Partial penetration of annular grooved projectiles impacting ductile metal targets

Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance. One special ballistic performance is the embedding effect, which can achieve a delayed high-explosive reaction on the target surface. This embedding effect includes a rebound phase that is significantly different from the traditional penetration process. To better study embedment behavior, this study proposed a novel nose shape called an annular grooved projectile and defined its interaction process with the ductile metal plate as partial penetration. Specifically, we conducted a series of low-velocity-ballistic tests in which these steel projectiles were used to strike 16-mm-thick target plates made with 2024-O aluminum alloy. We observed the dynamic evolution characteristics of this aluminum alloy near the impact craters and analyzed these characteristics by corresponding cross-sectional views and numerical simulations. The results indicated that the penetration resistance had a brief decrease that was influenced by its groove structure, but then it increased significantly-that is, the fluctuation of penetration resistance was affected by the irregular nose shape. Moreover, we visualized the distribution of the material in the groove and its inflow process through the rheology lines in microscopic tests and the highlighted mesh lines in simulations. The combination of these phenomena revealed the embed-ment mechanism of the annular grooved projectile and optimized the design of the groove shape to achieve a more firm embedment performance. The embedment was achieved primarily by the target material filled in the groove structure. Therefore, preventing the shear failure that occurred on the filling material was key to achieving this embedding effect.     

Pressure relief of underground ammunition storage under missile accidental ignition

Safety of underground ammunition storage is an important issue, especially during the accidental ignition of missiles. This work investigates the pressure and temperature distribution of the multi-layer underground ammunition storage with a pressure relief duct during the accidental ignition process of the missile. A large-scale experiment was carried out using a multi-layered restricted space with a pressure relief duct to simulate the underground ammunition store and a solid rocket motor to simulate the accidental ignition of the missile. The results show that when the motor gas mass flow increased by 5.6 times, the maximum pressure of the ammunition storage increased by 5.87 times. At a certain motor flow rate, when the pressure relief exhaust area at the end of the relief duct was reduced by 1/2, the maximum pressure on the first layer did not change. But the rate of pressure relief was reduced and the time delayed for the pressure of ammunition store to drop to zero. In this experiment, when the motor ignition position was located in to the third layer ammunition chamber, the maximum pressure was reduced by 32.9％ and also reduced the rate of change of pressure. In addition, for the experimental conditions, the theoretical analysis of the pressure relief of the ammunition storage is given by a simplified model. Based on the findings, some suggestions to the safety protection design of ammunition store are proposed.     

基于遗传算法的航空兵出动架次计算方法

针对航空兵出动架次计算问题,基于资源受限项目调度理论进行问题描述和建模,以给定兵力对目标任务的最大出动架次为效能指标,分析影响因素和约束条件,建立了问题数学模型.根据问题模型特点,采用遗传算法进行求解,针对染色体编码问题,设计了一种扩展任务列表编码方法;针对初始解集求解问题,提出了一种基于优先规则的出动架次分配算法.并构建了航空兵出动架次计算仿真算例对问题模型和求解算法进行验证,实验结果表明,所提模型和算法能够有效求解大规模航空兵出动架次计算问题.     

陆战平台分布式综合模块化系统架构建模方法

分布式综合模块化系统架构,成为航空应用领域的主流架构和发展趋势.我国空军已进行了分布式综合模块化系统架构研究设计和仿真评估,但缺乏系统级的架构优劣评估.兵器领域已将综合模块化系统架构应用于型号项目中,但在分布式综合模块化架构方面,尚未在具体项目中应用.针对分布式综合模块化系统架构缺乏系统级评估手段的问题,提出一种陆战平台分布式综合模块化系统架构建模方法.根据系统架构评估需求,建立不同层级实体的模型及约束,分别对应陆战平台信息控制系统的业务层、操作系统分区层、模块层、子系统层、系统层;在层级划分的基础上,定义各层级模型的属性;通过对评估指标中的综合度、耦合度进行评估计算,对系统架构建模方法进行验证.系统架构建模方法为系统架构评估提供了一种参考.     

卧式储油罐罐体变位模型与罐容表标定

针对储油罐罐体变位影响油品计量精度的问题,建立了球冠形封头卧式储油罐罐体变位模型,将罐体变位后的油位高度转换成无变位时的油位高度,再利用罐体无变位时的储油体积计算模型得到变位后储油体积与油位高度的关系。分析了罐体变位对罐容表的影响,提出了一种基于最小二乘原理的变位参数识别算法,最后对该变位模型进行了检验,并采用插值算法重新标定了变位后的罐容表。结果表明:该变位模型与实际情况基本相符,变位参数识别算法能估计出罐体倾斜角度和偏转角度。     

关系数据语义集成中的查询语言转换方法研究

为解决关系数据语义集成中语义查询语言和关系模型查询语言的转换问题,定义了SPARQL(Simple Protocol And Rdf Query Language)图模式的关系代数和五种基本运算的查询语义,给出了该关系代数与SQL语句之间的对应关系,在此基础上,提出了SPARQL到SQL的查询转换算法,并通过实例进行了说明。     

浅谈成人高校后勤管理改革

当前成人高校的后勤存在的问题,决定必须对其进行改革,改革应遵循解放思想、实事求是的原则;因地、因校制宜的原则;坚持"三服务,两育人"的原则;维护学校稳定原则;集中统一、整体发展等原则.改革的根本途径在于后勤的社会化,其实质就是建立现代后勤制度.     

基于继电辨识自整定控制器的研究

为了在复杂的动态操作环境下实现PID参数的自整定,探讨了基于继电反馈的参数自整定法,仿真结果表明使用该方法可以轻易实现自整定.一方面证明了这种识别和控制程序的先进、简单.另一方面,与以往的方法相比,这种新控制器有更强的抗干扰性、更好的鲁棒性能和动态响应.此外,该方法成功地应用于有大的时间滞后的一阶加纯滞后(FOPDT)系统,这是其他传统PID自整定方法所不能实现的.     

Using a birth‐and‐death process to estimate the steady‐state distribution of a periodic queue

If the number of customers in a queueing system as a function of time has a proper limiting steady‐state distribution, then that steady‐state distribution can be estimated from system data by fitting a general stationary birth‐and‐death (BD) process model to the data and solving for its steady‐state distribution using the familiar local‐balance steady‐state equation for BD processes, even if the actual process is not a BD process. We show that this indirect way to estimate the steady‐state distribution can be effective for periodic queues, because the fitted birth and death rates often have special structure allowing them to be estimated efficiently by fitting parametric functions with only a few parameters, for example, 2. We focus on the multiserver M_t/GI/s queue with a nonhomogeneous Poisson arrival process having a periodic time‐varying rate function. We establish properties of its steady‐state distribution and fitted BD rates. We also show that the fitted BD rates can be a useful diagnostic tool to see if an M_t/GI/s model is appropriate for a complex queueing system. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 664–685, 2015     

面向战略预警数据化辅助决策关键问题研究

从美国空海一体战的产生背景和意图入手,提出战略预警信息支援的重要性。结合战略学理论,提出基于战略态势感知的预警手段,总结了战略判断方法论的具体要求和运用。由于大数据情报已经成为信息化作战时代的根本战场生态,军事领域的很多问题都与大数据密切相关。为此,提出了基于情报分析的战略预警数据化辅助决策,研究面向战略预警信息支援的数据需求体系和处理流程等关键问题。