Deformation and fracture of α-β brass two-phase bicrystals at 150 K

The deformation up to fracture at 150 K was undertaken on α-β brass two-phase bicrystals. The variation of the slip systems during the proceeding deformation was studied and explained on the basis of incompatible stresses. The normal stress-strain curves were analyzed for various types of bicrystals and the bending that appeared in the specimens when unloaded was explained with respect to the occurrence of the Bauschinger effect in the α phase. Fracture modes other than those observed at room temperature were present. The results, and other minor problems, were discussed.     

Type classification, color estimation, and specific target detection of moving targets on public streets

This paper describes a vision system that recognizes moving targets such as vehicles and pedestrians on public streets. This system can: (1) classify targets {vehicle, pedestrian, others} and, for vehicles, discriminate vehicle types and (2) estimate the main colors of targets. According to the input images to the system, the categories of targets are set as {mule (golf cart for workers), sedan, van, truck, pedestrian (single or plural), and other (such as noise)}. Their colors are set as six color groups {red, orange, yellow; green; blue, light blue; white, silver, gray; dark blue, dark gray, black; dark red, dark orange}. In this experiment, we collected images of targets from 9: 00 a.m. to 5: 00 p.m. on sunny and cloudy days as system training samples. The recognition ratio was 91.1% under the condition that both the recognition results of type and color agreed with the operators judgment. In addition, the system can detect predefined specific targets such as delivery vans, post office vans, and police cars by combining recognition results for type and color. The recognition ratio for specific targets was 92.9%. For the classification and estimation of targets, we employed a statistical linear discrimination method (linear discriminant analysis, LDA) and a nonlinear decision rule (weighted K-nearest neighbor rule, K-NN).Received: 11 March 2004, Accepted: 11 August 2004, Published online: 20 December 2004 Correspondence to: Osamu Hasegawa     

Enhancement in thermoelectric power factor of M/T/N and M/Bi/M/Bi/M (M and N = Cu or Ni) composite devices welded with T = Bi or Bi<Subscript>0.88</Subscript>Sb<Subscript>0.12</Subscript> alloy

The resultant thermoelectric power factors P of M/T/N and M/Bi/M/Bi/M (M and N = Cu or Ni) devices welded with T = Bi or Bi_0.88Sb_0.12 alloy were measured at 298 K and compared with P values calculated as a function of x by treating these devices as an electrical and thermal circuit, where x is the ratio of thickness of Bi or Bi-Sb alloy to the interval between two thermocouples. Consequently, the Seebeck coefficients of M/T/N devices were enhanced significantly in the middle range from x = 0.3 to 0.8, and the observed P values have a local maximum at small x below x = 0.35. The x-dependence of P values of M/T/N devices was found to be explained well by the simple model proposed here when an enhancement factor in and some reduction in thermal conductivity of pure metal were taken into the calculation. As a whole, however, the observed P values of double-layered M/Bi/M/Bi/M devices are lower than those of single-layered M/Bi/M, so that the macroscopic multi-layering of thermoelectric materials has no effect on the enhancement in P. The maximum P (= 22.1 mW/K²m) of Cu/Bi-Sb/Cu is 1.5 times larger than that of Cu/Bi/Cu and reached 3.6 times as large as the mean value of 5.7 and 6.6 mW/K²m of the high-performance bulk p- and n-type bismuth-telluride compounds.     

High-performance genetic analysis on microfabricated capillary array electrophoresis plastic chips fabricated by injection molding

We have developed a novel technique for mass production of microfabricated capillary array electrophoresis (mu-CAE) plastic chips for high-speed, high-throughput genetic analysis. The mu-CAE chips, containing 10 individual separation channels of 50-microm width, 50-microm depth, and a 100-microm lane-to-lane spacing at the detection region and a sacrificial channel network, were fabricated on a poly(methyl methacrylate) substrate by injection molding and then bonded manually using a pressure-sensitive sealing tape within several seconds at room temperature. The conditions for injection molding and bonding were carefully characterized to yield mu-CAE chips with well-defined channel and injection structures. A CCD camera equipped with an image intensifier was used to monitor simultaneously the separation in a 10-channel array with laser-induced fluorescence detection. High-performance electrophoretic separations of phiX174 HaeIII DNA restriction fragments and PCR products related to the human beta-globin gene and SP-B gene (the surfactant protein B) have been demonstrated on mu-CAE plastic chips using a methylcellulose sieving matrix in individual channels. The current work demonstrated greatly simplified the fabrication process as well as a detection scheme for mu-CAE chips and will bring the low-cost mass production and application of mu-CAE plastic chips for genetic analysis.     

Development of a frequency-detuned interferometer as a prototype experiment for next-generation gravitational-wave detectors

We report on our prototype experiment that uses a 4-m detuned resonant sideband extraction interferometer with suspended mirrors, which has almost the same configuration as the next-generation, gravitational-wave detectors. We have developed a new control scheme and have succeeded in the operation of such an interferometer with suspended mirrors for the first time ever as far as we know. We believe that this is the first such instrument that can see the radiation pressure signal enhancement, which can improve the sensitivity of next-generation gravitational-wave detectors.     

Dynamic observation of vortices in superconductors using a holography electron microscope

Individual vortices in superconductors are directly observed with our holography electron microscope. Vortices cannot be viewed as an electron micrograph, but only as a holographic interference micrograph or a defocused micrograph (Lorentz micrograph), since vortices are phase objects to the illumination electron beam. Since the flux itself, and not its replica, is detected, even the dynamic behavior can be observed. The dynamics of vortices in a Nb thin film can be observed in real time when the sample conditions, such as the temperature or the applied magnetic field, change.