RECONSTRUCTION OF ONE DIMENSIONAL MULTI-LAYERED MEDIA BY USING A TIME DOMAIN SIGNAL FLOW GRAPH TECHNIQUE

A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal flow graph and its basic principles are introduced,from which the reflection coefficient of the medium in time domain can be shown to be a series ofDirac δ-functions(pulse responses).In terms of the pulse responses,we will reconstruct both thepermittivity and the thickness of each layer will accurately be reconstructed.Numerical examplesverify the applicability of this

Reconstruction of Highly-efficient Smash-ridging Ecological Cultivation Method for Sustainable Yield-increasing of Soil Plough Layers

With consideration of highly-efficient use of natural resources, reducing production cost and construction of high-standard agricultural fields, rice production of good seed＋fertilizer investment is reformed on basis of research of smash-ridging technology, and rice smash-ridging ecological and highly-efficient cultivation was pro- posed, namely, smash-ridging based deeply poughing and rotary tillage technology was used to loosen soils deeply, with the depth from 13-15 cm to 26-28 cm. Fur- thermore, after soils softening, seedling slinging or direct seeding was adopted, which is dominated by natural rainfall and supplemented by artificial irrigation. The test proved that the technology help increasing yield and profits over 20%, with chemical fertilizer reduced by more than 10%, and labor cost reduced by 10%. What＇s more, if the technology applied once, no-tillage or slight tillage is recom- mended in the field, which would maintain original eco-conditions of soils and reach high yield, with energy, water, labor costs reduced in an environment-friendly way.

An efficient source wavefield reconstruction scheme using single boundary layer values for the spectral element method

In the adjoint-state method, the forward-propagated source wavefield and the backward-propagated receiver wavefield must be available simultaneously either for seismic imaging in migration or for gradient calculation in inversion. A feasible way to avoid the excessive storage demand is to reconstruct the source wavefield backward in time by storing the entire history of the wavefield in perfectly matched layers. In this paper, we make full use of the elementwise global property of the Laplace operator of the spectral element method (SEM) and propose an efficient source wavefield reconstruction method at the cost of storing the wavefield history only at single boundary layer nodes. Numerical experiments indicate that the accuracy of the proposed method is identical to that of the conventional method and is independent of the order of the Lagrange polynomials, the element type, and the temporal discretization method. In contrast, the memory-saving ratios of the conventional method versus our method is at least N when using either quadrilateral or hexahedron elements, respectively, where N is the order of the Lagrange polynomials used in the SEM. A higher memorysaving ratio is achieved with triangular elements versus quadrilaterals. The new method is applied to reverse time migration by considering the Marmousi model as a benchmark. Numerical results demonstrate that the method is able to provide the same result as the conventional method but with about 1/25 times lower storage demand. With the proposed wavefield reconstruction method, the storage demand is dramatically reduced;therefore, in-core memory storage is feasible even for large-scale three-dimensional adjoint inversion problems.

RECONSTRUCTION OF LAYER DATA WITH DEFORMABLE B-SPLINES

A new B-spline surface reconstruction method from layer data based on deformable model is presented. An initial deformable surface, which is represented as a closed cylinder, is firstly given. The surface is subject to internal forces describing its implicit smoothness property and external forces attracting it toward the layer data points. And then finite element method is adopted to solve its energy minimization problem, which results a bicubic closed B-spline surface with C^2 continuity. The proposed method can provide a smoothness and accurate surface model directly from the layer data, without the need to fit cross-sectional curves and make them compatible. The feasibility of the proposed method is verified by the experimental results.

Anti-Corrosion and Reconstruction of Surface Crystal Plane for Zn Anodes by an Advanced Metal Passivation Technique

For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.

