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Science China(Technological Sciences) 2015年第2期58卷 381-389页

作者： ZHU fu yun ZHANG xiao Sheng ZHANG Hai xia National Key Laboratory of Nano/Micro Fabrication Technology Institute of Microelectronics Peking University

This paper reports a controllable multi-functional black silicon surface with nanocone-forest structures fabricated by an optimized deep reactive ion etching(DRIE)technique using SF6/C4F8 in cyclic etching-passivation process,which is maskless,effective and *** process conditions are investigated by systematically comparative experiments and core parameters have been figured out,including etching process parameters,pre-treatment,patterned silicon etching and inclined surface *** on the experimental data,the formation mechanism of nanocone shape is developed,which provides a novel view for in-depth understanding of abnormal phenomena observed in the experiments under different process *** the optimization of the process parameters,the black silicon surfaces exhibit superhydrophobicity with tunable ***,the quantitative relationship between nanocones aspect ratio and surface reflectance and static contact angle is obtained,which demonstrates that black silicon surfaces with unique functional properties(i.e.,cross-combination of reflectance and wettability)can be achieved by controlling the morphology of nanostructures.

关键词： formation mechanism black silicon nanocone-forest deep reactive ion etching (DRIE) properties characterization

Multi-level virtual prototyping of electromechanical actuation system for more electric aircraft

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Chinese Journal of Aeronautics 2018年第5期31卷 892-913页

作者： Jian fu Jean-Charles MARE Liming yu Yongling fu School of Mechanical Engineering and Automation Beihang University Institut Clement Ader (CNRS UMR 5312) INSA-Toulouse Flying College Beihang University

Electromechanical actuators（EMAs） are becoming increasingly attractive in the field of more electric aircraft because of their outstanding benefits, which include reduced fuel burn and maintenance cost, enhanced system flexibility, and improved management of fault detection and isolation. However, electromechanical actuation raises specific issues when being used for safetycritical aerospace applications like flight controls： huge reflected inertia to load, jamming-type failure, and increase of backlash with service due to wear and local dissipation of heat losses for thermal balance. This study proposes an incremental approach for virtual prototyping of EMAs. It is driven by a model-based system engineering process in order to enable simulation-aided *** practices supported by Bond graph formalism are suggested to develop a model＇s structure efficiently and to make the model ready for use（or extension） by addressing the above mentioned issues. Physical effects are progressively introduced, and the realism of lumped-parameter models is increased step-by-step. In particular, multi-level component models are architected to ensure continuity between engineering activities. The models are implemented in the AMESim simulation environment, and simulation responses are given to illustrate how they can be used for preliminary sizing, control design, thermal balance verification, and faults to failure analysis. The proposed best practices intend to provide engineers with fast, reusable, and efficient means to assess performance virtually and enhance maturity, performance, and robustness.

关键词： Bond graph Electromechanical actuator Flight control Model-based system engi-neering More electric aircraft Power-by-wire

Control for a Class of Stochastic Mechanical Systems Based on the Discrete-Time Approximate Observer

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Journal of Systems Science & Complexity 2019年第2期32卷 526-541页

作者： fu Xinxin KANG yu LI Pengfei yu Peilong Department of Automation University of Science and Technology of China

This paper investigates the observer-based control problem of a class of stochastic mechanical systems. The system is modelled as a continuous-time It o stochastic differential equation with a discrete-time output. Euler-Maruyama approximation is used to design the discrete-time approximate observer, and an observer-based feedback controller is derived such that the closed-loop nonlinear system is exponentially stable in the mean-square sense. Also, the authors analyze the convergence of observer error when the discrete-time approximate observer servers as a state observer for the exact system. Finally, a simulation example is used to demonstrate the effectiveness of the proposed method.

关键词： Approximate model discrete-time observer exponential stability stochastic nonlinear system

Microwave-assisted in situ synthesis of fluorescent gold nanoclusters with BSA/montmorillonite and application on latent fingermark imaging

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Science China Chemistry 2018年第5期61卷 619-626页

作者： Lei Yan Yanlin yu Zhining xia Forensic Science Engineering Research Center of Universities in Chongqing School of Criminal Investigation Southwest University of Political Science and Law School of Bioengineering Chongqing University

A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences.

