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Semi-analytic solution of Eringen's two-phase local/nonlocal model for Euler-Bernoulli beam with axial force

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1805-1824页

作者： Licheng MENG Dajun ZOU Huan LAI Zili GUO Xianzhong HE Zhijun XIE Cunfa GAO Facility Design and Instrumentation Institute China Aerodynamics Research and Development Center State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Eringen’s two-phase local/nonlocal model is applied to an Euler-Bernoulli nanobeam considering the bending-induced axial force, where the contribution of the axial force to bending moment is calculated on the deformed state. Basic equations for the corresponding one-dimensional beam problem are obtained by degenerating from the three-dimensional nonlocal elastic equations. Semi-analytic solutions are then presented for a clamped-clamped beam subject to a concentrated force and a uniformly distributed load, respectively. Except for the traditional essential boundary conditions and those required to be satisfied by transferring an integral equation to its equivalent differential form, additional boundary conditions are needed and should be chosen with great caution, since numerical results reveal that non-unique solutions might exist for a nonlinear problem if inappropriate boundary conditions are used. The validity of the solutions is examined by plotting both sides of the original integro-differential governing equation of deflection and studying the error between both sides. Besides, an increase in the internal characteristic length would cause an increase in the deflection and axial force of the beam.

关键词： nonlocal elasticity internal characteristic length size effect nanobeam axial force unique solution

Super-resolution DOA estimation for correlated off-grid signals via deep estimator

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Journal of Systems Engineering and Electronics 2022年第6期33卷 1096-1107页

作者： WU Shuang YUAN Ye ZHANG Weike YUAN Naichang Facility Design and Instrumentation Institute China Aerodynamics Research and Development CenterMianyang 621000China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System National University of Defense TechnologyChangsha 410073China

This paper develops a deep estimator framework of deep convolution networks(DCNs)for super-resolution direction of arrival(DOA)estimation.In addition to the scenario of correlated signals,the quantization errors of the DCN are the major challenge.In our deep estimator framework,one DCN is used for spectrum estimation with quantization errors,and the remaining two DCNs are used to estimate quantization errors.We propose training our estimator using the spatial sampled covariance matrix directly as our deep estimator’s input without any feature extraction operation.Then,we reconstruct the original spatial spectrum from the spectrum estimate and quantization errors estimate.Also,the feasibility of the proposed deep estimator is analyzed in detail in this paper.Once the deep estimator is appropriately trained,it can recover the correlated signals’spatial spectrum fast and accurately.Simulation results show that our estimator performs well in both resolution and estimation error compared with the state-of-the-art algorithms.

关键词： off-grid direction of arrival(DOA)estimation deep convolution network(DCN) correlated signal quantization error super-resolution

Tandem catalysis for enhanced CO oxidation over the Bi-Au-SiO_(2)interface

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Nuclear Science and Techniques 2023年第7期34卷 198-205页

作者： Huan Zhang Lei Xie Zhao-Feng Liang Chao-Qin Huang Hong-Bing Wang Jin-Ping Hu Zheng Jiang Fei Song instrumentation and Service Center for Physical Sciences Westlake UniversityHangzhou 310024China Shanghai Synchrotron Radiation facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China Shanghai institute of Applied Physics Chinese Academy of SciencesShanghai 201800China

Bimetallic catalysts typically exploit unique synergetic effects between two metal species to achieve their catalytic effect.Understanding the mechanism of CO oxidation using hybrid heterogeneous catalysts is important for effective catalyst design and environmental protection.Herein,we report a Bi-Au/SiO_(2)tandem bimetallic catalyst for the oxidation of CO over the Au/SiO_(2)surface,which was monitored using near-ambient-pressure X-ray photoelectron spectroscopy.The Au-decorated SiO_(2)catalyst exhibited scarce activity in the CO oxidation reaction;however,the introduction of Bi to the Au/SiO_(2)system promoted the catalytic activity.The mechanism is thought to involve the dissociation O_(2)molecules in the presence of Bi,which results in spillover of the O species to adjacent Au atoms,thereby forming Au^(δ+).Further CO adsorption,followed by thermal treatment,facilitated the oxidation of CO at the Au-Bi interface,resulting in a reversible reversion to the neutral Au valence state.Our work provides insight into the mechanism of CO oxidation on tandem surfaces and will facilitate the rational design of other Au-based catalysts.

