University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Theoretical and experimental examination of near-field acoustic levitation

Abstract: A planar object can be levitated stably close to a piston sound source by making use of acoustic radiation pressure. This phenomenon is called near-field acoustic levitation [Y. Hashimoto et al., J. Acoust. Soc. Am. 100, 2057–2061 (1996)]. In the present article, the levitation distance is predicted theoretically by numerically solving basic equations in a compressible viscous fluid subject to the appropriate initial and boundary conditions. Additionally, experiments are carried out using a 19.5-kHz piston source with a 40-mm aperture and various aluminum disks of different sizes. The measured levitation distance agrees well with the theory, which is different from a conventional theory, and the levitation distance is not inversely proportional to the square root of the surface density of the levitated disk in a strict sense.

Information-Theoretic Approach to Optimal Differential Fault Analysis

Abstract: This paper presents a comprehensive analysis of differential fault analysis (DFA) attacks on the Advanced Encryption Standard (AES) from an information-theoretic perspective. Injecting faults into cryptosystems is categorized as an active at tack where attackers induce an error in operations to retrieve the secret internal information, e.g., the secret key of ciphers. Here, we consider DFA attacks as equivalent to a special kind of passive attack where attackers can obtain leaked information without measurement noise. The DFA attacks are regarded as a conversion process from the leaked information to the secret key. Each fault model defines an upper bound for the amount of leaked information. The optimal DFA attacks should be able to exploit fully the leaked information in order to retrieve the secret key with a practical level of complexity. This paper discusses a new DFA methodology to achieve the optimal DFA attack by deriving the amount of the leaked information for various fault models from an information-theoretic perspective. We review several previous DFA at tacks on AES variants to check the optimality of their attacks. We also propose improved DFA attacks on AES-192 and AES-256 that reach the theoretical limits.

Brillouin scattering study in the GaN epitaxial layer

Abstract: We have investigated the elastic properties of a GaN epitaxial layer on a sapphire substrate by Brillouin scattering in the backward and 90° scattering geometries. A sample of high optical quality grown by the two-flow MOCVD method with a complex structure of In 0.05 Ga 0.95 N(0.05 μm)/GaN(2 μm)/sapphire was used. The weak spectra were not simple due to the boundaries and the InGaN thin film. The elastic constants of GaN were estimated and compared with those obtained from X-ray diffraction.

Electric field control of Skyrmions in magnetic nanodisks

Abstract: The control of magnetic Skyrmions confined in a nanometer scale disk using electric field pulses is studied by micromagnetic simulation. A stable Skyrmion can be created and annihilated by an electric field pulse depending on the polarity of the electric field. Moreover, the core direction of the Skyrmion can be switched using the same electric field pulses. Such creation and annihilation of Skyrmions, and its core switching do not require any magnetic field and precise control of the pulse length. This unconventional manipulation of magnetic texture using electric field pulses allows a robust way of controlling magnetic Skyrmions in nanodiscs, a path toward building ultralow power memory devices.