变可信度模型在气动优化中的应用

在气动外形优化中, 采用近似模型管理结构（AMF）方法,对变可信度模型进行组织和管理．这样能够充分利用低可信度模型,将主要计算量集中在低可信度模型的优化迭代过程中．同时,采用高可信度模型监控优化过程,使最终的优化解收敛到高可信度模型上．最后,设计了零阶变可信度气动特性优化管理结构与搜索算法,对某飞翼型无人机的翼型进行了气动优化．优化外形的气动性能与初始外形比有所提高．实际结果表明所提出的方法具有良好的可行性和适用性．     

From Inviscid to Viscous Aerodynamical Global Optimal Shape's Design

The refinement of the global aerodynamical optimal design (OD) of the shape of a flying configuration (FC) can be performed by improving of the start solutions for the optimization and/or of the optimization strategy itself. The proposed strategy is the own developed iterative optimum–optimorum theory. The study is here focused on the further improvement of her new, original, reinforced, zonal, spectral solutions for the partial–differential equations (PDEs) of the three–dimensional compressible Navier–Stokes layer (NSL), which govern the flow over the FCs, in subsonic and supersonic flow. These NSL's solutions, which are good suited for the computation and, especially, for the global optimal design, use the analytical potential solutions of the flow over the same FC twice: firstly as outer flow, at the NSL's edge (instead of the parallel flow used by Prandtl in his boundary layer theory) and, secondly, the velocity's components are products between the corresponding potential velocities and polynomial expansions with arbitrary coefficients, which are used to satisfy the NSL's PDEs. The use of analytical elliptical potential solutions leads to subsonic and the use of hyperbolical potential solutions leads to supersonic stabilized and rapid convergent NSL's solutions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stratospheric flights over tropical latitudes with polyethylene balloons of large volume

Balloons, upto two million cubic feet in volume, made out of locally extruded polyethylene film ·0011 inches thick, have been successfully flown and altitudes of upto 120,000 ft. attained. Instrumented pay-loads upto 100 kg. in weight have been floated at level ceilings around these altitudes. Various aspects, (such as balloon material, shape and design, and launching methods), which relate to the technique of flying polyethylene balloons of large volume over tropical latitudes are briefly discussed.     

Morphing of Flying Configuration Using Spanwise Movable Leading Edge Flaps,in Supersonic Flow

The computation of the flow over flattened wing-fuselage flying configuration (FC) with movable leading edge flaps in spanwise direction is here considered. Hyperbolical potential solutions are given in closed form and are used for the determination of hybrid solutions for the Navier-Stokes layer, over this FC with the flaps in retracted and in open position. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Driving while intoxicated (DWI) convictions and job-related flying performance—a study of commercial air safety

This paper is a report on the relationship between driving while intoxicated (DWI) convictions and job-related flying performance. The data, obtained by the Federal Aviation Administration, focuses on commercial air accidents and incidents in the years 1986–1992. Pilot-error accidents were modelled using logistic regression with age, experience (total flying hours), risk exposure (recent flying hours) and employer (major/non-major) as the independent variables. This study provides empirical evidence that job-related flying performance differs significantly between airline pilots with and without DWI convictions. It also suggests that passengers on a commercial flight flown by a pilot with DWI(s) may incur an increased accident risk. DWI background checks may be an effective method for improving commercial air safety if used with appropriate follow-up actions.     

An iterative optimum-optimorum theory for the design of a globally optimal shape

In some previous papers, the author has developed the optimum-optimorum theory, which solves an enlarged variational problem with free boundaries, inside of a class of flying configurations (FCs), defined by some chosen common properties. This optimization strategy was used by the author for the inviscid, aerodynamical, global optimal design of three models, namely, Adela, a delta wing alone and of two fully-integrated wing-fuselage FCs, namely, Fadet I and Fadet II, which have all high values of L/D (lift to drag). A further enlargement of the optimization strategy is developed here, in form of an iterative optimum-optimorum theory, which uses the inviscid global optimized FC's shape as first step of iteration and the own developed reinforced Navier-Stokes solutions up the first computational checking and up the second step of iteration. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Global Optimization of the Shape of a Suborbital Space Vehicle

The determination of the global optimized (GO) shapes of flying configurations leads to extended variational problems with free boundaries. The author has developed special optimization strategies called optimum optimorum and iterative optimum optimorum strategies and have used them for the design of GO shapes of three models, which are of minimum drag at three different supersonic cruising Mach numbers. These optimization strategies can be used for the determination of new GO shapes of more performant supersonic transport aircraft and space vehicles. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

New Zonal,Spectral Solutions for the Navier‐Stokes Layer and Their Applications

New zonal, spectral forms for the axial, lateral and vertical velocity's components, density function and absolute temperature inside of compressible three‐dimensional Navier‐Stokes layer (NSL) over flattened, flying configurations (FC), are here proposed. The inviscid flow over the FC, obtained after the solidification of the NSL, is here used as outer flow. If the spectral forms of the velocity's components are introduced in the partial differential equations of the NSL and the collocation method is used, the spectral coefficients are obtained by the iterative solving of an equivalent quadratical algebraic system with slightly variable coefficients.     

