Numerical investigation on characteristics of interfacial wave of liquid film in gas-liquid two-phase flow using OpenFOAM

Liquid film cooling as an advanced cooling technology is widely used in space vehicles.Stable operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket engines.The stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right now.How to improve the stability of thin film has become a hot spot.In view of this,an advanced model based on the conventional Volume of Fluid(VOF) model is adop...     

Secondary trading of airport slots: Issues and challenges

Most Level 3 airports around the world suffer severe congestion and flight delays. Airlines have to obtain airport slots in order to schedule flights at such airports. The main way for airlines to acquire slots is primary slot allocation, in which a slot coordinator distributes slots to airlines according to certain rules and regulations. Due to excessive demand for slots and restrictions on allocation rules, it is difficult for some airlines to obtain the desired slots in this manner.Another wa...     

State-of-the-art development about cryogenic technologies to support space-based infrared detection

As a key technology for space-based Earth observation and astronomical exploration,cooled mid-wavelength and long-wavelength Infrared(IR) detection is widely used in national defense, astronomy exploration, medical imaging, environmental monitoring, agricultural and other areas. The performances of IR detectors, including cut-off wavelength, detectivity, sensitivity and temperature resolution, plays a significant role in efficiently observing and tracking the low-temperature far-distance moving ...     

Strict finite-time sliding mode control for a tethered space net robot

Tethered Space Net Robot(TSNR) is considered to be a promising approach for space debris removal, and accordingly it is also an interesting control problem due to its time-varying disturbances caused by an elastic and flexible net and a main connected tether. In this situation, the control scheme should be robust enough, low-frequency, and finite-time convergent in presence of external disturbances. In this paper, a robust controller with an advanced adaptive scheme is proposed. To improve robus...     

Experimental investigation on aerodynamic and noise characteristics of Fenestron

It is difficult to simulate the strong interference and serious flow separation of Fenestron by the CFD method based on the widely used RANS equation, and the detailed experimental data, which could be used to validate the aerodynamic and noise numerical methods, is unavailable. The experimental investigation on the aerodynamic and noise characteristics of Fenestron is carried out. In view of the complex internal flow field in duct and the relative motion between the stationary duct and the rota...     

Distributed coordinated control scheme of UAV swarm based on heterogeneous roles

This paper proposes a new distributed coordinated control scheme based on heterogeneous roles for Unmanned Aerial Vehicle(UAV) swarm to achieve formation control. First, the framework of the distributed coordinated control scheme is designed on the basis of Distributed Model Predictive Control(DMPC). Then, the effect of heterogeneous roles including leader, coordinator and follower is discussed, and the role-based cost functions are developed to improve the performance of coordinated control for...     

Resilience optimization for multi-UAV formation reconfiguration via enhanced pigeon-inspired optimization

This paper develops a novel optimization method oriented to the resilience of multiple Unmanned Aerial Vehicle(multi-UAV) formations to achieve rapid and accurate reconfiguration under random attacks. First, a resilience metric is applied to reflect the effect and rapidity of multi-UAV formation resisting random attacks. Second, an optimization model based on a parameter optimization problem to maximize the system resilience is established. Third, an Adaptive Learning-based Pigeon-Inspired Optim...     

Pressure-induced instability and its coupled aeroelasticity of inflated pillow

A floating air weapon system(such as airborne floating mines) plays an important role in modern air defense operations. This paper focuses on aeroelastic characteristics of airborne floating mine named inflated pillow. Firstly, the dynamic deployable process of the pillow and characteristics of the local instability of the edge are studied, and the evolution mechanism of wrinkles and kinks is analyzed. Secondly, in the cruising stage, the fluid-structural-thermal coupling analysis is performed o...     

Development of New Capabilities Using Machine Learning for Space Weather Prediction

With the development of space exploration and space environment measurements, the numerous observations of solar, solar wind, and near Earth space environment have been obtained in last 20 years. The accumulation of multiple data makes it possible to better use machine learning technique, which has achieved unforeseen results in industrial applications in last decades, for developing new approaches and models in space weather investigation and prediction. In this paper, the efforts on the forecasting methods for space weather indices, events, and parameters using machine learning are briefly introduced based on the study works in recent years. These investigations indicate that machine learning, especially deep learning technique can be used in automatic characteristic identification, solar eruption prediction, space weather forecasting for solar and geomagnetic indices, and modeling of space environment parameters.      

First-principle Calculations of V/Fe Doped Anatase TiO_2

The electronic structures of the titanium dioxide(TiO2) doped with V and Fe were analyzed by using first-principle calculations based on the density functional theory(DFT) with the full potential linearized augmented plane wave method (FP-LAPW). The fully optimized structure and the relaxation introduced by impurity were obtained by minimizing the total energy and atomic forces. The unit cell of the V-doped anatase TiO2 is smaller than that of the non-doped one, but for the Fe-doped one, the case is just the opposite. It is found that the apical Ti-O and impurity-O bond lengths of the V/Fe-doped anatase TiO2 are greater than those of the non-doped structure, but smaller for the equatorial bond length. Through the band structures and the density of states, the V-doped TiO2 is shown to be a kind of half-metal, while the Fe-doped TiO2 a kind of metal. The magnetic moments of the V/Fe-doped system are mainly generated by the dopants. The results may be helpful for us to understand the experimental outcome of this system.