Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC–DC voltage

Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard (OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70°C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge (LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge (HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after discharging. The ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.     

诱发IAF夹杂物与原晶粒的尺寸匹配关系

 对于氧化物冶金船板钢而言，细小弥散分布的夹杂物会对其原始晶粒产生钉扎和诱发晶内铁素体的双重作用，且研究发现诱发晶内铁素体的夹杂物尺寸与原始奥氏体晶粒尺寸存在一定的匹配关系。围绕上述问题进行了系统的分析研究和数据统计,结果表明，不同晶粒尺寸下，诱发晶内铁素体的夹杂物尺寸与原奥氏体晶粒度间存在近似线性关系，且随着奥氏体晶粒度的增大，诱发晶内铁素体的夹杂物尺寸则相应减小。     

Recent progress in integration of reforming catalyst on metal-supported SOFC for hydrocarbon and logistic fuels

The metal-supported solid oxide fuel cell (MS-SOFC) is of current research interest in the clean energy field due to its high performance, quick start-up, thermal cycle stability, and lower raw material cost compared to the conventional cermet-based SOFC. To efficiently operate a MS-SOFC using complex hydrocarbon and logistic fuels, it is required to introduce an internal reforming catalyst within the anode metal scaffold. This review article discusses some examples of the performance of MS-SOFCs under hydrocarbon and logistic fuels with and without an additional reforming catalyst. We also discuss the performance improvement of conventional cermet-based SOFCs by adding reforming catalysts via the infiltration method. This information can be directly applied to future MS-SOFC applications. Furthermore, this review article proposes possible novel methods such as direct precursor infiltration, catalyst-anode premixing, and atomic layer deposition methods to introduce the reforming catalyst into a MS-SOFC for improving its initial electrochemical performance and long-term stability under hydrocarbon and logistics fuel.     

板栗壳黄酮结构分析及其对胰脂肪酶活力的抑制作用

在分析板栗壳黄酮结构的基础上，研究其对胰脂肪酶的抑制作用及类型。采用醇提法提取板栗壳中的黄酮，并用AB-8大孔吸附树脂进行纯化，冻干后得到的黄酮含量为（107.50±1.00）mg/g，提取得率为（5.66±0.05）%。利用超高效液相色谱-四极杆/静电场轨道阱质谱联用技术对板栗壳黄酮进行结构分析，鉴定出8 种黄酮类化合物。采用对硝基苯酚法测定胰脂肪酶活力，分别考察板栗壳黄酮对胰脂肪酶的抑制效果及不同反应条件下板栗壳黄酮对胰脂肪酶活性的影响，结果表明，板栗壳黄酮对胰脂肪酶有较好的抑制作用，半抑制浓度（half maximal inhibitory concentration，IC50）为0.074 mg/mL，且使胰脂肪酶最适pH值向碱性偏移。通过Lineweaver-Burk双倒数作图法确定其抑制类型为非竞争性抑制，抑制常数Ki＝53.19 mg/mL。由此可见，板栗壳黄酮是一种效果良好的胰脂肪酶抑制剂。     

Ontology-based approach for the provision of simulation knowledge acquired by Data and Text Mining processes

Numerical simulation techniques such as Finite Element Analyses are essential in today's engineering design practices. However, comprehensive knowledge is required for the setup of reliable simulations to verify strength and further product properties. Due to limited capacities, design-accompanying simulations are performed too rarely by experienced simulation engineers. Therefore, product models are not sufficiently verified or the simulations lead to wrong design decisions, if they are applied by less experienced users. This results in belated redesigns of already detailed product models and to highly cost- and time-intensive iterations in product development.Thus, in order to support less experienced simulation users in setting up reliable Finite Element Analyses, a novel ontology-based approach is presented. The knowledge management tools developed on the basis of this approach allow an automated acquisition and target-oriented provision of necessary simulation knowledge. This knowledge is acquired from existing simulation models and text-based documentations from previous product developments by Text and Data Mining. By offering support to less experienced simulation users, the presented approach may finally lead to a more efficient and extensive application of reliable FEA in product development.     