Hybrid,numerical solutions,for three-dimensional,compressible Navier-Stokes layer

The author proposes new hybrid solutions for the three-dimensional, compressible Navier-Stokes layer (NSL) over a flying configuration (FC), which use the analytical potential solutions, of the same FC, two times, namely: to reinforce the numerical solutions by multiplying them with these analytical solutions and as outer flow (instead of the parallel flow, used by Prandtl in his boundary layer theory). These hybrid solutions fulfill the last behavior, have correct jumps along the singular lines (like subsonic leading edges, junction lines wing-fuselage, etc.), are split, accurate and rapid convergent. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Focus characteristics of long distance flying optics

The ABCD law for the complex parameterq of the TEM₀₀, Gaussian beam is generally not valid for high-order modes. It can be used for the high-order modes or their superposition when the spot sizew in the virtual part of the parameterq is substituted by the Rayleigh rangeZ _R, of a certain resonator. The focus characteristics of long distance flying optics are studied in this paper theoretically and experimentally for the TEM _mn Gaussian beams between the two types of resonators without and with distortion. It is very important for the applications of the flying optical processing, the laser space craft and the spatial filter in the large laser project.     

The complexity of minimizing the number of shape matrices subject to minimal beam-on time in multileaf collimator field decomposition with bounded fluence

The use of multileaf collimators (MLCs) is a modern way to realize intensity modulated fields in radiotherapy. An important step in the treatment planning is the shape matrix decomposition: the desired fluence distribution, given by an integer matrix, has to be decomposed into a small number shape matrices, i.e. (0,1)-matrices corresponding to the field shapes that can be delivered by the MLC used. The two main objectives are to minimize the total irradiation time, and the number of shape matrices. Assuming that the entries of the fluence matrix are bounded by a constant, we prove that a shape matrix decomposition with minimal number of shape matrices under the condition that the total irradiation time is minimal, can be determined in time polynomial in the matrix dimensions. The results of our algorithm are compared with Engel’s [K. Engel, A new algorithm for optimal multileaf collimator field segmentation, Discrete Appl. Math. 152 (1-3) (2005) 35-51.] heuristic for the reduction of the number of shape matrices.     

炸药爆炸作用下飞片的运动

刚性飞片在炸药爆炸作用下的一维抛掷问题,仅当爆炸气体多方指数等于三时可以求得解析解;一般情况下须利用计算机求出数值解本文利用了爆炸气体中反射冲击波的“弱”击波特性,使飞片运动和飞片后方流场之间相互耦合的复杂问题解耦而归结为求解常微分方程问题;然后用小参数摄动法求出多方指数接近于三的各种炸药驱动飞片问题的近似解析解,所得飞片终速和数值解符合很好;从而给出了用爆速和多方指数等两个炸药示性参量表出的估算飞片运动的良好近似公式.     

Analytical Solution for the Deformation of a Cylinder under Tidal Gravitational Forces

Quite a few future high precision space missions for testing Special and General Relativity will use optical resonators which are used for laser frequency stabilisation. These devices are used for carrying out tests of the isotropy of light and of the universality of the gravitational redshift. As the resonator frequency not only depends on the speed of light but also on the resonator length, the quality of these measurements is very sensitive to elastic deformations of the optical resonator itself. As a consequence, a detailed knowledge about the deformations of the cavity is necessary. In this note we derive for the first time an analytical solution for the problem of an elastic, isotropic, homogeneous free–flying cylinder in space under the influence of a tidal gravitational force. A detailed derivation can be found in [4]. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel bee swarm optimization algorithm for numerical function optimization

The optimization algorithms which are inspired from intelligent behavior of honey bees are among the most recently introduced population based techniques. In this paper, a novel algorithm called bee swarm optimization, or BSO, and its two extensions for improving its performance are presented. The BSO is a population based optimization technique which is inspired from foraging behavior of honey bees. The proposed approach provides different patterns which are used by the bees to adjust their flying trajectories. As the first extension, the BSO algorithm introduces different approaches such as repulsion factor and penalizing fitness (RP) to mitigate the stagnation problem. Second, to maintain efficiently the balance between exploration and exploitation, time-varying weights (TVW) are introduced into the BSO algorithm. The proposed algorithm (BSO) and its two extensions (BSO–RP and BSO–RPTVW) are compared with existing algorithms which are based on intelligent behavior of honey bees, on a set of well known numerical test functions. The experimental results show that the BSO algorithms are effective and robust; produce excellent results, and outperform other algorithms investigated in this consideration.     

