摘要：A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.

摘要：对高速边界层转捩与湍流的理解、建模与控制不但具有广泛的学术兴趣,而且对高速飞行器的设计与节能有至关重要的意义,因为转捩和湍流会急剧增加壁面摩阻和热流.根据Morkovin假设,高速流动具有一些与不可压缩流动本质上相似的特征,但另一方面,由于存在热力学过程、激波、高焓效应等多物理场耦合,与不可压缩流动也有显著区别.本文综述了高速边界层转捩与湍流的物理和建模方面的最新研究进展,其中较大部分内容为湍流研究.为了物理过程描述的完整性,我们首先简要综述了高速流动转捩,主要关注气动加热原理和推迟转捩的被动控制策略.随后,我们总结了近期在湍流平均流向速度和温度的标度率方面的一些令人鼓舞的发现,这些标度率能够用于构建一系列新颖的壁面模型以提高模式精度.此外,作为湍流建模的基础之一,我们还总结了湍流结构方面的研究,尤其关注边界层对数区含能运动的标度率与建模.另外,我们综述了各种用于预测壁湍流的线性模型.尽管湍流通常被认为是高度非线性的,这些线性模型在过去二十年的研究中取得了较大的成功.最后,我们对综述进行总结,并简要展望未来研究.

摘要：Aiming at dealing with the difficulty for traditional emergency rescue vehicle(ECV)to enter into limited rescue scenes,the electro-hydraulic steer-by-wire(SBW)system is introduced to achieve the multi-mode steering of the *** overall structure and mathematical model of the SBW system are described at *** fractional order proportional-integral-derivative(FOPID)controller based on fractional calculus theory is designed to control the steering cylinder’s movement in SBW *** anti-windup problem is considered in the FOPID controller design to reduce the bad influence of *** parameters of the FOPID controller are optimized using the genetic algorithm by maximizing the fitness function which involves integral of time by absolute value error(ITAE),peak overshoot,as well as settling *** time-domain simulations are implemented to identify the performance of the raised FOPID *** simulation results indicate the presented FOPID controller possesses more effective control properties than classical proportional-integral-derivative(PID)controller on the part of transient response,tracking capability and robustness.

摘要：This paper presents the fundamentals of a continuous adjoint method and the applications of this method to the aerodynamic design optimization of both external and internal *** formulation of the continuous adjoint equations and the corresponding boundary conditions are *** the adjoint method,the complete gradient information needed in the design optimization can be obtained by solving the governing flow equations and the corresponding adjoint equations only once for each cost function,regardless of the number of design *** inverse design of airfoil is firstly performed to study the accuracy of the adjoint gradient and the effectiveness of the adjoint method as an inverse design *** the method is used to perform a series of single and multiple point design optimization problems involving the drag reduction of airfoil,wing,and wing-body configuration,and the aerodynamic performance improvement of turbine and compressor blade *** results demonstrate that the continuous adjoint method can efficiently and significantly improve the aerodynamic performance of the design in a shape optimization problem.

摘要：An integrated program was established to design a combustor for a liquid rocket engine and to analyze regenerative cooling results on a preliminary design *** of burnt gas from a kerosene-LOx mixture in the combustor and rocket performance were calculated from CEA which is the code for the calculation of chemical *** heat transfer of regenerative cooling was analyzed by using SUPERTRAPP code for coolant properties and by one-dimensional correlations of the heat transfer coefficient from the combustor liner to the *** of the combustors of F-1 and RS-27A engines were designed from similar input data and the present results were compared to actual data for ***,the combustors of 30 tonf class,75 tonf class and 150 tonf class were designed from the required thrust,combustion chamber,exit pressure and mixture ratio of *** wall temperature,heat flux and pressure drop were calculated for heat transfer analysis of regenerative cooling using the profiles.

摘要：Our small planet is now vulnerable to the cumulative effects of our normal activities. There are two specific grand challenges associated with sustainability that are worth our attention-the global carbon cycle and the global nitrogen cycle. Human beings are disrupting the carbon cycle by releasing carbon, dug out of coalmines and oil fields, into the atmosphere.

摘要：Extensibility and attainability of topology optimization are discussed by investigating a variety of simultaneous topology opti-mization methods extended from the standard ***,the state of the art is highlighted through systematic classification of developed methods,such as simultaneous topology optimizations of microstructure and macrostructure,structure and supports,structure and design-dependent loads,structure and locations of involved ***,some recent results about simultaneous topology optimization of structure and applied loads are *** is shown that the simultaneous topology optimization is an integrated methodology that extends the concept of standard topology optimization in the sense of systematic *** presence of more than one kind of design variable of different nature makes the optimization problem complex but enlarges the design space to attain the optimization.

摘要：Soft machines are combinations of hard and soft active materials, thus the coupling and interaction between soft and hard components dictate the performance of soft machines. Structural optimization has been intensively used for design of conventional hard machines, while, to our best knowledge, few attempts have been made towards optimal design of soft machines. Here, we describe the sizing optimization problem of a dielectric elastomer(DE) actuated mechanical amplifier, and achieve the optimal design through combination of a commercial finite element method(FEM) software and an optimization automation *** then design, fabricate and demonstrate a locomotive soft machine driven by DE actuator with amplified displacement *** methodology and results present here open the door towards optimal designs of active materials based soft machines.

摘要：Bone cancer is a critical health problem on a global scale,and the associated huge clinical and economic burdens are still *** many clinical approaches are currently used for bone cancer treatment,these methods usually affect the normal body functions and thus present significant ***,advanced materials and additive manufacturing have opened up promising avenues for the development of new strategies targeting both bone cancer treatment and post-treatment bone *** paper presents a comprehensive review of bone cancer and its current treatment methods,particularly focusing on a number of advanced strategies such as scaffolds based on advanced functional materials,drug-loaded scaffolds,and scaffolds for photothermal/magnetothermal ***,the main research challenges and future perspectives are elaborated.

摘要：3D computer-aided design (CAD) systems based on feature-based solid modelling technique have been widely spread and used for product design. However, when part models associated with features are used in various downstream applications, simplified models in various levels of detail (LODs) are frequently more desirable than the full details of the parts. In particular, the need for feature-based multiresolution representation of a solid model representing an object at multiple LODs in the feature unit is increasing for engineering tasks. One challenge is to generate valid models at various LODs after an arbitrary rearrangement of features using a certain LOD criterion, because composite Boolean operations consisting of union and subtraction are not commutative. The other challenges are to devise proper topological framework for multiresolution representation, to suggest more reasonable LOD criteria, and to extend applications. This paper surveys the recent research on these issues.