O avanço dos drones.

Parece até coisa de ficção científica saída das telas de cinema. E era bem isso algum tempo atrás. Hoje, porém, deixou de ser fantasia, mas manteve o caráter científico, com uma nova dimensão prática. Para espanto de muita gente, é cada vez maior o número de aeronaves não tripuladas sobrevoando as lavouras brasileiras. Quem vê pode pensar se tratar de um brinquedo ou hobby, como aeromodelismo. No entanto, é a mais recente ferramenta de apoio para agricultura de precisão, diferencial importante considerando o desafio de produzir cada vez mais, com eficiência e sustentabilidade.bitstream/item/114141/1/cpamt-2014-shozo-drones.pd

IGBT chip current imaging system by scanning local magnetic field

An IGBT / power diode current distribution imaging system was demonstrated. This system can capture current redistribution or oscillation inside or among chips on a DBC-level sub-module. It can perform failure analysis of power semiconductors by detecting problems such as nonuniform current distribution between bonding wires. The system scans the chip’s shape using a laser sensor and then records the local magnetic field near the bonding wire using a 4-axis robot coil sensor. The coil sensor has two pair of Cu patterned spiral coils symmetrically arranged on both sides of a 60-μm-thick polyimide film. The system enables the analysis of destructive current concentrations of the entire chip, among chips or a part of the chip under high current or high voltage switching conditions, without making any changes or disassembling the chip connections.24th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis. Schedule, September 30-October 4, 2013, Venue, Arcachon, Franc

Perpendicular exchange bias and magneto-electric control using Cr₂O₃(0001) thin film

Antiferromagnets themselves do not generate either stray fields or spontaneous magnetization. However, if an antiferromagnet is coupled with a ferromagnet, unique and useful characteristics appear. Exchange bias is one such characteristic that is utilized in spintronic devices like spin-valve films. To date, exchange bias has been used to induce static effects in devices; however, the exchange bias has not been switchable in these devices. Recently, switchable exchange bias has been developed using Cr₂O₃, which exhibits a magnetoelectric effect in an antiferromag-netic layer. The promising features of this effect are (1) the strength of the exchange bias is high and its direction is perpendicular to the film, and (2) the switching is triggered by an electric field. In this overview, we will summarize our recent results on the unique temperature dependence of high, perpendicular exchange bias and magnetoelectric switching of the induced perpendicular exchange bias.Y.Shiratsuchi, R.Nakatani, Perpendicular exchange bias and magneto-electric control using Cr₂O₃(0001) thin film. Materials Transactions 57, 781 (2016); https://doi.org/10.2320/matertrans.ME201506

Dominant factor of zero-field-cooled magnetization in discontinuous Fe films

The zero-field-cooled (ZFC) magnetization under the various field and temperature conditions has been investigated using the discontinuous Fe films. Among the various factors influencing the ZFC magnetization, it is found that either the thermal relaxation or the Langevin behavior dominates the ZFC magnetization, depending on the energy barrier distribution which is altered by the growth temperature. The peak temperature of ZFC magnetization follows the Néel-Brown model for the narrower energy barrier distribution. With broadening the energy barrier distribution for the higher growth temperature, the Langevin behavior of thermally fluctuated particles becomes dominant. The change of energy barrier distribution, namely, the dominant factor of ZFC magnetization, is explained by the broadening of size distribution and the degradation of crystallinity with increasing growth temperature. For both cases, we estimate the superparamagnetic blocking temperature TB and obtain the effective magnetic anisotropy and the effective volume from the field dependence of TB. From the obtained values, we show the presence of interparticle interaction for the Fe grown at 323 K, and discuss the effective magnetic anisotropy of randomly oriented particles grown above 573 K.Y.Shiratsuchi, M.Yamamoto, Dominant factor of zero-field-cooled magnetization in discontinuous Fe films. Physical Review B - Condensed Matter and Materials Physics 76, 144432 (2007); https://doi.org/10.1103/PhysRevB.76.144432

Agricultura de precisão e alguns aspectos sobre o manejo sítio-específico do nitrogênio em sistemas agrícolas.

bitstream/item/26440/1/Alvaro.pd

Contribution of Langevin behavior to the low temperature maximum in zero-field cooled magnetization of the discontinuous Fe films

The dominant factor of low temperature maximum of zero-field cooled (ZFC) magnetization has been investigated using a discontinuous ultrathin Fe film which is superparamagnetic at room temperature. The peak temperature of ZFC magnetization increases with increasing magnetic field strength, contrary to the Ǹel-Brown model. It is explained by the Langevin behavior of superparamagnetic particles dominating the low temperature maximum of ZFC magnetization due to the wide energy barrier distribution. For the case, the peak temperature should not be a good estimation of the blocking temperature since thermal activation of magnetization does not have a significant role in the low temperature maximum of ZFC magnetization.Yu Shiratsuchi, Ryoichi Nakatani, and Masahiko Yamamoto, Journal of Applied Physics 103, 07B503 (2008); https://doi.org/10.1063/1.2830948