关键词： APXPS CO oxidation Au-Bi interface Tandem catalysis In situ

Inversion Control of Aircraft Herbst Maneuver with Nonlinear Dynamic Root-finding

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Inversion Control of Aircraft Herbst Maneuver with Nonlinear...

Numerical solutions of 2-D steady compressible natural convection using high-order flux reconstruction

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作者： Sheng Zhang Fei Liao Weiqi Qian Kaifeng He Computational Aerodynamics institute China Aerodynamics Research and Development Center China State Key Laboratory of Aerodynamics Facility Design and Instrumentation Institute China Aerodynamics Research and Development Center

Root-finding techniques may be utilized in designing the controller, and the heavy numerical iteration brought by the conventional methods is unappealing. A nonlinear Dynamic Root-finding（DRF） technique is developed and embedded in the time-scale separation based Dynamic Inversion（DI） controller to realize the aircraft Herbst post-stall maneuver. Different from the conventional root-finding methods, the proposed method is derived from the dynamics stability theory. The employment of this method makes the control logic fairly simple and the resulting controller is of appealing integral form. Under reasonable assumptions, the stability of the further developed DI control system is guaranteed. Simulation results verify the DRF method’s efficiency, precision and reliability in solving the state-dependent nonlinear implicit algebraic equation. This technique may be applied to other control problems.

关键词： Aircraft flight control Post-stall maneuver Herbst maneuver Dynamic inversion Dynamic root-finding

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Acta Mechanica Sinica 2019年第2期35卷 401-410页

作者： Yaojie Yu Feng Liu Tingbo Zhou Chao Gao Ya Liu National Key Laboratory of Aerodynamic design and Research Northwestern Polytechnical UniversityXi’an 710072 China Department of Mechanical and Aerospace Engineering University of California Irvine Irvine CA 92697 USA Facility Design and Instrumentation Institute China Aerodynamics Research and Development CenterMianyang 621000 China

Low Mach number flows are common and typical in industrial applications. When simulating these flows, performance of traditional compressible flow solvers can deteriorate in terms of both efficiency and accuracy. In this paper, a new high-order numerical method for two-dimensional(2-D)state low Mach number flows is proposed by combining flux reconstruction(FR)and preconditioning. Firstly, a Couette flow problem is used to assess the efficiency and accuracy of preconditioned FR. It is found that the FR scheme with preconditioning is much more efficient than the original FR scheme. Meanwhile,this improvement still preserves the numerical accuracy. Using this new method and without the Boussinesq assumption,classic natural convection is directly simulated for cases of small and large temperature differences. For the small temperature difference, a p and h refinement study is conducted to verify the grid convergence and accuracy. Then, the influence of the Rayleigh number (Ra) is analyzed. By comparing with the reference results, the numerical results of preconditioned FR is very close to that calculated by incompressible solvers. Furthermore, a large temperature difference test case is calculated and analyzed, indicating this method is not limited by the Boussinesq assumption and is also applicable to heat convection with large temperature differences.

关键词： Flux reconstruction Preconditioning method Low Mach flows Natural convection

Quantitative temperature imaging at elevated pressures and in a confined space with CH4/air laminar flames by filtered Rayleigh scattering

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Chinese Physics B 2020年第2期29卷 315-320页

作者：闫博陈力李猛陈爽龚诚杨富荣吴运刚周江宁母金河 Science and Technology on Scramjet Laboratory Hypervelocity Aerodynamics InstituteChina Aerodynamics Research and Development CenterMianyang 621000China Facility Design and Instrumentation Institute China Aerodynamics Research and Development CenterMianyang 621000China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractions are obtained through the detailed numerical simulations.And this approach can be used to correct the FRS images of large variations in a Rayleigh cross section in different flame regimes.The temperature distribution above the flat burner is then presented without stray light interference from soot and wall reflection.Results also show that the extent of agreement with the single point measurement by the thermocouple is<6%.Finally,this study concludes that the relative uncertainty of the presented filtered Rayleigh scattering diagnostics is estimated to be below 10%in single-shot imaging.

关键词： filtered Rayleigh scattering high-pressure combustion simulator temperature measurement

Studies on metals and pesticide content in some Ayurvedic formulations containing Bacopa monnieri L.

