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31 August 2024, Volume 45 Issue 8

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Contents

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2024, 45(8):  0. 

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Collaborative Optimization and Security Control of Source-grid-load-storage of Tank and Armored Vehicle Power System: Architecture Design and Frontier Thinking

YUE Wenbin, NING Gongtao, NI Yongliang, SONG Keling, HUANG Yu, WANG Zhiyuan, LI Yanming

2024, 45(8):  2463-2477.  doi:10.12382/bgxb.2023.0643

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In order to ensure the safety, reliability, high-quality, and efficient operation of tank and armored vehicle power systems in complex environments, the development of on-board power systems characterized by active flexibility, collaborative optimization, and flexible interaction is an important direction for the future generation of fully electric combat vehicles. The source-grid-load-storage collaborative optimization and safety control of tank and armored vehicle power systems with electrification as a characteristic are studied. The necessity and challenges of developing the power systems are elaborated from the aspects of inherent conditions and external driving forces. Then, the core content and key technologies of source-grid-load-storage collaborative optimization and safety control for power systems are introduced from the perspective of architectural design. This includes the active flexible safety control technology used in extreme environments, the multi-timescale optimization and scheduling technology used in normal environments, as well as the flexible dynamic control technology used in scenarios with significant disturbances. Furthermore, in conjunction with the concept of a “resilience” power system, the performance characteristics of power systems based on “resilience” optimization and control when facing extreme or unexpected events are discussed, which can provide a reference for the future development of tank and armored vehicle power systems in China.

Smoke Screen Video Detection and Parameter Extraction Based on Convolutional Neural Network and Spatio-temporal Features

GUO Aiqiang, LI Tianpeng, ZHU Xi, GUAN Zhichao, LI Men, DONG Hongyu, GAO Xinbao

2024, 45(8):  2478-2486.  doi:10.12382/bgxb.2023.0595

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In order to enhance the operational effectiveness of jamming bomb on the battlefield, it is imperative to comprehend the fundamental characteristics and extreme deployment conditions of jamming bomb, and amend the smoke dispersion equation associated with jamming bomb. Nonetheless, given the inherent variability in the transparency and texture of jamming bomb during the operational deployment and its diverse appearance in different environmental contexts, there exists a significant challenge in accurately extracting the smoke's contour and motion features. To address this issue, a hybrid approach based on the convolutional neural networks and the spatiotemporal characteristics of smoke is proposed. The proposed method encompasses five distinct phases: Adjustment of contrast in YUV color space; Implementation of a frame difference method to detect the motion regions within the input video image sequence, employing a well-designed convolutional neural networks architecture to identify potential smoke regions within these motion regions; Utilization of the smoke's spatiotemporal characteristics to further discern potential smoke regions within each candidate area; Adoption of a support vector machine (SVM) classifier which employs the extracted features to classify real smoke regions from non-smoke regions; Extraction of smoke feature parameters. The experimental results show that the proposed model can be used to improve the accuracy of smoke recognition to at least 99.94%. Consequently, it effectively meets the requirements for adjusting the smoke dispersion equation during the operational deployment of jamming bombs, providing substantial support for the prototyping experiments and practical utilization of jamming bomb.

Penetration Effect of Tungsten Alloy Spherical Projectile on CFRP-coated B₄C Ceramics

WANG Yifan, LI Yongpeng, XU Yuxin, LIU Tielei, JIAO Xiaolong, WANG Ruosu

2024, 45(8):  2487-2496.  doi:10.12382/bgxb.2023.1083

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The failure mechanism and protective properties of carbon fiber reinforced composite (CFRP)-coated boron carbide (B₄C) ceramic target plates under the penetration of tungsten alloy spherical projectile are investigated, the protective properties of the composite structure under different D/T, where D represents the projectile diameter, and T represents the ceramic thickness, are experimentally studied and numerically simulated. The residual velocity of projectile after penetrating the target and the damage morphology of target plate are obtained through ballistic impact tests, and the failure characteristics of B₄C ceramics and CFRP at different penetration speeds are analyzed. The numerical simulation model of tungsten alloy spherical projectile penetrating the target plate is established, and the accuracy of the model is verified by reproducing the experiment results. The influence of CFRP on the penetrating effect of tungsten projectile is compared and analyzed. Based on the numerically simulated results, a residual velocity calculation model of tungsten projectile penetrating the target plate is established, and the accuracy of calculation model is verified by the experimental results. The findings indicate that, under the vertical penetration of projectile into the target plate, the CFRP exhibits a circular fracture on the impact surface and a cross-shaped fracture on the back surface. The damage area of CFRP on the back surface is larger than that on the impact surface.With the increases in penetration speed and target thickness, the change amplitude of the damage area of CFRP on the back surface is larger than that on the impact surface. It is found that the anti-penetration performance of CFRP-coated B₄C ceramic target plate is 4.8% higher than that of B₄C ceramic target plate. Compared with the experimental results, the absolute value of relative error computed by the proposed calculation model is less than 15%.

A Review of the Evaluation Methods of Assisting Effectiveness of Exoskeleton Robot and Its Applications

LIU Yali, LU Yanchi, XU Xiaolong, SONG Qiuzhi

2024, 45(8):  2497-2519.  doi:10.12382/bgxb.2023.0637

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Exoskeleton robots have shown promising applications in military, medical and industrial fields. A scientific exoskeleton assisting effectiveness evaluation system is urgently needed to achieve guidance and specification for exoskeleton research and development, product iteration, and practical use. CiteSpace visualized scientific knowledge mapping analysis and data statistics are conducted to comprehensively grasp the existing performance evaluation methods. The current research status of 5 common assisting effectiveness evaluation methods is reviewed in detail, including metabolic cost evaluation, bioelectrical signal evaluation, kinematic and kinetic parameters evaluation, work performance evaluation, and comprehensive evaluation models, and their key indicators and technical limitations are summarized. An outlook on the development trends and research priorities of exoskeleton assisting effectiveness evaluation technology is presented from 4 aspects: evaluation theories deepening and test method, establishment method of targeted candidate evaluation sets, comprehensive evaluation model structure design and index weights assignment method, and multi-scene test method, which has practical significance to improve the exoskeleton testing system and realize technology horizontal comparison.

