2,6-二甲基-3,5-二(吡唑-3-基)吡啶/铜构筑的一维链状Keggin型杂多酸盐的合成、结构及电化学性质研究

以二水氯化铜(CuCl2·2H2O)、硅酸钠(Na2SiO3)、钼酸钠(Na2 MoO4)和2,6-二甲基-3,5-二(吡唑-3-基)吡啶(简写为H2L)为原料,通过水热反应,成功地合成了一个一维链状Keggin型多酸基杂化化合物[Cu2(H3L)2](SiMo12O40).通过X-射线单晶衍射、TGA、IR以及元素分析对该化合物的结构进行表征.测试结果表明,该化合物属于三斜晶系,P-1空间群,晶胞参数a=1.1689(5) nm,b=1.2157(5) nm,c=1.2233(5) nm,α=62.066(5)°,β=62.833(5)°,γ =74.789(5)°,V=1.363 8(10) nm3,Z=2,R1=0.082 4,wR2=0.174 5.电化学分析结果表明该化合物对亚硝酸盐的还原具有良好的电催化效果.     

基于Nie-Tan算法的区间二型模糊集质心计算:改变主变量采样个数

计算区间二型模糊集的质心(也称降型)是区间二型模糊逻辑系统中的一个重要模块。Karnik-Mendel(KM)迭代算法通常被认为是计算区间二型模糊集质心的标准算法。尽管如此,KM算法涉及复杂的计算过程,不利于实时应用。在各种改进类算法中,非迭代的Nie-Tan(NT)算法可节省计算消耗。此外,连续版本NT(CNT,continuous version of NT)算法被证明是计算质心的准确算法。本文比较了离散版本NT算法中求和运算和连续版本NT算法中求积分运算,通过四个计算机仿真例子证实了当适度增加区间二型模糊集主变量采样个数时,NT算法的计算结果可以精确地逼近CNT算法。     

低喷淋密度超亲水表面水平管降液膜温度分布

水平管降液膜蒸发广泛应用在石油、化工、海水淡化等领域,对低喷淋密度温度演化规律的研究有助于拓宽其应用范围,理解其微观机理。本文在超亲水表面上结合红外热追踪技术,对水平管降液膜表面的温度演化规律进行了研究,分析了温度分区现象和温升规律。实验中首次发现了马鞍形液膜内部的高温环状结构,并结合三维数值模拟揭示了掺混作用导致的局部高温环状结构形成的内部机理。     

EAST装置上W波段多道极向相关反射仪的研制

在EAST装置上安装了X模极化W波段多道相关反射仪，用于测量等离子体芯部密度涨落。该诊断利用低损耗(<3dB)多工器将4个不同频率(79.2GHz，85.2GHz，91.8GHz和96GHz)的微波耦合在一起，通过同一个天线发射。反射波由两个极向分离(~5cm)的天线接收，通过下变频技术实现外差测量。通过对两个极向天线接收的信号进行相关分析，获得芯部湍流垂直速度。对2018年低约束模式(L模)放电进行分析发现，在电子回旋共振加热(ECRH)等离子体中，芯部湍流垂直速度在电子逆磁漂移方向。而在注入同向中性束(co-NBI)后，芯部湍流垂直速度变为离子逆磁漂移方向。     

OCS经由F 31Π里德堡态生成CO(X1Σ+)+S(1D2)产物的波长相关性光解离

本文利用时间切片离子速度成像技术在134∽140 nm波段研究了OCS分子经由F 3¹Π里德堡态的真空紫外光解离动力学. 在选取的5个分别对应OCS(F 3¹Π, v₁=0∽4)的伸缩振动激发的光解波长，实验测得了来自CO(X¹Σ⁺)+S(¹D₂)产物通道的SS(¹D₂))实验影像，并获得了总平动能谱和CO(X¹Σ⁺, v)共生产物的振动布居及角分布. 结果分析表明OCS分子解离生成CO(X¹Σ⁺)+S(¹D₂)产物的过程经历了上态F 3¹Π 与C_?v和C_s构型的下电子态间非绝热耦合过程. 实验结果显示了很强的波长相关性：OCS (F 3¹Π, v₁)的较低转动激发态(v₁=0∽2)和较高转动激发态(v₁=3, 4)的CO(X¹Σ⁺)产物的振动布居和角分布具有显著差异，表明该解离过程中具有不同的解离机理. 本结果提供了振动耦合可能对真空紫外光解离动力学产生关键作用的相关证据.     

