Simulation for 3-D optical and electrical analysis of CCD

A device simulator, SPECTRA, and an optics simulator, TOCCATA, were developed for three-dimensional (3-D) optical and electrical analysis of a charge-coupled device (CCD). SPECTRA solves Poisson's and time dependent current continuity equations by a novel Gummel's method. Since the basic parameters are potential and exponential functions of the quasi-Fermi level of electrons and holes, the solution can be obtained in a stable and rapid way compared to the conventional method. TOCCATA calculates the shape of layers, which consist of silicon-oxide, silicon-nitride, poly-silicon, light shield metal, micro-lens material, etc., formed on a silicon substrate and performs ray tracing on multiple reflection, refraction, and absorption or executes wave analysis which involves interference and diffraction. The combination of these simulators realizes the optical and electrical analysis for the total design of CCD cell structures on and in a silicon substrate. It is reported that the simulation method successfully analyzes the optical and electrical characteristics of interline-transfer charge-coupled devices (IT-CCD)     

Tripless control method for general-purpose inverters

The control method described prevents general-purpose inverters without current regulators from tripping easily, i.e. to be tripless no matter how their load is varied, and enables motors to rotate stably at high frequencies. It uses only current sensors and is a combination of pulse-width-modulated (PWM) control and torque control. The PWM control changes an asynchronized mode to a synchronized mode when the modulation ratio becomes more than one, enabling the carrier wave frequency to be continuously varied with the inverter frequency so that motors can rotate stably over a wide frequency range. The torque control uses a real and reactive component detector, magnetic flux compensator, slip compensator, and current limit controller. Experiments prove that this tripless control can be satisfactorily applied to general-purpose inverters     

Development of DNA markers for discrimination between domestic and imported beef

In the meat industry, correct breed information in food labeling is required to assure meat quality. Genetic markers provide corroborating evidence to identify breed. This paper describes the development of DNA markers to discriminate between Japanese and Australian beef. Two Bos indicus-specific markers and MC1R marker were used as possible candidate markers. Amplified fragment length polymorphism method was employed to develop additional candidate markers. The 1564 primer combinations provided three markers that were converted into single nucleotide polymorphisms markers for high-throughput genotyping. In these markers, the allele frequencies in cattle from both countries were investigated for discrimination ability using PCR-RFLP. The probability of identifying Australian beef was 0.933 and probability of misjudgment was 0.017 using six selected markers. These markers could be useful for discriminating between Japanese and Australian beef and would contribute to the prevention of falsified breed labeling of meat.     

Effects of Mn content and texture on fatigue properties of as-cast and extruded AZ61 magnesium alloys

Fatigue behavior of as-cast and extruded AZ61 magnesium alloys in ambient air (20 °C–55%RH) was investigated. It was found that size and distribution of cast defect influenced tensile and fatigue performance of the as-cast alloy. Fatigue limit of the as-cast alloy was significantly low compared to the extruded alloy. The casting defects served as stress concentration sites for fatigue crack nucleation. Fatigue tests were also carried out on a high Mn content alloy. All of the specimens failed from an inclusion near the specimen surface. Fatigue limit of Mg alloy with high Mn content was lower compared to that of the low Mn content alloy. Further, investigation on the effect of texture on fatigue and fatigue crack growth behavior of the extruded AZ61 magnesium alloy plate was carried out. The results showed that fatigue strength in the longitudinal direction to the extruded direction was higher compared to those in the transverse and 45° directions. Significant effect of specimen orientation on fatigue crack growth behavior for both short and long cracks was found near the threshold region. However, regardless of specimen orientation, the da/dN–ΔK_eff curves for all three kinds of specimens were in a narrow band. It is suggested that the difference in the fatigue life among the specimen orientations will be mainly due to the difference in the crack closure behavior. A transition of fracture mechanism was found for a long crack. Slip fracture mechanism was dominant above the transition point, whereas below the transition point, slip fracture mechanism was associated with cleavage fracture.     

Fatigue crack growth behavior of silica particulate reinforced epoxy resin composite

In the present work, fatigue crack growth tests of epoxy resin composite reinforced with silica particle under various R-ratios were carried out to investigate the effect of R-ratio on crack growth behavior and to discuss fatigue crack growth mechanism. Crack growth curves arranged by ΔK showed clear R-ratio dependence even under no crack closure, where the values of ΔK_th were 0.82 and 0.33 MPa √m for R = 0.1 and 0.7 respectively. However, crack growth curves arranged by K_max merged into almost one curve regardless of R-ratio, which indicated that crack growth behavior of the present composite was time-dependent. The value of K_max,th were in the range from 0.78 to 1.12 MPa √m. In situ crack growth observation revealed the crack growth mechanism: micro-cracking near the interface between silica particle and resin matrix occurs ahead of a main crack and then micro-cracks coalesce with a main crack to grow. The crack path was in the epoxy matrix, which was consistent with the time-dependent crack growth.     

On‐Demand Control of the Photochromic Properties of Naphthopyrans

Photofunctional compounds have emerged as critically important materials for both fundamental studies and industrial applications. Control of the thermal decoloration speed to within several seconds while sustaining satisfactory photochromic colorability is an important challenge for the application of such materials to photochromic lenses and smart windows. Photochromic naphthopyran derivatives are utilized for photochromic lenses because of their high durability and easily controllable colorability. However, the residual color imparted by the long‐lived transient species upon ceasing light irradiation remains a hindrance to practical applications. In this study, a strategy is demonstrated for on‐demand control of the thermal decoloration speed of the transient colored species of naphthopyran derivatives. The increase in the ring‐size of the alkylenedioxy moiety on the naphthopyrans accelerates the thermal back‐reaction independently of the maximum‐absorption wavelength of the colored isomer, leading to the realization of yellow‐, red‐, and blue‐photochromic naphthopyrans with similar thermal fading speeds. This novel molecular design provides a strategy for the future development of advanced photoresponsive materials.     

Measurement of telescope aberrations through atmospheric turbulence by use of phase diversity

We conduct computer simulations of the reconstruction of a wave front at a telescope pupil with the phase-diversity method. An instantaneous wave front is reconstructed from focused and defocused specklegrams of a point star. In the wave-front reconstruction we do not fit the wave front to Zernike polynomials but retrieve the phase with a phase-unwrapping procedure. Averaging over many atmospherically perturbed wave fronts leads to the residual phase error, namely, the aberration of the telescope. The scintillation effect, nonuniformity of amplitude on a telescope pupil, is also discussed.