Topology optimization has been successful in many industries, including the machine industry. However, two problems appear when topology optimization is applied to unsteady oscillation problems. First, a great deal of computational memory is required, because the adjoint equation for topology optimization must be solved. Second, numerous high-density elements are distributed at the load point of the cantilever beam model. In this study, the first problem is solved by changing the performance function and applying it to the maximization or minimization proble. We attempted to solve the second problem by applying the result from the steady problem to the initial conditions of the unsteady oscillation problem. In this paper we describe the optimal shapes, show the displacement waveform at a point and the stress distribution at a time, and discuss the usefulness of the research results.
The byproduct of MOE-1-mediated rubber decomposition is an insoluble residue. We aimed to establish a method to utilize this residue as a biomass resource. We investigated the effects of rubber residues on the growth and nisin productivity of Lactococcus lactis NBRC 12007. Altering the concentration ratio of complete medium supplemented with glucose (CMG) (for the cultivation of NBRC 12007) to the hydrophobic fraction of rubber residues changed both growth and nisin productivity. When the rubber residue concentration was higher, nisin activity was significantly boosted, whereas bacterial growth was not. Growth and nisin activity of NBRC 12007 were proportional to the concentration of CMG. Nisin-stimulating effects reached a stationary phase at a rubber residue concentration of 6–7 mg/L. In diluted CMG, rubber residues could stimulate bacterial growth but not nisin activity. Overall, the findings suggested that the ratio of rubber residue concentration to that of the medium affects bacterial metabolism.
Magnesium is light weight and has excellent bioabsorbability. Therefore, it is expected to be used as a biomaterial in the medical field. However, commercially available pure magnesium contains impurities such as iron, which promotes corrosion in the body. Ultra high purity magnesium is required to keep magnesium in the body for a long time. In addition, it is difficult to put it into practical use in a wide range because the strength is insufficient only with ultra high purity magnesium. Therefore, it was thought that forging would improve the strength and mechanical properties. Therefore, in this study, we investigated the production of ultra high purity magnesium sheet material by vacuum distillation, extrusion and forging. The purity of the prepared magnesium sheet was 99.999% or more, the tensile strength of the forged material was larger than that of the extruded material, and the elongation was smaller than that of the extruded material. It was also confirmed by EBSD (Electron Back Scatter Diffraction Patterns) observation that the extruded material had a texture and that the crystal grains of the forged material were refined.
During semiconductor manufacturing, ions are injected into SiC, which is a common substrate material. Conventional ion-injection methods require high voltage to accelerate ions. This voltage can be decreased using multi-charged ions. In our laboratory, we can achieve ion injection via an electron cyclotron resonance ion source, which is relatively inexpensive compared with other ion sources and capable of generating multi-charged ions. The present research was conducted to improve the production rate of Ar7+, which has an ionization energy close to that of Al4+, and generate aluminum ions. The ion-extraction voltage and confinement time were optimized by adjusting the magnetic field in the chamber. The generation of aluminum ions could be confirmed using a sputtering source, and the usefulness of the latter was validated via the formation of the former. Research results were shared with plural KOSENs and the Nagaoka University of Technology students through Zoom, and we successfully confirmed the educational effect of the model core curriculum and development of the general-purpose abilities of the students.
It is necessary to guarantee the accuracy of measuring machines in the manufacturing industry. The 3D optical coordinate measuring systems (hereinafter referred to as “3D optical CMS”) has become increasingly prevalent in industrial applications. The 3D optical CMS comprised a projector and a stereo camera uses point cloud data to accurately measure complex shapes and builds the shapes to be measured using a polygon mesh. However, when using the 3D optical CMS, measurement errors and measurement variabilities can occur owing to the influence of the surface characteristics of the target objects. Therefore, methods to guarantee the measurement reliability of the 3D optical CMS, even under the varying surface characteristics of the target objects, should be developed. The surface characteristics include color, glossiness, roughness, and fluorescence. In this study, the authors focus on surface color and research the measurement errors and the measurement variabilities during the measurements of target objects with different surface colors. Generally, the 3D optical CMS is used with a calibration gauge for performance evaluation and inspection. A datum ball, ball bar, and step gauge are one of the typical calibration gauges. However, these calibration gauges cannot evaluate the influence of the surface color of the target object on the measurement results. To fabricate calibration gauges for different surface colors is difficult, and if calibration gauges with colors are fabricated by painting or processing, characteristics other than surface color cannot be retained. Therefore, this study aims to establish a new evaluation method for evaluating the influence of the surface color and researches the possibility of substituting the reflected light from the surface of the target object (hereinafter referred to as “target object surface”) with light transmitted from a color filter. If the reflected light from the target object surface is substituted with transmitted light from the color filter, users of the 3D optical CMS does not need to fabricate several colored calibration gauges to evaluate the influence of the surface color on the measurement results. To the best of our knowledge, this approach has not been considered in previous studies on the 3D optical CMS. The proposed approach is validated based on comparisons of the measurement results obtained using color scheme cards and color filters.
In recent years, the automation of machine tools has progressed and the change of tools has also been automated. A tool is generally attached by using a female taper of machine tool. The maintenance of the female taper is periodically performed because tools are frequently changed. However, sensory inspection is still used in the maintenance of inner surface of female tapers. This maintenance method depends on the skill and sense of the craftsman and requires a lot of inspection time. Thus, a maintenance method based on sensory inspection hinders the promotion of automation at manufacturing job sites. Therefore, we propose a new measurement method to revolutionize the current one. In the proposed method, the depth of the wear area is quantitatively measured using the difference in color intensity caused by the difference in paint film thickness. Thus, using this method, the depth of the wear area can be easily measured by simply applying paint to the object and acquiring an image thereafter. In order to verify the resolution of the proposed method, an experiment was conducted on an experimental specimen with a known amount of wear. The experimental results indicated that the proposed method was capable of measuring at sub-micron resolution.