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Six-DOF trajectory optimization for reusable launch vehicles via Gauss pseudospectral method

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Journal of Systems Engineering and Electronics 2016年第2期27卷 434-441页

作者： Zhen Wang zhong Wu School of Instrumentation Science and Optoelectronics Engineering Beihang UniversityBeijing 100191China China Institute of Marine Technology&Economy Beijing 100081China

To be close to the practical flight process and increase the precision of optimal trajectory, a six-degree-offreedom（6-DOF） trajectory is optimized for the reusable launch vehicle（RLV） using the Gauss pseudospectral method（GPM）. Different from the traditional trajectory optimization problem which generally considers the RLV as a point mass, the coupling between translational dynamics and rotational dynamics is taken into account. An optimization problem is formulated to minimize a performance index subject to 6-DOF equations of motion, including translational and rotational dynamics. A two-step optimal strategy is then introduced to reduce the large calculations caused by multiple variables and convergence confinement in 6-DOF trajectory optimization. The simulation results demonstrate that the 6-DOF trajectory optimal strategy for RLV is feasible.

关键词： reusable launch vehicle(RLV) trajectory optimization Gauss pseudospectral method(GPM)

Stability of nonlinear feedback shift registers

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Science China(Information Sciences) 2016年第1期59卷 201-212页

作者： Jianghua zhong Dongdai LIN State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences Institute of Complexity Science Qingdao University

Convolutional codes have been widely used in many applications such as digital video, radio, and mobile communication. Nonlinear feedback shift registers(NFSRs) are the main building blocks in convolutional decoders. A decoding error may result in a succession of further decoding errors. However, a stable NFSR can limit such an error-propagation. This paper studies the stability of NFSRs using a Boolean network approach. A Boolean network is an autonomous system that evolves as an automaton through Boolean functions. An NFSR can be viewed as a Boolean network. Based on its Boolean network representation, some sufficient and necessary conditions are provided for globally(locally) stable NFSRs. To determine the global stability of an NFSR with its stage greater than 1, the Boolean network approach requires lower time complexity of computations than the exhaustive search and the Lyapunov’s direct method.

关键词： nonlinear feedback shift register stability Boolean function Boolean network semi-tensor product

ON THE MINIMAL NONNEGATIVE SOLUTION OFNONSYMMETRIC ALGEBRAIC RICCATI EQUATION

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Journal of Computational Mathematics 2005年第3期23卷 305-320页

作者： Xiao-xiaGuo zhong-zhiBai LSEC ICMSECAcademyofMathematicsandSystemSciencesChineseAcademyofSciencesBeijing100080China

We study perturbation bound and structured condition number about the minimal nonnegative solution of nonsymmetric algebraic Riccati equation, obtaining a sharp perturbation bound and an accurate condition number. By using the matrix sign function method we present a new method for finding the minimal nonnegative solution of this algebraic Riccati equation. Based on this new method, we show how to compute the desired M-matrix solution of the quadratic matrix equation X^2 - EX - F = 0 by connecting it with the nonsymmetric algebraic Riccati equation, where E is a diagonal matrix and F is an M-matrix.

关键词： Nonsymmetric algebraic Riccati equation Minimal nonnegative solution Ma-trix sign function Quadratic matrix equation

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

DISPERSION OF CYLINDRICAL PARTICLES IN TURBULENT FLOWS

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Journal of Hydrodynamics 2004年第1期16卷 1-6页

作者： GAOZhen-yu LINJian-zhong DepartmentofMechanics StateKeyLaboratoryofFluidPowerTransmissionandControlZhejiangUniversityHangzhou310027China

With consideration of the Stokes drag and virtual mass force, the equationsfor mean and fluctuating velocities in rotation and translation were given for rigid cylindricalparticles moving in a turbulent flow. Then the rotational and translational dispersion coefficientsof particle were derived. The relationships between the dispersion, coefficients and flow lengthscale as well as particle characteristic parameters were analyzed. The resulting dispersioncoefficients were proved to decrease as the particle length increases. The conclusions are helpfulfor the further research on the motion of cylindrical particles in turbulent flows.

关键词： cylindrical particles turbulence dispersion coefficient

Aggregation operators on intuitionistic trapezoidal fuzzy number and its application to multi-criteria decision making problems

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Journal of Systems Engineering and Electronics 2009年第2期20卷 321-326页

作者： Wang Jianqiang Zhang zhong School of Business Central South Univ. Changsha 410083 P. R. China

Intuitionistic trapezoidal fuzzy numbers and their operational laws are defined. Based on these operational laws, some aggregation operators, including intuitionistic trapezoidal fuzzy weighted arithmetic averaging operator and weighted geometric averaging operator are proposed. Expected values, score function, and accuracy function of intuitionitsic trapezoidal fuzzy numbers are defined. Based on these, a kind of intuitionistic trapezoidal fuzzy multi-criteria decision making method is proposed. By using these aggregation operators, criteria values are aggregated and integrated intuitionistic trapezoidal fuzzy numbers of alternatives are attained. By comparing score function and accuracy function values of integrated fuzzy numbers, a ranking of the whole alternative set can be attained. An example is given to show the feasibility and availability of the method.