关键词： gold nanoclusters in situ montmorillonite latent fingermark fluorescent powder forensic science

Modular synthesis of a block copolymer with a cleavable linkage via “click” chemistry

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Science China Chemistry 2010年第5期53卷 1127-1132页

作者： fu, yu Liu, GuoJun Research Centre for Molecular Science and Engineering Northeastern University Shenyang 110004 China Department of Chemistry Queen's University Ontario Canada

A diblock copolymer poly(ethylene glycol)-block-polystyrene or PEG-b-PS with an olefinic double bond at the PEG and PS junction has been prepared by modular synthesis via"click"*** involved the synthesis of PS by atom transfer radical polymerization and the nucleophilic substitution of the terminal bromide group with azide to yield azide-terminated PS. PEG with an alkynyl terminal group was prepared from reacting carboxyl-end-functionalized PEG with 4-hydroxybut-2-enyl prop-2-ynyl succinate,which contained an alkynyl group as well as an olefin *** PS and PEG polymers were linked via the 1,3-dipolar cycloaddition of the end azide and alkyne *** obtained copolymer was characterized by 1H NMR spectroscopy and size exclusion chromatography(SEC).SEC analysis indicated that the diblock copolymer produced could be readily cleaved by ozonolysis to regenerate the constituent homopolymers.

关键词： modular synthesis cleavable block copolymer click chemistry ATRP

Efficient hybrid neural network for spike sorting

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Journal of Systems Engineering and Electronics 2013年第1期24卷 157-164页

作者： Hongge Li Pan yu Tongsheng xia School of Electronics Information Engineering Beihang University

Artificial neural network has been used successfully to develope the automatic spike extraction. In order to address some of the problems before the wireless transmission of the implantable chip, the automatic spike sorting method with low complexity and high efficiency is proposed based on the hybrid neural network with the principal component analysis network （PCAN） and normal boundary response （NBR） self-organizing mapping （SOM） net- work classifier. An automatic PCAN technique is used to reduce the dimension and eliminate the correlation of the spike signal. The NBR-SOM network performs the spike sorting challenge and improves the classification performance. The experimental results show that based on the hybrid neural network, the spike sorting method achieves the accuracy above 97.91% with signals contain- ing five classes. The proposed NBR-SOM network classifier is to further improve the stability and effectiveness of the classification system.

关键词： neural network spike sorting implantable microsys-tern.

Forest type identification by random forest classification combined with SPOT and multitemporal SAR data

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Journal of Forestry Research 2018年第5期29卷 1407-1414页

作者： Ying yu Mingze Li yu fu School of Forestry Northeast Forestry University

We developed a forest type classification technology for the Daxing＇an Mountains of northeast China using multisource remote sensing data.A SPOT-5 image and two temporal images of RADARSAT-2 full-polarization SAR were used to identify forest types in the Pangu Forest Farm of the Daxing＇an *** types were identified using random forest（RF） classification with the following data combination types： SPOT-5 alone,SPOT-5 and SAR images in August or November,and SPOT-5 and two temporal SAR *** identified many forest types using a combination of multitemporal SAR and SPOT-5 images,including Betula platyphylla,Larix gmelinii,Pinus sylvestris and Picea koraiensis *** accuracy of classification exceeded 88% and improved by 12% when compared to the classification results obtained using SPOT data *** classification using a combination of multisource remote sensing data improved classification accuracy compared to that achieved using single-source remote sensing data.

