Multi-layer structure formation of relativistic electron beams in plasmas

A two-dimensional electromagnetic particle-in-cell simulation model is proposed to study the density evolution and collective stopping of electron beams in background plasmas.We show here the formation of the multi-layer structure of the relativistic electron beam in the plasma due to the different betatron frequency from the beam front to the beam tail.Meanwhile,the nonuniformity of the longitudinal wakefield is the essential reason for the multi-layer structure formation in beam phase space.The influences of beam parameters(beam radius and transverse density profile)on the formation of the multi-layer structure and collective stopping in background plasmas are also considered.

Micrometer-sized ferrosilicon composites wrapped with multi-layered carbon nanosheets as industrialized anodes for high energy lithium-ion batteries

Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercialization. Herein, we use industrial ferrosilicon as low-cost Si source and introduce a facile and scalable method to fabricate a micrometer-sized ferrosilicon/C composite anode, in which ferrosilicon microparticles are wrapped with multi-layered carbon nanosheets. The multi-layered carbon nanosheets could effectively buffer the volume variation of Si as well as create an abundant and reliable conductivity framework, ensuring fast transport of electrons. As a result, the micrometer-sized ferrosilicon/C anode achieves a stable cycling with 805.9 m Ah g-1 over 200 cycles at 500 mA g-1 and a good rate capability of455.6 mAh g-1 at 10 A g-1. Therefore, our approach based on ferrosilicon provides a new opportunity in fabricating cost-effective, pollution-free, and large-scale Si electrode materials for high energy lithium-ion batteries.

Defect feature recognition method of glass fibre-reinforced structure based on visual image analysis

Glass fibre-reinforced(GFR)structure is extensively used in radome,spoiler and some other equipment.In engineering practice,due to the influence of wear,aging,impact,chemical corrosion of surface structure and other factors,the internal structure of this kind of structure gradually evolves into a defect state and expands to form defects such as bubbles,scratches,shorts,cracks,cavitation erosion,stains and other defects.These defects have posed a serious threat to the quality and performance of GFR structure.From the propagation process of GFR structure defects,its duration is random and may be very short.Therefore,designing a scientific micro defect intelligent detection system for GFR structure to enhance the maintainability of GFR structure will not only help to reduce emergencies,but also have positive theoretical significance and application value to ensure safe production and operation.Firstly,the defect detection mechanism of GFR structure is discussed,and the defect detection principle and defect area identification method are analyzed.Secondly,the processing process of defect edge signal is discussed,a classifier based on MLP is established,and the algorithm of the classifier is designed.Finally,the effectiveness of this method is proved by real-time monitoring and defect diagnosis of a typical GFR structure.The experimental results show that this method improves the efficiency of defect detection and has high defect feature recognition accuracy,which provides a new idea for the on-line detection of GFR structure defects.

Influencing factors on elastic-plastic deformation of multi-layered surfaces under sliding contact

Stress distribution in the gradient multi-layered surface under a sliding contact was investigated using finite element method(FEM). The main structure parameters of layered surface discussed are total layer thickness,layer number and elastic modulus ratio of layer to the substrate. A model of multi-layered surface contact with rough slider was studied. The effect of the surface structure parameters on the elastic-plastic deformation was analyzed.

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings is proposed. In this model calculated are only the potential modes of a unit cell, which is a high-index ring in the low-index background for this fibre, rather than the whole cladding periodic structure based on Bloch＇s theorem to find the bandgap. Its accuracy is proved by comparing its results with the results obtained by using the accurate full-vector plane-wave method. High speed in computation is its great advantage over the other exact methods, because it only needs to find the roots of one-dimensional analytical expressions. And the results of this model, mode plots, offer an ideal environment to explore the basic properties of photonie bandgap clearly.

