Computation of mean-semivariance efficient sets by the Critical Line Algorithm

The general mean-semivariance portfolio optimization problem seeks to determine the efficient frontier by solving a parametric non-quadratic programming problem. In this paper it is shown how to transform this problem into a general mean-variance optimization problem, hence the Critical Line Algorithm is applicable. This paper also discusses how to implement the critical line algorithm to save storage and reduce execution time.     

X-ray absorption spectral analysis with a 9 V battery X-ray generator.

X-ray absorption spectral (XAS) analysis is performed with a combination of a 9 V dry electric battery X-ray generator and a portable Si PIN X-ray detector. The calcium K edge (4.0 keV) in paper is measured with a grazing incidence geometry, which suppressed the artifact due to the Kalpha X-ray fluorescence peak at 3.5 keV. The 9 V dry battery X-ray emitter is useful for portable XAS measurements.     

A four-wavelength channel absorbance detector with a light emitting diode-fiber optics assembly for simplifying the flow-injection analysis system.

A four-channel absorbance detector was developed for simplifying the flow-injection analysis (FIA). This detector used four light-emitting-diodes (LEDs) as light sources; their wavelengths were 470, 495, 590 and 635 nm, respectively. Their amplitudes were modulated electronically with different frequencies. The light emissions from them were merged by plastic-core fiber optics, and were detected by a photo-diode (PD). The mixed signal was then sent to and discriminated by a four-channel lock-in amplifier corresponding to each modulation frequency. Neither a monochromator nor an optical filter was used. This detector was conveniently applied to the determination of iron in river water by FIA using 1,10-phenanthroline. Though a noisy peristaltic pump was used to propel the solutions, practical precision and accuracy were obtained by means of on-line dual-wavelength measurements and off-line moving average calculations.     

Full recoil analysis of the elastic scattering of 16O on 19F by the core-exchange model

An analysis of the scattering ¹⁶O-¹⁹F measured at the energies E_lab = 21.4, 25.8 and 32.0 MeV has been carried out by using the core-exchange model. The value of cfp 〈¹⁹F|}¹⁶O, triton〉 obtained in the present analysis is consistent with that obtained from the analysis of ¹⁹F (³He, ⁶Li)¹⁶O when the recoil effects are included.     

Facile synthesis of thiacalix[n]arenes (n=4, 6, and 8) consisting of p-tert-butylphenol and methylene/sulfide alternating linkage and metal-binding property of the n=4 homologue

2,14-Dithiacalix[4]arene 3₄ was conveniently prepared in 16% yield by acid-catalyzed cyclocondensation of 2,2^′-thiobis[4-tert-butylphenol] with formaldehyde. The present method also afforded the first isolation of the analogues with six and eight phenol units, 3₆ (10%) and 3₈ (5%), respectively. Solvent extraction showed that 3₄ had high selectivity toward Cu²⁺ ion at pH 5.5 by coordination of the bridging sulfur with cooperative donation of the adjacent phenolate oxygens.     

Dynamic responses of electrorheological fluid in steady pressure flow

The dynamic responses of the electrorheological fluid in steady pressure flow to stepwise electric fields are investigated experimentally. First of all, the transient responses of the ER fluid under various electric field strengths and flow velocities are obtained from the pressure behaviors in the flow channel with two parallel-plate electrodes. The response times are exponentially decreased with the increase of the flow velocity and the decrease of the electric field strength. Next, the relationship between the dynamic pressure behaviors of the ER fluid and the cluster structure formation processes of the ER particles is investigated using the flow visualization technique. Through the comparison study, it is verified that the dynamic responses of the ER fluid in the flow mode are mainly caused by the cluster densification process in the competition of the electric field-induced particle attraction and the hydrodynamic force, unlike those in the shear mode determined by the particle aggregation process.