To study the characteristics of continuous water entry and exit trajectories of a trans-media vehicle, a high-speed ballistic test platform is built, and the experimental model with a built-in measuring system is designed. An unsteady numerical simulation model is developed to solve the coupled flow field and vehicle motions. The motion law and hydrodynamic characteristics of the vehicle's continuous water entry and exit trajectories are studied and validated by experimental results. The results show that the proposed trans-media vehicle realizes a continuous ballistic process of water entry, leveling and water exit. The trajectory is parabola-like, with a maximum entry depth of 0.9 m. The continuous ballistic movement of the trans-media vehicle can be divided into three stages: the planing stage of water entry, the supercavitating stage with a double-sided tail-slapping motion, and the water exit stage with a single-sided tail-slapping motion. The vehicle exhibits pulse oscillation in terms of hydrodynamics, and hydrodynamic characteristics in its aft body are formed by the cone, cylinder and tail-skirt sections. The combination of a preset rudder angle and tail-skirt can enhance the stability of the trans-media vehicle during continuous water entry and exit.

In order to solve the problem of transmedia ejection separation of missile carrier with elastic adapter, based on the fractional areas-volume obstacle representation (FAVOUR) method, a multi-physical field coupling model for missile separation from the carrier near the free surface is established by using the RNG k-ε turbulence model and VOF function. The numerical simulation of the water entry process of the cylinder is carried out, and the calculated results are consistent with the experimental data, which verifies the rationality of the numerical model. The ejection and separation processes of the missile in trough and crest environments and at different initial pitch angles and initial velocities of water exit are numerically simulated, and the effects of initial pitch angle, water exit velocity and position above the water surface on the submarine-launched missile separated from the carrier are obtained. Considering the pitch angle of the missile at the moment of separation from the launch tube at the wave crest and trough positions, the optimal initial pitch angle is 3.24° based on the criterion that the pitch angle of the missile reaches 0° at the separation time at the wave trough position. The simulation method and results are of referential significance for engineering applications.

To solve the problems of insufficient maneuverability and difficulties in engineering applications that are commonly seen in existing underactuated hypersonic vehicle control strategies, an active disturbance rejection/robust control system with new underactuated control strategies is proposed. Firstly, an underactuated control strategy based on channel cascade is presented an important feature is that the yaw channel acts as the inner loop of the roll channel in the new strategy, and the introduction of the ±1.5° legal range of sideslip angle also improves the command tracking speed of the roll angle. Then, the control law is constructed by the combination of active disturbance rejection control (ADRC) and robust control theory. It is not only suitable for non-minimum phase systems with overload feedback/underactuation, but also reduces model parameters dependence in ADRC as well as order reduction difficulty in robust control, thus broadening the controller's application in engineering. Finally, 1 000 times Monte Carlo simulations are carried out on the hypersonic vehicle model with ±20% random perturbation in parameters, and the results show that the proposed strategy can improve the response speed of the roll channel while ensuring the sideslip angle does not cross the boundary. In addition, the control system also has good robustness when confronted with model perturbation and compound interference.

Unmanned tracked vehicles often navigate challenging terrain, and incorporating road types as priori information for tasks such as suspension control, automatic gear decision, and path planning can enhance their performance. However, methods based on single-class features have limitations in accuracy and environmental adaptability. To overcome this, a road-type identification method based on fusion features is proposed, combining deep image features with the statistical features of vertical acceleration in time, frequency, and power spectral density domains. Machine learning classification algorithms are used to identify the road types. Compared to using single class of features, the proposed method using fusion features enriches image features and vertical acceleration features, and improves the accuracy and environmental adaptability. The response speed of the method based on fusion features is similar to that of the image-based methods. Five machine learning classification algorithms are compared. The results show that support vector machine and random forest are the most accurate and fastest classification algorithms, achieving over 90% accuracy with a speed of 14 frames per second.

