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关键词： Extended X-ray absorption fine structure (EXAFS)   Nondestructive depth profiling   Copper oxide film  

摘要： Auger electrons are generated in a solid lose energy because of inelastic scattering, and the amount of energy loss depends on the distance traveled. These electrons are emitted from a sample surface with various energies depending on the generation depth. An electron analyzer was used to detect energy-loss Auger electrons from a copper plate with a thickness-defined oxide film (39 mm), and extended X-ray absorption fine structure (EXAFS) spectra according to the depth were successfully obtained. The results demonstrate that performing depthresolved analysis of local atomic structures using Fourier transformation of EXAFS oscillations is now possible (e.g., up to similar to 120 nm for Cu). The maximum analysis depth exceeds the value in total electron yield, a common measurement mode, by a factor of about 2.

关键词： 张量基神经网络   雷诺应力各向异性张量   湍流建模   宽速域   小样本  

摘要： 基于Pope修正的有效黏度假设,张量基神经网络(tensor based neural network,TBNN)构建了从雷诺平均方程湍流模型(RANS)的平均应变率张量和平均旋转率张量到高精度数值解的雷诺应力各向异性张量的映射.将高精度数值解用于TBNN的训练,从而使TBNN根据RANS求解的湍动能、湍流耗散率和速度梯度预测其雷诺应力各向异性张量,并与对应的高精度数值模拟结果以及风洞实验结果对比以评估TBNN的预测能力.本工作将TBNN的预测能力从低速域拓展至高超声速工况,分别对低速槽道流、低速NACA0012翼型以及高超声速平板边界层3种工况进行了小样本的训练并成功预测,并以槽道流训练的TBNN较好地预测了低速平板边界层,验证了模型的泛化能力.对于外推的低速槽道流算例,TBNN预测的结果在y^(+)>5的区域与直接数值模拟(DNS)以及实验的误差均在10%以内,预测结果揭示了TBNN对雷诺应力各向异性张量的良好预测能力;对于翼型的预测效果尽管相较于槽道流略有下降,但近壁关键区域较RANS结果仍有显著提升;对于高超声速平板,TBNN在边界层内展现出了良好的预测能力,在y^(+)>5的区域与DNS的误差同样在10%以内.基于Pope本构关系的TBNN方法在平板的高超声速工况下仍能较准确预测边界层内的雷诺应力各向异性张量,方法在宽速域下的预测能力具有较好的表现,且模型泛化能力亦得到了验证.

关键词： 位移测量   光栅位移传感器   单片机   细分与辨向  

摘要： 针对高速、高精度数据采集的实际需求,开发了基于主、从单片机及PC上位机组成的线性位移测量系统。提出了从单片机完成数据采集、从单片机与主单片机采用并行数据传输、主单片机对采集数据显示及向上位机PC串口发送数据硬件实施方案。软件上把读数头输出的信号(脉冲电信号)采用软件细分、辨向、计数、信号处理等环节,最终转换成实际的线性位移值显示出来,并传至PC上位机进行存储、显示等软件编程思路。采用主、从式硬件结构,目的在于避免数据显示、处理等其它任务对采样速度的影响及采集数据的丢失现象,提高了系统数据采集的实时性。

关键词： 高光谱图像   超分辨率重构   张量环   张量核范数   交替方向乘子法  

摘要： 针对高光谱图像超解析问题,提出了一种联合子空间表示、非局部相似性和张量环因子非凸秩约束的超谱-多谱融合模型。首先,基于高光谱图像的全局谱低秩特性,利用原始低空间分辨率高光谱谱域信息将其降维至子空间表示;随后,针对视觉对像在非局部维度上的强相关性,利用多光谱图像的空间冗余信息将降维后子空间图分成多个相似patch组,并对其施加张量环分解挖掘低秩信息。其中,对分解因子添加基于t-SVD的张量核范数约束,并利用非凸log函数逼近本质秩函数,代替传统凸张量核范数约束,在保持其光谱-空间结构的基础上,避免凸函数过度惩罚较大奇异值所导致的有偏解问题。最后,建立完整的融合模型,并采用交替方向乘子法进行变量优化求解。通过多组实验进行验证,结果表明所提模型提高了视觉质量,与现有最新的融合模型相比,该方法在定量评价的数值结果上也有明显优势。新模型充分考虑了高光谱图像的全局谱低秩性,并结合了非局部相似先验与张量环分解的非凸张量因子秩,能够有效实现高光谱图像的超分辨率重构。

关键词： 机械光栅式测缝计   板式无砟轨道   上拱变形   运营监测  

摘要： 高速铁路轨道的稳定性和平顺性是高速铁路正常运营的关键,因此对运营期高速铁路的轨下结构持续地开展变形监测是十分必要的。当前我国对轨道板变形的检测主要是依靠人工肉眼观察式的现场检查和常规水准测量方式进行监测,效率低下,难以在有限的天窗时间内完成辖区内轨道结构的全覆盖检测。基于此,从理论分析和实验测试两方面探讨机械光栅式测缝计应用于无砟轨道板上拱自动化监测的可行性,结果表明机械光栅式测缝计能够抵抗高温、淋水和振动等不良条件的影响,满足轨道板上拱监测的精度要求。

