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Enhanced electrothermal effect of carbon fibrous composites decorated with high conductive carbon nanotube webs

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Chinese Journal of Aeronautics 2021年第11期34卷 243-253页

作者： Bingcheng WANG xu feng Ling LIU School of Aerospace Engineering&Applied Mechanics Tongji UniversityShanghai 200092China

Literature has demonstrated that Carbon Nanotubes(CNTs) can greatly enhance the electrical conductivity and matrix-dominated mechanical properties of fibrous composites. However, electrothermal coupling effect of CNTs on Carbon Fiber Reinforced Plastics(CFRPs) has scarcely been considered. This work prepared and introduced thin and porous CNT webs to the surface or/and interface of a CFRP to enhance its electrothermal properties. The results show that CNT webs can enhance the transverse electrical conductivities of the CFRP by 231%-519% in a current range of 50–150mA, when compared to the base-CFRP. Also, the surface temperature of CNT webs decorated CFRP can be improved by 20.5–32.3℃ within 3min showing a self-heating rate of 6.8–10.8℃/min just with an applied voltage of 20–30V, increased by 152%-177% when compared to the base-CFRP(2.7–3.9℃/min). Also, deicing can be finished within 4–10min with a voltage of 18V and an input power of 246W/m^(2). Moreover, the electrothermal processes nearly have no negative effect on the mechanical properties of the CFRP. The relatively low input power and short response time for deicing make the CNT webs decorated CFRP may be a potential new generation for aeronautical deicing structure.

关键词： Composites Carbon Fiber Reinforced Plastics(CFRPs) Carbon nanotubes Electrical conductivity Electrothermal effect Deicing

Hydroelastic interaction between water waves and a thin elastic plate of arbitrary geometry

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Science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 59-66页

作者： xu feng LU DongQiang Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai 200072 China

An analytical method is developed for the hydroelastic interaction between surface incident waves and a thin elastic plate of arbitrary geometry floating on an inviscid fluid of finite depth in the framework of linear potential *** kinds of edge conditions are considered and the corresponding analytical representations are derived in the polar coordinate *** to the surface boundary conditions,the fluid domain is divided into two regions,namely,an open water region and a plate-covered *** the assumption that all the motion is time-harmonic,the series solutions for the spatial velocity potentials are derived by the method of eigenfunction *** matching conditions for the continuities of the velocity and pressure are transformed by taking the inner products successively with respect to the vertical eigenfunction for the free surface and the angular eigenfunction.A system of simultaneous equations,including two edge conditions and two matching conditions,is set up for deriving the expansion *** an example,numerical computation for the expansion coefficients of truncated series is performed for an elliptic *** results show that the method suggested here is useful to revealing the physical features of the gravity wave scattering in the open water and the hydroelastic response in the plate.

关键词： wave scattering method of matched eigenfunction expansions elastic plate arbitrary geometry hydroelastic response

Stress analysis of anisotropic thick laminates in cylindrical bending using a semi-analytical approach

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1740-1745页

作者： LU Chao-feng LIM C.W. xu feng Department of Civil Engineering Zhejiang University Hangzhou 310027 China） Department of Building and Construction City University of Hong Kong Kowloon Hong Kong China Zhejiang Tiandi Environmental Protection Engineering Co. Ltd. Hangzhou 310012 China

Semi-analytical elasticity solutions for bending of angle-ply laminates in cylindrical bending are presented using the state-space-based differential quadrature method (SSDQM). Partial differential state equation is derived from the basic equations of elasticity based on the state space concept. Then, the differential quadrature (DQ) technique is introduced to discretize the longitu- dinal domain of the plate so that a series of ordinary differential state equations are obtained at the discrete points. Meanwhile, the edge constrained conditions are handled directly using the stress and displacement components without the Saint-Venant principle. The thickness domain is solved analytically based on the state space formalism along with the continuity conditions at interfaces. The present method is validated by comparing the results to the exact solutions of Pagano’s problem. Numerical results for fully clamped thick laminates are presented, and the influences of ply angle on stress distributions are discussed.