基于水合物层骨架重构的低温早强胶凝材料

针对于天然气水合物能源试采过程中出砂导致试采作业被迫终止的问题,在水合物第2次试采工作经验和层内加固、防砂理论的基础上,进行了水合物层骨架重构的低温早强胶凝材料体系构建研究。该研究对比了嘉华G级、超细水泥和早强水泥的低温早期强度和长期长度、粒径分布,基于满足层内加固骨架重构孔隙尺寸,进行了低温早强胶凝材料组分设计,以水泥浆流动度、早强性及成本为目标,尽可能提高固结体的早期强度,为后续增渗提供更多强度下降空间。通过研究超细油井水泥与嘉华G级水泥的配比、早强剂优选及加量优化,构建出了低温早强胶凝材料体系,该体系在15℃水浴下24 h抗压强度可达到12.86 MPa,具有良好的流动性、稠化时间和失水可控性,相较于文献的低温早强水泥浆体系具有更好的增渗高强特性。该研究为后续研究水合物层内骨架重构高渗透、高强度的工作液体系奠定了材料基础。

基于锥形追踪和网络分解的NeRF三维重建方法

在计算机视觉领域,神经辐射场(NeRF)是以空间坐标或者时间、相机位姿等其他维度作为输入,通过多层感知机(MLP)网络模拟目标函数,生成颜色、深度等目标标量的过程。NeRF的应用包括对三维场景进行高质量的重建,而其在处理不同分辨率的场景时会产生过度模糊或者伪影的渲染效果,且存在训练耗时较长的问题。为了解决上述问题,提出基于锥形追踪和网络分解的NeRF三维重建方法。使用锥形追踪的方法,为每个像素投射一个圆锥体,并将投射的圆锥体切割成一系列的圆锥台,沿着该圆锥体进行特征化,通过高效渲染抗锯齿的圆锥台来降低模糊或者伪影效果。为了缩短训练时间,使用网络分解的方法,将原始NeRF接收5维数据的神经网络分解为两个网络,有效地缩短训练时间。实验结果表明,在NeRF_Synthetic、LLFF和Multiresolution数据集中,相比于NeRF、F 2-NeRF等方法,所提方法的峰值信噪比(PSNR)提升了14.4%~24.6%,能够重建出更丰富的细节特征,视觉效果更好,且训练时间大幅降低。

深翻耕-起高垄对镉污染酸紫泥田修复效果的研究

通过大田配对试验,研究了常规耕作和深翻耕—起高垄耕作对土壤—作物的降Cd效果。结果表明:与常规耕作相比,深翻耕—起高垄处理的油菜生物量、Cd富集量和植株Cd的移除率分别提高了22%~39%、28%~180%和56%,后茬水稻茎叶、根的Cd含量和富集系数也分别提高了28%~57%、27%~50%,糙米Cd含量显著降低了42%。此外,深翻耕—起高垄处理0~30 cm土壤中的总Cd含量降低了11%~56%,15~30 cm土壤二乙烯三胺五乙酸提取态Cd(DTPA-Cd)含量也显著降低了59%。糙米Cd含量与土壤DTPA-Cd含量、植株Cd富集转运系数呈显著相关。水田旱作季应用深翻耕—起高垄耕作措施,可能通过提高油菜Cd的移除率,降低了土壤总Cd、Cd生物有效性和水稻Cd转运,从而降低糙米Cd含量。

含分布式电源选址定容的配电网重构双层规划

针对大量分布式电源接入配电网带来的诸多不利影响,文中提出一种综合考虑分布式电源选址定容和配电网重构的双层规划模型.上层以DG投资的年综合成本最小,进行分布式电源的选址定容,下层以有功网损最低,进行配电网重构.同时,引入黑寡妇算法对模型进行求解.首先,采用二维混沌映射进行种群初始化,以增加种群的多样性;其次,引入自适应变化的生殖率和兄弟姐妹相食率,以减少后期算法收敛的时间;最后,引入变异算子,增加种群突变的概率,以帮助算法跳出局部最优并寻求全局最优解.通过仿真验证,文中所提出双层规划模型能显著降低网损,提高电压质量;而改进后的黑寡妇算法在收敛速度和精度方面都表现出更优异的性能.

