2，2′-联喹啉-4，4′-二羧酸构筑的一维钴(Ⅱ)配位聚合物

利用2,2′-联喹啉-4,4′-二羧酸钠(Na2bqdc),2,2-联吡啶与硫酸钴在溶剂热作用下合成了1个一维配位聚合物[Co(bqdc)(bipy)(H2O)]n(1)。通过元素分析、粉末衍射、红外、紫外光谱对配合物进行了表征,利用X射线单晶衍射仪测定了其晶体结构。中心CoⅡ离子分别与2个来自2,2-联喹啉-4,4-二羧酸钠配体的双齿羧基氧原子和1个来自配体的单齿羧基氧原子、辅助配体2,2-联吡啶上的2个N原子和1个水分子的氧原子配位,形成了1个稍微扭曲的八面体配位构型。紫外光谱实验表明,相对2,2′-联喹啉-4,4′-二羧酸钠配体,配合物的紫外光谱发生了少量的蓝移。对该配合物多晶样品的差热分析(TGA)表明该化合物在217℃后开始分解。     

叠氮桥联四氮杂十四环席夫碱双核铜(Ⅱ)配合物[Cu_2~(2+)(C_(32)H_(64)N_8N_3~-)]_2(ClO_4~-)_6·H_2O的合成与表征

用丙酮和乙二胺在高氯酸催化下合成了四氮杂十四元环席夫碱(1),并用1与碱式碳酸铜和叠氮化钠反应,生成铜的双核大环配合物。通过X-射线单晶衍射和红外光谱对其进行了结构表征。该配合物属单斜晶系,P2(1)空间群,晶胞参数为a=0.93214(8)nm,b=2.03665(17)nm,c=2.6540(2)nm;β=99.6590(10)°;V=4.9670(7)nm3,Z=2,Dc=1.387mg/m3,Mr=2074.76,F(000)=2172,最终R=0.0557,wR=0.1241。该配合物包括2个不对称的双核结构、6个高氯酸根和1个水分子。每一个双核结构中的铜原子都是五配位,它们分别和大环配体上的4个氮原子及叠氮根两端的氮原子配位形成畸变的四方锥构型。     

试用聚类分析对船只噪声和脑电分类

聚类分析属模式识别的一种方法,不同样本由于其信息特征有差异,经信号处理与计算机学习,可以在减维的特征空间被分类识别。本文介绍用非线性映射减维变换的方法,对船只噪声和脑电进行分类识别,想通过对两种不同领域里的样本试分类,来说明聚类分析方法的广泛适用性。     

The effect of a HfO2 insulator on the improvement of breakdown voltage in field-plated GaN-based HEMT

A GaN/Al_0.3Ga_0.7N/AlN/GaN high-electron mobility transistor utilizing a field plate (with a 0.3 μm overhang towards the drain and a 0.2 μm overhang towards the source) over a 165-nm sputtered HfO₂ insulator (HfO₂-FP-HEMT) is fabricated on a sapphire substrate. Compared with the conventional field-plated HEMT, which has the same geometric structure but uses a 60-nm SiN insulator beneath the field plate (SiN-FP-HEMT), the HfO₂-FP-HEMT exhibits a significant improvement of the breakdown voltage (up to 181 V) as well as a record field-plate efficiency (up to 276 V/μm). This is because the HfO₂ insulator can further improve the modulation of the field plate on the electric field distribution in the device channel, which is proved by the numerical simulation results. Based on the simulation results, a novel approach named the proportional design is proposed to predict the optimal dielectric thickness beneath the field plate. It can simplify the field-plated HEMT design significantly.     