In order to address the problem of inadequate intensity of the shock wave within the launch canister during its working process, the numerical approach is combined with the dynamic mesh adaptation method to study the generation mechanism of the initial shock wave within the canister and the flow phenomena involved in the technique of cover opening by gas detonation shock waves. First, the experimental results are comparatively analyzed to verify the accuracy of the proposed numerical approach and the reliability of the dynamic mesh refinement or unrefinement of the characteristics of the flow field of interest, such as the shock wave front and contact discontinuity. On that basis, the flat rear cover (primitive design) is taken as an example to expound on the evolution mechanism of the shock wave within the canister, which helps deepen the understanding of the working mechanism behind this technique. Then, the impact of the dome-shaped rear cover on the formation of shock waves within the canister is analyzed. The research results indicate that compared with the flat rear cover, the dome-shaped one can change the angle of collision between the air flow and the side wall at the canister tail, thus slowing down the formation of the turbulence area at this position, which significantly increases the initial shock wave intensity within the canister and increases the peak overpressure exerted on the front cover by around 48%. The findings of this study is of theoretical significance and engineering value to the overall launch canister design.

In the process of gun firing, the inner diameter of the barrel increases by several microns under the action of heat, chemistry and force, which is the main reason for the termination of barrel life. Therefore, it is of great significance to study the change of material properties of the inner bore surface to reveal the barrel life mechanism. The microstructure, thickness and mechanical properties of the inner bore surface materials at different parts of the barrel were obtained by microanalysis of the 155 mm barrel that has reached its life end. Through the analysis of barrel temperature gradient and ablation simulation experiment, the degradation mechanism of the bore surface material and its relationship with projectile firing number were revealed. The results showed that: the hardened layer was formed on the surface of the inner bore under the action of gunpowder gas in the early barrel life; the thickness of the hardened layer was related to the temperature and action time of gunpowder gas; barrel ablation and wear occur on the surface of the hardened layer; the strength of the hardened layer was twice as high as that of the barrel at room temperature, and the strength decreased rapidly at high temperatures, resulting in the increase of the inner barrel diameter under rotating band friction and airflow scouring.

To optimize the mechanism of a single-degree-of-freedom linear-motion setback arming device of a fuze, the effect of the spring preload on the dynamic response characteristics of the inertial unit under different friction conditions was studied. The rigid body dynamics theory and ADAMS rigid body dynamics simulation software were used to study the effect of friction which exists due to the preload of a spring on the locked component on the dynamic response characteristics of the setback arming pin during launch and drop. Through theoretical calculations, the displacement response and velocity response of the setback arming pin under a variety of impact overloads were obtained. The results showed that the frictional retardation effect of the locked component on the setback arming pin contributes to the improvement of the drop safety, and that its effect on the arming performance of the setback arming device during launch is limited. By optimizing the preload force of the spring on the locked component and/or the friction coefficient between the locked component and the setback arming pin, the drop safety of the fuze setback arming device can be improved.

With the development of operational requirements and information technology, all kinds of information projectiles with the functions such as reconnaissance and positioning, precision attack, blockade and jamming have been born. The exertion of their effectiveness usually requires that the missile borne functional devices/components, missile body structure and materials can resist various high overload effects. The anti-high overload technology has become one of the main bottleneck technologies restricting the rapid development of shell informatization and intelligence. This paper combs the development process of the anti-high overload problem of information projectiles, and expounds its essential connotation. The key anti-high overload technologies such as overload environment modeling and measurement, anti-overload structure and materials, anti-high overload test are summarized. This paper puts forward the anti-high overload design idea with functional protection as the core goal, defines the anti-high overload design process of information projectiles. The anti-high overload method of “body strength reinforcement, support deformation and energy absorption, structural member damage transfer and intersection of cutting-edge technologies” proposed in this paper has achieved good results in engineering practice, and provides some reference for the anti-high overload design of information projectiles, rockets and missiles with high overload characteristics.

