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Large magnetic refrigerant capacity of HoFe_(1-x)Co_(x)Al(x=0,0.3)compounds

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Rare Metals 2021年第10期40卷 2868-2872页

作者： Zhi-Yi Xu Zhi-gao Zhang Rong-Li gao Wen-Jie Gong Rui-fen Hou An-Li Lin National Institute of Metrology(NIM) Beijing 100029China School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing 401331China

Magnetic and magnetocaloric properties of HoFe_(1-x)Co_(x)Al(x = 0, 0.3) were investigated. Both HoFeAl and HoFe_(0.7)Co_(0.3) Al undergo a second-order ferromagnetic(FIM) to paramagnetic(PM) transition at Curie temperatures(TC) of 87 and 82 K, respectively. The magnetocaloric effect is improved by the introduction of Co in HoFeAl compound. For a field change from 0 to 5 T,the maximum values of magnetic entropy change(﹣△SM)are 7.0 J·kg^(-1)·K^(-1) for HoFeAl and 8.6 J·kg^(-1)·K^(-1) for HoFe_(0.7)Co_(0.3) Al. In addition, the refrigerant capacity(RC)is enhanced largely from 416.2 J·kg^(-1) for HoFeAl to561.9 J·kg^(-1) for HoFe_(0.7)Co_(0.3) Al. This large RC is attributed to the large ﹣?SM and the wide temperature span of ?SM peak in HoFe_(0.7)Co_(0.3) Al compound. The physical mechanism of improvement in magnetocaloric effect by Co substitution in HoFeAl was also discussed in detail.

关键词： RTX compound Intermetallic compound Magnetocaloric effect Refrigerant capacity

Identification of LPV system using locally weighted technique

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Applied Mathematics(A Journal of Chinese Universities) 2010年第4期25卷 411-419页

作者： ZENG Jiu-sun gao chuan-hou LUO Shi-hua Department of Mathematics Zhejiang University Hangzhou 310027 China School of Management Jiangxi University of Finance and Economics Nanchang 331300 China

The problem of linear parameter varying （LPV） system identification is considered based on the locally weighted technique which provides estimation of the LPV model parameters at each distinct data time point by giving large weights to measurements that are ＂close＂ to the current time point and small weights to measurements ＂far＂ from the current time point. Issues such as choice of distance function, weighting function and bandwidth selection are discussed. The developed method is easy to implement and simulation results illustrate its efficiency.

关键词： Linear parameter varying system locally weighted technique identification.

Quantifying Discriminating Strength for Gaussian States

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Communications in Theoretical Physics 2018年第8期69卷 127-131页

作者： Rui-fen Ma Xiao-Fei Qi Jin-chuan Hou Department of Mathematics Shanxi UniversityTaiyuan 030006China Department of Mathematics Taiyuan University of Science and TechnologyTaiyuan 030024China Institute of Big Data Science and Industry Shanxi UniversityTaiyuan 030006China Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China

The discriminating strength DS(ρAB) induced by local Gaussian unitary operators for any(n + m)-mode Gaussian state ρABis introduced in [Phys. Rev. A 83(2011) 042325]. In this paper, we further discuss the quantity by restricting to Hilbert-Schmidt norm. The analytic formulas of DS for two-mode squeezed thermal states and mixed thermal states are given. Then, the relationship between DS(ρAB) and DS((I ? Φ)(ρAB)) for some special Gaussian channels Φ is discussed. In addition, DS is compared with Gaussian entanglement for symmetric squeezed thermal states.

关键词： Gaussian states discriminating strength Gaussian unitary operators quantum correlations

Idealized Experiments for Optimizing Model Parameters Using a 4D-Variational Method in an Intermediate Coupled Model of ENSO

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Advances in Atmospheric Sciences 2018年第4期35卷 410-422页

作者： chuan gao Rong-Hua ZHANG Xinrong WU Jichang SUN Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China Institute of Oceanographic Instrumentation Shandong Academy of Sciences Qingdao 266001 China University of Chinese Academy of Sciences Beijing 100029 China Key Laboratory of Marine Environmental Information Technology State Oceanic Administration National Marine Data and Information Service Tianjin 300000 China