Structural Traps in Detachment Folds:a Case Study from the 'Comband Trough-like' Deformation Zone/s,East Sichuan,China

Detachment structures occur widely in the crust, and it is the commonest and most important deformation type developed in the region between orogenic belts and basins. The ＇comb-like＇ and ＇toughlike＇ fold belts in eastern Sichuan are caused by multi-layer detachment. The duplex structure is the most important deformation style in the region, exhibiting different characteristics from typical detachment structures. Different deformation styles, scales, and shortenings resulting from independent deformations of various detachment systems would lead to the phenomenon whereby most of the topographical heights in the region do not correspond to the structural heights in depth. Based on systematic structural analysis and combined with practical oil/gas prospecting, four types of structural traps are described from eastern Sichuan Province, which are： detachment and thrust trap; detachment folding trap; fault-flat blocking trap; and detachment layer trap. Meticulous studies on the deformation and distribution of detachment layers in the eastern Sichuan Province will contribute to oil/gas prospecting and selection of potential regions of marine-origin oil/gas prospecting in South China.

A Comprehensive Review on Multi-Dimensional Heat Conduction of Multi-Layer and Composite Structures:Analytical Solutions

Heat conduction in multi-layer and composite materials is one of the fundamental heat transfer problems in many industrial applications.Due to different materials types,interface conditions,and various geometries of these laminates,the heat conduction mechanism is more complicated than that of one-layer isotropic media.Analytical solutions are the best ways to study and understand such problems in depth.In this study,different existing analytical solutions for heat conduction in multi-layer and composite materials are reviewed and classified in rectangular,cylindrical,spherical,and conical coordinates.Applied boundary conditions,internal heat source,and thermal contact resistance as the most critical parameters in the solution complexity investigated in the literature,are discussed and summarized in different tables.Various types of multi-layer structures such as isotropic,anisotropic,orthotropic,and reinforced laminates are included in this study.It is found that although more than half a century has passed since the beginning of the research on heat transfer in multi-layer composites,new researches that can help with a better understanding in this area are still being offered.The challenges and shortcomings in this area are also discussed to guide future researches.

Anisotropy of multi-layered structure with sliding and bonded interlayer conditions

A better understanding of the mechanical behavior of the multilayered structure under extermal loading is the most important item for the structural design and the risk asssment.The objective of this study are to propose and develop an analytical solution for the mechanical behaviors of multi-layered structure generated by axisy mmetric loading,and to investigate the impact of anisotropic layers and interlayer conditions on the multi-layered structure.To reach these objectives,first,according to the goveming equations,the analytical solution for a single layer was formulated by adopting the spatial Hankel transform.Then the global matrix technique is applied to achieve the analytical solution of multi-layered structure in Hankel domain.The sliding and bonded interlayer conditions were considered in this process.Finally,the numerical inversion of integral transform was used to solve the components of displacement and stress in real domain.Gauss-Lcgendre quadrature is a key scheme in the numerical inversion process.Moreover,following by the verification of the proposed analytical solution,one typical three-layered flexible pavement was applied as the computing carrier of numerical analysis for the multi-layered structure.The results have shown that the anisotropic layers and the interlayer conditions significantly affect the mechanical behaviors of the proposed structure.

Multi-layer hierarchical cellulose nanofibers/carbon nanotubes/vinasse activated carbon composite materials for supercapacitors and electromagnetic interference shielding

Developing porous self-supporting electrodes with excellent conductivity,good mechanical properties,and high electrochemical activity is crucial for constructing electrode materials with lightweight,ultra-thin,flexible,and high capacitance performance.In this work,we prepared a cellulose nanofibers(CNFs)/carbon nanotubes(CNTs)/vinasse activated carbon(VAC)(CCV)composite material with a multi-layer hierarchical conductive structure through simple vacuum filtration and freeze-drying.In this composite material,the self-assembly of CNF provides the main skeleton structure of a multi-layer hierarchical structure.CNT provides a fast path for the rapid transfer of electrons and is beneficial for the loss of electromagnetic waves.VAC provides sufficient double layer performance.The synergistic effect of the above three endows CCV composite materials with excellent energy storage performance and electromagnetic interference(EMI)shielding performance.In addition,we endowed the CCV composite with a certain shape and performance by introducing a vitrimer polymer with a dynamic cross-linked network structure.In summary,thanks to the synergistic effect of various components in the multi-layer hierarchical structure,CCV composite materials exhibit excellent integration performance,especially stable energy storage performance and EMI shielding performance.These significant properties make CCV composite materials have great application prospects in the fields of energy storage and intelligent EMI shielding.

