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μ-Synthesis control with reference model for aeropropulsion system test facility under dynamic coupling and uncertainty

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Chinese Journal of Aeronautics 2023年第10期36卷 246-261页

作者： Jiashuai liu Xi WANG Xi liu Meiyin ZHU Xitong PEI Song ZHANG Zhihong DAN School of Energy and Power Engineering Beihang UniversityBeijing 100191China Zhongfa Aviation Institute Beihang UniversityHangzhou 311115China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China Science and Technology on Altitude Simulation Laboratory AECC(Aero Engine Corporation of China)Sichuan Gas Turbine EstablishmentMianyang 621703China

Due to the dynamic coupling and multi-source uncertainties,it is difficult to accurately control the pressure and temperature of the Aeropropulsion System Test Facility(ASTF)in the presence of rapid command and large *** paper presents the design ofμ-synthesis control to solve the *** incorporating the pressure ratio into the linear equation of the control valve,the modeling error of ASTF in the low frequency range is effectively ***,an uncertain model is established by considering various factors,including parameter variations,modeling error in the low frequency range,unmodeled dynamics,and changes in the working *** address the dynamic coupling,a diagonal reference model with desired performance is incorporated intoμ-***,all weighting functions are designed according to the performance ***,theμ-controller is obtained by using the standardμ-synthesis *** results indicate that theμ-controller decouples the pressure and temperature dynamics of *** with the multivariable PI controller,integral-μcontroller,and double integral-μcontroller,the proposedμ-controller can achieve higher transient accuracy and better disturbance ***,the robustness of theμ-controller is demonstrated by Monte Carlo simulations.

关键词： Aeropropulsion System Test Facility(ASTF) Decoupling Robustness μ-Synthesis Uncertainty

Desiccant Performance Evaluation of Desiccant-Coated Heat Exchanger-Based Heat Pump by Equilibrium Model

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Journal of Thermal Science 2023年第6期32卷 2361-2373页

作者： liu Yuexin liu Zhilu XIA Xiaoxiao LI Wei TU Zhengkai CAI Shanshan LI Song School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan430074China

By combining the advantages of desiccant dehumidification and vapor compression refrigeration,the desiccant-coated heat exchanger-based heat pump(DCHE HP)is regarded as a promising alternative to the traditional vapor-compression air conditioning system(VCAC).Selecting proper desiccants from a large number of candidates is of great importance to improve the performance of DCHE ***,this task is challenging using current experimental or modelling *** this work,we developed an equilibrium model to evaluate the power consumption of 39 DCHE HPs coated with different desiccants under various operating ***,five desiccants with low power consumption were *** was also demonstrated that under given operating conditions,the DCHE HP based on the five selected desiccants can save 21.3%–32.9%power compared with the *** power consumption of the DCHE HP is largely dependent on the heat of adsorption,the cyclical water uptakes and the remained moisture contents of the coating *** was further revealed that the moderate heat of adsorption,the larger cyclical water uptake and the lower remained moisture content are preferable for reducing the system energy *** work reported a quick evaluation of 39 desiccants for DCHE HP by an equilibrium model,which may also offer insights into the choosing and designing of desiccants for DCHE HP.

关键词： adsorption metal-organic frameworks dehumidification power consumption relative humidity

Tandem catalysis on adjacent active motifs of copper grain boundary for efficient CO_(2) electroreduction toward C2 products

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Journal of Energy Chemistry 2022年第7期31卷 219-223,I0006页

作者： Tao Luo Kang liu Junwei Fu Shanyong Chen Hongmei Li Junhua Hu Min liu Hunan Joint International Research Center for Carbon Dioxide Resource Utilization State Key Laboratory of Powder MetallurgySchool of Physics and ElectronicsCentral South UniversityChangsha 410083HunanChina School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450002HenanChina

Copper (Cu) is a special electrocatalyst for CO_(2) reduction reaction (CO_(2)RR) to multi-carbon *** introducing grain boundaries (GBs) into Cu-based catalysts is an efficient strategy to improve the selectivity of C^(2+) ***,it is still elusive for the C^(2+) product generation on Cu GBs due to the complex active *** this work,we found that the tandem catalysis pathway on adjacent active motifs of Cu GB is responsible for the enhanced activity for C^(2+)production by first principles *** electronic structure analysis shows,the d-band center of GB site is close to the Fermi level than Cu(100) facet,the Cu atomic sites at grain boundary have shorter bond length and stronger bonding with*CO,which can enhance the adsorption of*CO at GB ***,CO_(2)protonation is more favorable on the region Ⅲ motif (0.84 e V) than at Cu(100) site (1.35 e V).Meanwhile,the region Ⅱ motif also facilitate the C–C coupling (0.72 e V) compared to the Cu(100) motif (1.09 e V).Therefore,the region Ⅲ and Ⅱ motifs form a tandem catalysis pathway,which promotes the C^(2+)selectivity on Cu *** work provides new insights into CO_(2)RR process.

