A mathematical analysis: From memristor to fracmemristor

The memristor is also a basic electronic component, just like resistors, capacitors and inductors. It is a nonlinear device with memory characteristics. In 2008, with HP's announcement of the discovery of the TiO₂ memristor, the new memristor system, memory capacitor (memcapacitor) and memory inductor (meminductor) were derived. Fractional-order calculus has the characteristics of non-locality, weak singularity and long term memory which traditional integer-order calculus does not have, and can accurately portray or model real-world problems better than the classic integer-order calculus. In recent years, researchers have extended the modeling method of memristor by fractional calculus, and proposed the fractional-order memristor, but its concept is not unified. This paper reviews the existing memristive elements, including integer-order memristor systems and fractional-order memristor systems. We analyze their similarities and differences, give the derivation process, circuit schematic diagrams, and an outlook on the development direction of fractional-order memristive elements.     

A simple analytical model of laser direct-drive thin shell target implosion

A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems, and it has the advantages of high neutron yield, ultrashort fusion time, micro fusion zone, isotropic and monoenergetic neutron. Some analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser, whereas they are imperfect for a 0.35 μm laser implosion experiment. When using the 0.35 μm laser, the shell is ablated and accelerated to high implosion velocity governed by Newton's law, ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target. The new analytical model scales bang time, ion temperature and neutron yield for large variations in laser power, target radius, shell thickness, and fuel pressure. The predicted results of the analytical model are in agreement with experimental data on the Shenguang-III prototype laser facility, 100 kJ laser facility, Omega, and NIF, it demonstrates that the analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.     

小收缩比内爆实验初步研究

在神光III原型装置上,利用8路激光间接驱动充高气压DT靶丸,开展小收缩比内爆实验.实验中测量得到中子产额、离子温度、聚变反应速率峰值时刻(bangtime)等关键物理量,以及它们随烧蚀层厚度变化的规律.从定性和定量两个方面对实验结果进行了分析讨论,推测流体力学不稳定性和内爆不对称性是导致实验结果与一维辐射流体计算结果不一致的原因.     

Identification of Pipeline Inner Wall Geometry Based on the POD⁃RBF Method北大核心CSCD

Based on the proper orthogonal decomposition⁃radial basis function (POD⁃RBF), a geometric identification method for pipeline inner wall was proposed to solve the internal corrosion detection problem of natural gas and oil pipelines. In view of the static magnetic field, the simplified finite element model for the pipelines was established, and the variable⁃geometry sample library was constructed, to realize the response prediction of arbitrary geometry by the POD⁃RBF. The proposed method achieves reduced⁃order analysis and avoids repeated solution of the stiffness matrix due to the geometrical change during the identification process. Hence, it can significantly improve the computation efficiency. Finally, the grey wolf optimization (GWO) algorithm was used to optimize the objective function and avoid the calculation of the sensitivity in the process of geometry change. The numerical examples show that, the proposed method has high efficiency and accuracy in the geometric identification of the pipeline inner wall, with good stability even under introduced noises. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

基于神光Ⅲ原型装置的新型针孔点背光实验

在神光Ⅲ原型装置上发展和改进了新型针孔点背光技术. 通过1600 J/1 ns/351 nm激光与3 μm钛背光靶相互作用产生4.75 keV的点光源, 利用该点光源成像获得了高质量的钨丝以及靶丸图像, 并通过多种诊断设备获取了较为完整的背光源参数. 实验结果表明, 新型的针孔点背光具备高亮度、 高空间分辨等优点, 可以广泛应用于高能量密度物理研究中. 关键词： 高能量密度物理 惯性约束聚变 背光照相 针孔点背光     

再发射技术测量SGⅡ黑腔靶早期对称性

利用再发射技术能够有效测量早期辐射驱动对称性。2011年在神光Ⅱ激光装置上,采用Bi替代靶,通过改变靶丸的支撑方式和优化探测器配置,利用分幅相机获得较高信噪比的Bi球表面再发射图像。利用实验结果获得了入射流不对称性P2分量随时间的变化,对比两种腔长的黑腔,P2分量随时间的变化存在明显差别。两种腔P2分量随时间的变化趋势与采用视角因子模拟的结果基本一致。     

神光Ⅱ激光装置X射线高分辨单色成像技术

介绍了基于球面弯晶的X射线高分辨单色背光成像技术。通过对球面弯晶背光成像系统的分析,获得成像关键性能参数随成像系统设计参数变化的关系,设计了应用于神光Ⅱ激光装置的单色背光成像系统。利用石英球面弯晶,采用Mg的类H共振发射线以及利用云母球面弯晶,采用Mo连续谱中3.14 keV能点进行背光实验,获得了内爆靶丸的单色投影图像,空间分辨在较大范围内好于5 m。这种成像技术在现阶段惯性约束聚变(ICF)实验研究中能够发挥许多重要的作用,特别是对内爆靶丸压缩流线的测量和流体力学不稳定性的诊断。     

巧用AE自带Radio Waves特效模拟卫星信号及无线电波

Adobe公司的After Effects是一款卓越的后期特效制作软件,插件众多,可以轻松实现各种复杂的视觉效果。本文仅以AE自带Radio Waves特效插件为例,与大家共同探讨AE在影视后期动画中的一个具体应用的例子。第一部分:素材准备新建文件中,我们可看到八条参考线,围成了显示安全框(又称运动安全框)和文字安全框(又称标题安全框),如图2所示。其中淡蓝色以内部分也就是处在文字安全框以内的部分在转换为电视信号时可以保证被完全显示,而文件中处于深蓝色以外的部分,也就是处于显示安全框以外的部分在电视设备中将不被显示。知道了安全框的功用后,…     

高德红外RS058旋转式斯特林制冷机设计及性能

斯特林制冷机被广泛用于机载、舰载、装甲车等项目的红外武器装备上,是现代国防非常重要的尖端技术产品之一,实现高性能斯特林制冷机的国产化具有重要战略意义.RS058是高德红外研制的微型旋转式斯特林制冷机系列产品之一,适合中面阵、大面阵探测器使用,本文主要论述制冷机的设计方法及实际性能.在现有0.5 W@77 K规格制冷机的基础上,结合了包括热力学、动力学和驱动控制等在内的理论计算和试验验证,RS058实现了更好的制冷性能,卡诺效率达到6.20%,能够满足制冷红外探测器的使用和国产化需要.     

超短波宽带阻抗变换器的设计与实现

基于传输线变压器原理的超短波超宽带阻抗变换器,在短波和超短波电路中具有十分重要的地位。这类器件 具有相对带宽宽、尺寸小、传输效率高的优异性能。本文采用铁氧体磁环设计了一款基于传输线变压器原理的宽带Ruthroff 型1：4 阻抗变换器和一款宽带四路功率分配器。从测量结果可以看出,两款器件在2 MHz 到500 MHz 的大部分频带范围内, 回波损耗均小于-14 dB,传输损耗均小于1 dB。研究成果对于正确理解传输线变压器器件工作原理、合理确定参数诸元、实现 预期频带特性等方面具有一定参考价值。