关键词： Semi-analytical elasticity solution State-space-based differential quadrature method (SSDQM) Angle-ply laminates Cylindrical bending

Soft Fibrous Structures in Nature as Liquid Catcher

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Acta Mechanica Solida Sinica 2019年第5期32卷 580-590页

作者： Moxiao Li Tianjian Lu feng xu State Key Laboratory for Strength and Vibration of Mechanical Structures School of AerospaceXi'an Jiaotong UniversityXi'an 710049China Bioinspired Engineering and Biomechanics Center(BEBC) Xi'an Jiaotong UniversityXi'an 710049China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Nanjing Center for Multifunctional Lightweight Materials and Structures(MLMS) Nanjing University of Aeronautics and AstronauticsNanjing 210016China The Key Laboratory of Biomedical Information Engineering of the Ministry of Education School of Life Science and TechnologyXi'an Jiaotong UniversityXi'an 710049China

Past decades have witnessed the explosive growth of interest in the field of bioinspired materials,of which the structures and properties can be well utilized for industrial and bioengineering *** these structures,the natural fibrous structures propose diverse strategies to adapt to their environment,offering inspirations for versatile applications,especially droplet *** various well-adapted soft structures and materials,these fibrous structures show good control over their interaction with liquids(e.g.,water),providing a database full of effective solutions to these droplet-related scientific and technical problems(e.g.,colloidal synthesis,single-cell gene sequencing,drug delivery and solution synthesis).In this review,the current achievements in water collection by multiple fibrous structures are highlighted;the structures,basic models,bio-inspired structures and their applications are presented;and the current challenges and future prospects for the development of bio-inspired fibrous structures are discussed.

关键词： Soft fibrous structure Micro-and nanostructure Bio-inspired materials Surface tension

Dynamic interaction analysis and pairing evaluation in control configuration design

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Chinese Journal of Chemical Engineering 2016年第7期24卷 861-868页

作者： Xionglin Luo Pengfei Cao feng xu Department of Automation China University of PetroleumBeijing

This paper presents some new dynamic interaction analysis approaches for square or non-square systems and a pairing evaluation method. For square stable systems, an open-loop approach is proposed, which features the tradeoff between the contributions of response time constant and delay time to relative gain. For non-square stable systems, an extension from the proposed open-loop approach for square systems is presented and the corresponding pairing procedure is given. No interaction analysis approach is perfect for all systems, so any recommended pairing needs to be examined. An evaluation method is proposed in closed-loop with optimal controllers for each loop and whether the pairing is appropriate can be evaluated through testing if the equivalent relative gain is within defined scope. The advantages and effectiveness of proposed interaction analysis approaches and pairing evaluation method are highlighted via several examples of industrial processes.

关键词： Control configurationInteractionPairing evaluationNon-square systemsPID

Temporal and Tissue-Specific Expression of Tomato 14-3-3 Gene Family in Response to Phosphorus Deficiency

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Pedosphere 2012年第6期22卷 735-745页

作者： xu Wei-feng SHI Wei-Ming YAN feng State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) Institute of Crop Science and Plant Breeding Justus-Liebig UniversityLudwigstrasse 2335390 Giessen(Germany)

Plants adapt to phosphorus （P） deficiency through a complex of biological processes and many genes are involved. Tomato （Solanum lycopersicum L. ＇Hezuo906＇） plants were selected to grown hydroponically to study the temporal and spatial gene expression patterns of the 14-3-3 gene family and their roles in response to P deficiency in tomato plants. Using real-time reverse-transcriptase polymerase chain reaction （RT-PCR）, we investigated the expression profiles in different tissues （root, stem and leaf） at short-term and long-term P-deficient stress phases. Results revealed that i） four members of 14-3-3 gene family （TFT1, TFT4, TFT6 and TFTT） were involved in the adaptation of tomato plants to P deficiency, ii） TFT7 responded quickly to P deficiency in the root, while TFT6 responded slowly to P deficiency in the leaf, iii） expression response of TFT4 to P-deficient stress was widely distributed in different tissues （root, stem and leaf） while TFT8 only displayed stem-specific expression, and iv） temporal and tissues-specific expression patterns to P deficiency suggested that isoform specificity existed in tomato 14-3-3 gene family. We propose that TFT7 （one member of e-like group in tomato 14-3-3 family） is the early responsive gene and may play a role in the adaptation of tomato plants to shortterm P deficiency, while TFT6 （one member of non-e group in tomato 14-3-3 family） is the later responsive gene and may play a role in the adaptation of tomato plants to long-term P deficiency.

