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Communication Resources Allocation for Time Delay Reduction of Frequency Regulation Service in High Renewable Penetrated Power System

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 468-480页

作者： Hongjie He Ning Zhang chongqing Kang Song Ci Fei Teng Goran Strbac State Key Laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Department of Electrical and Electronic engineering Imperial College LondonSW72BULondonU.K

The high renewable penetrated power system has severe frequency regulation *** resources can provide frequency regulation services but are limited by com-munication time *** paper proposes a communication resources allocation model to reduce communication time delay in frequency regulation *** device resources and wireless spectrum resources are allocated to distributed resources when they participate in frequency *** reveal impact of communication resources allocation on time delay reduction and frequency regulation ***,we study communication resources allocation solution in high renewable energy penetrated power *** provide a case study based on the HRP-38 *** show communication time delay decreases distributed resources'ability to provide frequency regulation *** the other hand,allocating more communication resources to distributed resources'communica-tion services improves their frequency regulation *** power systems with renewable energy penetration above 70%,required communications resources are about five times as many as 30%renewable energy penetrated power systems to keep frequency performance the *** Terms-Communication resources allocation,commun-ication time delay,distributed resource,frequency regulation,high renewable energy penetrated power system.

关键词： Communication resources allocation communication time delay distributed resource frequency regulation high renewable energy penetrated power system

Single-atom Ni-N_(4) for enhanced electrochemical sensing

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Nano Research 2024年第8期17卷 7658-7664页

作者： Zhuhui Qin Bo Tang Guiru Zhang chongqing Zhu Kun Jiang Bowei Zhang Fu-Zhen Xuan Shanghai Key Laboratory of Intelligent Sensing and Detection Technology East China University of Science and TechnologyShanghai 200237China Key Laboratory of Pressure Systems and Safety of Ministry of Education East China University of Science and TechnologyShanghai 200237China School of Mechanical and Power engineering East China University of Science and TechnologyShanghai 200237China Key Laboratory of Theoretical and Computational Photochemistry Ministry of EducationCollege of ChemistryBeijing Normal UniversityBeijing 100875China Interdisciplinary Research Center School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Single-atom catalysts(SACs)attract widespread attention in heterogeneous catalysis due to their maximum atomic utilization efficiency and unique physical and chemical ***,their applications in chemical sensing keep huge potential but remain ***,a Ni-N_(4)-C SAC was synthesized for the trace detection of dopamine(DA)and uric acid(UA).The Ni-N_(4)-C SAC exhibited superior sensing performance compared to the Ni *** detection range for DA and UA were 0.05–75μM and 5–90μM with detection limits of 0.027 and 0.82μM,*** functional theory(DFT)computations indicate that Ni-N_(4)-C has a lower reaction barrier during electrochemical process,indicating that the atomic Ni sites possess higher intrinsic activity than Ni ***,DA and UA show strong potential dependency on the Ni-N_(4)-C catalyst,indicating its applicability for their concurrent *** work extends the application of SACs in chemical sensing.

关键词： single-atom catalysts chemical sensing dopamine uric acid

Effect of surface nanocrystallization on the corrosion behavior of Zircaloy-4

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science china(Technological sciences) 2009年第8期52卷 2227-2231页

作者： ZHU YuTao1,2 & ZHANG XiYan1,2,3 1 college of materials science and engineering, chongqing university, chongqing 400045, china 2 National engineering Research Center for Magnesium Alloys, chongqing university, chongqing 400044, china 3 School of Physical science and engineering Technology, Guangxi university, Nanning 530004, china college of materials science and engineering Chongqing University Chongqing China National engineering Research Center for Magnesium Alloys Chongqing University Chongqing China School of Physical science and engineering Technology Guangxi University Nanning China

The contrastive corrosion experiments between surface nanocrystallined Zircaloy-4 and coarse-grained Zircaloy-4 under the condition of 673 K/10.3 MPa in pure water are carried out, and the microstructure of oxide films has been studied. The results indicate that the growth rate of oxide films formed on the nanocrystalline Zircaloy-4 is lower than that of oxide films formed on the coarse-grained Zircaloy-4. Simultaneously, the oxide/metal interface of the former is more regular and glossy than that of the latter. For nanocrystalline Zircaloy-4, the low oxygen diffusion rate through the oxide/metal interface can hinder the reaction of oxygen ion with metal ion. Furthermore, more tetragonal ZrO2 are observed in the oxide films, which can delay the martensite phase transition from tetragonal to monoclinic phase in oxide films.

