A Hermitian Box-scheme for One-dimensional Elliptic Equations – Application to Problems with High Contrasts in the Ellipticity

We introduce a new box-scheme, called ``hermitian box-scheme' on the model of the one-dimensional Poisson problem. The scheme combines features of the box-scheme of Keller, [20], [13], with the hermitian approximation of the gradient on a compact stencil, which is characteristic of compact schemes, [9], [21]. The resulting scheme is proved to be 4th order accurate for the primitive unknown u and its gradient p. The proved convergence rate is 1.5 for (u,p) in the discrete L ² norm. The connection with a non standard mixed finite element method is given. Finally, numerical results are displayed on pertinent 1-D elliptic problems with high contrasts in the ellipticity, showing in practice convergence rates ranging from 1 to 2.5 in the discrete H ¹ norm. This work has been performed with the support of the GDR MOMAS, (ANDRA, CEA, EDF, BRGM and CNRS): Modélisation pour le stockage des déchets radioactifs. The author thanks especially A. Bourgeat for his encouragements and his interest in this work.     

Optimal estimation of parameters of dynamical systems by neural network collocation method

In this paper we propose a new method to estimate parameters of a dynamical system from observation data on the basis of a neural network collocation method. We construct an object function consisting of squared residuals of dynamical model equations at collocation points and squared deviations of the observations from their corresponding computed values. The neural network is then trained by optimizing the object function.The proposed method is demonstrated by performing several numerical experiments for the optimal estimates of parameters for two different nonlinear systems. Firstly, we consider the weakly and highly nonlinear cases of the Lorenz model and apply the method to estimate the optimum values of parameters for the two cases under various conditions. Then we apply it to estimate the parameters of one-dimensional oscillator with nonlinear damping and restoring terms representing the nonlinear ship roll motion under various conditions. Satisfactory results have been obtained for both the problems.     

钻井泵阀箱密封面CO2堆焊试验研究及应用

介绍了用CO_2堆焊35CrMo钢钻井泵阀箱密封面磨损修复工作,通过试验表明,采用Φ1.2mm的H08Mn2Si焊丝,以短路过渡CO_2焊法施焊,可以获得致密、耐磨的堆焊金属层。该法已成功地用于生产,取得了良好的经济效益。     

UniMAT PLC在塑料挤出机控制系统中的应用

针对塑料挤出机控制系统成本高、速度低、精度低的问题,提出采用UniMATPLC控制方式,实践证明效果良好。     

钛合金中亚晶的电子显微镜观察

用透射电子显微镜观察了TC6钛合金在高温退火过程中形成的亚晶(Subgrain)。合金经850℃,920℃退火后炉冷和空冷,在初生α相晶粒内形成亚晶,多为成簇分布的狭长形状,亚晶的数量随退火后冷却速度的增加而减少。亚晶界(Subgrain boundary)是由位错构成的,亚晶的形成是多边化(polygonization)的结果。     

TC11钛合金中氧铝偏析与脆性断裂

借助ＳＥＭ及ＥＤＡＸ、ＡＥＳ对某些ＴＣ１１钛合金棒材机械性能差的原因进行了研究。。结果表明材料延伸率、断面收缩率及冲击值低，显微硬度值高的拉伸和冲击断口上都呈现脆性解理断裂的断裂源，源区显微组织为条状α及空洞，且氧铝偏高。氧铝偏高造成α＋β→β相变温度和再结晶温度升高，使加工变形中形成的条状α在随后的热处理中得不到改变，并导致拉伸、冲击时的脆性断裂     

35CrMo齿轮轴探伤解剖定性

在35CrMo齿轮轴轴身最大直径部位取片进行了低倍解剖定性。结果表明,锻件内部夹杂物数量特别多,还有微裂纹和白点缺陷,因此缺陷性质被定为夹杂和白点。     

4-(6′甲基苯并噻唑-2′-偶氮)-3,5-二氨基吡唑与钯显色反应的研究和应用

对6种苯并噻唑偶氮吡唑化合物的分析特性进行了探讨,着重研究了4—(6′—甲基苯并噻唑-2′-偶氮)-3,5-二氨基吡唑(MBTAP)与钯离子显色反应的光度性质。在非离子表面活性剂 Brij35存在下与钯离子形成橙红色的配合物。适宜的 pH 值范围为9.0～10.5.配合物的最大吸收波长为510nm,表观摩尔吸光系数为3.01×10~4L·mol~(-1)·cm~(-1)。钯在0～14μg/25mL,范围内服从比尔定律.显色体系可稳定11h。在柠檬酸存在下可消除 Fe~(3+)、Co~(2+)、Cu~(2+)、Ni~(2+)等离子的干扰。     

基于GSM网络的汽车防盗系统研制

以STC89C52单片机和西门子公司的TC35I GSM模块为核心,设计了以手机短信实时监控汽车状态的防盗系统,实现了汽车的无线监控.