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Effects of Gap Width and Groove on the Mechanical Properties of Butt Joint Between Aluminum Alloy and Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 143-148页

作者： Honggang DONG Chuanqing liao School of Materials Science and Engineering Dalian University of Technology Shanghai Aerospace Equipments manufacturer

Butt joining of 5A02 aluminum alloy to 304 stainless steel sheets was conducted using gas tungsten arc welding process with Al-12%Si （wt.%, the same below） and Zn-15%Al flux-cored filler wires. The effects of gap width and groove in steel side on the microstructure and tensile strength of the resultant joints were investigated. For the joint made with 0 mm-wide gap and without groove in steel side, severe incomplete brazing zone occurred along the steel side and bottom surfaces, and consequently seriously deteriorated the joint strength. However, presetting 1.5 mm-wide gap or with groove in steel side could promote the wetting of molten filler metal on the laying surfaces, and then significantly enhance the resultant joint strength. Moreover, post-weld heat treatment could further improve the tensile strength of the joints. During tensile testing, the specimens from the joints made with AI-12%Si flux-cored filler wire fractured through the weld or interracial layer, but those from the heat-treated joints made with Zn-15%AI flux-cored filler wire fractured in the aluminum base metal.

关键词： Aluminum Stainless steel Arc-brazing Gap width Groove Mechanical property

Ribosomal proteins:functions beyond the ribosome

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Journal of Molecular Cell Biology 2015年第2期7卷 92-104页

作者： Xiang Zhou Wen-Juan liao Jun-Ming liao Peng liao Hua Lu Department of Biochemistry&Molecular Biology and Tulane Cancer Center Tulane University School of MedicineNew OrleansLA 70112USA

Although ribosomal proteins are known for playing an essential role in ribosome assembly and protein translation,their ribosomeindependent functions have also been greatly *** the past decade,more than a dozen of ribosomal proteins have been found to activate the tumor suppressor p53 pathway in response to ribosomal *** addition,these ribosomal proteins are involved in various physiological and pathological *** review is composed to overview the current understanding of how ribosomal stress provokes the accumulation of ribosome-free ribosomal proteins,as well as the ribosome-independent functions of ribosomal proteins in tumorigenesis,immune signaling,and *** propose the potential of applying these pieces of knowledge to the development of ribosomal stress-based cancer therapeutics.

关键词： ribosomal protein ribosomal stress p53 MDM2 cancer immunity ribosomopathy

More than six hundred new families of Newtonian periodic planar collisionless three-body orbits

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Science China(Physics,Mechanics & Astronomy) 2017年第12期60卷 63-69页

作者： XiaoMing Li ShiJun liao School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200240 China MoE Key Laboratory in Scientific and Engineering Computing Shanghai 200240 China

The famous three-body problem can be traced back to Isaac Newton in the 1680 s. In the 300 years since this "three-body problem"was first recognized, only three families of periodic solutions had been found, until 2013 when ˇSuvakov and Dmitraˇsinovi′c [***. Lett. 110, 114301(2013)] made a breakthrough to numerically find 13 new distinct periodic orbits, which belong to 11 new families of Newtonian planar three-body problem with equal mass and zero angular momentum. In this paper, we numerically obtain 695 families of Newtonian periodic planar collisionless orbits of three-body system with equal mass and zero angular momentum in case of initial conditions with isosceles collinear configuration, including the well-known figure-eight family found by Moore in 1993, the 11 families found by ˇSuvakov and Dmitraˇsinovi′c in 2013, and more than 600 new families that have never been reported, to the best of our knowledge. With the definition of the average period T = T=Lf, where Lf is the length of the so-called "free group element", these 695 families suggest that there should exist the quasi Kepler's third law T* ≈ 2:433 ± 0:075 for the considered case, where T*= T|E|^(3/2) is the scale-invariant average period and E is its total kinetic and potential energy,respectively. The movies of these 695 periodic orbits in the real space and the corresponding close curves on the "shape sphere"can be found via the website: http://***/three-body/***.

