Measurement of VIP Edge Conduction Using Vacuum Guarded Hot Plate
Abstract—Vacuum insulation panel (VIP) is a promising thermal insulator for buildings, refrigerator, LNG carrier and so on. In general, it has the thermal conductivity of 2~4 mW/m·K. However, this thermal conductivity is that measured at the center of VIP. The total effective thermal conductivity of VIP is larger than this value due to the edge conduction through the envelope. In this paper, the edge conduction of VIP is examined theoretically, numerically and experimentally. To confirm the existence of the edge conduction, numerical analysis is performed for simple two-dimensional VIP model and a theoretical model is proposed to calculate the edge conductivity. Also, the edge conductivity is measured using the vacuum guarded hot plate and the experiment is validated against numerical analysis. The results show that the edge conductivity is dependent on the width of panel and thickness of Al-foil. To reduce the edge conduction, it is recommended that the VIP should be made as big as possible or made of thin Al film envelope.
COMPARING ENVIRONMENTAL IMPACTS OF METAL ADDITIVE MANUFACTURING TO CONVENTIONAL MANUFACTURING
Abstract Metal additive manufacturing (AM) is revered for the design freedom it brings, but is it environmentally better or worse than conventional manufacturing? Since few direct comparisons are published, this study compared AM data from life-cycle assessment literature to conventional manufacturing data from the Granta EduPack database. The comparison included multiple printing technologies for steel, aluminum, and titanium. Results showed that metal AM had far higher CO2 footprints per kg of material processed than casting, extrusion, rolling, forging, and wire drawing, so it is usually a less sustainable choice than these. However, there were circumstances where it was a more sustainable choice, and there was significant overlap between these circumstances and aerospace industry use of metal AM. Notably, lightweight parts reducing embodied material impacts, and reducing use-phase impacts through fuel efficiency. Finally, one key finding was the irrelevance of comparing machining to AM per kg of material processed, since one is subtractive and the other is additive. Recommendations are given for future studies to use more relevant functional units to provide better comparisons.
Acetylation analysis of saccharides. 2. Microanalysis of neutral glycosphingolipids by means of acetylation with radioactive acetic anhydride.
Abstract The quantitative analysis of mixtures of glycosphingolipids by acetylation with radioactive acetic anhydride and separation by thin-layer chromatography is described. The method was primarily developed for screening of glycosphingolipid composition of tissues, cultured cells, and virus preparations. The sensitivity and linearity of the method is demonstrated. Although theoretically a much higher sensitivity is achievable, in practive about 10 −9 g of glycosphingolipid can be detected and tentatively identified. As an example, the acetylation pattern of lipids from a preparation of herpes simplex virus is demonstrated.