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A neural network solution of first-passage problems

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Applied Mathematics and Mechanics(English Edition) 2024年第11期45卷 2023-2036页

作者： Jiamin qIAN Lincong chen J.q.SUN College of Civil Engineering Huaqiao UniversityXiamen361021Fujian ProvinceChina Department of Mechanical Engineering University of CaliforniaMercedCA95343USA

This paper proposes a novel method for solving the first-passage time probability problem of nonlinear stochastic dynamic *** safe domain boundary is exactly imposed into the radial basis function neural network(RBF-NN)architecture such that the solution is an admissible function of the boundary-value *** this way,the neural network solution can automatically satisfy the safe domain boundaries and no longer requires adding the corresponding loss terms,thus efficiently handling structure failure problems defined by various safe domain *** effectiveness of the proposed method is demonstrated through three nonlinear stochastic examples defined by different safe domains,and the results are validated against the extensive Monte Carlo simulations(MCSs).

关键词： first-passage time probability nonlinear stochastic dynamic system radial basis function neural network(RBF-NN) safe domain boundary Monte Carlo simulation(MCS)

Tuning the morphologies of SiC nanowires via the change of the Co_xSi_y melts

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Nano-Micro Letters 2010年第1期2卷 11-17页

作者： J.J.chen Y.Pan w.H.Tang q.Shi Department of Physics Center for Optoelectronics Materials and Devices Zhejiang Sci-Tech University Department of Materials Science and Engineering Zhejiang University Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University) Ministry of education

SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tuned by altering the composition of CoxSiy. Nanowires obtained by thermal evaporation of Co Si are composed of SiC/SiO2 core-shell nanostructures with lengths up to several hundreds of micrometers, diameters of 4050 nm, and the thickness of amorphous SiO2 wrapping shell about 20 nm. SiC nanowires prepared by thermal evaporation of Co Si2 and Co2 Si melt are found to be hexagonal-prism-shaped nanorods, and the diameter of those nanorods is about 150 nm and the length is about 10 microns. All the SiC nanowires obtained possess [111] preferred growth direction with a high density stacking faults and twin defects. Taking into consideration the binary alloy diagram of Co Si and the participation of oxygen, we propose the vapor-solid growth mechanism of SiC nanowires and discuss the effect of the supersaturation of Si O on the morphology and yields of SiC nanowires.

关键词： Silicon carbide Nanowires Morphology

COMPARISON OF MATERIAL FOR ENCAPSULATING MINIMODULES

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 380-384页

作者： Z.Zhang H.Shen X.q.Xu w.chen GuangzhouInstituteofEnergyConversion TheChineseAcademyofSciencesGuangzhou510070China GuangzhouInstituteofEnergyConversion TheChineseAcademyofSciencesGuangzhou510070China／／TheSchoolofPhysicsandEngineeringZhongshanUniversityGuangzhou510640China

The main characteristics of glass, polymethyl methacrylate (PMMA) and polycarbon ate (PC) were presented. The transmittance of glass, PMMA and PC was measured by the UV-VIS spectroscopy analysis. PMMA and PC have the advantages of higher tra nsparency, higher resistance and lower density. It is indicated that both PMMA a nd PC are suitable for encapsulating solar minimodules.

关键词： solar module PMMA PC encapsulate

NUMERICAL SIMULATION OF EXTRUSION OF COMPOSITE POwDERS PREPARED BY HIGH ENERGY MILLING

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 51-54页

作者： X.q.Li w.P.chen w.Xia q.L.Zhu Y.Y.Li E.D.wang College of Mechanical Engineering South China University of Technology.Guangzhou 510640 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/Al composite powders prepared by high energy milling was simulated. It was from the numerical analysis that the predicted extrusion pressure mounted up with milling time and extrusion ratio increasing, which was perfect agreement with experimental results.

关键词： high energy milling composite powder plastic constitutive equation extrusion numerical simulation

Experimental study of corner separation and unsteady characteristics in linear compressor cascades with and without sweeping jet actuator

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Propulsion and Power Research 2024年第3期13卷 360-374页

作者： S.w.chen w.H.Li C.Xu q.H.Meng School of Energy Science and Engineering Harbin Institute of TechnologyHarbinHeilongjiang 150001China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

Sweeping jet actuator(SJA)has been widely applied for activeflow control in *** this paper,the SJA character in compressor cascade and its performance for separation control in innerflows are ***-averaged and transientflowfield measurement,together with visualization methods are *** is found that endwall effects are important for both SJA behaviors and SJA performance for separation control in compressor *** is a maximum of 12.7%total pressure loss reduction with SJA placed near the separation position,close to the endwall and under *** characteristic frequencies in theflowfield contribute to the capture of influence regions of vortices and excitation *** concentrated shedding vortices and SJA jets impact region helped to judge that SJA energizes low momentumfluids in a large region and matches the high loss core *** be concrete,theflow separation control mechanism of SJA lies on the interruption of the blade suction surface boundary layer development and the restriction of the lifting of the boundary layer from end-wall towards blade suction surface.

