Comparison of tunneling currents in graphene nanoribbon tunnel field effect transistors calculated using Dirac-like equation and Schrödinger's equation

The tunneling current in a graphene nanoribbon tunnel field effect transistor (GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrödinger's equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method (TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrödinger's equation.     

基于公理化模糊子集的改进谱聚类算法

谱聚类算法通常是采用高斯核作为相似性度量,并利用所有可用的特征来构建具有欧氏距离的相似度矩阵,数据集复杂度会影响其谱聚类性能,因此该文提出一种基于公理化模糊子集(AFS)的改进谱聚类算法。首先结合AFS算法,利用识别特征来衡量更合适的数据成对相似性,生成更强大的亲合矩阵;再有效地利用Nyström采样算法,计算采样点间以及采样点和剩余点间的相似度矩阵去降低计算的复杂度;最后通过在不同数据集以及图像分割上进行实验,证明了提出算法的有效性。     

ICP-AES法测定钒钛磁铁矿及冶炼渣中痕量钪

系统研究了ICP-AES法的测量条件和基体元素对钪谱线强度的影响.用钇作内标元素,分析线对为Sc361.384mn/Y361.105nm。建立了钒钛磁铁矿及其冶炼渣中痕量钪的直接分析法。     

基于图卷积的异质网络节点分类方法

图表示学习已成为图深度学习领域的一个研究热点. 大多数图神经网络存在过平滑现象,这类方法重点关注图节点特征,对图的结构特征关注度不高. 为了提升对图结构特征的表征能力,提出了一种基于图核同构网络的图分类方法,即KerGIN. 该方法首先通过图同构网络（graph isomorphism network,GIN）对图进行节点特征编码,并使用图核方法对图进行结构编码,进一步利用Nyström方法降低图核矩阵的维度. 其次借助MLP将图核矩阵与图特征矩阵对齐,通过注意力机制将图的特征编码和结构编码进行自适应加权融合,进而得到图的最终特征表示,提升了图结构特征信息的表达能力. 最后在7个公开的图分类数据集上对模型进行了实验评估：与现有图表示模型相比,KerGIN模型能够在图分类准确度上有较大幅度提升,它可以增强GIN对图结构特征信息的表达能力.

     

原发性干燥综合征合并非霍奇金淋巴瘤九例

目的 分析原发性干燥综合征合(pSS)合并非霍奇金淋巴瘤(NHL)患者的临床表现、实验室血清学检查以及淋巴瘤组织学的特征.方法 9例pSS合并NHL的病例,其中女8例,男1例.5例接受过糖皮质激素治疗,其中的4例还接受过至少一种免疫抑制剂治疗.分析pSS合并NHL主要的临床和实验室特点.结果 8例符合美欧合议的干燥综合征分类标准(AECC).患者主要的SS临床表现是无痛性腮腺肿大(7例),其中6例为单侧肿大;血清免疫学主要表现为类风湿因子(7例)阳性,以及高免疫球蛋白血症(7例).NHL主要临床表现包括脾脏肿大(7例)和淋巴结肿大(5例).其主要病理组织亚型是黏膜相关淋巴组织(MALT)B细胞淋巴瘤(4例)和弥漫大B细胞淋巴瘤(2例).MALT患者均无结区受累.8例患者出现结外受累,其中以累及涎腺(4例)和肺脏(4例)为最多.结论 pSS合并NHL患者临床上以单侧腮腺(无痛性)、淋巴结和脾脏肿大,类风湿因子高滴度阳性和高球蛋白血症,MALT为主的NHL病理分型和高发结外受累为主要特征.     

Water relations and leaf growth rate of three Agropyron genotypes under water stress

The effects of water stress on leaf water relations and growth are reported for three perennial tussock grass genotypes under glasshouse conditions. Studies were performed in genotypes El Palmar INTA and Selección Anguil of Agropyron scabrifolium (Döell) Parodi, and El Vizcachero of A. elongatum (Host) Beauv. Agropyron scabrifolium El Palmar INTA is native to a region with warm-temperate and humid climate without a dry season, and an average annual precipitation of 900 mm. Agropyron scabrifolium Selección Anguil comes from a region with a sub-humid, dry to semiarid climate and a mean annual precipitation of 600 mm. Agropyron elongatum is a widespread forage in semiarid Argentina with well-known water stress resistance. A mild water stress treatment was imposed slowly; plants reached a minimum pre-dawn leaf water potential of about -1.83 MPa by day 21 after watering was withheld. In all genotypes, water stress led to a reduction of leaf growth. There was a tendency for a greater epicuticular wax accumulation on water-stressed plants of A. scabrifolium Selección Anguil and A. elongatum than on those of A. scabrifolium El Palmar INTA. This may have contributed to obtain greater turgor pressures and relative water contents in the first two than in the later genotype. In turn, this may have contributed to determine smaller leaf growth rate reductions in A. scabrifolium Selección Anguil and A. elongatum than in A. scabrifolium El Palmar INTA under water stress. This study demonstrated variation in water stress resistance between genotypes in A. scabrifolium, and between A. scabrifolium Selección Anguil and A. elongatum versus A. scabrifolium El Palmar INTA, which was related to their differential responses in water relations.     

