基于模糊逻辑的导弹扩展比例导引律

临近空间高超声速大机动目标的拦截制导律一直是现代制导与控制方面的一个难点和热点。运用模糊逻辑的方法，改进了扩展比例导引律，使导弹在拦截过程中能够有效跟踪导弹至目标视线转率的变化及目标的机动加速度，拦截末段视线转率收敛，实施成功拦截。     

Impact of carbon fibre/epoxy corrugated cores

The dynamic compressive response of corrugated carbon-fibre reinforced epoxy sandwich cores has been investigated using a Kolsky-bar set-up. Compression at quasi-static rates up to v₀ = 200 ms⁻¹ have been tested on three different slenderness ratios of strut. High speed photography was used to capture the failure mechanisms and relate these to the measured axial compressive stress. Experiments show significant strength enhancement as the loading rate increases. Although material rate sensitivity accounts for some of this, it has been shown that the majority of the strength enhancement is due to inertial stabilisation of the core members. Inertial strength enhancement rises non-linearly with impact velocity. The largest gains are associated with a shift to buckle modes composed of 2–3 half sine waves. The loading rates tested within this study are similar to those that are expected when a sandwich core is compressed due to a blast event.     

First results with the upgraded TLK tritium calorimeter IGC-V0.5

At Tritium Laboratory Karlsruhe (TLK) calorimetry has been used for almost 20 years as the main accountancy method for tritium inventory. An extensive work has been carried out in order to improve the existing calorimeters. This paper covers the efforts made for the upgrade of the IGC-V0.5 calorimeter. We replaced the hardware interface – including the obsolete PC – and developed a new control and data acquisition software. The new software applies a smart automatic process control during measurements, significantly reducing measurement time and possible user errors. The three PID control loops have been re-tuned using the standard closed loop Ziegler–Nichols procedure to find the optimal PID parameters. Five calibration runs have been performed between 0.5 μW and 1 W, and their results are being presented and discussed.     

Visual–inertial navigation for pinpoint planetary landing using scale-based landmark matching

Landing an autonomous spacecraft within 100 m of a mapped target is a navigation challenge in planetary exploration. Vision-based approaches attempt to pair 2D features detected in camera images with 3D mapped landmarks to reach the required precision. This paper presents a vision-aided inertial navigation system for pinpoint planetary landing called LION (Landing Inertial and Optical Navigation). It can fly over any type of terrain, whatever the topography. LION uses measurements from a novel image-to-map matcher in order to update through a tight data fusion scheme the state of an extended Kalman filter propagated with inertial data. The image processing uses the state and covariance predictions from the filter to determine the regions and extraction scales in which to search for non-ambiguous landmarks in the image. The image scale management process operates per landmark and greatly improves the repeatability rate between the map and descent images. A lunar-representative optical test bench called Visilab was also designed in order to test LION. The observability of absolute navigation performances in Visilab is evaluated with a model developed specifically for this purpose. Finally, the system performances are evaluated at a number of altitudes along with its robustness to off-nadir camera angle, illumination changes, a different map generation process and non-planar topography. The error converges to a mean of 4 m and a 3-RMS dispersion of 47 m at 3 km of altitude on the test setup at scale.     

Improved Kalman-based attitude estimation framework for UAVs via an antenna array

Accurate attitude estimation is crucial for Unmanned Aerial Vehicles (UAVs) in order to facilitate automated activities such as landing or trajectory tracking. Recently antenna array based communication systems have been installed in UAVs. This array structure can also be applied for attitude estimation by computing the line-of-sight (LOS) path between the base station and UAV. In this paper, we propose a complete framework for attitude estimation by exploiting 3D LOS vector obtained from the antenna array system. We present all the steps to incorporate the estimated LOS vector into the TRIaxial Attitude Determination (TRIAD), QUaternion ESTimator (QUEST) and Kalman algorithms. As an additional contribution, the error covariance matrix of the LOS vector is analytically calculated by first finding the phase shift mean squared error using the known perturbation model from Singular Value Decomposition and assuming that the antenna array measured data error can be modeled as a circularly symmetric white noise. We evaluate five array configurations via Monte Carlo simulations. We show that array configurations that provide orthogonal components of the LOS vector achieve a better performance. The usage of more than three pairs of antennas to improve the estimation of the LOS vector is also proposed for low and intermediate signal-to-noise ratio regimes.     

