Nagoya Institute of Technology

About: Nagoya Institute of Technology is a education organization based out in Nagoya, Japan. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 10766 authors who have published 19140 publications receiving 255696 citations. The organization is also known as: Nagoya Kōgyō Daigaku & Nitech.

Anomalous temperature dependence of the electrical resistivity in binary and pseudobinary alloys based on Fe3Si

Abstract: The electrical resistivity of binary Fe-Si and ternary (${\mathrm{Fe}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{M}}_{\mathit{x}}$${)}_{3}$Si alloys, with 3d transition-metal elements M=Ti, V, Cr, Mn, Co, and Ni, has been measured over the temperature range from 4.2 to 1373 K. The resistivity for M=Ti, V, Cr, and Mn shows an anomalous temperature dependence: an occurrence of a resistance maximum near the Curie point ${\mathit{T}}_{\mathit{C}}$ and a negative resistivity slope above ${\mathit{T}}_{\mathit{C}}$. The tendency of the negative temperature dependence of the resistivity increases markedly with increasing composition, accompanying a sharp reduction in ${\mathit{T}}_{\mathit{C}}$. In contrast, the resistivity curves for M=Co and Ni exhibit almost the same form as that of ${\mathrm{Fe}}_{3}$Si, regardless of the Co or Ni composition, so that the resistivity above ${\mathit{T}}_{\mathit{C}}$ remains almost constant or decreases slightly. The negative temperature dependence induced by M substitution appears only when the resistivity estimated in the paramagnetic state is above 150 \ensuremath{\mu}\ensuremath{\Omega} cm, and the higher paramagnetic resistivity causes the lower temperature coefficient of the resistivity. It is concluded that the resistance maximum in (${\mathrm{Fe}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{M}}_{\mathit{x}}$${)}_{3}$Si is closely related to an extremely large spin-disorder scattering, in addition to a high residual resistivity.

On the averaging area for incident power density for human exposure limits at frequencies over 6 GHz

Abstract: Incident power density is used as the dosimetric quantity to specify the restrictions on human exposure to electromagnetic fields at frequencies above 3 or 10 GHz in order to prevent excessive temperature elevation at the body surface. However, international standards and guidelines have different definitions for the size of the area over which the power density should be averaged. This study reports computational evaluation of the relationship between the size of the area over which incident power density is averaged and the local peak temperature elevation in a multi-layer model simulating a human body. Three wave sources are considered in the frequency range from 3 to 300 GHz: an ideal beam, a half-wave dipole antenna, and an antenna array. 1D analysis shows that averaging area of 20 mm × 20 mm is a good measure to correlate with the local peak temperature elevation when the field distribution is nearly uniform in that area. The averaging area is different from recommendations in the current international standards/guidelines, and not dependent on the frequency. For a non-uniform field distribution, such as a beam with small diameter, the incident power density should be compensated by multiplying a factor that can be derived from the ratio of the effective beam area to the averaging area. The findings in the present study suggest that the relationship obtained using the 1D approximation is applicable for deriving the relationship between the incident power density and the local temperature elevation.

Contact force and scanning velocity during active roughness perception.

Abstract: Haptic perception is bidirectionally related to exploratory movements, which means that exploration influences perception, but perception also influences exploration. We can optimize or change exploratory movements according to the perception and/or the task, consciously or unconsciously. This paper presents a psychophysical experiment on active roughness perception to investigate movement changes as the haptic task changes. Exerted normal force and scanning velocity are measured in different perceptual tasks (discrimination or identification) using rough and smooth stimuli. The results show that humans use a greater variation in contact force for the smooth stimuli than for the rough stimuli. Moreover, they use higher scanning velocities and shorter break times between stimuli in the discrimination task than in the identification task. Thus, in roughness perception humans spontaneously use different strategies that seem effective for the perceptual task and the stimuli. A control task, in which the participants just explore the stimuli without any perceptual objective, shows that humans use a smaller contact force and a lower scanning velocity for the rough stimuli than for the smooth stimuli. Possibly, these strategies are related to aversiveness while exploring stimuli.