关键词： Compressor cascade Activeflow control Sweeping jet actuator Corner separation Oilflow visualization

APPLICATION OF SOME PHOSPHORUS REAGENTS IN MANNICH-TYPE REACTION

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Chinese Chemical Letters 1995年第7期6卷 561-564页

作者： chen, RY Dai, q Nankai Univ Inst Elementoorgan Chem Tianjin 300071 Peoples R China

Some phosphorus reagents were applied to the Mannich-type reaction of carbamate and p-toluenesulfonamide so that some important intermediates for the synthesis of phosphonopeptides were obtained easily. The structures...

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Novel method for random vibration analysis of single-degree-of-freedom vibroimpact systems with bilateral barriers

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Applied Mathematics and Mechanics(English Edition) 2019年第12期40卷 1759-1776页

作者： Lincong chen Haisheng ZHU J.q.SUN College of Civil Engineering Huaqiao UniversityXiamen 361021Fujian ProvinceChina School of Engineering University of CaliforniaMercedCA 95343U.S.A

The vibroimpact systems with bilateral barriers are often encountered in ***,the dynamics of the vibroimpact system with bilateral barriers is full of *** closed-form solutions were *** this paper,we propose a novel method for random vibration analysis of single-degree-of-freedom(SDOF)vibroim-pact systems with bilateral barriers under Gaussian white noise excitations.A periodic approximate transformation is employed to convert the equations of the motion to a con-tinuous *** probabilistic description of the system is subsequently defined through the corresponding Fokker-Planck-Kolmogorov(FPK)*** closed-form station-ary probability density function(PDF)of the response is obtained by solving the reduced FPK equation and using the proposed iterative method of weighted residue together with the concepts of the circulatory probability flow and the potential probability ***,the versatility of the proposed approach is demonstrated by its application to two typical *** that the solution obtained by using the proposed method can be used as the benchmark to examine the accuracy of approximate solutions obtained by other methods.

关键词： bilateral barrier vibroimpact system weighted residue method iterative random vibration

THE PREPARATION AND CHARACTERISTICS STUDY OF TiN_xO_y SPECTRAL SELECTIVE ABSORBING FILM BY MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 385-388页

作者： D.chen H.Shen B.w.wang H.q.wang MaterialandScienceEngineeringInstitute SouthChinaUniversityofTechnologyGuangzhou510641China EnergyEngineeringInstitute ZhongshanUniversityGuangzhou510275China／／GuangzhouInstituteofEnergyConversionTheChineseAcademyofSciencesGuangzhou510640China GuangzhouInstituteofEnergyConversion TheChineseAcademyofSciencesGuangzhou510640China SchoolofMechanismandAutomobile ShenyangInstituteofAeronauticalEngineeringShenyang110034China

Spectral selective absorbent film is a crucial factor for the solar heating devi ce. There are many kinds of spectral selective absorbing film made by different ways. TiNxOy thin film with excellent spectral selecting absobent property were successfully prepared by DC magnetron sputtering with Ar as working gas, N2 and O2 as reactive gas, 99.9% titanium as the target and is copper slice as the subs trate. In this article, the optical characteristics and microstructure of TiNxO y thin film were studied. Inputing O2 can decrease the reflection of the visible lights, and double layer film can get good absorption for solar energy.

关键词： spectrum selecting absorbent film TiNxOy magnetron sputtering

A highly-efficient method for stationary response of multi-degree-of-freedom nonlinear stochastic systems

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Applied Mathematics and Mechanics(English Edition) 2020年第6期41卷 967-982页

作者： Lincong chen J.q.SUN College of Civil Engineering Huaqiao UniversityXiamen 361021Fujian ProvinceChina Key Laboratory for Intelligent Infrastructure and Monitoring of Fujian Province Jimei Avenue 668Xiamen 361021Fujian ProvinceChina Department of Mechanical Engineering School of EngineeringUniversity of CaliforniaMercedCA 95343U.S.A.

Analytical and numerical studies of multi-degree-of-freedom(MDOF) nonlinear stochastic or deterministic dynamic systems have long been a technical *** paper presents a highly-efficient method for determining the stationary probability density functions(PDFs) of MDOF nonlinear systems subjected to both additive and multiplicative Gaussian white noises. The proposed method takes advantages of the sufficient conditions of the reduced Fokker-Planck-Kolmogorov(FPK) equation when constructing the trial solution. The assumed solution consists of the analytically constructed trial solutions satisfying the sufficient conditions and an exponential polynomial of the state variables, and delivers a high accuracy of the solution because the analytically constructed trial solutions capture the main characteristics of the nonlinear system. we also make use of the concept from the data-science and propose a symbolic integration over a hypercube to replace the numerical integrations in a higher-dimensional space, which has been regarded as the insurmountable difficulty in the classical method of weighted residuals or stochastic averaging for high-dimensional dynamic systems. Three illustrative examples of MDOF nonlinear systems are analyzed in detail. The accuracy of the numerical results is validated by comparison with the Monte Carlo simulation(MCS) or the available exact solution. Furthermore, we also show the substantial gain in the computational efficiency of the proposed method compared with the MCS.

关键词： stationary response multi-degree-of-freedom(MDOF)nonlinear system Fokker-Planck-Kolmogorov(FPK)equation least square method