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Wing optimization of propeller aircraft based on actuator disc method

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Chinese Journal of Aeronautics 2021年第5期34卷 65-78页

作者： yifei zhang Haixin CHEN Yufei zhang School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

Propeller aircraft are widely used in general *** rotating propeller has a strong effect on the aerodynamic performance of the *** paper uses an actuator disc to model the effect of the propeller.A wing optimization method is developed with the actuator disc *** wing optimizations with different slipstream settings are *** twist angle and airfoils of the wing are used as the design *** results show that the propeller slipstream and slipstream directions have a strong influence on the optimization ***-on optimization with a slipstream can obtain better drag reduction results than unpowered *** drag decomposition results show that most of the drag reduction comes from the form drag *** symmetric"inboard-up"slipstream configuration is found to have the highest lift-to-drag ratios,which are 18.87 for the twist angle optimization and 19.15 for the airfoil optimization.

关键词： Propeller Actuators Optimization Aerodynamics Aircraft wings

Moving scanning emitter tracking by a single observer using time of interception:Observability analysis and algorithm

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Chinese Journal of Aeronautics 2017年第3期30卷 1174-1183页

作者： yifei zhang Min zhang Fucheng GUO Information Engineering Department Rocket Force University of Engineering College of Electronic Science and Engineering National University of Defense Technology

The target motion analysis（TMA） for a moving scanning emitter with known fixed scan rate by a single observer using the time of interception（TOI） measurements only is investigated in this *** transforming the TOI of multiple scan cycles into the direction difference of arrival（DDOA） model,the observability analysis for the TMA problem is *** necessary conditions for uniquely identifying the scanning emitter trajectory are *** paper also proposes a weighted instrumental variable（WIV） estimator for the scanning emitter TMA,which does not require any initial solution guess and is closed-form and computationally *** importantly,simulations show that the proposed algorithm can provide estimation mean square error close to the Cramer-Rao lower bound（CRLB） at moderate noise levels with significantly lower estimation bias than the conventional pseudo-linear least square（PLS） estimator.

关键词： Cramer-Rao lower bound Least squares Observability Scanning emitter Target motion analysis Time of interception

Neural mechanisms of feature binding

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Science China(Life Sciences) 2020年第6期63卷 926-928页

作者： yifei zhang Yan-Yu zhang Fang Fang School of Psychological and Cognitive Sciences Peking UniversityBejing 100871China Beijing Key Laboratory of Behavior and Mental Health Peking UniversityBetijing 100871China Key Laboratory of Machine Perception(Ministry of Education) Peking UniversityBetijing 100871China PKU-IDG/Mc Govern Institute for Brain Research Peking UniversityBejing 100871China Peking-Tsinghua Center for Life Sciences Peking UniversityBejing 100871China

An object is usually composed of different features(e.g.,color,orientation,and motion),which are processed by segregated visual pathways and represented by functionally specialized brain ***,we perceive an object as a coherent whole,rather than its isolated *** we integrate those isolated features and achieve a precise perception of objects is a fundamental challenge for the visual system,which is referred to as the binding problem.

关键词： Neural mechanisms of feature binding

The transformation of PAHs in the sewage sludge incineration treatment

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Frontiers of Environmental Science & Engineering 2016年第2期10卷 336-340页

作者： Hui zhang Le XU yifei zhang Mengchan JIANG School of Environmental Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China Environmental Monitoring Center of Songjiang District Shanghai 201600 China

The release of pollutants from sewage sludge in the treatment process is a worldwide tricky problem in the field of sludge treatment. In this paper, the release and reaction between monomers of polycyclic aromatic hydrocarbons （PAHs） in the sewage sludge incineration treatment were studied based on simulated experiments. The result indicates that the transformation may occurre between monomers of PAHs during their release in the treatment. Over 90% of total PAHs in sewage sludge are released at the the temperature of 300℃-750℃. The possible transformation of Naphthalene to indeno（1, 2, 3- cd）pyrene was related to the temperature of the treatment system. Here, we showed that the output rate of transformation reactions for indeno（1, 2, 3-cd）pyrene is 94% at 300℃. These findings, by identifying correspond- ing treatment conditions as well as techniques, can help to understand the reactions and control real outputs of PAHs in the treatment process.

