稀土元素在含残余砷、锡09Cr2AlMoRE钢中的作用

对加稀土前后09Cr2AlMoRE钢取样分析化学成分,制备金相样用SEM-EDS研究了钢中析出物特征,制备透射电镜(TEM)试样通过TEM研究元素的晶界偏聚,并用热力学计算了稀土Ce,La,S和残余元素As反应固定残余元素As的可能性。研究结果表明:在低氧、硫的条件下,稀土镧可以和09Cr2AlMoRE钢中较低含量的砷(130×10-6)作用生成镧砷金属间化合物;铈、镧主要是通过形成稀土砷硫夹杂物固定钢中残余元素砷。另外,在本实验条件下稀土元素(64×10-6)只有很微量的偏聚在晶界,残余元素As不在晶界偏聚。     

用于直接甲醇燃料电池的侧链型磺化聚芳醚酮/聚乙烯醇交联膜的制备与性能研究

以高磺化度的侧链型磺化聚芳醚酮(S-SPAEK)和聚乙烯醇(PVA)为原料,通过溶液共混的方法在120℃下制备了PVA含量不同的S-SPAEK/PVA交联膜.红外光谱图表明S-SPAEK聚合物中的磺酸基团与PVA中的羟基反应生成酯键而形成共价交联.通过对交联膜的性能测试发现PVA的引入明显降低了膜的甲醇渗透系数,改善了膜的溶胀性,提高了膜的保水能力.S-SPAEK/PVA(85/15)交联膜水的脱附系数从S-SPAEK的3.1×10-8 cm2/s降低到2.9×10-9 cm2/s.在25℃和60℃时S-SPAEK/PVA(85/15)交联膜的甲醇渗透系数分别为2.6×10-7cm2/s和3.9×10-7cm2/s,明显低于相同温度下的纯S-SPAEK膜的8.1×10-7cm2/s与14.5×10-7cm2/s,而其质子传导率虽然有所下降,但是在25℃和80℃时分别达到了0.055 S/cm和0.083 S/cm,能够满足直接甲醇燃料电池(DMFCs)对质子交换膜的要求,有望在DMFCs中得到应用.     

3，5-二硝基苯甲酸镉配合物的合成、晶体结构、热稳定性和荧光性质

以3,5-二硝基苯甲酸,咪唑为配体,合成了新化合物[Cd(H₂O)₂(DNBA)(Im)₂](DNBA)·H₂O,(DNBA=3,5-二硝基苯甲酸阴离子)。该配合物属正交晶系,空间群为Ccc2,晶胞参数：a=1.324 99(4) nm,b=1.516 01(5) nm,c=2.789 22(8) nm;V=5.602 7(3) nm³,D_c=1.719 g·cm^-3,Z=8,μ=0.866 mm^-1,F(000)=2 912,最终偏离因子R₁=0.058 3,wR₂=0.146 4。该配合物中包含两个单核镉(Ⅱ)配合物,且配合物中还包含未配位的3,5-二硝基苯甲酸,金属中心均是六配位变形八面体结构。并测定和研究了标题化合物的热重和荧光性能。     

基于RFID的智能跟踪机器人的设计

针对国内各种智能机器人的智能跟踪难这一现状,设计出一种基于RFID技术的智能跟踪的机器人,能实现对携有特定电子标签的目标进行实时跟踪。该机器人以STC89C51单片机为核心,采用有源RFID读写器(HR6020C)和电子标签(WS-HT06)构建定位系统,采用单片机控制L298来驱动机器人的两个后轮,整个系统通过单片机进行整合、计算、处理数据,并发出指令,控制机器人对目标进行跟踪,进而达到机器人的智能跟踪的目的。实验结果表明,该机器人达到了智能跟踪的要求。     

具有变时滞和马尔可夫切换的随机递归神经网络的弱收敛(英文)

本文研究了具有变时滞和马尔可夫切换的随机递归神经网络的弱收敛,通过运用Lyapunov函数、随机分析技巧和推广了的Halanay不等式,得到了上述模型为弱收敛的充分性条件,并且我们揭示了对上述递归神经网络模型所确定的segment过程的转移概率的极限分布是此模型的解过程的唯一的遍历不变概率测度.此外,我们还给出了例子和数值模拟来说明我们结论的正确性.     

二维柱坐标系辐射输运方程保球对称的离散纵标格式

 离散纵标格式是计算辐射输运方程的常用格式之一. 但是, 传统的离散纵标格式求解二维柱坐标系辐射输运方程模拟一维球对称问题时, 会出现明显的非对称现象, 球对称性被破坏. 针对该问题, 本文分析了传统离散纵标格式不能够保持球对称性的原因, 提出了空间基于柱坐标系、方向基于球坐标系的辐射输运方程, 并对该方程设计了新的离散纵标格式, 从理论上证明了当空间网格取球对称剖分时该离散格式能够保持一维球对称性的充分必要条件. 通过对真空球区域辐射输运、与物质耦合辐射输运等球对称算例的数值模拟, 验证了该格式的保球对称性, 球对称误差能够达到机器精度. 非对称辐射驱动模型以及非对称网格剖分条件下的数值模拟等算例也取得了较好的结果.     

Edge Flips in Surface Meshes

Little theoretical work has been done on edge flips in surface meshes despite their popular usage in graphics and solid modeling to improve mesh equality. We propose the class of \((\varepsilon ,\alpha )\)-meshes of a surface that satisfy several properties: the vertex set is an \(\varepsilon \)-sample of the surface, the triangle angles are no smaller than a constant \(\alpha \), some triangle has a good normal, and the mesh is homeomorphic to the surface. We believe that many surface meshes encountered in practice are \((\varepsilon ,\alpha )\)-meshes or close to being one. We prove that flipping the appropriate edges can smooth a dense \((\varepsilon ,\alpha )\)-mesh by making the triangle normals better approximations of the surface normals and the dihedral angles closer to \(\pi \). Moreover, the edge flips can be performed in time linear in the number of vertices. This helps to explain the effectiveness of edge flips as observed in practice and in our experiments. A corollary of our techniques is that, in \(\mathbb {R}^2\), every triangulation with a constant lower bound on the angles can be flipped in linear time to the Delaunay triangulation.     

Water-soluble pillar[6]arene stabilized silver nanoparticles: preparation and application in amino acid detection

In the presence of a water-soluble pillar[6]arene WP6 containing 12 imidazolium groups, silver nanoparticles were successfully prepared and investigated in detail by ultraviolet visible spectroscopy, X-ray diffraction, and transmission electron microscopy. Excitingly, these pillar[6]arene stabilized silver nanoparticles were demonstrated to function as a colorimetric sensor to selectively probe glutamic acid in water.     

Enantioselective sulfenylation of α-nitroesters catalyzed by diarylprolinols

The organocatalytic sulfenylation of α-nitroesters mediated by diaryl-l-prolinols was developed. A range of α-sulfenylated α-nitroesters were obtained in good yields with moderate to good enantioselectivities.