Characterising the variables associated with Tribolium castaneum adults that initiate flight in laboratory tests – Generating predictions for the field

The flight behaviour of Tribolium castaneum was studied in the laboratory by characterising the physiological factors related to flight initiation in these small but long-lived beetles. We investigated the flight propensity of T. castaneum at two different ages at the same time: old beetles (∼12 weeks post-emergence) and young ones (∼2 weeks post-emergence). A mixture of old and young individuals was used as an independent test of whether flying beetles had the same characteristics as young beetles and residents the same ones as old. First generation laboratory cultures of field-collected beetles were used to avoid the known effects of protracted laboratory culturing. Beetles that initiated flight were captured individually in the laboratory using a customized trap, and their age, sex, weight, size, fat content, fecundity, and lipofuscin intensity (as a potential correlation of age) were determined. Beetles that had not flown in the test were simultaneously collected to represent residents (non-flyers) in each treatment. The assays indicated that flight propensity declined significantly with age (more young beetles flew than old ones), was not related to sex or weight, but was associated with size (larger beetles flew more). Lipofuscin intensity of old beetles was similar to that of young beetles, so is not a good indicator of age, but it was significantly higher in young flying females than young resident ones, so may be related to metabolic status. Fecundity assessments on a subset of the captured beetles indicate that total fecundity was not related to age or flight propensity. Based on these results we predict that most of the flying T. castaneum in the field will be relatively young beetles of high fat content. These individuals are likely to live longer than older beetles although the fecundity of females will not be higher.     

Structural load alleviation using distributed delay shaper: Application to flexible aircraft

Lightweight flexible aircraft suffers from unwanted oscillatory vibrations during aircraft manoeuvres. A recently developed distributed-delay signal (DZV) shaper is therefore proposed to be applied as a feedforward controller to alleviate the manoeuvre loads, as an alternative to traditional structural filters used routinely in this context. Structural filters are essentially linear low-pass filters with bandwidth below the significant flexible modes, applied to control signals generated either by the pilot’s direct input or by the flight control system. It has been showed that if instead a properly tuned signal shaper is used, better performance can be achieved: first, the target modes are significantly attenuated while the responsiveness of the aircraft is less compromised and secondly, the oscillatory nature of the vibrations are reduced. The high fidelity simulation results on a full scaled dynamic model of a highly flexible blended wing–body (BWB) aircraft show that in comparison to traditional structural filters, signal shapers significantly reduce the wing root loading (forces and moments) which provides potential structural benefits.     

Flight control of a hexa-rotor airship: Uncertainty quantification for a range of temperature and pressure conditions

The present paper is concerned with the dynamic modeling and design of control laws for a small non-rigid multi-rotor airship constituted of an oblate-spheroid helium balloon coupled with an electric-powered hexa-rotor airframe. The vehicle is assumed to operate in windless and low-speed conditions. A six-degree-of-freedom nonlinear dynamic model is derived for it using the Newton–Euler approach and considering, among other efforts, a restoring torque due to the displacement of the balloon’s center of buoyancy above the vehicle’s center of mass and the added-mass effect resulting from the air–structure interaction. Using the derived model and assuming a time-scale separation between the translational and rotational dynamics, the attitude and position control laws are designed separately from each other. Both laws are formulated using feedback linearization combined with control input saturation within appropriate parallelepipedal sets, which are carefully chosen to respect pre-defined bounds on the control torque, control force and maximum inclination angle. The effect of temperature and pressure fluctuations is taken into account through a parametric probabilistic approach, where Maximum Entropy Principle is used to construct a physically consistent stochastic model and Monte Carlo method is used as the stochastic solver to propagate the uncertainties through the system. Extensive simulation results show the effectiveness of the proposed control system and quantify the uncertainty of its performance over a wide range of local temperature and pressure.     

组合式火箭爆破器系统飞行性算法研究

为提高爆炸带的展直率,确保火箭爆破器的破障效果,建立二维有限质点模型对火箭爆破器系统的飞行特性进行研究。根据力学方程、运动方程和几何连续方程,通过时间差分法对各质点的力学参数进行数值计算,并结合实验工况对火箭爆破器系统在空中飞行的力学特性进行计算分析。结果表明:在主动段中,火箭拖拽爆炸带加速运动,爆炸带保持直线拉直状态;爆炸带全部拉出后,由于阻力伞的作用,爆炸带的内力较大,仍能维持在展直状态;进入被动段后,随着火箭及爆炸带速度的下降,阻力伞对爆炸带的拉力随之下降,爆炸带在越过最高点后,下落的阶段容易发生弯曲。     

