Spin and valley dependent line-type resonant peaks in electrically and magnetically modulated silicene quantum structures

A barrier with a tunable spin-valley dependent energy gap in silicene could be used as a spin and valley filter. Meanwhile, special resonant modes in unique quantum structure can act as energy filters. Hence we investigate valley and spin transport properties in the potential silicene quantum structures, i.e., single ferromagnetic barrier, single electromagnetic barrier and double electric barriers. Our quantum transport calculation indicates that quantum devices of high accuracy and efficiency (100% polarization), based on modulated silicene quantum structures, can be designed for valley, spin and energy filtering. These intriguing features are revealed by the spin, valley dependent line-type resonant peaks. In addition, line-type peaks in different structure depend on spin and valley diversely. The filter we proposed is controllable by electric gating.     

电子辐照条件下初始电位对介质材料表面电位衰减特性的影响

为了研究航天器介质材料表面不同电位初始值对表面电位衰减特性的影响。利用航天器带电地面模拟实验设备对聚酰亚胺和聚四氟乙烯介质材料充电到不同电位值,然后关闭电子枪,用电位计测量介质材料表面电位的衰减曲线,并从理论上对cross-over现象进行分析。介质材料初始电位值越大,则表面电位衰减速度越快,且在一定的时间段内电位衰减效率随初始电位值的增大而变大;在相同的真空度条件下,对于初始电位值之和相等的两组衰减曲线,初始电位值之间差值较小的一组衰减曲线更容易出现cross-over现象;出现cross-over现象的时间和电子的迁移率相关,对于相同的两个初始电位,迁移率越大的材料则出现cross-over现象的时间越短,电位衰减会更快。航天器介质材料表面充电电位越大则衰减速度越快,在一定时间的衰减效率越高。     

Z箍缩驱动聚变-裂变混合堆氚燃料循环系统氚盘存量与氚自持初步分析

为研究氚自持条件,建立了Z-FFR氚分析模型,基于理论方程和氚平均滞留时间方法进行计算,得到稳态运行时排灰气处理系统、氚增殖提取系统、同位素分离系统、水去氚化系统的氚质量流分别为52.30,25.40,81.30,3.60 g/day,对应的氚盘存量为52.30,25.40,8.13,1.80 g。同时以氚质量流推导出氚自持判断条件,分析了设计参数能够满足氚自持要求,同时获得了燃烧效率、氚增殖率、提取效率与氚自持的互补关系,三者作为关键参数相互依存,于临界值、设计值、理想值之间分析了氚的自持情况。     

基于PSpice的半导体激光高频调制系统设计

为了实现高频率的调制激光输出,设计了一种驱动系统由信号放大、电流调制、过流保护和具有慢启动功能的直流偏置电路高度集成的半导体激光高频调制系统。此系统采用了结构简单的直接调制方式,运用线性调频的高频信号去控制半导体激光器发射激光的强度,从而实现高频调制。在运用OrCAD/PSpice对高频调制驱动系统进行模拟仿真的基础上,最终研制出的半导体激光高频调制系统实现了频率为40.02 MHz、直流偏置为493.326 mA、正弦波调制电流峰峰值为850 mA的高频调制输出,调制激光平均功率为300 mW。     

Multiple charge ion beam generation with a 2.45 GHz electron cyclotron resonance ion source

<正>Multiple charge ions (MCIs) are necessary for increasing the output energy of particles in accelerators. In general, MCI beams are largely produced by electron beam ion source (EBIS) [1], laser ion source (LIS) [2], or high-frequency (mostly 5 GHz) electron cyclotron resonance (ECR) ion source [3]. Among these, only ECR ion source can operate in the continuous wave (CW) mode, while EBIS and LIS only support pulses. In addition, ECR ion source with lower frequency (mostly 2.45 GHz) are required primarily for generating single charge state ions, because the corresponding ECR field (875 Gs) is not sufficiently strong for MCI generation [4].     

