一种气象观测数据求导的新方法

气象观测数据不可避免地带有观测误差,而对带有误差的离散数据求导是一个不适定的反问题.为了解决这一长期困扰气象工作者的问题,利用吉洪诺夫正则化思想,提出了矩形区域内观测数据的二维一阶偏导数重构算法.通过系列模拟观测数据试验检验了该算法的性能,表明该算法有效且计算精度高.另外,应用该算法对气象观测资料进行客观分析,结果表明：该算法作为一种新的客观分析方法是可行的,并且还能提高小尺度天气系统的识别能力. 关键词： 数值微分 吉洪诺夫正则化 客观分析     

Design study of an FEL oscillator with a waveguide

We present a design study of a free electron laser （FEL） oscillator for high power THz source experiments on the basis of the Shanghai femtosecond accelerator device. A circular groove guide is used as a new interaction structure. Plane metal meshes are used as upstream and downstream mirrors of the resonator. The general design parameters are presented. We analyzed the spontaneous emission and stimulated emission in the oscillator using these parameters.     

Numerical Simulations of Calcium Ions Spiral Wave in Single Cardiac Myocyte

The calcium ions （Ca^2＋） spark is an elementary Ca^2＋ release event in cardiac myocytes. It is believed to buildup cell-wide Ca^2＋ signals, such as Ca^2＋ transient and Ca^2＋ wave, through a Ca^2＋-induced Ca^2＋ release （CICR） mechanism. Here the excitability of the Ca^2＋ wave in a single cardiac myoeyte is simulated by employing the fire-diffuse-fire model. By modulating the dynamic parameters of Ca^2＋ release and re-uptake channels, we find three Ca^2＋ signaling states in a single cardiac myoeyte： no wave, plane wave, and spiral wave. The period of a spiral wave is variable in the different regimes. This study indicates that the spiral wave or the excitability of the system can be controlled through micro-modulation in a living excitable medium.     

Spiking Behavior in Chua's Circuit

Chua ＇s circuit with a slow-fast effect is established under certain parameter conditions. The dynamics of this slow- fast system is investigated. A spiking phenomenon can be observed in the numerical simulation. By introducing slow-fast analysis and a generalized Jacobian matrix at the non-smooth boundaries, the bifurcation mechanism for the periodic spiking solution, different from the smooth case, is discussed.     

Investigation of the Potts Model on Triangular Lattices by the Second Renormalization of Tensor Network States

We employ the second renormalization group method of tensor-network states to investigate thermodynamic properties of the ferromagnetic and antiferromagnetic Potts model on triangular lattices. From the temperature dependence of the internal energy and the specific heat, both the critical temperatures and critical exponents are evaluated. For the q = 3 antiferromagnetic Potts model, the critical temperature is found to be Tc = 0.627163±0.000003, which is at least one order of magnitude more accurate than that obtained by other methods.     

继承与创新同在,传统与开放并存——2012年浙江省数学高考理科第17题赏析

2012年浙江高考数学理科试卷最后一道填空题,考查的是高中数学中常规、传统的含参数的不等式恒成立问题.2011年浙江高考数学理科试卷最后一道解答题,也是含参数的函数不等式恒成立问题.2011年底全国各种中学数学杂志针对含参数的函数不等式恒成立问题的解     

原子与双模相干强场依赖强度耦合多光子过程中纠缠量度与制备

给出了依赖强度耦合双模多光子过程Jaynes-Cummings模型的有效哈密顿量.在强场条件下,分别用量子约化熵和量子相对熵研究了上述模型中原子与场之间的纠缠以及双模相干场的模间纠缠演化.研究表明,这两类纠缠演化均与原子跃迁时吸收(或发射)的光子数k密切相关.同时,还揭示了双光子过程(k=1)和多光子过程(k≥2)中不同的纠缠特性.讨论了纠缠态的制备,制备了与时间无关的原子-场的Einstein-Podolsky-Rosen态和双模相干场的模间纠缠态.     

光子晶体光纤拉制中工艺参数的控制

分析了光子晶体光纤拉制中各工艺参数之间的相互影响,建立了工艺参数与最终光纤结构之间的对应关系.在温度和送料速度的协调控制下,通过调节气压参数可有效控制气孔结构.实验拉制出孔径孔距比分别为0.45和0.8的单模以及高占空比光子晶体光纤.在制备非均匀孔径光子晶体光纤时,仅靠调控工艺参数往往难以拉制出理想结构,本文以一种单偏振单模PCF结构为例,对预制棒结构进行了优化设计.计算表明可由此拉制出满足要求的光子晶体光纤. 关键词： 光子晶体光纤 工艺参数 气压控制 气孔结构     

一些约束规划问题的近似全局最优解

首先将一个具有多个约束的规划问题转化为一个只有一个约束的规划问题,然后通过利用这个单约束的规划问题,对原来的多约束规划问题提出了一些凸化、凹化的方法,这样这些多约束的规划问题可以被转化为一些凹规划、反凸规划问题．最后,还证明了得到的凹规划和反凸规划的全局最优解就是原问题的近似全局最优解．     

Al-Mg合金中锯齿形屈服现象的热分析

研究了在室温、定加载应变率拉伸的情况下Al-Mg合金中的锯齿形屈服现象.伴随着锯齿形屈服现象的发生,试件表面温度场会发生变化.而红外相机能以较高的时间、空间分辨率记录下随时间变化的试件表面温度场图像.通过分析这些热图像,探讨了A,B两种类型带的传播规律,得到了局域变形带的带宽、倾角、传播速度等特征参数.在此基础上,引入热传导方程,求得了带内的应变率.实验和计算都发现B类型带产生时试件表面带外区域存在弹性收缩现象,由此提出以是否存在带外收缩变形作为划分A,B类型带的新标准.