一种新型高精度低功耗守时芯片

以测时测距体制为基础的定位系统中,提高时间精确度是改善导航接收机性能的一个关键因素。然而,在便携或手持式导航设备中,现有的守时芯片难以在低功耗的条件下实现高计时精度。针对上述矛盾,本文提出了一种全新的守时芯片电路结构,通过直接温度补偿计时,以及低功耗连续工作和高功耗间歇突发工作相结合,实现了优于0.5ppm级别的守时精度和低于200μW待机功耗,可替换传统音叉型RTC芯片,提高便携或手持式导航设备性能。     

基于蚁群算法的Costas跳频信号自测速方法

分析了速度对Costas跳频信号回波的影响,用波形熵作为性能指标函数,研究了基于蚁群算法的Costas跳频信号自测速方法,仿真验证表明,这种测速方法能够明显提高测速的精度.     

多平台协同防空武器调度方案评价指标

针对多平台协同防空武器调度问题的特点,通过构建防空武器的战斗动作模型,实现了对武器调度方案的形式化表述.在此基础上,从防御作战能力优势性和作战资源耗费合理性两个方面,对决定武器调度方案优劣的主要因素进行系统分析,提出了四个具体的量化指标,并建立了相应的计算模型.最后,通过一个算例对所提出评价指标的实用性及其有效性进行了验证.结果表明:该套评价指标为多平台协同防空武器调度方案的评定和择优提供了一套系统、客观的标准.     

Bayesian sampling plans for exponential distributions with interval censored samples

This article studies the problem of designing Bayesian sampling plans (BSP) with interval censored samples. First, an algorithm for deriving the conventional BSP is proposed. The BSP is shown to possess some monotonicity. Based on the BSP and using the property of monotonicity, a new sampling plan modified by the curtailment procedure is proposed. The resulting curtailed Bayesian sampling plan (CBSP) can reduce the duration time of life test experiment, and it is optimal in the sense that its associated Bayes risk is smaller than the Bayes risk of the BSP if the cost of the duration time of life test experiment is considered. A numerical example to compute the Bayes risks of BSP and CBSP and related quantities is given. Also, a Monte Carlo simulation study is performed to illustrate the performance of the CBSP compared with the BSP. The simulation results demonstrate that our proposed CBSP has better performance because it has smaller risk. The CBSP is recommended. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 604–616, 2015     

地基伪卫星导航系统的伪距精度估计方法

地基伪卫星导航系统的伪距和伪距变率精度对评估系统的导航性能或其信息与其他系统导航信息的融合意义重大。目前的伪距和伪距变率精度估计方法基本上都是针对卫星导航系统的,并且没有充分考虑地基伪卫星导航系统自身的特点。通过构造伪距和伪距变率精度观测量,利用地基伪卫星导航系统可产生较差定位构型的特点,提出了一种在外测系统定位定速精度较差且存在杆臂长度的情况下仍然能够获取准确估计量的伪距和伪距精度估计方法。仿真结果表明所提方法可有效地估计出伪距和伪距变率的精度而且具有较强的适用性。     

改进型Voronoi图和动态权值A*算法的无人机航迹规划

针对实际作战环境中的不同威胁等级和不同威胁实体的威胁源,提出了改进型的Voronoi图,并建立了基于改进型Voronoi图的航迹规划空间;基于A*算法的估价函数在不同阶段对指标的敏感度不同,在传统的启发式A*搜索算法基础上提出了动态权值A*搜索算法,提高了航迹搜索的效率,实现了航迹搜索过程快速性和准确性的结合。最后通过Matlab仿真计算出由动态权值A*算法得到的最优航迹,并进行了航迹的平滑处理,仿真表明了该方法的可行性。     

基于Petri网的水面舰艇区域防空作战使用流程优化方法

针对水面舰艇区域防空的反导作战过程,以缩短水面舰艇区域防空的协同反导时间,提高水面舰艇区域防空作战效能,优化区域防空作战使用流程为目标,引入Petri网技术对水面舰艇对空防御作战使用流程的时间性能进行模型分析。该模型运用模糊数学和动态规划相结合的优化技术,找出对空防御作战使用流程的关键路径;针对三种对空防御模式设计流程,考虑来袭目标的时间紧迫度,以优先火力抗击和我方最小资源为目标函数,对三种对空防御模式的作战使用效率进行对比仿真验证。仿真结果表明:运用基于petri网的流程优化技术能有效简化区域防空作战使用流程,提高指挥效率。     

Does Health Spending Crowd out Defense in the United States? Evidence from Wavelet Multiresolution Analysis

Abstract

This study investigates the association between defense and health spending using multi-resolution analysis incorporating the structural change model. Our empirical results suggested that a negative correlation between defense and health spending persists over the entire period of 1941–2013 in the very long-run (over 16 years cycle), but there is a change in correlation between defense and health spending in the short-run (2–4 years cycle), medium-run (4–8 years cycle), and long-run (8–16 years cycle) during the same period. In particular, there appears to have been a trade-off relationship between defense and health spending during the ex-Korean War period, but there was a complementary relationship between defense and health spending during the post-Korean War period. The crowding-out effect of health spending on defense spending during the period when the Affordable Care Act was put into effect relies on the strength of the positive correlation in the long-run (8–16 years cycle) and negative correlation in the short-run (2–4 years cycle) and very long-run (over 16 years cycle).     

基于CIVA的曲轴R角缺陷相控阵超声检测方法

针对发动机曲轴R角部位的缺陷检测,提出使用相控阵超声的方法.首先,对曲轴R角损伤机理进行分析,确定缺陷定量检测的参数依据;其次,通过商业超声仿真检测软件CIVA,对曲轴R角损伤部位的检测方法进行探索;最后,采用相控阵超声仪器对预置的5 mm深人工裂纹进行检测,实现裂纹深度最佳检测方案的判定.研究表明:在考虑实际检测可行性的前提下,通过建立仿真与实际检测之间的联系,超声仿真检测软件CIVA可以很好地指导实际检测工作,且采用线阵探头进行扇形扫查可实现曲轴R角缺陷的有效检测.     

碳纤维混凝土单轴受压应力-应变本构关系

碳纤维混凝土受压应力-应变全曲线研究是对其基本力学性能进行全面认识的基础,也是表现碳纤维混凝土基本受压特性的综合宏观反映。对9组（碳纤维体积分数分别为0,0.2%,0.4%,0.6%,0.8%,1.0%,1.2%,1.4%,1.6%）碳纤维混凝土试件进行了立方体和棱柱体抗压强度试验,结果表明碳纤维混凝土立方体和棱柱体抗压强度随碳纤维体积分数的增加呈下降趋势,峰值应变随碳纤维体积分数的增加呈增大趋势。基于各体积分数碳纤维混凝土的棱柱体抗压强度和峰值应变的试验数据,拟合得到了棱柱体抗压强度和峰值应变与体积分数之间的函数表达式。利用微机控制电液伺服压力试验机测定了9组碳纤维混凝土应力-应变全曲线,参照非线弹性理论的混凝土单轴受压应力-应变本构模型,根据测得的全曲线应力-应变数据,拟合得到了应力-应变全曲线上升段表达式参数和下降段表达式参数,最后给出了基于碳纤维体积分数变化的碳纤维混凝土单轴受压应力-应变本构方程。