In order to evaluate the reliability of critical weapon components in high overload environments, a new technology of high overload environment simulation based on the rigid projectile impacting the honeycomb structure was proposed. The acceleration, velocity, displacement response characteristics and dynamic behaviors were studied with the light gas gun experiment. The difference of overload response time histories in the process of the projectile impacting the honeycomb structure under different high impact velocities was analyzed. The results showed that: crushing is a highly localized mechanical behavior, which firstly happened at the top of the honeycomb structure and then spread to the bottom as the projective moved; the compression process of the honeycomb structure subjected to projectile impact can be divided into three stages: initial impact, steady compression and compression to densification, which corresponds to the response characteristics of acceleration, velocity and displacement curves of the projectile; the velocity curve of initial impact stage showed an obvious ladder-shaped decline, resulting from the periodic traveling of stress waves in the projectile; all deceleration curves obtained from the three experiments had a similar peak at the initial stage of each experiment; the lasting time of the steady compression stage decreased with the increase of the initial velocity of the projectile, but the overload peak of the densification stage showed an opposite trend.

A three-dimensional unsteady gas-solid two-phase flow model is proposed to investigate the distribution and stacking characteristics of propellant pellets during the ignition and flame-spreading processes of a single modular charge in the uni-modular charge. Numerical simulations are carried out under different initial conditions at the filling positions of modular cartridges, in which cylindrical pellets are constructed by the multi-element method. The numerical results obtained by the discrete element method (DEM) indicate good agreement with the experimental results, and that the cylindrical particle model is more accurate than the spherical particle model. The simulation results suggest that: when the modular cartridge's initial loading location is 10 mm, 40 mm, 70 mm, and 100 mm from the primer, the pellets are finally distributed on the outside of the right end of the cartridge, showing horizontal and sloped stacking in turn; the axial length of horizontal stacking is reduced from 293.3 mm to 203.8 mm, and the angle of the sloped stacking decreases from 22.01° to 19.82° when the distance between the initial loading position of the modular cartridge and the primer increases from 10 mm to 100 mm; in other words, as the modular cartridge moves to the right, the starting point of horizontal stacking moves to the right, and the axial length decreases linearly; however, the axial length of sloped stacking is almost unchanged, and the slope becomes flat.

The temperature field distribution and evolution inside the mold play a crucial role in determining the casting quality of melt-cast explosive processes. A fast prediction model is developed based on a B-spline neural network for the transient temperature field in a melt-cast explosive process with a water/oil bath. The model is created by first obtaining temperature evolution data samples under different processing conditions through orthogonal numerical experiments. The B-spline neural network is then trained on these data samples to establish a prediction model that represents the relationship between temperature-control parameters and the temperature field inside the grain. This model enables rapid and accurate prediction of the temperature field and solidification front, providing an efficient prediction method for parameter optimization and online control of melt-cast explosive processes. This study serves as a valuable reference for predicting other physical fields in the intelligent development of similar processes in the future.

The silver acetylide-silver nitrate loading technology is an important means to simulate the structural response of intense pulsed X-ray. Pulsed laser initiation is different from the traditional method of initiation by light-induced high pressure. Its advantage lies in the enhanced operating controllability, the implementation of special-shaped load and the timeliness of simultaneous loading. The laser initiation mechanism is analyzed, the laser initiation platform and the properties of silver acetylide-silver nitrate material are introduced, and then the laser initiation experiment is carried out according to the light absorption characteristics of light-sensitive explosives. The initiation thresholds of laser with wavelengths of 193 nm/266 nm/532 nm/1 064 nm are respectively obtained, namely, 5.07 mJ/mm², 6.77 mJ/mm², 7.21 mJ/mm² and 10.61 mJ/mm², and the complete initiation process is verified by detonation velocity. The generation of elements in the reaction process is characterized by radiation spectroscopy. This work can provide technical support for the study of pulsed laser initiation process and mechanism, explosion load law, and the loading technology of using light-sensitive explosives to simulate X-ray structural response.

This study aims to address the problem of electrostatic deposition in aircraft by exploring the electrification voltage of typical materials. The focus is on understanding the change in electrification voltage after collisions between typical materials and air particles at different collision angles and speeds. This research approach involves a combination of simulation tests and analysis, with the goal of understanding the influence of collision angle and speed of air particles on the electrification of typical materials as well as preliminarily unveiling the change law of electrification voltage of certain materials. The results show that the electrification voltage of the typical material increases approximately linearly with an increase in collision angle and speed. The collision speed affects the contact area and mode, while the collision angle affects the proportion of different modes in the contact area, both of which impact the change in electrification voltage of typical materials.