Afterburning Effect of Thermobaric Explosives in Confined Space

JIANG Xinli, ZHANG Guokai, HE Yong, YAO Jian, WANG Zhen, WU Yuxin, LIU Ju, WANG Mingyang

2024, 45(8):  2520-2530.  doi:10.12382/bgxb.2023.0555

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The explosion of thermobaric explosive has a significant afterburning effect, and itsexplosion in a confined space has multiple destructive effects. However, the coupling effect of multiple damage elements due to afterburning effect and the quantitative analysis of the afterburning enhancement effect are not clear yet. The implosion test of thermobaric explosives and LiF instead of aluminium powder explosive under different dosages is carried out ina large enclosed building, and the temperature, shock wave overpressure, quasi-static pressure and oxygen concentration are tested. The temporal and spatial variation characteristics of various damage elements under implosion conditions are analyzed, and the distribution characteristics of explosion damage elements are determined. The distribution characteristics of explosion damage elements in closed buildings and the influences of aluminium powder afterburning effect on temperature, shock wave overpressure, quasi-static pressure and oxygen concentration are clarified through the comparative test of LiF instead of aluminium powder explosion. The results show that the thermal effect and pressure impact of internal explosion in confined space are significantly enhanced at the corner boundary, and the total specific impulse at the boundary is increased by 2.2-2.5 times. The afterburning effect of aluminium powder can significantly improve the temperature, shock wave overpressure, quasi-static pressure and oxygen consumption.When the dosage reaches 300g, the aluminium powder afterburning leads to the explosion shock wave overpressure peak increased by 1.2 times, the temperature peak increased by 6.4 times, the quasi-static pressure increased by 2.2 times, and the oxygen concentration consumption increased by 2.8 times.

Chaos Driven Quaternion Rotation Three-dimensional Constellation Encryption for WFRFT Communication

YU Haoyang, MENG Qingwei, YUN Yanzhi, WANG Xikang

2024, 45(8):  2531-2541.  doi:10.12382/bgxb.2023.0393

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To address the issues of uneven distribution and limited mapping parameter ranges of existing one-dimensional chaotic mapping sequences, an improved one-dimensional logical sine chaotic mapping is presented. A chaos encrypted multi-parameter weighted-type fractional Fouier transform (MPWFRFT) called chaos driven quaternion rotation three-dimensional (3D) constellation encryption (CQR3DE-MPWFRFT) communication method is proposed to improve the secure transmission performance in the physical layer. Logistic mapping and Sine mapping are coupled together to form a new L-S chaotic mapping. The information that needs to be transmitted is modulated in 3D space. A chaotic key is generated from L-S chaotic mapping to drive quaternions, which rotates and encrypts the generated 3D constellation. The whole digital modulation process is completed after MPWFRFT. The whole system performance is verified through simulation. The simulated results indicate that the proposed L-S chaotic mapping has a larger parameter range and better randomness. The proposed CQR3DE-MPWFRFT method utilizes L-S chaos to drive quaternions, and can achieve the rotational encryption from two-dimensional constellations to 3D constellations which have a larger constellation distance compared to traditional 2D modulation. The bit error rate performance of CQR3DE-MPWFRFT method can be greatly improved. Even if the eavesdropper's key is only 10^-15 different from the correct key, eavesdropping cannot be completed, which helps to improve the transmission security of information in the physical layer.

Adaptive Fractional Order Positive Position Feedback for Vibration Control of Vertical Tail

ZHANG Jiaxuan, LI Bin, NIU Wenchao, LI Kaixiang

2024, 45(8):  2542-2553.  doi:10.12382/bgxb.2023.0570

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Aiming at the deficiencies of the adaptive positive position feedback (APPF) controller in the control efficiency and the fractional order positive position feedback (FOPPF) controller for the small perturbation interval, a fractional order adaptive positive position feedback (FOAPPF) controller is proposed, which aims to enhance control effectiveness while maintaining robustness. The distinct impacts of various parameters on the FOPPF controller are evaluated to derive the optimal parameter range. The sine sweep responses of multiple perturbation models of the system are comprehensively weighted. Additionally, the system's control performance far from the resonance frequency band is considered, leading to the formulation of an objective function for control design incorporating necessary constraints. The FOAPPF controller is designed based on the vertical tail model attaching macro fiber composites (MFC) and its perturbation model. Compared with FOPPF controller, the poles in the closed-loop system of FOAPPF controller are insensitive to the parameter perturbation. Moreover, compared with the APPF controller, the slope of the phase-frequency curve of FOAPPF controller is smooth in the perturbation frequency band, and its control efficiency is less affected by the online estimation error of natural frequency. Various experimental conditions show a significant improvement in the control effectiveness of FOAPPF controller across different perturbation models. Furthermore, the RMS value of the vertical tail buffeting response is reduced by at least 55%, indicating substantial robustness. Therefore, the FOAPPF controller demonstrates the promising potential for active vibration control of vertical tail structures.

Efficient Computational Model and Analysis of Structural Stability of Multi-layered Fiber Optic Cable Package

LI Xiaodong, MENG Lei, ZHOU Ping, YAN Ying

2024, 45(8):  2554-2563.  doi:10.12382/bgxb.2023.0559

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The structural stability of fiber optic cabke package has a significant impact on the service status of fiber optic systems. To address the issues of long computation time and low efficiency of numerical analysis methods like finite element analysis due to strong nonlinearity and more winding layers of fiber optic cable package, an efficient computational model is established to analyze the structural stability of fiber optic cable packages. This model is used to analyze the effects of fiber optic winding patterns and uniformity of wire diameter on package structural stability. The critical values are provided for the wire diameter and uniformity that lead to the instability of fiber optic cable package. It is shown that this model improves the computational efficiency by approximately 100 times without sacrificing the computational accuracy compared to the finite element method. The "consistent residual tension" winding pattern enhances package structural stability. When the deviation of wire diameter exceeds ±3% of the standard wire diameter, the fiber displacement increases sharply, seriously impacting the package structural stability. This study holds significance for real-time analysis and control of multilayer fiber optic winding processes.

