In traditional chined waverider design, the adjustment of design profile parameters is complex and the design intuitiveness is insufficient. To address these issues, this paper proposes a chined upper surface design method based on B-spline curves. The design flexibility and convenience are improved by directly adjusting the design profile through control points. The base profile is constructed by means of Bezier curves, the leading edge and lower surface base profile are determined using the osculating cone theory, and the upper surface profile is designed using cubic and quadratic B-spline curves. The reliability of the proposed method is verified by computational fluid dynamics (CFD) methods, and the aerodynamic performance of the chined waverider is analyzed. The results demonstrate that, as the angle of attack gradually increases, the influence of the chined upper surface on aerodynamic characteristics weakens gradually, and the maximum lift-to-drag ratio appears at the angle of attack ranging from 4° to 6°. The proposed method provides a more intuitive profile optimization means for waverider design, which has reference value for engineering design.

The mechanical properties of high-entropy alloys (HEAs) are studied. For this purpose, a simple and precise testing system is established for determining the equation-of-state parameters of HEAs. Based on the principle of wave impedance matching, a test setup is designed using the pressure comparison method to obtain the shock adiabat data of HEA materials. The acquired experimental data is then optimized through adaptive clustering detection. After optimization, the confidence intervals for the slope and intercept of the experimentally determined shock adiabat are narrowed from [1.66293, 2.03332] and [4.01158, 4.38089] to [1.6461, 1.92734] and [4.15248, 4.27542], respectively, and the coefficient of determination (R²) is improved from 0.9687 to 0.9849. The Hugoniot equation-of-state parameters for the HEA are determined as C₂=4.214km/s and λ₂=1.787.The Hugoniot equation of state established in this study is applicable within a pressure range of approximately 5.86-32.77 GPa, and its extrapolation to higher pressure regimes necessitates further experimental validation to guarantee reliability. The results demonstrate that the proposed system achieves high-precision measurement of equation-of-state parameters for high-entropy alloys hrough the combination of data optimization algorithms with experimental design. This work provides critical technical support for the performance assessment and practical application of such materials under dynamic mechanical conditions.

To address the issue of small penetration aperture in traditional shaped charge warheads against underwater single-layer targets,a novel W-shaped shaped charge structure design method based on the inner cone angle α and outer cone angle β is proposed.The influence of liner structure on jet formation and damage effectiveness is studied.The ratio μ of the lengths of the inner and outer sides of the liner is defined a-s a characterization parameter affecting the underwater formation and damage performance of the W-shaped liner.The influence of the ratio μ on the formation and initiation points on the formation and penetration of annular jet are analyzed through numerical simulations.The results indicate that,the annular jet converges excessively toward the axis when μ is 0.22,forming an explosively formed projectile (EFP).When 0<μ<1,the outward expansion trend of the annular jet gradually intensifies,the head-to-tail velocity difference decreases,and the jet stability improves with the increase in μ.When μ>1,the slug at the jet tail is reduced,the jet head expands,the head-to-tail velocity difference increases,and the jet stability significantly decreases under the influence of the external water medium with the increase in μ.Additionally,the increase in the number of initiation points induces necking at the head of the annular jet,which has little impact on penetration and aperture formation under the condition of small standoff distance.The large-area damage of annular jet to the target plate can be achieved by optimizing the combination of the inner and outer cone angles of the liner to adjust the value of μ and the number of initiation points.

To improve the resistance of B₄C/Al composite targets against explosively-formed projectile (EFP) penetration, the surface morphology of ceramic strike face is modified. Seven types of B₄C/Al composite targets featuring different protrusion-array structures on the strike face are examined. The processes of EFPs penetrating into the composite targets at 1.5, 1.7, and 1.9 km/s are simulated using LS-DYNA. The evolutions of the projectile's mass, velocity and kinetic energy during penetration are analyzed. The results indicate that B₄C/Al composite targets with protruded strike-face structures exhibit superior penetration resistance and deceleration capability compared with B₄C/Al flat-faced targets. Among them, the composite target with a pyramidal protrusion array provides the best deceleration performance for the simulated EFP.The R3 semi-cylindrical target demonstrates the best protective performance under normal impact. The penetration direction significantly affects the penetration resistance of anisotropic protrusion-array targets and the sinusoidal-structured target has the optimal protection performance under oblique impact.

The influence of grooved structure on the penetration and damage performance of copper-aluminum/polytetrafluoroethylene (Cu-Al/PTFE) energetic composite liner is investigated.A energetic composite liner with large cone angle (140°) is numerically simulated and experimented,and the damage effect of a pre-grooved energetic composite liner on concrete target is examined.A comparison shows good agreement between the experimental and simulated results.The influences of groove structure parameters such as groove width,depth,and wall thickness ratio on the damage effect of jet are further analyzed.The results show that the groovee structure has an effect on the distribution of jet energy between radial expansion and axial penetration.The smaller widths,shallow depths and narrow spacing of grooves are conducive to the radial hole enlargement,whereas the larger widths,greater depths and wider spacing of grooves enhance energy concentration,thereby increasing the penetration depth.Additionally,the number of grooves and the wall thickness ratio significantly influence the stability of jet and the ability of reactive materials to follow up.In particular,a wall thickness ratio of 1∶1 between the copper and reactive material layers yields favourable jet formation and damage performance.