Large biases exist in real-time ENSO prediction, which can be attributed to uncertainties in initial conditions and model parameters. Previously, a 4D variational （4D-Vat） data assimilation system was developed for an intermediate coupled model （ICM） and used to improve ENSO modeling through optimized initial conditions. In this paper, this system is further applied to optimize model parameters. In the ICM used, one important process for ENSO is related to the anomalous temperature of subsurface water entrained into the mixed layer （Te）, which is empirically and explicitly related to sea level （SL） variation. The strength of the thermocline effect on SST （referred to simply as ＂the thermocline effect＂） is represented by an introduced parameter, （l＇Te. A numerical procedure is developed to optimize this model parameter through the 4D-Var assimilation of SST data in a twin experiment context with an idealized setting. Experiments having their initial condition optimized only, and having their initial condition plus this additional model parameter optimized, are compared. It is shown that ENSO evolution can be more effectively recovered by including the additional optimization of this parameter in ENSO modeling. The demonstrated feasibility of optimizing model parameters and initial conditions together through the 4D-Var method provides a modeling platform for ENSO studies. Further applications of the 4D-Vat data assimilation system implemented in the ICM are also discussed.

关键词： intermediate coupled model ENSO modeling 4D-Var data assimilation system optimization of model param- eter and initial condition

Growth Kinetics of Laves Phase and Its Effect on Creep Rupture Behavior in 9Cr Heat Resistant Steel

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Journal of Iron and Steel Research International 2016年第7期23卷 685-691页

作者： Zhi-xin XIA chuan-yang WANG Chen LEI Yun-ting LAI Yan-fen ZHAO Lu ZHANG Shagang School of Iron and Steel Soochow University Suzhou 215021 Jiangsu China School of Mechanical and Electric Engineering Soochow University Suzhou 215021 Jiangsu China Laser and Optoelectronics Technologies Institute of Ningho China Academy of Engineering Physics Ningbo 315100 Zhejiang China Suzhou Nuclear Power Research Institute Suzhou 215004 Jiangsu China

The effects of Laves phase formation and growth on creep rupture behaviors of P92 steel at 883 K were *** microstructural evolution was characterized using scanning electron microscopy and transmission electron *** modeling was carried out using the software *** results indicated Fe_2（W,Mo）Laves phase has formed during creep with 200 MPa applied stress at 883 Kfor 243 *** experimental results showed a good agreement with thermodynamic *** plastic deformation of laths is the main reason of creep rupture under the applied stress beyond 160 MPa,whereas,creep voids initiated by coarser Laves phase play an effective role in creep rupture under the applied stress lower than 160 *** phase particles with the mean size of 243 nm lead to the change of creep rupture *** at the vicinity of fracture surface,the gage portion and the threaded ends of creep rupture specimens were also observed,indicating that creep tensile stress enhances the coarsening of Laves phase.

关键词： heat resistant steel Laves phase microstructure plastic deformation creep rupture

The 2020–2021 prolonged La Niña evolution in the tropical Pacific

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Science China Earth Sciences 2022年第12期65卷 2248-2266页

作者： chuan gao Maonan CHEN Lu ZHOU Licheng fenG Rong-Hua ZHANG Key Laboratory of Ocean Circulation and Waves Institute of OceanologyCenter for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China Laoshan Laboratory Qingdao 266237China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100029China Center for Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China National Marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China

The evolution of sea surface temperature(SST)in the tropical Pacific during 2020–2021 indicates a second-year cooling in late 2021 again,following the 2020 La Niña *** physical explanations are still lacking,and there is a clear need to understand the underlying processes *** data and reanalysis products are used to describe the characteristics and spatiotemporal evolution of upper-ocean thermal anomalies;an intermediate coupled model(ICM)is also used to perform numerical experiments to confirm these observation-based *** evolution of subsurface thermal anomalies is critically important to that of SST in the central-eastern equatorial Pacific;the effects of the former on the latter can be well represented by the temperature of subsurface waters entrained into the mixed layer(Te),a field that reflects a subsurface forcing on *** SST evolution is sensitively dependent on the intensities of the local effect associated with Te anomalies in the eastern equatorial Pacific and the remote effect associated with subsurface anomalies from the western *** early-and mid-2021,a competition was present between these local and remote effects associated with Te *** the remote warming effect dominates the local cooling effect,the cold SST condition in the east is likely to turn into neutral and warm conditions;otherwise,it tends to *** addition,the negative Te anomalies were sustained and enhanced by off-equatorial processes due to equatorial wave reflections at the eastern boundary associated with the 2020 La Niña *** SST evolution in mid-2021 corresponded to a situation in which the warming effect associated with positive subsurface thermal anomalies from the west were not strong enough to counteract the local cooling effect associated with negative anomalies in the *** due course,cold SST anomalies in the east developed again and the second-year cooling reoccurred in late 2021,with a turning point in