A Line Array Camera-based Measurement Method for Dynamic Parameters of Underwater Projectiles and Supercavitation Evolution Process

SUN Jiawei, WAN Gang, GU Jinliang, XU Mingjie, KONG Xiaofang

2024, 45(8):  2564-2572.  doi:10.12382/bgxb.2023.0408

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To address the challenging underwater conditions, poor lighting, and difficulties in capturing and reconstructing the high-speed motion and supercavitation evolution of projectiles, a line array camera-based underwater projectile image acquisition system is designed. The system utilizes the principle of intersection measurement and incorporates a dual line array camera for image acquisition. An algorithm is proposed for underwater high-speed supercavitating target recognition and projectile shape reconstruction. The formulas for calculating the coordinates, attitude angles, and velocity of projectilepassing though a target are derived by using the geometric relationship of supercavitating projectile and the camera calibration data. A water entry experiment of projectiles vertically launched from a 12.7mm smoothbore gun is conducted to validate and analyze the feasibility of the system. Experimental results demonstrate that the system can effectively and rapidly acquire the underwater projectile images, accurately separate and reconstruct the projectile shapes and cavity morphology, and calculate the underwater projectile's motion velocity, attitude angles, and supercavitation parameters. The velocity calculated by the system exhibits an error of less than 1% compared to the velocity obtained from concurrently deployed high-speed cameras, indicating the high reliability and practicality of the system.

Implicit Lyapunov Function-based Variable Gain Super-twisting Sliding Mode Control of an Ammunition Transfer Manipulator

LIN Yubin, HOU Baolin, BAO Dan, ZHAO Wei

2024, 45(8):  2573-2583.  doi:10.12382/bgxb.2023.0642

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To improve the robustness of positioning control of an ammunition transfer manipulator under the influence of load uncertainties during the ammunition transmission process, a novel variable-gain super-twisting sliding mode control method based on implicit Lyapunov function is proposed. A dynamic model of ammunition transfer manipulator system is established, and then the key parameters of friction torque and balance torque in the equations are identified to further reduce the system uncertainty. A variable-gain super-twisting sliding mode control strategy is designed by utilizing the implicit Lyapunov function, and then the global stability of the closed-loop system is proved by the Lyapunov stability theory. The value of the control gains is determined by the system Lyapunov function, which is a differentiable function of the sliding mode variable. Therefore, the proposed control method has the advantage of easy adjustment of control parameters. The experimental results show that the compensations of friction torque and balance torque can shorten the positioning time from 2.659s to 1.157s, which improves the positioning performance of the system. Under different experimental conditions, the proposed control method can effectively suppress the influence of load uncertainties and guarantee the positioning stability of the system.

Construction and Characterization of Weighted Directed Association Network for Remote Detection of Underwater Targets

ZHANG Hongwei, WANG Haiyan, YAN Yongsheng, SHEN Xiaohong

2024, 45(8):  2584-2593.  doi:10.12382/bgxb.2023.0394

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Remote detection of underwater targets is a critical technology in ocean defense systems and has significant applications in both national defense and civilian domains. However, there is currently a lack of effective methods for long-range detection of underwater targets, especially without prior knowledge of the target. To address this issue, a new detection method based on weighted directed association network, is proposed, which represents the target signal detection problem as network topology by mapping the vector acoustic signal into the weighted directed association network. The long-range detection of underwater targets without prior knowledge is achieved through the analysis of network topology characteristics and the feature extraction. The proposed method is validated through the simulated and measured data. Compared with existing narrowband mutual spectrum detection and bubble entropy methods, the proposed method can detect the underwater targets with lower signal-to-noise ratios and achieve the long-range detection without prior knowledge. The proposed method has important practical significance and application prospects and can provide the effective technical support for underwater target detection in ocean defense and civilian fields.

Parameter Optimization Method of Fuzd Setting System Based on Harris Hawks Optimization Algorithm

YUAN Hongwei, LI Haojie, DAI Keren, CHEN Hejuan, ZHANG He

2024, 45(8):  2594-2606.  doi:10.12382/bgxb.2023.0429

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In order to meet the real-time requirements of tank gun ammunition in combat, the fuze must quickly and accurately receive the enemy's distance, azimuth and other information transmitted by the weapon platform, which is very important to improve the effectiveness of combat damage. In response to the challenges faced by fuze in receiving energy and information rapidly and reliably under the constraints of actual weapon platform environment, a mathematical model for the synchronous transmission of energy information in a fuze sharing firing channel setting system is established. This model is characterized by an objective function for minimizing the setting time through the optimization of system design parameters. Additionally, it incorporates the constraints to ensure the reliable reception of energy information even in harsh platform channel conditions, resulting in an optimization model for the system design parameters. The Harris hawk optimization (HHO) algorithm is used to solve the optimal value of the system parameters. The simulated results show that parameter optimization method based on HHO algorithm can be used to obtain the optimal system design parameters. Compared with the system with unoptimized parameters, the time for synchronous transmission of energy information is reduced by 26.4% and the reliable reception ratio of information is increased by 40.4% on average under different channel parameters. Especially in the harsh channel environment where the channel capacitance is greater than 5nF, it can still ensure reliable information reception, the speed and reliability of energy information reception are greatly improved, and the combat effectiveness is optimized. The effectiveness of this method has been verified through laboratory experiments.

Modeling and Analysis of Rudder Nonlinear Control Force for Dual-spin Projectile with Canards

ZHAO Xinxin, SHI Jinguang, WANG Zhongyuan, ZHANG Ning

2024, 45(8):  2607-2616.  doi:10.12382/bgxb.2023.0402

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A dual-spin projectile with canards is ballistically corrected by adjusting the orientation of the forebody roll angle, and establishing an accurate rudder control force model is the key to an in-depth study of its ballistic characteristics and ballistic design. Taking the interference between projectile and each canard into account, the Fourier series is used in the non-rolling frame to transform the periodic effect arising from the change in the orientation of longitudinal symmetry plane of forebody with respect to the plane of complex attack angle, and an accurate rudder control force model is established for this type of projectile flying at large attack angles. The relationships among the structural parameters of canards, the amplitude and phase of complex attack angle and the orientation of forebody roll angle are revealed. The computational fluid dynamics (CFD) numerical method is used to simulate and analyze the rudder control force at different forebody roll angles and complex attack angles. The results show that the rudder control force has strong non-linearity in magnitude and direction, especially at large attack angles, due to the combined influence of the normal forces of a pair of despinning rudder and steering rudder. The proposed model can accurately describe the rudder non-linear control force of dual-spin projectile with canards and the influence of various factors on it, which provides a theoretical basis for the forebody structure design, ballistic characteristics analysis and ballistic design of the projectile.