关键词： three-body problem periodic orbits clean numerical simulation(CNS)

An explicit method for numerical simulation of wave equations: 3D wave motion

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Earthquake Engineering and Engineering Vibration 2011年第1期10卷 13-20页

作者： Liu Heng liao Zhenpeng Department of Civil Engineering Tsinghua University Beijing 100084 China Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China Department of Shipbuilding and Ocean Engineering Harbin Engineering University Harbin 150001 China

In this paper, an explicit method is generalized from 1D and 2D models to a 3D model for numerical simulation of wave motion, and the corresponding recursion formulas are developed for 3D irregular grids. For uniform cubic grids, the approach used to establish stable formulas with 2M-order accuracy is discussed in detail, with M being a positive integer, and is illustrated by establishing second order （M=1） recursion formulas. The theoretical results presented in this paper are demonstrated through numerical testing.

关键词： 3D wave equation numerical simulation explicit recursion formula finite element method

Effect of Surface Topography on Stress Concentration Factor

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1141-1148页

作者： CHENG Zhengkun liao Ridong School of Mechanical Engineering Beijing Institute of Technology

Neuber rule and Arola-Ramulu model are widely used to predict the stress concentration factor of rough specimens. However, the height parameters and effective valley radius used in these two models depend strongly on the resolution of the roughness-measuring instruments and are easily introduce measuring errors. Besides, it is difficult to find a suitable parameter to characterize surface topography to quantitatively describe its effect on stress concentration factor. In order to overcome these disadvantages, profile moments are carried out to characterize surface topography, surface topography is simulated by superposing series of cosine components, the stress concentration factors of different micro cosine-shaped surface topographies are investigated by finite element analysis. In terms of micro cosine-shaped surface topography, an equation using the second profile moment to estimate the stress concentration factor is proposed, predictions for the stress concentration factor using the proposed expression are within 10% error compared with the results of finite element analysis, which are more accurate than other models. Moreover, the proposed equation is applied to the real surface topography machined by turning. Predictions for the stress concentration factor using the proposed expression are within 10% of the maximum stress concentration factors and about 5% of the effective stress concentration factors estimated from the finite element analysis for three levels of turning surface topographies under different simulated scales. The proposed model is feasible in predicting the stress concentration factors of real machined surface topographies.

关键词： surface topography profile moments stress concentration factor finite element method

Optimal Fixed-Point Tracking Control for Discrete-Time Nonlinear Systems via ADP

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IEEE/CAA Journal of Automatica Sinica 2019年第3期6卷 657-666页

作者： Ruizhuo Song liao Zhu IEEE the School of Automation and Electrical Engineering University of Science and Technology Beijing

Based on adaptive dynamic programming(ADP),the fixed-point tracking control problem is solved by a value iteration(VI) algorithm. First, a class of discrete-time(DT)nonlinear system with disturbance is considered. Second, the convergence of a VI algorithm is given. It is proven that the iterative cost function precisely converges to the optimal value,and the control input and disturbance input also converges to the optimal values. Third, a novel analysis pertaining to the range of the discount factor is presented, where the cost function serves as a Lyapunov function. Finally, neural networks(NNs) are employed to approximate the cost function, the control law, and the disturbance law. Simulation examples are given to illustrate the effective performance of the proposed method.

关键词： Adaptive dynamic programming (ADP) fixedpoint tracking optimal control

ON THE COMPLEXITY OF THE NORMAL BASES VIA PRIME GAUSS PERIOD OVER FINITE FIELDS

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Journal of Systems Science & Complexity 2009年第3期22卷 395-406页

作者： Qunying liao Keqin FENG College of Mathematics and Software Science Sichuan Normal University Chengdu 610066 China Departmentof Mathematical Sciences Tsinghua University Beijing 100084 China. Department of Mathematical Sciences Tsinghua University Beijing 100084 China.

