几种高性能纤维束的冲击动力学性能实验研究

利用直拉式Hopkinson装置研究了碳纤维、无碱E玻璃纤维、Kevlar 4 9/96 4 /96 4c、Twaron2 0 0 0、DyneemaSk6 6等纤维的动态拉伸性能。与准静态加载条件下相比 ,纤维束的拉伸强度基本与应变速率无关(玻璃纤维除外 ) ,而纤维束的弹性模量和失效应变随应变率的升高而明显变大。从高分子物理以及两种无机纤维的内部微观结构特征对纤维的力学性能与加载速率的关系进行了初步的物理阐释。讨论了实验数据的发散原因。     

低栅极电压控制下带有phenyltrimethoxysilane单分子自组装层的有机薄膜晶体管场效应特性研究

制作了底栅极顶接触有机薄膜晶体管器件,60 nm的pentacene被用作有源层,120 nm热生长的SiO₂作为栅极绝缘层.通过采用不同自组装修饰材料对器件的有源层与栅极绝缘层之间的界面进行修饰,如octadecyltrichlorosilane （OTS）,phenyltrimethoxysilane （PhTMS）,来比较界面修饰层对器件性能的影响.同时对带有PhTMS修饰层的OTFTs器件低栅极电压调制下的场效应行为及其载流子的传输机理进行研究.结果得到,当|V 关键词： 有机薄膜晶体管 自组装单分子层 场效应迁移率 低栅极调制电压     

基于Phong模式的分裂Monte Carlo模拟红外室内信道脉冲响应函数

介绍了基于Phong模式的Monte Carlo方法.该方法能够对红外室内通信的重要性能参数—— 信道脉冲响应函数进行快速有效的计算，可应用于包括漫反射、镜面反射以及粗糙度介于这 两种反射之间的表面反射情形的信道中.相对于经典的有限元法，在高次反射时具有更为明 显的优势，不但计算速度快，而且计算结果也更接近真实信道环境.该方法的使用，能够为 设计高性能红外系统提供更为可靠的参数. 关键词： 红外室内通信 脉冲响应函数 分裂Monte Carlo Phong 模式     

多目标跟踪中目标数量准确识别算法

由于场景中存在目标遮挡与重叠的影响,以及检测时产生的分割错误,同一个目标往往被识别为若干运动区域,或者多个目标被识别为同一个运动区域,从而导致目标数量识别错误。为了解决这一问题,提出了一种结合融合与分离操作的理论来分析视频的方法,将多目标跟踪的问题转化成为一个找寻后验极值的问题。采用图论的方法表示观测结果,利用图像序列中目标运动轨迹和外观相似度的信息,将多目标跟踪的问题归结为找寻图中多个最优路径的问题。该方法采用了滑动窗口框架以便统计固定数目帧的信息。实验结果表明该方法能够应对实际中发生的上述现象,达到了准确识别多目标数量的目的。     

核实验数据获取系统中的触发信号预处理

简要介绍了在核物理实验数据获取系统中,用FPGA芯片和VHDL语言实现对事件触发信号的预处理。阐述了在核物理实验数据获取系统中对事件触发信号的一般要求; 结合60Co伽马谱测量实验,介绍了基于一套自主研发的数据获取系统中触发信号的预处理,并给出了用VHDL语言实现该触发信号预处理的思想、仿真时序图和实验结果。该方法通过实验验证,证明切实可行,灵活性强。     

Multi-qubit controlled-NOT gates and Greenberger–Horne–Zeilinger state generation using one qubit simultaneously controlling n qubits

Based on superconducting flux qubits coupled to a superconducting resonator. We propose a scheme for implementing multi-qubit controlled-NOT (C-NOT) gates and Greenberger–Horne–Zeilinger (GHZ) state with one flux qubit simultaneously controlling on n qubits. It is shown that the resonator mode is initially in the vacuum state, a high fidelity for operation procedure can be obtained. In addition, the gate operation time is independent of the number of the qubits, and can be controlled by adjusting detuning and coupling strengths. We also analyze the experimental feasibility that the conditions of the large detuning can be achieved by adjusting frequencies of the resonator and pulses.     

Comparative assessment of InGaAs sub-channel and InAs composite channel double gate (DG)-HEMT for sub-millimeter wave applications

This work analyses the impact of channel material, channel thickness (T_CH) and gate length (L_g) on the various performance device metrics of Double-gate (DG) High Electron Mobility Transistor (HEMT) by using 2D Sentaurus TCAD simulation. A comparison between In_0.53Ga_0.47As/In_0.7Ga_0.3As/In_0.53Ga_0.47As sub-channel and In_0.7Ga_0.3As/InAs/In_0.7Ga_0.3As composite channel DG-HEMT along with SG-HEMT is made by characterizing the device with structural and geometrical parameters suitable for applications requiring high frequency operations. The DG-In_0.53Ga_0.7As/In_0.7Ga_0.3As/In_0.53Ga_0.7As sub-channel/DG-In_0.7Ga_0.3As/InAs/In_0.7Ga_0.3As composite channel HEMT with channel thickness of 13 nm and barrier thickness (T_B) of 2 nm with L_g = 30 nm are seen offering a positive threshold voltage (V_T) of 0.298/0.21 V, transconductance (g_m) of 3.09/3.3 mS/µm, with cut-off frequency (f_T) and maximum oscillation frequency (f_max) of 776/788 GHz and 905/978 GHz, respectively at V_ds = 0.5 V is obtained. If the channel thickness of the DG-InAs composite channel device is scaled and reduced to 10 nm, the RF performances are further enhanced to 809 GHz (f_T) and 1030 GHz (f_max). Compared to DG-InGaAs sub-channel device, the device with thin DG-InAs composite channel device shows a better performance in terms of drain current (I_ds), analog/RF performance thereby making it preferable for future THz applications.     

Realization of quantum gates by Lyapunov control

We propose a Lyapunov control design to achieve specific (or a family of) unitary time-evolution operators, i.e., quantum gates in the Schrödinger picture by tracking control. Two examples are presented. In the first, we illustrate how to realize the Hadamard gate in a single-qubit system, while in the second, the controlled-NOT (CNOT) gate is implemented in two-qubit systems with the Ising and Heisenberg interactions. Furthermore, we demonstrate that the control can drive the time-evolution operator into the local equivalence class of the CNOT gate and the operator keeps in this class forever with the existence of Ising coupling.     

Complete Analysis of Four-Photon χ-Type Entangled State via Cross-Kerr Nonlinearity

We propose an efficient method to construct an optical four-photon |χ> state analyzer via the cross-Kerr nonlinearity combined with linear optical elements. In this protocol, two four-qubit parity-check gates and two controlled phase gates are employed. We show that all the 16 orthogonal four-qubit |χ> states can be completely discriminated with our apparatus. The scheme is feasible and realizable with current technology. It may have useful potential applications in quantum information processing which based on |χ> state.