Investigation on in-flight particle velocity in supersonic plasma spraying

In-flight particle velocity and flux distribution were measured using CCD thermal spray monitor system during supersonic plasma spray processing with nano-structured Al_2O_3-TiO_2 feed stocks. According to the results of particle flux measurement, the largest radian of the divergent particle stream is about 0.2. Within the measuring range, top speed of in-flight particles reached 800m/s. Particle acceleration was accomplished within 4cm down stream of the nozzle. Average particle velocity (about 450m/s) exceeded local sound speed (340m/s) even at a mean standoff distance of 17cm. With increasing mean standoff distance, average velocity of in-flight particle decreased according to a parabolic rule approximately. Image diagnosis showed that the result of in-flight particle velocity measurement is credible.

In-flight calibration of the spaceborne fluxgate magnetometer in the Martian magnetosheath

In-flight calibration of the ze ro offset is crucial for ensuring high-precision measure ment of the spaceborne fluxgate magnetomete r.Tianwen-1 is China’s first Mars mission,and its orbiter will re main out of the solar wind for tens of days each year.Previous in-flight calibration methods might not be suitable for this orbiter during such a period.Recently,a new method was proposed by Wang GQ(2022 b),which we refer to as the Wang method Ⅱ for ease of description.Here,we test the performance of this method in the Martian magnetosheath by using magnetic field data measured by the Mars Atmosphere and Volatile EvolutioN(MAVEN) spacecraft.We find that the accuracy of the Wang method Ⅱ is affected by the number of magnetic field subinterval events,the eigenvalues of the minimum variance analysis for each event,and the position of the spacecraft in the magnetosheath.The estimated zero offset varies over a period of~27 days and has a 57.3% probability of accuracy within 2.0 nT.After being smoothed with a temporal window of 27 days,the ze ro offset has a 48.4%(99.3%) probability of accuracy within 1.0(2.0) nT.Our tests suggest that the Wang method Ⅱ provides an option for the Tianwen-1 orbiter to perform in-flight calibration when the orbiter remains out of the solar wind for an extended pe riod of time.

Application of In-Flight Melting Technology by RF Induction Thermal Plasmas to Glass Production

An innovative in-flight glass melting technology with induced thermal plasmas was developed for the purpose of energy conservation and environmental protection. Two-dimensional modeling was used to simulate the thermofluid fields in the plasma torch. The in-flight melting behavior of glass raw material was investigated by various analysis methods. Results showed that the plasma temperature was up to 10000 K with a maximum velocity over 30 m/s, which made it possible to melt the granulated glass raw material within milliseconds. The carbonates in the raw material decomposed completely and the compounds in the raw material attainted 100% vitrification during the in-flight time from the nozzle exit to substrate. The particle melting process is similar to the unreacted-core shrinking model.

Effect of Injection Position on In-Flight Melting Behavior of Granular Alkali-Free Glass Raw Material in 12-Phase AC Arc Plasma

An innovative in-flight glass melting technology with a multi-phase AC arc plasma was developed to save energy and reduce emissions for the glass industry. The effect of the injection position on the in-flight melting behavior of granulated powders was investigated. Results show that the injection position has a strong effect on the melting behavior of alkali-free glass raw material. With the increase in injection distance, the vitrification, decomposition, and particle shrinkage of initial powders are improved. Longer injection distance causes much energy to transfer to particles due to a longer residence time of powder in the high temperature zone. The high vitrification and decomposition degrees indicate that the new in-flight melting technology with 12-phase AC arc can substantially reduce the melting and refining time for glass production.

Unmanned Aerial Vehicles Flight Safety Improvement Using In-Flight Awareness

This paper presents a novel onboard system called In-Flight Awareness Augmentation System (IFA2S) to improve flight safety. IFA2S is designed to semi-automatically (with human supervision) avoid hazards and accidents due to either internal or external causal factors. The requirements were defined in an innovative way using Systems-Theoretic Process Analysis (STPA) method and applied next to model the system. IFA2S increases aircraft awareness regarding both itself and its environment and, at the same time, recognizes platform and operational constraints to act in accordance to predefined decision algorithms. Results are presented through simulations and flight tests using state machines designed to allow the adoption of appropriate actions for the identified hazards. The different decision algorithms are evaluated over as many as possible hazard situations by simulations conducted with software Labview and XPlane flight simulator. Flight tests are performed in a small fixed wing aircraft and make use of a limited version IFA2S, partially attending identified requirements. Results support the conclusion that IFA2S is capable of improving flight safety.

