基于中红外痕量甲烷检测的地震预警仪

随着地震断裂带气体观测技术的快速发展,为了对地震进行精确的预报,减少因地震给人民群众生命和财产带来的损失,根据甲烷气体的释放与地震前上地壳岩石的微裂隙有直接关系的这一微观变化,设计并研制中红外痕量甲烷气体检测仪。仪器采用激发波长为7.65 μm的量子级联激光器(QCL),结合双光路长度为76 m的多次反射herriott长光程气体吸收池,可以在4 s的采样时间内实现40 nmol·mol-1气体检测灵敏度。同时,采用半导体激光器频率调制直接光谱吸收技术,降低了该仪器噪声的主要来源1/f噪声,使气体检测下限达到5 nmol·mol-1 (40 s采用时间)。在野外实验中,利用可控震源车作为模拟地震源,将6个痕量甲烷检测仪以100 m为距离等间隔放置,对距震源中心不同距离下的地表面甲烷气体浓度进行动态测量。实验表明,该仪器可以监测地震前地下痕量甲烷气体的释放,为地震前兆预警提供新的途径。     

Tb3+,Yb3+共掺杂LuBO3荧光粉的下转换发光

利用水热法成功合成了近红外量子剪裁荧光粉LuBO3∶15;Tb3+,x; Yb3+(x=0,1,2,4,8,12).通过X射线衍射(XRD)、光致发光谱(PL)、激发谱(PLE)和荧光寿命测试了合成物质的物相结构与发光性质.在286 nm(Tb3+∶7 F6→5D)紫外光激发下,观察到了Tb3∶5D4→7Fj(J=6,5,4,3)可见波段特征发射光和Yb3+:2F5/2→2F7/2的近红外光.研究了Yb3+浓度与激发发射光谱和荧光寿命之间的关系,表明Tb3+和Yb3+之间存在能量传递.当Tb3和Yb3+掺杂摩尔浓度分别为15;和2;时,近红外发射最强.计算得知,其最大下转换量子效率为160.74;.     

Quasi-Periodic Solutions and Asymptotic Properties for the Isospectral BKP Equation

In this paper, based on a Riemann theta function and Hirota's bilinear form, a straightforward way is presented to explicitly construct Riemann theta functions periodic waves solutions of the isospectral BKP equation. Once the bilinear form of an equation obtained, its periodic wave solutions can be directly obtained by means of an unified theta function formula and the way of obtaining the bilinear form is given in this paper. Based on this, the Riemann theta function periodic wave solutions and soliton solutions are presented. The relations between the periodic wave solutions and soliton solutions are strictly established and asymptotic behaviors of the Riemann theta function periodic waves are analyzed by a limiting procedure. The N-soliton solutions of isospectral BKP equation are presented with its detailed proof.     

基于LIBS技术的钢铁合金中元素多变量定量分析方法研究

针对钢铁合金样品元素组成相对复杂,基体效应较严重的问题,利用激光诱导击穿(LIBS)光谱技术对钢铁合金中的元素进行了定量分析。以Nd∶YAG脉冲激光器基频1 064 nm波长激光作为激发光源,采用中阶梯光栅光谱仪和ICCD分光探测钢铁合金样品的LIBS光谱。通过优化实验确定最佳探测延时为1.5 μs,最佳探测门宽为2 μs,激光聚焦点位置在实验样品靶面以下1.5 mm。采用单变量定量分析、多变量线性回归和偏最小二乘(PLS)三种方法分析钢铁合金中Cr元素和Ni元素的含量。结果表明,采用单变量定标方法定标曲线相关系数不高,对待测样的预测误差相对较大,难以有效地定量分析基体元素复杂的钢铁合金中金属元素的含量;采用多变量线性回归分析方法能有效提高定量分析的精度;采用PLS方法得到的Cr和Ni元素的拟合曲线相关系数r分别为0.981和0.995,对两个待测样品中Cr元素和Ni元素的预测相对误差在6.4%和7.1%以内,分析结果优于多变量线性回归方法。可见,采用多变量校正的PLS方法能更有效地校正基体效应对定量分析的影响,提高定量分析的精度。     

Activation cross-section measurement of a sort of nuclide produced with a target including two isotopes

Based on a formula used to calculate the activation cross-section sum of two reactions producing a sort of nuclide with a target including two isotopes, the related problems in some references have been analyzed and discussed. It is pointed out that the calculation methods of the cross-section sum of two reactions producing the same radioactive nuclide for two isotopes in some references are improper and usually it is impossible to obtain the correct cross-section sum of two reactions producing the same radioactive nuclide for two isotopes in the case of using natural samples. At the same time, the related concepts are clarified and the correct processing method and representation are given. The comparison with the experimental results show that the theoretical analysis results are right.     

