谈直线和二次曲线教学的几点尝试

毫不过分地说，直线和二次曲线是中专数学中极其重要的一部分内容．讲好这两章，对学生较深刻地理解解析几何的思想内涵和理论方法、对培养学生辩证唯物主义观点和分析解决数学问题能力，对学生学好微积分等是至关重要的．为此，我们在教材处理上和教学实践中做了如下尝试...     

酶动力学的图形理论——定态反应体系

在酶动力学中采用图形方法,能够直接把计算规则和表征反应体系的图形联系起来,这不仅使计算较为直观和方便,且有助于对反应体系的分析与讨论. 本文分析了目前国际上在酶动力学中所采用的图形计算方法,指出其缺陷所在.然后提出一套新的酶动力学的图形计算方法,包含三个法则.法则1有助于纠正现有方法在计算时常易出现的一些差错. 法则2和法则3则分别为计算含酶物浓度的分子和分母提供了新的图形方法,可用来处理较复杂的酶反应体系。 在附录中,还给出了这三个法则的数学原理。     

阴极溶出伏安法测定人发中微量硒

近年来,测定人发中微量硒的方法,已见报道。本文对(NH_4)_2SO_4-CuCl_2-EDTA体系测硒的方法进行了改进。结果表明:在(NH_4)_2SO_4-CuCl_2-NiSO_4-EDTA体系中以阴极溶出伏安法测定微量硒,与原法相比,提高了测定灵敏度,改善了电极性能,使所测得的峰形及结果重现性都有明显改善。将此法用于人发样品中微量硒测定,结果令人满意。     

大型非对称线性方程组的分块直接解法

大型拟带形对称正定线性方程组的分块直接解法已获得广泛应用,而将这方法推广到大型拟带形非对称非奇方程组时需要解决两个关键问题:第一,推广相关三角块的概念,并有效地使用它,以使分块直接解法的内外存交换次数尽可能少;第二,应用消去法于非对称块时主元的处理,要求既不破坏原矩阵的拟带形,又能使算法得以     

Solving Large Sparse Linear and Quadratic Generalized Eigenvalue Problems

We study the methods for solving the following large order eigenvelue problems occurring in the analysis of structural vibration: (1) (2) and (3) where M and C are both symmetric matrices, while (?) is skew symmetric. Moreover, M is positive definite, and the matrix K in (2) and (3) is also assumed to be symmetric positive definite. 1 The eigenvalue problem for normal matrices in generalized inner prduct Let B be an n×n Hermitian positive definite matrix. Then     

Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

铝板中Lamb波检测的实验研究

Lamb波在传播过程中具有频散及多模态特性,若相关参数选择不当,会导致在实际应用中信号相互叠加而无法识别。本文基于Lamb波的频散曲线是其频散方程实数解分布的特点,采用二分法绘制了铝板中Lamb波的频散曲线、波结构曲线和入射角曲线。根据曲线选择S0模态的Lamb波对1mm厚铝板中不同类型的缺陷进行检测。实验结果表明,S0模态的Lamb波对裂纹型缺陷和贯穿型缺陷十分敏感,但对于裂纹型缺陷,其幅值变化并不与缺陷大小成线性关系,并且S0模态Lamb波的声场指向性十分集中,在偏离声束轴线时无法检测到缺陷。     

Three-dimensional solitons in two-component Bose-Einstein condensates

We investigate a kind of solitons in the two-component Bose-Einstein condensates with axisymmetric configurations in the R2 × S1 space. The corresponding topological structure is referred to as Hopfion. The spin texture differs from the conventional three-dimensional （3D） skyrmion and knot, which is characterized by two homotopy invariants. The stability of the Hopfion is verified numerically by evolving the Gross-Pitaevskii equations in imaginary time.     

A theoretical extraction scheme of transport information based on exclusion models

In order to explore how to extract more transport information from current fluctuation,a theoretical extraction scheme is presented in a single barrier structure based on exclusion models,which include counter-flows model and tunnel model.The first four cumulants of these two exclusion models are computed in a single barrier structure,and their characteristics are obtained.A scheme with the help of the first three cumulants is devised to check a transport process to follow the counter-flows model,the tunnel model or neither of them.Time series generated by Monte Carlo techniques is adopted to validate the abstraction procedure,and the result is reasonable.     

基于集合经验模态分解-小波阈值方法的爆破振动信号降噪方法

为了更好地消除混杂在爆破信号中的噪声,引入一种基于集合经验模态分解和小波阈值共同作用的降噪方法。首先将信号进行集合经验模态分解,然后选择含噪的模态函数分量进行小波阈值降噪处理,最后把处理后的分量和未处理的分量进行叠加,重构的信号即为降噪信号。该方法不仅能有效的去除噪声,还能使爆破波形保留其真实性和完整性。