In-flight calibration of the magnetometer on the Mars orbiter of Tianwen-1

Mars orbiter magnetometer(MOMAG)is one of seven science payloads onboard Tianwen-1’s orbiter.Unlike most of the satellites,Tianwen-1’s orbiter is not magnetically cleaned,and the boom where placed the magnetometer’s sensors is not long enough.These pose many challenges to the magnetic field data processing.In this study,we introduce the in-flight calibration process of the Tianwen-1/MOMAG.The magnetic interference including spacecraft generated dynamic field and the slowlychanging zero offsets are cleaned in sequence.Then the calibrated magnetic field data are compared with the data from the Mars atmosphere and volatile Evolutio N(MAVEN).We find that some physical structures in the solar wind are consistent between the two data sets,and the distributions of the magnetic field strength in the solar wind are very similar.These results suggest that the in-flight calibration of the MOMAG is successful and the MOMAG provides reliable data for scientific research.

In-flight performance analysis of the navigation augmentation payload on LEO communication satellite:a preliminary study on WT01 mission

With the development of the Low Earth Orbit(LEO)communication constellations,it has become a hot area of research to provide additional navigation augmentation services.Limited by volume,weight,power consumption,and running time,the in-flight performance of navigation augmentation payload remains to be investigated.In this paper,we analyze the data quality of on-board GNSS observation and evaluate the precision of short-arc dynamic Precise Orbit Determination(POD)performance based on the WangTong-01(WT01)mission.Furthermore,the downlink navigation measurement data of WT01 satellites are analyzed and compared with the GNSS observations.The results show that the average multipath errors of the WT01 on-board GPS L1,L2 and BeiDou Satellite Navigation System(BDS)B1,B2 code observation are 0.54,0.74,0.65,and 0.58 m,respectively.The short-arc dynamic POD three-dimensional(3D)overlapping accuracy is 7.1 cm.The average multipath errors of downlink navigation signal Z1 and Z2 are 0.81 and 0.80 m,respectively,which at the same order of magnitude as GNSS signals.The maximum Carrier-to-Noise Ratio(C/N0)value of WT01 downlink measurement data can reach 60 dB Hz,which is much stronger than GNSS and indicates the navigation signals of LEO satellites can meet the basic requirement of navigation augmentation.

Influence of in-flight particle characteristics and substrate temperature on the formation mechanisms of hypereutectic Al-Si-Cu coatings prepared by supersonic atmospheric plasma spraying

Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight alloys.To find out optimum process conditions and achieve desirable coatings,this work focuses on the influence of three important parameters(in-flight particle temperature,impact velocity,and substrate temperature)on the collected splats morphology coatings microstructure and microhardness.Results show that appropriate combinations of temperature and velocity of in-flight particles cannot only completely melt hypereutectic Al-Si-Cu particles especially the primary Si phase,but also provide the particles with sufficient kinetic energy.Thus,the optimized coating consists of 98.6%of fully-melted region with nanosized coupled eutectic and 0.9%of porosity.Increasing the substrate deposition temperature promotes the transition from inhomogeneous banded microstructure to homogeneous equiaxed microstructure with a lower porosity level.The observations are further interpreted by a newly developed phase-change heat transfer model on quantitatively revealing the solidification and remelting behaviors of several splats deposited on substrate Besides,phase evolutions including the formation of supersaturatedα-Al matrix solid solution,growth of Si and Al_(2)Cu phases at different process conditions are elaborated.An ideal microstructure(low fractions of unmelted/partially-melted regions and defects)together with solid solution,grain refinement and second phase strengthening effects contributes to the enhanced microhardness of coating.This integrated study not only provides a framework for optimizing Al-Si based coatings via thermal spraying but also gives valuable insights into the formation mechanisms of this class of coating materials.

