Abstract:Naval battlefield is one of the important battlefields in military confrontation. The naval battle space is involved with air, water, underwater and coastal land, etc., and combat resources are enormous in quantity and are diverse from each other in capability. With the continuous development of unmanned system technology, the cross-domain unmanned swarm will become an important force in future maritime warfare. Taking the maritime cross-domain unmanned swarm as a research object, firstly, the paper combs out the related concepts and evolution process of cross-domain operations, and defines the connotation of cross-domain unmanned swarm. And then the development trend and current situation of the US military single-domain unmanned swarm project are described, and the main contents of the recent cross-domain unmanned swarm exercise are analyzed. Finally, the existing research results in the key technologies for the unmanned swarms are refined and summarized, and the challenges facing the development of cross-domain unmanned swarms are pointed out. Simultaneously, the future development trend of cross-domain unmanned swarms is given.

Abstract:Cooperative planning of multiple unmanned aerial vehicles (UAVs) swarm is a hotspot research issue in the field of UAVs autonomous control. A novel task allocation method is proposed for multi-UAV reconnaissance based on unsupervised learning discrete pigeon-inspired optimization. Firstly, a model of UAV is established by Dubins path. Secondly, a simplified sensor model and a reconnaissance target model are given, and a task allocation model of multi-UAV and index function of performance are established. The reconnaissance targets are grouped flexibly by the unsupervised learning method, and then the task allocation model is solved by using the improved discrete pigeon-inspired optimization strategy, effectively solving the unbalanced task load between UAV and improving the efficiency of UAV swarm reconnaissance. Finally, the method proposed in this paper is valid through the simulation comparison experiments and the three dimensional situational scene simulation platform experiments.

Abstract:The algorithm for dynamic target allocation of cross-domain unmanned swarm in an imprecise information environment is proposed in this paper. Firstly,The paper delineats a realistic scenario of cross-domain drone swarm warfare and conducting an analysis of the inherent uncertainties in target positioning and impact points of firepower units due to the imprecision of detection information. Secondly, a probability model for target pre-allocation is developed based on this analysis, followed by the design of an enhanced discrete multi-objective particle swarm algorithm for solution purposes. Additionally, to address real-time emergence of new targets in the combat environment, a contract net-based target re-allocation algorithm, employing market mechanisms, is proposed to enable the real-time updating of target allocation schemes. Finally, the efficacy of the proposed algorithms is validated through experimental simulations. This research offers a comprehensive solution for the dynamic target allocation challenge encountered in cross-domain unmanned swarm operating in an imprecise information environment, with the potential to enhance the effectiveness and efficiency of unmanned swarm warfare.

Abstract:In view of the evaluation problem of cooperative operational capability of UAV Swarm based on information network, the information entropy which is used to measure the degree of information uncertainty is utilized for quantifying the node capability of the network and the weight of the combat side, and a dynamic evaluation network of information flow is constructed. Through the shortest circuit algorithm with node degree limitation, a possible parallel combat ring of the network, and a minimum entropy of the network calculated by three kinds of computing methods, i.e. serial, parallel and mixed structures, are found out, realizing the quantitative evaluation of the cooperative combat action of UAV Swarm. The effectiveness of this evaluation method is verified by evaluating the capability of unmanned aerial vehicle (UAV) Swarm maritime containment and control operations. Based on the principle of maximum effectiveness, some suggestions on the cooperative strategy and operational use of UAV Swarm are given.

Abstract:This paper focuses on the architecture of manned-unmanned cooperative combat system, so as to meet the needs of fast-paced and large-scale in the future. Taking battle management as the underlying logic, the architecture is constructed. Firstly, the battle management basic theory is sorted out, and the “mission-capability” and “capability-resource” attribute mapping is established. Then, the manned-unmanned activities are designed based on the combat management level, using the U.S. Department of Defense architecture framework view model. And the timing and logic are sorted out by the functional attributes. Exploring the “nesting” phenomenon of combat management contained in modeling, the barrier of military researchers’ understanding of combat operations can be reduced. Meanwhile, the theoretical and simulation support can be improved.

