An easily-prepared impedance matched Josephson parametric amplifier

An impedance matched parametric amplifier (IMPA) with Josephson junctions is fabricated and characterized. A hybrid structure containing coplanar and strip structures is implemented to realize an impedance taper line and a plate capacitor in an LC nonlinear resonator based on Josephson junctions. The upper plate of the capacitor is isolated with SiN_x without grounding as well as the strips. Such easily-prepared designs greatly reduce the requirements for lithography alignment and precision, which makes the fabrication process more reliable. The experimental results show that in such IMPA a gain higher than 25 dB with a bandwidth of about 100 MHz can be obtained. This broadband amplifier operates close to the quantum limit. By adjusting the working point, a higher bandwidth of about 400 MHz can be obtained with a gain of about 17 dB.     

Traffic flow of connected and automated vehicles at lane drop on two-lane highway: An optimization-based control algorithm versus a heuristic rules-based algorithm

This paper investigates traffic flow of connected and automated vehicles at lane drop on two-lane highway. We evaluate and compare performance of an optimization-based control algorithm (OCA) with that of a heuristic rules-based algorithm (HRA). In the OCA, the average speed of each vehicle is maximized. In the HRA, virtual vehicle and restriction of the command acceleration caused by the virtual vehicle are introduced. It is found that (i) capacity under the HRA (denoted as C_H) is smaller than capacity under the OCA; (ii) the travel delay is always smaller under the OCA, but driving is always much more comfortable under the HRA; (iii) when the inflow rate is smaller than C_H, the HRA outperforms the OCA with respect to the fuel consumption and the monetary cost; (iv) when the inflow rate is larger than C_H, the HRA initially performs better with respect to the fuel consumption and the monetary cost, but the OCA would become better after certain time. The spatiotemporal pattern and speed profile of traffic flow are presented, which explains the reason underlying the different performance. The study is expected to help for better understanding of the two different types of algorithm.     

基于CZE-ICP-MS联用技术的碲化镉量子点形态分析方法建立及应用

通过水相法合成了谷胱甘肽和半胱氨酸修饰的水相碲化镉量子点(L-GSH/L-Cys-capped CdTe QDs)，构建了一种毛细管区带电泳-电感耦合等离子体质谱联用方法(CZE-ICP-MS)，实现了CdTe QDs及其降解产物(Cd²⁺和TeO₃^2-)的分离分析。单次进样可以同时对CdTe QDs,Cd²⁺和TeO₃^2-进行定量分析。利用构建的CZE-ICP-MS方法对合成的L-GSH/L-Cys-capped CdTe QDs进行纯化效果表征，并对商品化CdTe QDs进行质量评价。该方法为CdTe QDs的合成过程控制、纯化效果、降解规律及毒代动力学研究提供了途径。     

电化学扫描隧道显微术:以Cu在Au(111)表面初始阶段电沉积为例

电化学扫描隧道显微术能在电解质溶液中获得随电位变化的电极表面高空间分辨率的结构信息及跟踪某些反应过程，为从高空间分辨率的角度理解界面结构和电极过程提供了一种强有力的手段。本文以电化学扫描隧道显微术研究Cu在Au(111)上电沉积初始阶段过程为例，与读者交流电化学扫描隧道显微术实验方面的经验，涉及实验装置、实验操作、实验步骤和注意事项等。