In-flight particle characterization and coating formation under low pressure plasma spray condition

Yttria-stabilized zirconia（ YSZ） coatings were deposited by low pressure plasma spray（ LPPS） in 1.0× 10^4 Pa,1.5 × 10^4 Pa,and 2.5 × 10^4 Pa. Both in-flight particle diagnostic detected by DPV-2000 system and ANSYS-FLUENT software were used to study the connection between the parameters of flying particles and the coating formation,which might help to recognize the relationship between the operation parameters and the coatings quality. The results of simulation showed that particles in a lower spray pressure could achieve a higher velocity. The particle velocity was around 380 m/s at a distance of 35 cm from the nozzle at 1.0 × 10^4 Pa while only 300 m/s at 2.5 × 10^4 Pa in actual measurement.The results showed that the velocity of particles increased with decreasing the spray pressure,which might enhance the flattening rate of coatings and thereby decreased the porosity. The deposited YSZ coating with the lowest porosity can be gained under 1.0 × 10^4 Pa condition.

THALES i5000机载娱乐系统介绍以及常见故障浅析

随着航空业的不断发展,旅客需求的不断提高,机载娱乐系统日益受到各航空公司的重视,纷纷对三大娱乐供应商的系统进行选装,本文主要针对国内某航空公司选装的THALES 5000机载娱乐系统进行介绍,并结合一些常见故障对该套娱乐系统进行系统分析,提出一些修理维护建议,以提高排故效率,缩短排故时间,节约维修成本。帮助航空公司和技术人员更好地维护和优化THALES i5000机载娱乐系统,确保乘客在飞行过程中享受到良好的娱乐体验。

模糊自适应滤波方法在相对导航系统中的应用

编队飞行中需要确定主机和从机之间的相对位置关系,就是要解决导航定位问题。针对无人机在编队飞行过程中由于机动性较大,惯性元器件测量容易出现偏差,进而影响系统的运动状态方程的情况,或者是在系统噪声与观测噪声的统计特性不能够准确得到的情况,提出了一种新的模糊自适应滤波方法。根据实时得到的量测新息的实际方差与理论方差的差值和量测新息的均值,按照判定条件选择适合的滤波方法,然后由设计的模糊推理系统在线实时调整系统噪声和量测噪声矩阵,或是调整状态误差协方差阵即强跟踪滤波,使无人机编队飞行即使在恶劣的环境下依然保持确定的队形不变。仿真结果表明,该算法具有较好的自适应效果。

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang-Pan method

The space-borne fluxgate magnetometer(FGM)requires regular in-flight calibration to obtain its zero offset.Recently,Wang GQ and Pan ZH(2021a)developed a new method for the zero offset calibration based on the properties of Alfvén waves.They found that an optimal offset line(OOL)exists in the offset cube for a pure Alfvén wave and that the zero offset can be determined by the intersection of at least two nonparallel OOLs.Because no pure Alfvén waves exist in the interplanetary magnetic field,calculation of the zero offset relies on the selection of highly Alfvénic fluctuation events.Here,we propose an automatic procedure to find highly Alfvénic fluctuations in the solar wind and calculate the zero offset.This procedure includes three parts:(1)selecting potential Alfvénic fluctuation events,(2)obtaining the OOL,and(3)determining the zero offset.We tested our automatic procedure by applying it to the magnetic field data measured by the FGM onboard the Venus Express.The tests revealed that our automatic procedure was able to achieve results as good as those determined by the Davis-Smith method.One advantage of our procedure is that the selection criteria and the process for selecting the highly Alfvénic fluctuation events are simpler.Our automatic procedure could also be applied to find fluctuation events for the Davis-Smith method.

基于GPS精确制导信息的“天地环境差”研究

结合某惯性制导运载体实际飞行弹道参数GPS解读值和遥测参数值,完整推导了地面静态标定误差系数和实际飞行惯性测量误差系数差异,为惯性制导系统的"天地环境差"研究奠定了基础。

基质辅助激光解吸附飞行时间质谱分析缩合单宁的阳离子化问题

以单价金属离子Cs+和Na+作为离子化试剂,对3种缩合单宁进行基质辅助激光解吸附飞行时间(MALD I-TOF)质谱分析。加入Na+作为阳离子化试剂,能得到较高质量的质谱图。但由于实验通道中几乎不可能完全去除的K+的干扰而会高估棓儿茶酚/表棓儿茶酚单元的组成比例,从而影响对棓儿茶酚/表棓儿茶酚单元存在与否的判断;选择Cs+作为阳离子化试剂可以避免此问题,但在复杂的缩合单宁分析中,同样因为杂质离子Na+和K+的干扰而使得质谱图变得更复杂;未去离子处理直接对缩合单宁进行MALD I-TOF质谱分析与去离子并加入Cs+的处理比去离子并加入Na+能检测到更高聚合度的高聚物,检测到离子峰强度最高的聚合物随离子不同而不同。