关键词： PAHs sewage sludge incineration treatment,release of monomers transformation of monomers

Individualized Design of the Ventilator Mask based on the Residual Concentration of CO2

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Computer Modeling in Engineering & Sciences 2018年第11期117卷 157-167页

作者： Zhiguo zhang Zhenxiao Li yifei zhang Zhenze Wang Minzhou Luo Jiangsu Key Laboratory of Special Robot Technology College of Mechanical and Electrical EngineeringHohai UniversityNo.200.Jinling North RoadXinbeiChangzhou213022China School of Mechanical Engineering Changzhou UniversityNo.1.Gehu RoadWujinChangzhou213164China School of Mathematics&Physics Changzhou UniversityNo.1.Gehu RoadWujinChangzhou213164China National Research Center for Rehabilitation Technical Aids Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age DisabilityKey Laboratory of Rehabilitation Technical Aids Technology and System of the Ministry of Civil AffairsNo.1.Ronghuazhong RoadBeijing BDABeijing100176China.

OSAHS(Obstructive Sleep Apnea Hypopnea Syndrome)is a respiratory disease mainly characterized by limited and repeated pauses of breathing in ***,the optimal treatment is to apply CPAP(Continuous Positive Airway Pressure)ventilation on the upper airway of the patient through a household respiratory ***,if the ventilator mask is designed improperly,it might cause the residue and repeated inhalation of CO2,which will exert an adverse impact on the therapeutic *** research numerically analyzed the CO2 transportation inside a commercial ventilator mask(Mirage SoftGel,ResMed,Australia)based on the reconstructed 3D numerical model of a volunteer's face and performed the improved design of the ventilator mask in terms of the CO2 residual concentration below the *** fluid dynamic analyses showed that at the end time of expiratory,the CO2 residual concentration below the nostrils is close to 4%.To improve the therapeutic effect,we changed the position of the exhaust holes and found that by moving the exhaust holes to the bottom of the ventilator mask,the CO2 residual concentration below the nostrils would be reduced to no more than 1%.This study established a near physiological computational model and provided a new method for the individualized design of the commercial ventilator mask.

关键词： Obstructive sleep apnea hypopnea syndrome continuous positive airway pressure ventilator mask CO2 residual concentration 3D numerical reconstruction.

A novel cross-modal hashing algorithm based on multimodal deep learning

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Science China(Information Sciences) 2017年第9期60卷 50-63页

作者： Wen QU Daling WANG Shi FENG yifei zhang Ge YU School of Information Science and Engineering Northeastern University Key Laboratory of Medical Image Computing

With the growing popularity of multimodal data on the Web, cross-modal retrieval on large-scale multimedia databases has become an important research topic. Cross-modal retrieval methods based on hashing assume that there is a latent space shared by multimodal features. To model the relationship among heterogeneous data, most existing methods embed the data into a joint abstraction space by linear projections. However,these approaches are sensitive to noise in the data and are unable to make use of unlabeled data and multimodal data with missing values in real-world applications. To address these challenges, we proposed a novel multimodal deep-learning-based hash(MDLH) algorithm. In particular, MDLH uses a deep neural network to encode heterogeneous features into a compact common representation and learns the hash functions based on the common representation. The parameters of the whole model are fine-tuned in a supervised training *** on two standard datasets show that the method achieves more effective results than other methods in cross-modal retrieval.

关键词： hashing cross-modal retrieval cross-modal hashing multimodal data analysis deep learning

Hierarchically porous Co@N-doped carbon fiber assembled by MOF-derived hollow polyhedrons enables effective electronic/mass transport:An advanced 1D oxygen reduction catalyst for Zn-air battery

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Journal of Energy Chemistry 2023年第1期76卷 117-126,I0004页

作者： yifei zhang Quanfeng He Zihao Chen Yuqing Chi Junwei Sun Ding Yuan Lixue zhang Industrial Research Institute of Nonwovens&Technical Textiles College of Textiles&ClothingQingdao UniversityQingdao 266071ShandongChina College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071ShandongChina College of Chemistry and Chemical Engineering Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)Xiamen UniversityXiamen 361005FujianChina

