scholarly journals Terahertz-Based Method for Accurate Characterization of Early Water Absorption Properties of Epoxy Resins and Rapid Detection of Water Absorption

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4250
Author(s):  
Hongchuan Dong ◽  
Yunfan Liu ◽  
Yanming Cao ◽  
Juzhen Wu ◽  
Sida Zhang ◽  
...  
Keyword(s):  
Water Absorption ◽  
Epoxy Resin ◽  
Moisture Absorption ◽  
Prediction Method ◽  
Electrical Equipment ◽  
Test Methods ◽  
Test Time ◽  
Terahertz Time Domain Spectroscopy ◽  
Term Operation ◽  
Trace Moisture

Moisture is detrimental to the performance of epoxy resin material for electrical equipment in long-term operation and insulation. Therefore, moisture absorption is one of the critical indicators for insulation of the material. However, some relevant test methods, e.g., the direct weighing method, are time-consuming, and it usually takes months to complete a test. For this, it is necessary to have some modification to save the test time. Firstly, the study analyzes the present prediction method (according to ISO 62:2008). Under the same accuracy, the time required is reduced from 104 days to 71 days. Subsequently, the Langmuir curve-fitting method for water absorption of epoxy resin is analyzed, and the initial values of diffusion coefficient, bonding coefficient, and de-bonding coefficient are determined based on the results of molecular simulation, relevant experiment, and literature review. With the optimized prediction model, it takes only 1.5 days (reduced by 98% as compared with the standard prediction method) to determine the moisture absorbability. Then, the factors influencing the prediction accuracy are discussed. The results have shown that the fluctuation of balance at the initial stage will affect the test precision significantly. Accordingly, this study proposes a quantitative characterization method for initial trace moisture based on the terahertz method, by which the trace moisture in epoxy resin is represented precisely through the established terahertz time-domain spectroscopy system. When this method is used to predict the moisture absorbability, the experimental time may be further shortened by 33% to 1 day. For the whole water absorption cycle curve, the error is less than 5%.

scholarly journals Identifying the Optimal Subsets of Test Items through Adaptive Test for Cost Reduction of ICs

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 680
Author(s):  
Huaguo Liang ◽  
Jinlei Wan ◽  
Tai Song ◽  
Wangchao Hou
Keyword(s):  
Integrated Circuits ◽  
Cost Reduction ◽  
Bayesian Model ◽  
Test Methods ◽  
Test Time ◽  
Test Quality ◽  
Test Cost ◽  
Test Items ◽  
Adaptive Test ◽  
Test Escapes

With the growing complexity of integrated circuits (ICs), more and more test items are required in testing. However, the large number of invalid items (which narrowly pass the test) continues to increase the test time and, consequently, test costs. Aiming to address the problems of long test time and reduced test item efficiency, this paper presents a method which combines a fast correlation-based filter (FCBF) and a weighted naive Bayesian model which can identify the most effective items and make accurate quality predictions. Experimental results demonstrate that the proposed method reduces test time by around 2.59% and leads to fewer test escapes compared with the recently adopted test methods. The study shows that the proposed method can effectively reduce the test cost without jeopardizing test quality excessively.

Evidence for direct water absorption by the shoot of the desiccation-tolerant plant Vellozia flavicans in the savannas of central Brazil

2005 ◽  
Vol 21 (5) ◽  
pp. 585-588 ◽  
Author(s):  
Rafael S. Oliveira ◽  
Todd E. Dawson ◽  
Stephen S. O. Burgess
Keyword(s):  
Water Absorption ◽  
Moisture Absorption ◽  
Terrestrial Plants ◽  
Desert Ecosystems ◽  
Common View ◽  
Central Brazil ◽  
Tolerant Plants ◽  
Aerial Roots ◽  
Alternative Water ◽  
Specialized Structure

Our common view on water uptake by terrestrial plants is that it occurs via absorption by roots from the soil substrate. However, it has long been known that plants exhibit alternative water-absorption strategies, particularly in drought-prone environments. Examples include many tropical epiphytic orchids which use a specialized structure called velamen radicum around their aerial roots for moisture absorption directly from the air (Capesius & Barthlott 1975), specialized trichomes in bromeliads (Andrade 2003, Benzing 1990), uptake by hydathodes into leaves of species inhabiting dry desert ecosystems of Namibia (Martin & von Willert 2000) and foliar absorption by coastal California redwoods during the summer fog season (Burgess & Dawson 2004). One of the most intriguing and yet, least-studied examples of adaptations to severe water limitation is found with desiccation-tolerant plants (also called resurrection plants). During drought periods, the water content of these plants can equilibrate with the low relative humidity of the air to the point that the plants appear dead. However, when water is supplied, these plants fully rehydrate (Alpert 2000, Bewley & Krochko 1982) and become physiologically active. Desiccation-tolerant vascular plants are rare in most ecosystems but diverse in tropical inselbergs (granitic outcrops; Porembski & Barthlott 2000). Relatively little is known about inselberg species particularly from an ecophysiological perspective (see Lüttge 1997 and Klüge & Brulfert 2000 for reviews).

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