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Analysis of the Internal Characteristics of a De ector Jet Servo Valve

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 180-192页

作者： hao Yan Yukai ren Lei Yao Lijing Dong School of Mechanical Electronic and Control Engineering Beijing Jiaotong University

In current research on deflector jet servo valves, the receiver pressure estimated using traditional two-dimensional simulation and theoretical calculation is always lower than the experimental data; therefore, credible information about the flow field in the prestage part of the valve can hardly be obtained. To investigate this issue and understand the internal characteristics of the deflector jet valve, a realistic numerical model is constructed and a three-dimensional simulation carried out that displays a complex flow pattern in the deflector jet structure. Then six phases of the flow pattern are presented, and the defects of the two-dimensional simulation are revealed. Based on the simulation results, it is found that the jet in the deflector has a longer core area and the fluid near the shunt wedge cannot resist the impact of the high-speed fluid. Therefore, two assumptions about the flow distribution are presented by which to construct a more complete theoretical model. The receiver pressure and prestage pressure gain are significantly enhanced in the calculations. Finally, special experiments on the prestage of the servo valve are performed, and the pressure performance of the numerical simulation and the theoretical calculation agree well with the experimental data. Finally, the internal mechanism described by the theoretical and numerical models is verified. From this research,more accurate numerical and theoretical models are proposed by which to figure out the internal characteristics of the deflector jet valve.

关键词： Deflector jet Servo valve Computational fluid dynamics(CFD) Numerical simulation

Sensitive detection of dopamine and quinone drugs based on the quenching of the fluorescence of carbon dots

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Science Bulletin 2016年第20期61卷 1615-1623页

作者： Xiangling ren Jiejie Ge Xianwei Meng Xiaozhong Qiu Jun ren Fangqiong tang Laboratory of Controllable Preparation and Application of Nanomaterials Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190China Department of Anatomy Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering Southern Medical University Guangzhou 510515 China

In this work,we demonstrated that the quinone structure can quench the fluorescence of the carbon dots(CDs).The sensitive determination of dopamine(DA) was studied primarily based on this *** would be transformed into DA quinone under alkaline conditions,which resulted in fluorescence quenching of the CDs.A good linear range from 5 nmol/L to 0.4 mmol/L was obtained and the detection limit was 1 nmol/***,the quenching effect of quinone structure on the fluorescence of CDs was confirmed by Fourier transform infrared spectra,time-correlated single-photon counting and X-ray photoelectron ***,CDs were firstly applied to detect the quinone drugs quantitatively which contained typical quinone structure based on the quenching *** than this,the sensing platform was demonstrated to provide credible selectivity and satisfactory stability in human serum solution with good liner ***,our practical application and mechanism have showed great potential for diagnostic purposes.

关键词： Carbon dots Quinone structure Detection Dopamine Quinone drugs

Failure behavior of cellular titanium under dynamic loading

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Science China(Technological Sciences) 2017年第4期60卷 613-623页

作者： ren HuiLan WANG Jing hao Li SHEN HaiTing State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology School of Sciences Beijing University of Civil Engineering and Architecture

The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the material. Dynamic compression experiments are conducted at room temperature using a single-stage light gas gun. The Hugoniot relations between shock wave velocity and particle velocity for the cellular titanium samples with porosities 20% and 30% are obtained. The shock response of the regular cellular titanium shows a clear wave attenuation effect. Numerical simulations are also conducted to supplement the experimental *** deformation is observed in the samples using optical micrographs, indicating that the deformation of pores contributes significantly to the shock wave attenuation of the cellular titanium material.

关键词： plate impact cellular titanium Hugoniot relation dynamic compression

Ripple-based matrix modeling and cross-coupling effect analysis of double-input DC-DC Boost converters

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Science China(Technological Sciences) 2022年第8期65卷 1878-1890页

作者： ZHANG hao ren Han YI ChuanZhi DONG DaChu State Key Lab of Electrical Insulation&Power Equipment School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China Bosch Automotive Product(Suzhou)Co.Ltd Suzhou 215000China Hangzhou Power Supply Company of State Grid Zhejiang Electric Power Co.Ltd Hangzhou 310000China

This paper deals with the modeling and cross-coupling effect analysis in double-input Boost converters with multiplex current control. A ripple-based multiplex current controlled matrix model is proposed to restore the system's high-frequency domain dynamics information and resolve the coexistence problem of the sample-and-hold effect in multiplex current controllers, which significantly improves the resolution of the conventional average model. Based on the proposed model, both sub-harmonic and low-frequency oscillations are identified in terms of stability analysis, and the inherent mechanism of these complicated nonlinear dynamic behavior is revealed, which not only illustrates the origin of the oscillations but also points out the dominant factors in diverse types of instability situation. Besides, cross-coupling effect analysis is performed to study the interaction between the input ports with the help of the Gershgorin band, and the mechanism of the special unbalanced oscillation phenomenon is revealed. Furthermore, the sensitivity analysis approach is used to identify the key parameters with respect to the cross-coupling effect, which provides more design-oriented knowledge for practical engineering. In addition, the benefits of the proposed model are further illustrated through a comparative analysis. Finally, these theoretical results are verified by experimental ones. These results are beneficial to the improvement of performance as well as the understanding of the cross-coupling effect of multi-input converters.

