车用再制造发动机验收检验台架磨合规范试验研究

对未经磨合的再制造发动机新品进行动力性能试验,试验结果与原机标准相差较大,经分析后认为未进行充分磨合是性能不达标的主要原因。针对再制造发动机的出厂验收技术特点,制定了小负荷循环磨合规范,并对起初推断进行了试验验证。根据磨合过程中发动机动力性能的变化规律,通过试验对磨合规范进行了优化,总结出了快速有效的台架磨合规范。试验结果表明：快速磨合规范不仅能够提高磨合效率,而且保证了磨合效果。     

基于GeoHash索引的A算法优化

A*(A Star)算法进行最短路径计算时,一般采用曼哈顿函数作为最优邻接点的评估标准,在算法执行的过程中,需要对每一步每个邻接点进行计算,判断出当前最优邻接点,然后迭代执行下一步,在数据量较大的情况下,算法的时间复杂度呈几何增长.使用GeoHash索引算法代替曼哈顿函数作为评估标准,在有地理坐标信息的网络拓扑中进行最短路径查找,直接以GeoHash编码索引值作为判断标准,进行快速查找.GeoHash值是经纬度经过一系列编码转换后的实际值,能够拓扑网格中的属性值,减少算法的计算时间,优化算法的时间复杂度.提高A*算法在道路规划、运行调度、无人驾驶路径分析时的最短路径计算时间,可增加实际应用广泛性.     

战场多级核生化态势生成方法研究

详细介绍和描述了核生化态势的分类问题,提出了战场多级核生化态势的概念,分别对作业级、作战指挥级、作战筹划级核生化态势的要素及生成方式进行了研究,并进行了对比分析.多级核生化态势可以为不同层级的用户提供专业、有效的态势信息,满足核生化作战的技术需求.     

基于双谱切片小波包的雷达体制识别技术

根据机械扫描雷达、一维相控阵雷达和二维相控阵雷达扫描方式的差异,通过对3种体制雷达进行双谱分析、切片化处理以及小波包分解,提出了双谱切片小波包的概念,并根据此特征用支持向量机对不同体制的雷达进行识别.仿真结果表明:该方法在噪声占比为0～20％时,可分性好,并且在噪声占比增大时,通过该特征仍能对不同体制的雷达进行有效识别.     

Effects of total pressures and equivalence ratios on kerosene/air rotating detonation engines using a paralleling CE/SE method

In this paper, the kerosene/air rotating detonation engines(RDE) are numerically investigated, and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation, instabilities, and propulsive performance. A hybrid MPI + OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC) systems. A series of cases with the total pressure of 1 MPa, 1.5 MPa, 2 MPa, and the equivalence ratio of 0.9, 1, 1.4 are simulated. On one hand, the total pressure shows a significant impact on the instabilities of rotating detonation waves. The instability phenomenon is observed in cases with low total pressure (1 MPa) and weakened with the increase of the total pressure. The total pressure has a small impact on the detonation wave velocity and the specific impulse. On the other hand, the equivalence ratio shows a negligible influence on the instabilities, while it affects the ignition process and accounts for the detonation velocity deficit. It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition. Little difference was observed in the thrust with different equivalence ratios of 0.9, 1, and 1.4. The highest specific impulse was obtained in the lean fuel cases, which is around 2700 s. The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.     

Influences of different crossing types on dynamic response of underground cavern subjected to ground shock

An intersecting cavern is a common structural form used in underground engineering, and its safety and stability performance directly control the service performance of the whole project. The dynamic re-sponses of the three kinds of crossing type (+-shaped, T-shaped, L-shaped) caverns subjected to ground shock were studied by numerical simulation. The velocity plus force mode boundary setting method was proposed in the coupled static and dynamic analysis of a deep underground cavern. The results show that, among the three types of crossing caverns, the+-shaped cavern is the most significantly affected by the dynamic action, followed by T-shaped, and then L-shaped caverns. The vault settlement, straight wall deformation, vault peak particle velocity, effective plastic strain of surrounding rock, and maximum principal stress and strain at the bottom of the lining of the straight wall increase with the increase of cavern span. The vault settlement, straight wall deformation, effective plastic strain of surrounding rock, and the maximum principal stress and strain at the bottom of lining to the straight wall decrease with the increase of lateral pressure coefficient, and the peak particle velocity at the vault increases. The variation is small compared with the change of cavern span. The influence range of the underground cavern intersection is two cavern diameters from the intersection centre. The bottom of the straight wall at the intersection is the weak part. It is suggested to thicken the support locally to improve the stability of the cavern.     

Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging

In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process, a one month thermal aging test was carried out at 70 C with pre-strain of 0％, 3％, 6％ and 9％, respectively. The low-field 1H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages. The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging. The results showed that with the increase of aging time, the decay rate of transverse relaxation curve became faster, the transverse relaxation time decreased, the value of combined parameter qMrl increased, the proportion of crosslinking chain decreased, while the proportion of dangling chain increased. Moreover, the stress relaxation modulus increased, the crosslinking network structure of HTPB coating became denser and the degree of cross-linking increased. At the initial aging stage, the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent. With the increase of aging time, the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase. The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950, which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.     

武器装备测试系统建设与发展

武器系统在装备部队使用之前,都要经过长时间反复、严格的性能检测和试验,以确保武器系统的先进性和精确性。简要介绍了武器装备测试系统建设概况,阐述了新型武器系统的特点以及对测试系统的要求,重点说明了武器装备测试系统的未来发展重点以及相关的测试系统理论与技术。     

基于FCM与粗糙集的连续数据知识挖掘方法

对连续数据知识挖掘可采用模糊C均值聚类将其离散化,再应用粗糙集进行约简.文中针对该过程中样本数据离散化后出现多个聚类中心隶属度值较接近的情况,提出了隶属度重叠度的方法来扩展对应离散类别的选取.离散类别确定后再应用粗糙集理论对其进行知识挖掘,可得到连续数据的本质特性.此方法应用于汽轮机轴系振动数据的知识挖掘.与采用最大隶属度确定对应类别的方法相比,该方法不影响对连续数据的知识挖掘,并能真实反映连续数据的特性.     

有色噪声下FIR模型相关辨识精度分析

本文针对离散控制系统的有限脉冲响应（ＦＩＲ）函数模型,研究了在伪随机ｍ序列输入的激励和有色噪声干扰下辨识的精度问题,纠正了参考文献中的错误,得到了有色噪声干扰下ＦＩＲ参数估计精度的显式表达式。同时,给出了辨识精度的下界和上界,分析并得到了达到上下界的条件。文中有实例分析。