Influence of the channel electric field distribution on the polarization Coulomb field scattering in In0.18Al0.82N/AIN/GaN heterostructure field-effect transistors

By making use of the quasi-two-dimensional （quasi-2D） model, the current-voltage （l-V） characteristics of In0AsA10.82N/A1N/GaN heterostructure field-effect transistors （HFETs） with different gate lengths are simulated based on the measured capacitance-voltage （C-V） characteristics and I-V characteristics. By analyzing the variation of the electron mobility for the two-dimensional electron gas （2DEG） with electric field, it is found that the different polarization charge distributions generated by the different channel electric field distributions can result in different polarization Coulomb field scatterings. The difference between the electron mobilities primarily caused by the polarization Coulomb field scatterings can reach up to 1522.9 cm2/V.s for the prepared In0.38AI0.82N/A1N/GaN HFETs. In addition, when the 2DEG sheet density is modulated by the drain-source bias, the electron mobility presents a peak with the variation of the 2DEG sheet density, the gate length is smaller, and the 2DEG sheet density corresponding to the peak point is higher.     

漂移管中相对论电子束引导的匹配条件

本文介绍了对连续型相对论电子束的两种引导及箍缩方法:磁场引导和离子通道的静电引导。在线性引导力的假定下,求得了单磁场引导、单静电引导以及同时使用磁场和电场的混合引导的这三种情况下的匹配条件的解析结果。解析公式表明。在混合引导情况下,为了使电子束匹配,当电子束的中和因子线性增加时,相应的引导磁场不是线性地减小。而是抛物线形地减小。本文还使用了模拟束片内电子横向运动的LGERKB编码,通过对N_0个束内电子的模拟计算,求得了电子束包络。电子束的均方根发射度、典型电子轨道、失配和匹配情况下的束内电子相空间分布(相图)及其演变过程等大量资料。线性模拟结果与解析分析结果完全一致。     

火花通道长度对激光触发开关特性的影响

利用超高速相机,在曝光时间100 ns时,对不同能量下激光在氮气气体开关中形成的火花通道进行拍照,得到了不同焦距下激光波长266 nm时激光火花通道长度与激光能量的关系。开展了激光触发气体火花开关的实验研究,激光触发开关延时、抖动随激光能量的增加而减小。将火花通道长度与激光触发开关的特性进行了分析,气体开关的抖动随着激光火花通道长度的增加而减小,当火花通道沿电极间轴向长度达到开关电极间距40%时,开关的抖动为亚ns量级。     

Control of reaction channels of CsI molecule by ultra-short laser pulse

The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.     

Synergistic effects on iodine release in potassium iodide solution by combination of ultrasound and visible light irradiations

Iodine release in potassium iodide solution has been investigated under the irradiations of ultrasound and visible light respectively and simultaneously. We have observed that the amount of iodine liberated under the combined irradiation of ultrasound and visible light is larger than the sum of that under the respective irradiations of ultrasound and visible light, indicating a synergistic effect of ultrasound and visible light irradiations. Based on the investigation of the reaction kinetics of iodine liberated, we have ascribed the synergistic effect to the perfect stirring of the photochemical reactor induced by the applying simultaneous ultrasound. The ideal stirring can result in the homogenization of the primary light effect in the whole reaction medium, which induces the acceleration of the photochemical reaction. On behavior of our knowledge, there are few reports on the investigations of utilizing the combination of ultrasonic energy and light energy to accelerate the reaction yield and rate as well as the kinetics of the reaction.     

Enhancing teleportation fidelity by means of weak measurements or reversal

The enhancement of teleportation fidelity by weak measurement or quantum measurement reversal is investigated. One qubit of a maximally entangled state undergoes the amplitude damping, and the subsequent application of weak measurement or quantum measurement reversal could improve the teleportation fidelity beyond the classical region. The improvement could not be attributed to the increasing of entanglement, quantum discord, classical correlation or total correlation. We declare that it should be owed to the probabilistic nature of the method.     

基于生命期模型的无线传感器网络信道分配博弈算法

针对无线传感器网络中节点因干扰过大导致重传能耗增加, 进而节点过早失效、网络生命期缩短的问题, 根据网络拓扑信息和路由信息设计节点的负载模型, 从而构建了节点的生命期模型. 然后利用博弈论将路径增益、交叉干扰和节点生命期等性能参数融入到效益函数中, 构建信道分配博弈模型. 理论分析证明该博弈模型存在纳什均衡. 进而运用最佳回应策略, 在所构建的信道分配博弈模型的基础上, 设计了一种优化网络生命期的抗干扰信道分配算法. 该算法使节点在选择信道时避免与网络中交叉干扰较大的节点和生命期较小的节点使用相同信道, 实现干扰小、能耗低且均衡的信道选择. 理论分析与仿真结果证明该算法最终能够快速地收敛到纳什均衡, 且具有较小的信息复杂度, 从而减小算法本身的通信能耗. 同时, 该算法具有良好的抗干扰性和信道均衡性, 能够有效地延长网络生命期.     

不同重力下窄通道内薄材料表面的火焰传播

在常重力下模拟微重力燃烧对载人航天器的火灾安全具有重要意义.窄通道就是这样一种可以有效限制自然对流的模拟设施.但是,不同重力下火焰传播的相似性仍然是有待研究的问题.本文用实验和数值模拟的方法,比较了不同重力下有限空间内热薄材料表面的逆风传播火焰.不同重力下火焰形状和火焰传播速度的比较表明,1cm高的水平窄通道可以有效地限制自然对流,在常重力下用这种通道能够模拟微重力下相同几何尺寸的通道中的火焰传播.因此,在地面上首先利用水平窄通道,模拟相同环境中的微重力火焰传播,然后考虑通道尺寸变化对火焰传播的影响,有可能成为地面模拟其他尺寸的空间中的微重力燃烧的方法.     

Thermal impact on spiking properties in Hodgkin-Huxley neuron with synaptic stimulus

The effect of environmental temperature on neuronal spiking behaviors is investigated by numerically simulating the temperature dependence of spiking threshold of the Hodgkin-Huxley neuron subject to synaptic stimulus. We find that the spiking threshold exhibits a global minimum in a specific temperature range where spike initiation needs weakest synaptic strength, which form the engineering perspective indicates the occurrence of optimal use of synaptic transmission in the nervous system. We further explore the biophysical origin of this phenomenon associated with ion channel gating kinetics and also discuss its possible biological relevance in information processing in neuronal systems.