关键词： Cu(100)facet Grain boundary CO_(2)electroreduction C2+products Tandem catalysis

N-doped CNTs capped with carbon layer armored CoFe alloy as highly stable bifunctional catalyst for oxygen electrocatalysis

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Nano Research 2022年第5期15卷 3971-3979页

作者： Bin Wang Katam Srinivas Yanfang liu Dawei liu Xiaojuan Zhang Wanli Zhang Yuanfu Chen State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China College of Science and Institute of Oxygen SupplyTibet UniversityLhasa 850000China

Designing and fabricating the bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)has long posed an uphill and pressing task for the interconversion of electricity and *** this in mind,herein,we propose a novel hierarchical nanoarchitecture of N-doped carbon nanotubes capped with carbon layer armored CoFe alloy(CoFe@NC-NT),which is facilely fabricated by spray drying and subsequent annealing *** a bifunctional electrocatalyst,the well-designed CoFe@NC-NT shows a remarkably low overpotential of 257 mV and a half-wave potential of 0.74 V to obtain 10 mA·cm^(-2)in OER and ORR,***,it is also characterized by exceptional operating stability to meet practical application for Zn-air *** high catalytic activity of CoFe@NC-NT is attributed to the tight contact between the highly conductive nanotubes and metal alloy *** the qualified stability is ascribed to the coating effect of carbon layer shell to alloy *** the unique structural evolution with enhanced oxygen-involved reaction activity,we believe that this work can provide an appealing innovative approach towards the directed self-assembly of functional nanostructures to realize satisfying overall performance.

关键词： oxygen electrocatalysis metal alloy coating effect self-assembly Zn-air battery

Dynamics of the spatiotemporal velocity of glaciers on the eastern slope of Mount Gongga,China,under climate change

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Advances in Climate Change Research 2024年第3期15卷 490-499页

作者： Yin FU Bo ZHANG Qiao liu Guo-Xiang liu Rui ZHANG Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610299China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China

The quantitative assessment of glacier flow velocity dynamics plays a pivotal role in understanding its response mechanisms concerning climate *** work provides a systematic quantitative assessment of the deceleration status of glaciers in this region by investigating the motion evolution of typical glaciers in Mount Gongga in recent years,thereby revealing the seasonal dynamics and inter-annual evolution over an extensive time *** used the optical flow-small baseline subset(OF-SBAS)method to compute the time-series velocities of the Hai-luogou Glacier and the Mozigou Glacier using 178 archived Sentinel-1 satellite synthetic aperture radar(SAR)images from 2014 to *** findings revealed a prominent seasonal pattern in glacier motion,characterised by cyclic variations in velocity from cold to warm ***,we identified variations in velocities across distinct regions of the glacier surface,underscored by the lag in the peak time node of glacier flow with increasing *** pattern may have been determined by a combination of internal and external factors,including mass accumulation and ablation-driven subglacial drainage,as well as the glacier geomorphological ***,during 2015-2021,the glaciers on the eastern slope of Mount Gongga exhibited an overarching trend of ***,the ablation area of the Hailuogou Glacier recorded the most substantial deceleration,exceeding 8%per *** study underscores the efficacy of the OF-SBAS method in extracting long-term glacier *** work also establishes a robust foundation for the analysis of spatiotemporal fluctuations in glacier movement within the context of climate warming.

关键词： Monsoonal temperate glaciers Synthetic aperture radar(SAR) Glacier movement Hailuogou glacier Mozigou glacier Optical flow-small baseline subset(OF-SBAS)

Rapid identification of chemical profile in Gandou decoction by UPLCQ-TOF-MSE coupled with novel informatics UNIFI platform

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Journal of Pharmaceutical Analysis 2020年第1期10卷 35-48页

作者： Li Xu Yi liu Hongfei Wu Huan Wu Xiaochuang liu An Zhou The Experimental Research Center Anhui University of Chinese MedicineHefei 230038China Anhui Province Key Laboratory of Chinese Medicinal Formula Hefei 230012China Waters Corporation(China) Shanghai 201206China

