高性能混凝土的强度与渗透性的关系

一般认为，混凝土的强度越高，其渗透性越低，以及耐久性越好。通过掺与不掺矿渣或粉煤灰高性能混凝土的试验结果表明，纯水泥混凝土的强度与渗透性之间有很好的相关性，其相关系数为０．９７６７；矿渣混凝土及粉煤灰混凝土的强度与渗透性之间相关性较差，相关系数分别为０．８０８１和０．８４１９；所有混凝土的强度与渗透性之间，相关性更差，相关系数为０．６５６６。可见，除非用于纯水泥混凝土之间的相对比较，高性能混凝土的强度通常不能反映其渗透性     

Application of Plackett–Burman design to screen the effective process parameters for biodiesel production

Significance of biodiesel is increasing forever because of increase in environmental pollution caused by fossil fuel and increasing of fossil fuel prices. Hence, the main goal of this study is to screen the effective process parameters for biodiesel production from chicken fat. Plackett–Burman (PB) design was used to screen the effective process variables among molar ratio, catalyst concentration (%), ultrasound power (W), mixing intensity (rpm), reaction time (min), temperature (°C), and moisture level (%). The obtained biodiesel quality is compared with American Society for Testing and Materials (ASTM) standard methods. This result confirms the effectiveness of PB design to screen the effective process parameters for biodiesel production.     

Effects of crack position on fatigue life of large seamless storage vessels made of 4130X for hydrogen refueling station

Fatigue property of CrMo steel is significantly degraded by hydrogen embrittlement (HE), which probably influences the fatigue life of hydrogen storage vessels made of CrMo steel. In this study, tests of fatigue crack growth rate (FCGR) for specimens extracted from the cylinder, juncture and shoulder of a seamless storage vessel made of 4130X for hydrogen refueling station were performed in 45 MPa hydrogen gas. Based on the test results, a finite element method (FEM) based on adaptive grid technique was applied to calculate fatigue life of the vessel with an initial crack at different positions. 3D laser scanning technology was used to build the model which can well conform to the actual vessel. Results indicate that the FCGR of 4130X in 45 MPa hydrogen is approximately 10–15 times of the FCGR in air. The FCGR of specimens from the shoulder is approximately 1.2–1.5 times of that from the cylinder and juncture. However, as the influence of stress distribution, the fatigue life of a vessel with a crack in the middle of the cylinder is lower than that of the vessel which exists crack with the same size at the juncture and shoulder.     

未除气与除气淡爽型啤酒中9种有机酸的阈值

采用ASTM679标准方法测定了未除气与除气淡爽型啤酒中乙酸、乳酸、柠檬酸、苹果酸、琥珀酸、富马酸、丙酮酸、酒石酸和草酸的个人和小组阈值。结果发现,在未除气啤酒中,9种有机酸的小组阈值大小顺序为苹果酸、富马酸、乳酸、柠檬酸、丙酮酸、琥珀酸、乙酸、草酸、酒石酸。其中品评员对苹果酸、琥珀酸、富马酸、草酸和柠檬酸的口感差异相对较小,而对酒石酸、乙酸、丙酮酸和乳酸的口感差异较大。在除气啤酒中,9种有机酸的小组阈值大小顺序为丙酮酸、乳酸、乙酸、富马酸、琥珀酸、苹果酸、酒石酸、草酸、柠檬酸。品评员对柠檬酸、苹果酸和乳酸的口感差异相对较小,而对丙酮酸、草酸、酒石酸、富马酸、琥珀酸和乙酸的口感差异较大。此外还发现未除气和除气啤酒中有机酸阈值差异很大,其中差异最大的是三元酸柠檬酸,其次为二元酸,包括苹果酸、草酸、酒石酸、琥珀酸和富马酸,差异最小的是一元酸,包括乳酸、乙酸和丙酮酸。     

Ten-year exterior durability test results compared to various accelerated weathering devices: Joint study between ASTM International and National Coil Coatings Association

ASTM's Task Group D01.53.03.03 Coil Coating Task Group on Accelerated Weathering was formed to answer a simple question: which accelerated test method best correlates with real-time weathering for highly durable coil coatings? A ten-year study was initiated, and coil coated panels were collected from D01.53 coater members for all current coil coatings technologies destined for exterior exposure applications. The real-time panels were weathered in southern Florida and in Phoenix, Arizona. Accelerated weathering was run, including UV-Condensation tests (with both “A” and “B” bulbs), Xenon Arc Weatherometer, Dew Cycle Weatherometer, and Fresnel-type weathering.     

校园网组网方式的技术探讨

交互网络已成为目前最热门的话题,校园网络的建设已在全国各大学中广泛展开,本文系统论了目前校园网建设中的主要技术ＡＴＭ,快速以太以及千兆以太网等组网的基本方案,比较了其相互优劣,文章指出,在目前的技术条件下,多性价比等各方面来考虑,千兆以太网是目前最佳校园网组建方案,未来的校园网的最佳选择将是宽带ＩＰ网。     

JG600-Ⅰ高压加热器管板堆焊焊接工艺试验

文中介绍了为解决JG600-Ⅰ高压加热器管板(20MnMoNb锻件)和管子(美国ASTM规范A556《无缝冷拔碳钢给水加热器钢管》中B2级)异种材料焊接问题,而采用在管板上堆焊一层低碳钢,从而实现接近同种材料焊接的方法.并制定了堆焊工艺,进行了工艺试验.     

ASTM标准在实验室间检测汽油结果再现性的评价

目前石油产品标准方法在测试质控工作中,已广泛进行实验室间的协作,实验室B通过与实验室A检测结果的比对,对采用ASTM标准检测汽油的结果进行再现性分析,评价两个实验室的结果吻合性,同时,对出现实验室结果不吻合的情况进行了原因分析并提出解决措施.     

电接触领域的ASTM标准

介绍了ASTM标准化组织的历史及所制订的ASTM标准的种类和影响力。详细列举了ASTMB02委员会下属的B02.05和B02.11分技术委员会制定的电接触领域相关标准,根据这些标准的具体内容和相关性,按照术语和分类、电接触材料、电接触材料性能要求与测试方法、电接触过程性能与测试方法、贵金属覆盖层质量评价方法、气体环境腐蚀试验对这些标准进行了分类,并简要介绍了这些标准的主要内容和相互关系。文章还就这些标准对电接触材料生产和电接触性能检测的指导意义进行了讨论。