Modeling and Optimization Method of Kill Chains Based on AGE-MOEA

WAN Silai, WANG Guoxin, MING Zhenjun, LI Chuanhao, YAN Yan, DING Wei, YUAN Ke, WANG Yuqian

2024, 45(8):  2617-2628.  doi:10.12382/bgxb.2023.0566

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A modeling and optimization method of kill chains based on adaptive geometry estimation-based multi-objective evolutionary algorithm (AGE-MOEA ) is proposed for the kill-chains design. Based on the idea of kill chain closure, the OODA cycle theory and the traditional weapon target assignment model, a multi-objective optimization mathematical model of kill chains design is constructed to realize the mathematical representation of kill chains design problem. The proposed model comprehensively considers three kinds of equipment, which are used for reconnaissance, command and attack, respectively, and takes the maximum attack efficiency, minimum weapon consumption and minimum damage threat as the objective functions, and takes the equipment use constraints, kill chain relation constraints and damage threshold constraints as constraint conditions. The algorithm flow of kill chains optimization design based on AGE-MOEA is proposed to solve the multi-objective optimization mathematical model of kill chains design. Through the numerical experiments and the kill chain design experiments in air defense and anti-missile combat scenarios, the results show that the proposed method can simultaneously pursue the optimization of attack efficiency, weapon consumption and damage threat on the premise of ensuring that all kill chains of each target are closed, and obtain a kill chain solution, which can form a distributed lethality. The scientificity of multi-objective optimization mathematical model of kill chains design, the effectiveness of AGE-MOEA algorithm in solving kill chains design problems and the feasibility of kill chain design method in practical military operations are verified.

Experimental and Numerical Study on Navigation Characteristics of Waterjet Propulsion Amphibian Vehicle

LU Hang, LIU Haoran, CHEN Tairan, HUANG Biao, WANG Guoyu, CHEN Huiyan

2024, 45(8):  2629-2645.  doi:10.12382/bgxb.2023.0620

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Special amphibious vehicles with the ability to maneuver on land, sail on water, and operate in the water-land interface zone are an important part of future multi-domain collaborative systems. The navigation characteristics of a waterjet propulsion amphibious vehicle under weak constraints are experimentally and numerically investigated. A numerical calculation method for the integrated control of waterjet propulsor and amphibious vehicles is established. The hydrodynamic performance of waterjet propulsion amphibious vehicle is studied. And the accuracy of the numerical calculation method is fully verified. The navigation characteristics of the amphibious vehicle under the conditions of towing and constrained self-propulsion at the designed speed are compared and analyzed. Compared with the conventional “ship-pump” integrated research, the research results on the mutual influence of waterjet propulsor and surface vehicle have been enriched from the perspective of amphibious vehicle. Under constrained self-propelled condition, the resistance of vehicle is increased by 17.6% compared to the resistance without waterjet propulsor. The change of vehicle attitude caused by the operation of waterjet propulsor is the main factor causing the increase of resistance. Compared with the condition of towing, the extension length of virtual length increases from -0.864 X/L (X is the length from the center of gravity of the vehicle, L is the total length of amphibious vehicle) to -1.513 X/L under the constrained self-propelled condition. At the same time, the wave height and divergent wave area of the chicken wake significantly increase from 0.037 H/L (H is the wave height)to 0.061 H/L, which leads to the increase of the energy loss near the wake field.

Three-dimensional Adaptive Fixed-time Multi-missile Cooperative Guidance Law

YU Hang, LI Qingyu, DAI Keren, LI Haojie, ZOU Yao, ZHANG He

2024, 45(8):  2646-2657.  doi:10.12382/bgxb.2023.0640

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An adaptive fixed-time cooperative guidance law is proposed for multiple missiles simultaneously attacking a maneuvering target in three-dimensional space. A 3-D missile-target dynamics model is established, and the adaptive guidance law are designed based on the line of sight (LOS) direction and its vertical direction. This ensures that the remaining flight time and normal velocity converge consistently within a fixed time. The adaptive guidance law are employed to track the motion parameters of maneuvering targets, thus enhancing the stability of multiple missile system and its strike accuracy against the maneuvering targets. The convergence conditions of the multiple missile system are improved, and the designed guidance law possess the capability to constrain the attack time. Saturated functions are introduced into the guidance law to avoid system oscillations caused by the sign function. The effectiveness of the proposed fixed-time cooperative guidance law and its robustness against communication topology switches are validated through simulation experiment. The experimental results indicate that, compared to the guidance law designed in the reference literatures, the proposed guidance law exhibit rapid system convergence and high accuracy.

A Configuration Synthesis Method of Reconfigurable and Decoupled Wheel-legged Mechanical Leg

PAN Wuxing, LI Ruiqin

2024, 45(8):  2658-2666.  doi:10.12382/bgxb.2023.0398

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A set of fully-decoupled reconfigurable wheel-legged hybrid mechanical leg configurations are synthesized based on the screw theory and the motion bifurcation principle of reconfigurable mechanism. According to the degree of freedom requirements of wheel-leg mode, the wheel-leg transformation mechanism is analyzed, and then five kinds of main motion limbs are synthesized and selected. The principle and scheme of constraint limb arrangement are proposed based on the wheel-leg transformation mechanism, and the constraint limbs are obtained based on the screw theory. According to the geometric conditions of the main motion limbs and the constraint limbs, the axis transformation of the kinematic pair and the decomposition and combination of the kinematic pair are carried out, and 134 constraint limbs are finally obtained. Based on the concept of motion decoupling of parallel mechanism, the selection condition of driving pair is derived, and the position of driving pair in each constraint limb is determined. The correctness of the mechanism synthesis method is verified by an example. The synthesized mechanical leg realizes the wheel-leg mode switching based on constraint singularity, which reduces the time consumption required for configuration transformation and makes mode switching more efficient. In addition, there is no need to lock the joints related to leg mode motion during wheel motion due to the existence of structural constraints, which reduces energy consumption and driving control difficulty.

