基于MiLE法模拟结晶器中大方坯温度场、应力场及流场

应用混合Langrangian和Eulerian法(MiLE)实现了结晶器中GCr15钢大方坯温度场、应力场及流场的动态模拟,模拟结果与实际生产铸坯吻合.铸坯坯壳角部的温度高于中部,铸坯表面从上到下的温度总体呈下降趋势,且等温区间与流场变化具有一定的相似性.铸坯坯壳中部厚度约为17.5 mm,角部厚度约为13.2 mm.凝固坯壳内的应力主要是热应力.坯壳出结晶器时,坯壳外表面处于压缩状态,凝固前沿为完全拉伸状态.有效应变从铸坯外表面到凝固前沿逐渐增大.钢液在前进过程中不断扩张,流速不断降低,当流股到达一定深度后,形成左右对称向上的两个回流,和一对由凝固面一侧向下而由中心向上流动的回流区.     

注流方式对大方坯连铸结晶器内钢水流动与温度状态影响

依据改变水口侧孔射流方向来控制结晶器内钢流流动状态的思想,设计了一种大方坯连铸结晶器新型四分切向水口.对不同类型水口(直通式、四分径向以及四分切向水口)浇注条件下大方坯连铸结晶器内钢水流动形态和温度分布状况进行了流体动力学比较研究.结果表明,新型四分切向水口不仅可以使结晶器内钢水形成上、下两个回流,并能够产生较强的水平旋流.该水平旋流能降低钢水的冲击深度,抑制钢液面波动,促进夹杂物上浮,还具有促进钢水过热耗散的效果.与四分径向水口相比,新型四分切向水口能减弱射流对初生坯壳的冲击,均匀横截面坯壳厚度.此外,该旋流状态使热中心上移,自由液面附近钢水的温度可提高2～6℃,改善化渣条件.     

Rapid Manufacturing of Sand Molds by Direct Milling

Direct milling of sand molds is an important development in rapid manufacturing of sand molds. Direct milling is an effective method for manufacturing single or small batches of cast parts. This paper describes experimental investigations to find sand blocks with the appropriate strength, to describe wear patterns of different tools (high-speed steel (HSS), carbide, and polycrystalline diamond (PCD) tools), and to analyze sand mold cutting mechanisms. The results show that the PCD tool outperformes the other tools in terms of tool life. Average flank wear and micro-tipping are the dominant tool failure modes in the sand mold milling process. With a flank wear limit of 0.3 mm, the PCD tool works continuously for about 70 h under the experimental conditions. The experimental results show that the cutting mechanism for direct milling sand molds differs from metal cutting.     

武夷冻茶霉菌菌相分析及优势菌ITSrDNA鉴定

为研究武夷冻茶霉菌的分布情况,采用镜相分析和PCR（polymerase chain reaction）技术对霉菌进行菌相分析及优势菌种鉴定。结果表明,冻茶中主要菌属有曲霉属、毛霉属、根霉属和青霉属,其中青霉属为优势菌属;对随机分离纯化的青霉进行ITSrDNA鉴定,鉴定结果为壳青霉（Penicillium.crustosum Thom）。分析结果可为微生物污染途径分析以及改进冻茶的冷藏工艺条件提供理论依据。     

气动成型机的设计

采用气动系统控制进行设计的钢管端口成型机，能在一次装夹中将胀形和卷边两个动作连续完成，提高了工作效率。     

小方坯结晶器水温水速对传热过程影响

通过建立结晶器内钢液和水的二维对流-传热耦合模型过程,研究了小方坯结晶器冷却水入口温度和流速对铜管温度和结晶器内平均热流的影响.该模型使用Fluent进行求解,模拟了钢液和冷却水的流动和传热,凝固坯壳的生长,以及热量以辐射和导热两种通过保护渣和气隙.通过将坯壳厚度和铜管温度与其他研究的结果进行对比来验证模型准确性.研究结果表明,结晶器冷却水的温度显著影响铜管的冷面温度,水温超过313K会导致铜管冷面最高温度超过水的沸点.水流速升高0.49 m·s-1能够消除水温升高4K带来的不利影响.     

Paracelsin; characterization by NMR spectroscopy and circular dichroism,and hemolytic properties of a peptaibol antibiotic from the cellulolytically active mnoldTrichoderma reesei. Part B

Summary Paracelsin, a hemolytic and membrane active polypeptide antibiotic of the peptaibol class which is excreted by the moldTrichderma reesei, was obtained by a simplified and isolation procedure utilziing hydrophobic adsorber resin. Investigation by¹³C nuclear magnetic resonance spectroscopy and circular dichroism revealed considerable helical portions in solution, and the very recently accomplished sequence determination of paracelsin allows the discussion of the results with regard to the closely related analogues, alamethicin and suzukacillin. A selective cleavage of the peptide was achieved by careful treatment with various acids, and a buffer of pH 8.25 and of high ionic strength made possible the quantitative determination of the C-terminal phenylalaninol released by means of ion-exchange chromatography. The significance of the production of paracelsin and related mycotoxins of the peptaibol class, exhibiting various kinds of biological activity, is discussed with respect to the extensive effort being made towards biotechnological applications of species, strains and cellulolytically highly active mutants of the fungusTrichoderma.Presented in part at the 5th European Symposium on Animal, Plant and Microbial Toxins, Hannover, August 29–September 2, 1983 and a lecture given at Ciby-Geigy/Basel in March 1984.Acknowledgment. We thank I. Ackermann for excellent and skilled technical assistance and gratefully acknowledge the help of R. Ratz for support in CD spectroscopy.     

金属基橡塑模具抗黏附表面制备的研究进展

如何降低橡塑模具与制品间的黏附力、构建具有抗黏附性能的表面是橡塑模具行业的发展重点和主要任务之一。对近年来国内外关于模具抗黏附性能研究的相关情况进行了综合评述,从表面粗糙度、表面功能层和表面微观结构等角度阐述了模具抗黏附表面制备的发展历程。重点讨论了激光/等离子体刻蚀法、阳极氧化法、电化学沉积法、化学/电化学腐蚀法、物理/化学沉积法、模板法、复合法等抗黏附表面制备的方法,同时对当前金属基体上制备抗黏附表面所面临的问题进行了分析,提出了未来该领域的研究方向和发展前景。     

注塑模热流道温度场的数值分析

通过对热流道的离散，运用数值分析的方法，与冷却分析的瞬态结果耦合，并松弛迭代求解热流道在成型过程中的温度场，在此基础上可以更为准确、可靠地设计热流道的温度调节系统．     

馆藏竹木漆器类文物污染霉菌类群的鉴定与分析

以河南博物院馆藏的雕漆器、漆器、木雕、和竹器共36件为实验材料,对其霉变斑点进行取样,将菌悬液通过涂布平板及浇注平板的方法对采集的95个样品进行了霉菌的分离,获得纯菌种后通过观察霉菌形态特征、显微观察菌丝及产孢结构以及18 SrDNA分子生物学鉴定方法,鉴定曲霉属(Aspergillus)、脉孢菌属(Neurospor...