关键词： intuitionistic trapezoidal fuzzy numbers aggregation operators multi-criteria decision making

Constrained Hamilton variational principle for shallow water problems and Zu-class symplectic algorithm

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Applied Mathematics and Mechanics(English Edition) 2016年第1期37卷 1-14页

作者： Feng WU Wanxie zhong State Key Laboratory of Structural Analysis of Industrial Equipment Faculty of Vehicle Engineering and Mechanics Dalian University of Technology

In this paper, the shallow water problem is discussed. By treating the incompressible condition as the constraint, a constrained Hamilton variational principle is presented for the shallow water problem. Based on the constrained Hamilton variational principle, a shallow water equation based on displacement and pressure （SWE-DP） is developed. A hybrid numerical method combining the finite element method for spa- tial discretization and the Zu-class method for time integration is created for the SWE- DP. The correctness of the proposed SWE-DP is verified by numerical comparisons with two existing shallow water equations （SWEs）. The effectiveness of the hybrid numerical method proposed for the SWE-DP is also verified by numerical experiments. Moreover, the numerical experiments demonstrate that the Zu-class method shows excellent perfor- mance with respect to simulating the long time evolution of the shallow water.

关键词： shallow water equation (SWE) constrained Hamilton variational principle,Zu-class method

Chandra Observation of Point Sources in the X-Ray Elliptical Galaxy NGC 1407

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Chinese Journal of Astronomy and Astrophysics 2004年第3期4卷 221-230页

作者： zhong-LiZhang Hai-GuangXu NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012 DepartmentofPhysics ShanghaiJiaoTongUniversityShanghai200030

With the Chandra pointing observation of about 50 ks, we have detected 41 point sources in the X-ray relatively faint elliptical galaxy NGC 1407, most of which appear to be low mass X-ray binaries. In luminosity flux units, these resolved point sources contribute about 17.8 % of the total emission of the galaxy in 0.3–10 keV. Of the remaining diffuse emission, about 53.4 % (or 43.9 % of total) may arise from unresolved point sources. We find six ultraluminous X-ray sources with luminosities above 1039 erg s?1. This number is less than has been found in NGC 720, but more than in NGC 4697 and NGC 1553, so suggesting a possible correlation between the number of ULXs and the total X-ray luminosity of early-type galaxies. A central point-like source is detected whose luminosity (2.36 ± 0.14×1039 erg s?1) is the highest among all resolved sources. However, because of its relatively low hardness ratio, we speculate that it is not likely to be a low luminosity AGN.

关键词： binaries: close galaxies: elliptical and lenticular galaxies: individual:NGC 1407 X-rays: binaries X-rays: galaxies

Ultrasound-responsive Homopolymer Nanoparticles

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Chinese Journal of Polymer Science 2020年第4期38卷 349-356,I0006页

作者： Bo Yang Jian-zhong Du Department of Orthopedics Shanghai Tenth People's HospitalTongji University School of MedicineShanghai 200072China Department of Polymeric Materials School of Materials Science and EngineeringKey Laboratory of Advanced Civil Engineering Materials of Ministry of EducationTongji UniversityShanghai201804China

Nonin vasive ultraso und is a more effective strategy for on-demand drug delivery of polymeric nano particles than many other ***,the preparation of ultrasound-responsive homopolymer nanoparticles is still very *** this study,we disclose the regulating factors of ultrasound responsiveness of homopolymer nanoparticles and the disaggregation behavior of homopolymer nanoparticle *** nanoparticles such as vesicles and large compound micelles(LCMs)are self-assembled from poly(methoxyethyl methacrylate)(PMEMA)and poly(amic acid)(PAA),*** ultrasound responsiveness of PAA vesicles at metastable state could be regulated by tuning the self-assembly temperature(7^),and was optimized when Ts is around the glass transition temperature(7g)of ***,the PMEMA LCMs did not respond to ultrasound as they are at stable *** the other hand,poly(2-(2-ethoxyethoxy)ethyl acrylate)(PEEA)could self-assemble into vesicle aggregates or complex micelle aggregates,which were dissociated upon ***,the above findings provide us with a fresh in sight for designing ultrasound-responsive polymeric nanoparticles.

关键词： Ultrasound responsiveness Homopolymers Vesicles Micelles Self-assembly