Prediction of the Fracture Location by Tensile Tests of Gray Cast Iron Based on the Dimensional Changes of Graphite Flakes

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high performance-to-cost ratio. On the other hand, weak graphite flakes present in gray cast iron serve as stress concentrators and adversely affect the material strength. Therefore, it is crucial to examine the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, tensile tests on gray cast iron were carried out using a plate specimen and observed by scanning electron microscopy, and the microscopic deformation was observed on the specimen surface. Particularly, the change in the size of graphite flakes during the tensile tests was examined, and the observed trend was discussed. The experimental results reveal that the dimensional changes in the graphite flakes vary in the observed area and that the final fracture occurs in an area where a large dimensional change is observed, suggesting that the fracture location or critical parts of gray cast iron can be predicted from the dimensional changes of the graphite flakes at an early stage of deformation

Finite Element Study of the Effect of Internal Cracks on Surface Profile Change due to Low Loading of Turbine Blade

Turbine blades for thermal power plants are exposed to severe environments, making it necessary to ensure safety against damage, such as crack formation. A previous method detected internal cracks by applying a small load to a target member. Changes in the surface properties of the material were detected before and after the load using a digital holographic microscope and a digital height correlation method. In this study, this technique was applied in combination with finite element analysis using a 2D and 3D model simulating the turbine blades. Analysis clarified that the change in the surface properties under a small load varied according to the presence or absence of a crack, and elucidated the strain distribution that caused the difference in the change. In addition, analyses of the 2D model considering the material anisotropy and thermal barrier coating were conducted. The difference in the change in the surface properties and strain distribution according to the presence or absence of cracks was elucidated. The difference in the change in the top surface height distribution of the materials with and without a crack was directly proportional to the crack length. As the value was large with respect to the vertical resolution of 0.2 nm of the digital holographic microscope, the change could be detected by the microscope

Extraction of Phytochemicals from Grains of Paradise Using Supercritical Carbon Dioxide

Supercritical carbon dioxide (SCCO2) is one of the green methods to extract plant matters substances. In this study, SCCO2 has been applied as a media to extract the grains of paradise seeds substances at temperatures of 40 – 80 oC and pressures of 20 – 40 MPa using a semi–continuous flow–type system. Results of FT–IR spectra analysis showed that the grains of paradise seeds substances were extracted by SCCO2. The SEM images of the grains of paradise seeds residues also showed that the physical changes of the grains of paradise seeds surface occurred after SCCO2 extraction. The main compounds in extracts were gingerols, shogaols, and paradols. However, the GC–MS may only identify paradol compounds due to gingerols, shogaols, and paradols are homologous series of phenolic ketones and paradols was more stable than gingerols and shogaols. The yields of gingerols, shogaols, and paradols were 9.12, 3.90, and 4.42 mg/g sample, respectively and affected by extraction temperatures and/or extraction pressures

NeISF: Neural Incident Stokes Field for Geometry and Material Estimation

Multi-view inverse rendering is the problem of estimating the scene parameters such as shapes, materials, or illuminations from a sequence of images captured under different viewpoints. Many approaches, however, assume single light bounce and thus fail to recover challenging scenarios like inter-reflections. On the other hand, simply extending those methods to consider multi-bounced light requires more assumptions to alleviate the ambiguity. To address this problem, we propose Neural Incident Stokes Fields (NeISF), a multi-view inverse rendering framework that reduces ambiguities using polarization cues. The primary motivation for using polarization cues is that it is the accumulation of multi-bounced light, providing rich information about geometry and material. Based on this knowledge, the proposed incident Stokes field efficiently models the accumulated polarization effect with the aid of an original physically-based differentiable polarimetric renderer. Lastly, experimental results show that our method outperforms the existing works in synthetic and real scenarios

Laninamivir octanoate for post-exposure prophylaxis of influenza in household contacts: a randomized double blind placebo controlled trial

AbstractLaninamivir octanoate, a long-acting neuraminidase inhibitor, is an effective treatment for influenza. However, its effectiveness for the prevention of influenza has not yet been demonstrated. We conducted a double-blind, multicenter, randomized, placebo-controlled trial to determine whether laninamivir octanoate was superior to a placebo for post-exposure prophylaxis of influenza in household contacts. Eligible participants, who were household members who did not have influenza and were in contact with an influenza-infected index patient, were randomly assigned (1:1:1) to one of three groups: 20mg of laninamivir octanoate once daily for 2 days (LO-2), 20mg of laninamivir octanoate once daily for 3 days (LO-3), or a placebo. The primary endpoint was the proportion of participants who developed clinical influenza during a 10-day period. A total of 1711 participants were enrolled, and 1451 participants were included in the primary analysis. The proportion of participants with clinical influenza was 3.9 % (19/487) in the LO-2 group, 3.7 % (18/486) in the LO-3 group, and 16.9 % (81/478) in the placebo group (P<0.001 for each of the laninamivir octanoate group). The relative risk reductions, compared with the placebo group, were 77.0 % [95 % confidence interval (CI) 62.7–85.8] and 78.1 % (95 % CI 64.1–86.7 %) for the LO-2 and LO-3 groups, respectively. The incidences of adverse events in the laninamivir octanoate groups were similar to that in the placebo group. The inhalation of 20mg of laninamivir octanoate once daily for 2 or 3 days was well tolerated and effectively prevented the development of influenza in household contacts

Effect of Lubrication and Forging Load on Surface Roughness, Residual Stress, and Deformation of Cold Forging Tools

Cold forging is a metal forming that which uses localized compressive force at room temperature. During the cold forging process, the tool is subjected to extremely high loads and abrasive wear. Lubrication plays an important role in cold forging to improve product quality and tool life by preventing direct metallic contact. Surface roughness and residual stress also greatly affects the service life of a tool. In this study, variations in surface roughness, residual stress, and specimen deformation with the number of cold forging cycles were investigated under different forging conditions. Specimens that were made of heat-treated SKH51 (59-61 HRC), a high-speed tool steel with a polished working surface, were used. The specimens were subjected to an upsetting process. Compressive residual stress, surface roughness, and specimen deformation showed a positive relationship with the number of forging cycles up to a certain limit and became almost constant in most of the forging conditions. A larger change in residual stress and surface roughness was observed at the center of the specimens in all the forging conditions. The effect of the magnitude of the forging load on the above discussed parameters is large when compared to the effect of the lubrication conditions