关键词： nanocrystalline Zircaloy oxide film microstructure

Study on calculation model of road lighting visibility

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science china(Technological sciences) 2010年第7期53卷 1768-1773页

作者： WENG Ji1, HU YingKui2 & YING Wen1 1college of Architecture and Urban Planning, chongqing university, chongqing 400045, china 2college of Civil engineering, chongqing university, chongqing 400045, china college of Architecture and Urban Planning Chongqing University Chongqing China college of Civil engineering Chongqing University Chongqing China

Visibility is an evaluation index for road lighting, which comprehensively influences the vision reliability of drivers and is a key factor for road lighting safety and energy saving. This paper introduces the concept of road lighting visibility and its influencing factors. It also explains the small target visibility calculation model for road lighting design, and describes the significance of establishing urban road lighting visibility standards from a point of view of visual function and visual comfort of drivers.

关键词： road lighting visibility calculation model design standard

Solid reaction mechanism of CaHPO_4·2H_2O + CaCO_3 with and without yttria

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Rare Metals 2009年第1期28卷 77-81页

作者： WANG Yong GAO Jiacheng HU Jinzhu ZHANG Yan college of materials science and engineering Chongqing University Chongqing 400045 China National engineering Research Center for Magnesium Alloys Chongqing University Chongqing 400045 China college of materials science and engineering Southwest University Chongqing 400700 China

The effect of yttria on the solid reaction mechanism of a CaHPO4·2H2O ＋ CaCO3 system at different temperatures was experimentally stud-ied. The samples with and without yttria were subjected to thermogravimetric/differential scanning calorimetry measurement. The samples were heat treated at the temperatures corresponding to the peaks on the DSC spectra, and the resulted phase compositions were identified by X-ray diffraction. The transformation mechanism was deduced by comparing the phases obtained at different temperatures. The results show that the transformations at below 1073 K are not affected by yttria, but all those at above 1073 K are completely altered. The formation tem-perature of hydroxyapatite decreases by 134 K, and the decomposition temperature increases by 38 K. The polymorphous transformation of Ca3（PO4）2 from β phase to α phase increases by 47 K. The thermodynamic properties of the transformations at above 1073 K are also modi-fied by the addition of yttria; that is, the endothermal peaks are substituted by exothermal peaks.

关键词： bioceramics solid reaction mechanism X-ray diffraction thermal analysis yttria

Thermal-stress Simulation of Direct-chill Casting of AZ31 Magnesium Alloy Billets

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Journal of Wuhan university of Technology(materials science) 2009年第3期24卷 376-382页

作者：胡红军 college of materials science and engineering Chongqing University National engineering Research Center for Magnesium Alloys Chongqing University college of Material science and engineering Chongqing University of Technology

Two-dimensional （2D） transient coupled finite element model was developed to compute the temperature and stress field in cast billets, so as to predict the defects of the I-type billets made from AZ31 magnesium alloy and find the causes and solutions for surface cracks and shrinkages during direct-chill （DC） casting process. Method of equivalent specific heat was used in the heat conduction equation. The boundary and initial conditions used for primary and secondary cooling were elucidated on the basis of the heat transfer during the solidification of the billet. The temperature and the thermal-stress fields were simulated with the thermal-structural coupled module of ANSYS software. The influences of casting parameters on the distributions of temperature and stress were studied, which helped optimize the parameters （at pouring temperature of 680 ℃, casting speed of 2 min/s, heat-transfer coefficient of the second cooling equals to 5 000 W/m^2.℃^-1）. The simulation results of thermal stress and strain fields reveal the formation mechanism of some casting defects, which is favourable for optimizing the casting parameters and obtain high quality billets. Some measures of controlling processes were taken to prevent the defects for direct-chill casting billets.