关键词： Random forest classification Multitemporal Multisource remote sensing data Polarization decomposition

Research on the Low-carbon Cementitious Materials:Effect of Triisopropanolamine on the Hydration of Phosphorous Slag and Steel Slag

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1348-1359页

作者： ZHANG Ting MA Baoguo xia yu State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China School of Surveying&Testing Shaanxi Railway InstituteWeinan 714000China

Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration *** experimental results show that,by using 0.06%TIPA,the compressive strength of cement containing 60%PS or 60%SS could be enhanced by 12%or 18%at 28 *** presence of TIPA significantly affected the hydration process of PS and SS in *** the early stage,TIPA accelerated the dissolution of Al in PS,and the formation of carboaluminate hydrate was facilitated,which could induce the hydration;TIPA promoted the dissolution of Fe in SS,and the formation of Fe-monocarbonate,which was precipitated on the surface of SS,resulting in the postponement of hydration,especially for the high SS *** the later stage,under the continuous solubilization effect of TIPA,the hydration of PS and SS could refine the pore *** was noted that compared with portland cement,the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52%and 49%,respectively.

关键词： phosphorous slag steel slag high content trisopropanolamine hydration process lowcarbon emissions

Towards imbalanced motion:part-decoupling network for video portrait segmentation

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Science China(Information Sciences) 2024年第7期67卷 197-210页

作者： Tianshu yu Changqun xia Jia LI State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and EngineeringBeihang University Peng Cheng Laboratory

Video portrait segmentation(VPS), aiming at segmenting prominent foreground portraits from video frames, has received much attention in recent years. However, the simplicity of existing VPS datasets leads to a limitation on extensive research of the task. In this work, we propose a new intricate large-scale multi-scene video portrait segmentation dataset MVPS consisting of 101 video clips in 7 scenario categories,in which 10843 sampled frames are finely annotated at the pixel level. The dataset has diverse scenes and complicated background environments, which is the most complex dataset in VPS to our best *** the observation of a large number of videos with portraits during dataset construction, we find that due to the joint structure of the human body, the motion of portraits is part-associated, which leads to the different parts being relatively independent in motion. That is, the motion of different parts of the portraits is imbalanced. Towards this imbalance, an intuitive and reasonable idea is that different motion states in portraits can be better exploited by decoupling the portraits into parts. To achieve this, we propose a part-decoupling network(PDNet) for VPS. Specifically, an inter-frame part-discriminated attention(IPDA)module is proposed which unsupervisedly segments portrait into parts and utilizes different attentiveness on discriminative features specified to each different part. In this way, appropriate attention can be imposed on portrait parts with imbalanced motion to extract part-discriminated correlations, so that the portraits can be segmented more accurately. Experimental results demonstrate that our method achieves leading performance with the comparison to state-of-the-art methods.

关键词： video portrait segmentation imbalanced motion unsupervised part decoupling motion correlation inter-frame attention

Atomic layer deposition of zinc oxide onto 3D porous iron scaffolds for bone repair:in vitro degradation,antibacterial activity and cytocompatibility evaluation

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Rare Metals 2022年第2期41卷 546-558页

作者： yu-Lei Li Jin He Hai-xia Ye Can-Can Zhao Wei-Wei Zhu Xiong Lu fu-Zeng Ren Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Institute of Applied Physics and Materials Engineering Faculty of Science and TechnologyUniversity of MacaoMacao 999078China Key Lab of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China

3D porous iron(Fe)scaffolds with interconnected open pores are promising candidates for bone ***,the bare 3D porous Fe scaffolds lack of antibacterial activity and the ability for cell ***,atomic layer deposition technique was used to deposit nanometer-thick zinc oxide(ZnO)layer onto the skeleton of 3D porous Fe scaffolds with interconnected open *** effect of ZnO thin film on the in vitro degradation behavior,antibacterial activity and cytocompatibility of 3D porous Fe scaffolds was systematically *** results showed that a dense ZnO thin film with a thickness of 76 nm was uniformly deposited on the skeleton of the porous Fe *** thickness of ZnO thin film could be easily controlled by the deposition *** deposited ZnO thin film significantly reduced the degradation rate of porous Fe scaffolds and the fabricated ZnO coated porous Fe scaffolds demonstrated strong antibacterial ability against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus,while did not significantly affect cytocompatibility and could also promote cell adhesion.

关键词： Atomic layer deposition Porous iron scaffolds ZnO Antibacterial activity