Abstract:As a flame stabilizer of scramjet engine, the cavity has attracted much attention. The interaction between cavity shear layer and background waves affects the performance of cavity flame stabilizer. To deeply analyze the influence of background shock wave system on the flow in the cavity, a cavity with an aspect ratio of 13.3 is designed. The leading-edge shock wave of the cavity model and the wall interation shock wave on the upper wall of the wind tunnel are used as the background waves. The interaction between the background waves and the cavity shear layer is carried out in a Ma=2 direct-connected wind tunnel. The high-speed schlieren system is used to capture the transient flow field, focusing on the dynamic characteristics of the background waves and the cavity shear layer. The main coherent structures in the flow field are studied by the snapshot proper orthogonal decomposition of the schlieren sequences. The frequency characteristics of the flow field are analyzed by fast Fourier transform and continuous wavelet transform. The results show that with the interaction between the background waves and the shear layer, the shock-wave structure produces large-scale oscillation and the flow structure in the cavity produces small-scale pulsation. With the Fourier transform analysis of the shock wave position, it is found that the dominant frequency of the shock wave oscillation is mainly concentrated in the range of 100Hz-500Hz. With〓the spatial Fourier transform analysis of the schlieren image, it is found that the flow field pulsation below 5 kHz is mainly caused by shock-wave oscillation, and the flow field pulsation above 5 kHz is mainly caused by the flow structure in the cavity.

Abstract:Gas film damping can effectively suppress multi stage vibration of aeroengine blades which has the advantages of simple structure and small added mass. This paper focuses on the flat plate structure with gas film damping, establishes the vibration model of a flat plate with gas film damping, derives the expression of vibration suppression rate under the influence of the temperature; Using the finite element method, study the effects on the vibration suppression rate of gas film damping structures under uniform and non-uniform temperature fields. The results is:①Flat plates with air film damping have a high vibration suppression rates under uniform and non-uniform temperature fields; Under this two temperature fields, when the temperature field of the flat plate increases from 20℃ to 600℃, the increase in vibration suppression rate of gas film damping structure is less than 10%; ②When the gas temperature inside the gas film increases from 20℃ to 600℃, the increase in vibration suppression rate of gas film damping structure is less than 4%, the variation of gas temperature in the gas film has less effect on the vibration suppression rate of a flat plate with gas film damping, can suitable for the different temperature environments; ③When the vibration of the flat plate is in the second torsional vibration mode, the vibration suppression effect of the gas film damping structure decreases sharply, the vibration of the absorbing sheet will intensify the vibration of the flat plate, the phenomenon may occur under different temperature gradient.

Abstract:In order to evaluate the capacity of the safe return channel of offensive operations in the time and space of military aviation warfare, this paper proposes the node confluence control cellular automata model (MRCA model). According to the configuration of the safe return passage in air attack operations, focus on the operational characteristics of nodes at the intersection of the passage, quantify the safe spacing of nodes into the confluence rules, and study the maximum flow of the passage before and after the nodes under different acceptable spacing conditions. And based on the traffic operation characteristics of the channel before and after the node, the minimum risk channel entry time window is established to move forward the time node of capacity balance regulation, eliminate the potential conflict of the fighter at the node in the strategic management and pre tactical management, and achieve the maximum traffic capacity. The simulation results show that the channel capacity increases with the decrease of the interval after the node confluence, and the maximum is 102 frames/h. Within the time window that the minimum risk channel can enter, the MRCA model is used to dynamically control the aircraft at the decision circle, which can ensure the safe confluence of nodes and maximize the flow.

Abstract:In order to make a case-based reasoning technology even more effective in the high-level anti-missile deployment at the terminal section, this paper studies construction and use of case library in the high-level anti-missile deployment at the final stage. Firstly, the organization and the construction of the case database are studied, i.e. the expression of cases, the organizational structure of the case database and the construction process of the case database. Secondly, the application of the case database is studied, i.e. core content of which retrieval is done and matching of similar cases is made, and the case analysis are given. Finally, the problem of streamlining the case library is studied. The research content is involved with most of the problems in the process of building and using the case library.

