军事领域细粒度识别技术与应用

战争的信息化程度不断加深对军事侦察提出了更高要求.军事目标识别作为军事侦察的主要任务之一,需要能够处理细粒度军事目标,为人员提供更加详细的目标信息.但传统的粗粒度目标识别方法无法得到目标的细粒度信息.因此,如何识别细粒度目标成为目前军事侦察亟需解决的问题.针对该问题,本文结合军事领域的实际需求,对细粒度识别技术的发展现...     

节矩法测量火炮身管弯曲度的数学模型

用解析的方法建立了节矩法测量火炮身管弯曲度的数学模型,讨论了模型的可解性。并验证了模型的正确性。     

Blast resistance evaluation of urban utility tunnel reinforced with BFRP bars

To improve corrosion-resistance of shallow-buried concrete urban utility tunnels(UUTs),basalt fiber reinforced polymer(BFRP)bars are applied to reinforce UUTs.As the UUT must have excellent survival capability under accidental explosions,a shallow-buried BFRP bars reinforced UUT(BBRU)was designed and constructed.Repetitive blast experiments were carried out on this BBRU.Dynamic responses,damage evolutions and failure styles of the BBRU under repetitive explosions were revealed.The tunnel roof is the most vulnerable component and longitudinal cracks develop along the tunnel.When the scaled distance is larger than 1.10 m/kg1/3,no cracks are observed in the experiments.When the BBRU is severely damaged,there are five cracks forming and developing along the roof.The roof is simplified as a clamped-supported one-way slab,proved by the observation that the maximum strain of the transverse bar is much larger than that of the longitudinal bar.Dynamic responses of the roof slab are predicted by dynamic Euler beam theory,which can consistently predict the roof displacement under large-scaled-distance explosion.Compared with the UUT reinforced with steel bars,the BBRU has advantages in blast resistance with smaller deflections and more evenly-distributed cracks when the scaled distance is smaller than 1.260 m/kg1/3 and the steel bars enter plastic state.Longer elastic defamation of the BFRP bars endows the UUT more excellent blast resistance under small-scaled-distance explosions.     

Robust cubature Kalman filter method for the nonlinear alignment of SINS

Nonlinear initial alignment is a significant research topic for strapdown inertial navigation system(SINS).Cubature Kalman filter(CKF)is a popular tool for nonlinear initial alignment.Standard CKF assumes that the statics of the observation noise are pre-given before the filtering process.Therefore,any unpredicted outliers in observation noise will decrease the stability of the filter.In view of this problem,improved CKF method with robustness is proposed.Multiple fading factors are introduced to rescale the obser-vation noise covariance.Then the update stage of the filter can be autonomously tuned,and if there are outliers exist in the observations,the update should be less weighted.Under the Gaussian assumption of KF,the Mahalanobis distance of the innovation vector is supposed to be Chi-square distributed.Therefore a judging index based on Chi-square test is designed to detect the noise outliers,determining whether the fading tune are required.The proposed method is applied in the nonlinear alignment of SINS,and vehicle experiment proves the effective of the proposed method.     

A novel launch dynamics measurement system for multiple launch rocket system and comparative analysis with numerical simulations

In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket's departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.     

The effect of al particle size on thermal decomposition,mechanical strength and sensitivity of Al/ZrH2/PTFE composite

To study the thermal decomposition of Al/ZrH2/PTFE with different Al particle size as well as mechanical strength and impact sensitivity under medium and low strain rates, molding-vacuum sintering was adopted to prepare four groups of power materials and cylindrical specimens with different Al particle size. The active decomposition temperature of ZrH2 was obtained by TG-DSC, and the quasi-static me-chanics/reaction characteristics as well as the impact sensitivity of the specimen were studied respec-tively by quasi-static compression and drop-hammer test. The results show that the yield strength of the material decreased with the increase of the Al particle size, while the compressive strength, failure strain and toughness increased first and then decreased, which reached the maximum values of 116.61 MPa, 191％, and 119.9 MJ/m respectively when the Al particle size is 12—14μm because of particle size grading. The specimens with the highest strength and toughness formed circumferential open cracks and reacted partly when pressed. Those with developmental cracks formed inside did not react. It is considered that fracture of specimens first triggered initial reaction between Al and PTFE to release an amount of heat. Then ZrH2 was activated and decomposed, and participated in subsequent reaction to generate ZrC. The impact sensitivity of the specimens decreased with the increase of Al particle size.     

Interval uncertain optimization for damping fluctuation of asegmented electromagnetic buffer under intensive impact load

Aiming at the problems of demagnetization effect of electromagnetic buffer (EMB) caused by high ve-locity under intensive impact load and the difficulty and error of machining composite thin-walled long tube, a segmented EMB is proposed. The inner tube and air-gap are divided into initial segments and the traversing segments. Through theoretical analysis, impact test and simulation, it can be found that the RRF curve has two peaks. Firstly, in order to reduce the resultant resistance force (RRF) peaks, the sensitivity analysis based on optimal Latin hypercube design (OLHD) and polynomial regression was performed. The results show that the smallest contribution ratio to the dynamic response is the seventh and ninth segments of the inner tube, which are less than 1％. Then, fully considering the uncertain factors, important parameters are selected for uncertain optimization after sensitivity analysis. The in-terval order and interval probability degree methods are used to establish interval uncertain optimiza-tion model of the RRF considering robustness. The model was solved using an interval nested optimization method based on radial basis function (RBF) neural network. Finally, the Pareto front is obtained and numerical simulation is performed to verify the optimal value. It indicates that the two kinds of RRF peak is obviously reduced, and the optimization object and strategy are effective.     

The deformation and failure mechanism of cylindrical shell and square plate with pre-formed holes under blast loading

The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971. To calibrate the numerical model, the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data. The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading. The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically. The local and global deformation curves, degree of damage, change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained, compared and analyzed, it can be concluded as: (1) The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration; (2) The existence of pre-formed holes not only lead to the increasing of stress concentration around the holes, but also release the stress concentration during whole response process; (3) There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes, respectively. and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation; (4) The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance, while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.     

一类非线性反应扩散系统

用非线性分析的方法,研究一类带混合非齐次边界条件的肺动脉毛细血管中血红蛋白的氧化反应扩散系统,并引进局部上、下解的概念,借助构造局部上、下解,在任一有限时间区间内得到解的存在性,从而证明了解是整体存在的.     

两栖车辆水阻力构成研究

分析了排水型两栖车辆的水阻力构成,当两栖车辆高速航行时,形状阻力占主要成分,形状阻力是影响两栖车辆水上机动性的主要因素,模型拖曳试验结果验证了该分析结果.