钾改性Beta分子筛Brönsted酸性能对十氢萘加氢异构及加氢裂化反应的影响

为了提高十氢萘加氢转化生成桥环异构体的选择性,采用钾（K⁺）后浸渍法对Beta分子筛进行了酸性调节;采用X-射线衍射（XRD）、扫描电子显微镜（SEM）、N₂吸附-脱附（BET）、红外光谱（Py-IR）等分析手段对改性前后的分子筛进行了表征。采用孔饱和浸渍法制备了Pt/Beta-Al₂O₃催化剂,在氢气压力4.0 MPa、温度240~300 ℃、氢/油摩尔比12.62、质量空速10.56 h^-1的条件下,以十氢萘为模型化合物进行了加氢异构化和加氢裂化反应研究。结果表明：随着K₂O负载质量分数从0.105%增加到0.403%,改性前后分子筛的结构及孔道性质未发生明显变化,分子筛BrÖnsted(B)酸酸量从209 μmol/g逐渐下降到123.9 μmol/g;十氢萘加氢转化过程遵循异构化-开环-裂化连串反应机理,随着反应温度升高,异构选择性降低,开环和裂化反应选择性升高,总转化率增大;反应温度低于280 ℃时,桥环异构产物选择性可以达到90%以上。在反应温度300 ℃的条件下,随着K⁺改性分子筛的B酸酸量降低,产物异构选择性增加,开环选择性和裂化反应选择性降低。K+通过抑制裂化反应可以明显提高桥环产物的选择性。     

Convergence Analysis of a Self-Stabilizing Algorithm for Minor Component Analysis

The Möller algorithm is a self-stabilizing minor component analysis algorithm. This research document involves the study of the convergence and dynamic characteristics of the Möller algorithm using the deterministic discrete time (DDT) methodology. Unlike other analysis methodologies, the DDT methodology is capable of serving the distinct time characteristic and having no constraint conditions. Through analyzing the dynamic characteristics of the weight vector, several convergence conditions are drawn, which are beneficial for its application. The performing computer simulations and real applications demonstrate the correctness of the analysis’s conclusions.     

基于线性化核标签融合的脑MR图像分割方法

深层脑结构的形态变化和神经退行性疾病相关, 对脑MR图像中的深层脑结构分割有助于分析各结构的形态变化.多图谱融合方法利用图谱图像中的先验信息, 为脑结构分割提供了一种有效的方法.大部分现有多图谱融合方法仅以灰度值作为特征, 然而深层脑结构灰度分布之间重叠的部分较多, 且边缘不明显.为克服上述问题, 本文提出一种基于线性化核多图谱融合的脑MR图像分割方法.首先, 结合纹理与灰度双重特征, 形成增强特征用于更好地表达脑结构信息.其次, 引入核方法, 通过高维映射捕获原始空间中特征的非线性结构, 增强数据间的判别性和线性相似性.最后, 利用Nyström方法, 对高维核矩阵进行估计, 通过特征值分解计算虚样本, 并在核标签融合过程中利用虚样本替代高维样本, 大大降低了核标签融合的计算复杂度.在三个公开数据集上的实验结果表明, 本文方法在较少的时间消耗内, 提高了分割精度.     

低温下Fe-69.7%Cr合金α'相的穆斯堡尔谱

Fe-69.7%(atom)Cr合金经500℃时效4年后,获得单一α'相结构,并测定了它在低温下合金的穆斯堡尔谱。结果表明:在室温300K穆斯堡尔谱为一单线洛仑兹线型,降低温度其半宽度也随着展宽,在77K时超精细场达3072.20kA/m;超精细场数值随温度降低而增大,其变化规律与顺磁体模型理论值变化曲线相似,说明α'相在77K以上为一顺磁质,从1200℃至室温通过变温热循环加速了Cr句晶界扩散以及顺磁α'相在Fe-24.6%Cr-5.0%Al合金中析出,并导致合金脆化。