Development and characteristic analysis of a field-plated Al2O3/AlInN/GaN MOS–HEMT

We present an AlInN/AlN/GaN MOS–HEMT with a 3 nm ultra-thin atomic layer deposition (ALD) Al₂O₃ dielectric layer and a 0.3 μm field-plate (FP)-MOS--HEMT. Compared with a conventional AlInN/AlN/GaN HEMT (HEMT) with the same dimensions, a FP-MOS--HEMT with a 0.6 μm gate length exhibits an improved maximum drain current of 1141 mA/mm, an improved peak extrinsic transconductance of 325 mS/mm and effective suppression of gate leakage in both the reverse direction (by about one order of magnitude) and the forward direction (by more than two orders of magnitude). Moreover, the peak extrinsic transconductance of the FP-MOS--HEMT is slightly larger than that of the HEMT, indicating an exciting improvement of transconductance performance. The sharp transition from depletion to accumulation in the capacitance--voltage (C--V) curve of the FP-MOS--HEMT demonstrates a high-quality interface of Al₂O₃/AlInN. In addition, a large off-state breakdown voltage of 133 V, a high field-plate efficiency of 170 V/μ m and a negligible double-pulse current collapse is achieved in the FP-MOS--HEMT. This is attributed to the adoption of an ultra-thin Al₂O₃ gate dielectric and also of a field-plate on the dielectric of an appropriate thickness. The results show a great potential application of the ultra-thin ALD-Al₂O₃ FP-MOS--HEMT to deliver high currents and power densities in high power microwave technologies.     

溶胶-凝胶法合成KGd(WO4)2:Eu3+红色荧光粉及其发光性质的研究

采用溶胶-凝胶法合成KGd(WO4)2:Eu3+红色荧光粉.该荧光粉的性质通过X射线粉末衍射、扫描电子显微镜、激发谱、发射谱以及荧光衰减曲线来表征.KGd(WO4)2:Eu3+的激发谱主要由中心大约在270nm处的宽谱峰以及一系列由Eu3+离子f-f电子能级跃迁导致的锐线峰组成,在近紫外区有一个最强的激发峰在395nm.正好与紫外InGaN发光二极管(LED)芯片发射波长匹配.在395nm激发下,可以观察到最佳掺杂量为40%(原子分数)的KGd(WO4)2:Eu3+在614nm处产生强烈的红光.发光特性表明,KGd(WO4)2:Eu3+荧光粉可能潜在成为近紫外发光二极管(LEDs)用的红色荧光粉.     

A method of generating random bits by using electronic bipolar memristor

The intrinsic stochasticity of resistance switching process is one of the holdblocks for using memristor as a fundamental element in the next-generation nonvolatile memory.However,such a weakness can be used as an asset for generating the random bits,which is valuable in a hardware security system.In this work,a forming-free electronic bipolar Pt/Ti/Ta2O5/Pt memristor is successfully fabricated to investigate the merits of generating random bits in such a device.The resistance switching mechanism of the fabricated device is ascribed to the electric field conducted electrons trapping/de-trapping in the deep-energy-level traps produced by theoxygen grabbingprocess.The stochasticity of the electrons trapping/detrapping governs the random distribution of the set/reset switching voltages of the device,making a single memristor act as a random bit in which the resistance of the device represents information and the applied voltage pulse serves as the triggering signal.The physical implementation of such a random process provides a method of generating the random bits based on memristors in hardware security applications.     

基于新息自适应卡尔曼滤波算法的多类型结构响应重构

为改善传统卡尔曼滤波KF(Kalman filter)算法在过程噪声方差和测量噪声方差未知的情况下响应重构精度降低甚至发散的问题，提出了一种基于新息自适应卡尔曼滤波IAKF(innovation-based adaptive Kalman filter)算法的多类型响应重构方法。首先根据新息统计特性对卡尔曼滤波增益和状态估计误差协方差矩阵进行实时自适应调整；然后利用有限测点的加速度传感器的测量数据，结合模态法对结构各个位置的加速度、速度、位移以及应变进行响应重构；最后对起重机桁架和简支梁分别进行数值模拟和试验分析。结果表明，该方法能够有效地调整过程噪声方差并估计测量噪声方差，未测点的重构响应时程曲线与计算响应或测量响应时程曲线吻合良好。