Co-Al二元系中的fcc/hcp马氏体相变和形状记忆效应

It is known that pure Co undergoes martensitic transformation from γ phase (fcc) to ε phase (hcp) by the movement of a/6<112> Shockley partial dislocations at around 400 ℃, however, there have been few systematic works on the SM effect in Co and Co-based alloys. In this study, the fcc/hcp martensitic transformation and the SM effect were investigated in Co-Al binary alloys(mole fraction of Al=0～16%).The γ/ε martensitic transformation temperatures were found from the DSC measurements to decrease with increasing Al content, while the transformation temperature hystereses were observed to increase from 60 ℃ at x(Al)=0 to 150 ℃at x(Al)= 16%. The SM effect evaluated by a conventional bending test was enhanced by the addition of Al over 4%(mole fraction) and Co-Al alloys containing over 10%(mole fraction) exhibit a good SM effect associated with the hcp →fcc reverse transformation above 200 ℃. The SM effect was significantly improved by precipitation ofβ (B2) phase and the maximal shape recovery strain of 2. 2% was obtained, which can be explained by precipitation hardening. The crystallographic orientations between theβ, ε and γ phases were also determined. Finally, the magnetic properties were investigated and it was found that the Curie temperature and saturation magnetization of Co-14% Al(mole fraction) are 690 ℃and 120 emu/g, respectively. It is concluded that the Co-Al alloys hold promise as new high-temperature and ferromagnetic SM alloys.     

A design scheme of discrete robust PID control systems and its application

PID controllers have been widely used in many chemical processes. Because they have only three control parameters, we can easily understand their physical meanings. However, it is difficult to tune their parameters in the case where the control system has uncertainties, for example, modeling errors, system fluctuation, and so on. Therefore, we propose a design scheme of discrete robust PID controllers in this paper. That is, we design a PID controller in connection with the generalized minimum variance control (GMVC) scheme, and present a scheme on how to design a weighting factor included in the GMVC criterion from the viewpoint of robust stability. Furthermore, we investigate the behavior of the proposed control scheme by applying it to an air pressure control system. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 77–83, 1999     

A holonic control system based on a universal learning network

A new control method is presented using the holonic concept on a universal learning network (ULN). The holonic concept was proposed by Arthur Koestler in 1905. Its aim is to harmonize entire systems with partial systems that have hierarchal structures. On the other hand, a ULN that models and controls large-scale complicated systems such as industrial plants and, economic, social, and life phenomena is proposed. In this paper, a holonic control system based on the holonic concept and ULN is presented. From simulation results from a nonlinear crane system, it has been proved that holonic control can harmonize the system rather than optimize it, which used to be the conventional method in control engineering.     

New Measurements of Wetting by Helium Mixtures

We have measured the contact angle of the ³He–⁴He interface on a sapphire window in the temperature range from 50 to 845 mK. Contrary to what had been found by Ueno et al. in two successive experiments, we have found complete wetting by the ⁴He-rich phase. Our new results have two consequences: first, we suspect that there were some artefacts in the experiments by Ueno et al. Secondly, we now believe that the critical Casimir forces are dominated by the van der Waals force in this experimental situation.     

Reconstructing a textured CAD model of an urban environment using vehicle-borne laser range scanners and line cameras

Abstract. In this paper, a novel method is presented for generating a textured CAD model of an outdoor urban environment using a vehicle-borne sensor system. In data measurement, three single-row laser range scanners and six line cameras are mounted on a measurement vehicle, which has been equipped with a GPS/INS/Odometer-based navigation system. Laser range and line images are measured as the vehicle moves forward. They are synchronized with the navigation system so they can be geo-referenced to a world coordinate system. Generation of the CAD model is conducted in two steps. A geometric model is first generated using the geo-referenced laser range data, where urban features, such as buildings, ground surfaces, and trees are extracted in a hierarchical way. Different urban features are represented using different geometric primitives, such as a planar face, a triangulated irregular network (TIN), and a triangle. The texture of the urban features is generated by projecting and resampling line images onto the geometric model. An outdoor experiment is conducted, and a textured CAD model of a real urban environment is reconstructed in a full automatic mode.     

