摘要：昆虫和微型飞行器存在间隙狭窄的串列式拍动翼-固定翼构型.与独立的拍动翼相比,两翼之间的干扰作用可以增强推力,但推力增量能否通过倾斜拍动平面而转化为升力尚不清楚.本文采用浸润边界法和格子玻尔兹曼方法研究了这种串列双翼构型在不同拍动平面倾角下的气动性能。结果表明,当拍动平面倾角为75°时,干扰作用产生的大部分推力增量转化为升力增量,证明了通过倾斜拍动平面实现升推转化的可行性。除了几何投影和有效迎角改变的贡献外,升力增量还来自于两翼位置最接近时的额外升力峰,其流动机制包括两部分:一方面,固定翼阻碍了拍动翼产生的射流并在间隙内产生了较强的水平回流,从而增强了拍动翼上翼面后缘附近的低压区;另一方面,固定翼前方的上洗气流增强了拍动翼下翼面的高压区.进一步分析表明,这种增升机制在多个拍动幅度下有效,因此可以认为该机制在三维构型中仍然存在。上述研究结果揭示了一种通过倾斜拍动平面来增强串列式拍动翼-固定翼构型升力的新机制,为以这种构型为基础的微型飞行器提供了新设计方案.

摘要：A dynamic programming-sequential quadratic programming(DP-SQP)combined algorithm is proposed to address the problem that the traditional continuous control method has high computational complexity and is easy to fall into local optimal *** solve the globally optimal control law sequence,we use the dynamic programming algorithm to discretize the separation control decision-making process into a series of sub-stages based on the time characteristics of the separation allocation model,and recursion from the end stage to the initial *** sequential quadratic programming algorithm is then used to solve the optimal return function and the optimal control law for each *** simulations of the combined algorithm and the traditional algorithm are designed to validate the superiority of the combined ***-following and cross-conflict simulation examples are created to demonstrate the combined algorithm’s adaptability to various conflict *** simulation results demonstrate the separation deploy strategy’s effectiveness,efficiency,and adaptability.

摘要：A set of acoustic optimization design methods is established by combining the flow field deterioration theory and the acoustic analogy theory,and applied to the acoustic optimization design of high-speed train *** results show that the streamline bodies of the head/tail car are the most important sound sources,respectively,accounting for 23.7%and 33.7%of the total sound *** with the streamline body of tail head,the streamline body of head car is more biased towards high frequency for the sound source *** A-weighted radiated noise of the train body is characterized by broadband sound(mainly in the range of 1-4 kHz)and peak features(especially at 2 kHz).The snow-plough with the maximum expansion length can mitigate the strong peak effect of the sound at 2 kHz,reduce the total sound energy,and show the best acoustic radiation performance in the four *** numerical computation model was checked by the wind tunnel test results.

摘要：Wave transmission and overtopping around nearshore breakwaters can have significant influence on the transmitted wave parameters,which affects wave conditions and sediment transportation and becomes the focus of design in *** objective of this paper is to present a simplified model to estimate these important wave *** paper describes the incorporation of wave transmission and overtopping module into a wave model for multi-directional random wave transformation based on energy balance equation with the consideration of wave shoaling,refraction,diffraction,reflection and ***'s frequency spectrum and non-linear dispersion relation are also included in this *** influence of wave parameters of transmitted waves through a smooth submerged breakwater has been considered in this model with an improved description of the transmitted wave spectrum of van der Meer et al.(2000) by Carevic et al.(2013).This improved wave model has been validated through available laboratory *** the verified model is applied to investigate the effect of wave transmission and overtopping on wave heights behind low-crested breakwaters in a project for nearshore *** calculations are carried out with and without consideration of the wave transmission and overtopping,and comparison of them indicates that there is a considerable difference in wave height and thus it is important to include wave transmission and overtopping in modelling nearshore wave field with the presence of low-crested ***,this model can provide a general estimate of the desired wave field parameters,which is adequate for engineers at the preliminary design stage of low-crested breakwaters.