光纤布拉格光栅传感器应变传递双向耦合分析

粘贴于受弯基体表面的光纤布拉格光栅传感器测量应变与基体真实应变之间存在误差,因此研究光纤布拉格光栅传感器的变形机理、分析测量应变与真实应变之间的关系是目前的研究热点.首先研究光纤布拉格光栅传感器与基体之间的相互作用机理,然后,利用有限元解、实验值和理论解进行对比验证,并分析产生误差的原因.最后,通过参数分析研究弹性模量、厚度、粘结长度等参数对光纤布拉格光栅传感器测量效果的影响.结果表明有限元解、实验值和理论解具有相同的变化趋势,有限元解与理论解的误差在2%以内,测量值与理论解的误差在7%以内.平均应变传递率随着基体弹性模量的增大、粘结长度的增长而逐渐增大,随粘结层弹性模量的减小、粘结层厚度的增大而逐渐减小.该理论对应用于受弯基体应变测量的光纤布拉格光栅传感器的设计具有一定的指导意义.     

A conditional symmetric memristive system with amplitude and frequency control

By introducing a memristor into a chaotic system with a single non-quadratic term and substituting an absolute value function for conditional symmetry, a unique chaotic system is constructed. Firstly, the system shares a special structure of symmetry and conditional symmetry. Secondly, the amplitude and frequency of the system variables can be rescaled by the applied memristor. Interestingly it gives a new case of attractor control namely partial amplitude control and global frequency control. At last, as a new regime of extreme multistability, the memristive system shows relatively simple bifurcation according to the initial condition. This new class of chaotic system has never been reported to the best of our knowledge.

     

Surface passivation in n-type silicon and its application in silicon drift detector

Based on the surface passivation of n-type silicon in a silicon drift detector(SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-silicon(NAOS)method has good compactness and simple process, the first layer film is formed by the NAOS method. The Al2O3 film is also introduced into the passivation stacks owing to exceptional advantages such as good interface characteristic and simple process. In addition, for requirements of thickness and deposition temperature, the third layer of the SiO2 film is deposited by plasma enhanced chemical vapor deposition(PECVD). The deposition of the SiO2 film by PECVD is a low-temperature process and has a high deposition rate, which causes little damage to the device and makes the SiO2 film very suitable for serving as the third passivation layer. The passivation approach of stacks can saturate dangling bonds at the interface between stacks and the silicon substrate, and provide positive charge to optimize the field passivation of the n-type substrate.The passivation method ultimately achieves a good combination of chemical and field passivations. Experimental results show that with the passivation structure of SiO2/Al2O3/SiO2, the final minority carrier lifetime reaches 5223 μs at injection of 5×10¹⁵ cm^-3. When it is applied to the passivation of SDD, the leakage current is reduced to the order of nA.     

碳纳米管的可控长度拾取及导电性分析

拾取指定长度的半导体性碳纳米管对大规模制造碳纳米管场效应管具有重要意义.本文提出了一种利用原子力显微镜探针和钨针对碳纳米管进行可控长度拾取的方法并进行了碳纳米管导电性分析.在扫描电子显微镜下搭建微纳操作系统,针对切割操作过程中原子力显微镜探针、钨针和碳纳米管的接触情况进行了力学建模和拾取长度误差分析.建立了单根金属性碳纳米管、单根半导体性碳纳米管及碳纳米管束与钨针接触的电路模型,推导了接入不同性质碳纳米管后电路的电流电压特性方程.使用原子力显微镜探针对碳纳米管的空间位姿进行调整,控制钨针对碳纳米管上目标位置进行通电切割,同时获取切割电路中的电流电压数据.实验结果表明,本文提出的方法能够有效控制所拾取碳纳米管的长度,增加碳纳米管与原子力显微镜探针的水平接触长度能够减小碳纳米管形变导致的拾取长度误差,建立的电流电压特性方程能够用于分析碳纳米管的导电性.     

Enantioselective Copper‐Catalyzed Azide–Alkyne Click Cycloaddition to Desymmetrization of Maleimide‐Based Bis(alkynes)

A copper catalyst system derived from TaoPhos and CuF₂ was used successfully for catalytic asymmetric Huisgen [3+2] cycloaddition of azides and alkynes to give optically pure products containing succinimide‐ and triazole‐substituted quaternary carbon stereogenic centers. The desired products were obtained in good yields (60–80 %) and 85:15 to >99:1 enantiomeric ratio (e.r.) in this click cycloaddition reaction.