定积分概念的创新教学尝试

介绍了在讲授定积分概念中的一系列创新做法.通过对定积分概念课的优化设计,达到理解概念、掌握方法、培养能力的目的.     

Cu^2＋—酪氨酸络合过程的ESR研究

本文利用室温ESR方法考察了不同配比的Cu~(2+)-酪氨酸水溶液在不同pH值下形成络合物的过程。结果表明溶液pH值及酪氨酸的相对浓度越大,越有利于稳定络合物的生成。     

镧石型碳酸钕的形成及晶种对结晶的促进作用

The characteristics of pH value variation during aging process of amorphous neodymium carbonate formed by three different feeding manners have been investigated. The promotion action of seeding on the crystallization of neodymium carbonate is discussed. X-ray diffraction pattern and the elemental analysis results show that neodymium carbonate can transfer from amorphous to crystalline normal neodymium carbonate Nd₂(CO₃)₃·8H₂O with lanthanide structure at room temperature. Its crystallization activity zone lies in lower feeding ratio area expressed by n_NH4HCO3/n_NdCl3 between 2～3. The existing of seeds can shorten crystalline time, from more than 15 h without seed to 2 h with seeds under normal feeding manner. And the spontaneity nucleation time can be shortened further when feeding with multi-steps normal manner. However, whether multi-steps normal or synchronously and continuously feeding manner, the precipitate formed can transfer to crystalline neodymium carbonate directly under seeding. At the same time, it is observed that the variation of pH value reduces with the decrease of feeding amount and the shortening of aging period, indicating that with synchronously and continuously feeding manner can not only realize fast crystallization, but also control pH value within a narrow range, which is beneficial for the producing of neodymium carbonate crystal with narrow-distributed particle size and monitoring of its crystallization process.     

一种由La2O3水化制备棒状La（OH）3的简便方法

通过本体氧化物在常压沸腾水中的水化处理制备了具有棒状外型的氢氧化镧。XRD衍射图显示在短时间内可以得到六方相氢氧化镧，表明其水化过程是相当快的。所得氢氧化镧几乎完全呈针状和棒状外型，其宽度为2-3μm，长为5-8μm。对棒状氢氧化镧的形成机制作了适当解释，并通过煅烧该氢氧化镧微米棒得到了类似外形的氧化镧。该方法比水热法更易于实现工业化应用。     

木炭具有吸附作用实验的改进

一、实验装置实验装置如下右图。二、实验步骤 1.在烧杯里装入蓝色的硝酸铜溶液,在锥形瓶中充满黄绿色的氯气,塞上单孔橡皮塞。 2.取几小块木炭放在坩埚中烘烤一下,以便赶走木炭多孔缝隙中的空气,使其有更好的吸附作用,待木炭冷却后,立即投入锥形瓶中,紧塞橡皮塞,轻轻振荡锥形瓶,使氯气和木炭充分接触,就能看到锥形瓶里的     

氧化锌表面包覆Sn_6O_4(OH)_4的制备及其在锌镍电池中的应用

采用水热-共沉淀法在氧化锌表面包覆锡化合物,利用扫描电子显微镜(SEM)、X射线衍射(XRD)和能谱分析(EDS)对制备的包覆ZnO材料进行表征。结果表明:XRD表明附着在氧化锌表面的是Sn_6O_4(OH)_4,且结晶度较好;SEM测试显示在p H=12条件下,Sn_6O_4(OH)_4能够很好地附着在氧化锌颗粒表面;EDS显示组成物中的元素包含Zn、Sn、O三种元素。利用循环伏安曲线(CV)、电化学阻抗谱(EIS)、倍率充放电技术对包覆ZnO材料进行了电化学性能的测试,结果表明:包覆Sn_6O_4(OH)_4的ZnO可以提高锌负极的耐蚀性能,增大电荷转移电阻(Rct);锌电极覆Sn_6O_4(OH)_4量为3%时充放电效率最佳,在0.2C充放循环40次后充放电循环保持率仍有70%。     

Novel Woods-Saxon stochastic resonance system for weak signal detection

We propose a joint exponential function and Woods–Saxon stochastic resonance(EWSSR)model.Because change of a single parameter in the classical stochastic resonance model may cause a great change in the shape of the potential function,it is difficult to obtain the optimal output signal-to-noise ratio by adjusting one parameter.In the novel system,the influence of different parameters on the shape of the potential function has its own emphasis,making it easier for us to adjust the shape of the potential function.The system can obtain different widths of the potential well or barrier height by adjusting one of these parameters,so that the system can match different types of input signals adaptively.By adjusting the system parameters,the potential function model can be transformed between the bistable model and the monostable model.The potential function of EWSSR has richer shapes and geometric characteristics.The effects of parameters,such as the height of the barrier and the width of the potential well,on SNR are studied,and a set of relatively optimal parameters are determined.Moreover,the EWSSR model is compared with other classical stochastic resonance models.Numerical experiments show that the proposed EWSSR model has higher SNR and better noise immunity than other classical stochastic resonance models.Simultaneously,the EWSSR model is applied to the detection of actual bearing fault signals,and the detection effect is also superior to other models.     

混合团簇Cu11Fe2的的密度泛函研究

以Cu13非紧致低对称性基态结构及四种13原子高对称性（Ih、Oh、D5h、D3h）密堆积结构为初始构型,通过不等价位原子替换,利用密度泛函理论系统研究了Cu11Fe2混合团簇的稳定性及磁性．结果表明：对四种高对称性结构相应中心位替代构型稳定性均高于双表面位替代构型;Cu11Fe2团簇的基态结构为含一个中心位替代和一个表面位替代的Ih替换结构,这与Cu13的基态结构完全不同;Cu11Fe2无明显近基态同分异构现象;相较Cu13团簇、Cu11Fe2团簇的稳定性及磁性均得到增强．     

A parallel algorithm for generating multiple ordering spanning trees in undirected weighted graphs

1.IntroductionLetG=(V,E,W)beaconnected,weightedandundirectedgraph,VeEE,w(e)(相似文献