The permanent magnet DC torque motor is widely used in weapons and equipment field. In order to solve the high-frequency fluctuations of the induced voltage and current of the permanent magnet DC torque motor for missiles, based on the mechanism of high-frequency fluctuations, an optimization design method combining virtual-slot design and optimized brush assembly was proposed for the motor to meet the requirements of high-frequency fluctuation performance index. The virtual-slot can increase the number of reversing elements and decrease the number of turns of elements, thus reducing the reversing current. V-shaped grooves were added to the inner wall of the commutator and the rotor forming process was optimized to facilitate rotor production. The brush assembly optimization includes: brush frame structure optimization, spring leaf optimization, brush head material optimization and optimization of brush breaking-in technique to ensure the coplanarity, pressure consistency and wear reduction of the brush. The optimized motor was simulated and tested experimentally. The results showed that: the proposed optimization design method can effectively suppress the high-frequency fluctuations; the peak-to-peak value of the induced voltage fluctuation of the motor after optimization was reduced by 75.23%, and the peak-to-peak value of the current fluctuation was reduced by 76.77%, allowing the motor to meet the design requirements.

In order to investigate the blast resistance of reinforced concrete slabs strengthened with polyisocyanate oxazodone (POZD) coated corrugated steel, contact explosion tests were conducted on reinforced concrete slabs strengthened with corrugated steel and reinforced concrete slabs strengthened with POZD coated corrugated steel, and the damage characteristics were compared and analyzed. Finite element simulations were performed with LS-DYNA software to study the failure mode and failure characteristics. The influence of the damage effect of charge mass was analyzed. The failure mechanism of the proposed structure was revealed from the perspective of stress wave propagation. The test and numerical results showed that there were four failure modes for reinforced concrete slabs strengthened with POZD coated corrugated steel (The front of the structure produces a crater; the front blasting surface of the structure is cratered, the back blasting surface concrete is spalled and the POZD coated corrugated steel bulge deformation; penetration failure of concrete slab, serious bulging deformation of POZD coated corrugated steel; the entire structure was destroyed throughout), and that coating POZD on the back face (explosion receiving face) of the structure can enhance explosion resistance performance. The findings of this study can provide the basis for practical engineering application and protection engineering.

To deal with the difficulty of underwater artificial target detection and tracking via three-dimensional (3D) imaging sonar, a combined geometric feature-based underwater 3D target detection and tracking method is proposed. The algorithm uses distribution information such as the intensity and depth of the sonar image, and the background difference method to extract the kernel function according to the changes in the energy of the sonar image before and after the target appears. Besides, the detection and tracking of the artificial target using three-dimensional mapping instead of two-dimensional mapping is realized by correlating combined geometric features including the Hu invariant moment, target centroid and target distance of the previous and subsequent frame images on the basis of the correlation matching of the two-dimensional sonar image. The data processing results of the lake test show that the algorithm improves tracking performance by about 7.15%, and consumes about 60% less time than the traditional method, which verifies the effectiveness of the algorithm.

An acoustic field model in the form of probability density function is established to solve the problem of model mismatch in shallow water. The Bayesian localization model with the state vector of an acoustic source as a posteriori probability is designed to achieve the purpose of exchanging time for space by iteration and realize the localization of a moving target by a single hydrophone. The grid histogram filtering algorithm is proposed to convert analytical integral into numerical summation and improve efficiency of the algorithm. The SWellex-96 experimental results show that the relative error of depth localization can be controlled at 12.04% and the relative error of distance localization at 6.47% within a depth of 200 m and a distance of 10 km. The proosed method can be used to detect targets in shallow water with concealed low-energy consumption weapon platform.

