平行/重合D膜超势，Ooguri-Vafa不变量与类型II弦理论/F理论对偶     

蒋笑添  杨富中 《中国科学院大学学报》2019,36(5):590-597

利用类型Ⅱ弦理论/F理论对偶，第一次在平行和重合相区计算一个具体的双D膜系统的超势，并提取Ooguri-Vafa不变量。平行D膜相与重合D膜相间的相变也对应着D膜世界叶上规范理论规范对称性的提升U（1）×…×U（1）→U（n）。计算显示这两个相区的超势截然不同，并给出不同的Ooguri-Vafa不变量。这意味着相变的发生导致两个相区能谱结构的差异。  相似文献   

Application of colour metallography in the examination of ancient metals     

David A. Scott 《文物保护研究》2014,59(2):113-122

The use of colour in the metallographic examination of ancient metals is useful both for research and teaching purposes. Application of different optical methods of examination include: polarized light, with or without a first-order red compensator, and differential interference contrast microscopy (DIC). The use of DIC can be combined with the other techniques mentioned in the text for the examination of etched or unetched metal surfaces, which are best observed microscopically using a metallograph. Colour techniques are now used routinely in industrial metallography, and are available for a variety of metals and alloys. Colour tint etching can be used to enhance grain structure or different phases present in the metallic artefact which may not be visible in conventional etched samples, or which lack optical contrast. Many more applications of these techniques in the examination of ancient metals will be published in the literature as they become better known and second-hand equipment with DIC lenses enter the market at a price suitable for conservation laboratories to purchase them.  相似文献   

ErCl₃-CaCl₂体系的热力学优化和计算     

孟祥珍  孙益民 《巢湖学院学报》2011,(6):101-103

根据实验测定的相图,运用CALPHAD技术对ErCl3-CaCl2体系进行了热力学优化和计算.计算出的相图属于简单低共熔型,低共熔点为850.92K,46.0%(摩尔分数)ErCl3,同时优化计算了该体系的液相混合焓和相互作用系数.这些热力学参数对于稀土金属及其合金的冶炼有重要意义.  相似文献   

SA/rGO@CuS光热转化复合相变材料制备及性能研究的综合实验设计     

王静静  李泽超  孙建林  梁凯彦  梁贝星  王鹏宇  李旻咛 《实验技术与管理》2021,(2):68-72

结合科研工作热点和学科前沿方向,该文设计了"SA/rGO@CuS光热转化复合相变材料制备及性能研究"综合性实验。将具有光吸收能力的硫化铜(CuS)纳米粒子负载在具有高导热系数的还原氧化石墨烯(rGO)上,制备得到rGO@CuS复合物,以其为载体材料负载相变芯材十八酸(SA),设计制备出具有光捕集、光热转换和定形相变储能于一体的SA/rGO@CuS复合相变材料。通过扫描电镜、透射电镜、拉曼光谱仪、X射线衍射仪、傅里叶变换红外光谱仪、差示扫描量热仪等,对其进行结构表征及性能测试。本实验在培养学生掌握基本实验操作技术的同时,能够提升其逻辑分析能力和对科学研究的热情。  相似文献   

高温相变材料在重力热管外表面凝固的偶合计算     

胡杭英  顾文斌 《科技通报》1995,11(2):74-78

利用高温相变材料储热，同时用重力热管作为能量传输元件这一高效偶合装置在生产和生活中有广阔的应用前景。本文在实验基础上建立一个考虑自然对流影响的相变传热与热管传热相偶合的传热模型，并对该模型进行数值计算，通过与实验结果进行的对比，证实所建立的模型与所采用的计算方法均是合理可行的。  相似文献   

AlN/ZL101原位复合材料的正交实验研究     

田龙  朱艳芳  田青 《安阳工学院学报》2006,(6):8-11

通过正交实验分析,利用气液反应法制备原位AlN/ZL101复合材料并确定了其最佳成分,测试了复合材料的力学性能并对该材料进行了显微金相分析和透射电子显微分析。研究结果表明:AlN/ZL101原位复合材料中原位生成增强体AlN的尺寸为30nm左右,均匀分布于共晶体内部,同基体结合良好;由于细小增强相的作用,热处理后复合材料中的共晶硅以粒状形态均匀分布于基体中。  相似文献   

相变潜热随温度的变化及其对物质的蒸气压方程的影响   总被引：2，自引：0，他引：2  

李永平  李瑞杰 《廊坊师范学院学报》2005,21(4):88-89

当物质发生一级相变时，相变潜热是温度的函数．考虑与凝聚相达到平衡的饱和蒸气，当相变潜热随温度发生变化时，求得物质的蒸气压方程．  相似文献   

TiO2粉末多晶X射线衍射Rietveld全谱拟合定量相分析     

韩海波  陈虹锦  钱雪峰  宰建陶 《实验室研究与探索》2011,30(12):34-37

采用Rietveld全谱拟合的方法对TiO2粉末中锐钛矿和金红石进行定量分析,通过标准样品数据和计算结果进行比较,对该方法的准确性、重复性以及普适性分析,计算结果与标准样品数据符合良好.该方法具有快速准确、成本低、可重复的特点,在高纯度矿物产品工业中将具有广阔的应用前景.  相似文献   

柴油机喷雾特性的电喷控制电路设计     

齐放  张乐超  许沧粟 《实验室研究与探索》2011,30(7):6-10

介绍了一种柴油机电控喷油器喷射开启控制系统。为实现柴油机电控喷油器的开启、持续喷油、关闭功能,应用STC12系列单片机构成电控喷油器的控制系统。开启时为使喷油器开启迅速,应用单周期控制技术的IR1150S芯片,产生高压为112 V的高压电源为喷油器供电。试验结果表明,开发的柴油机电控喷油器控制系统符合X光相衬成像技术研究柴油机喷雾雾化机理的要求,喷油开启迅速、喷油持续稳定、关闭干脆。本系统根据设定可实现电控喷油器的单次及多次连续开启,进一步可以推广应用于柴油机喷油器相关环节教学实验中。  相似文献   

Informing in-season tactical periodisation in team sport: development of a match difficulty index for Super Rugby     

Samuel J. Robertson  David G. Joyce 《Journal of sports sciences》2015,33(1):99-107

In team sports, tactical periodisation refers to the planned manipulation of training loads with the aim of prioritising athlete readiness for matches of greatest importance. Although monitoring of athletes’ physical condition is often used to inform this planning, the direct influence of external factors on match difficulty has not been well quantified. In this study, a ‘match difficulty index’ (MDI) for use in Super Rugby was developed, based on the influence imparted by five external factors on previous match outcomes. Specifically, information relating to match location, days break between matches, time-zone change and opposition ladder position (both current and previous year) were collected for matches played during the 2011–2013 Super Rugby seasons. Logistic regression analyses were used to assess the importance of each of these factors with respect to match outcome (win/loss), with opposition ladder position and match location (home, domestic away or international) exerting the greatest influence on match difficulty. Three separate cross-validated models were constructed, with match outcome classification performance reported as 66.2%, 65.5% and 63.7% respectively. The three MDI models emanating from this study can each be used to inform tactical periodisation program design both prior to and during the regular season.  相似文献