Selective nonanal molecular recognition with SnO2 nanosheets for lung cancer sensor

SnO₂ nanosheets were developed to detect nonanal gas in the order of ppb which was a marker of lung cancer. The nanosheets showed higher resistance change in nonanal gas than that in carbon monoxide (CO), nitrogen dioxide (NO₂), acetone (CH₃COCH₃), hydrogen (H₂), ethanol (C₂H₆O), ammonia (NH₃), hydrogen sulfide (H₂S), formaldehyde (HCHO), acetaldehyde (CH₃CHO), or butanal (C₄H₈O). Crystal surfaces of the nanosheets would be effective for adsorption of nonanal molecules. Furthermore, it was shown that resistance changed with an increase in carbon number in aldehyde. The nanosheets had molecular selectivity for a series of aldehyde molecules. Molecular recognition of the nanosheets gave us a great advantage to detect nonanal gas which was produced by lung cancer.     

基于Kӧtter方程的盾构掘进面上被切削土体受力研究

为了计算不同土体性质与不同掘进参数下盾构刮刀与土体之间的作用力以及由此带来的切削扭矩,引入了修正后的Kӧtter方程作为补充方程,求解出开挖面上土体在被动切削至破坏时滑动面上的应力分布,建立了被切削土体受力模型,求解出刮刀刃面与土体之间的正压力p、摩擦力Q与侧向土体间抗剪阻力U,进而推导出刀盘切削扭矩T的计算公式。分析得到特定刀盘上刮刀的p,Q,U值随土体c,φ值增大而增大,通过适当提高刮刀刃面粗糙度来增大摩擦可使土体更易被切至破坏;p,Q,U值随刀盘转速ω增大而减小,p,Q随支护荷载p线性增大且p对于被切削土体受力的影响在砂性土中较大,最终给出特定刀盘掘进至部分种类土体中的切削扭矩值作为工程参考。     

一种改进的最小二乘回归子空间分割方法

最小二乘回归(LSR)算法是一种常见的子空间分割方法，由于LSR具有解析解，因此它的聚类性能较高。然而LSR算法是应用谱聚类方法聚类数据，谱聚类方法初始化聚类中心是随机的，会影响后面的聚类效果。针对这一问题，提出一种基于聚类中心局部密度和距离这2个特点的改进的LSR算法（LSR-DC）。在Extended Yale B数据集上进行实验，结果表明，该算法有较高的聚类精度，具有一定的鲁棒性，优于现有LSR等子空间分割方法。     

New environmental-friendly yellow pigments Y_(4-x)A_xMoO_(9+δ)(A =Ta,Tb)

A series of inorganic yellow pigments with general formula Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb), where x = 0,0.05,0.1,0.2, 0.4 for Ta and χ = 0, 0.005, 0.01.0.03, 0.05 for Tb,were synthesized by a conventional ceramic method at 1400 ℃ for 6 h in air. The samples were characterized by XRD,EDS,XPS,SEM,TG-DSC,UV-vis-NIR reflectance spectroscopy and CIE L*a*b* color scales. It is found that the substitution of A(A = Ta, Tb) for Y~(3+) in Y_4 MoO_9 decreases the NIR reflectance of the pigment samples, but the developed pigments Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb) still exhibit impressive NIR solar reflectance. The brighter yellow color of inorganic pigments Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb) is available when x is about 0.1 for Ta and 0.01 for Tb. The results make them a series of potential candidates as ecological yellow pigments because of their high reflectance, lightness, intense coloration and excellent thermal and chemical stability.     

高速率通信网络下时变系统的有限时域H∞控制

针对高速率通信网络和Round-Robin（RR）协议影响下网络化时变系统的有限时域[H∞]控制问题，考虑到系统中存在乘性噪声、随机时滞和量化效应，提出了一种基于观测器的有限时域[H∞]控制器的设计方法。利用李雅普诺夫稳定性理论和线性矩阵不等式（Linear Matrix Inequality，LMI）技术得到有限时域[H∞]控制器存在的充分条件。基于锥补线性化（Cone Complementarity Linearization，CCL）方法通过求解一组递归矩阵不等式得到观测器和控制器参数。所设计的控制器保证闭环网络化时变系统在给定的时域内稳定，且满足预定的[H∞]性能指标。数值仿真验证了所提方法的有效性。