To solve the tracking control problem of disturbed nonlinear multi-agent system, a fixed-time integral sliding mode control method is proposed based on dynamic event triggering mechanism. A new integral sliding mode surface is designed based on relative state information, the distributed control protocol is developed, and dynamic variable and dynamic event triggering mechanism are constructed on the basis of the measurement error and the sliding mode surface. It can be proved that the appropriate selection of control parameters can drive the multi-agent system to achieve trajectory tracking within a fixed time under the dynamic event triggering mechanism with Zeno behavior avoided. The proposed control scheme can effectively suppress the influence of system disturbance and reduce the consumption of communication and computing resources of the multi-agent system, and meanwhile, avoid the dependence of the convergence time on the initial states of the system. The simulation results demonstrate that the proposed dynamic event triggering controller allows the multi-agent system to achieve the tracking control in fixed time and reduce the triggering frequency to save resources, which is more suitable for practical applications.

To increase communication distance, enlarge signal coverage area, and suppress interference in ground unmanned equipment cluster communication, a new method based on circular array is proposed. By calibrating through channel amplitude-phase consistency, determining signal direction with the MUSIC algorithm, and completing digital beamforming with the Capon algorithm, the method can effectively extract useful signals, suppress noise and interference. Simulation results show that the method can form multiple high-gain beams in the 360° azimuth plane, enable cluster distribution, increase communication distance, and nullify interference. This improves the anti-interference capability of ground unmanned equipment cluster networking communication in the space domain, increasing signal coverage effectively. The research provides a useful reference for beamforming and interference suppression in ground unmanned equipment cluster networking.

The electronic warfare capability of the detected target seriously affects the detection and identification performance of the ground-based air surveillance radar. To address the anti-jamming problem of the air surveillance radar, an anti-jamming waveform design method based on reinforcement learning is proposed. From the perspective of game theory, the reinforcement learning method is used to establish a dynamic confrontation model between radar and target jamming, calculate the state and action value of all parties in the game. The strategy iteration method is employed to generate the optimal strategy, and the time domain waveform is synthesized based on the phase iteration method. The simulation results shows that: when using the radar transmitted signal designed by the proposed method, compared with linear frequency-modulated signals and frequency-agile signals, the signal-to-interference-noise ratio is increased by 6.39 dB and 1.12 dB respectively; when the total signal power is 11 W, compared with the frequency-agile signal, the target detection probability is increased by 5%, meaning that the designed signal can improve the anti-interception performance of radar signals while achieving anti-jamming at low power.

There has been a large number of studies on combat task assignment. However, only a few of them have focused on army force efficiency. This work attempts to address the problem of general combat task assignment from the standpoint of army force utilization. First, the army force is described using single units and compound units in a standardized manner. Second, resource demand analysis is performed and potential resources needed for each task are listed. A mapping relationship is established between the resource and the army force. Then, we formulate the task combination problem and the force dividing code to computational functions mathematically, and introduce the multi-objective optimization method and genetic algorithm to find the optimum task assignment solution. The method is validated using a landing battle example, and the experimental results demonstrate the effectiveness and efficiency of the proposed method.

In order to address the problems existing in dynamic jamming resource allocation, based on the jamming mechanism and tactical principles of miniature air-launched decoy (MALD), a dynamic allocation method of jamming resources for MALD to counter the netted radar system, which is more relevant to the battlefield and has better timeliness, is proposed. Firstly, a threat assessment method based on the ICRITIC variable weights theory is used to determine the dynamic threat matrix of the netted radars. Then, combined with the MALD's active decoy jamming mode and based on the matching degree, the relevant indexes affecting the jamming effect are analyzed, and the jamming effectiveness matrix is constructed. Finally, the objective model of resource optimization is established based on the optimal jamming efficiency, and the improved particle swarm optimization algorithm is adopted to solve the resource optimization problem. The simulation results show that the proposed optimization method can achieve jamming resource allocation in a more rational way and better conforms to the actural operational situation of MALD. Compared with the traditional methods, the computational efficiency and the accuracy of the optimal solution have more remarkable advantages.

