Ascorbic acid enrichment of whole potato tuber by vacuum-impregnation

The aim of this study was to evaluate the use of vacuum-impregnation (VI) for enriching the ascorbic acid content of whole potatoes. Whole potatoes were immersed in a 10% ascorbic acid (AA) solution. A vacuum pressure of 70 cm Hg was applied for 0–60 min, following atmospheric pressure restoration for 3 h, while samples remained in the VI solution. AA concentrations of potatoes were measured using HPLC. The effects of cooking and storage time in subsets of the fortified samples were also evaluated. Results indicated that the AA concentration of whole potatoes increased with vacuum time (max 150 mg/100 g fr. wt.). In addition, a steam-cooking study showed that 100 g of the 25 min steam-cooked VI potatoes could provide adults with 90–100% of the recommended daily allowance of AA (100 mg). The storage study showed that VI whole potatoes had a relatively high AA concentration (50 mg/100 g fr. wt.), even at 14 days of storage at 4 °C. This study indicated that VI treatment of whole potatoes was useful for enriching the AA content.     

Distributed against centralised crossbar function for realising bank-based multiport memories

The two extreme functionally equivalent possibilities of distributed or centralised crossbar function for realising a bank-based multiport memory are compared on the basis of required global signal and transistor numbers. With respect to both measures, the distributed crossbar function is found to be the better choice for practically relevant multiport-memory configurations.     

High Power Characterization of Piezoelectric Materials

Three techniques for measuring high voltage/power piezoelectric properties, which have been developed recently, are compared: a voltage-constant piezoelectric resonance method, a current-constant piezoelectric resonance method, and a pulse drive method. The conventional resonance method with a constant voltage circuit exhibits significant distortion (or a hysteresis) in the resonance frequency spectrum under a high vibration level due to large elastic non-linearity, which limits precise determination of the electromechanical coupling parameters. To the contrary, the resonance method with a constant current circuit (i.e., constant velocity) can determine the coupling parameters more precisely from a perfectly-symmetrical resonance spectrum. The general problem in both resonance methods is heat generation in the sample during the measurement. In order to separate the temperature characteristic from the non-linearity, it is recommended that the pulse method be used in parallel, even though the accuracy is not very high.     

An ultrasonic motor driven by the phase-velocity difference between two traveling waves

This paper presents a new ultrasonic motor in which the rotor rotation speed is locked by the phase-velocity difference between the two traveling waves propagating on the stator and the rotor. First, the unique construction to excite two traveling waves both in the stator and the rotor is described. Then, the operation principle of the present motor is revealed by our careful experiments. Dynamics of the two traveling waves are measured by an in-plane laser Doppler vibrometer under various conditions, as well as the motor performances. Our experiments show that the rotation speed of the motor is equal to the phase-velocity difference between the two traveling waves on the contact surfaces of rotor and stator. It is confirmed that the rotor rotates so as to cancel the phase-velocity difference between the traveling vibrations along the circumferences of the rotor and stator. If the load does not exceed the maximum torque that is determined by the vibration amplitude, the rotation speed is subject only to the phase-velocity difference.     

Left ventricular function during dynamic exercise in untrained and moderately trained subjects

The influence of exercise training on left ventricular function at rest (R), at anaerobic threshold (AT), and during peak exercise (PE) was evaluated in 12 healthy untrained and 13 trained (T) subjects who underwent Doppler echocardiography at R and radionuclide ventriculography at R and during exercise. The end-diastolic volume and stroke volume were significantly higher in the T group than in the untrained group at R. The ejection fraction rose significantly from R to AT and from AT to PE (80.0 +/- 0.84 vs. 83.6 +/- 0.91%), but no significant difference was observed between groups. The peak diastolic filling rate rose significantly during exercise, with a further significant increase observed in the T group (AT, 6.38 +/- 0.40 vs. 5.01 +/- 0.16 end-diastolic counts/s; PE, 8.24 +/- 0.42 vs. 7.15 +/- 0.35 end-diastolic counts/s). The percent variation of minimal systolic counts fell significantly at AT and PE in relation to R. Our data demonstrate that exercise training produces a significant increase in peak diastolic filling rate but no change in systolic function during exercise and that metabolic acidosis caused by exercise does not limit systolic function.     

