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Mobile Internet WebRTC and Related Technologies

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ZTE Communications 2014年第1期12卷 46-51页

作者： Zhenjiang Dong Congbing Li Wei Wang Da Lyu ZTE corporation

This paper describes an improved design for WebRTC technolo- gy. With this design, WebRTC communication at client side, server side, and between these two sides is improved. HTML5 WebSocket, media negotiation and synthesis, network address translator （NAT）/firewall traversal, Session Initiation Protocol （SIP） signaling interaction, and P2P communication security are all used in this improved design. This solution solves cross- browser running problem of WebRTC applications, reduces reli- ance on client-side processing capability, and reduces band- width consumption. With this design, WebRTC also become more scalable.

关键词： WebRTC technology application model running across brows-ers extension

Intelligent fault diagnosis methods toward gas turbine: A review

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Chinese Journal of Aeronautics 2024年第4期37卷 93-120页

作者： Xiaofeng LIU Yingjie CHEN Liuqi XIONG Jianhua WANG Chenshuang LUO Liming ZHANG Kehuan WANG School of Transportation Science and Engineering Beihang UniversityBeijing 100191China Systems Engineering Research Institute China State Shipbuilding CorporationBeijing 100094China

Fault diagnosis plays a significant role in conducting condition-based maintenance and health management for gas turbines(GTs) to improve reliability and reduce costs. Various diagnosis methods developed by modeling engine systems or certain components implement faults detection and diagnosis based on the measurement of systemic parameters deviations. However, these conventional model-based methods are hindered by limitations of inability to handle the nonlinear nature, measurement uncertainty, fault coupling and other implementing problems. Recently, the development of artificial intelligence algorithms has provided an effective solution to the above problems, triggering broad researches for data-driven fault diagnosis methods with better accuracy,dynamic performance, and universality. This paper presents a systematic review of recently proposed intelligent fault diagnosis methods for GT engines, according to the classification of shallow learning methods, deep learning methods and hybrid intelligent methods. Moreover, the principle of typical algorithms, the evolution of enhanced methods, and the assessment of pros and cons are summarized to conclude the present status and look forward to the future in the field of GT fault diagnosis. Possible directions for development in method validation, information fusion, and interpretability of intelligent diagnosis methods are concluded in the end to provide insightful concepts for scholars in related fields.

关键词： Fault diagnosis Health management Gas turbine Artificial intelligence Intelligent diagnosis method

Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy

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Journal of Rare Earths 2006年第Z2期24卷 397-400页

作者：于升学吕巧艳韩婧张占伟张倩云 Department of Applied Chemistry Yanshan University Special Process Factory of Inner Mongolia North Heavy Industries Group Limited CorporationBaotou 014033China

Golden yellow cerium conversion film was obtained on magnesium alloys surface by immersion method and the preparation parameters were established. The influence of different process parameters on the surface morphology and performance of the conversion film were analyzed by means of SEM and electrochemical method. Formation dynamics about cerium conversion film on magnesium alloy in solution containing cerium salt and the anti-corrosion behavior of the conversion film in 3.5% NaCl solution were studied by electrochemical method respectively. The results shows that the conversion film is more compact at room temperature when concentration of cerium sulfate is 10 g·L-1 in the solution; the open circuit potential of the magnesium sample moves up to positive direction about 100 mV, the surface of conversion film becomes even and lustrous, and the adhesion intensity of conversion film increases when adding aluminum nitrate into the solution containing cerium salt. The pH value of the solution and immersion time of the sample in the solution also affect the surface morphology and anti-corrosion property of the conversion film. After covered by rare earths conversion film, the anti-corrosion property of magnesium alloy is obviously improved. Rare earth conversion film has self-repairing capability in corrosion medium.

