小型无人机协同覆盖侦察路径规划

针对多架小型无人机对含有障碍的区域覆盖侦察最佳路径规划问题,首先用方形单元格将待侦察区域离散化,利用基于初始位置的划分方法划分出与无人机对应的子区域,把问题转化为单无人机优化问题以降低计算复杂度;然后在最小生成树的基础上提出节点交换法,对各子区域的形状和最小生成树进行调整优化;最后依据优化后的最小生成树为每个子区域构建侦察路径。仿真验证了该方法产生的规划路径能够完全覆盖指定区域且无重叠,路径长度和转弯数最小。     

中子活化分析中煤样厚度及探测器位置的选择

利用MCNP5程序包模拟14MeV脉冲中子照射一定厚度煤样,并通过时间控制获得非弹γ能谱和俘获γ能谱,再利用计数率的高低确定γ能谱的获取位置.结果表明:当煤样厚度为20cm时,非弹γ能谱的计数率达到饱和;当煤样厚度为35cm时,俘获γ能谱的计数率达到饱和.     

基于FDR控制的基金绩效评价

基于2002-2013年我国主动管理型开放式基金的日收益率数据,采用FDR(false discovery rate)方法从风格择时、投资目标、基金特征、绩效持续性四个层面系统分析了运气因素对基金绩效的影响,主要结论包括:运气对基金绩效的影响是不对称的,业绩好的基金受运气的影响要大于业绩差的基金;在剔除运气因素后,少数业绩好的基金具备真正的择股能力,大多数基金在扣除管理与交易等费用后都无法取得超额收益;风格择时对基金的真实绩效有较大影响,意味着投资者依据过去绩效选择基金时要兼顾基金的择时表现;根据投资目标以及基金特征对真实绩效的差异化影响,投资者能更有效地选择出真正有能力的明星基金;通过FDR控制的基金绩效是不可持续的.     

Underdetermined DOA estimation and blind separation of non-disjoint sources in time-frequency domain based on sparse representation method

This paper deals with the blind separation of nonstation-ary sources and direction-of-arrival （DOA） estimation in the under-determined case, when there are more sources than sensors. We assume the sources to be time-frequency （TF） disjoint to a certain extent. In particular, the number of sources presented at any TF neighborhood is strictly less than that of sensors. We can identify the real number of active sources and achieve separation in any TF neighborhood by the sparse representation method. Compared with the subspace-based algorithm under the same sparseness assumption, which suffers from the extra noise effect since it can-not estimate the true number of active sources, the proposed algorithm can estimate the number of active sources and their cor-responding TF values in any TF neighborhood simultaneously. An-other contribution of this paper is a new estimation procedure for the DOA of sources in the underdetermined case, which combines the TF sparseness of sources and the clustering technique. Sim-ulation results demonstrate the validity and high performance of the proposed algorithm in both blind source separation （BSS） and DOA estimation.     

Benthic foraminiferal δ~(13)C minimum events in the southeastern Okhotsk Sea over the last 180 ka

A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.     

The effects of the non-breaking surface wave-induced vertical mixing on the forecast of tropical cyclone tracks

The Weather Research and Forecasting model(WRF)is configured for the region of(15°–41°N,105°–135°E),which covers the same area with the MASNUM(Key Lab.Marine ScienceNumerical Modeling,State Oceanic Administration)wave-tide-circulation coupled operational forecast system.Three numerical experiments are implemented to investigate the effects of the real-time forecasted sea surface temperature(SST)and the nonbreaking wave-induced vertical mixing(Bv)on the track forecast of all 33 tropical cyclones(TC)in the model domain area during 2008 and 2011.The first experiment employs NCEP FNL(NCEP final analysis)SST as WRF’s bottom condition as the Control run,which is also the default setup of WRF.The second and third experiments use real-time forecasted SST from the MASNUM forecast system with and without Bv,respectively.The forecasted track results are compared with Japan Meteorological Agency’s best track data.For 24-h forecast,the averaged TC position error of Experiment with Bv is reduced by 9%compared to the Control experiment,while the forecasted track error of Experiment without Bv is reduced by only2%compared to the Control experiment.For the 48-h forecast,the averaged track errors are reduced by 10%and6%with Bv and without Bv compared to the Control experiment,respectively.These results suggest that the real-time forecasted SST can improve the performance of WRF in forecasting TC track,and the Bv plays an important role in reducing the forecast error of TC track.Comparatively,Bv can improve more on the track of stronger TC.     

New rapid transfer alignment method for SINS of airborne weapon systems

Transfer alignment is an effective alignment method for the strapdown inertial navigation system （SINS） of airborne weapon systems. The traditional transfer alignment methods for large misalignment angles alignment use nonlinear transfer align- ment models and incorporate nonlinear filtering. A rapid transfer alignment method with linear models and linear filtering for ar- bitrary misalignment angles is presented. Through the attitude quaternion decomposition, the purpose of transfer alignment is converted to estimate a constant quaternion. Employing special manipulations on measurement equation, velocity and attitude linear measurement equations are derived. Then the linear trans- fer alignment model for arbitrary misalignment angles is built. An adaptive Kalman filter is developed to handle modeling errors of the measurement noise statistics. Simulation results show feasibili- ty and effectiveness of the proposed method, which provides an alternative rapid transfer alignment method for airborne weapons.     

聚偏氟乙烯（PVDF）/聚己内酯（PCL）共混体系的晶体结构和形貌

使用偏光显微镜（POM）和扫描电子显微镜（SEM）等测试手段,研究了PVDF/PCL共混体系在不同配比和结晶温度下晶型结构、球晶和片晶形貌的变化规律。结果表明：PVDF在低温下形成α型球晶,在高温下形成γ型球晶;两种不同晶型的球晶尺寸均随着结晶温度的升高而增大;α型PVDF环带球晶的环带间距随着体系内PCL含量的增多而增大。此外,共混体系内γ型PVDF球晶的含量也随着PCL含量的增大而增大。     

闽浙皖赣根据地的妇女工作探究

闽浙皖赣根据地是1928年方志敏领导创建的著名的苏维埃根据地。根据地妇女翻身获得解放,摆脱封建礼教的束缚,开始参加社会工作,她们积极投入经济生产取得经济上的独立,参加政治活动拥有了选举权和被选举权,英勇地参加军事斗争,为革命事业做出伟大的贡献。根据地广大妇女的工作具有积极性、政治性、平等性、军事性等特点。根据地妇女工作遇到了较多的历史和社会的阻碍,主要是男人对妇女的歧视和男尊女卑思想严重,妇女家庭社会工作强度大、大部分工作技术含量低,苏区妇女工作总体目标不够明确等。     

初道屏蔽效应对低能电子碰撞H(e,2e)反应的影响

考虑初道屏蔽效应,研究了低能电子碰撞H(e,2e)的反应过程.计算了共面非对称几何条件下能量为27.2 eV的入射电子碰撞H(e,2e)反应的三重微分截面(TDCS),将其计算结果与3C、DS3C和CDS3C模型所得结果及实验数据进行了比较,结果表明CDS3C模型能对上述碰撞过程成功描述,改善了与实验结果的符合程度.