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.

Continuous static recrystallization in ultrafine-grained copper processed by multi-directional forging

Abstract: Annealing processes in copper, processed by multi-directional forging to strains of ɛ = 0.4–6.0 at 300 K, were studied at 503–573 K. Strain-induced ultrafine-grained copper shows mainly grain coarsening behaviour, which is categorized in three stages, i.e. (1) an incubation period, (2) a rapid and limited grain growth and finally (3) a classical (normal) grain growth. That is, in situ or continuous static recrystallization (cSRX) takes place in stages 1 and 2. The annealing characteristics and the mechanisms of cSRX are discussed with reference to those of conventional discontinuous SRX (dSRX).

A Wearable Haptic Display to Present the Gravity Sensation - Preliminary Observations and Device Design

Abstract: We propose a wearable, ungrounded haptic display that presents the realistic gravity sensation of a virtual object We focused on the shearing stress on the fingerpads duo to the weight of the object, and found that the deformation of the fingerpads can generate the reliable gravity sensation even when the proprioceptive sensation on the wrist or arm is absent This implies that a non-grounded gravity display can be realized by reproducing the fingerpad deformation According to our observations, we had evaluation tests for device design We implemented the prototype device which has simple structure using dual motors, and then evaluated the recognition ability of the gravity sensation presented on operator's fingerpads with this method

Additive Engineering to Grow Micron-Sized Grains for Stable High Efficiency Perovskite Solar Cells

Abstract: A high-quality perovskite photoactive layer plays a crucial role in determining the device performance. An additive engineering strategy is introduced by utilizing different concentrations of N,1-diiodoformamidine (DIFA) in the perovskite precursor solution to essentially achieve high-quality monolayer-like perovskite films with enhanced crystallinity, hydrophobic property, smooth surface, and grain size up to nearly 3 µm, leading to significantly reduced grain boundaries, trap densities, and thus diminished hysteresis in the resultant perovskite solar cells (PSCs). The optimized devices with 2% DIFA additive show the best device performance with a significantly enhanced power conversion efficiency (PCE) of 21.22%, as compared to the control devices with the highest PCE of 19.07%. 2% DIFA modified devices show better stability than the control ones. Overall, the introduction of DIFA additive is demonstrated to be a facile approach to obtain high-efficiency, hysteresis-less, and simultaneously stable PSCs.

Origin of the material dependence of T c in the single-layered cuprates

Abstract: In order to understand the material dependence of ${T}_{c}$ within the single-layered cuprates, we study a two-orbital model that considers both ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and ${d}_{{z}^{2}}$ orbitals. We reveal that a hybridization of ${d}_{{z}^{2}}$ on the Fermi surface substantially affects ${T}_{c}$ in the cuprates, where the energy difference $\ensuremath{\Delta}E$ between the ${d}_{{x}^{2}\ensuremath{-}y2}$ and the ${d}_{{z}^{2}}$ orbitals is identified to be the key parameter that governs both the hybridization and the shape of the Fermi surface. A smaller $\ensuremath{\Delta}E$ tends to suppress ${T}_{c}$ through a larger hybridization, whose effect supersedes the effect of diamond-shaped (better-nested) Fermi surface. The mechanism of the suppression of $d$-wave superconductivity due to ${d}_{{z}^{2}}$ orbital mixture is clarified from the viewpoint of the ingredients involved in the Eliashberg equation, that is, the Green's functions and the form of the pairing interaction described in the orbital representation. The conclusion remains qualitatively the same if we take a three-orbital model that incorporates the Cu $4s$ orbital explicitly, where the $4s$ orbital is shown to have an important effect of making the Fermi surface rounded. We have then identified the origin of the material and lattice-structure dependence of $\ensuremath{\Delta}E$, which is shown to be determined by the energy difference $\ensuremath{\Delta}{E}_{d}$ between the two Cu $3d$ orbitals (primarily governed by the apical oxygen height) and the energy difference $\ensuremath{\Delta}{E}_{p}$ between the in-plane and apical oxygens (primarily governed by the interlayer separation $d$).