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Impact of acoustic wave propagation characteristics on aerodynamic damping of rotor blades in a transonic axial compressor

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Chinese Journal of Aeronautics 2024年第11期37卷 168-187页

作者： Yongbo YU Yanrong WANG le han School of Energy and Power Engineering Beihang UniversityBeijing 100191China Collaborative Innovation Center for Advanced Aero-Engine Beijing 100191China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

The aeroelastic stability associated with the acoustic wave propagation characteristics of transonic rotor blades was numerically investigated in this *** influence of the vibration frequency on the aerodynamic damping of the first bending mode was primarily considered at different speeds,including both work and stall *** found that the state of acoustic wave propagation associated with aeroelastic instability is closely related to rotational *** low speeds near stall points,the risk of aeroelastic instability is confined to the upstream cut-off ***,at high speeds near stall points,aeroelastic instability may occur in both the downstream cut-off state and the acoustic wave propagation state of the upstream cut-off frequency,further expanding the range of the acoustic wave propagation state in which aeroelastic instability can *** research findings show that for suction surfaces,aerodynamic work is affected not only by acoustic wave propagation characteristics,but also by shock waves,radial flow,and reflux in the flow ***,for pressure surfaces,the acoustic wave propagation characteristics play a significant *** aeroelastic instability occurs,negative damping predominantly arises from the pressure *** investigate why lower-order modes are more prone to aeroelastic instability,specific simulations were conducted for the first bending and twisting modes under different operating conditions in the downstream cut-on *** the vibration frequency significantly exceeds the downstream cutoff frequency,the blade phase is minimally influenced by acoustic wave propagation characteristics,and the rotor is aeroelastically stable in these ***,there is an approximately linear increase in the unsteady pressure amplitude with increasing vibration frequency,and the aerodynamic work is predominantly influenced by the unsteady pressure amplitude.

关键词： Aeroelastic stability Nodal diameter Aerodynamic damping Acoustic wave propagation characteristic Vibration frequency

A discussion of fatigue properties of notched specimens subjected to prestressing treatment machined from FGH4097

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Chinese Journal of Aeronautics 2024年第4期37卷 508-523页

作者： Rongxi SHI Dasheng WEI le han Shun YANG School of Energy and Power Engineering Beihang UniversityBeijing 100191China Jiangxi Research Institute Beihang UniversityNanchang 330096China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

Experimental and numerical investigations were performed to reveal the effect of prestress on the fatigue properties of FGH4097 so as to quantitatively evaluate the overspeed benefit of the disc of aeroengine. A corresponding experiment was performed to examine the effect of prestress on the fatigue life of FGH97. A complete model describing the fatigue properties of the prestressed notch specimen was proposed. After the modification of mean stress, stress gradient and prestressing treatment, the model is finally verified by fatigue test of presstressed notch specimens machined from FGH4097 with satisfactory accuracy and good engineering applicability. The new model highlights that for the variable fatigue loads, the introduction of appropriate prestress is expected to benefit to the notch specimens and certainly to the disc of aeroengine regards of their fatigue properties. Both the calculation method of fatigue life parameters and the prestress correction model are proved to have good prediction accuracy.

关键词： Turbine blisk Overspeed test Prestress Fatigue life prediction FGH4097

Lock-in phenomenon of tip clearance flow and its influence on aerodynamic damping under specified vibration on an axial transonic compressor rotor

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Chinese Journal of Aeronautics 2022年第3期35卷 185-200页

作者： le han Dasheng WEI Yanrong WANG Mingchang FANG School of Energy and Power Engineering Beihang UniversityBeijing 100083China Collaborative Innovation Center for Advanced Aero-Engine Beijing 100083China

In this study,the lock-in phenomenon of Tip Clearance Flow(TCF)instabilities and their relationship to blade vibration are investigated numerically on an axial transonic rotor with a large tip *** capabilities of simulating instability flow and lock-in phenomenon are verified on a transonic rotor and a NACA0012 airfoil by comparing with the test data,*** lock-in phenomenon is first numerically confirmed that may occur to TCF instabilities when its frequency is close to the blade vibration *** lock-in region becomes wider with the vibration amplitude increasing,and it is also affected by modal *** the rotor at the simulation conditions in this study,the bending mode results in a wider lock-in region than the torsional *** the lock-in region,the phase difference between the Tip Clearance Vortex(TCV)and the blade vibration changes with the flow condition and the frequency ratio of the blade vibration and the TCV *** frequency of the TCV instabilities reduces with the mass flow ***,reducing mass flow and increasing frequency ratio have similar effects on the TCV phase,which causes a significant variation on the unsteady pressure amplitude in the blade tip ***,the aerodynamic damping changes significantly with the TCV *** aerodynamic damping displays a nonlinear relationship with the vibration amplitude,and it changes from negative to positive with the vibration amplitude increasing at the same frequency *** negative damping is mainly provided by the tip area of the *** unlocked conditions,the period of the TCF instabilities fluctuates over time,and it cannot be directly separated by their frequency *** Blade Phase Angle(IBPA)also has an important influence on the feature of the TCV *** occurrence of frequency lock-in also requires“appropriate”*** the examined working conditions,the frequency lock-in occurs under 0 ND(Nodal Diameter),but not un