Structural effect of a series of block copolymers consisting of poly(N-isopropylacrylamide) and poly(N-hydroxyethylacrylamide) on thermoresponsive behavior

Well-defined diblock and triblock copolymers consisting of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-hydroxyethylacrylamide) (PHEAA) were prepared using the atom transfer radical polymerization (ATRP) method. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed. The lower critical solution temperature (LCST) of a series of block copolymers with different compositions was examined using a turbidimetry analysis. The copolymers with a relatively lower molar fraction of HEAA units in the polymer chain exhibited phase transition phenomenon, in which the LCST depended on the fraction in the copolymer. On the other hand, the LCST disappeared for the copolymers with higher HEAA unit molar fractions. The ¹H NMR measurement clarified that the disappearance of the LCST was attributed to the formation of the water-soluble micelle. Furthermore, the thermoresponsive property of the series of block copolymers was elucidated on the basis of the structural effect of the copolymer, which includes the order and length of the block segments.     

Novel strengthening method of closed-cell aluminum foams through surface treatment by resin

Aluminum foams are focused on as a lightweight structural material because of their excellent energy absorbing capacity. However, compressive strength of aluminum foams is much lower than that of dense aluminum. This is due to local buckling of the inhomogeneous cell structure. The authors carried out infiltration of open surface pores with polyester resin because buckling starts at the open surface pores. Compressive tests using commercial aluminum foams show significant increases in compressive strength and absorbed energy. Since the density of resin is not high, the specific compressive strength and specific absorbed energy are also increased.     

Regulation mechanism of the lateral diffusion of band 3 in erythrocyte membranes by the membrane skeleton

Mechanisms that regulate the movement of a membrane spanning protein band 3 in erythrocyte ghosts were investigated at the level of a single or small groups of molecules using single particle tracking with an enhanced time resolution (0.22 ms). Two-thirds of band 3 undergo macroscopic diffusion: a band 3 molecule is temporarily corralled in a mesh of 110 nm in diameter, and hops to an adjacent mesh an average of every 350 ms. The rest (one-third) of band 3 exhibited oscillatory motion similar to that of spectrin, suggesting that these band 3 molecules are bound to spectrin. When the membrane skeletal network was dragged and deformed/translated using optical tweezers, band 3 molecules that were undergoing hop diffusion were displaced toward the same direction as the skeleton. Mild trypsin treatment of ghosts, which cleaves off the cytoplasmic portion of band 3 without affecting spectrin, actin, and protein 4.1, increased the intercompartmental hop rate of band 3 by a factor of 6, whereas it did not change the corral size and the microscopic diffusion rate within a corral. These results indicate that the cytoplasmic portion of band 3 collides with the membrane skeleton, which causes temporal confinement of band 3 inside a mesh of the membrane skeleton.     

Fabrication of a spiral microcoil using a 3D-LIGA process

LIGA processes have been developed generally in the 2.5D world. We introduced techniques of 3D X-ray lithography and worm injection molding with a unscrewing release mechanism, and succeeded in the development to three dimensions of LIGA process. We called this technology 3D-LIGA process, and came to be able to fabricate the plastic molded product with a spiral microstructure. Furthermore, we succeeded in the trial production of a spiral microcoil using 3D-LIGA process and metallization technique combining flat and smooth electroplating with a leveling agent and an isotropic chemical etching. The diameter of this microcoil was 0.5 mm and the length was 1 mm. The width of the Cu coil line was 10 μm, and the pitch was 20 μm. Moreover, we measured characteristics of this microcoil as an inductor. The inductance and the quality factor at the frequency of 1 GHz were 91 nH and 5.8, respectively. This is the first time successful fabrication of an electric device with a 3D form like a spiral microcoil using the 3D-LIGA process has been achieved.     

Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb−Sn solders (melting point (mp) = 573 – 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu−X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu−X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu−X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.