Compositional Dependence of Normal Spectral Emissivity of Molten Cu-Fe Alloy

Metallurgical and Materials Transactions B - Normal spectral emissivity of molten Cu-Fe alloy with different compositions was measured at the wavelength of 807 nm using an electromagnetic...     

基于累积损伤理论的土石坝地震永久变形分析

以龙冈的在不规则荷载作用下土体应变的累积损伤理论为基础,提出了基于累积损伤理论的土石坝地震永久变形分析方法。采用大型静力和动力三轴仪,对某土石坝筑坝材料的静动变形特性进行了试验研究,确定了筑坝材料的静力和动力应力应变关系、累积应变模型和相应的材料参数。利用该方法,分别对在日本2008年6月14日岩手—宫城内陆M7.2级地震作用下该土石坝的在建坝体和竣工后坝体的地震永久变形特性进行了研究。结果表明：在建坝体的坝内沉降计算值与现场实测值基本吻合,并且通过与其它土石坝实测值的比较,说明竣工后坝体的坝顶沉降预测值在合理范围之内。     

Palladium‐Catalyzed Three‐Component Reaction of 3‐(Tri‐n‐ butylstannyl)allyl Acetates,Aldehydes, and Triorganoboranes: An Alternative to the Carbonyl Allylation Using α,γ‐Substituted Allylic Tin Reagents

A three‐component reaction of 3‐(tri‐n‐butylstannyl)allyl acetates, aldehydes, and triorganoboranes in the presence of a palladium‐Xantphos catalyst system predominately gave (E)‐anti‐homoallylic alcohols with high diastereoselectivity and good to high levels of alkene stereocontrol. An efficient chirality transfer was observed when an enantioenriched substrate was employed. The reaction was initiated by the formation of an allylic gem‐palladium/stannyl intermediate, which subsequently underwent allylation of the aldehyde by an allyltributyltin followed by a coupling reaction of the in‐situ‐generated (E)‐vinylpalladium acetate with the triorganoborane.

     

The World robot summit disaster robotics category – achievements of the 2018 preliminary competition

The World Robot Summit is a robot Olympics and aims to be held in a different country every four years from 2020. The concept of the Plant Disaster Prevention challenge is daily inspections, checks, and emergency response in industrial plants, and in this competition, robots must carry out these types of missions in a mock-up plant. The concept of the Tunnel Disaster Response and Recovery challenge is emergency response to tunnel disasters, and is a simulation competition whereby teams compete to show their ability to deal with disasters, by collecting information and removing debris. The Standard Disaster Robotics challenge assesses, in the form of a contest, the standard performance levels of a robot that are necessary for disaster prevention and emergency response. The World Robot Summit Preliminary Competition was held at Tokyo Big Sight in October 2018, and 36 teams participated in the Disaster Robotics Category. UGVs and UAVs contended the merits of new technology for solving complex problems, using core technologies such as mobility, sensing, recognition, performing operations, human interface, autonomous intelligence etc., as well as system integration and implementation of strategies for completing missions, gaining high-level results.     

Chained aggregation model with minimum truncation error

A reduced–order model for a multi–input single–output or a single–input multi–output continuous system is proposed. The model is especially suitable for the case where accuracy in the high-frequency region is important. It also satisfies basic conditions for reduced-order models, such as uniqueness, stability, and a simple calculation requirement. Chained aggregation with the minimization of truncation errors introduces an internal system representation characterized by a system matrix of Hessenberg form and a diagonalized covariance matrix.     

Normal Spectral Emissivity Measurement of Molten Cu–Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

The normal spectral emissivity of molten Cu–Co alloy with different compositions was measured in the wavelength range of 780 nm to 920 nm and in the temperature range of 1430 K to 1770 K including the undercooled condition by an electromagnetic levitator superimposed with a static magnetic field. The emissivity was determined as the ratio of the radiance from a levitated molten Cu–Co droplet measured by a spectrometer to the radiance from a blackbody calculated by Planck’s law at a given temperature, where a static magnetic field of 2.5 T to 4.5 T was applied to the levitated droplet to suppress the surface oscillation and translational motion of the sample. We found little temperature dependence of the normal spectral emissivity of molten Cu–Co alloy. Concerning the composition dependence, the emissivity decreased markedly above 80 at%Cu and reached that of pure Cu, although its dependence was low between 20 at%Cu and 80 at%Cu. In addition, this composition dependence of the emissivity of molten Cu–Co alloy can be explained well by the Drude free-electron model.     

Synthesis of non-equilibrium phases in immiscible metals mechanically mixed by high pressure torsion

The structural changes in mechanically mixed metals of immiscible combinations of elements caused by bulk mechanical alloying (MA) through the use of high pressure torsion (HPT) were investigated in Ag–Ni and Nb–Zr systems. There was no alloying between Ag and Ni on atomic scale even after 100 rotations of HPT. On the other hand, the β-Zr phase started to appear after HPT 2 rotations in the Nb–Zr system, even though β-Zr is a high temperature phase. Further, Nb and Zr were completely mixed to form a bcc structured single phase after HPT 100 rotations. The sequence of alloying in the Nb–Zr system during HPT was discussed. These results clearly suggest that non-equilibrium phases can form in the Nb–Zr system by bulk MA by the use of HPT.     

Study of polarization phenomena in Schottky CdTe diodes using infrared light illumination

Schottky CdTe diode detectors suffer from a polarization phenomenon, which is characterized by degradation of the spectral properties over time following exposure to high bias voltage. This is considered attributable to charge accumulation at deep acceptor levels. A Schottky CdTe diode was illuminated with an infrared light for a certain period during a bias operation, and two opposite behaviors emerged. The detector showed a recovery when illuminated after the bias-induced polarization had completely progressed. Conversely, when the detector was illuminated before the emergence of bias-induced polarization, the degradation of the spectral properties was accelerated. Interpretation of these effects and discussion on the energy level of deep acceptors are presented.