基于超分辨率图像重建的轻量化目标检测算法研究

利用面向边缘的卷积模块、像素注意力机制和重参数化技术使超分辨率重建算法图像分辨率得到提升,使图像特征细节表现更为优越;利用YOLOv4目标检测算法并结合Focus结构、双向特征金字塔网络和轻量级子通道注意力机制,提高中、低分辨率图像目标检测精度。经实验研究,基于超分辨率重建的轻量化目标检测算法对图像目标具有较好的检测效果,有效提升了图像的检测精度,对提升图像中的细小目标检测精度具有一定的参考意义。

雷达在线重构显示软件设计

面对软件化雷达的发展趋势,立足当前可重构数字阵列系统需开放重构、一装多能的作战需求,文中提出一种通用的雷达在线重构显示软件设计方法,能高效完成雷达系统各项功能的在线重构任务。采用分层体系结构模型,设计了从平台层到应用层的软件整体架构,应用面向服务的设计思想,以插件形式实现了各种应用功能在软件框架中的集成。设计了可配置化阵面重构方法,能适配任意阵面结构的自定义配置。提出了一种流程重构显示软件设计方案,实现了流程重定义后信息处理软件在线升级。应用信息可视化、设计美学等人机交互方法,提供了高效自然的人机交互界面。文中的设计方法已在多型雷达正式应用,满足了系统灵活重构的要求,具有很高的实用价值。

Surface cobaltization for boosted kinetics and excellent stability of nickel-rich layered cathodes

The feasibility of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) as a primary cathode material has decreased due to the fragile cobalt(Co)supply chain and its undesirable effects on structural degradation.LiNi_(0.6)Mn_(0.4)O_(2) deserves greater attention because of its high thermal and cyclic stability,coupled with low raw material and production costs.However,this material suffers from low reversible capacity and poor rate performance.Herein,we rationally design a high-performance cathode structure composed of a robust conductive protective layer,gradient Li^(+)ions conductive layer and stable bulk phase of LiNi_(0.6)Mn_(0.4)O_(2) through surface cobaltization,which not only boosts the reaction kinetics of the electrode but also suppresses particle cracking and mitigates surface structural degradation.As a result,a dramatically improved rate capacity(118.7 vs 53.5 mAh g^(-1) at 5 C)and impressive capacity retention after 300 cycles(90.4% in a full cell)at a high cutoff voltage(4.4 V)are obtained.Co-modified Li-Ni_(0.6)Mn_(0.4)O_(2) is promising to challenge commercial position of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) attributed to the accessible capacity,superior rate capacity,excellent cycle performance,good thermal stability and low cost.Our results open a door for optimizing the use of Co and the structural design of high-nickel cathodes.

西沙群岛中新世藻礁白云岩植物格架、储层特征和成礁模式

传统生物礁成因理论质疑钙藻形成坚固生物礁抗浪结构的能力,将钙藻归类于附礁生物群落。文章利用微焦X射线扫描成像技术(X-CT),研究“西科1井”、“西永2井”中新世红藻珊瑚藻科南海奇石藻(新种)格架岩和绿藻仙掌藻节片岩岩芯。通过三维层析成像直观透视图像,发现钙藻生物营造的藻礁抗浪结构,包括典型红藻柱状格架结构、障积结构和绿藻仙掌藻节片结构,证实钙藻植物是主要的造礁造岩生物。通过三维孔隙重构,获得总孔隙体积、面孔率、孔隙度的物性参数,验证了藻礁是南海沉积盆地中新世重要的油气储集层。提出了藻礁成因模式:造礁钙藻适应海面升降逐步演替–取代,经过钙化–埋藏化石化–白云石化,沉积生成藻礁云岩,造成中新世西沙礁纵向序列的增长。