In recent years, the increasing military need for accurate identification of camouflaged objects has brought camouflaged object segmentation (COS) technology into existence. COS is more difficult than traditional object segmentation because of the high “integration” of camouflaged objects with the background. In order to segment the camouflaged objects more accurately, we first construct a complete military camouflaged object dataset (MiCOD), and then propose a human vision system-based camouflaged object segmentation network called COSNet. COSNet consists of three parts: featrue extraction module, focus and magnification module, and multi-scale feature fusion module. The focus and magnification module consists of two key serial modules, namely, the key point focus module and the receptive field magnification module. The key point focus module reduces the false alarm rate by simulating the observation process with high human attention, while the receptive field magnification module increases the observation range to improve the segmentation accuracy by imitating the human visual receptive field mechanism. As for the loss function, key point weighted perceptual loss is designed based on the focus and magnification module, which is more suitable for the recognition of camouflaged objects. A large number of quantitative and qualitative experiments on MiCOD demonstrate that COSNet achieves optimal results in eight evaluation metrics and significantly improves the segmentation accuracy. When simulating real battlefield environment, Sen_mean is 0.622, Spe_mean is 0.670, and the missed detection rate and false alarm rate are lower compared to other algorithms.

The bearings-only target tracking is a classic problem in the reserach on target tracking. Focusing on the problem of non-Gaussian heavy-tailed distributed noise in the model of target tracking, this paper proposes a new Kalman filter algorithm. Firstly, the hierarchical Gaussian model is established to approximate the unknown process noise and measurement noise of the non-Gaussian heavy-tailed distributed system. Next, the variational Bayesian inference is used to learn Mixture Probability to solve the problem of the filter's performance degradation caused by the uncertainty of Mixture Probability, so as to improve the robustness of the filter. At the same time, for the nonlinearity of the bearings-only target tracking model, Modified Gain Kalman filter is used to reduce the influence of nonlinearity on the observation equation. The numerical simulations have verified that the proposed filter has better estimation accuracy and robustness than EKF, UKF and the variational Bayesian Kalman filters PEKF-Vb and VBEKF. The estimation accuracy of the proposed algorithm VBMGEKF is improved by 69.31%, 58.08%, 127.84% and 9.36%.

To study the propagation mechanism of short fatigue cracks, a method is proposed to measure the displacement field, strain field, and plastic zone of the short crack tip of plastic metal materials under high-frequency resonant loading using microscope Digital Image Correlation (micro-DIC). And the evolution law of the displacement field, strain field, and plastic zone are studied. First, short crack images of the specimen under maximum resonant loading during fatigue crack growth (FCG) are collected by a microscope camera system. Second, data of the displacement field and strain field at the crack tip region are obtained using the DIC method. Third, the coordinates of the crack tip during short crack propagation are obtained by the virtual extensometer along with the displacement field evolution data. Then, based on the von Mises yield criterion and strain field data, evolution law of the size of the plastic zone is studied and compared with the Irwin model. Last, grain size distribution on the crack tip of 316 stainless steel, a typical plastic metal material, is measured by EBSD technology. The evolution law of displacement and strain along the grain scale in the short crack tip region under high-frequency resonant loading is further studied. The research results show that the proposed method can successfully obtain the micron-scale deformation field evolution data of short cracks, providing experimental and theoretical support for further examination of short fatigue cracks and fatigue life prediction of plastic metal materials under high-frequency resonant loading.

Solids often break into fragments (fragmentation) in response to rapid loading. Research on the fragmentation process is thus of great significance to engineering applications and national defense. Key parameters that affect the size of the fragments include loading rate, material strength and toughness, and fracture process. The nonlinear power-law cohesive fracture relationship is used to describe the fracture process of ductile materialsand the coupling process of fracture and unloading wave propagation is analyzed. The theoretical model provides the fracture time, unloading wave propagation distance, and fragment size for different cohesive fracture paths. The finite element model is used to simulate the fragmentation process of ductile rings expanding at a high velocity, to exhibit the effects of loading rate and different damage models on the fragmentation process. The results show that the unloading wave propagation distance and the average size of fragments both increase with the power exponent k. It is further found that among the numerous power-law nonlinear cohesive fracture paths, the material fails at the fastest rate with the power index k=0.5, which well describes the cohesive fracture process in the fracture zone.

