钛与低碳钢的电阻点焊

采用电阻点焊方法对纯钛与低碳钢Q235进行焊接试验，利用扫描电子显微镜观察分析了熔核区组织特性，探讨了焊接电流对熔核尺寸和抗剪载荷的影响. 结果表明，受焦耳热的影响熔核直径随焊接电流的增加而增加，抗剪载荷则随焊接电流的增大而呈先升后降的变化趋势，焊接电流为8 kA时所得接头的抗剪载荷最大，约2.85 kN. 在钢侧熔核区观察到了靠近钢侧厚度约为30～50 μm的TiFe2+α-Fe共晶组织层和粗大TiFe柱状晶；钛侧熔核区主要由靠近钛侧约12 μm厚的TiFe+α-Ti共晶组织层和TiFe柱状晶构成，且观察到了宏观分层现象.     

Effects of CuO Addition on Electrical Properties of 0.6BiFeO3–0.4(Bi0.5K0.5)TiO3 Lead‐Free Piezoelectric Ceramics

0.6BiFeO₃–0.4(Bi_0.5K_0.5)TiO₃ (0.6BF–0.4BKT) ceramic samples with 0.0–4.0 mol% CuO were prepared by the solid‐state reaction. The CuO addition aided the densification of the samples and slightly increased the lattice constant. The relaxor‐like defuse dielectric peak of 0.6BF–0.4BKT became sharper with increasing the CuO content. Polarization–electric field curve of the undoped 0.6BF–0.4BKT was a pinched loop in the as‐sintered state, while that was a square hysteresis with a large remanent polarization of 48 μC/cm² after the thermal quenching, demonstrating a strong domain wall pinning due to defect dipoles. We found that the CuO addition up to 2.0 mol% facilitates the polarization switching in the as‐sintered samples to increase the remanent polarization and the piezoelectric d₃₃ coefficient. The results of the structural and electrical investigations suggested that the copper ion acts as a donor in 0.6BF–0.4BKT by compensating the potassium vacancy created by the evaporation of K₂O during the calcination and sintering processes.     

Robot motion design using bunraku emotional expressions – focusing on Jo-Ha-Kyū in sounds and movements*

One of the UNESCO intangible cultural heritages Bunraku puppets can play one of the most beautiful puppet motions in the world. The Bunraku puppet motions can express emotions without the so-called ‘Uncanny Valley.’ We try to convert these emotional motions into robot affective motions so that robots can interact with human beings more comfortable. In so doing, in the present paper, we present a robot motion design framework using Bunraku affective motions that are based on the so-called ‘Jo-Ha-Kyū,’ and convert a few simple Bunraku motions into a robot motions using one of deep learning methods. Our primitive experiments show that Jo-Ha-Kyū can be incorporated into robot motion design smoothly, and some simple affective robot motions can be designed using our proposed framework.     

Estimation of contact stiffness at interfaces in machine structures by a beam model on an elastic foundation

The dynamic properties of machine structures are significantly influenced by an interaction at the mating surfaces of machine elements. This interaction is called contact stiffness, and the development of a simple method for contact stiffness estimation is an important tribological objective. In this paper the contact stiffness is estimated by a beam model vibrating on an elastic foundation. The effects of clamping condition and mating surface topography on the contact stiffness obtained are quantitatively and accurately represented by experimental equations.     

Endoleak after endovascular graft repair of experimental aortic aneurysms: does coil embolization with angiographic "seal" lower intraaneurysmal pressure?

PURPOSE: To investigate the relation between endoleaks and intraaneurysmal pressure (IAP) and the effect of coil embolization in the management of endoleaks. METHODS: The infrarenal aorta of a dog (n = 15) was replaced by a polytetrafluoroethylene aneurysm containing a pressure transducer. Group I (n = 4) had untreated aneurysms. Group II (n = 4) had endovascularly excluded aneurysms without an endoleak. Group III (n = 7) had aneurysms excluded by means of grafts with a defect that represented the source of an endoleak. After 4 weeks of follow-up study, the endoleaks in group III dogs were subjected to coil embolization. Systolic IAP was measured daily and expressed as a ratio of systolic blood pressure obtained from a forelimb cuff. Arteriography, duplex ultrasonography, and spiral contrast computed tomography were performed to evaluate endoleaks. RESULTS: In group I, the LAP remained close to systolic blood pressure (ratio of 0.96 +/- 0.06), whereas in group II the IAP ratio showed a decline to 0.34 +/- 0.16 (p = 0.0009 group I versus II). After an initial decrease, the IAP ratio in group III stabilized at 0.75 +/- 0.18 (p = 0.003, group II versus III). Aneurysms with an endoleak remained pulsatile with a pulse pressure of 30 +/- 16 mm Hg, which was less than that of untreated aneurysms (62 +/- 15 mm Hg; p < 0.0001 group I versus III). Arteriography and computed tomography revealed "sealing" of endoleaks after coil embolization, but IAP ratio did not decrease (0.76 +/- 0.14) after coil embolization. CONCLUSIONS: Incomplete endovascular aneurysm exclusion caused by an endoleak fails to reduce IAP ratio and may subject the aneurysm to a continued risk for rupture. Although coil embolization resulted in angiographic and computed tomographic sealing, it failed to reduce IAP ratio.     