Influence of Weight Parameters on Oscillation Characteristics of Supercavitating Vehicle

GUO Kaixin, HUANG Chuang, YAN Feng, GU Jianxiao, LI Daijin

2024, 45(8):  2667-2677.  doi:10.12382/bgxb.2023.0489

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The influence of weight parameters on the oscillation characteristics of supercavitation vehicle is studied. A simulation model of the coupling of supercavitation flow field and rigid body motion is established by combining VOF multiphase flow model, realizable k-ε turbulence model, Schnerr-Sauer cavitation model and the rigid body motion equations. The proposed model is validated by comparing the simulated results with the published test results. The influences of mass and centroid position on the oscillation characteristics of supercavitation vehicle are quantitatively summarized by simulating and studying its free motion characteristics. The research findings reveal that the simulated results of the proposed simulation model are consistent with the experimental data, showing a 1/4 cycle phase difference between pitch and yaw angles. The oscillation period is approximately 0.0795 seconds with a deviation not exceeding 3.38%, indicating the reliability of the proposed simulation model. The free motion of supercavitating vehicle exhibits “cone-like” dynamic oscillation characteristics; With the decrease of the mass of the vehicle, the oscillation amplitude of attitude angle is basically unchanged, and the oscillation period of the trajectory gradually decreases. The oscillation period is decreased by 13.26% when the mass of the vehicle is decreased by 33.33%. The oscillation amplitude of attitude angle is gradually increased and the oscillation period of trajectory is decreased by decreasing the distance of mass center away from the cavitator. The oscillation period is decreased by 14.29% when the mass center distance is decreased by 25%.

Numerical Simulation of Magnetic Interference Parameter Identification of AUV Based on L-SHADE Agorithm

ZHOU Guohua, LI Linfeng, WU Kena, LIU Yuelin, XIA Shuai

2024, 45(8):  2678-2687.  doi:10.12382/bgxb.2023.0599

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The autonomous underwater vehicle (AUV) magnetic measurement platform can be used for marine geomagnetic field measurement, underwater magnetic target detection and identification, etc. The AUV magnetic measurement platform has broad application prospects. However, at present, the magnetic interference compensation technology of AUV carrier is not mature, which restricts the magnetic measurement accuracy of underwater vehicle. Based on the basic principle of anti-magnetic interference of magnetic measurement platform, a numerical simulation method based on success history-based adaptive differential evolution with linear population size reduction (L-SHADE) algorithm is proposed for the identification of magnetization interference parameters of AUV carrier. A hybrid model of magnetic dipole and ellipsoid of rotation is used to equivalently simulate the magnetic interference of AUV carrier. Multiple groups of magnetic measurement data are obtained through simulated navigation, a magnetic interference parameter identification model is established accordingly, and L-SHADE algorithm is used to solve the problem. The propagation law of the magnetic measuring accuracy of magnetic measurement platform with the errors of magnetic sensor, platform attitude and heading is studied through quantitative analysis of numerical simulation experiments. When the measuring accuracy of magnetic sensor is 10nT, the attitude measuring accuracy is 0.01°, and the course measuring accuracy is 0.1°, the measuring error can be less than 100nT. The anti-jamming test of the designed AUV magnetic measurement platform shows that the maximum relative error of the total geomagnetic field is 1.07%.

Safety Optimal Tracking Control Algorithm and Robot Arm Simulation

CHEN Wenjie, CUI Xiaohong, WANG Binrui

2024, 45(8):  2688-2697.  doi:10.12382/bgxb.2023.0576

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A safety optimal tracking control algorithm based on reinforcement learning is proposed to ensure that safety-critical systems operate within a safe area and maintain optimal performance. Both the safety and optimality of the system are considered by adding a control barrier function in the evaluation function. The relative dominance of the control barrier function over the evaluation function is specified by adding damping coefficients to the control barrier function. The idea of reinforcement learning is introduced to realize the safety optimal tracking control of the system with unknown system dynamics. It has been proven that the tracking control system can achieve optimality and stability within a safe region. The effectiveness of the proposed algorithm is verified through simulation of a two-link planar manipulator. The experimental results show that the end position of the manipulator is controlled within a safe range, while also achieving optimal performance during stabilization. The simulated results demonstrate that the proposed algorithm can achieve safe and optimal tracking control effects.

Design of Event Trigger-based Vibration Control for Active Suspension System

PANG Hui, WANG Mingxiang, WANG Lei, ZHENG Lizhe

2024, 45(8):  2698-2711.  doi:10.12382/bgxb.2023.0590

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To improve the ride smoothness and safety of vehicles, an intelligent vibration controller based on event trigger (ET) and long short-term memory (LSTM) neural network is devised for automotive active suspension systems characterized by input dead zone and saturation. On the basis of building a quarter-car active suspension model, an appropriate ET controller is proposed, which effectively mitigates the communication bottlenecks and avoids the inherent Zeno phenomenon of controllers, thus enhancing their stability and reliability. A LSTM neural network is introduced to further improve the intelligence and adaptability of controller. A radial basis function neural network is utilized to simulate and generate the required response data for training LSTM neural network and compensate for input dead zone and saturation, making the vertical acceleration of the active suspension system get closer to 0m/s² and thus improve the vehicle ride comfort. The applicability and effectiveness of the designed controller are verified by numerical simulation. The research findings indicate that the controller can effectively enhance the dynamic performance of active suspension system under diverse operating conditions.