The dynamic shear performance parameters of materials are the important basis for the design of missiles, rockets and armor protection systems. However, there are still problems in the stress uniformity and force state of existing tensile shear specimens, which affect the reliability of test results. Five kinds of tensile shear specimens were compared and analyzed by numerical simulations. In order to solve the existing problems, a new type of tensile shear specimen was designed. The stress distribution of the new specimen is uniform for both quasi-static and dynamic loading conditions, and the stress state is close to pure shear, which is suitable for the accurate testing of shear mechanical properties of materials in large ranges of strain rate and strain. Compared with the test results of double shear specimens (DSS) under compressive loading, it was found that the stress-strain curves were in good agreement, and the new specimen had a longer plastic flow stage. Moreover, numerical simulations were performed to study the deformation and fracture processes of the TC4 titanium alloy specimen, and good consistency was observed between the simulation results and the images taken by the high-speed camera. Therefore, the validity of the specimen design and numerical simulation results is further verified.

A body moving in space needs to do circular swing along three orthogonal directions respectively during the measurement of its triaxial moment of inertia. To reduce the number of azimuth adjustment, a coollaborative proportional method for measuring the triaxial moment of inertia based on vibration compound pendulum and torsion pendulum is proposed. The equipment structure is described, and the full-parameter calculation formula and approximate calculation formula of the proposed method are given. Error analysis is done to this method and a comparison is made with the torsion pendulum method. Simulators are used as the measurement object, and the proposed method is experimentally studied. The experimental results indicate that: the computational results of the two formulas are basically the same when J_z/J_y is less than 1.02; when J_z/J_y is greater than 1.02, only the full-parameter calculation formula can be used, which can also solve the problem of triaxial measurement of the moment of inertia of winged flying bodies; the proposed method and the collaborative difference method previously developed constitute the complete measurement system, which can meet the requirements of certain types of revolving body and heteromorphic body with wings for the triaxial measurement of moment of inertia.

A DOA estimation algorithm based on a natural logarithm compound function approximating l₀ norm is proposed to address the issues of slow convergence and low accuracy of existing compressed-sensing-based DOA estimation algorithms. We transform the problem of solving the l₀ norm into an optimization problem of approximating the l₀ norm by using a natural logarithm compound function. The Newton iteration method is employed to obtain the iteration expression of the natural logarithm compound function (for approximating l₀ norm).The optimal solution of Newton iteration is obtained through inside and outside double-loop iteration, where the outside loop controls the magnitude of function approximation factor σ, and the inside loop solves the Newton iteration expression using the steepest descent method. The optimal solution of the approximate l₀ norm is obtained after finite iterations, and the estimated value of DOA can be obtained. Simulation results show that the proposed algorithm achieves effective DOA estimation under the condition of a single snapshot, and outperforms the existing smoothened l₀ norm algorithm and its improved algorithms in terms of speed and accuracy.

The emergence of 5th generation mobile networks (5G) has provided unprecedented data transmission rates and support for massive data connections. However, traditional orthogonal access technologies cannot guarantee efficient resource utilization. As a type of Non-Orthogonal Multiple Access, Sparse Code Multiple Access (SCMA) technology ensures the reliable transmission of massive user information through effective allocation of resource blocks. The design of the codebook plays a vital role in the efficacy of SCMA technology. In response to limited error rate reduction in traditional codebook design methods, this paper proposes the Eisenstein Integer Optimization (EIO) method. This method constructs the mother constellation on the resource block using Eisenstein Integer (EI) and incorporates the concept of subset segmentation of trellis coded modulation (TCM). Simulation results indicate that, under identical conditions, EIO codebooks offer a lower bit error rate than Huawei codebooks, traditional Eisenstein codebooks, and TCM codebooks. This study provides a feasible codebook design method for SCMA technology.