关键词： Prolonged La Niña evolution in 2020-2021 Subsurface effect on SST Remote and local processes Modeling experiments

Bi-salt electrolyte for aqueous rechargeable aluminum battery

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Journal of Energy Chemistry 2022年第4期31卷 613-620页

作者： Yaning gao Yu Li Haoyi Yang Lumin Zheng Ying Bai chuan Wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing 314019ZhejiangChina

The exertion of superior high-energy density based on multivalent ions transfer of rechargeable aluminum batteries is greatly hindered by limited electrochemical stability window of typical water in salt electrolyte(Wi SE). Recently, it is reported that a second salt addition to the Wi SE can offer further suppression of water activities, and achieves a much wider electrochemical window compared with aqueous Wi SE electrolytes. Hence, we demonstrate a class of water in bi-salt electrolyte containing the trifluoromethanesulfonate(OTF), which exhibits an ultra-wide electrochemical window of 4.35 V and a very low overpotential of 14.6 m V. Moreover, the interface chemistry between cathode and electrolyte is also confirmed via kinetic analysis. Surprisingly, we find the electrolyte can effectively suppress Mn dissolution from the cathode, alleviate self-discharge behavior, and ensure a stable electrode–electrolyte interface based on the interface concentrated-confinement effect. Owing to these unique merits of water in bi-salt electrolyte, the AlxMnO_(2)·nH_(2)O material delivers a high capacity of 364 m Ah g;and superb long-term cycling performance > 150 cycles with a capacity decay rate of 0.37% per cycle with coulombic efficiency at ca. 95%.

关键词： Rechargeable aluminum battery Water in bi-salt electrolyte Wide electrochemical window Stable surface Reaction mechanisms

Co-YPO_(4)双功能催化剂促进乙醇高值转化制丁二烯

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Chinese Journal of Catalysis 2024年第1期56卷 166-175页

作者：周百川李文翠王嘉孙丹卉向诗煜高新芊陆安慧大连理工大学化工学院辽宁省低碳资源高值化利用重点实验室精细化工国家重点实验室辽宁大连116024

丁二烯是重要的化工原料,主要用于生产树脂、合成橡胶、丁二醇和己二腈等大宗化学品,还可以用于制备蒽醌、四氢苯酐等精细化学品.目前,工业上制备丁二烯的方法主要是乙烯副产抽提法.近年来,随着生物乙醇技术大力发展,催化乙醇制丁二烯... 详细信息