Thermal Demagnetization Characteristics of Nd-Fe-B Used in Eddy Current Recoil Mechanism of Artillery

SUN Zhengping, YANG Guolai, LI Lei, WANG Liqun

2024, 45(8):  2712-2727.  doi:10.12382/bgxb.2023.0616

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Permanent magnet eddy current recoil brake is an innovative design in the field of efficient control of recoil resistance of artillery. In the application scenario of artillery with high energy consumption density and relatively closed working environment, there is a serious temperature rise in the eddy current recoil brake. High temperature will lead to the decrease in the magnetic properties of Nd-Fe-B materials and then affect the recoil characteristics. At present, the thermal demagnetization process of Nd-Fe-B is not clear and lacks theoretical expression. In order to grasp the thermal demagnetization characteristics of Nd-Fe-B, the demagnetization process of NdFeB at different temperatures is quantitatively analyzed from the perspective of microscopic magnetic moment heating motionbased on the micromagnetic simulation method, and the demagnetization curve of macroscopic Nd-Fe-B is obtained. In order to use the demagnetization curve for better guiding the engineering design, the J-A model is used to describe the demagnetization behavior of Nd-Fe-B, and the experimental verification is carried out. The magneto-thermal coupling numerical calculation of demagnetization and resistance degradation of Nd-Fe-B is carried out based on the traditional residual magnetic flux density model and the J-A model. By comparing with the experimental results of the prototype, it is found that the J-A model is more accurate in describing the magnetic properties of Nd-Fe-B. The working performance of recoil brake under different working temperatures and chamber pressures is calculated, and the demagnetization characteristics of Nd-Fe-B and the damping characteristics of recoil brake under the temperature field are analyzed. The results show that the maximum demagnetization of Nd-Fe-B is 0.351T under the worst working conditions, and the maximum recoil displacement of recoil brake is 1108mm, which provides a theoretical reference for the design of eddy current recoil brake.

Characteristic Analysis of Damping Valve in Hydro-pneumatic Suspension of Tracked Vehicle Based on Bonding-diagram

NIE Wei, HE Hongwen, LEI Qiangshun, WAN Yiqiang

2024, 45(8):  2728-2736.  doi:10.12382/bgxb.2023.0654

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To optimize the damping characteristics of vehicle suspension, a parametric model for the damping characteristics of damping valve in hydro-pneumatic suspension is established based on the bonding diagram method. According to the dfferent working modes of damping valve before and after opening and closing during compression stroke and during recovery stroke, the throttling form of damping valve under different working conditions is analyzed, and a damping characteristic model for the compression and recovery strokes of damping valve are established by combining the knowledge of fluid dynamics. The influences of structural parameters on the compression stroke, recovery stroke and flow rate of valve opening point are analyzed by simulation. A flow test bench is designed to verify the simulation results of damping valve characteristics. The results show that the characteristic model of damping valve established by the bonding diagram method can accurately calculate the characteristics of damping valve, the diameters of orifices 2 and 3 in the spool are decreased to reduce the opening speed of damping valve, the diameters of orifices 1 and 4 are adjusted to regulate the damping force accordingly without affecting the opening speed, and the diameter of orifice 6 only affects the damping force on the recovery stroke.

A Robust Beamforming Algorithm for Sparse Array Based on Atomic Norm Minimization

LÜ Yan, CAO Fei, JIN Wei, HE Chuan, YANG Jian, ZHANG Hui

2024, 45(8):  2737-2748.  doi:10.12382/bgxb.2023.0618

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Aiming at the performance degradation of the beamforming algorithm when some mismatches are present in the signal model. A robust beamforming algorithm based on atomic norm minimization (ANM) is proposed to improve the beamforming performance of sparse array during the mismatch of signal model. The proposed algorithm is used to construct an ANM-based noise reduction model and transform it into an equivalent semi-definite programming problem according to the covariance matrix structure of sparse array. Meanwhile, the dual problem of this model is derived to improve the computational efficiency, and the received data and covariance matrix of the array after noise reduction are obtained. The spatial spectrum is proved to be unambiguous based on the structural properties of a coprime array, and the directions of arrival of the incident signals are obtained directly by using the multiple signal classification algorithm for the resulting covariance matrix. The received data of a uniform linear array with the same aperture as the coprime array is obtained using the virtual filling technique, and the array output is ultimately obtained. Simulated results verify the feasibility and accuracy of the proposed algorithm, which improves the output signal to interference plus noise ratio by at least 1.5dB compared to the other tested algorithms.

Prescribed Performance-based Lateral Channel Control Method of Underactuated Hypersonic Vehicle

WANG Xiaofang, XU Jiaqi

2024, 45(8):  2749-2760.  doi:10.12382/bgxb.2023.0544

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A control method combining the prescribed performance function and dynamic surface control is designed for the underactuated problem caused by the lateral channel of hypersonic vehicle only through aileron control. The lateral underactuated system is transformed into a roll-yaw cascade control system. For the rolling rotor circuit, the limiting of sideslip angle command is regarded as the saturation problem of control input. A prescribed performance function is designed, and a control strategy is proposed based on the dynamic surface control theory, which realizes the active control of the tracking speed, transient tracking error and stable tracking accuracy of a bank angle. Then, aiming at the requirement that the sideslip angle needs to be stabilized in a given range, based on the limiting sideslip angle instruction, a prescribed performance function of yaw sub-loop is designed, which theoretically ensures that the sideslip angle meets the stabilization range requirements and can achieve the specified tracking accuracy at the required tracking speed. Finally, the stability of the lateral attitude controller is proved based on the Lyapunov stability principle. The simulated results show that the proposed control method can be used to make the bank angle reach the specified tracking accuracy at the required tracking speed and the transient tracking error satisfies the given boundary; the sideslip angle satisfies the given limited range; and the controller has good robustness.