摘要：In order to achieve an access to strain sensor data with wireless transmission in bridge engineering structure testing, a wireless strain test system is presented based on the resistance strain sensor of networks. The wireless bridge strain test system composed of master station and substation adopts the wireless method to realize the high accuracy data acquisition between the master station and the substation under a reliable communication protocol. The system has been tested in contrast with the present strain apparatus. Results show that the wireless system is high-reliable, and has many characteristics such as high efficiency, good precision, high stability with low cost, and good flexibility, without using the present communication network.

摘要：受最新材料科学、计算机技术、人工智能和自动控制技术的启发,新一代交通基础设施正在走向数字化和智能化。世界上许多主要发达国家都在因地制宜,积极推动智能创新技术在交通基础设施中的应用。本文首先简要介绍了交通基础设施智能化的基本概念、科学依据和发展历程。然后,按照设计、施工、运维、淘汰的全生命周期链条,系统分析了智能化技术的研究现状和面临的主要挑战。随后,以世界上第一条基于智能建设理念建设的铁路——北京-张家口高铁为例,全面介绍了智能技术的最新成就。最后,从标准体系、理论方法和人才培养三个维度对交通基础设施智能化的未来发展进行了探讨。

摘要：Crimping is widely adopted in the production of large-diameter submerged-arc welding pipes. Traditionally, designers obtain the technical parameters for crimping from experience or by trial and error through experiments and the finite element(FE) method. However, it is difficult to achieve ideal crimping quality by these approaches. To resolve this issue, crimping parameter design was investigated by multi-objective optimization. Crimping was simulated using the FE code ABAQUS and the FE model was validated experimentally. A welding pipe made of X80 high-strength pipeline steel was considered as a target object and the optimization problem for its crimping was formulated as a mathematical model and crimping was optimized. A response surface method based on the radial basis function was used to construct a surrogate model; the genetic algorithm NSGA-II was adopted to search for Pareto solutions; grey relational analysis was used to determine the most satisfactory solution from the Pareto solutions. The obtained optimal design of parameters shows good agreement with the initial design and remarkably improves the crimping quality. Thus, the results provide an effective approach for improving crimping quality and reducing design times.

摘要：A new cascade control program was proposed based on modified internal model control to handle stable,unstable and integrating processes with time *** program had totally four controllers of which the secondary loop had two controllers and the primary loop had two *** two secondary loop controllers were designed using IMC *** were decoupled completely and could be adjusted independently,which avoided the undesirable influence on performance of the primary *** main controller in the primary loop was devised as a PID using the method of minimum sensitivity,which could guarantee not only the nominal performance but also the robust stability of the system.A setpoint filter was added in the primary loop to improve the tracking *** the controllers of the two closed-loops were designed analytically,and could be adjusted and optimized by single parameter *** were carried out on three various processes with time delay,and the results show that the proposed method can provide a better performance of both set-point tracking and disturbance rejection and robustness against parameters perturbation.

摘要：本文研究了一种新型低密度(~6.24 g cm^(-3))双相AlTiVCoNi高熵合金,其组织结构由有序L21高熵金属间化合物、无序体心立方结构和纳米L21相多层次结构构成.该合金在1200℃+24 h热处理下未发生相结构转变,在此条件下具有优异的高温相结构稳定性,其铸态和热处理态的压缩屈服强度相当,达到~1.6 GPa.另外,该合金在室温和600℃条件下表现出了优异的强塑性匹配和优异的比屈服强度,分别达到了约261和210 MPa g^(-1)cm^(3).该合金的超高强度主要源于有序L21相与体心立方相的半共格界面导致的一种强相结构稳定性和多层次结构的复合强化机制.该合金在800和1000℃压缩过程中出现了动态再结晶软化,使得其高温强度有所降低.这种“具有半共格界面L21+体心立方+纳米L21颗粒”的多层次结构设计为开发新型低密度耐高温高熵合金提供了一种新设计思路.