Gandou decoction(GDD),a well-known traditional Chinese medicine(TCM)formula,has been widely used for decades to treat Wilson's disease(WD)in China due to its remarkable clinical ***,the chemical constituents of GDD still remain unclear because of their *** this work,a reliable and sensitive strategy based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry(UPLC-Q-TOF-MSE)and UNIFI informatics platform was applied to investigate the chemical components in *** total,96 compounds including anthraquinones,alkaloids,protostane triterpenoids,flavonoids,triterpenoid saponins,tannins,curcuminoids,etc,were identified or tentatively characterized from GDD by comparing their retention time,accurate mass within 5 ppm error and MSE fragmentation *** them,eleven compounds were confirmed unambiguously with reference *** compounds in different chemical structure types were analyzed in fragmentation patterns and characteristic ***,to better understand the chemical contribution of individual herbs to the whole decoction,the corresponding each herb in GDD was also *** study developed a rapid method for characterizing the chemical constituents in GDD,which could not only be used for chemical standardization and quality control,but also be helpful for further research of GDD in vivo.

关键词： Gandou decoction UPLC-Q-TOF-MSE UNIFI informatics platform Chemical constituents

Numerical simulation on the evolution of cloud particles in 3-D convective cloud

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Science China Earth Sciences 2009年第8期52卷 1195-1206页

作者： XiaoLi liu ShengJie Niu Key Laboratory of Meteorological Disaster of Ministry of Education School of Atmospheric Physics Nanjing University of Information Science & Technology Nanjing 210044 China

A 3-D convective cloud model with compressible non-hydrostatic dynamics and the spectral bin microphysics of a 2-D slab-symmetric model has been used to simulate an observed supercell storm occurring on 29 June, 2000 ... 详细信息

关键词： spectral bin microphysics 3-D convective cloud numerical simulation evolution of particle spectrum

Structure evolution,dielectric,and conductivity behavior of(K_(0.5)Na_(0.5))NbO_(3)-Bi(Zn_(2/3)Nb_(1/3))O_(3) ceramics

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Journal of Advanced Ceramics 2021年第4期10卷 809-819页

作者： Tianxiang YAN Kaiyuan CHEN Chengqi LI Min liu Jie WANG Liang FANG Laijun liu College of Mechanical and Control Engineering&College of Materials Science and Engineering Guilin University of TechnologyGuilin 541004China Institute of Fluid Engineering Equipment Jiangsu Industrial Technology Research InstituteJiangsu UniversityZhenjiang 212013China Key Laboratory for RF Circuits and Systems Ministry of Education&Key Laboratory of Large Scale Integrated DesignHangzhou Dianzi UniversityHangzhou 310018China

(1-x)K_(0.5)Na_(0.5)Nb0_(3-x)Bi(Zn_(2/3)Nb_(1/3))0_(3)((1-x)KNN-xBZN,x=0.010,0.015,0.020,0.025,and 0.030)lead-free ceramics were fabricated via a traditional solid-state *** crystal structure,microstructure,dielectric,and conductivity behavior of this system were *** with X-ray diffraction(XRD)patterns,Rietveld refinement,and dielectric spectroscopy,an orthorhombic phase was determined for x=0.010,an orthorhombic-tetragonal mixed phase was identified for x=0.015,and a rhombohedral symmetry appears in 0.020≤x≤*** 0.98KNN-0.02BZN and 0.975KNN-0.025BZN ceramics exhibit stable permittivity and low dielectric loss tangent(tan)in wide temperature ranges owing to the combination of rhombohedral-tetragonal step-like feature and the diffuse phase transition from tetragonal to *** activation energies of dielectric relaxation and conductivity behavior at high temperatures initially decrease slightly,then drop sharply,and finally decline slowly,which could be attributed to microstructure morphologies and the concentration of oxygen vacancies.

关键词： ceramic crystal structure dielectric spectroscopy oxygen vacancies

On the number of P-invariant closed characteristics on partially symmetric compact convex hypersurfaces in R^(2n)

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Science China Mathematics 2015年第8期58卷 1771-1778页

作者： liu Hui ZHANG DuanZhi School of Mathematical Sciences University of Science and Technology of China School of Mathematical Sciences and LPMC Nankai University

In this paper, let n ≥ 2 be an integer, P = diag（-In-k,In-k,Ik） for some integer κ∈[0, n）, and ∑∪→R^2n be a partially symmetric compact convex hypersurface, i.e., x ∈∑ implies Px∈∑. We prove that if ∑ is （r, R）-pinched with R/r〈 √2, then there exist at least n -k geometrically distinct P-symmetric closed ∑ characteristics on ∑, as a consequence, Z carry at least n geometrically distinct P-invariant closed characteristics.

关键词： compact convex hypersurfaces P-symmetric closed characteristics Hamiltonian system