Morphological study of the wear of crystalline polymers II: Isotactic poly(propylene)

The morphology of the worn surface and wear debris of isotactic poly(propylene) (PP) slid against steel in air and water was studied. From electron micrographs, electron diffraction patterns and X-ray diffraction patterns it was found that both the worn surface and the wear debris had a smectic structure. Plastic deformation of the surface of PP took place during frictional contact both in air and in water, giving rise to the formation of thick meandered fibrous aggregates with their longitudinal axes nearly perpendicular to the sliding direction and thin fibrils aligned parallel to the sliding direction.     

Stability of PZT Piezoelectric Ceramics under Vibration Level Change

Stability of the piezoelectric properties with changing vibration level was studied in lead zirconate–titanate (PZT) ceramics by using the constant-current/velocity driving method. The changes of Young's modulus Y^E₀ and mechanical loss factor Q^–1_m are a function of the square of effective vibration velocity v ₀. The nonlinear proportional constants of the above functions indicate the degree of stability under vibration level change. The stability of PZT estimated by these constants coincides with the results obtained through the heat generation study.     

Insulation characteristics of GIS under nonstandard lightning‐impulse oscillations: Insulation characteristics under single‐frequency oscillations with various frequencies and damping ratios

To improve GIS insulation specifications, it is important to recognize the insulation characteristics under oscillatory overvoltage waveforms occurring in the field. This paper describes investigations of insulation characteristics for single‐frequency oscillatory waveforms with various frequencies and damping ratios. It was found that minimum breakdown voltages (V_min) rose with frequency rising under the same damping condition and V_min rose with damping ratio rising under the same frequency condition. From an analysis of actual breakdown voltage characteristics, the probability of breakdown at a valley of oscillation rose with damping increasing. It was found that the insulation characteristics were treated all‐inclusively based on the characteristics of V_min for rise time or damping time. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(3): 43–49, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10156     

The effect of pelleting of alfalfa hay on methane production and digestibility by steers

A modified 2 × 2 factorial experiment with 19 steers was used to study methane (CH₄), CO₂ and heat production and O₂ utilization and the energy digestibility of pelleted and chopped first- and second-cut alfalfa at maintenance and 1.6 times maintenance in steers. Methane production, dry matter digestibility and urinary energy loss were reduced (P < 0.05) when first-cut alfalfa was pelleted but pelleting had no influence on these parameters with second-cut alfalfa. Methane and CO₂ production and O₂ utilization increased sharply after feeding. There were interactions between type of feed (chopped vs. pelleted) and cut of alfalfa in CH₄ (1 kg⁻¹ feed DM) and CO₂ production and O₂ utilization. Energy digestibility and CH₄ losses were similar at maintenance and 1.6 times maintenance level of feeding. Although methane production was lower in cattle fed pellets in three out of four comparisons of pelleted and chopped hay diets, the decline in energy loss as CH₄ due to pelleting was not sufficient to justify the extra energy expended to pellet diets from an environmental or economic point of view.     

具有反射率及亮度补偿功能的光纤振动计

介绍了一种结构简单、价格低、带有反射率和亮度补偿的光纤振动计。该光纤式振动计由发光二极管、光纤探头和两个光子探测器组成。光纤探头的光纤束分为三部分：一根发射光纤、第一邻近接收光纤组（组A）、第二邻近接收光纤组（组B）。光纤组A和光纤组B的输出信号平均值的比值取决于光纤探头和被测表面之间的平均距离，而与被测表面的反射率及亮度无关。根据这一比值可以实现探头与被测表面间距离的估计。然后根据光纤组A和B的标定曲线，对振动计的灵敏度进行了补偿。因为在比值运算中使用的是平均值，所以振动频率的提高不会限制这一技术的使用。实验结果表明，这一方法适宜于动态测量，可以实现被测表面反射率、入射亮度及探头与被测表面间平均距离的补偿。