Neural network-based flight control systems: Present and future

As the first review in this field, this paper presents an in-depth mathematical view of Intelligent Flight Control Systems (IFCSs), particularly those based on artificial neural networks. The rapid evolution of IFCSs in the last two decades in both the methodological and technical aspects necessitates a comprehensive view of them to better demonstrate the current stage and the crucial remaining steps towards developing a truly intelligent flight management unit. To this end, in this paper, we will provide a detailed mathematical view of Neural Network (NN)-based flight control systems and the challenging problems that still remain. The paper will cover both the model-based and model-free IFCSs. The model-based methods consist of the basic feedback error learning scheme, the pseudocontrol strategy, and the neural backstepping method. Besides, different approaches to analyze the closed-loop stability in IFCSs, their requirements, and their limitations will be discussed in detail. Various supplementary features, which can be integrated with a basic IFCS such as the fault-tolerance capability, the consideration of system constraints, and the combination of NNs with other robust and adaptive elements like disturbance observers, would be covered, as well. On the other hand, concerning model-free flight controllers, both the indirect and direct adaptive control systems including indirect adaptive control using NN-based system identification, the approximate dynamic programming using NN, and the reinforcement learning-based adaptive optimal control will be carefully addressed. Finally, by demonstrating a well-organized view of the current stage in the development of IFCSs, the challenging issues, which are critical to be addressed in the future, are thoroughly identified. As a result, this paper can be considered as a comprehensive road map for all researchers interested in the design and development of intelligent control systems, particularly in the field of aerospace applications.     

谈信息设备招标技术文件的编制

介绍了国际机场航站楼公共广播和内部通讯系统的技术招标书的编写格式，及工程要求达到的技术性能指标。     

一种空间飞行轨迹的大地坐标计算方法

针对弹道飞行器空间飞行轨迹的大地坐标计算,从弹道计算的地心球坐标出发,给出一种利用空间几何关系的迭代法,避免了地心直角坐标的转换过程。通过与传统算法的对比分析,验证了该算法的有效性,并进一步明确了该算法的迭代初值,分析了该算法在弹道飞行器空间飞行轨迹大地坐标计算中的适用性。     

基于Pro/E二次开发的飞行器质量特性计算技术

为了计算复杂飞行器的质量特性,利用Visual Studio2010开发环境和Pro/E自带的Pro/ToolKit开发模块进行二次开发。采取异步模式调用Pro/E,计算飞行器系统及零部件的质量特性参数并保存至数据库,支持按零件、组合部件和飞行器整体状态的质量特性输出,并提供一种质量特性的修改方法。结合虚拟飞行器模型,验证了飞行器质量特性计算系统的准确性和实用性,质量特性的计算效率得到提高。     

Study of pilot's comfortness in the cockpit seat of a flight simulator

Pilot's seat cushion parameters on seating comfort have been investigated using finite element approach. Various parameters such as stiffness and thickness have been considered to study the seating comfort. Uniaxial compression test has been conducted on seat cushion foam to establish the stress-strain relationship. This stress-strain test data has been used for selection of appropriate hyper-elastic model and extraction of material model parameter by using curve fitting. Simplified models of human buttock, pelvic bones and cushion foam have been developed to simulate the mechanical response of cushion foam under gravity load. The result of finite element analysis has been found in good agreement with computational results related to contact stress at interface of buttock-seat cushion available in literature.     

The dispersal flight of Tribolium castaneum – A field test of laboratory generated predictions

The reasons for Tribolium castaneum undertaking dispersal flight in the field are poorly known. The research reported here was designed to test, in the field, the predictions generated from our previous laboratory study about the dispersal flight of T. castaneum beetles. The results of that laboratory study suggested that younger beetles with large bodies and higher fat content tend to fly more frequently, and female flyers are likely to live longer with a higher lifetime fecundity relative to those beetles that remain. These predictions were tested by sampling beetles flying within storage and at various distances (20 and 300 m) from a large population infesting stored cotton seed. Beetles were also collected directly from the infested cotton seed as a representation of ‘resident beetles’. Of the adults collected, a subset was weighed and measured, and others were tested for their fecundity, fat content and lipofuscin levels. The survival and total fecundity of females (until day 105 post-emigration) was statistically similar across the treatments, but access to males later in life (i.e. after day 105), to a subset of females from each treatment, increased their fecundity (except for those trapped at 300 m). The majority of females that were caught dispersing are presumed to be relatively young, multiply mated, and produced numerous offspring (mean = 307.3) in the absence of males. Fat content was significantly higher across flying beetles (both sexes) trapped at 2 m (within the shed) compared to flying beetles trapped at longer distances. Flight propensity was evidently not influenced by sex, weight or body size. The lipofuscin intensities of flyers was generally significantly higher than those of resident males and females, although a reliable estimate of their age would add significant value to spatio-temporal studies in these beetles. These findings have implications for management of phosphine resistance.