连续波腔衰荡技术原理推导及实验研究

基于无源腔的Q值定义,根据能量守恒原理,对连续波腔衰荡技术测量原理进行了推导,并基于多光束干涉理论,就入射光关断时间对腔出射光强信号衰荡线形及测量结果的影响进行了数值模拟和分析,分析表明：入射光的关断时间很大程度上决定着腔出射光功率信号的衰减线形,如果要消除入射光关断时间对测量结果的影响,入射光关断必须小于腔衰荡时间的1%。根据理论分析要求建立了一套测量系统,并对腔损耗约为50ppm的低损无源腔进行了实际测量,实验结果的分析显示,该测量系统测量误差约为0．15ppm。     

异构网络中基于Savitzky-Golay滤波的垂直切换算法

为了实现异构网络中的无缝链接和准确地判断网络状态,需加强确定移动台(MS)的位置信息,以及减少不利的衰落效应。本文提出了一种基于Savitzky-Golay滤波(即S-G滤波)的垂直切换算法,该算法能够使MS准确地判断网络的覆盖范围。仿真结果表明,该算法可以减少衰落效应,从而有效地减少了乒乓效应,提高了网络的性能。     

对称型席夫碱类二茂铁衍生物的合成与性能研究

以二茂铁甲醇为原料,经Wittig反应后与2,6-(双胺基)-苯并[1,2-d-4,5-d′]双三唑-4,8(2H,6H)-二酮缩合,合成了一个D-π-A-π-D结构的二茂铁席夫碱类金属有机三阶非线性光学材料。化合物结构经1H NMR,MS表征确认。测定了该化合物的紫外-可见吸收光谱,用简并四波混频(DFWM)检测了其三阶非线性参数,检测波长为800 nm;脉冲宽度为80 fs。该化合物的三阶非线性极化率χ(3)值为3.67×10-13esu(静电单位),分子二阶超极化率γ值为3.49×10-31esu,表明该化合物具有良好的三阶非线性光学性能,优于现有的二茂铁类金属有机材料。探讨了分子结构对三阶非线性光学性能的影响,长共轭链、强电子离域能可提高分子三阶非线性光学性能。     

一种基于GRU神经网络的电力负荷预测

针对电力负荷序列不稳定且传统的神经网络在电力负荷预测中预测精度较低等问题,提出了门控循环单元神经网络(Gated Recurrent Unit Neural Network,GRU)负荷预测的方法.利用python编程语言在Tensorflow框架在搭建门控循环单元神经网络,将影响电力负荷的特征数据输入模型中进行训练....     

Measuring performance degradation of virtual machines based on the Bayesian network with hidden variables

In the virtualized environment, multiple virtual machines (VMs) sharing the same physical host are vulnerable to resource competition, which may cause performance interference among VMs and thus lead to VM performance degradation. This paper focuses on measuring CPU, memory, I/O, and the overall VM performance degradation caused by the performance interference according to the properties in the runtime environment of VMs. To this end, we adopt Bayesian network (BN), as the framework for uncertainty representation and inference, and construct a VM property‐performance BN (VPBN) with hidden variables, which represent the unobserved performance degradation of CPU, memory, and I/O, respectively. Then, we present the method to measure performance degradation of VMs by probabilistic inferences with the VPBN. Experimental results show the accuracy and efficiency of our method.     

一种应用于能量攫取系统的低功耗的工作于亚阈值区域的基准电压源的设计

We propose a bandgap reference, which works in sub-threshold regions to the reduce power consumption in applications such as those in energy harvesting systems that stimulate the development of power management for low power consumption applications.Measurements shows that the supply current of the proposed bandgap reference is only 6.87 μA, including a voltage buffer consuming 3.6 μA of supply current, when the supply voltage is 5 V.The supply voltage can vary from 3 to 11 V and the line regulation of the proposed bandgap reference output voltage is 0.875 mV/V at room temperature.The temperature coefficiency is 88.9 ppm from 10 to 100° C when the supply voltage is 5 V.     

汽车制造业信息安全保障管理实施关键过程

信息化是当今世界中国汽车制造业实现跨越发展的重要机遇。企业在信息化的过程中,信息安全问题也越来越突出,因此进行全面的信息安全保障管理势在必行。企业信息安全保障管理是一个多层面的、多因素的、综合的、动态的系统工程。文中就汽车制造企业如何开展信息安全保障管理给出了一个比较全面的实施过程,希望能为企业在信息安全保障管理体系的建设过程中提供一定的技术支持。     

基于波前像差的图像质量评价方法研究

图像质量评价的研究已成为图像信息工程的基础技术之一。由于图像的最终接受者是人,所以评价图像质量应反映出人类的主观视觉感知。为构造一种符合人眼视觉特性的图像质量评价方法,利用点扩散函数针对人眼建立了含有波前像差信息的图像视觉评价模型,并用此模型分别对添加不同噪声的图像进行图像质量评价。实验结果表明,该方法是可行的、有效的,不同的人眼对同一幅图像的评价存在有差异,人眼波前像差越小观察到的图像越清晰。该方法不仅能够在评价图像质量时准确反映人眼的主观感知,而且能够直观地呈现不同人眼实际看到的图像。     

Reversible Formation of g‐C3N4 3D Hydrogels through Ionic Liquid Activation: Gelation Behavior and Room‐Temperature Gas‐Sensing Properties

Many unique properties arise when the 3D stacking of layered materials is disrupted, originating nanostructures. Stabilization, and further reorganization of these individual layers into complex 3D structures, can be essential to allow these properties to persist in macroscopic systems. It is demonstrated that a simple hydrothermal process, assisted by ionic liquids (ILs), can convert bulk g‐C₃N₄ into a stable hydrogel. The gelation occurs through delamination of the layered structure, driven by particular interactions between the IL and the carbon nitride sheets, forming an amphiphilic foam‐like network. This study employs spectroscopic and computational tools to unravel the gelation mechanism, and provides a rational approach toward the stabilization of 2D materials in hydrogels. The solution‐processable hydrogels can also be used as building blocks of complex devices. Chemiresistive gas sensors employing g‐C₃N₄ 3D hydrogels exhibit superior response at room temperature, enabling effective gas sensing under low power conditions.     

基于能效最优准则的双跳中继网络功率分配算法

针对单天线多跳系统中的资源分配策略进行了研究,重点研究了基于能效最优的功率分配算法。所提算法以系统能效最大化为设计目标,以满足指定的系统服务质量(QoS, quality of service)为约束条件,建立了以源节点和中继节点发射功率为设计变量的数学优化模型。通过大信噪比区间近似等效,将原始的非凸优化问题转化为凸优化问题。再利用拉格朗日对偶函数凸优化算法,并借助于Lambert 函数,最终得到一种功率分配方案的闭合形式解,避免了采用交替迭代方法来求解最优化问题。相比传统以系统频谱效率最大化为目标的算法,所提算法能更好地提升系统整体能效,同时降低了功率分配算法的复杂度。