通用惯导测试仿真系统的设计与实现

惯导性能测试一般在地面实验平台上进行,只能得到离散状态的测量结果,不能满足分析整个系统性能要求。建立飞行仿真系统能模拟各种飞行模态,并能够对惯导性能进行动态连续飞行轨迹下测试,在工程应用上具有重要意义。提出了惯导性能测试仿真系统的结构框架,并进行了系统功能分析与硬件设计,采用模块化设计思想,构造了基于控制律的飞控仿真模块及惯导反解算、通信等软件模块,给出了详细的设计及实现方法,并使用VC进行算法、系统实现。与惯导系统的联合仿真证明,为惯导测试系统的设计提供有效的平台。

Research on in-light alignment error model based on quaternion and rotation vector

Euler angle error model, rotation vector error model （RVE） and quaternion error model （QE） were qualitatively and quantitatively compared and an in-flight alignment filter algorithm was designed. This algorithm used extended Kalman filter （EKF） based on RVE and QE separately avoi- ding the accuracy problem of the Euler angle model and used Rauch-Tung-Striebel（RTS） smoothing method to refine the accuracy recuperating the coning error for simplified RVE. Simulation results show that RVE and QE are more adapt for nonlinear filter estimation than the Euler angle model. The filter algorithm designed has more advantages in convergence speed, accuracy and stability comparing with the algorithm based on the three models separately.

应用Matlab/Simulink实现传递对准精度评估仿真

论文提出了捷联惯导传递对准精度评估算法的设计方案,并利用Matlab数值计算的强大功能和Simulink建模容易实现的特点进行仿真研究,其中对仿真飞行轨迹和评估滤波器采用Matlab编程实现,惯导系统建模采用Simulink实现,将Matlab程序与Simulink模型进行交互,为捷联惯导传递对准精度评估提供了新的实现途径。仿真结果表明,该方案是可行的,评估是有效的。

GNSS_INS组合导航在飞行校验系统中的应用

目前的飞行校验系统以GPS作为空间基准,这种定位方式在精度、性能、可靠性方面都存在着固有缺陷。介绍的SPAN(synchronous position,attitude and navigation)技术集合了2种不同但互补的技术:GNSS(global navigationsatellite system)定位技术和惯性导航技术。通过二者的结合,SPAN技术可以达到取长补短的目的,组合后的导航系统无论在精度、性能、可靠性方面都优于单独的子系统。将这项技术应用于飞行校验系统,利用GNSS定位的绝对精度加上惯性测量单元(IMU)陀螺和加速计测量的稳定性,就可以在卫星信号丢失或者高动态应用环境下仍然提供持续、稳定、可靠的位置及姿态数据。

结合GPS测姿技术的空中修正方案研究

文中提出一种结合ＧＰＳ载波相位测姿技术对弹上惯导进行空中修正的方案。在导弹飞行过程中，利用ＧＰＳ载波相位测姿技术确定导弹方位，结合位置信息对弹载平台的姿态误差进行修正，使之达到精度要求。文中论述了利用双天线ＧＰＳ接收机的载波相位信号测定载体方位的原理，采用某型国产ＧＰＳ接收机进行了静态实验，验证了使用该型接收机的技术可行性；讨论了利用位置及方位信息估计与修正平台姿态误差的三种方案，给出仿真结果及结论。

精确制导武器惯导系统动态对准技术发展综述

为提高精确制导武器惯导系统(inertial navigation system,INS)动态对准的对准性能,对相关技术进行分析。概述国内外精确制导武器动基座传递对准和外界信息辅助的飞行中组合对准的发展现状,并讨论精确制导武器惯性导航系统动态对准技术的发展趋势。该研究结果表明:通过进一步实现滤波方法改进,寻求更有效的挠曲变形和杆臂效应处理方法,充分利用其他导航信息进行辅助对准和结合具体武器平台机动特性,可有效实现精确制导武器动态对准。