Fast Calculation of Computer-Generated Fresnel Hologram Utilizing Distributed Parallel Processing and Array Operation

Fresnel CGH for a three-dimensional (3-D) object is generated by calculating the Fresnel diffraction, but it requires a huge amount of calculation. This is one reason for the difficulty in realizing real-time holography. We propose fast calculation method of computer-generated Fresnel hologram (Fresnel CGH) utilizing distributed parallel processing and array operation. In our method, a projected image with depth information of the 3-D object is prepared to calculate the Fresnel diffraction. The Fresnel diffraction of the projected image is then calculated with depth information by array operation and distributed parallel processing. Parallel processing is realized using JavaSpaces and many standard computers. In our array operation, calculation error in phase distribution on a hologram occurs more than the strict Fresnel diffraction. However, it was confirmed by experiments that the influence of an error can be controlled and ignored. In this paper, our proposed method and some experimental results are shown.     

Selective determination of cadmium(II) from divalent metal ions in environmental samples by capillary electrophoresis using in-capillary complexation with a lacunary Keggin-type [PW11O39]7- complex.

A novel capillary electrophoretic (CE) method, based on in-capillary complexation with [PW(11)O(39)](7-), was developed for the determination of cadmium(II) in natural water samples. When a sample solution is injected into a capillary containing 0.20 mM [PW(11)O(39)](7-) and 0.10 M malonate buffer (pH 3.0), the ternary Keggin-type complex, [P(Cd(II)W(11))O(39)](5-), which possesses high molar absorbtivities in the UV region, is formed in the capillary, and its migration toward the anode gives a well-defined migration peak in the electropherogram. An advantage of this method is that many divalent metal ions do not interfere. The proposed method was successfully applied to the determination of Cd(II) in environmental samples. The detection limits were 1 x 10(-7) and 5 x 10(-7) M for river-water and seawater samples, respectively (signal-to-noise ratio = 3).     

A new class of 30-molybdo complexes: Formation,structure and electrochemical properties of bisselenitopyrophosphatotriacontamolybdate, [(SeO3)2(P2O7)Mo30O90]8−, and bispyrophosphatotriacontamolybdate, [(P2O7)2Mo30O90]8−

The tetrapropylammonium (Pr₄N⁺) salt of [(SeO₃)₂(P₂O₇)Mo₃₀O₉₀]^8? was prepared from a 75 mM Mo^VI–2.8 mM P₂O₇^4?–5.6 mM SeO₃^2?–0.95 M HCl–60% (v/v) CH₃CN system, where [(P₂O₇)Mo₁₈O₅₄]^4? and [H₆(SeO₃)₂Mo₁₅O₄₈]^4? are first formed, then being spontaneously fused into [(SeO₃)₂(P₂O₇)Mo₃₀O₉₀]^8?. The [(SeO₃)₂(P₂O₇)Mo₃₀O₉₀]^8? anion may be isotypic with [(HPO₃)₂(P₂O₇)Mo₃₀O₉₀]^8?, in which each side of a (P₂O₇)Mo₁₂O₄₂ fragment is capped by a B-type (HPO₃)Mo₉O₂₄ unit derived from [H₆(HPO₃)₂Mo₁₅O₄₈]^4?. [(XO₃)₂(P₂O₇)Mo₃₀O₉₀]^8? (X = HP, Se) have the same type of 30-molybdo framework as [(P₂O₇)₂Mo₃₀O₉₀]^8?, previously isolated by Koltz. These three 30-molybdo complexes with the same ionic charge of ?8 constitute a new class of polyoxometallates and have common properties of undergoing a two-electron reduction in the absence of H⁺.     

Optical heterodyne measurement of in-plane vibrations

An optical heterodyne technique which detects the frequency shift of light reflected from a point in motion can be successfully used for in-plane vibration measurements. Principles and results of preliminary experiments are described.     