Designing the NGC system of a small ASV for tracking underwater targets

The paper describes the development of the Navigation, Guidance and Control system of a small, prototypal Autonomous Surface Vehicle (ASV), which is part of an ASV/UUV (Unmanned Underwater Vehicle) robotic system. The main task of the ASV is to serve as supply vessel for the UUV it can carry, deploy and recover and to allow communication with a remote control station. The main problem the NGC system has to handle is that of making the ASV track the UUV and maintain the relative distance within a given bound, using delayed information about the UUV position provided by an acoustic tracking and positioning systems. The specific tracking problem is formulated in a suitable way and a strategy for its solution is proposed and implemented by means of an appropriate control architecture. Stability is discussed using Lyapunov techniques and performances are shown by means of simulations.     

Adaptive internal model guidance law for weaving maneuvering target

For the terminal phase guidance problem of the missile intercepting weaving maneuvering target, an adaptive internal model guidance laws in the three-dimensional (3-D) engagement space is proposed in this paper. The guidance law adopts the disturbance rejection theory by treating the target weaving maneuvering accelerations as external disturbance, which comprises of nominal part and adaptive part. The nominal part based on feedback linearization method ensures the whole guidance system stable and the adaptive part based on internal model principle is used to recover the disturbance signals on-line to reject the target maneuver asymptotically. The algorithm guarantees the whole guidance system with satisfying performance both in transient and steady state on the effect of target maneuver on guidance system. The stability analyses and theory proof are provided in this paper. At last, numerical simulations are carried out to illustrate the effectiveness of the proposed guidance law.     

Particulate character, inertial effects and diffusion effects in concentrated suspensions

In the sedimentation of suspensions, the particles modify their settling velocity in accordance with the solids concentration. Kynch's theory assumes that in each layer, the settling velocity only depends on the solids concentration, and neglects the acceleration and deceleration processes when the particles descend with a velocity distinct from that corresponding to the solids concentration at this layer. The Kynch theory also assumes that there are so many small particles that the solid mass can be considered homogeneously distributed in the suspension, so the particulate character of the suspension is ignored. Kynch's theory also neglects the diffusion effects. An analysis of the particulate character of the suspension, the inertial effects and the diffusion effects are discussed in this paper, deducing a critical value for considering the particulate character negligible and a critical size for considering the diffusion effect also negligible. Finally, several data of different flocculated suspensions are satisfactorily analysed in view of the conclusions obtained previously.     

规划·规范·规则:深圳开发控制三大体系的互动关系

规划、规范和规则是建设项目审批依据的三个基本来源,三者共同构成开发控制管理制度的三大核心体系。研究结合深圳实践,阐述三大体系的特征、构成和分类,分析三者在静态条件下的优先关系和在动态条件下的互动关系,尝试揭示三大体系之间相互替代、补充、促进、转化和融合的演化规律。     

TC4钛合金惯性摩擦焊接头组织及断裂韧性与裂纹扩展特性分析

文章采用了XRD、SEM、EBSD等显微表征技术分析了焊态及焊后热处理态下焊接接头各区域的微观组织特征,并研究了焊接接头的断裂韧性和疲劳裂纹扩展性能。结果表明,焊缝区以再结晶组织为主,热力影响区等轴状初生α_p相转变为棒状结构,热影响区组织与母材基本相同,热力影响区与热影响区的原始β晶粒内部分区域形成了取向差角度约为60°的针状马氏体α′相,热处理促进了残余亚稳态β相分解,在片状α_s相间形成了大量断续分布组织。焊缝区α晶粒内大量的平行或交叉分布的片状α相和复杂的相界面结构可有效阻碍裂纹的扩展并改变裂纹的扩展路径,提高焊接接头的断裂韧性及抗疲劳裂纹扩展能力。