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.     

柔性加工单元故障诊断的模糊Petri网模型

针对故障诊断专家系统中专家知识的模糊性和不确定性,给出用模糊Ｐｅｔｒｉ网（ＦＰＮ）模型表示模糊产生式规则（ＦＰＲ）知识的方法、知识的存储、模糊推理机制及算法的实现。同时,以ＪＣＳ—０２０（ＦＡＮＵＣ）加工中心主轴伺服故障诊断为例,说明该方法在故障诊断专家系统（ＦＤＥＳ）中应用的可行性与有效性。     

红外目标分割方法研究

红外目标分割算法对红外目标检测、跟踪具有非常重要的价值。本文利用背景和目标灰度特征,提出一种实现红外目标有效分割的方法,克服红外目标内部温度不稳定造成的误分割问题。本文方法首先采用基于灰度-显著度最大相关准则的二维直方图分割算法进行图像分割;然后,在分割后二值图上进行基于随机种子点选取的区域增长,提取背景;最后,采用形态学方法优化分割结果。相对传统的红外目标检测算法,这种算法具有更好的抗干扰能力,更强的鲁棒性。不仅可以应用于红外图像的目标分割,而且可以应用于其他类似的目标分割问题。     

Two novel critical shock models based on Markov renewal processes

In this paper, we investigate systems subject to random shocks that are classified into critical and noncritical categories, and develop two novel critical shock models. Classical extreme shock models and run shock models are special cases of our developed models. The system fails when the total number of critical shocks reaches a predetermined threshold, or when the system stays in an environment that induces critical shocks for a preset threshold time, corresponding to failure mechanisms of the developed two critical shock models respectively. Markov renewal processes are employed to capture the magnitude and interarrival time dependency of environment-induced shocks. Explicit formulas for systems under the two critical shock models are derived, including the reliability function, the mean time to failure and so on. Furthermore, the two critical shock models are extended to the random threshold case and the integrated case where formulas of the reliability indexes of the systems are provided. Finally, a case study of a lithium-ion battery system is conducted to illustrate the proposed models and the obtained results.     

论八路军第115师在全国抗战中的历史地位与作用

八路军第115师作为八路军的3个主力师之一,第一个开赴华北抗日前线,"首战平型关,威名天下扬";除一部兵力先期留守陕甘宁边区,执行保卫中共中央和中央军委的任务外,主力相继移师晋西南、挺进齐鲁大地,同时另以一部兵力像种子一样,撒在晋察冀边区、晋冀鲁豫边区和苏北等地区,开花、结果.第115师在全国抗战中的伟大历史地位与作用,是有目共睹的.     

INS 故障模型和推理方法的研究与设计

讨论了某型惯导 ( INS)设备的结构、工作流程和故障特点 ,分析了基于知识的专家系统 ( ES)常用的诊断模型和推理方法 ,在此基础上 ,设计了具体的基于对象的惯导综合层次模型及其推理机 .该模型和推理机已实际应用于该型 INS的故障诊断专家系统的设计     

武器装备全寿命费用分析及管理措施研究

分析了现代武器装备全寿命费用 (L CC)分析研究现状 ,美军对现代武器装备进行 L CC管理过程 ,并与我国的武器装备管理作了对比 ,阐述了现代武器装备效能 -费用分析方法和 L CC分析方法 ,最后提出现代武器装备 L CC管理的三点措施     

基于位置预测的靶场图像实时判读方法

在靶场经纬仪对目标实时跟踪测量时,会发生相机随机抖动的情况,引起目标在图像中大幅度运动。应对大幅度运动时,基于搜索窗口的跟踪方法容易丢失目标,而基于全图搜索的跟踪方法时效性差。针对以上问题,提出一种结合核相关滤波算法(Kernelized Correlation Filter, KCF)和目标位置预测的改进的跟踪学习检测算法(Tracking-Learning-Detection, TLD)跟踪框架。利用正交多项式最优线性滤波器及相机角度信息预测目标下一帧位置,在此区域利用KCF进行快速跟踪,可以提高跟踪的成功率和时效性,跟踪失败时再进行检测。仿真实验表明,最优线性滤波器能较准确预测目标位置,给KCF提供较准确的搜索位置,算法每帧耗时仅为1.1 ms,且定位精度优于TLD和KCF,能有效应对相机抖动的问题。靶场实际试验证明该方法可提高靶场自动判读水平,减少人工干预。     

How to deal with consumers who group to request a discount?

We investigate operations impacts of consumer‐initiated group buying (CGB), whereby consumers voluntarily form buying groups to negotiate bulk deals with retailers. This differs from regular purchasing whereby consumers visit retailers individually and pay posted prices. Upon the visit by group consumers, a retailer decides to forgo or satisfy their demand in its entirety. Turned down by a retailer, group consumers continue to visit other retailers. In the case where their group effort fails to conclude a deal, some group consumers switch to individual purchasing provided they receive a non‐negative utility by doing so. Even after a successful group event, the group consumers who forgo the event out of utility concern may switch to individual purchasing as well. Retailer competition, group size, and the chance that group consumers switch to individual purchasing upon unsatisfaction are crucial to how retailers adjust operations to deal with CGB. With retailer competition, the rise of CGB results in every consumer paying the same reduced price when group size is small but makes group consumers pay more than by purchasing individually when group size is large. This has mixed consequences on the profits for retailers in both absolute and relative terms.