用自由软件Winplot求解2008高考数学湖北卷部分试题

Winplot是具有计算和绘图功能的一个自由软件,能够根据给出的曲线或曲面方程,直接画图,不需要任何命令.这些特点决定了winplot软件的应用非常广泛.它既能解决中学数学中有关的几何和计算问题,也能解决高等数学中的有关几何和计算问题.……     

Numerical model and experimental demonstration of high precision ablation of pulse CO_2 laser

To reveal the physical mechanism of laser ablation and establish the prediction model for figuring the surface of fused silica, a multi-physical transient numerical model coupled with heat transfer and fluid flow was developed under pulsed CO_2 laser irradiation. The model employed various heat transfer and hydrodynamic boundary and thermomechanical properties for assisting the understanding of the contributions of Marangoni convention,gravitational force, vaporization recoil pressure, and capillary force in the process of laser ablation and better prediction of laser processing. Simulation results indicated that the vaporization recoil pressure dominated the formation of the final ablation profile. The ablation depth increased exponentially with pulse duration and linearly with laser energy after homogenous evaporation. The model was validated by experimental data of pulse CO_2 laser ablation of fused silica. To further investigate laser beam figuring, local ablation by varying the overlap rate and laser energy was conducted, achieving down to 4 nm homogenous ablation depth.     

Damage threshold influenced by polishing imperfection distribution under 355-nm laser irradiation

A systematic interpretation of laser-induced damage in the nanosecond regime is realized with a defect distribution buried inside the redeposited layer arising from a polishing process. Under the 355-nm laser irradiation, the size dependence of the defect embedded in the fused silica can be illustrated through the thermal conduction model. Considering CeO_2 as the major initiator, the size distribution with the power law model is determined from the damage probability statistics. To verify the accuracy of the size distribution, the ion output scaling with depth for the inclusion element is obtained with the secondary ion mass spectrometer. For CeO_2 particulates in size of the depth interval with ion output satisfied in the negative exponential form, the corresponding density is consistent with that of the identical size in the calculated size distribution. This coincidence implies an alternative method for the density analysis of photoactive imperfections within optical components at the semi-quantitative level based on the laser damage tests.     

Caesar密码和Vigenere密码

1 密码学历史简介 密码的设计和使用至少可追溯到四千多年前的古巴比伦、罗马和希腊,历史极为久远.     

用EXCEL解决学费预付问题

1 引言 美国南卡罗林纳学费预付计划(SCTPP)为学生家长提供了预付子女的大学学费的计划,并且保证付款可以完成任何一所南卡罗林纳公立四年制大学的学业.     

中间值法比较形如ab和ba(a＞0,b＞0)幂的不足及解决

人教版高一教材在指数函数这一节内容中涉及有关指数幂大小的比较,这类问题归纳起来主要有三类: 1.同底数,不同指数的幂的比较.这类问题可以通过相应指数函数的单调性来比较; 如:2.13.1＜2.13.2;0.31.4＞0.31.5.     

浅谈平面向量的几何运算及其应用

平面向量的运算包括向量的代数运算与几何运算.相比较而言,学生对向量的代数运算要容易接受一些,但对向量的几何运算往往感到比较困难,无从下手.……