Developing advanced oxygen reduction reaction(ORR)electrocatalysts with rapid mass/electron transport as well as conducting relevant kinetics investigations is essential for energy technologies,but both still face ongoing ***,a facile approach was reported for achieving the highly dispersed Co nanoparticles anchored hierarchically porous N-doped carbon fibers(Co@N-HPCFs),which were assembled by core-shell MOFs-derived hollow ***,the unique one-dimensional(1D)carbon fibers with hierarchical porosity can effectively improve the exposure of active sites and facilitate the electron transfer and mass transfer,resulting in the enhanced reaction *** a result,the ORR performance of the optimal Co@N-HPCF catalysts remarkably outperforms that of commercial Pt/C in alkaline solution,reaching a limited diffusion current density(J)of 5.85 m A cm^(-2)and a half-wave potential(E_(1/2))of 0.831 ***,the prepared Co@N-HPCF catalysts can be used as an excellent air-cathode for liquid/solid-state Zn-air batteries,exhibiting great potentiality in portable/wearable energy ***,the reaction kinetic during ORR process is deeply explored by finite element simulation,so as to intuitively grasp the kinetic control region,diffusion control region,and mixing control region of the ORR process,and accurately obtain the relevant kinetic *** work offers an effective strategy and a reliable theoretical basis for the engineering of first-class ORR electrocatalysts with fast electronic/mass transport.

关键词： Oxygen reduction catalyst Metal-organic frameworks Carbon nanofiber Hierarchically porous structure Diffusion kinetics Zn-air battery

Document structure model for survey generation using neural network

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Frontiers of Computer Science 2021年第4期15卷 73-82页

作者： Huiyan XU Zhongqing WANG yifei zhang Xiaolan WENG ZhijianWANG Guodong ZHOU College of Computer and Information Hohai UniversityNanjing 210098China School of Computer Science and Technology Huaiyin Normal UniversityHuai’an 223300China Natural Language Processing Lab Soochow UniversitySuzhou 215006China

Survey generation aims to generate a summary from a scientific topic based on related *** structure of papers deeply influences the generative process of survey,especially the relationships between sentence and sentence,paragraph and *** principle,the structure of paper can influence the quality of the ***,we employ the structure of paper to leverage contextual information among sentences in paragraphs to generate a survey for *** particular,we present a neural document structure model for survey *** take paragraphs as units,and model sentences in paragraphs,we then employ a hierarchical model to learn structure among sentences,which can be used to select important and informative sentences to generate *** evaluate our model on scientific document data *** experimental results show that our model is effective,and the generated survey is informative and readable.

关键词： survey generation contextual information document structure

Nanostructured Ni-MoCx:An efficient non-noble metal catalyst for the chemoselective hydrogenation of nitroaromatics

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Nano Research 2023年第7期16卷 8919-8928页

作者： yifei zhang Zhiwen Li Jingjing zhang Liangliang Xu Zhong-Kang Han Alfons Baiker Gao Li Institute of Catalysis for Energy and Environment College of Chemistry and Chemical EngineeringShenyang Normal UniversityShenyang 110034China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Department of Chemistry and Applied Biosciences Institute for Chemical and BioengineeringETH ZurichHönggerbergHClZurich CH-8093Switzerland University of Chinese Academy of Sciences Beijing 100049China

Catalysts for chemoselective hydrogenation are of vital importance for the synthesis of various important chemicals and *** we developed a simple method for preparing a highly efficient Ni-MoC_(x)nanocomposite catalyst via temperature-programmed carburization of a polyoxometalate precursor.X-ray diffraction(XRD),scanning transmission electron microscopy(STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS)analyses indicate that the resulting mesoporous nanocomposite catalyst is made up of well-dispersed metallic nickel particles embedded in a MoC_(x)*** catalyst exhibits high activity and selectivity(>99%)in the hydrogenation of various substituted nitroaromatics to corresponding *** high efficiency is attributed to the intimate contact of the constituents favoring electron transfer and hydrogen *** is physisorbed on the carbide support and dissociates on the nickel particles,as evidenced by Mo K-edge X-ray absorption near-edge structure(XANES)spectra,density functional theory(DFT),and hydrogen-deuterium *** remarkable catalytic performance of the catalyst could be traced back to the synergistic interaction between the Ni particles and the carbide ***-situ infrared spectroscopy and DFT simulations indicated that the adsorption/activation of the nitro group is favored compared to that of other substituents at the aromatic *** recyclability tests,the Ni-MoC_(x)nanocomposite showed no significant loss of catalytic performance in seven consecutive runs,indicating its robust nature.

关键词： Ni-MoC_(x)nanocomposite carburization of polyoxometalate hydrogenation nitroaromatics synergistic effect