The penetration tests on three sets of geometrically similar projectiles with scaling ratios of 1/1, 1/2 and 1/3 are carried out to investigate the size effect of penetration depth of projectile into concrete media. A calculation method for penetration depth with the projectile diameter coefficient as a variable is proposed, and a conversion coefficient model that takes into account the scaling ratio is established for penetration depth. The dynamic strain rate of material in the projectile-target contact zone during the penetration processare quantitatively analyzed through numerical simulation, and the values of penetration depth conversion coefficients under different scaling ratios are ultimately determined. The results show that the size effect exists in the dimensionless penetration depth between the prototype projectile and the model projectile, which arises from the difference in the average strain rates of target in the tests with different scaling ratios. The strain rate increases with the increase of penetration velocity and the decrease of projectile diameter, and does not conform to the geometric similarity scaling relationship. The established penetration depth conversion coefficient is correlated with the target strain rate and the scaling ratio. This conversion coefficient not only quantifies the influence of the material strain rate on the size effect, but also clarifies the mechanism of the size effect of penetration depth in concrete media from a mechanistic perspective.

To address the low decision-making efficiency and poor practicality of weapon-target assignment (WTA) in modern air-defense operations,a multi-objective WTA model that comprehensively considers four performance metrics including ammunition consumption,operational cost,total engagement time,and interception benefit is constructed.Practical constraints such as weapon-ammunition compatibility,ammunition inventory,and damage thresholds,etc,are also taken into account to enhance the battlefield applicability of the model.Secondly,a hybrid heuristic algorithm—hybrid ahaotic quantum particle swarm optimization-variable neighborhood search (HCQPSO-VNS) is proposed to solve the proposed WTA model.In the proposed algorithm,a logistic chaotic mapping is employed to improve the quality of the initial population,the quantum particle swarm optimization (QPSO) is utilized for global search; and the variable neighborhood search (VNS) with multiple neighborhood structures is integrated for local optimization to avoid premature convergence.Simulated results demonstrate that the proposed algorithm converges to a high-quality feasible solution within very few iterations.The obtained assignment schemes satisfy the expected lower bounds for damage,weapon-ammunition compatibility,and other constraints,while achieving an effective balance among four performance metrics.Comparative analysis shows that the overall performance of the proposed algorithm outperforms several mainstream algorithms,and can effectively improve the efficiency and scientific rigor of air-defense firepower allocation decisions.Meanwhile,as the problem complexity increases,the proposed algorithm retains high optimization efficiency and acceptable computational load,demonstrating favorable scalability.

In response to the application requirements of inertial navigation systems for quartz flexible accelerometers with a large range and high dynamic flight accuracy, a new structure for the pendulum assembly of quartz flexible accelerometer is proposed to enhance the range and second-order coefficient of accelerometer. A mathematical model of the designed pendulum assembly is established to derive the scale factor of the designed accelerometer. The design range of accelerometer is theoretically calculated based on the load capacity of servo circuit. The optimization method for the second-order coefficient of the accelerometer is analyzed, and an optimization scheme for the second-order coefficient is provided. Through numerical simulations, it is verified that the deflection and stress of the designed pendulum assembly under full-scale conditions meet the design requirements. Experimental results show that the quartz flexible accelerometer achieves a range of 110g and a second-order coefficient better than 5 μg/g², thereby improving the dynamic application capability of quartz flexible accelerometers in inertial navigation systems.

This paper investigates the guidance of missiles striking the maneuvering targets in three-dimensional (3D) space in the presence of model uncertainties, unknown target maneuvers and terminal impact angle constraints. An impact angle control guidance law based on nonsingular fixed-time sliding mode control (NFTSMC) and fuzzy logic is proposed. First, a 3D missile-target relative motion model is established, and the terminal impact angle constraint control is reformulated as a line-of-sight (LOS) angle tracking problem. To overcome the singularity commonly encountered in conventional terminal sliding mode control, a nonsingular fixed-time sliding mode surface (NFTSMS) is constructed, and an auxiliary function is introduced to guarantee singularity-free controller design. In addition, a fuzzy logic system (FLS) is incorporated to online approximate the lumped disturbances induced by target maneuvers and model uncertainties. The fixed-time stability of all signals from the closed-loop system is strictly proved based on Lyapunov stability theory. The simulated results show that the proposed guidance law can achieve the accurate interception of maneuvering targets under different initial conditions. Compared with the existing fixed-time sliding mode guidance strategy, it has significant advantages in suppressing the control command chattering and improving the line-of-sight angle tracking accuracy.

The direction-finding performance of guidance and direction-finding system is limited with a small-aperture array and the array configuration optimization is a key step to improve system performance due to platform resource constraints such as weight,volume,and deployment space.In this paper,the Cramér-Rao bounds (CRBs) for wideband two-dimensional direction-of-arrival (DOA) estimation of both scalar arrays and polarization-sensitive arrays are derived,and a CRB-based performance evaluation and configuration optimization method for small-aperture arrays is proposed.Firstly,the development of wideband DOA estimation and the typical two-dimensional array structures are reviewed,and the wideband signal models based on subband decomposition are established for both scalar arrays and polarization-sensitive arrays.For scalar arrays,a closed-form expression for the CRB of wideband two-dimensional DOA estimation is provided.Subsequently,a general framework and closed-form expression for the CRB of wideband two-dimensional DOA estimation of polarization-sensitive arrays are derived,and a performance evaluation criterion for two-dimensional direction finding with such arrays is established.Finally,A two-dimensional array configuration optimization method based on the derived CRB is proposed by considering the constraints ofguidance system platform on the number of array elements and array aperture.The quantitative optimization of array layout can be achieved by constructing an array configuration optimization set and conducting theoretical performance evaluation.The research results provide theoretical support and technical guidance for the array configuration design and performance evaluation of small-aperture guidance direction-finding systems.