畜産製品の品質因子としての香気ならびに異臭に関する研究

第1章 緒論 第2章 ソーセージの香りとその劣化に関する研究 第3章 脱脂粉乳の香気ならびに異臭に関する研究 第4章 総括Made available in DSpace on 2012-09-06T04:49:27Z (GMT). No. of bitstreams: 4 shiratsuchi1.pdf: 13139625 bytes, checksum: c30244eca88d25216c67c6282cbbaa8a (MD5) shiratsuchi2.pdf: 12542002 bytes, checksum: 2c8506ecbeb96f9f08a77279aa1833fe (MD5) shiratsuchi3.pdf: 9009165 bytes, checksum: 836ccb50b37c9a13bf78ef79883caa07 (MD5) shiratsuchi4.pdf: 7845524 bytes, checksum: 28bc10f23b8a3a684bc713c5a19b4a7d (MD5) Previous issue date: 1994-03-25主1-参

Determinação de ph e potássio em solos do meio norte de mato grosso utilizando eletrodos seletivos de íons

Amostragens de solo em grades regulares na agricultura de precisão são comumente utilizadas comercialmente em campos na região meio norte de Mato Grosso com sucesso. Porém, a confiabilidade dos mapas depende muito da densidade amostral, sendo mais confiáveis quando são mais intensivamente amostrados. Além da limitação técnica da utilização da krigagem com poucos pontos, existe uma necessidade de baratear o custo laboratorial de amostragens intensas. Neste sentido, o objetivo desde trabalho foi determinar o teor de pH e potássio em solos utilizando eletrodos seletivos de íons e também realizar uma comparação de mapas gerados por amostras laboratoriais convencionais comparadas com amostras medidas com eletrodos seletivos de íons. Foram realizadas amostragens em grades regulares de 4 ha em talhões no meio norte de Mato Grosso tentando cobrir uma amplitude de solos representativos da região, sendo realizadas 9 subamostras em cada 4 ha. As amostras foram enviadas para laboratório comercial e também realizadas medidas diretas com eletrodos de íons seletivos em bancada. Resultados preliminares mostram boas correlações entre os métodos, sendo r=0.56 e 0.61, para pH e potássio, respectivamente. Comparações espaciais mostram que além da similaridade entre os mapas houve uma tendência de suavização dos valores para medições feitas com os eletrodos, mostrando mais coerência das manchas dos teores no solo

Magnetoelectric induced switching of perpendicular exchange bias using 30-nm-thick Cr₂O₃ thin film

Magnetoelectric (ME) effect is a result of the interplay between magnetism and electric field and now, it is regarded as a principle that can be applied to the technique of controlling the antiferromagnetic (AFM) domain state. The ME-controlled AFM domain state can be read out by the magnetization of the adjacent ferromagnetic layer coupled with the ME AFM layer via exchange bias. In this technique, the reduction in the ME layer thickness is an ongoing challenge. In this paper, we demonstrate the ME-induced switching of exchange bias polarity using the 30-nm thick ME Cr₂O₃ thin film. Two typical switching processes, the ME field cooling (MEFC) and isothermal modes, are both explored. The required ME field for the switching in the MEFC mode suggests that the ME susceptibility (α₃₃) is not deteriorated at 30 nm thickness regime. The isothermal change of the exchange bias shows the hysteresis with respect to the electric field, and there is an asymmetry of the switching field depending on the switching direction. The quantitative analysis of this asymmetry yields α₃₃ at 273 K of 3.7 ± 0.5 ps/m, which is comparable to the reported value for the bulk Cr₂O₃.Y.Shiratsuchi, Y.Tao, K.Toyoki, R.Nakatani, Magnetoelectric induced switching of perpendicular exchange bias using 30-nm-thick Cr₂O₃ thin film. Magnetochemistry 7, 36 (2021); https://doi.org/10.3390/magnetochemistry7030036

Effect of substrate inclination on the magnetic anisotropy of ultrathin Fe films grown on Al₂ O₃(0001)

We have investigated the effect of substrate inclination on the in-plane magnetic anisotropy of ultrathin Fe films grown on Al₂O₃(0001). For Fe films grown on flat Al₂O₃ substrates, no preferred direction of magnetization exists in the film plane due to the three equivalent epitaxial orientations of Fe(110) that form. However, for Fe grown on an inclined Al₂O₃ substrate, a uniaxial anisotropy appears that is parallel to the step edges. The anisotropy increases in magnitude with decreasing Fe thickness and growth temperature, and as the surface morphology changes from being rough to being smooth. We attribute the uniaxial anisotropy to the effective demagnetization field caused by the surface corrugation.Yu Shiratsuchia, Yasushi Endo, and Masahiko Yamamoto, Bader, S. D, Journal of Applied Physics 97, 10J106 (2005); https://doi.org/10.1063/1.1850075