TDOA (Time Difference of Arrival) is a widely used passive positioning technology with high precision, strong ability of collaborating, high robustness. The issues of computational complexity and slow accuracy convergence for the positioning of moving target are addresses. Based on the positioning model in LOS (Line of Sight) environment, a positioning method suitable for a multi-station TDOA system is provided. After linearizing collaboration TDOA positioning relationship equations into a statistical estimation problem, this method online converges iteratively to solutions of targets' locations. A multiplatform collaborative positioning algorithm for different motion characteristics of the targets. Simulations results demonstrate that the provided method can achieve precise positioning. Moreover, the impact of motion patterns on positioning accuracy is analyzed, and simulation results provide guidance for system engineering design.

Taking the hydrogen-oxygen expansion cycle engine as the research object, based on the idea of modular modeling and simulation, the dynamic model of engine components is given, and the liquid rocket engine system model is constructed based on the working principle of the engine system, and the transient state of the hydrogen-oxygen expansion cycle engine is developed simulation Research. According to the simulation results and combined with the test data, the engine system model is verified and optimized, and the optimized model is simulated and calculated in the whole process of engine dynamics. The simulation results show that the main performance parameters during the dynamic change of the engine are in good agreement with the test data, which verifies the simulation model accuracy and design feasibility.

As a high-value military target, it is difficult to directly conduct damage research on real aircraft. Designing equivalent targets to replace real targets in damage tests and simulation research are important means for target vulnerability and damage. A target design method is proposed based on the damage characteristics and usage requirements of equivalent objects, with a focus on the "physical and functional" damage equivalent tecnology of aircraft components/subsystems under the threat of fragments. On this basis, a detailed design process for equivalent targets of aircraft is established by comprehensively considering the equivalence of the target's internal and external environment, as well as various factors such as processing and transportation. Then, based on the proposed method, an equivalent design target is carried out for the radar antenna cover of the early-warning-aircraft (EWA), and ground static explosion damage tests are carried out on the equivalent components. After verifying the accuracy of the simulation method with the test results, the ballistic limit velocity and corresponding critical penetration energy thresholds of diffrerent areas for the typical fragment hitting radar antenna cover are determined through impact finite element simulation, the rationality and usability of the proposed equivalent target design method is verifyed. The equivalent target design method proposed can provide support for the inspection and evaluation of the damage ability of air defense weapons and ammunition, the formulation of aircraft target damage standards, and joint combat training activitis.

Aiming at the rotor axis of PIGA with a zero bias, the transverse acceleration will be coupled to the direction of the input axis to form a cross-coupling error. For the decoupled nonlinear PIGA output expression, the influence of a time-varying input acceleration and the transverse acceleration which is applied to the output are considered, the computing method of PIGA’s output analytic expression relying on the base acceleration of three orthogonal direction and angles of outer axis and rotor shaft as input information is given. On this basis, the model parameters are calibrated by recursive iteration method, in addition to which, the output value compensation method of gyro accelerometer is given. By comparing the error results before and after parameter compensation, the input acceleration error is reduced from ${0.05}\mathrm{\;g}$ to ${0.002}\mathrm{\;g}$, which verifies the effectiveness of the cross coupling error compensation in the output model in the way of improving the measurement accuracy.

The hypersonic vehicle needs to separate from the booster stage in an environment with low altitude and high dynamic pressure. The current prediction of separation and attitude control based on limit deviation method is not real enough and the design is heavily redundant. For inserted separation with long stroke and small gap, the collision detection of two stages cannot be carried out during the attitude control design process. To solve the above problems, a coupling calculating method of separation and attitude control is proposed, which introduces the attitude control model into separation dynamic model. Design redundancy is reduced and the level of refine is improved. Also, collision detection can be realized in the whole process, providing support for ensuring the safety of the separation and attitude control process. The method provides a basis for the time to start attitude control of the upper stage, and has guiding significance for optimization design of separation time sequence.

Along with the surge of radio application, electronic communication in interference environments has become increasingly important. The spectrum sensing technique matters in surmounting the frequency conflict of radio. However, the complex environment hinders the efficient feature extraction from the received spectrum signal and reduces the signal practicality. Recently, the artificial intelligence has been widespread in communication field and crucially influenced the electronic countermeasures. Consequently, based on the deep learning, this work proposes a spectrum sensing method to mix DenseNet and MLP-Mixer. Firstly, the model processes and transforms the spectrum signal data to feature images by Deepinsight Net and the generative adversarial networks renew an image. After obtaining the feature image, aspectrum sensing method integrating DenseNet and MLP-Mixer is used in order to sense the channel occupancy of primary user. Compared with the existing model through ablation experiments, the proposed method improves the detection probability of spectrum sensing better.

To study the safety of a tower slewing platform structure, a three dimensional numerical model is established with actual sizes and operating conditions. The structural force, pressure margin of hydraulic system with different wind loads, and the influence of lift platforms’ amount are researched which are concerned closely in use. In working condition, the maximum stress of structure is ${223.98}\mathrm{{MPa}}$, and the structure safety factor is 1.58 . The pressure margin of hydraulic system is calculated with the worst wind direction and the maximum windward area. When the platform is opened with permitted wind speed, the hydraulic system pressure can not be lower than ${5.40}\mathrm{{MPa}}$, and the pressure margin is 2.96. The structure safety factor is 1.35 when the number of lift platforms is 9. According to the results of simulating calculation, the security of the slewing platform can be confirmed. The simulating model can provide a reference for the slewing platform’s application.

Currently, in fuze two levels of environmental force arming, high dynamic overload is often used as one insurance element. Generally, one arming method is used of the inertia mass block's movement trip under trajectory overload. Mass blocks are limited by mechanical movement and are difficult to integrate in fuze systems, and is poor in testability. A scheme based on MEMS sensor technology is proposed and designed to arm the fuze. The principle, composition, function of the system, software workflow and the test and verify situation are introduced. This method has a wide scope of use can improve the flexibility of fuze systems and is easy to system integration.

A concept design method for the return of the first sub-stage of a launch vehicle is proposed. It provides a solution for the overall design of a recoverable Launch vehicle. Firstly, a motion model for return of first stage is built. In order to calculate the thrust and its adjustment range, two parameters that named thrust ratio and thrust adjustment factor are defined in the model. Secondly, relation between recovery thrust and left propellant is discussed. A constraint of left propellant is introduced. Finally, a return scheme of a first stage is planned through a simulation example. The method proposed answers such questions as how much propellant should be reserved to realize the return of the first stage, how much thrust should be used, what is the adjustment range of thrust during the return process, the landing point of the stage, the max velocity during the return, and height and velocity before the stage enters the landing phase. The example shows that this method can be used to plan a complete return scheme for the first stage of a launch vehicle.

The low orbit internet constellation represented by "Starlink" is a hot topic in the current development of the aerospace field. Multi-satellite stack technology can significantly improve the utilization rate of fairing space, thereby accelerating the construction speed of low orbit constellations, and is one of the important directions of future multi-satellite launching technology. This article analyzes the requirements and significance of multi-satellite stack technology, summarizes the existing connection forms of multi-satellite stack, and then points out the suitable connection forms for large-scale constellation construction through comparative analysis. The mature connection schemes of multi-satellite stack are interpreted, and the composition principle and technical characteristics of this technology are obtained. Finally, the difficulties and challenges in the stucture design and connection technology of multi-satellite stack are analyzed and prospects are proposed, providing reference for future multi-satellite stack structure design.