systems 2024年第2期10卷 617-628页

作者： Hongyuan Liang Zhigang Li j.H.Zheng q.H.Wu School of Electric power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (HVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OpF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OpF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OpF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

An in-vitro Investigation of Iron-Containing Hydroxyapatite/Titanium Composites

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journal of Materials Science & Technology 2011年第6期27卷 546-552页

作者： q. Chang H.q. Ru D.L. Chen X.Y. Yue L. Yu C.p. Zhang Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education) Northeastern University Shenyang 110004 China Department of Mechanical and Industrial Engineering Ryerson University 350 Victoria Street Toronto Ontario M5B 2K3 Canada

The in-vitro biological behavior of a newly-developed iron-containing hydroxyapatite/titanium（HA/Ti） composite was investigated by immersing the composites in the simulated body fluid（SBF） for up to 5 *** addition of iron was observed to have a significant influence on the in-vitro biological behavior of the *** obtained results revealed that the stability of the composites in the physiological solution was markedly *** solubility decreased in the order of pure HA,HA/5（Ti-33Fe）,and HA/15（Ti33Fe）.precipitation occurred on the surface of HA/5（Ti-33Fe） composite,showing a good combination of physiostability with bioactivity,while HA/15（Ti-33Fe） composite exhibited superior physiostability since there was no obvious change on the surface of HA/15（Ti-33Fe）.

关键词： Hydroxyapatite composite Iron Titanium Simulated body fluid Biological behavior

Harmonic balance-based approach for optimal time delay to control unstable periodic orbits of chaotic systems

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Acta Mechanica Sinica 2020年第4期36卷 918-925页

作者： Y.M.Chen q.X.Liu j.K.Liu Department of Mechanics Sun Yat-sen UniversityGuangzhou 510275China

As a classical technique for chaos suppression,the time-delayed feedback controlling strategy has been widely developed by stabilizing unstable periodic orbits(UpOs)embedded in chaotic systems.A critical issue for achieving high controlling precision is to search for an appropriate time *** paper proposes a simple yet effective approach,based on incremental harmonic balance method,to determine the optimal time delay in the delayed feedback *** time delay is adjusted within the iterative scheme provided by the proposed method,and finally converges to the period of the target *** long as the optimal time delay is fixed,moreover,the attained solution makes it quite convenient to analyze its stability according to the Floquet theory,which further provides the effective interval of the feedback gain.

关键词： Chaos control Unstable periodic orbit Delayed feedback Optimal time delay Incremental harmonic balance method

A MODIFIED BISECTION SIMpLEX METHOD FOR LINEAR pROGRAMMING

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journal of Computational Mathematics 1996年第3期14卷 249-255页

作者： p.q. pan(Department of Mathematics and Mechanics, Southeast University, Nanjing China) 东南大学数力系江苏南京

In this paper, a modification of the bisection simplex method([7]) is made for more general purpose use. Organized in an alternative simpler form, the modified version exploits information of the optimal value, as does the original bisection method, but no bracket on the optimal value is needed as part of input; in stead, it only requires provision of an estimate b(0) of the optimal value and an estimate of the error bound of b(0) (it is not sensitive to these values though). Moreover, a new, ratio-test-free pivoting rule is proposed, significantly reducing computational cost at each iteration. Our numerical experiments show that the method is very promising, at least for solving linear programming problems of such sizes as those tested.

关键词：二等分法最佳值线性编程问题

Dispatchable Region for Active Distribution Networks Using Approximate Second-order Cone Relaxation

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CSEE journal of power and Energy Systems 2023年第6期9卷 1999-2007页

作者： Zhigang Li Wenjing Huang j.H.Zheng q.H.Wu School of Electric power Engineering South China University of TechnologyGuangzhou 510640China

Uncertainty in distributed renewable generation threatens the security of power distribution *** concept of dispatchable region is developed to assess the ability of power systems to accommodate renewable generation at a given operating *** DC and linearized AC power flow equations are typically used to model dispatchable regions for transmission systems,these equations are rarely suitable for distribution *** achieve a suitable trade-off between accuracy and efficiency,this paper proposes a dispatchable region formulation for distribution networks using tight convex *** cone relaxation is adopted to reformulate AC power flow equations,which are then approximated by a polyhedron to improve ***,an efficient adaptive constraint generation algorithm is employed to construct the proposed dispatchable *** studies on distribution systems of various scales validate the computational efficiency and accuracy of the proposed method.

关键词： Dispatchable region distribution system renewable power generation second-order cone relaxation uncertainty

Experimental study of the effect of wear parameters on the wear behavior of A356 alloy/cow horn particulate composites

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Defence Technology（防务技术） 2018年第1期14卷 77-82页

作者： B.q.Ochieze C.C.Nwobi-Okoye p.N.Atamuo Lafarge Africa plc Mfamosing Plant Department of Mechanical Engineering Chukwuemeka Odumegwu Ojukwu University

Experimental study of the effect of wear parameters on the wear behaviour of A356 alloy reinforced with cow horn particles(CHp) produced by spark plasma sintering was investigated. Experiments were conducted based on the plan of experiments generated through Taguchi's(L9) technique. Tribometer was used for the wear test and Scanning electron microscope was used to analyse the worn scar of the samples. The results shows that, A356 alloy reinforced with CHp exhibited better dry sliding wear resistance than the unreinforced alloy. Wear rate decreased as the amount of CHp reinforcement increased in the matrix. It was found that, the optimum level of the factors with minimized the wear loss were obtained at: wt%CHp(20%), applied load(10 N), sliding velocity(3 m/s) and sliding distance(2000 m). It can be seen that the wear track of the sample are(D ? 0.81 and L = 42.85 mm) and(D ? 0.54 and L= 27.03 mm) for A356 alloy and composites at optimum condition respectively. The results showed that the addition of cow horn particles as reinforcing materials in A356 alloy composites increased the wear resistance of the composites greatly.

关键词： A356alloy Cow horn particles Microstructure Analysis of variance and wear behaviour

Mechanical properties and Defective Effects of 316LN Stainless Steel by First-principles Simulations

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journal of Materials Science & Technology 2011年第11期27卷 1029-1033页

作者： X.q. Li j.j. Zhao j.C. Xu X. Liu Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education Dalian University of Technology Dalian 116024 China College of Advanced Science and Technology Dalian University of Technology Dalian 116024 China School of Chemical Engineering Dalian University of Technology Dalian 116024 China

In current International Thermonuclear Experimental Reactor （ITER） design, the 316LN austenitic stainless steel （316LN SS） is used for first-wall/blanket structures. Thus, it is necessary to study the fundamental mechanical properties and irradiation effect of 316LN SS. A random solid solution model of Fe-Cr-Ni-Mn- Mo-Si alloy is used for describing 310LN S$. Using first-principles approaches, the elastic constants and ideal strength of the alloy were calculated. Such alloy exhibits good ductile behavior according to the theoretical values of Cauchy pressure and ratio of bulk modulus and shear modulus. Within the 256-atom supercell, inclusion of single vacancy defect further enhances the ductility of the alloy, and the existence of interstitial （Fe, H, He） atoms enhances the Young＇s modulus.

关键词： Stainless steel Mechanical properties Vacancy Interstitial