Synergistically biomimetic platform that enables droplets to be self-propelled

Droplet transport still faces numerous challenges,such as a limited transport distance,large volume loss,and liquid contamination.Inspired by the principle of‘synergistic biomimetics’,we propose a design for a platform that enables droplets to be self-propelled.The orchid leaf-like three-dimensional driving structure provides driving forces for the liquid droplets,whereas the lotus leaf-like superhydrophobic surface prevents liquid adhesion,and the bamboo-like nodes enable long-distance transport.During droplet transport,no external energy input is required,no fluid adhesion or residue is induced,and no contamination or mass loss of the fluid is caused.We explore the influence of various types and parameters of wedge structures on droplet transportation,the deceleration of droplet speed at nodal points,and the distribution of internal pressure.The results indicate that the transport platform exhibits insensitivity to pH value and temperature.It allows droplets to be transported with varying curvatures in a spatial environment,making it applicable in tasks like target collection,as well as load,fused,anti-gravity,and long-distance transport.The maximum droplet transport speed reached(58±5)mm·s^(−1),whereas the transport distance extended to(136±4)mm.The developed platform holds significant application prospects in the fields of biomedicine and chemistry,such as high-throughput screening of drugs,genomic bioanalysis,microfluidic chip technology for drug delivery,and analysis of biological samples.

Simulation study of multi-layer titanium nitride nanodisk broadband solar absorber and thermal emitter

Solar energy has always been a kind of energy with large reserves and wide application.It is well utilized through solar absorbers.In our study,the finite difference time domain method(FDTD)is used to simulate the absorber composed of refractory metal materials,and its absorption performance and thermal emission performance are obtained.The ultra-wide band of 200 nm-3000 nm reaches 95.93%absorption efficiency,of which the bandwidth absorption efficiency of2533 nm(200 nm-2733 nm)is greater than 90%.The absorption efficiency in the whole spectrum range(200 nm-2733 nm)is 97.17%on average.The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light.The thermal emission performance of the absorber enables it to also be applied to the thermal emitter.The thermal emission efficiency of 95.37%can be achieved at a high temperature of up to 1500 K.Moreover,the changes of polarization and incident angle do not cause significant changes in absorption.Under the gradual change of polarization angle(0°-90°),the absorption spectrum maintains a high degree of consistency.As the incident angle increases from 0°to 60°,there is still 85%absorption efficiency.The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.

商务印书馆董事关系网络的结构探源与启示 (1913—1937)

从1913年到1937年,商务印书馆历年任职董事编织的关系网络呈现出典型的核心—半边缘—边缘三层次关联体系,子群中董事任职经历异质性较大,网络内部结构洞丰富。网络结构的形成过程犹如水波纹扩张,以内部董事为核心向外一圈圈推散出去,成因是路径依赖下的惯性延伸、社会网络中的同质选择和资源依赖下的董事拣选。由此提出出版企业在董事关系网络的构建过程中要注意有机网络与机械网络结合、同质链接与异质链接结合、效率优化与饱和优化结合三点启示。

Development of impact resistant 3D printed multi-layer carbon fibre reinforced composites by structural design

In this study,a high impact resistant multi-layered composite consisting of continuous carbon fibre/nylon(CCF)and short carbon fibre/nylon(SCF)layers is developed via 3D printing technology.The effect of CCF/SCF layers configuration on the impact resistance is investigated by low-velocity impact test,and the impact failure mechanism of the 3D printed composites is explored by microscopic observations and finite element(FE)simulation analysis.The results show that the 3D printed multi-layered composite with SCF layers distributed in the middle(HFA)exhibits higher impact resistant performance than the specimens with alternating SCF/CCF layers(HFB)and CCF layers distributed in the middle(HFC).The effect of CCF/SCF layers proportion on the impact performance is also studied by FE simulation,and the results show that the specimen with a CCF/SCF proportion of 7.0 exhibits the highest impact strength.

