A Multisymplectic Variational Framework for the Nonlinear Elastic Wave Equation

A multisymplectic variational internal energy corresponding equation, its associated local framework for the nonlinear elastic wave equation is presented. The modified to the approximate nonlinea.r elastic wave equation is derived, we obtain the energy and momentum conservation laws as well as the multisymplectic form simultaneously directly from the variational principle     

An Economical Magnetocardiogram System Based on High-To SQUIDs

An economical magnetocardiogram （MCG） system is built in our laboratory. It mainly consists of a MCG data acquisition stage equipped with two high-To superconducting quantum interference device （SQUID） magnetometers, a data processing stage with digital filtering and a one-layer μ-metal magnetically shielded room in conjunction with a high-Tc SQUID based active compensation. Experimental results show that a noise level of pico-tesla in MCG profiles, which is necessary for clinical applications, may be achieved with the system. Moreover, stable and convenient operations of the system are demonstrated with simulating MCG measurements.     

运用反例基于识别的手写数字串分割

采用基于识别的分割方法进行手写数字串分割.在识别的过程中,运用反例样本估计分类器参数,实验数据表明,这种运用反例样本训练的分类器与没有经过反例样本训练的分类器相比,将提高拒识率到19%左右,从而保证了较高的识别率,验证了只有经过反例训练的分类器的输出结果才是可信赖的.     

Pregelation Behaviour of Coagulation Processes with the Constant-Reaction-Number Kernel

We propose an irreversible binary coagulation model with a constant-reaction-number kernel, in which, among all the possible binary coagulation reactions, only p reactions are permitted to take place at every time. By means of the generalized rate equation we investigate the kinetic behaviour of the system with the reaction rate kernel K（i;j） = （ij）^w （0 ≤w〈1/2）, at which an i-mer and a j-mer coagulate together to form a large one. It is found that for such a system there always exists a gelation transition at a finte time to, which is in contrast to the ordinary binary coagulation with the same rate kernel. Moreover, the pre-gelation behaviour of the cluster size distribution near the gelation point falls in a scaling regime and the typical cluster size grows as （to - t）-1/（1-2w）. On the other hand, our model can also provide some predictions for the evolution of the cluster distribution in multicomponent complex networks.     

Compact Single-Stage Femtosecond Multipass Ti：Sapphire Amplifier at 1 kHz with High Beam Quality

A compact femtosecond Ti：sapphire amplifier system is reported using single-stage multipass configuration with high beam quality. A high dispersion glass stretcher and a pair of double prisms for compression are introduced based on broadband femtosecond seed pulses. The non-grating-based pulse stretcher and compressor are advantageous to increase high beam quality and to reduce the high-order dispersion. A Gaussian filter is used to reduce the gain narrowing effect in amplification. The compact femtosecond Ti：sapphire nine-pass amplifier delivers pulses with a duration of 26 fs and an energy of 800μJ at 7mJ pumping pulses energy at I kHz. The 1-kHz femtosecond amplifier with high beam quality and high stability is very suitable for ultrafast physics research applications, such as attosecond science, ultra-precision micromachining, and THz wave generation.     

基于调频信号发射的超声造影剂谐波成像方法

提出了一种能够提取超声造影剂回波中二次谐波的非线性成像方法,从数学原理、仿真计算和声学实验三个方面对造影剂血流灌注成像方法进行了研究。首次将调频信号发射技术用于医学超声造影剂谐波成像领域,仿真计算和声学实验结果表明:为了获得较好的图像质量,发射调频信号应该具有合适的包络;发射信号带宽与解码匹配滤波器带宽之间必须有一个带宽间隔;适当降低发射声压能够降低生物组织的谐波。应用编码发射方法和解码滤波器,得到了造影剂二次谐波图像,此图像具有较好的信号噪声比和造影剂组织比。声学实验结果和理论计算结果完全吻合。     

箱覆盖问题的半定松驰算法

箱覆盖问题是NP困难问题中的经典问题，得到了广泛地研究，九十年代以来，半定松驰策略被用来求解组合优化问题，取得了很好的结果[13]，本文首次给箱覆盖问题的半定松驰算法，算法的理论分析结果表明它适合于求解大规模的箱覆盖问题。     

三维Minkowski空间中的曲面及其可积性

利用可积系统的思想,借助三维Minkowski空间L3的矩阵模型,研究了L3中具有调和逆平均曲率的类空曲面和洛伦兹调和逆平均曲率类时曲面的可积性及其形变.     

巯基乙酸锑配合物的合成与X射线粉末衍射数据指标化

一些锑和铋的配合物可以应用于医药研究[1,2 ] ,已合成了许多锑的有机配体配合物[3～ 7] ,但其中大多数没有生物活性。因此 ,研究锑或铋离子的配合物不仅对主族元素化学、生物无机化学而且对医药都有着非常重要的意义。我们用三氯化锑与巯基乙酸液相反应法合成的二巯基乙酸锑 (Ⅲ)配合物 ,其组成为ＨＳｂ(ＳＣＨ2 ＣＯＯ) 2 ,用Ｘ射线粉末多晶衍射数据指标化来研究配合物晶体结构[8] 。1　实验部分1 1　仪器与试剂ＥＡ - 1 1 0 6型元素分析仪 (意大利卡拉欧巴公司制造 ) ,Ｄ Ｍａｘ -ＹＢ型多晶Ｘ射线粉末衍射仪(日本理学 ,ＣｕＫα射线 ,…     

几种N-取代马来酰胺酸辅酶模型的核磁共振研究

我们对8种N-取代马来酰胺酸辅酶模型与不同类型的亲核试剂反应后生成的产物进行了¹H、¹³C NMR的研究, 测得¹H、¹³C谱化学位移,研 究探讨其规律性, 并测试了IR谱和元素分析.