Effects of polyglycerol esters of fatty acids and ethylene‐vinyl acetate co‐polymer on crystallization behavior of biodiesel

Biodiesel fuels (BDF) have many problems in the cold due to their crystallization properties. In particular, precipitation of large crystals of high‐melting fractions in BDF at low temperatures remarkably changes cold flow property of BDF and, thereby, it increases the values of cold filter plugging point. In this study, we evaluated polyglycerol esters of fatty acids (PGE) and ethylene‐vinyl acetate co‐polymer (EVA) as chemical additives to improve the cold flow property of palm oil‐based FAME (PFME). The results of solid fat content measurement indicate that the simultaneous addition of PGE and EVA showed synergistic effects on suppression of crystallization of PFME, however such effect was not observed when EVA was used alone. DSC thermograms indicated that the PGE additives not only decreased the crystallization temperature but also kinetically suppressed the crystal growth. Polarized light microscopy showed that the simultaneous addition of PGE and EVA led to the formation of considerably small and fine‐dispersed crystals of PFME. These results indicate that combined effects of PGE and EVA caused the formation of fine‐dispersed PFME crystals, which could improve the viscous properties of palm oil‐based BDF at relatively cold temperatures.     

Beat Noise Mitigation of Spectral Amplitude Coding OCDMA Using Heterodyne Detection

In order to relax the limitation of the number of multiplexed signal lights caused by beat noise between signal lights, we investigate the applicability of a heterodyne detection technique to a spectral amplitude coding optical code division multiple access scheme. In this investigation, for the first time, we found analytically that the optical frequency chips that form parts of the signal and local lights require uniform phase differences even for envelope detection. We also confirm this requirement and our theoretical analysis experimentally.     

A highly integrated 40-MIPS (peak) 64-b RISC microprocessor

A 1-million transistor 64-b microprocessor has been fabricated using 0.8-μm double-metal CMOS technology. A 40-MIPS (million instructions per second) and 20-MFLOPS (million floating-point operations per second) peak performance at 40 MHz is realized by a self-clocked register file and two translation lookaside buffers (TLBs) with word-line transition detection circuits. The processor contains an integer unit based on the SPARC (scalable processor architecture) RISC (reduced instruction set computer) architecture, a floating-point unit (FPU) which executes IEEE-754 single- and double-precision floating-point operations a 6-KB three-way set-associative physical instruction cache, a 2-KB two-way set-associative physical data cache, a memory management unit that has two TLBs, and a bus control unit with an ECC (error-correcting code) circuit     

One-Dimensional Phonon State of 4He Films Adsorbed in Straight Nanopores

We have studied heat capacities of ⁴He adsorbed in straight nanopores 1.8, 2.2, and 2.8 nm in diameter. Heat capacities of the ⁴He fluid film on the solid layer at 0.08–0.4 K show power laws close to T in 1.8 nm pores, close to T ² in 2.8 nm pores, and a crossover from T to T ² with increasing temperature in 2.2 nm pores. These heat capacities are explained by a model assuming a phonon dispersion with continuous one-dimensional (1D) states in the axial direction and discrete energy levels in the azimuthal direction. By fitting experimental data to the model, the phonon velocity along the pore axis and the energy gap for propagation in the cross section are derived. At temperatures sufficiently lower than the energy gap, where the thermal wave length of phonons is much longer than the effective pore diameter, the ⁴He fluid films show a T-linear heat capacity of 1D phonons propagating only along the pore axis. At higher temperatures, a 1D-2D crossover of phonons occurs.      

Insulation performance of pressurized liquid helium underquench-induced thermal bubble disturbance for superconducting powerapparatus

We have been studying quench-induced `dynamic' breakdown characteristics of LHe and have already found that the electrical insulation performance of LHe was degraded drastically by the thermal bubble disturbance due to quench of superconductors. In this paper, in order to improve the insulation performance of LHe under quench conditions, we measured dynamic breakdown and prebreakdown characteristics of pressurized LHe. Experimental results revealed that breakdown voltage of LHe under quench conditions at 0.2 MPa was greatly improved, reaching 2 to 4× compared with that at atmospheric pressure under both uniform and non-uniform electric fields. Moreover, for practical and efficient insulation design of superconducting power apparatus, we investigated the dynamic breakdown voltage of LHe as functions of pressure and gap length     

The influence of scale/metal interface characteristics on the oxidation behaviour of iron at elevated temperatures

The oxidation kinetics of cold-rolled Remko iron coupons in purified oxygen at atmospheric pressure in the temperature range 973–1173K and the morphologies of both oxide scales and subtrate surfaces were studied using thermogravimetric, metallographic and scanning electron-microscope techniques.Parabolic oxidation rate constants were found to decrease after initial varying periods of constancy, an effect believed to be due to void formation at the wüstite/iron interfaces by the coalescence of vacancies. The observed subsequent recoveries of the values of the rate constants were considered to be due to an increase in oxide growth stresses to values large enough to cause appreciable plastic flow of oxide, thereby decreasing the number of interfacial voids.The extent of the deviations from the initial values of the rate constants decreased as the oxidation temperature was increased and this was considered to be due to the enhanced plasticity of the scale and increased rate of stress generation which favoured the elimination of the interfacial voids.In the temperature range 973–1073K, there were periods in which logarithmic growth relationships were observed, the mechanism being similar to that suggested by Evans, and involving a continuous increase in the number of interfacial voids.     

Crack propagation analysis in civil engineering structures

A system for crack propagation analysis based on the finite element method is shown. The system is easily applied to the investigation of crack propagation behavior due to fatigue in arbitrary structural members of, for example, steel bridges. Moreover, the user can estimate the residual life of the structure with respect to the fatigue-crack. This paper also includes new mesh generation methods for this purpose, and several numerical examples show the efficiency of the mesh generation and the analysis system.     

Interface state generation mechanism in n-MOSFET's

Uniform carrier injection into the channel of n-MOSFETs generates two types of interface states, depending on the oxide electric field: One is linearly proportional to the injected electron density (Type I), while the other shows a half-power dependence (Type II). Charge-pumping measurements in the temperature range of 77K and 263K show that the type I interface states are located in the mid-gap, while the type II interface states are uniformly distributed in wide energy range. Holes generated at the gate/SiO₂ interface or in the oxide are found to be responsible for the type I interface states, while hydrogen or hydrogen compounds diffusing from the interface cause the type II interface states.     

Hydrothermal synthesis of hydroxyapatite whiskers with sharp faceted hexagonal morphology

We report an effective method for the synthesis of hydroxyapatite whiskers with sharp faceted hexagonal shape employing a low temperature (90 °C) hydrothermal route with calcium nitrate tetrahydrate, diammonium phosphate and urea as starting materials. The key parameters of the synthesis process i.e. duration, temperature cycle of the treatment and starting pH value are carefully varied and the end products are investigated using powder X-ray diffraction (XRD), Raman-scattering, infrared spectroscopy (IR), elemental analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), electron diffraction (ED), and high-resolution TEM (HRTEM) in order to find the optimal reaction conditions that lead to the desired hexagonal morphology of HA whiskers. The results demonstrate that gradual and greater increase in solution pH during the hydrothermal process favors large quantity of the single-crystalline hydroxyapatite whiskers with well defined hexagonal morphology.     

Difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing

We examined the difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing. The detection limits were measured by using a magneto-resistive sensor. Comparing the frequency of an applied magnetic field, the detection limit at 50 Hz is deeper than that at 1 kHz. Comparing the sample structure, the detection limit in the multi-layered samples is deeper than that in the continuous samples. These results are likely due to the differences in the skin depth and conductivity of the sample.