基于CNN与GAN深度学习模型近壁面湍流场超分辨率重构的精细化研究

由城市抗风减灾的目标出发,城市边界层的高保真再现是工程界亟待解决的关键问题.基于高精度的近地风场,有望实现真实环境下城市建筑风致效应的准确预测.传统的基于气象模型的城市风场模拟方法存在预测耗时长、成本昂贵、求解尺度过高等缺陷.为更准确、高效地预测边界层的空间变化,研究利用超精度卷积神经网络(SRCNN)与生成对抗神经网络(SRGAN),在空间上将低精度的近壁面湍流场超精度重构成高精度的风场.利用近壁面湍流直接数值模拟的公共数据库训练模型并评价模型的重构性能.为寻求合适的超精度模型生成方式,研究围绕训练样本量及网络深度,开展详细的敏感性分析,确定合适的训练网络及其较优的训练参数设置.同时,基于经不同下采样因子处理的低精度流场输入,分析模型在近壁面湍流重构中的适用范围.研究发现,对比于SRCNN模型,SRGAN模型对近壁面湍流内小尺度结构的重现效果更佳.当基于4层卷积残差块、300样本量开展训练时,所生成的SRGAN模型可在较低的训练代价下实现较优的重构效果.当进行10倍超精度重构时,SRGAN模型可保证较理想的预测精度.研究成果为边界层风场的准确重构提供技术支撑,为城区建筑物风致效应的高效预测提供精确的入流条件.

基于Swin Transformer的MRI超分辨率重建

在医学图像分割、配准、影像组学以及计算机辅助诊断过程中,高分辨率的医学图像可以显著提高实验精度。但采集的图像切片厚度较大,对后续的图像分析带来了困难。旨在利用超分辨率重建将MRI头部厚层数据变为薄层数据。为提高超分辨率的精度,将图像分成小块,目标输出层为O_Block,输入层为I_Block。O_Block的大小为16×16像素。为了更精确地处理不同方向的组织纹理现象,I_Block要大于O_Block。在实验中,I_Block分别取32×32、48×48、64×64。实验过程中采用Swin Transformer来实现MRI图像超分辨率以获得头部MRI超分辨结果。实验结果表明,通过该实验可以较好地输入厚层图像来预测薄层图像。

基于DEM和3D重构技术的超薄抗滑封层混凝土细观压实仿真

为了研究超薄抗滑封层混凝土的压实机理与碎石分布,通过CT扫描和3D重构技术对真实的碎石颗粒进行轮廓扫描和三维重建。在此基础上利用EDEM离散元软件建立凸多面体颗粒和压实模型,从颗粒接触动力学角度分析压实过程中颗粒排布、接触力以及配位数的变化。结果表明:由三维重构模型得到的碎石洒布空隙率与实际一致。压实前、后颗粒接触拓扑图的颜色、粗细程度的演化反映出颗粒碰撞的程度。同时在压实荷载作用下,颗粒的平均接触力和配位数逐渐增加并趋于稳定。因此碎石颗粒能够形成稳固的嵌挤结构,从而保障路面的抗滑性能和抗剥落性能。

再生砖混材料力学和耐久特性及其在机场道面垫层的应用

利用回收砖混材料设计了骨架密实型再生砖混混合料(RBCM);结合多种试验综合表征了RBCM在抗压、抗拉、贯入受力状态下的力学特征;考虑实际工况设计了试件循环和粒料循环两类耐久环境,并通过无侧限抗压强度试验量化了RBCM的耐久性能演变;依据现场试验段验证RBCM垫层的工程应用性能。结果表明,RBCM垫层的渗透性较差,宜在其上部设置透水垫层;水泥用量增加对RBCM抗压能力和破坏形态改善明显,其抗压和贯入强度较高,抗拉能力较差;少量水泥掺入使RBCM经过30次循环后的耐久系数仍大于50%;即使不掺水泥,再生砖混垫层的密实度和力学性能仍满足现行垫层设计指标的要求。

Nano-Morphology of a Polymer Electrolyte Fuel Cell Catalyst Layer Imaging, Reconstruction and Analysis