Abstract:The rapid and accurate detection of surface defects in materials has become an important objective across various research domains. To enhance detection efficiency and realize lightweight equipment,this paper proposes a target detection optimization algorithm based on YOLOv5, adding DyHead detection head to enhance the detection accuracy of the model by fusing multiple attention mechanisms; replacing the aLRPLoss loss function to reduce the hyperparameter adjustment work and optimize the training process; propose C3-Faster based on FasterNet to replace the C3 module in the network to improve the model detection performance and reduce the model size with the idea of PConv; finally add the lightweight upsampling operator CARAFE to expand the model perceptual field and improve the detection effect on targets of different sizes. The experimental results show that the improved YOLOv5 model improves the overall average accuracy by 4.174%, reduces the parameter volume by 11.25%, reduces the computational complexity by 13.75%, and reduces the weight volume by 10.72% on the steel surface defect dataset compared with the original model, and the detection performance is also higher than that of SSD, RetinaNet, FCOS, YOLOv3, and YOLOv4 and other mainstream target detection algorithms, which have high application value in industrial detection.

Abstract:At present, when the time-domain discontinuous Galerkin (DGTD) method is utilizedfor solving the electromagnetic propagation problem in various media, Maxwell's equations of constitutive relation of ordinary media are usually considered. Aimed at the problems thatelectromagnet in Tellegen media with non-reciprocity constitutive relation is very complex in propagation, and few researchers care to ask about something,a matrix discrete scheme of DGTD system is derived for Tellegen medium, and the time-domain propagation characteristics of plane waves in Tellegen medium are accurately simulated based on the constitutive relation of Tellegen medium.The proposed algorithm is utilized for calculating the layered space model of air and Tellegenmedium, andanalyzing the influence of Tellegen medium on electromagnetic polarization deflection angles. Simultaneously, in view ofTellegen media with different electromagnetic parameters, the electric field deflection angles of reflected and transmitted waves are calculated, and the results calculated by the DGTD scheme are compared with the literature ［1］and the analytical solutions. And the effectiveness and feasibility of the proposed method are verified.

Abstract:Under condition of complex conditions, this test is made, and two campus scenes are selected for field being at low-altitude wireless channel measurement with 2.4 GHz frequency. Multi-path amplitude values of 1 200 groups and 1 200 groups of channels are collected respectively. The corresponding root-mean-square time delay extension and Rice factor of the two small-scale fading characteristics are analyzed with statistical methods, and the fitting is made up. The test results show that the average root-mean-square delay spread of the two scenarios is 255 ns and 1 429 ns respectively, and the average Rice K factor is 3.8 dB and 0.32 dB respectively, and the ratio of the former Rice K factor being greater than 0 dB is 58.68%, indicating that the Rice channel is the main channel in this environment. The proportion of the latter being greater than 0 dB is 10.16%, indicating that Rayleigh channel is the main channel in this environment. The fitting results show that the root mean square delay extension is a Gamma fitting, and the Rice K factor is a normal fitting, and the probability density distribution functions of the two characteristics are obtained.

Abstract:To improve the dispersion of carbon fiber in carbon fiber reinforced concrete, using redispersible polymer latex powder and short cut carbon fibers for composite modification of concrete, two batches of 18 (2×9) groups of polymer latex powder-carbon fiber composite modified concrete (PMCFRC) were designed based on the L9(43) orthogonal test table for the slump, 28 d compressive strength and fiber dispersion. The first batch of orthogonal tested investigated the effects of water-cement ratio, polymer admixture and carbon fiber admixture on the performance of PMCFRC. The second batch of orthogonal tested investigated the effects of dispersant type, dispersant admixture and water-reducing agent admixture on the performance of PMCFRC, obtained the basic parameters of the slump, compressive strength and resistivity of PMCFRC, and used the extreme difference and ANOVA methods respectively, the primary and secondary order of each factor was studied to analyze whether their effects were significant or not, based on which the optimal mix ratio of PMCFRC was found. The results show that in the first batch of orthogonal tests, for the slump, resistivity and resistivity coefficient of variation, the amount of carbon fiber admixture is significant factor; for 28 d compressive strength, the water-cement ratio is significant factor; in the second batch of orthogonal tests, for slump and 28 d compressive strength, the amount of water-reducing agent admixture is significant factor; for resistivity and resistivity coefficient of variation, the amount of dispersant admixture is significant factor. The optimum ratio of PMCFRC is 0.49 water/cement ratio, 12%polymer, 0.3% carbon fiber, 34% sand rate, 0.4% hydroxyethyl cellulose as dispersant, 1.2% water reducing agent and 0.3% defoamer.