关键词： ripple-based matrix model cross-coupling effect multiplex current control multi-input converter Gershgorin band

Flotation of niobite,fersmite,and ilmenorutile

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 249-254页

作者： hao ren Gui-lan Song Fei-fei Ji School of Chemistry and Chemical Engineering University of Jinan Jinan 250022 China

The flotation ofniobite, fersmite, and ilmenorutile was studied using 3 collectors with various concentration and pulp pH. The collecting property of different representative collectors was investigated. Experimental results show that diphosphonic acid is an effective collector for valuable niobium-containing minerals. A flotation recovery of 90.87%-91.7% is obtained with 75 mg/L diphosphonic acid at pH 2-4. The chemical adsorption of diphosphonic acid on these 3 minerals＇ surface might lead to the high recovery efficiency of the minerals, which is proved by IR and X-ray photoelectron spectroscopy spectra.

关键词： flotation collector diphosphonic acid niobite fersmite ilmenorutile

Constructing 2D bismuth-based heterostructure for highly efficient photocatalytic CO2 reduction

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Tungsten 2025年第1期 71-79页

作者： Ruo-Hang Xu hao-Yu Jiang Dan-Dan Cui Kun-Rong Du Hong-Run Zhang Sheng-Jie Xu Ya-Qi Li Zhi-Zhen ren Liang Wang Wei-Chang hao Yi Du School of Physics and BUAA-UOW Joint Research Centre Beihang University Shenzhen Institute of Beihang University Centre for Catalysis and Clean Energy School of Environment and Science Griffith University

Reforming carbon dioxide（CO2） into fuels and valuable chemicals using solar energy holds significant potential for emission reduction and addressing energy supply *** recombination of photocarriers remains a major obstacle,however,to enhancing solar energy conversion efficiency in the photocatalytic reaction *** two-dimensional materials,constructing heterogeneous structures has emerged as an effective strategy to enhance the separation of photoexcited carriers by leveraging the internal electric field at the heterogeneous ***,we present a facile strategy for preparing Bi4NbO8Br/Bi2WO6plate-on-plate Z-scheme junctions with a strong internal electric field by in situ *** unique heterostructure facilitates efficient separation and transport of photoexcited charges by harnessing the internal electric field induced by chemical bonding at the lateral ***,the Bi4NbO8Br/Bi2WO6heterostructure exhibits enhanced CO2photoreduction properties,along with a CO yield rate of approximately 35 μmol·g-1·h-1under full light *** work offers novel insights into the synthesis of unique hetero structures intended to enhance the efficiency of photocatalytic CO2reduction.

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TIO: A VLC-Enabled Hybrid Data Center Network Architecture

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Tsinghua Science and Technology 2019年第4期24卷 484-496页

作者： Yudong Qin Deke Guo Guoming tang Bangbang ren the Science and Technology on Information System Engineering Laboratory National University of Defense Technology

To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks(DCNs), which employ high-bandwidth Optical Circuit Switches(OCSs) to compensate for Electrical Packet Switches(EPS). Existing designs, such as Helios and c-Through, mainly focus on reconfiguring optical devices to meet the estimated traffic requirements. However, these designs face two major challenges in their OCS-based networks, namely, the complex control mechanism and cabling problems. To solve these challenges, we propose TIO, a hybrid DCN that employs Visible Light Communication(VLC) instead of wired OCS design to connect racks. TIO integrates the wireless VLC-based Jellyfish and wired EPS-based Fat Tree seamlessly and combines the opposite and complementary characteristics, including wireless VLC direct connection and wired electrical packet switching, random graph, and Clos topology properties. To further exploit the merits of TIO, we design a hybrid routing scheme and congestion-aware flow scheduling method. Comprehensive evaluations indicate that TIO outperforms the Jellyfish and Fat Tree in both topology properties and network performance, and the flow scheduling method also evidently improves performance.

关键词： Data Center Network(DCN) visible light communication wireless links topology design

Optimal tracking control for linear time-delay large-scale systems with persistent disturbances

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Journal of Systems Engineering and Electronics 2009年第5期20卷 1058-1064页

作者： tang Ruichun Ma Huamin Guo Shuangle ren Lijie Coll. of Information Science and Engineering Ocean Univ. of China Qingdao 266100 P. R. China Huawei Technologies Co. Ltd Shenzhen 518129 P. R. China Coll. of Mathematics and Computer Science Hengshui Univ. Hengshui 053000 P. R. China

An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear two- point boundary value （TPBV） problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.

关键词： optimal tracking control sensitivity approach time-delay large-scale system persistent disturbance,

Finite-Time Neural Funnel Control for Motor Servo Systems with Unknown Input Constraint

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Journal of Systems Science & Complexity 2017年第3期30卷 579-594页

作者： CHEN Qiang tang Xiaoqing NAN Yurong ren Xuemei College of Information Engineering Zhejiang University of Technology School of Automation Beijing Institute of Technology

In this paper, a finite-time neural funnel control(FTNFC) scheme is proposed for motor servo systems with unknown input constraint. To deal with the non-smooth input saturation constraint problem, a smooth non-affine function of the control input signal is employed to approximate the saturation constraint, which is further transformed into an affine form according to the mean-value theorem. A fast terminal sliding mode manifold is constructed by using a novel funnel error variable to force the tracking error falling into a prescribe boundary within a finite time. Then, a simple sigmoid neural network is utilized to approximate the unknown system nonlinearity including the *** from the prescribed performance control(PPC), the proposed finite-time neural funnel control avoids using the inverse transformed function in the controller design, and could guarantee the prescribed tracking performance without knowing the saturation bounds in prior. The effectiveness and superior performance of the proposed method are verified by comparative simulation results.

关键词： Funnel control input constraint neural network servo system.