基于超声波多普勒法的流通截面分区流速测量的研究

传统的超声波多普勒流量计测量的结果是大面积区域内具有统计意义的平均流速，不能反映流速在流通截面上的分布，当雷诺数变化很大时，测量误差很大。基于超声波多普勒效应，本文首次提出了通过对测量信息窗区域的控制，来实现在管流内部进行流速分区测量，进而测量出流速在流通截面上的分布。研制出发射传感器和接收传感器，分别能够产生细长的发射声束和接收声束，使得信息窗区域面积得以控制在很小的范围内，约 ２．１× ４．８ ｍｍ２，位置也被控制在设计值处，满足分区测量要求；在自行设计的模拟管道流动装置中，成功地进行了控制信息窗区域面积和位置的实验，测量值与设计值吻合很好。实现了管道流通截面上的流速分区测量。     

家蝇中乙酰胆碱酯酶的提取纯化及应用研究

研究了用Procainamide亲和层析色谱纯化家蝇头部乙酰胆碱酯酶(AChE),AChE的纯化倍数为63.27倍,产率为93.86%。通过测定AChE活力被抑制的程度可以快速测定敌敌畏和克百威残留量。研究结果表明,在0.09~200μg/L范围内,AChE抑制率与敌敌畏和克百威质量浓度的回归方程分别为Y=9.1321 Lnρ 33.904(r=0.9893),Y=10.738 Lnρ 26.125(r=0.9962);敌敌畏与克百威的检出限分别为1.13±0.42μg/L和2.28±0.76μg/L,对果蔬等实际样品的加标回收率为74%~118%。     

Gravitational Wave in Lorentz Violating Gravity

By making use of the weak gravitational field approximation, we obtain a linearized solution of the gravitational vacuum field equation in an anisotropic spacetime. The plane-wave solution and dispersion relation of gravitationaJ wave is presented explicitly. There is possibility that the speed of gravitational wave is larger than the speed of light and the easuality still holds. We show that the energy-momentum of gravitational wave in the ansiotropic spacetime is still well defined and conserved.     

Finslerian Perturbation for the ΛCDM Model

We present Finslerian perturbation for the ΛCDM model, which breaks the isotropic symmetry of the universe. The analysis on the Killing vectors shows that the Randers–Finsler spacetime breaks the isotropic symmetry even if the scalar perturbations of the FRW metric vanish. In Randers–Finsler spacetime, the modified geodesic equation deduces a modified Boltzmann equation. We propose a perturbational version of the gravitational field equation in Randers–Finsler spacetime, where we have omitted the curvature tensor that does not belong to the base space of the tangent bundle. The gravitational field equations for the gravitational wave are also presented. The primordial power spectrum of the gravitational wave is investigated. We show that the primordial power spectrum for super-horizon perturbations is unchanged. For sub-horizon perturbations, however, the power spectrum is modified.     

Riccati-type Bcklund transformations of nonisospectral and generalized variable-coefficient KdV equations

We extend the method of constructing Bcklund transformations for integrable equations through Riccati equations to the nonisospectral and the variable-coefficient equations. By taking nonisospectral and generalized variable-coefficient Korteweg–de Vries(KdV) equations as examples, their B¨acklund transformations are obtained under a more generalized constrain condition. In addition, the Lax pairs and infinite numbers of conservation laws of these equations are given. Especially, some classical equations such as the cylindrical KdV equation are just the special cases of the constrain condition.     

草酸对非对称膜成膜过程中热力学、流变学和凝胶动力学的影响

以酚酞基聚芳醚砜/草酸/N,N-二甲基乙酰胺为铸膜液体系, 考察了草酸对非对称膜成膜过程中的热力学、流变学和凝胶动力学的影响. 结果表明, 草酸的加入, 在热力学上加速了铸膜液的相分离. 成膜过程中凝胶动力学的研究结果表明, 凝胶前锋位移的平方与时间不是简单的线性关系. 将凝胶过程与非对称膜的结构相对应, 分为4个连续的凝胶过程, 凝胶速度曲线由4段具有不同速度常数的线段组成. 在凝胶过程中, 凝胶速度常数最大的是皮层.     

UPLC法测定浓缩苹果汁中阿维菌素残留量

建立了超高效液相色谱法(UPLC)测定浓缩苹果汁阿维菌素残留的方法。样品经C18固相萃取柱(250×4.6μmi.d.,5 mm)净化分离,以V(乙腈)∶V(水)=80∶20为流动相,245 nm波长检测,流速0.3 mL/min。结果表明:本法测定的阿维菌素在4 min内可以完全分离,线性范围为0.01~200 mg/L,R2=0.9997,当添加量为0.05、0.5、1.0 mg/kg时,回收率为99.5%~108.1%,RSD为0.30%~1.1%,测定下限为0.005 mg/kg。方法可用于浓缩苹果阿维菌素残留量测定。     

一种可见光成像的目标检测跟踪方法

在末制导成像阶段目标占据视场的大部分面积,形状信息丰富,这时对目标体上某一固定点的稳定跟踪成为最主要的需求。针对图像灰度过于集中目标难于提取的问题,在图像预处理阶段提出了依据概率统计的图像灰度均衡的方法;为解决图像边角点的快速检测问题,提出了图像二维投影和滑动卷积相结合的方法;最终为实现快速稳定的跟踪,提出了依据角点匹配的形心跟踪方法。根据此算法的特点研制了FPGA+DSP的硬件平台,充分利用FPGA的并行流水特性和DSP的逻辑运算特点,能快速检测到目标形心和进行稳定地跟踪,验证了方法的有效性和实用性。此方法应用在某课题上,跟踪效果良好,为试验的圆满成功提供了保障。     

Towards a gravitation theory in Berwald-Finsler space

Finsler geometry is a natural and fundamental generalization of Riemann geometry. The Finsler structure depends on both coordinates and velocities. It is defined as a function on tangent bundle of a manifold. We use the Bianchi identities satisfied by the Chern curvature to set up a gravitation theory in Berwald-Finsler space. The geometric part of the gravitational field equation is nonsymmetric in general. This indicates that the local Lorentz invariance is violated.     

稀土气相扩渗法制备钕-氮化钼及其导电性

过渡金属氮化物因其具有共价固体、离子晶体和过渡金属的综合特性,从而表现出特殊的物理性质和化学性质[1],并具有导电性好,键合强度大、硬度和熔点高等特点,因此比传统的铜、铝及其合金更适合制备电子器件[2,3]。此外其电磁特征类似金属,导电率、霍尔系数、磁化率和热熔都属于金属范围,是一种应用前景良好的导电材料[4￣6]和电极材料[7]。传统的合成方法主要采用金属卤化物、氢化物与氮、氨反应或者金属和氮反应获得相应的金属氮化物[2,8]。在已有的合成方法中,均存在反应时间长,产物中常伴有M o2N、γ鄄M o2N等杂相,不利于应用。稀土气…