リモート型ホットワイヤ装置の開発と新規MEMSプロセスへの応用

要約のみTohoku University田中秀治課

An analysis of half elliptical surface crack propagation phenomenon with smoothed particle hydrodynamics method

The smoothed particle hydrodynamics (SPH) method was applied to the problem of fatigue crack propagation. The stress singularity characteristics at the crack tip and the stress intensity factor were compared between the SPH results and the reference values. The result of half elliptical surface crack propagation analysis showed smooth crack propagation history and the shape of the analyzed fracture surface was close to that achieved by test. Accordingly, it is concluded that the SPH is a useful tool to analyze the linear elastic fracture mechanics and the fatigue crack propagation

An analysis of three-dimensional non-planar crack propagation phenomenon with smoothed particle hydrodynamics method

In the present study, the non-planar crackpropagation problems in the 3D body are solved, extending our previous study on the smoothed particle hydrodynamics (SPH) method applied to the fatigue crack propagation of the planar cracks in the 3D body. To solve the propagation of the non-planar crack, the crack front particles are given the information of the slope and the position of the crack surface in addition to the crack length. To confirm the validity of the proposed method, a fatigue test of the CT specimen with an additional horizontal hole is carried out and the result is compared with the computed one successfully

Mechanically rational forms of curved surface structures shaped from the uniform strain elements

The paper proposes a method for finding mechanically rational and practical forms of curved surface by using the uniform strain elements. Numerical methods for form finding already published give exact solutions but the application is restricted to the problems with the conditions possible to form a minimal surface. This is because the methods use the mechanical model without material stiffness but with only the geometric stiffness of isotropic tension. When the uniform strain elements composing a structural form have even isotropic strain in all over the form, the form is an isotropic tension form. Since the uniform strain element has the material stiffness, the method can stably yield a form with the strains varying as narrowly as possible in the curved surface under the condition impossible to shape a minimal surface

Facile synthesis of fluorescent hetero[8]circulene analogues with tunable solubilities and optical properties

Hetero[8]circulenes are an interesting class of polycyclic heteroaromatic molecules having rigid and planar structures, which are promising in light of their potential applications for OLEDs, OFETs and so forth. Although their synthetic methods have been developed in some specific cases, a facile synthetic protocol of novel hetero[8]circulenes with tunable properties is highly desirable. We herein report the unexpected formation of methoxy-substituted quasi-aza[8]circulene and its conversion into unprecedented triazaoxa[8]circulene. The structures and optical properties were comparatively studied. Remarkably, triazaoxa[8]circulene is highly soluble in THF, acetone and DMSO mainly because of effective hydrogen-bonding of the NH moieties to these solvents. Their highly soluble nature in various solvents enabled us to study the solvent effects of these molecules. In particular, triazaoxa[8]circulene displays a high fluorescence quantum yield of 0.72 in DMSO. Furthermore, enantiomeric separation of highly distorted quasi-aza[8]circulene was successfully achieved by chiral HPLC. Thus, these novel hetero[8]circulene derivatives are practically useful fluorescent nanographene-like molecules with intriguing optical properties

Graph Signal Restoration Using Nested Deep Algorithm Unrolling

Graph signal processing is a ubiquitous task in many applications such as sensor, social, transportation and brain networks, point cloud processing, and graph neural networks. Graph signals are often corrupted through sensing processes, and need to be restored for the above applications. In this paper, we propose two graph signal restoration methods based on deep algorithm unrolling (DAU). First, we present a graph signal denoiser by unrolling iterations of the alternating direction method of multiplier (ADMM). We then propose a general restoration method for linear degradation by unrolling iterations of Plug-and-Play ADMM (PnP-ADMM). In the second method, the unrolled ADMM-based denoiser is incorporated as a submodule. Therefore, our restoration method has a nested DAU structure. Thanks to DAU, parameters in the proposed denoising/restoration methods are trainable in an end-to-end manner. Since the proposed restoration methods are based on iterations of a (convex) optimization algorithm, the method is interpretable and keeps the number of parameters small because we only need to tune graph-independent regularization parameters. We solve two main problems in existing graph signal restoration methods: 1) limited performance of convex optimization algorithms due to fixed parameters which are often determined manually. 2) large number of parameters of graph neural networks that result in difficulty of training. Several experiments for graph signal denoising and interpolation are performed on synthetic and real-world data. The proposed methods show performance improvements to several existing methods in terms of root mean squared error in both tasks