摘要：The nonlinear governing equations of the liquid sloshing modals in a cylindrical storage tank are established. Through analytical analysis, the analytical expressions of the solutions of this kind of system are obtained. With different parameters, the dynamical behaviors of the solutions are different from the trivial ones. To prevent system instability, two selection principles that the stiffness equations are positive-definite and the nonlinear terms of the system are not regenerative elements are given. Meanwhile, numerical simulations are also given, which confirm the analytical results.

摘要：As a promising technique, surrogate-based design and optimization（SBDO） has been widely used in modern engineering design optimizations. Currently, static surrogate-based optimization methods have been successfully applied to expensive optimization problems. However, due to the low efficiency and poor flexibility, static surrogate-based optimization methods are difficult to efficiently solve practical engineering cases. At the aim of enhancing efficiency, a novel surrogate-based efficient optimization method is developed by using sequential radial basis function（SEO-SRBF）. Moreover, augmented Lagrangian multiplier method is adopted to solve the problems involving expensive constraints. In order to study the performance of SEO-SRBF, several numerical benchmark functions and engineering problems are solved by SEO-SRBF and other well-known surrogate-based optimization methods including EGO, MPS, and IARSM. The optimal solutions, number of function evaluations, and algorithm execution time are recorded for comparison. The comparison results demonstrate that SEO-SRBF shows satisfactory performance in both optimization efficiency and global convergence capability. The CPU time required for running SEO-SRBF is dramatically less than that of other algorithms. In the torque arm optimization case using FEA simulation, SEO-SRBF further reduces 21% of thematerial volume compared with the solution from static-RBF subject to the stress constraint. This study provides the efficient strategy to solve expensive constrained optimization problems.

摘要：Asteroid exploration trajectories which start from a lunar orbit are investigated in this *** is assumed that the probe departs from lunar orbit and returns to the vicinity of Earth,then escapes from the Earth by performing a perigee maneuver.A low-energy transfer in Sun-EarthMoon system is ***,the feasible region of lowenergy transfer from lunar orbit to perigee within 5 000 km height above the Earth surface in Sun-Earth-Moon system is calculated and *** transfer types are found,i.e.,large maneuver and fast transfers,small maneuver and fast transfers,and disordered and slow *** of feasibility trajectories belong to the first two ***,the lowenergy trajectory leg from lunar orbit to perigee and a heliocentric trajectory leg from perigee to asteroid are patched by a perigee *** optimal full-transfer trajectory is obtained by exploiting the differential evolution ***,taking 4179 Toutatis asteroid as the target,some low-energy transfer trajectories are obtained and analyzed.

摘要：High fidelity analysis are utilized in modern engineering design optimization problems which involve expensive black-box *** computation-intensive engineering design problems,efficient global optimization methods must be developed to relieve the computational burden.A new metamodel-based global optimization method using fuzzy clustering for design space reduction(MGO-FCR) is *** uniformly distributed initial sample points are generated by Latin hypercube design to construct the radial basis function metamodel,whose accuracy is improved with increasing number of sample points *** c-mean method and Gath-Geva clustering method are applied to divide the design space into several small interesting cluster spaces for low and high dimensional problems *** efficiency and accuracy are directly related to the design space,so unconcerned spaces are eliminated by the proposed reduction principle and two pseudo reduction *** reduction principle is developed to determine whether the current design space should be reduced and which space is *** first pseudo reduction algorithm improves the speed of clustering,while the second pseudo reduction algorithm ensures the design space to be *** several numerical benchmark functions,comparative studies with adaptive response surface method,approximated unimodal region elimination method and mode-pursuing sampling are carried *** optimization results reveal that this method captures the real global optimum for all the numerical benchmark *** the number of function evaluations show that the efficiency of this method is favorable especially for high dimensional *** on this global design optimization method,a design optimization of a lifting surface in high speed flow is carried out and this method saves about 10 h compared with genetic *** method possesses favorable performance on efficiency,robustness and capability of global