A formula on the complexity of the normal bases generated by prime Gauss period overfinite fields is presented in terms of cyclotomic ***,the authors determine explicitly thecomplexity of such normal bases and their dual bases in several cases where the related cyclotomicnumbers have been ***,the authors find several series of such normal bases withlow complexity.

关键词： Complexity cyclotomic number finite field Gauss period normal basis.

Clean numerical simulation:a new strategy to obtain reliable solutions of chaotic dynamic systems

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Applied Mathematics and Mechanics(English Edition) 2018年第11期39卷 1529-1546页

作者： Xiaoming LI Shijun liao School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Ocean Engineering Shanghai 200240China Collaborative Innovative Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China Ministry-of-Education Key Laboratory of Scientific and Engineering Computing Shanghai 200240China

It is well-known that chaotic dynamic systems, e.g., three-body system and turbulent flow, have sensitive dependence on the initial conditions(SDIC). Unfortunately,numerical noises, i.e., truncation error and round-off error, always exist in practice. Thus,due to the SDIC, the long-term accurate prediction of chaotic dynamic systems is practically impossible. In this paper, a new strategy for chaotic dynamic systems, i.e., the clean numerical simulation(CNS), is briefly described, and applied to a few Hamiltonian chaotic systems. With negligible numerical noises, the CNS can provide convergent(reliable) chaotic trajectories in a long enough interval of time. This is very important for Hamiltonian systems, and thus should have many applications in various fields. It is found that the traditional numerical methods in double precision cannot give not only reliable trajectories but also reliable Fourier power spectra and autocorrelation functions(ACFs). In addition, even the statistic properties of chaotic systems cannot be correctly obtained by means of traditional numerical algorithms in double precision, as long as these statistics are time-dependent. The CNS results strongly suggest that one had better be very careful on the direct numerical simulation(DNS) results of statistically unsteady turbulent flows, although DNS results often agree well with experimental data when the turbulent flow is in a statistical stationary state.

关键词： chaos numerical noise clean numerical simulation(CNS) reliability of computation

Analytic approximations of Von Krmn plate under arbitrary uniform pressure—equations in integral form

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Science China(Physics,Mechanics & Astronomy) 2018年第1期61卷 57-67页

作者： XiaoXu Zhong ShiJun liao School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Collaborative Innovative Center for Advanced Ship and Deep-Sea Exploration State Key Laboratory of Ocean Engineering Ministry-of-Education Key Laboratory of Scientific and Engineering Computing

Analytic approximations of the Von Karman＇s plate equations in integral form for a circular plate under external uniform pressure to arbitrary magnitude are successfully obtained by means of the homotopy analysis method （HAM）, an analytic approximation technique for highly nonlinear problems. Two HAM-based approaches are proposed for either a given external uniform pressure Q or a given central deflection, respectively. Both of them are valid for uniform pressure to arbitrary magnitude by choosing proper values of the so-called convergence-control parameters c1 and c2 in the frame of the HAM. Besides, it is found that the HAM- based iteration approaches generally converge much faster than the interpolation iterative method. Furthermore, we prove that the interpolation iterative method is a special case of the first-order HAM iteration approach for a given external uniform pressure Q when c1= -0 and c2 = -1, where 0 denotes the interpolation iterative parameter. Therefore, according to the convergence theorem of Zheng and Zhou about the interpolation iterative method, the HAM-based approaches are valid for uniform pressure to arbitrary magnitude at least in the special case c1 = -0 and c2= -1. In addition, we prove that the HAM approach for the Von karman＇s plate equations in differential form is just a special case of the HAM for the Von karman＇s plate equations in integral form mentioned in this paper. All of these illustrate the validity and great potential of the HAM for highly nonlinear problems, and its superiority over perturbation techniques.

关键词： circular plate high nonlinearity homotopy analysis method