空间调制傅里叶变换红外光谱仪干涉系统透射效率研究

光学系统表面的反射与材料的吸收会降低空间调制傅里叶变换红外光谱仪中光的透过率。通过对干涉系统透过率函数的计算和对采样干涉图与复原光谱的仿真,结果显示透过率函数作用下的干涉图像对比度下降,复原光谱中的谱线强度发生衰减。分析表明,干涉图像对比度的下降主要是由分束器对入射光的有效反射引起的,而谱线强度的衰减则是由与增透膜的光强反射率R₁、分束膜的光强反射率R₂和材料的吸收系数α有关的透射效率函数所决定。通过分析论证,对于本文所研究的光谱波段,可以不考虑材料的吸收,所以透射效率主要由R₁和R₂决定。由此,将透射效率作为设计指标,根据系统的设计需求,就可以得到增透膜与分束膜光强反射率的容限值。     

子孔径拼接中系统误差的修正方法

为了提高大口径光学元件子孔径拼接测量的检测精度,提出一种平面绝对测量技术,修正子孔径拼接过程中产生的系统误差。利用改进的三面互检法获得参考平面的面形数据,采用这些测量数据构建基于Zernike多项式的参考面面形误差修正波面,在拼接过程中运用误差修正波面对获得的子孔径测量数据进行实时修正,并与全口径直接测量结果进行对比,结果PV（peak value,PV,峰谷值）误差从0.072 1 减少到0.028 6 。结果表明该方法有效减少了参考平面系统误差对拼接测量精度的影响,提高了大口径光学元件的检测精度。     

NUMERICAL ANALYSIS OF THE STRESS CONCENTRATION IN REVERSE K-JOINTS

逆K 型管节点广泛应用于海洋平台,其强度是平台结构安全评估的重要课题. 基于ANSYS 软件,应用分区域网格划分法,建立含焊缝的逆K 型管节点有限元模型,分别计算了在轴向载荷、平面内弯矩和平面外弯矩作用下焊缝周围热点应力的分布情况. 通过对105 组逆K 型管节点模型进行分析,获得了其在3 种基本载荷作用下沿焊缝的应力集中系数（stress concentration fctor,SCF）,并对主管和支管的SCF 分别进行研究,得出了几何参数对主管和支管的SCF 及极值位置的影响规律.     

Effects of Bond Alternation on the Ground-State Phase Diagram of One-Dimensional XXZ Model

The ground-state properties and quantum phase transitions (QPTs) of the one-dimensional bond-alternative XXZ model are investigated by the infinite time-evolving block decimation (iTEBD) method. The bond-alternative effects on its ground-state phase diagram are discussed in detail. Once the bond alternation is taken into account, the antiferromagnetic phase (Δ > 1) will be destroyed at a given critical point and change into a disordered phase without nonlocal string order. The QPT is shown to be second-order, and the whole phase diagram is provided. For the ferromagnetic phase region (Δ < -1), the critical point r^c always equals 1 (independent of Δ), and the QPT for this case is shown to be first-order. The dimerized Heisenberg model is also discussed, and two disordered phases can be distinguished by with or without nonlocal string orders. Both the bipartite entanglement and the fidelity per site, as two kinds of model-independent measures, are capable of describing all the QPTs in such a quantum model.     

应用理性优化蚁群算法提高激光三维复制的重现度

三维复制人工耳和打印手枪把激光三维复制技术推向新的一页。激光三维扫描是激光应用中一个新兴的重要领域,在三维复制中扮演着无可替代的角色,其复制精度在目前所有复制技术中是最高的。而重现度标志着复制结果与复制对象几何形状上的一致程度,是激光三维复制最重要的指标。分析了激光三维复制的误差,得出激光扫描的点云数据处理是减小误差、提高重现度的关键所在的结论。主要创新点在于,在传统蚁群算法的基础上,将提出理性优化蚁群算法应用于激光三维复制中的数据处理。经计算对比发现,有效减小了复制的误差,提高了复制的重现度。