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Journal of Integrative Medicine 2016年第1期14卷 44-50页

作者： Amrita Mishra Arun K.Mishra Om Prakash Tiwari Shivesh Jha Central facility of instrumentation School of Pharmaceutical SciencesIFTM University Department of Pharmaceutical Sciences Birla Institute of Technology

OBJECTIVE： Ayurvedic formulations are preferred over other formulations as well as commercialized on broad level to treat various ailments. The World Health Organization has established certain guidelines for quality control of heavy metals and pesticide residues. Bacopa monnieri, a popular herb with immunomodulator and memory-enhancing properties is the chief constituent of several Ayurvedic formulations, which include Brahmi Vati （BV）, Brahmi Ghrita （BG） and Saraswat Churna （SC）, etc. In view of the World Health Organization guidelines, two products of each formulation from six different manufacturers were purchased from Ayurvedic Pharmacy, Bulanala-Varanasi, India for testing heavy metal and pesticide residue. METHODS： In the present study, all the formulations--BY, BG and SC--were selected for estimation of four heavy metals namely lead （Pb）, cadmium （Cd）, chromium （Cr） and nickel （Ni） by a plasma emission spectrophotometer. Organochlorine pesticidal residues were estimated for dichlorodiphenyl trichloroethane, isomers of hexachlorocyclohexane （HCH） and a-endosulfan, etc. in total 12 samples of test formulations containing Bacopa monnieri L. using gas chromatography technique. RESULTS： Out of 12 samples, Pb, Cd, Cr and Ni were present in all samples but below the permissible limit. Although atrazine, aldrin, dialdrin were in below detection limit, but other pesticides were detected in some samples as oxamyl, hexachlorocyclohexanes （α-HCH, β-HCH and y-HCH）, dichlorodiphenyl trichloroethane and dichlorodiphenyl dichloroethylene. CONCLUSION： The presence of heavy metals in evaluation of heavy metals and pesticide residue the formulations was low to cause toxicity. However n every batch is necessary.

关键词： Ayurvedic formulations heavy metals pesticide residues drug contamination

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低速风洞轴流风扇研制进展

风机技术 2022年第6期64卷 68-73页

作者：杨高强张海洋屈晓力 facility design and Instrument institute China Aerodynamics Research and Development Center

CARDC(China Aerodynamics Research and Development Center)has designed and developed various kinds of axial fans for specific wind tunnels in the previous decade.This paper not only gives summary about it,but also talks its future development.First,the contents are presented about high aerodynamic performance low-noise fan,including the methods of designing fan and ways of controlling noise generation and propagation,and how to reconcile the difficulties between noise control and fan efficiency raise.Then a simplified method of adjusting fan-blade angle during commissioning test is proposed and validated in practice.Contrary to usually used method,this simplified method can be implemented without using any test instruments of the fan,thus significantly reducing the commissioning test time of the fan.This is followed by the design of high pressure low Reynolds number axial fan.By using the method discussed in the paper,the restriction of Ma at blade tip not higher than 0.5 is relaxed.Accordingly,the pressure ratio obtained through one stage fan was raised above to 1.08,realizing the design target of Ma as 0.7 of the air in the test section.In addition,the topics about fan array,low hub-tip ratio fan and high pressure fan have been briefly covered for the future work.

关键词： Axial Fan HighAerodynamic Performance LowNoise Fan-bladeAngle WindTunnel

Online coal dust suppression system for opencast coal mines

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International Journal of Coal Science & Technology 2023年第5期10卷 178-186页

作者： Senju Panicker S.S.Shankar S.Jithin S.Sandeep Muhammed Irshad Jerry Daniel Tarique Sajad Control and instrumentation Group Centre for Development of Advanced ComputingThiruvananthapuramKeralaIndia Mining Electronics Department Central Mine Planning and Design InstituteRanchiJharkhandIndia

Coal is the major source of power in India and world over.Coal mining is an essential industry which has a major role in the economic development of the country.Most major mining activities contribute directly or indirectly to air pollution.Coal dust is a major air pollutant which affects the personal working in the mines and also people residing in villages near the mines.Air pollution due to coal particulates can affect human health and cause damages to the environment.Hence effective pollution control mechanisms are needed to keep the pollution levels within permissible levels.The easiest and most common method employed for dust suppression worldwide is sprinkling of water.In majority of mines,water sprinklers are operated manually and can lead to wastage of water due to over sprinkling.It can also prove to be ineffective in dust suppression if sprinkling is not done properly.The paper proposes a system which can be deployed to automate the dust suppressions sprinklers.The system will monitor the concentration of PM_(10) and PM_(2.5) in the air and initiate sprinkling operation when the particulate matter content exceeds preconfigured limits.

关键词： Coal dust Dust suppression Sprinkling Automation Particulate matter PMio-PM2.5