Search

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The seepage characteristics of granite are complicated due to flow exchange between fractures and micropores, which are strongly heterogeneous and anisotropic. The potential geothermal reservoirs of hot dry rocks are often related to granite. The key to geothermal production from hot dry rocks is to generate an efficient fracture network through enhanced geothermal system (EGS) technologies. Although hydraulic fracturing technology is applied in most EGS projects worldwide, it has been indicated that thermal and chemical stimulation methods are also efficient. In this paper, different thermal and chemical treatments are applied to Mesozoic granite samples obtained from geothermal region of Liaodong Peninsula in northeastern China, and their impacts on the seepage characteristics of the granite are carefully analyzed. The thermal and chemical damage mechanisms of granite, in terms of the mineral components, microstructures and physical properties, are also studied. The results show that cooling in cold water results in a much larger permeability increase than that achieved with cooling in air after the granite is heated to a specific temperature. Thermal treatments cause mechanical damage (e.g., compressive strength, elastic modulus, etc.) of granite. However, the differences between the damage factors of various granite samples are large, which are highly dependent on the original mineral composition and microstructures. Thermal cracking induced by either thermal fatigue or thermal shock causes changes in the porosity and permeability of granite. The permeability of the granite changes substantially, i.e., 3–4 orders of magnitude, after soaking in mud acid solutions, while it changes by less than 1 order of magnitude after soaking in alkaline solutions. The dissolution ability of the mud acid solution with the highest concentration (12% HCl + 3% HF) is the strongest among the three types of mud acid solutions tested (S1, S2 and S3). But it mainly acts on improving the proportion of small pores with the size of 0.01–10 μm. It has the least impact on the generation of large pores (10–50 μm), which may be caused by the heterogeneity of mineralogy among different granite samples. Different chemical solutions infiltrate the interior of the granite through various micropores and fissures, enhancing the chemical interaction through the dissolution and precipitation of minerals, the porosity, and the permeability, destroying not only the grains and minerals but also the microstructures of the granite. [ABSTRACT FROM AUTHOR]

Purpose With continuous concerning on the toxic of element Pb, Pb-free solder was gradually used to replace traditional Sn-Pb solder. However, during the transition period from Sn-Pb to Pb-free solder, mixing of Sn-Pb and Pb-free is inevitable occurred in certain products, and in China where Sn-Pb solder was still used extensively in certain areas especially. Correspondingly, understanding reliability of Sn-Pb solder joints was very important, and further studies were needed.Design/methodology/approach Thermal shock test between −55°C and 125 °C was conducted on Sn-37Pb solder bumps in the BGA package to investigate the microstructure evolution and the growth mechanism of interfacial intermetallic compound (IMC) layer. The effects of thermal shock on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed.Findings Pb-rich phase was coarsened and voids were increased at first; Pb-rich phase was refined and voids were decreased secondly with the increase of thermal shock cycles; the shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67MPa at 2,000 cycles; interfacial IMCs of solder bumps was from typical scallop-type into smooth, the composition of IMCs was from Cu6Sn5 into Cu6Sn5 and Cu3Sn after thermal shock with 1,500 and 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure respectively.Originality/value Compared with the board level test method, the impact shear test for the single solder bump is more convenient and economical and is actively pursued by the industries. The shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67 MPa at 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the feeding response of tropical copepods to short-term thermal shock and provide insight into the potential impact of coastal power plants on the trophic dynamics of tropical coastal ecosystems. Feeding experiments were conducted at three different temperatures (29 °C, 33 °C, and 35 °C) using the copepod Acartia erythraea, collected from Sanya Bay, China. The grazing rate of A. erythraea decreased dramatically in the high temperature treatment. Analysis of 18S rDNA clone libraries revealed that the diet of copepods from different treatments was mainly comprised of diatoms, metazoans, and protozoans; A. erythraea exhibited an obvious feeding preference shift with temperature, with a change from a diatom-dominated diet at 29 °C to a metazoan-dominated diet at 35 °C, and the omnivory index shifted from 0.1 to 2.84 correspondingly. Furthermore, A. erythraea showed a positive feeding response to plant food (i.e., phytoplankton and land plants) in the control treatment (29 °C), but a positive response to animal prey (i.e., metazoans and protozoans) at temperatures exceeding 33 °C, as evaluated by the Ivlev's selectivity index. Our results suggest that copepods could regulate their food intake by considering their energy demands when exposed to short-term thermal stress, which might influence the pathway of materials moving up the trophic system. However, further studies are required to elucidate the effects of elevated temperature on feeding of different organisms in order to predict the influence of thermal pollution on the food web of tropical coastal ecosystems. [ABSTRACT FROM AUTHOR]