Ultrasonic imaging using air-coupled P(VDF/TrFE) transducers at 2 MHz

A reflection non-contact ultrasonic microscope system working both in amplitude and phase difference modes at 2 MHz has been developed using an air-coupled concave transducer made of piezoelectric polymer films of poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]. The transducer is composed of three 95 μm-thick P(VDF/TrFE) films stacked together, each of which is activated electrically in parallel by a driving source. The transducer has a wide aperture angle of 140° and a focal length of 10 mm. The measured two-way transducer insertion loss is 80 dB at 1.83 MHz. Despite 20 dB higher insertion loss than that estimated from Mason’s equivalent circuit, we have obtained clear amplitude acoustic images of a coin with transverse resolution of 150 μm, and clear phase difference acoustic images of the rough surface of a paper currency bill with depth resolution of sub-micrometer. Using two planar transducers of P(VDF/TrFE), we have also successfully measured in through-transmission mode the sound velocity and absorption of a 3 mm-thick silicone-rubber plate. The present study proves that, owing to its low acoustic impedance and flexibility, P(VDF/TrFE) piezoelectric film is very useful for high frequency acoustic imaging in air in the MHz range.     

A miniature ultransonic pump using a bending disk transducer and a gap

It is known that if a pipe end is faced at a vibrating surface in liquid with a small gap, liquid is suctioned into the pipe. As a miniature configuration, we introduce a bending disk transducer 30 mm in diameter using a ring-shaped PZT element. The disk vibrator is worked at the fundamental resonance frequency of 19 kHz of the bending mode. To optimize the pipe geometry, we experimentally investigated the effect of the outer diameter on the pump performance. As a result, the outer/inner diameter ratio of 3:2 is optimum for the gap smaller than 20 microm. We achieved the maximum pump pressure of 14.8 kPa and the maximum flow rate of 10 ml/min. using the prototype pump.     

Holding characteristics of planar objects suspended by near-field acoustic levitation

The authors have found the acoustic levitation phenomenon where planar objects of 10 kg weight can be levitated near a vibration surface. This phenomenon has been studied for non-contact transportation. A circular planar object can be suspended without contacting a circular vibration plate. We have studied the holding force which acts horizontally on the levitated objects. The horizontal position of the object is stabilized by this force. In this paper, we discuss the effect of the radius of a levitated object, levitation distance, displacement amplitude of the vibration plate and the vibration mode on the suspending force.     

Structure Development via Reaction-Induced Phase Separation in Polymer Mixtures: Analysis of Early- and Late-Stage Demixing and Computer Simulations at Non-Isoquench Depths

The effects of phase separation during polymerization of a monomer/polymer mixture were studied. The kinetics of the spinodal decomposition of glycidyl phenyl ether/polystyrene (95/5) during polymerization was investigated using a light-scattering technique. This phase separation during polymerization was comparatively different from the one observed at the isoquench depth such that (i) there was significantly more time before any observable fluctuation, and (ii) the periodic distance of the resulting two-phase structure in the later stages decreased with time. To further investigate the influence of a continually increasing quench depth on phase separation, a diglycidyl aminophenol/diglycidyl ether of bisphenol A (50/50) system with a simple phase diagram was investigated using ultra-small-angle X-ray scattering analysis, and a similar phase separation behavior was observed. Furthermore, computer simulations using the dynamic self-consistent field method were performed to interpret polymer morphology during the demixing driven by chemical reactions. The simulation results suggested that the periodic distance of the resulting two-phase structure formed in the later stages decreases with time. The time dependence of the concentration fluctuations observed in these simulations provided a satisfying explanation for the morphologies formed as a result of a continuously increasing quench depth.     

Ti(NMe2)4-catalyzed Markovnikov hydroamination of alkynes in the presence of N-heterocyclic carbenes and LiN(SiMe3)2

Intermolecular hydroamination of alkynes catalyzed by Ti(NMe₂)₄ was much improved with N-heterocyclic carbenes and LiN(SiMe₃)₂, by which high Markovnikov selectivity was attained for the coupling of nearly all alkynes and amines.