The oxygen reduction reaction （ORR） in the cathode catalyst layer （CCL） of polymer electrolyte fuel cells （PEFC） is one of the major causes of performance loss during operation. In addition, the CCL is the most expensive component due to the use of a Pt catalyst. Apart from the ORR itself, the species transport to and from the reactive sites determines the performance of the PEFC. The effective transport properties of the species in the CCL depend on its nanostructure. Therefore a three-dimensional reconstruction of the CCL is required. A series of two-dimensional images was obtained from focused ion beam- scanning electron microscope （FIB-SEM） imaging and a segmentation method for the two-dimensional images has been developed. The pore size distribution （PSD） was calculated for the three-dimensional geometry. The influence of the alignment and the anisotropic pixel size on the PSD has been investigated. Pores were found in the range between 5 nm and 205 nm. Evaluation of the Knudsen number showed that gas transport in the CCL is governed by the transition flow regime. The liquid water transport can be described within continuum hydrodynamics by including suitable slip flow boundary conditions.

Edge reconstruction of layer-dependentβ-In2Se3/MoS2 vertical heterostructures for accelerated hydrogen evolution

The layer-dependent properties are still unclarified in two-dimensional(2D)vertical heterostructures.In this study,we layer-bylayer deposited semimetalβ-In2Se3 on monolayer MoS2 to form verticalβ-In2Se3/MoS2 heterostructures by chemical vapor deposition.The defect-mediated nucleation mechanism inducesβ-In2Se3 nanosheets to grow on monolayer MoS2,and the layer number of stackedβ-In2Se3 can be precisely regulated from 1 layer(L)to 13 L by prolonging the growth time.Theβ-In2Se3/MoS2 heterostructures reveal tunable type-Ⅱband alignment arrangement by altering the layer number ofβ-In2Se3,which optimizes the internal electron transfer.Meanwhile,the edge atomic structure ofβ-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch(~29%),and the presence ofβ-In2Se3 also further increases the electrical conductivity ofβ-In2Se3/MoS2 heterostructures.Attributed to abundant layer-dependent edge active sites,edge reconstruction,improved hydrophilicity,and high electrical conductivity ofβ-In2Se3/MoS2 heterostructures,the edge ofβ-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance.Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-Lβ-In2Se3.Hence,the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance.

急性阑尾炎相关评分系统联合螺旋CT薄层重建检查对急性阑尾炎的诊断价值

目的探讨急性阑尾炎相关评分系统联合螺旋CT薄层重建检查对急性阑尾炎的诊断价值。方法选取2020年7月至2021年12月上海交通大学医学院苏州九龙医院收治的72例初步诊断为急性阑尾炎的患者作为研究对象,所有患者均采用手术治疗,并以病理结果作为金标准,术前进行螺旋CT薄层重建检查及阑尾炎炎症反应(appendicitis inflammatory response,AIR)评分和Alvarado评分对患者进行评估,分析AIR评分联合螺旋CT薄层重建及Alvarado评分联合螺旋CT薄层重建对急性阑尾炎患者的诊断价值。结果经手术病理检查,72例患者中68例确诊为急性阑尾炎;AIR评分联合螺旋CT薄层重建诊断阳性66例,阴性6例;Alvarado评分联合螺旋CT薄层重建诊断阳性60例,阴性12例。两种诊断方式对急性阑尾炎诊断的特异度及阳性预测值比较差异无统计学意义;AIR评分联合螺旋CT薄层重建对急性阑尾炎诊断的灵敏度、阴性预测值及准确度上均高于Alvarado评分联合螺旋CT薄层重建,差异有统计学意义(P<0.05)。结论AIR评分联合螺旋CT薄层重建对急性阑尾炎的诊断价值较高,可进一步提高急性阑尾炎的诊断率,且为无创检查,对急性阑尾炎患者的诊断和预后评估具有重要意义,值得临床推广应用。