关键词： Aerodynamic damping Inter blade phase angle Lock-in Specified blade vibration Tip clearance flow instabilities

Convex Relaxation Algorithm for a Structured Simultaneous Low-Rank and Sparse Recovery Problem

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Journal of the Operations Research Society of China 2015年第3期3卷 363-379页

作者： le han Xiao-Lan Liu Department of Mathematics South China University of TechnologyGuangzhou 510641China

This paper is concerned with the structured simultaneous low-rank and sparse recovery,which can be formulated as the rank and zero-norm regularized least squares problem with a hard constraint diag(■)=*** this class of NP-hard problems,we propose a convex relaxation algorithm by applying the accelerated proximal gradient method to a convex relaxation model,which is yielded by the smoothed nuclear norm and the weighted l1-norm regularized least squares problem.A theoretical guarantee is provided by establishing the error bounds of the iterates to the true solution under mild restricted strong convexity *** the best of our knowledge,this work is the first one to characterize the error bound of the iterates of the algorithm to the true ***,numerical results are reported for some random test problems and synthetic data in subspace clustering to verify the efficiency of the proposed convex relaxation algorithm.

关键词： Simultaneous low-rank and sparse recovery Convex relaxation Error bound

Role of inositol polyphosphate-4-phosphatase type II in oncogenesis of digestive system tumors

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World Journal of Gastrointestinal Oncology 2023年第10期15卷 1706-1716页

作者： le han Shuo Chen Shi-Yu Du Peking University China-Japan Friendship School of Clinical Medicine Peking UniversityBeijing 100029China Department of Gastroenterology China-Japan Friendship HospitalBeijing 100029China

Inositol polyphosphate-4-phosphatase type II(INPP4B)is a newly discovered PI(3,4,5)P3 *** studies have revealed that INPP4B is upregulated or downregulated in tumors of the digestive system,and the abnormal expression of INPP4B may be attributed to the occurrence,development,and prognosis of tumors of the digestive *** paper reviews studies on the correlations between INPP4B and digestive system tumors and the roles of INPP4B in the development of different tumors to provide a theoretical basis for further research on its molecular mechanism and clinical application."INPP4B"and"tumor"were searched as key words in PubMed and in the CNKI series full text database retrieval system from January 2000 to August 2023.A total of 153 Englishlanguage studies and 30 Chinese-language studies were *** following enrollment criteria were applied:(1)Studies contained information on the biological structure and functions of INPP4B;(2)studies covered the influence of abnormal expression of INPP4B in digestive system tumors;and(3)studies covered the role of INPP4B in the diagnosis,treatment,and prognosis of digestive system *** excluding the literature irrelevant to this study,61 papers were finally included in the ***4B expression is low in gastric cancer,colon cancer,pancreatic cancer,and liver cancer but it has high expression in esophageal cancer,colon cancer,pancreatic cancer,and gallbladder ***4B is involved in the occurrence and development of digestive system tumors through the regulation of gene expression and signal *** abnormal expression of INPP4B plays an important role in the development of digestive system *** on INPP4B provide new molecular insights for the diagnosis,treatment,and prognosis evaluation of digestive system tumors.

关键词： Inositol polyphosphate-4-phosphatase type II Tumors of the digestive system Protein kinase B Serum and glucocorticoid-regulated kinase 3

Magnetically responsive photonic films with high tunability and stability

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Nano Research 2015年第2期8卷 611-620页

作者： Yongxing Hu le He Xiaogang han Mingsheng Wang Yadong Yin University of California Riverside Department of Chemistry California USA

We demonstrate the fabrication of magnetically assembled one-dimensional chain-like photonic nanostructures with significantly high photonic stability. The key lies in the use of agarose hydrogel to prevent coagulation of the magnetic assemblies. When exposed to an external magnetic field, negatively charged Fe3O4@SiO2 particles can effectively assemble in the hydrogel matrix into one- dimensional chains with internal periodicity and display a fast, fully reversible, and tunable photonic response to the changes in the external field. The steric hindrance and the hydrogen bonding from the agarose network effectively limit the migration of the Fe304@SiO2 particles and their chain-like assemblies. As a result, the system shows remarkable stability in photonic response under external magnetic fields of large gradients, something which has previously been a challenge. The ability to stabilize the magnetic particle assemblies over a long period represents a major stride toward practical applications of such field- responsive photonic materials.