A UAV Trajectory Optimization Method Based on RRT-Dubins

WANG Dongzhen, ZHANG Yue, ZHAO Yu, HUANG Daqing

2024, 45(8):  2761-2773.  doi:10.12382/bgxb.2023.0611

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A unmanned aerial vehicle (UAV) trajectory optimization method based on the rapidly-exploring random trees (RRT) algorithm and Dubins curves is proposed to address the problem of UAV trajectory planning in multi-obstacle environments. The initial and final poses, turning radius, and trajectory length, and first-order smoothness constraint of UAV are considered in the trajectory planning. The RRT algorithm and a pruning optimization method based on a greedy algorithm are utilized to plan the feasible discrete waypoints that satisfy the obstacle avoidance requirements in a two-dimensional task space. Multiple Dubins curves are employed to smoothly connect the waypoints. A multi-constraint trajectory optimization mathematical model is established based on the UAV's initial and final poses, and the constraints related to the UAV's performance and obstacles. The particle swarm optimization (PSO) algorithm is employed to determine the curve types and optimize the poses at the curve connections and the curve radii, thereby obtaining the shortest trajectory. Simulated results demonstrate that the proposed method reduces the average trajectory length by 11.48% in various scenarios with different numbers of obstacles and varying initial and final positions, while satisfying the UAV's kinematic constraints and avoiding obstacles compared to other methods.

Assessment of Protective Equipment Performance and Weapon Lethality Based on Human Anatomical Structure

JIA Yining, WEN Yaoke, DONG Fangdong, QIN Bin, LI Zixuan, ZHENG Hao

2024, 45(8):  2774-2783.  doi:10.12382/bgxb.2023.0540

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Considering the complexity of the human body structure, the human voxel model with 402 anatomical structures based on the Chinese Visible Human dataset was proposed to assess the performance of the protective equipment and the effectiveness of the killing element when it impacts on the protected body; An algorithm for assessing the performance of protective equipment and the lethal effectiveness of weapons based on anatomical structures was proposed. A module for assessing the performance of protective equipment and the lethality of weapons have been developed in the vulnerability software. Obtained killing characteristic quantity changes when 5.8×42mm rifle bullet impacts NIJ Ⅲ protection at different velocity; Obtained the relationship between different head-helmet gaps and human survival rate when 9mm pistol bullet impacts the MICH helmet. The results of the study show that the lethality of a 5.8×42mm rifle bullet impacting on the human body at 850m/s was 80% (protected) and 4% (unprotected). The lethality of the bullet improves with target velocity (lethality rate >50% at a speed of 950m/s); The survival rate is 40% when a 9mm pistol bullet impacts the head (without a helmet), and 84% when wearing a helmet with 25mm head-helmet interval. Therefore, a wider head-helmet interval provides more effective head protection. The study can provide the basis for the assessment of the effectiveness of typical killing element (bullet and fragment) and the performance of protective equipment, as well as a reference for the weapon design and the protective equipment development.

Carrier Frequency Estimation of Radar Signal Based on Fuzzy Solution Library and Chinese Remainder Theorem

LI Bowen, QIU Zhaoyang, LIU Yifei, CAO Bin, SUN Minhong

2024, 45(8):  2784-2792.  doi:10.12382/bgxb.2023.0521

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Radar reconnaissance receiver is required to have ultra-wideband receiving ability to obtain the high probability of interception. Because of the hardware limitations, the conventional receiver based on the Nyquist sampling theorem is difficult to achieve instantaneous ultra-wideband receiving. The under-sampling theory based on the Chinese remainder theorem (CRT) provides a feasible approach for ultra-wideband receiving. However, the traditional frequency estimation method for CRT requires a coprime among the modulus values, and the number of sampled points must be the greatest common divisor of the modulus. To overcome these limitations, a fuzzy solution library is constructed. A precise carrier frequency estimation method of radar signal is proposed based on the fuzzy solution library and CRT, which uses the one-to-one mapping relationship between remainder and signal frequency. The proposed method has no need to solve the congruence equation system, and relaxes the requirements for the sampling frequency and the number of sampling points. Finally, the effectiveness of the proposed method is verified through simulation experiments. Compared with the traditional CRT algorithms, the proposed method has no necessity to change the modulus when estimating the carrier frequencies of different radar signals, which is more convenient for engineering applications. Meanwhile, the proposed method provides good estimation accuracy and noise resistance.

Analysis of Walking Vibration and Stability of High Strut Landing Gear

DU Xiaoqiong, LI Bin, LUO Linyin, LIU Mujun, YANG Rong

2024, 45(8):  2793-2805.  doi:10.12382/bgxb.2023.0629

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In order to improve the gear walk instability of high strut landing gear equipped with carbon ceramic brake discs, the rule of gear walk is analyzed thoroughly. The gear walk mechanism is explained. The braking torque with negative slope caused by the friction characteristics of the carbon ceramic brake disc can introduce negative damping to the longitudinal system of the landing gear, which causes the divergence of walking vibration. The effects of the brake torque parameters, the structural parameters of landing gear and the initial velocity of aircraft on gear walk are studied. Finally, a gear walk control strategy for reducing the braking pressure with the relative angular velocity of brake stators and rotors is proposed. The result shows that the decrease in the absolute value of negative slope of brake disc friction coefficient and the braking pressure, as well as the increase in the longitudinal stiffness and damping of strut will all contribute to the stability of gear walk. The stable gear walk can be achieved at any initial velocity of aircraft by increasing the minimum friction coefficient of brake disc to 0.186. The dropping slope of braking pressure is closely related to the initial velocity of aircraft. The simulated results of aircraft braking from 144km/h show that a 24.7% dropping in braking pressure can lead to the convergence of unstable gear walk and a 77.23% reduction in the longitudinal acceleration peak of wheel axle.

A Time-invariant Sparse Model and a Deep Unrolling Network for Target Detection of Passive Radar

ZHAO Zhixin, CAO Yulong, CHEN Yuanshuai, ZHOU Huilin, WANG Yuhao

2024, 45(8):  2806-2816.  doi:10.12382/bgxb.2023.0579

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In recent years, the target detection method based on sparse feature extraction has become a research hotspot in radar field. However, due to the uncontrolled transmitted waveform of orthogonal frequency division multiplexing(OFDM)-based passive radar, the sparse model will change with the unknown transmitted waveform, resulting in a large amount of calculation and more manual intervention for the corresponding target detection method. On the other hand, it is difficult to detect target echo because it is often covered by strong clutter such as direct-path signal. In this context, a time-invariant sparse model is proposed by using the waveform characteristic of the OFDM-based passive radar and the channel frequency response at the pilot position. Then, a realization method of intelligent passive radar target detection based on the deep unrolling network is firstly studied by replacing each iteration process of the sparse model solution with a layer of neural network. Simulated and measured results show that the proposed method has similar performance to the traditional clutter suppression method in target detection, but it has lower computational complexity, and does not need to manually design the solving parameters such as sparse matrix of sparse model.

