Plane thermal transpiration of a rarefied gas in the presence of gravitation

Plane thermal transpiration of a rarefied gas that flows horizontally in the presence of gravitation is studied based on the Boltzmann equation. Assuming that the temperature gradient along the walls is small, the asymptotic analysis for a slow variation in the flow direction is conducted. The semi-analytical solution that is valid for arbitrary values of the mean free path and the gravitational strength is derived, and the problem is reduced to solving the spatially one-dimensional Boltzmann equation. This reduced problem is solved numerically for a hard-sphere molecular gas for small values of gravitational strength, and the behavior of the flow is studied based on the numerical solution. The effect of weak gravitation is no longer negligible when the gas is so rarefied that the mean free path is comparable to the maximum range that the molecules travel along the parabolic path within the channel. This phenomenon has been observed in the plane Poiseuille flow of a highly rarefied gas, and a similar phenomenon also occurs in the plane thermal transpiration considered in the present paper.     

Effects of Si addition on mechanical properties of copper severely deformed by accumulative roll-bonding

Effects of Si addition on mechanical properties of severely deformed copper by accumulative roll-bonding (ARB) have been investigated. Tensile tests and strain-rate jump tests have been carried out at room temperature. For annealed coarse-grained polycrystals, the difference in yield stress σ _0.2 between pure copper and a Cu–1.64at.%Si alloy was only about 15 MPa while the difference became 170 MPa after the ARB process by six cycles. The strain-rate sensitivity m of pure copper increased with increasing the number N of the ARB cycles for N ≥ 5. However, the increase in m becomes less significant for Cu–Si alloys. These findings have been discussed in terms of thermally activated dislocation processes.     

Chemothermal pulverization: Crushing titanate crystals to obtain nanosized powders via high-temperature treatment

In this study, we investigated chemothermal pulverization (CTP) phenomena that are induced in titanate single crystals and ceramics by high-temperature treatment at approximately 1000℃ under reactive gas containing ammonia and oxygen and cause these materials to break down into nanosized powders. Structural characterization revealed that there were many nanosized voids formed in titanates during heat treatment for CTP, and subsequent analysis revealed that these voids were filled with nitrogen gas. These results indicated that CTP consisted of four steps: the in-diffusion of nitride ions from the surface to titanates, the deposition of nitrogen molecules (gas) inside the titanate crystals instead of nitride formation, the growth of voids by further nitrogen transport from the surface to voids, and, finally, the breakdown of the walls between voids to form nanopowders. Furthermore, we discussed the exact mechanism of CTP phenomena by examining the effect of doping into titanates on the progress of CTP and by conducting theoretical calculations for the simulation of nitrogen impurities in titanate lattices.     

尖端电机控制技术

本文报道了三菱电机公司前沿电机控制技术的开发态势,介绍了可为永磁同步电机提供高性能驱动,而不使用转子位置传感器的无传感器控制方法。接着介绍了感应电机产生的温度依赖性转矩的矢量控制方法。 1 永磁同步电机无传感器控制 永磁同步电机利用转子里的永磁铁产生磁通量,而转子是通过定子施加的同步旋转磁场驱动转子的。     

Location choice of multinational enterprises in China: Comparison between Japan and Taiwan

This paper explores the location choice of multinational enterprises (MNEs) in China, shedding special light on the role of agglomeration of same‐nationality firms. We examine how this role differs according to firms' productivity. Furthermore, we compare the location choice of Japanese and Taiwanese MNEs in China, taking into consideration that Taiwanese MNEs experience less uncertainty in investing in China due to Taiwan's linguistic and cultural advantages. When considering firms' productivity, we find that less productive Japanese firms prefer to locate close to larger same‐nationality agglomerations while there are no differences in location choices in the case of Taiwanese firms.     