关键词： magnetic field hydrogel reversible assembly photonic nanostructures coagulation

Synthesis and co-luminescence properties of Tb^(3+)-methacrylic acid-1,10-phenanthroline complexes doped with Eu^(3+)

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Rare Metals 2012年第5期31卷 479-483页

作者： CHEN Yan ZhanG Jing ZhanG le han Pengde WANG Lixi ZhanG Qitu College of Materials Science and Engineering Nanjing University of Technology Nanjing 210009 China

A series of rare earth complexes Tb_(1-x)Eu_x(MAA)_3phen(x=0.00, 0.01, 0.03, 0.05, 0.07, 0.09, 0.10, 0.30, and 0.50) were synthesized with MAA as the first ligand and phen as the second ligand. The complexes were characterized by means of FT-IR, thermogravimetry-differential scanning calorimetry (TG-DSC), XRD, UV absorption spectra, and photoluminescence spectra (PL). The results show that the luminescence intensity of Eu^(3+)increases as Tb^(3+) transfer the absorbed energy to Eu^(3+) in the complexes. The emission of Tb^(3+) at 545 nm is observed and increasing with x decreasing. When x=0.01, the luminescence intensity reaches the maximum value, and the emission intensity of Tb 3+ at 545 nm and Eu^(3+) at 614 nm are almost equal. It realizes the co-luminescence of Eu^(3+) and Tb^(3+) . We can obtain complexes with different colors by adjusting the ratio of Eu^(3+) to Tb^(3+) .

关键词： rare earths complexes luminescent intensity co-luminescence

Novel interface regulation of Sn1.0Ag0.5Cu composite solders reinforced with modified ZrO_(2):Microstructure and mechanical properties

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Journal of Materials Science & Technology 2022年第30期125卷 157-170页

作者： Fupeng Huo Zhi Jin Duy le han Jiahui Li Keke Zhang Hiroshi Nishikawa Joining and Welding Research Institute Osaka UniversityIbarakiOsaka 565-0047Japan Graduate School of Engineering Osaka UniversitySuitaOsaka 565-0871Japan School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471023China Department of Welding Engineering and Metals Technology School of Mechanical EngineeringHanoi University of Science and TechnologyNo.1 Dai Co VietHai Ba TrungHanoiViet Nam

With the trends of miniaturization and high density of electronic packaging,there has been an urgent demand to open up lead-free solders with high strength and *** this study,a ZrO_(2)-reinforced Sn1.0Ag0.5Cu composite solder was ***,surface modification on ZrO_(2) was conducted with ball milling-pyrolysis ***,NiO modified ZrO_(2)(NiO/ZrO_(2))was added to the solder matrix with ultrasonic *** morphology and interface of NiO/ZrO_(2) were ***,the microstructure,interface and mechanical properties of the composite solders were systematically *** results showed that NiO nanoparticles were evenly adhered to the ZrO_(2) surface,and the interface relationship between them was semi-coherent and ***,an appropriate addition of NiO/ZrO_(2) could refine the microstructure of composite *** refinement mechanism was systematically ***,a micro-mechanical lock and non-micropored clean interface was formed between NiO/ZrO_(2) and the solder *** Sn/NiO/ZrO_(2) interface system based on mutual solid solution was ingeniously *** ultimate tensile strength and elongation were increased synergistically,and the fracture mechanism transformed from a ductile−brittle mixed fracture mode to a ductile fracture ***,a lead-free solder with high strength and ductility was obtained.

关键词： SnAgCu composite solder ZrO_(2)nanoparticles Refinement mechanism Surface modification Interface Reinforcements

Two comparable Ba-MOFs with similar linkers for enhanced CO_(2)capture and separation by introducing N-rich groups

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Rare Metals 2021年第2期40卷 499-504页

作者： Ying Zhao Jiao Liu Min-le han Guo-Ping Yang Lu-Fang Ma Yao-Yu Wang College of Chemistry and Chemical Engineering Henan Key Laboratory of Function-Oriented Porous MaterialsLuoyang Normal UniversityLuoyang471934China Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education Shaanxi Key Laboratory of Physico-Inorganic ChemistryCollege of Chemistry and Materials ScienceNorthwest UniversityXi’an710127China

Two new different metal-organic frameworks(MOFs)[Ba(L1)(H_(2)O)_(2)]_(n)·nH_(2)O(MOF 1)and[Ba(L2)(-n2 O)_(2)]_(n)·0.5 nDMF·0.5 nH_(2)O(MOF 2)were yielded by the assembly of oxygen-friendly Ba(Ⅱ)ions and two similar linkers,namely 2-(imidazol-1-yl)terephthalic acid(H_(2)L1)and 2-(1 H-1,2,4-triazol-1-yl)terephthalic acid(H_(2)L2).Single-crystal X-ray diffractions(XRD)indicate that MOF1 is a new three-dimensional(3 D)stacking dense network formed by the one-dimensional(1 D)rod-shaped chains and L1 linkers,whereas MOF 2 presents a 3 D nanotube porous framework with cylindrical tunnels based on the 1 D loop chains as the secondary building units(SBUs)by replacing the imidazole group in H_(2)L1 with the triazole group in H_(2)*** a result,MOF 2 has a higher density of active sites and lewis acid sites in the porous surface of nanotube than MOF ***,the CO_(2)capture and separation capacity of MOF 2 is great higher than that of CH_(4)at298 K.

关键词： MOFs Similar linkers Secondary building units(SBUs) CO_(2)capture Isosteric heat