摘要：This paper focuses mainly on semi-strapdown image homing guided （SSIHG） system design based on optical flow for a six-degree-of-freedom （6-DOF） axial-symmetric skid-to-turn missile. Three optical flow algorithms suitable for large displacements are introduced and compared. The influence of different displacements on computational accuracy of the three algorithms is analyzed statistically. The total optical flow of the SSIHG missile is obtained using the Scale Invariant Feature Transform （SIFT） algorithm, which is the best among the three for large displacements. After removing the rotational optical flow caused by rotation of the gimbal and missile body from the total optical flow, the remaining translational optical flow is smoothed via Kalman filtering. The circular navigation guidance （CNG） law with impact angle constraint is then obtained utilizing the smoothed translational optical flow and position of the target image. Simulations are carried out under both disturbed and undisturbed conditions, and results indicate the proposed guidance strategy for SSIHG missiles can result in a precise target hit with a desired impact angle without the need for the time-to-go parameter.

摘要：We describe a system for turning the accumulator electric locomotives used in coal mines. This improves transport efficiency and decreases mine construction and production costs. The operating requirements, principles, working features and transmission system are discussed. This system has a simple structure and can be manufactured, transported and assembled easily. It, therefore, can handle accumulator locomotives of middle and small size.

摘要：This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP(circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3 BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE(differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations.

摘要：In this study,we propose valley phononic crystals that consist of a hexagonal aluminum plate with six chiral arrangements of *** phononic crystals were introduced into a topological insulator(TI)system to produce topologically protected edge waves(TPEW s)along the topological *** implementation of chiral topological edge states is different from the implementation of topological edge states of systems with *** the conventional breaking of mirror symmetry,a new complete band with topological edge modes gap was opened up at the Dirac point by tuning the difference in lengths of the ligaments in the chiral unit *** investigated the dispersion properties in chiral systems and applied the dispersion properties to waveguides on the interfaces to achieve designable route ***,we simulated the robust propagation of TPEWs in different routes and demonstrated their immunity to backscattering at ***,the existence of the valley Hall effect in chiral systems was *** study findings may lead to the further study of the topological states of chiral materials.

摘要：Inflatable space structures may undergo the vibration of a long duration because of their features of dynamic deployment,high flexibility,and low-frequency *** this paper,a topology optimization methodology is proposed to reduce the vibration of a spinning inflatable *** the first step,a variable-length shell element is developed in the framework of arbitrary Lagrange-Euler(ALE)and absolute nodal coordinate formulation(ANCF)to accurately model the deployment dynamics of the inflatable *** the help of two additional material coordinates,the shell element of ALE-ANCF has the ability to describe the large deformation,large overall motion,and variable length of an inflatable *** nonlinear elastic forces and additional inertial forces induced by the variable length are analytically *** the second step,a topology optimization procedure is presented for the dynamic response of an inflatable structure through the integration of the equivalent static loads(ESL)method and the density *** ESL sets of the variable-length inflatable structure are defined to simplify the dynamic topology optimization into a static one,while the density-based topology optimization method is used to describe the topology of the inflatable structure made of two materials and solve the static optimization *** order to obtain more robust optimization results,sensitivity analysis,density filter,and projection techniques are also ***,a benchmark example is presented to validate the ALE-ANCF modeling *** deployment dynamics and corresponding topology optimization of a spinning inflatable structure are studied to show the effectiveness of the proposed topology optimization methodology.

摘要：结构拓扑优化在过去的三十年里经历了巨大的发展,充分利用高性能计算资源有助于拓宽拓扑优化在大规模设计问题中的应用。本文提出了一种针对一般三维拓扑优化的基于子区域的并行策略。通过子区域划分、矩阵运算、引入单元硬杀算法,优化过程得以显著提速.将该策略整合进高效、简洁的Python代码;该代码可适用于任意形状的设计域.附录一中给出的完整代码,易于扩展,扩展后可解决多类优化问题.通过求解四个柔度最小化问题展示了该策略的高效性.本研究在机械工程、先进制造,以及建筑设计等领域有潜在的应用价值.