Boundary element and finite element analysis for the efficient simulation of fluid-structure interaction and its application to mold filling processes

Metal casting and polymer molding are widely used for the economical shape processing of complex geometries. In these manufacturing processes, a liquid melt (metal, mineral or synthetic) is filled into a mold with a cavity of the desired shape. Cooling and solidification of the melt results in a product with almost the same shape as the cavity. Numerical simulations can be employed to increase the accuracy of the process. To this end, boundary element method for Stokes flow and a finite element formulation for liquid membranes are investigated in this work. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Reconstruction of Geophysical Layers with Shape Optimization and Level Set Methods

A shape optimization method is used to reconstruct the unknown shape of geophysical layers from boundary heat flux measurements by the use of adjoint fields and level sets. The identification of the shape of the geophysical layers by boundary heat flux measurements is necessary for the efficient use of geothermal energy. The method of speed is used to calculate the shape sensitivities, and the continuous adjoint approach is followed for the computation of the shape derivatives. The unknown shape is described with the help of the level set function; the advantage of the shape function is that no mesh movement or remeshing is necessary, but an additional Hamilton-Jacobi equation has to be solved. This equation is solved in an artificial time, where the velocity represents the movement in the direction of the normal vector of the interface. For large optimization steps, re-initialization of the level set function is also necessary, in order to keep the magnitude of the level set function near unity and also to smooth the level set function. Numerical results are given for measured heat fluxes on the boundary of the domain for different time steps and conductivity ratios. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dynamic model of a flying manipulator with two highly flexible links

Nonlinear dynamic model of a flying manipulator with two revolute joints and two highly flexible links is obtained using Hamilton’s principle. Flying base of the manipulator is a rigid body. Stress is treated three dimensionally in the isotropic linearly-elastic links, but the in-plane and out-of-plane warpings of the links’ cross-sections are neglected. Although the links’ cross-sections undergo negligible elastic orientation, their models are more accurate than a nonlinear 3D Euler–Bernoulli beam. Tension, compression, twisting and spatial deflections of each link are coupled to each other by some nonlinear terms including two new ones. In the issue of flying flexible-link manipulators new terminologies, namely forward/inverse kinetics instead of forward/inverse kinematics are suggested, since determination of position and orientation of the end-effector is coupled to the partial differential motion equations.     

目标拦截模拟系统中的造型方法

对目标拦截模拟系统中的造型技术作了研究.包括飞行器造型、地形造型、火焰喷射模拟等.提出了蒙皮技术造型中存在的三个问题及相应改进措施.给出了一个基于蒙皮技术的地形生成新算法.利用嵌套圆台扰动的思想较好地实现了导弹飞行时的火焰喷射模拟.     

Geometrical shape comparison by size theory

Size Theory allows us to compare shapes of topological spaces and manifolds with respect to properties described by real functions. The main tools used in Size Theory are some pseudo-distances measuring the minimal changes of these real functions under the action of homeomorphisms. This method can be adapted to several different definitions of shape without changing its geometrical-topological framework. Some new results about this approach to shape comparison are illustrated. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On optimization of the RBF shape parameter in a grid-free local scheme for convection dominated problems over non-uniform centers

Global optimization techniques exist in the literature for finding the optimal shape parameter of the infinitely smooth radial basis functions (RBF) if they are used to solve partial differential equations. However these global collocation methods, applied directly, suffer from severe ill-conditioning when the number of centers is large. To circumvent this, we have used a local optimization algorithm, in the optimization of the RBF shape parameter which is then used to develop a grid-free local (LRBF) scheme for solving convection–diffusion equations. The developed algorithm is based on the re-construction of the forcing term of the governing partial differential equation over the centers in a local support domain. The variable (optimal) shape parameter in this process is obtained by minimizing the local Cost function at each center (node) of the computational domain. It has been observed that for convection dominated problems, the local optimization scheme over uniform centers has produced oscillatory solutions, therefore, in this work the local optimization algorithm has been experimented over Chebyshev and non-uniform distribution of the centers. The numerical experiments presented in this work have shown that the LRBF scheme with the local optimization produced accurate and stable solutions over the non-uniform points even for convection dominant convection–diffusion equations.