关键词： magnesium alloy direct-chill casting temperature and stress fields numerical simulation solidification model

Photocatalytic Activities of Amorphous TiO_2-Cr Thin Films Prepared by Magnetron Sputtering

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Journal of Wuhan university of Technology(materials science) 2008年第5期23卷 610-616页

作者：黄佳木 college of materials science and engineering Chongqing University

Chrome-doped titanium oxide films were prepared by reactive magnetron sputtering method. The films deposited on glass slides at room temperature were investigated by atom force microscope, X-ray diffractometer, X-ray photoelectron spectroscopy, UV-Vis spectrophotometer, the photoluminescence （PL） and ellipse polarization apparatus. The results indicate that TiO2-Cr film exists in the form of amorphous. The prepared films possess a band gap of less than 3.20 eV, and a new absorption peak. The films, irradiated for 5 h under UV light, exhibit excellent photocatalytic activities with the optimum decomposition rate at 98.5% for methylene blue. Consequently, the thickness threshold on these films is 114 nm, at which the rate of photodegradation is 95% in 5 h. When the thickness is over 114 nm, the rate of photodegradation becomes stable. This result is completely different from that of crystalloid TiO2 thin film.

关键词： amorphous TiO2 magnetron sputtering TiO2-Cr thin films photocatalysis threshold

Phase Evolution during Carbothermic Reduction Process of Ilmenite for TiC_xN_(1-x) Composite Powders

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稀有金属材料与工程 2011年第S3期40卷 281-285页

作者： Tang Aitao1,2, Chen Min1, Wang Jian1,2, Liu Chuanpu1, Pan Fusheng1,2, Wang Weiqing1 1 college of materials science and engineering, chongqing university,chongqing 400045, china 2 National engineering Research Center for Magnesium Alloys, chongqing university, chongqing 400044, china chongqing Univ Coll Mat Sci & Engn Chongqing 400045 Peoples R China chongqing Univ Natl Engn Res Ctr Magnesium Alloys Chongqing 400044 Peoples R China

As cutting materials and wear-resistant materials, the composites reinforced by Ti(C,N) have very high performances. The super-high cost of these composites, however, limits apparently their wider application to industry due to use of very expensive Ti(C,N) powders. Therefore, it is very necessary to develop a new process technology with low fabrication cost. In the present work, ilmenite (FeTiO3), which is very cheap and very rich in china, was used to fabricate the Ti(C,N) powder directly. The phase evolution during carbothermic reduction process of ilmenite was investigated by XRD, TG-DSC and thermodynamic calculation. The ilmenite and graphite were mixed by high energy ball milling and then sintered in pure flowing nitrogen atmosphere. The experimental results showed that a new phase, Ti4O7, appeared at 900 ℃ and disappeared at 1100 ℃ while sintered in pure flowing nitrogen atmosphere. The phase evolution during carbothermic reduction process of ilmenite was found to be continuous as FeTiO3→Ti4O7→T3O5→TiCN. XRD results showed that the composite powders produced in the present reaction were composed of α-Fe and TiC1-xNx. The thermodynamic calculation results were agreeable with experimental results.

关键词： ilmenite TiCxN1-x composite powders thermodynamic calculation carbothermic reduction

Effect of Ca addition on the as-cast microstructure and creep properties of Mg-5Zn-5Sn magnesium alloy

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Rare Metals 2009年第6期28卷 576-581页

作者： YANG Mingbo CHENG Liang SHEN Jia PAN Fusheng materials science and engineering college Chongqing University of Technology Chongqing 400050 China materials science and engineering college Chongqing University Chongqing 400030 China

The effect of Ca addition on the as-cast micmstructure and creep properties of Mg-5Zn-5Sn magnesium alloy was investigated. The results indicate that adding 1.0 wt.% Ca to Mg-5Zn-5Sn alloy can effectively refine the as-cast microstructure of the alloy, and the CaMgSn phase with high thermal stability is formed in the alloy. In addition, adding 1.0 wt.% Ca to Mg-5Zn-5Sn alloy can also improve the creep properties of the alloy. After adding 1.0 wt.% Ca to Mg-5Zn-5Sn alloy, the second creep rate of the alloy at 150℃ and 50 MPa for 100 h decreases from 4.67 ×10^-8 to 1.43 × 10^-8 s^-1. The strengthening mechanism is mainly attributed to the microstructural refinement and the formation of CaMgSn phase.

关键词： magnesium alloys Ca addition creep properties microstructure