Effect of compression overload on fatigue strength improved by ICR treatment

ICR (Impact Crack-closure Retrofit) treatment was developed for extending fatigue life of cracked steel structures by closing the fatigue crack opening. By applying the ICR treatment to as-welded condition, compressive stress remains at weld toe. Therefore, ICR treatment can be used for the improvement of fatigue strength of welded joint at the same level of the other fatigue strength improved techniques. If a compression overload is subjected after ICR treatment, however, the residual compressive stress at weld toe will shift the tensile stress region. Accordingly, improved fatigue strength of welded joints by ICR treatment will be reduced after the compression overloaded. In order to investigate the effect of the compression overload on fatigue strength improved by ICR treatment, fatigue tests of out-of-plane gusset specimens were carried out. As the results, fatigue strength improved by ICR treatment was hardly reduced under the compression overload condition of nominal stress of ?190 MPa.     

MoCl5在150 ℃室温离子液体中的电化学还原

研究150 ℃下采用二元室温离子液体中电化学还原五氯化钼制备金属钼。该室温离子液体是二(三氟甲基磺酸酰)亚胺锂(LiTFSI)和二(三氟甲基磺酸酰)亚胺铯(CsTFSI)的共晶熔体(共晶点组成：摩尔比为0.07:0.93; 共晶点温度为112 ℃)。循环伏安法结合SEM-EDAX和XPS 分析表明,在150 ℃可以在镍基板上电沉积得到金属钼。采用恒电流电解和脉冲电流电解的条件下,镀层的质量得到改善     

Physical Properties,Crystallization, and Thermal/Hydrolytic Degradation of Poly(L‐lactide)/Nano/Micro‐Diamond Composites

The effects of incorporated nano/micro‐diamond (NMD) on the physical properties, crystallization, thermal/hydrolytic degradation of poly(L ‐lactic acid) (PLLA) were investigated for a wide NMD concentration range of 0–10 wt.‐%. Incorporated NMD increased the tensile modulus and strength of PLLA films but decreased the elongation at break of PLLA films. Incorporated NMD accelerated the crystallization of PLLA during heating and cooling and increased the absolute crystallization enthalpy of PLLA films (except for an NMD concentration of 10 wt.‐% during cooling) but did not alter the crystallization mechanism. Incorporated NMD increased and decreased the thermal stability of PLLA films for NMD concentrations of 1–5 and 10 wt.‐%, respectively, and increased the hydrolytic degradation resistance of PLLA films.

     

Chiral Homobimetallic Palladium(II) Complexes Composed of Chirality-Organized Quinonediimines Bearing Amino Acid Moieties

The chirality-organized quinonediimine derivatives bearing amino acid moieties were demonstrated to react with 2 molar equiv. of Pd(OAc)₂, resulting in the formation of the chiral homobimetallic palladium(II) complexes. The crystal structures of the chiral conjugated complexes revealed the coordination of the quinonediimine nitrogen to a palladium center and a chiral propeller twist conformation of the π-conjugated backbone. The mirror image relationship of the CD signals around the quinonediimine moieties in acetonitrile was observed between l- and d-derivatives, indicating the preservation of the chirality-organized structures even in a solution.     

Current-reinforced random walks for constructing transport networks

Biological systems that build transport networks, such as trail-laying ants and the slime mould Physarum, can be described in terms of reinforced random walks. In a reinforced random walk, the route taken by ‘walking’ particles depends on the previous routes of other particles. Here, we present a novel form of random walk in which the flow of particles provides this reinforcement. Starting from an analogy between electrical networks and random walks, we show how to include current reinforcement. We demonstrate that current-reinforcement results in particles converging on the optimal solution of shortest path transport problems, and avoids the self-reinforcing loops seen in standard density-based reinforcement models. We further develop a variant of the model that is biologically realistic, in the sense that the particles can be identified as ants and their measured density corresponds to those observed in maze-solving experiments on Argentine ants. For network formation, we identify the importance of nonlinear current reinforcement in producing networks that optimize both network maintenance and travel times. Other than ant trail formation, these random walks are also closely related to other biological systems, such as blood vessels and neuronal networks, which involve the transport of materials or information. We argue that current reinforcement is likely to be a common mechanism in a range of systems where network construction is observed.