关键词： isoform specificity mRNA P starvation primer pairs real-time RT-PCR

Phase transformation at controlled locations in nanowires by in situ electron irradiation

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Nano Research 2020年第7期13卷 1912-1919页

作者： Hongtao Zhang Wen Wang Tao xu feng xu Litao Sun SEU-FEI Nano-Pico Center Key Laboratory ofMEMS of Ministry of EducationSoutheast UniversityNanjing 210096China Center for Advanced Materials and Manufacture Southeast University-Monash University Joint Research InstituteSuzhou 215123China

Solid state phase transtormations have drawn great attention because they can be effectively exploited to control the microstructure and property of *** the physics of such phase transformation processes is critical to designing materials with controlled structure and with desired ***,in traditional ex situ experiments,it is hard to achieve position controlled phase transformations or obtain desirable crystal phase on nanometer *** the underlying mechanisms of the reaction processes are not fully understood due to the lack of direct and real-time *** this paper,we observe phase transformation from body-centered tetragonal PX PbTiO3 to monclinic TiO2(B)on the atomic scale by in situ electron iradiation during heat treatment in transmission electron microscope,at pre-defined locations on the *** demonstrate that by controlling the location of the incident electron beam,a porous TiO2(B)crystal structure can be formed at the desired area on the nanowire,which is dificult to achieve by traditional synthesis *** in situ heating,the Pb atoms in the crystal migrate out of the pristine nanowire through inelastic scattering under incident electrons while high temperature(>400℃)provides energy for the crytalization of TiO2(B)and the vlatlization of a substantial number of Pb atoms,which makes the resultingTiO2(B)nanowires to be *** contrast,at temperatures<400℃,the segregated Pb atoms form Pb particles and the TiO、nanowires remain in the amorphous *** work not only provides in situ visualization of the phase transition from the PX-PbTiO3 to monoclinic TiO2(B),but also suggests a crystallography engineering strategy to obtain the desired crystal phase at controlled locations on the nanometer scale.

关键词： phase transformation controlled locations in situ transmission electron microscopy

Reciprocal translation between SAR and optical remote sensing images with cascaded-residual adversarial networks

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Science China(Information Sciences) 2021年第2期64卷 154-168页

作者： Shilei FU feng xu Ya-Qiu JIN Key Lab for Information Science of Electromagnetic Waves (MoE) Fudan University

Despite the advantages of all-weather and all-day high-resolution imaging, synthetic aperture radar(SAR) images are much less viewed and used by general people because human vision is not adapted to microwave scattering phenomenon. However, expert interpreters can be trained by comparing side-byside SAR and optical images to learn the mapping rules from SAR to optical. This paper attempts to develop machine intelligence that is trainable with large-volume co-registered SAR and optical images to translate SAR images to optical version for assisted SAR image interpretation. Reciprocal SAR-optical image translation is a challenging task because it is a raw data translation between two physically very different sensing modalities. Inspired by recent progresses in image translation studies in computer vision,this paper tackles the problem of SAR-optical reciprocal translation with an adversarial network scheme where cascaded residual connections and hybrid L1-GAN loss are employed. It is trained and tested on both spaceborne Gaofen-3(GF-3) and airborne Uninhabited Airborne Vehicle Synthetic Aperture Radar(UAVSAR) images. Results are presented for datasets of different resolutions and polarizations and compared with other state-of-the-art methods. The Frechet inception distance(FID) is used to quantitatively evaluate the translation performance. The possibility of unsupervised learning with unpaired/unregistered SAR and optical images is also explored. Results show that the proposed translation network works well under many scenarios and it could potentially be used for assisted SAR interpretation.

关键词： synthetic aperture radar generative adversarial network (GAN) image translation cascaded residual connection Frechet inception distance

The Impact of Competition on Analysts’Forecasts:A Simple Agent-Based Model

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Journal of Systems Science & Complexity 2020年第6期33卷 1980-1996页

作者： ZHANG Jin XIONG Xiong AN Yahui feng xu College of Management and Economics Tianjin UniversityTianjin 300072China School of Economics Tianjin University of CommerceTianjin 300134China College of Management and Econonics Tianjin UniversityTianjin 300072China

This paper builds an agent-based model to study the impact of analyst competition on analyst *** strategies(a catering strategy and a pressure strategy)are used to model analysts conflicts of interest between listed corporations and institutional *** finding suggests that the relationship between competition and analyst optimism is ***-level competition generates more analyst unbiased ***,the condition of no competition or high-level competition generates more analyst optimistic *** empirical test also confirms that analysts issue less biased earnings forecasts under the condition of low-level competition.

关键词： Agent-based model analyst forecasts conflicts of interest