关键词： 矩阵半张量积   模糊逻辑   模糊关系   分层模糊系统  

摘要： 模糊逻辑是一种在不确定性条件下建模和控制复杂过程的革命性方法,在系统建模与控制领域得到了广泛的应用。基于矩阵半张量积理论可以将模糊逻辑表达式转化为代数表达式,借鉴代数系统的经典控制理论与方法来进一步研究模糊逻辑。首先介绍了以矩阵半张量积理论为框架的模糊逻辑的理论研究进展,如模糊关系矩阵、模糊关系方程、模糊关系不等式与分层模糊控制等,其次介绍了基于矩阵半张量积框架下的模糊控制理论的应用,最后给出了基于矩阵半张量积理论的模糊逻辑研究前景。

关键词： 公路运输  

ISBN: (纸本)9787569287769

摘要： 本书以交通数据模型为出发点，从数据模型中提取不同数据对象进行交通特征层面的技术分析，应用集成学习、复杂网络和深度学习理论解决道路交通动态特征分析的关键问题。

关键词： fused deposition modelling   raster orientation   build orientation   quasi isotropic   mechanical behaviour  

摘要： The development of fused filament fabrication has extended the range of application of additive manufacturing in various areas of research. However, the mechanical strength of the fused filament fabrication-printed parts were considerably lower than that of parts fabricated by other conventional methods, owing to the observed anisotropic behaviour and formation of voids by weak interlayer diffusion. Intense studies on the effect of design and process parameters of the printed parts on the mechanical properties have been done, whereas studies on the effect of build orientations and raster patterns needs special concern. The main aim of this work is to fabricate parts printed using quasi-isotropic laminate arrangement of rasters, achieved by a raster layup of [45/0/-45/90](s), and to compare their mechanical properties with those of the commonly used 0 degrees/90 degrees (cross) and 45 degrees/-45 degrees (crisscross) raster oriented parts. The quasi-isotropic-oriented samples were observed with improved mechanical behaviour in tensile, compressive, flexural and impact tests compared to the commonly employed raster orientations.

关键词： composite Cassavastarch   Mg   Optical properties   Dielectric properties   Plasma frequency   Linear attenuation coefficient   Tensile strength  

摘要： Optical and absorption properties of composite shield cassava-starch/Fe3O4/Mg have been studied for various amounts of Mg (0.05 gr, 0.075 gr, and 0.1 gr) by using Fourier transform infra-red (FTIR) spectroscopy and an IBT 103 Irradiator equipped with a Cs-137 radioactive source (emitting gamma-rays with an energy of 662 keV), respectively. The quantitative analysis of the FTIR spectra has allowed to determine the refractive index (n), extinction coefficient (k), dielectric functions (epsilon), and energy loss function (Im (- 1/epsilon)) by applying the KramersKronig (K-K) relations. The transversal optical (TO) phonon frequency is shifted by 1 cm- 1 to higher wave numbers by increasing the amount of Mg in the composite. This indicates a small effect on the optical properties of the lattice when O atoms are partially replaced by Mg ones in the bonding with Fe (probably forming MgxFeO1x). The plasma frequency of the composite cassava starch/Fe3O4/Mg, for various amounts of Mg, remains constant at 1126 cm-1 indicating the formation of a stable bonding between the MgxFeO1-x filler and the cassava starch matrix. The highest linear attenuation coefficient and tensile strength are 4.633 cm-1 and 73.19 Mpa, respectively, for the highest amount of Mg in the composite (APMG 0.1). These results indicate that the composite cassava starch/Fe3O4/Mg shows a high potential as a new type of apron in several applications with gamma-rays.

关键词： Nitrogen   Nutrient balances   Phosphorus   Placement  

摘要： There is an urgent need to replace mineral phosphorus (P) fertilizers placed near the maize seed at sowing with other management strategies to ensure a more environmentally friendly silage maize production and to avoid depletion of the phosphate rock reserve. The main objective of this study was to test and investigate effects of different tine geometry (operation depth and tine width) and use of the nitrification inhibitor (NI) 3,4-Dimethylpyrazole phosphate (DMPP) on early growth and final yields of maize under field conditions with the purpose of replacing mineral starter P fertilizers with row-injected liquid dairy manure (slurry). A two-year field experiment was carried out on a sandy loam and a loamy sand with moderate soil P status according to the Olsen P soil test. Cattle slurry with a NI was row-injected before sowing using newly developed goosefoot tine tips of three widths (8, 17 or 26 cm) with a roller to control injection depth. For the widest tine (26 cm) slurry was placed at 7 or 10 cm depth directly under the maize seed, and for the other tines slurry was placed at 10 cm depth. One of the placement methods was tested with and without a NI. The placement methods were compared to traditional slurry injection with random lateral positions relative to the maize row (non-placed slurry) and increasing rates of mineral P starter fertilizer with and without NI. The study showed that slurry placement using goosefoot tines of 17 or 26 cm width injected at 10 cm depth combined with a NI resulted in similar final yields (up to 17 Mg DM yield ha- 1) as when using mineral P as a starter fertilizer with non-placed slurry on the sandy loam. On the loamy sand, slurry placement increased early P concentration in maize, but final yield benefitted more from the mineral P fertilizer (+ 1.6 Mg DM yield ha-1 compared to the plots receiving non-placed slurry and no mineral P fertilizer). Addition of a NI to placed slurry increased early stage maize leaf P concentration on