Superconducting Coupling Nature at Grain Boundaries in Bi2Sr2CaCu2Ox Glass-Ceramics

Superconducting coupling nature at grain boundaries in Bi₂Sr₂CaCu₂O _x glass-ceramics consisting mainly of the low- T _c phase was first examined by measuring superconducting properties and temperature or ac field dependence of ac complex susceptibility. It was found from the ac loss peaks that superconducting coupling at grain boundaries was basically characterized by three types of weak links. The weak-link behaviors at grain boundaries depended strongly on cooling conditions after annealing and annealing time and temperature. Particularly, it was found that the weak links at grain boundaries were improved by prolonged annealing at 840°C. The furnace-cooled glass-ceramics obtained by annealing at 820° or 840°C for about 200 h exhibited a critical transport current density (77 K, zero magnetic field) of about 200 A/cm².     

Synthesis of Sintered Diamond with High Electrical Resistivity and Hardness

Diamond and diamond-ultrafine Co powder mixtures were sintered at 7.7 GPa and 1800° to 2000°C. A well-sintered body with a fine-grained homogeneous microstructure, high hardness, and high electrical resistivity was produced when a diamond-5 vol% Co powder mixture was used as the starting material.     

Preparation of Porous Cr3C2 Grains with Cr2O3

Porous Cr₃C₂ grains (∼300 to 500 μm) with ∼10 wt% of Cr₂O₃ were prepared by heating a mixture of MgCr₂O₄ grains and graphite powder at 1450° to 1650°C for 2 h in an Al₂O₃ crucible covered by an Al₂O₃ lid with a hole in the center. The porous Cr₃C₂ grains exhibited a three-dimensional network skeleton structure. The mean open pore diameter and the specific surface area of the porous grains formed at 1600°C for 2 h were ∼3.5 (μm and ∼6.7 m²/g, respectively. The present work investigated the morphology and the formation conditions of the porous Cr₃C₂ grains, and this paper will discuss the formation mechanism of those grains in terms of chemical thermodynamics.     

Insights from ab initio molecular dynamics simulations for a multicomponent oxide glass

It remains a challenge to establish structural models of multicomponent oxide glass systems. In this study, we have investigated 68.3SiO₂–16.1B₂O₃–4.2Al₂O₃–11.4Na₂O glass and melt structures by ab initio molecular dynamics (AIMD) simulations. The atomic configurations obtained from AIMD simulations were validated against ¹⁷O solid‐state NMR spectrum under 24.0 T and neutron diffraction data, and excellent agreement was achieved. The bond lengths, angles, and coordination geometries were statistically analyzed for each atomic species. Here we particularly address the role of minor atomic species such as five‐coordinate Si (Si^V) and Al (Al^V). The Si^V–O bond lengths and O–Si^V–O angle distribution in the glass indicated 1.718 Å and three peaks at 90°, 120°, and 175°, which are assigned to a coordination geometry of the trigonal bipyramidal structure. Ring statistic analysis revealed that Si^V and Al^V were found to preferentially contribute to the formation of small ring sizes.     

Rapid Desensitization of Lipolysis in the Visceral and Subcutaneous Adipocytes of Rats

In adipocytes, short and long term stimulation of β adrenergic receptors (βAR) induces the desensitization to catecholamines, leading to a decrease in the intracellular accumulation of cAMP, but the roles played by this in lipolysis is not clear. In this study, we assessed the catecholamine-induced desensitization of lipolysis and compared this in adipocytes isolated from visceral and subcutaneous fat tissues of rats. When adipocytes were pretreated with isoproterenol (ISO), the norepinephrine (NE)-induced lipolysis was significantly reduced dose- and time-dependently. A similar reduction of the lipolytic response was also found in NE-, dobutamine-, terbutaline- or BRL37344-induced lipolysis. The ISO- and each βAR agonist-induced lipolysis in the visceral fat was not only higher than in the subcutaneous fat, but also markedly reduced by ISO- or NE-pretreatment. These results showed that short-term treatment of three subtypes of βAR by each agonist induces a rapid reduction in the lipolytic response to βAR stimulation. This suggests some common mechanism for the rapid desensitization of βAR-agonist-induced lipolysis, in contrast with previous reports on the characteristics of βAR subtypes. In addition, the regional difference of adipose tissue not only in inducing lipolysis but also in rapid desensitization was also apparent.