High-speed optical Fourier transformer

A new type of high-speed signal processing or analyzing device-the picosecond Fourier transformer-is proposed. The device can be used to obtain the Fourier transform of the time-dependent intensity of an optical signal. The device makes use of the spatially distributed electrooptic modulator or deflector, and has the potential for terahertz bandwidth and picosecond time resolution. Practical devices are considered and their performances (bandwidth, frequency resolution, etc.) are discussed. The operation of the proposed device is demonstrated in the microsecond range by a preliminary experiment using LiTaO3e-o deflectors.     

Moisture migration and drying properties of hardened cement paste and mortar

The moisture migration and drying properties of hardened cement paste and mortar are studied experimentally and analytically. Thin-wall cylindrical specimens with a thickness of about 1.0 mm are used to reduce hygral gradients. The specimens are loaded with different compressive stresses in the range 0–11 MPa. Two test series are perfirmed: loss of water (test 1) and migration of moisture through the thin wall of the specimens (test 2) are measured: Furthermore, the experimental results are analyzed as a non-linear diffusion process, by means of the finite element method. The effects of the compressive stress and aggregates are discussed, referring to the diffusion coeffients obtained.     

An MPPT control scheme for a PV system utilizing limit cycle operation and its system design

This paper proposes a new simple maximum power point tracking (MPPT) control scheme for a PV system without using conventional “mountain climbing” optimum operating point searching technique. Although no information is needed on PV array, the generated output power is maximized by utilizing limit cycle phenomena occurring on the equilibrium/nonequilibrium boundary of system power flow. A parameter design procedure to determine operating period based on a theoretical model is presented. It has been found that the operating period of limit cycle is kept constant depending on the circuit and control parameters irrespective of the insolation conditions of PV array. Availability of the proposed new MPPT control scheme has been shown by simulation and experimental results. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(2): 67–75, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10134     

Coronary artery bypass graft surgery in dialysis patient

To determine the operative outcome of coronary artery bypass graft surgery (CABG) for severe coronary artery disease in long-term hemodialysis patients, we analyzed a group of 16 patients who underwent CABG over a ten-year period in our institution. Hospital mortality was 12.5% (2 of 16 patients). These two patients died of ischemic colitis and perioperative myocardial infarction, respectively. There were five late deaths: one patient died from myocardial infarction, one from uremia, one from gastro-intestinal bleeding, one from gastric cancer and one from unknown cause. There were four significant postoperative complications (morbidity 25%), consisted of one pulmonary tuberculosis, one sternal dehiscence secondary to mediastinitis, one mediastinal hematoma secondary to late bleeding from the LITA dissection area and one A-V shunt trouble. Graft patency rate within the first two months was 93% (30 to 42 in 13 patients). Hospital survivors experienced complete relief from angina. Actuarial survival was 68.8% at 3 years, 57.3% at 5 years and 28.6% at 7 years. This rate is not significantly different from the survival of all dialysis patients, but seems to be better than that of dialysis patients with not operated coronary artery disease. We concluded that CABG in dialysis patients can be accomplished with acceptable morbidity and mortality and effective relief of symptoms.     

Construction of Chemical Potential Diagrams for Metal-Metal-Nonmetal Systems: Applications to the Decomposition of Double Oxides

A chemical potential diagram for A-B-O (A, B = metallic elements) systems has been constructed to make visually clear the thermodynamic stability of double oxides; the stability area of metallic elements, their binary oxides, and double oxides can be presented as convex polygons in a log ( a _A/ a _B) vs log P (O₂) plot, a and P (O₂) being the activity of metallic elements and the oxygen partial pressure, respectively; the axis variable, log ( a _A/ a _B), is used to treat two metallic elements equivalently. The Co-Ti-O and La-Co-O systems have been chosen as examples to demonstrate how the present diagram can provide complicated phase relations in a compact and visualized manner. An attempt has also been made to utilize this diagram to present graphically products of kinetic decomposition of double oxides placed in an oxygen potential gradient.     

A proposed method for the polarographic determination of Mo(IV) in the presence of glycolic,lactic or malic acid

It was found that the polarographic reduction of molybdate(VI) was possible in the presence of glycolic, lactic and malic acids in neutral borate-phosphate solution. The polarographic wave was precisely proportional to the concentration (<10^?2M) of molybdate, and hence the straight line was useful as a calibration curve in quantitative analysis of molybdate. It was suggested that a reducible species on a mercury electrode was molybdate complex produced through hydrogen (glycolic, lactic or malic acid)-oxygen (molybdate) bond.     

Frictional properties of monomolecular layers of silane compounds

The frictional performance of ultrathin films was evaluated, especially in monomolecular layers of silane compounds. The monolayer of γ-(N,N- dioctadecylsuccinylamino)propyltriethoxysilane is one of the candidates for the best lubricating film. The film exhibited a low coefficient of kinetic friction, μ_k < 0.1, and 10⁵ transits without stick-slip. From X-ray photoelectron spectroscopy and Fourier transform IR analysis, both the adhesion between the molecules of the lubricant and the surface of the substrate and the cohesion between the molecules of the lubricant are extremely strong.     

On bang-bang solutions of stochastic differential games

We consider two classes of scalar stochastic differential games with hard constraints on controls. The solutions are found to be bang-bang, by extending a technique developed earlier for stochastic optimal control problems.