关键词： magnesium alloy chemical conversion film corrosion resistance rare earths

Theoretical calculation of the impact work in the alloying non-quenched and tempered steel

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Science China(Technological Sciences) 2006年第3期49卷 257-273页

作者： LIU Zhilin1, LIN Cheng1 & GUO Yanchang2 1. Department of Materials and Chemical Engineering, Liaoning Institute of Technology, Jinzhou 121001, China 2. The Technical Center of Benxi Iron and Steel Group corporation, Benxi 117000, China Department of Materials and Chemical Engineering Liaoning Institute of Technology Jinzhou China The Technical Center of Benxi Iron and Steel Group corporation Benxi China

Coupled with hot-continuous rolling technology and based on the calculation of the finishing rolling impact work in the non-quenched and tempered Si-Mn steel, the calculations of the finishing rolling impact work in the alloying non-quenched and tempered steel with the elements of Cr, Ni, Mo, W, Cu, V, Nb and Ti are studied with the covalent electron number nA of the strongest bond in alloying phases, the smallest electron density difference ?ρ of phase interfaces, and the number of atom states σ (σ′) which keep the interface electron density continuous. The calculated results show that the finishing rolling impact work of the alloying non-quenched and tempered steel intensely depends on strengthening mechanisms. The solution strengthening, interface strengthening, precipita- tion strengthening of pearlite, and dispersion strengthening will result in the decrease of the finishing rolling impact work; the refinement strengthening, the precipitation strength- ening of V, Nb and Ti in α-Fe-C-V(Nb, Ti), and the residual austenite containing Ni on the boundary of α-Fe-C-Ni will increase the impact work; and the increments or decrements can be calculated with nA, ?ρ, σ (σ′) and weights of alloying elements. The calculation formulas of the finishing rolling impact work in this paper are intergraded with the sug- gested ones of the finishing rolling tensile strength, yield strength, and elongation of the non-quenched and tempered steel. The calculated results agree well with the measured ones.

关键词： alloying non-quenched and tempered steel, electron structure, impact work, calculation.

Joint TDOA and AOA location algorithm

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Journal of Systems Engineering and Electronics 2013年第2期24卷 183-188页

作者： Congfeng Liu Jie Yang Fengshuai Wang Institute of Electronic Countermeasure Xidian University School of Communication and Information Xi'an University of Posts and Telecommunications The 54th Institute of China Electronics Technology Group corporation

For the joint time difference of arrival（TDOA） and angle of arrival（AOA） location scene,two methods are proposed based on the rectangular coordinates and the polar coordinates,*** problem is solved perfectly by calculating the target position with the joint TDOA and AOA *** the condition of rectangular coordinates,first of all,it figures out the radial range between target and reference stations,then calculates the location of the *** the case of polar coordinates,first of all,it figures out the azimuth between target and reference stations,then figures out the radial range between target and reference stations,finally obtains the location of the ***,simulation analyses show that the theoretical analysis is correct,and the proposed methods also provide the application of the joint TDOA and AOA location algorithm with the theoretical basis.

关键词： passive location joint time difference of arrival (TDOA)and angle of arrival (AOA) location direct solution method perfor-mance analysis.

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

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International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 518-524页

作者： Jing Wang Min-xu Lu Lei Zhang Wei Chang Li-ning Xu Li-hua Hu Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing 100083 China Research Institute of China National Offshore Oil corporation Beijing 100027 China

To obtain high-quality dissimilar weld joints, the processes of metal inert gas （MIG） welding and tungsten inert gas （TIG） welding for duplex stainless steel （DSS） and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy （SEM）; the chemical compositions in different zones were detected by en- ergy-dispersive spectroscopy （EDS）; the mechanical properties were measured by microhardness test, tensile test, and impact test; the corro- sion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG weld- ing. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaC1 solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints pro- duced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS $31803 duplex stainless steel and low alloy steel in practical application.

关键词： dissimilar metals welds stainless steel alloy steel microstructure mechanical properties corrosion

Assessment on critical technologies for conceptual design of blended-wing-body civil aircraft

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Chinese Journal of Aeronautics 2019年第8期32卷 1797-1827,1794页

作者： Zhenli CHEN Minghui ZHANG Yingchun CHEN Weimin SANG Zhaoguang TAN Dong LI Binqian ZHANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Shanghai Aircraft Design and Research Institute Commercial Aircraft Corporation of China LtdShanghai 201210China

Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing(TAW) configuration following the Cayley’s design principles has been optimized to the architecture’s limit, which can hardly satisfy the further requirements on green aviation. By past decades’ investigations the BlendedWing-Body(BWB) concept has emerged as a potential solution, which can simultaneously fulfill metrics of noise, emission and fuel burn. The purpose of the present work is to analyze the developments of critical technologies for BWB conceptual design from a historical perspective of technology progress. It was found that the high aerodynamic efficiency of BWB aircraft can be well scaled by the mean aerodynamic chord and wetted aspect ratio, and should be realized with the trade-offs among stability and control and low-speed performance. The structure concepts of non-cylinder pressurized cabin are of high risks on weight prediction and weight penalty. A static stability criterion is recommended and further clear and adequate criteria are required by the evaluations of flying and handling qualities. The difficulties of propulsion and airframe integration are analyzed. The energy to revenue work ratios of well-developed BWB configurations are compared,which are 31.5% and 40% better than that of TAW, using state-of-art engine technology and future engine technology, respectively. Finally, further study aspects are advocated.

关键词： Aerodynamic design Bended-wing-body Propulsion Airframe Integration Stability and control Structure

Influence of solution Composition on Formation of Golden Yellow Rare Earth Conversion Film on Magnesium Alloy

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Journal of Rare Earths 2005年第S1期23卷 255-258页

作者：于升学张占伟陈玲韩婧 Department of Applied Chemistry Yanshan University Qinhuangdao 066004 China Special Process Factory of Inner Mongolia North Heavy Industries Group Limited corporation Baotou 014033 ChinaDepartment of Applied Chemistry Yanshan University Qinhuangdao 066004 China Special Process Factory of Inner Mongolia North Heavy Industries Group Limited corporation Baotou 014033 China

Cerium sulfate was used as main composite in solution to prepare golden yellow chemical conversion film on magnesium alloy. The influence of solution composition on the surface morphology of golden yellow rare earth conversion film on magnesium alloy was studied by means of SEM; potential-time curves in the formation process of rare earth conversion film and the anti-corrosion property of the conversion film were tested through ECT. The results show that, when there is no other component in the solution besides cerium sulfate, yellow film can be obtained on magnesium alloy, but there are some dusts on the film surface and the solution is not stable. The stability of cerium sulfate solution increases with adding hydrogen peroxide, while the film is thin and its color turn light. After adding combination additive containing Al 3+, smooth and compact golden yellow film was obtained on magnesium alloy. The polarization curves tested in 3.5% NaCl solution show that the anti-corrosion property of magnesium alloy is increased obviously by rare earth conversion film, and the film has self-repairing capability in the corrosion process.

关键词： magnesium alloy chemical conversion film rare earths

Analytical study on the dynamic displacement response of a curved track subjected to moving loads

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 867-879页

作者： Ke-fei LI Wei-ning LIU Valeri MARKINE Zhi-wei HAN School of Civil Engineering Beijing Jiaotong University Beijing MTR Construction Administration corporation Railway Engineering Group Faculty of Civil Engineering and Geosciences Delft University of Technology

A closed-form out-of-plane dynamic displacement response of a curved track subjected to moving loads was *** track structure was modeled as a planar curved Timoshenko beam periodically supported by the double-layer spring-damping *** general dynamic displacement response induced by the moving loads along the curve on the elastic semi-infinite space was firstly obtained in the frequency domain,according to the Duhamel integral and the dynamic reciprocity *** the case of the periodic curved track structure subjected to moving loads,the dynamic displacement equation was simplified into a form of summation within the basic track cell instead of the *** transfer function for the curved track was expressed in the form of a transfer *** and series moving loads were involved in the calculation *** the verification of the analytical model,the mid-span vertical deflection of a simply support curved beam subjected to moving load was recalculated and compared with the same case in the *** research results indicate that:under the same moving loads,the displacement response of the curved track decreases slightly with the increasing track radius,and the displacement response of the curved track with the radius greater than or equal to 600 m is almost equivalent to the displacement response of the straight track;the frequency spectrum of the curved track is more abundant than that of the straight track,which may result in more wheel-rail resonance and rail corrugation in the curved lines.

关键词： Curved track Moving loads Dynamic displacement Analytical solution Transfer function