多向纤维缠绕小样机的研制

首先对多向纤维缠绕制品的特性进行了分析。然后以实现多向纤维缠绕为基础,从总体结构、芯模零部件设计、传动系统设计以及控制系统设计等几个方面介绍了多向纤维缠绕小样机的研制。这些将为开发功能更完备的大型多向纤维缠绕机械提供很好的实践基础。     

蒙特卡罗在圆度测量精度分析中的应用研究

根据三点法圆度测量的基本原理,重点分析了三测头的测量误差对圆度测量精度的影响.由于三测头测量误差的传递关系非常复杂,因此作者提出了一种采用Monte Carlo随机抽样和随机模拟对此进行分析的方法,直观地确定了由测头测量误差引起的工件轮廓上各点的圆度测量标准差,并通过仿真证明了该方法是有效的.     

Fluxing Agents on Ceramification of Composites of MgO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>/Boron Phenolic Resin

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al₂O₃-SiO₂/boron phenol formaldehyde resin (MAS/BPF) composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS / BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS / BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS / BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.     

Performance evaluation of a new signal processing system design to improve CANDU SDS1 trip response during large break LOCA events

Performance of a recently developed signal processing system for CANDU (Canada Deuterium Uraniu) reactor shutdown system 1 (SDS1) is evaluated in this paper. The evaluation is carried out in MATLAB/Simulink software environment as well as with an existing power measurement and signal processing system. The new signal processing algorithm is obtained based on the synthesis of several first order low pass filters with different delayed time constants. Throughout this paper, a special attention has been paid to compare the new signal processing system with the existing one. The dynamic behavior of the new signal processing system in the practical large loss of coolant accidents (LLOCA) events has also been examined. Simulation results show that during the LLOCA event, the reactor trip time, as well as the peak power, is decreased remarkably. Through the simulation studies, it has convincingly demonstrated that the new signal processing system has significant advantages over the existing system in terms of the improved trip response and accommodation of the spurious trip immunity. This advantage will significantly enhance the safety margin, or will bring economical benefits to nuclear power plants.     

影响电路板线路图形精度的因素研究

随着高频高速产品的快速发展,产品从设计上对图形精度的要求越来越高,但生产良率较低,严重困扰着业界进一步的发展。文章主要从线路板线路图形制作过程中存在不同因素的影响原理出发,针对PCB线路制作的工艺流程,分析了各个流程因素对线路精度制作影响的差异性,通过对这些影响的差异值进行分析和统计,我们确定了对线路精度有要求线路的制作方法和控制要点,有效地提升了制程能力,从而为生产高精度线路图形的高频高速产品提供了生产参考和指导。     

Synthesis and physicochemical characterization of silica aerogels by rapid seed growth method

Thanks to the high optical transparency and ultra-low thermal conductivity, silica aerogels are ideal materials for energy-saving windows. However, their preparation is commonly based on either one-step base-catalyzed method, or two-step acid-base catalyzed method, which is difficult to inhibit the aggregation of clusters while keeping the size of clusters as small as possible and thus degrading silica aerogel's properties. Here, a new idea for synthesizing silica aerogels is presented from the viewpoint of controlling the growth and aggregation of silica clusters. A certain amount of Tetramethoxysilane (TMOS) used as seed precursor is firstly added into the mixture of methanol and distilled water for hydrolysis. A certain time later, the additional TMOS and a defined amount of ammonia are added to the obtained sol for promoting the rapid formation of the gel in several minutes. The silica aerogels prepared by this method have higher optical transparency and lower thermal conductivity than those prepared by the other two methods. This approach may also shed substantial light on controlling the microstructure of other materials prepared by sol-gel process.     

Similarity of binary relations based on rough set theory and topology: an application for topological structures of matroids

In this paper, we propose an integration of rough sets, matroids and topology to exploit the advantages of three theories. First, we consider topologies induced by binary relations and illustrate that binary relations can be researched by means of topology. Next, similarity of binary relations based on rough set theory and topology is introduced and the fact that every binary relation is solely similar to some preorder relation is proved. Finally, as an application of the similarity, topological structures of matroids are given.     

Lipolysis and lipid oxidation caused by Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 isolated from Suan yu,a traditional Chinese low‐salt fermented fish

The aim of this study was to investigate the lipolysis and lipid oxidation of Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 in Suan yu. Suan yu were made inoculated with and without two strains at different stages, and model systems of emulsions were also established. Lipolysis and lipid oxidation were evaluated by determining the changes in free fatty acid (FFA) content and composition, conjugated diene (CD) value and thiobarbituric acid reactive substances (TBARS) value. The total FFA of the sample without cultures increased from 476.61 mg/100 g fat to 1413.89 mg/100 g fat after 5 weeks fermentation, while those of samples with cultures declined to 258.98 and 452.89 mg/100 g fat, respectively. On the other hand, CD and TBARS values of samples with inoculation markedly increased. In the model system, higher FFA, CD and TBARS values for the samples added with CFE were observed. This study showed that Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 made a significant contribution to lipolysis and lipid oxidation during the processing of Suan yu.     

硅钢退火炉氮气冷却的碳套辊分析

阐述了传统硅钢退火炉无冷却碳套辊的缺点,并介绍和分析了通氮气冷却碳套辊的技术特点。     

Cosine interesting pattern discovery

Recent years have witnessed an increasing interest in computing cosine similarity between high-dimensional documents, transactions, and gene sequences, etc. Most previous studies limited their scope to the pairs of items, which cannot be adapted to the multi-itemset cases. Therefore, from a frequent pattern mining perspective, there exists still a critical need for discovering interesting patterns whose cosine similarity values are above some given thresholds. However, the knottiest point of this problem is, the cosine similarity has no anti-monotone property. To meet this challenge, we propose the notions of conditional anti-monotone property and Support-Ascending Set Enumeration Tree (SA-SET). We prove that the cosine similarity has the conditional anti-monotone property and therefore can be used for the interesting pattern mining if the itemset traversal sequence is defined by the SA-SET. We also identify the anti-monotone property of an upper bound of the cosine similarity, which can be used in further pruning the candidate itemsets. An Apriori-like algorithm called CosMiner is then put forward to mine the cosine interesting patterns from large-scale multi-item databases. Experimental results show that CosMiner can efficiently identify interesting patterns using the conditional anti-monotone property of the cosine similarity and the anti-monotone property of its upper bound, even at extremely low levels of support.