EPICS控制系统软件开发环境

为了有效地管理大型科学装置控制系统的软件系统EPICS(Expefimental Physics and Industrial Control System)的开发过程,保证系统的可靠性及可维护性,本文对EPICS的开发环境进行了分析,并通过对软件管理方法、账号权限管理及开发过程的研究,提出并建立了一个统一、便捷和可靠的EPICS软件开发平台。

网络资源层次组织规律定量研究

本文以互联网FTP目录树为对象,从大众构造的层次式结构中揭示管理网络资源时的组织规律。通过考察44,972个软件资源及其在目录树中的位置,得到如下认识:①对于用户查找、浏览资源来说,资源存放在深度为2或3层较适合。②当要管理的资源数量在200以内时,人们可容忍平均1个目录中包含10个左右的软件资源;当资源数量更大时,人们可容忍平均1个目录中包含15个左右的软件资源。③在使用层次式组织结构时,人们会对结构的深度有一个习惯上限,目录结构平均深度一般不多于6层。④人们考虑组织结构时,会在"分类体系复杂度"和"分类精细度"之间权衡,在资源量增多时,尽量保证扁形结构。本文揭示了采用层次方式组织资源时的一些共性,有助于设计更贴近大众习惯的网络资源组织与导航系统,并对标签聚类等从扁平型信息组织方式中提取类目层次的研究工作提供依据。

虚拟产品设计过程中零部件之间的隶属关系问题

针对虚拟产品设计过程中,零部件之间的隶属关系问题进行了研究,指出了虚拟产品设计过程中产品零部件之间的隶属关系不明确这一问题产生的原因,并研究了用计算机操作系统中,“树形目录结构”管理文件的原理来表示虚拟产品设计过程中零部件之间的隶属关系的方法。

计算机领域术语的自动获取与层次构建

设计一种能够自动获取计算机领域术语的方案,提出基于规则与统计相结合的抽取方法,使用亚马逊网站的计算机类图书作为语料库,通过分词、去停止词预处理以及词频统计的方法提取出计算机类领域术语,并插入到由ODP构建的树中,形成计算机领域术语的层次结构。实验结果表明,与人工标注结果相比,使用该方法自动获取的术语有很高的准确率与召回率。

视频结构化浏览和查询系统:Videowser

虽然目前存在一些基于镜头的视频分析方法能够为用户操纵视频提供一些方便 .但由于在一个长视频中其镜头数太多 ,单元太小 ,而且单个视频镜头往往也无法表达出潜在的视频语义 ,所有这些都说明有必要在一个更高的层次上去组织视频 .本文提出的视频目录层次结构把视频中镜头在其自身时间及内容的约束下形成若干镜群 ,再对镜群中的镜头进行聚类获得若干视觉相似镜头的集束——镜组 ,据此设计和实现的 Videowser可让用户通过视频的目录层次结构进行非线性的浏览及观看 ;用户除了进行非线性的浏览外 。

TreeView控件在工艺数据管理中的应用

本文比较了Ｖｉｓｕａｌ ＦｏｘＰｒｏ ５ ．０ 中Ｏｕｔｌｉｎｅ 控件和ＴｒｅｅＶｉｅｗ 控件的不同特点，说明了使用其中ＴｒｅｅＶｉｅｗ 控件实现树状目录结构管理的一种方法。

几类搜索引擎的原理剖析、比较研究及发展趋势探讨

通过对“搜索引擎”的种类、特点、工作原理及系统结构的剖析 ,阐述“搜索引擎”的强大信息检索功能 ,评价各种搜索引擎的优点及不足之处 ,并对搜索引擎的发展趋势提出一些看法。