Aerial Infrared Image Target Recognition Algorithm Based on Rotation Equivariant Convolution

XIAO Feng, LU Hao, ZHANG Wenjuan, HUANG Shujuan, JIAO Yulin, LU Zhaoting, LI Zhaoshan

2024, 45(8):  2817-2827.  doi:10.12382/bgxb.2023.0503

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In order to improve the rotation robustness of the traditional UAV infrared target recognition algorithm to the input image, an infrared image target recognition algorithm with rotation equivariant is proposed. An infrared image is expanded into a three-channel image to enrich the details and edge information of the input image by referring to the visible-light three-channel structure. The standard rotation equivariant convolution FBL and rotational residual FSP modules are designed and implemented based on the rotation equivariant convolution, which can highly retain the rotation characteristics of the image, so that the FC-YOLOv5 model is robust to the rotation of the image and the target in the image; The SE attention mechanism is added to learn the importance of each channel adaptively, and the channel contribution in the feature map is weighted according to the needs of the task, so as to extract the important feature information and suppress the unimportant feature information. The performance of the model is verified on APOPV data set and SAS data set, and the benchmark model YOLOv5s and the models YOLOv8s and NanoDet used in common lightweight target recognition tasks are used as the control models. The experimental results show that the mean average precision of the proposed algorithm can be improved by 2%-4% compared to the benchmark model, and when the input image has different rotation angles, the FC-YOLOv5 can recognize more rotating targets with fewer recognition errors than those of the control model.

Study on the Cook-off Characteristics of B/KNO₃ Ignition Charge

WU Junying, SHANG Yiping, ZHENG Fude, DU Haojie, YAO Yule, LI Junjian, CHEN Lang

2024, 45(8):  2828-2836.  doi:10.12382/bgxb.2023.0657

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The cook-off test devices for multi-point temperature measuring are established to study the thermal safety of B/KNO₃ ignition charge. The multi-point temperature measuring and cook-off tests of B/KNO₃ ignition charge under the conditions of different heating rates and charge densities are made to obtain the accurate ignition time of ignition charge and the temperature curves of different monitoring points during the cook-off tests. A numerical calculation model of B/KNO₃ ignition charge for the cook-off test is established. The self-thermal decomposition reaction and phase transition heat absorption of ignition charge are considered in the calculation model. Then, the model is used to simulate the cook-off process of B/KNO₃ ignition charge under the conditions of different heating rates and charge densities. The thermal and kinetic parameters of B/KNO₃ ignition charge are calibrated by comparing with the experimental results. The results show that the pre-exponential factor of B/KNO₃ ignition charge is 7.763×10¹³s^-1, and its activation energy is 2.0787×10⁵J/mol; with the decrease in the heating rate, the ignition delay time increases gradually, the ignition area moves to the center gradually, and the ignition ambient temperature decreases gradually. When the change in charge density is not significant, the ignition characteristics of ignition charge do not differ much.

Influence of Combustor Configuration on Rotating Detonation Characteristics of Kerosene Pre-combustion Cracking Gas

HAN Jiaxiang, BAI Qiaodong, QIU Han, ZHENG Quan, WENG Chunsheng

2024, 45(8):  2837-2850.  doi:10.12382/bgxb.2023.0491

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The width and outlet blockage ratio of rotating detonation combustion chamber are changed under the condition of fixed incoming flow. The effect of combustor configuration on the rotating detonation characteristics of kerosene pre-combustion cracking gas and air was experimentally investigated. The experimental results show that suitable combustor width and outlet width can promote stable self-sustaining propagation of rotating detonation wave (RDW). When the width of combustor is 20mm or 26mm and the width of combustor outlet is 4~8mm, the kerosene pre-combustion cracking gas and air can be successfully detonated and can propagate stably. The propagation velocity and stability of RDW are improved by increasing the width of combustor. With the increase in outlet blockage ratio, the RDW propagation mode experiences stable single rotating detonation wave (SRDW) mode, intermittent single rotating detonation wave (ISRDW) mode and two-co rotating detonation waves (TCORDW) mode. The blockage ratio can be increased to improve the intensity of reflected shock wave at the end of combustor and promote the generation of multiple wave heads. RDW propagation velocity and pressure increase first and then decrease with the increase in blockage ratio.

Particle Emission Characteristics of Heavy Diesel Engine During Low-temperature Star-up and Warm-up

CAO Zhikun, WU Han, ZHANG Shuchun, ZHANG Guixian, CHANG Jiang, LI Xiangrong

2024, 45(8):  2851-2862.  doi:10.12382/bgxb.2023.0625

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The high soot particle emission during the start-up process of heavy diesel engine at low-temperature has a serious effect on the start-up efficiency. The start-up performance of diesel engine at low-temperature is influenced by the coolant and lubricating oil temperature. To reveal the soot particle emission characteristics of diesel engine during start-up process at low temperature, the in-cylinder pressures, and soot and particle emissions at different initial coolant and lubricating oil temperature conditions during start-up and warm-up are measured by single-cylinder engine bench test. The results show that the soot emission of the engine is the highest in the early stage of low-temperature start-up. With the increase of coolant and lubricating oil temperatures during warm-up, the soot emission gradually decreases, the number concentration of aggregated particles is reduced, the number concentration of nucleation mode particles is increased, and the total particle number concentration is dominated by nucleation mode particles. Increasing the initial coolant and lubricating oil temperatures under cold start-up condition reduces the soot emission during the start-up process, the number concentration, particle size, surface area and mass of nucleation mode particles decrease, the number concentration of aggregated particles decreases, and the particle surface area and mass are increased with the increase in large-sized aggregated particles. The soot and particle emissions during the start-up process can be reducedd by increasing the heating capacity of the heating pot at low temperature to increase the initial temperatures of coolant and lubricating oil, which improves the start-up efficiency and reduces environmental pollution.