丁二烯是重要的化工原料,主要用于生产树脂、合成橡胶、丁二醇和己二腈等大宗化学品,还可以用于制备蒽醌、四氢苯酐等精细化学品.目前,工业上制备丁二烯的方法主要是乙烯副产抽提法.近年来,随着生物乙醇技术大力发展,催化乙醇制丁二烯成为很有吸引力的生产丁二烯的路线之一.目前催化乙醇制丁二烯的催化剂种类较多,合理设计具有活性位点结构和功能的催化新材料是提升催化剂活性的关键.稀土金属元素如Y,La和Ce等具有独特的电子层结构,并且具有中等强度的Lewis酸性,本文尝试将稀土磷酸盐与具有乙醇脱氢活性的过渡金属位点结合起来,设计过渡金属改性的稀土磷酸盐催化剂并用于乙醇转化制丁二烯.本文开发了Co-YPO_(4)双功能催化剂,应用于乙醇转化制丁二烯反应,所制材料表现出较高的催化活性与稳定性.在YPO4催化剂上,乙醇主要发生脱水反应,生成大量的乙烯和乙醚,且丁二烯选择性不超过5%;而在Co-YPO_(4)催化剂上,乙醇转化产物分布出现明显改变,丁二烯选择性增加.在乙醇重时空速和反应温度分别为1.0 gC2H5OH×gCat.‒1×h^(‒1)和350℃的条件下,乙醇转化率为78.2%,丁二烯选择性为68.5%.原位紫外-可见漫反射光谱、X射线光电子能谱以及H_(2)^(-)程序升温还原表征结果表明,Co2+中心与PO_(4)^(3‒)基团存在强的配位相互作用,形成稳定且高度分散的[Co-O-P]物种.通过NH_(3)^(-)程序升温脱附(TPD)和吡啶探针分子吸附红外对YPO4和Co-YPO4进行酸性表征,结果表明,YPO_(4)和Co-YPO4表面均是典型的Lewis酸性位点;结合CO_(2)-TPD表征发现,Co^(2+)与YPO4表面部分Y3+位点发生置换,即引入适量的Co会减弱酸性同时增强表面碱性.进一步通过停留时间、乙醇程序升温表面反应和原位乙醇吸附反应漫反射红外光谱测试对反应机理进行详细研究.结果表明,乙醇首先在Co^(2+)位发生脱氢生成乙醛和H_(2),随后乙醛迁移至Y^(3+)位点吸附活化,两分子乙醛依次发生C‒C偶联、加氢以及脱水反应生成丁二烯.动力学测试结果表明,乙醇脱氢是整个反应过程的关键步骤,整体反应路径如下:乙醇→乙醛→丁烯醛→丁烯醇→丁二烯.综上所述,以乙醇作为平台分子合成丁二烯能够丰富可持续发展的新能源结构体系.本文揭示了磷酸根基团通过配位作用稳定Co^(2+)物种,Co^(2+)和Y^(3+)位点协同催化乙醇选择性生成丁二烯,为乙醇高值转化催化剂设计提供了新思路.

关键词：乙醇丁二烯脱氢碳碳偶联磷酸盐

Molecular modulating of cobalt phthalocyanines on aminofunctionalized carbon nanotubes for enhanced electrocatalytic CO_(2)conversion

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Nano Research 2023年第3期16卷 3649-3657页

作者： Huajian Xu Huizhu Cai Linxia Cui Limei Yu Rui gao chuan Shi State Key Laboratory of Fine Chemicals College of Chemical EngineeringDalian University of TechnologyDalian 116024China College of Chemistry and Chemical Engineering Inner Mongolia UniversityHohhot 010021China

Metal porphyrins and metal phthalocyanines(Pc)constitute a promising class of metal molecular catalysts(MMCs)for efficient CO_(2)-to-CO electrocatalytic conversion due to their well-defined molecular *** to adjust the local coordination and electronic environment of the metal center and enhance the molecular-level dispersion of the active components remains as great challenges for further improving the ***,a cobalt(II)Pc(CoPc)-COOH/carbon nanotube(CNT)-NH_(2)hybrid catalyst was rationally designed by clicking the CoPc-COOH molecules onto the surface of CNT-NH_(2)through amidation *** novel hybrid catalyst exhibited the enhanced current density of 22.4 mA/cm2 and CO selectivity of 91%at−0.88 V *** hydrogen electrode(RHE)in the CO_(2)electroreduction,as compared with CoPc-COOH/CNT and CoPc/CNT *** superior activity was ascribed to the charge transfer induced by introduction of-COOH and-NH_(2)functional groups to CoPc and CNT,respectively,facilitating the active centers of CoI being generated at lower potentials,and leading to the highest turnover frequency(TOF)being obtained over the CoPc-COOH/CNT-NH_(2)hybrid *** inherent directivity and saturability of covalent bonds formed via the amidation reaction ensure not only a higher density of Co active centers,but also an improved stability for CO_(2)reduction reaction(CO_(2)RR).The present study represents an effective strategy for improving MMCs performance by molecular modulating of metal phthalocyanines on functionalized carbon substrates directed by click confinement chemistry.

关键词： electrocatalytic CO_(2)reduction cobalt tetracarboxylphthalocyanine amino functionalized carbon nanotubes amidation