Generic preparation and entanglement detection of equal superposition states

Quantum superposition is a fundamental principle of quantum mechanics, so it is not surprising that equal superposition states (ESS) serve as powerful resources for quantum information processing. In this work, we propose a quantum circuit that creates an arbitrary dimensional ESS. The circuit construction is efficient as the number of required elementary gates scales polynomially with the number of required qubits. For experimental realization of the method, we use techniques of nuclear magnetic resonance (NMR).We have succeeded in preparing a 9-dimensional ESS on a 4-qubit NMR quantum register. The full tomography indicates that the fidelity of our prepared state with respect to the ideal 9-dimensional ESS is over 96%. We also prove the prepared state is pseudo-entangled by directly measuring an entanglement witness operator. Our result can be useful for the implementation of those quantum algorithms that require an ESS as an input state.     

Ionic liquid-based electrolyte with dual-functional LiDFOB additive toward high-performance LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> batteries

Manganese oxide-based cathodes are one of the most promising lithium-ion battery (LIB) cathode materials due to their cost-effectiveness, high discharge voltage plateau (above 4.0 V vs. Li/Li⁺), superior rate capability, and environmental benignity. However, these batteries using conventional LiPF₆-based electrolytes suffer from Mn dissolution and poor cyclic capability at elevated temperature. In this paper, the ionic liquid (IL)-based electrolytes, consisting of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfon)imidate (PYR_1,4-TFSI), propylene carbonate (PC), lithium bis(trifluoromethanesulfon)imide (LiTFSI), and lithium oxalyldifluoroborate (LiDFOB) additive, were explored for improving the high temperature performance of the LiMn₂O₄ batteries. It was demonstrated that LiTFSI-ILs/PC electrolyte associated with LiDFOB addition possessed less Mn dissolution and Al corrosion at the elevated temperature in LiMn₂O₄/Li batteries. Cyclic voltammetry and electrochemical impedance spectroscopy implied that this kind of electrolyte also contributed to the formation of a highly stable solid electrolyte interface (SEI), which was in accordance with the polarization measurement and the Li deposition morphology of the symmetric lithium metal cell, thus beneficial for improving the cycling performance of the LiMn₂O₄ batteries at the elevated temperature. Cyclic voltammetry and electrochemical impedance spectroscopy implied that the cells using this kind of electrolyte exhibited better interfacial stability, which was further verified by the polarization measurement and the Li deposition morphology of the symmetric lithium metal cell, thus beneficial for improving the cycling performance of the LiMn₂O₄ batteries at the elevated temperature. These unique characteristics would endow this kind of electrolyte a very promising candidate for the manganese oxide-based batteries.     

Layered lithium-rich oxide nanoparticles: low-temperature synthesis in mixed molten salt and excellent performance as cathode of lithium-ion battery

Layered lithium-rich oxide, 0.5Li₂MnO₃·0.5LiMn_1/3Ni_1/3Co_1/3O₂, is synthesized in a mixed molten salt of KCl and LiCl under 750 °C. Its morphology and structure are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption and desorption isotherm, and its performances as cathode of lithium-ion battery are investigated by charge–discharge test and electrochemical impedance spectroscopy, with a comparison of the samples synthesized via solid-state reaction. It is found that the resulting product consists of uniform nanoparticles, 50 nm in average, which possesses a well crystallite layered structure although its synthesis temperature is low and thus exhibits excellent cyclic stability and rate capability. The resulting product delivers an initial discharge capacity of 268 mAh g^?1 at 0.1 C and has a capacity retention of 82% after 100 cycles at 1 C, compared to the 243 mAh g^?1 and 73% for the sample synthesized by solid-state reaction under 900 °C.     

Event-based state estimation for a class of complex networks with time-varying delays: A comparison principle approach

The paper is concerned with the state estimation problem for a class of time-delayed complex networks with event-triggering communication protocol. A novel event generator function, which is dependent not only on the measurement output but also on a predefined positive constant, is proposed with hope to reduce the communication burden. A new concept of exponentially ultimate boundedness is provided to quantify the estimation performance. By means of the comparison principle, some sufficient conditions are obtained to guarantee that the estimation error is exponentially ultimately bounded, and then the estimator gains are obtained in terms of the solution of certain matrix inequalities. Furthermore, a rigorous proof is proposed to show that the designed triggering condition is free of the Zeno behavior. Finally, a numerical example is given to illustrate the effectiveness of the proposed event-based estimator.