Dielectric and Piezoelectric Properties of Pb(Co1/3Nb2/3)O3-PbTiO3-PbZrO3 Solid Solution Ceramics

Ceramic and piezoelectric properties of the Pb(Co_1/3Nb_2/3)O₃-PbTiO₃-PbZrO₃ system were investigated. The system contains rhombohedral, tetragonal, and pseudocubic phases at room temperature. The triple point is at 0.07Pb(Co_1/3Nb_2/3)O₃-0.43PbTiO₃-0.50PbZrO₃. High dielectric constants (750 to 1500) and radial coupling coefficients (40 to 45%) and low average temperature coefficients of resonant frequency (of the order of 10^-6°C) were obtained for compositions near the morphotropic phase boundary.     

Low‐Voltage‐Ride‐Through Performance of an HVDC Transmission System Using Two Modular Multilevel Double‐Star Chopper‐Cells Converters

This paper presents an intensive discussion on a long‐distance high‐voltage direct‐current (HVDC) transmission system that combines two modular multilevel cascade converters based on double‐star chopper cells (MMCC‐DSCC) with DC power cables. Hereinafter, a single MMCC‐DSCC is referred to as a DSCC converter or just as a DSCC for the sake of simplicity. The HVDC transmission system is required to provide low‐voltage‐ride‐through (LVRT) capability to enhance transmission system availability. This paper proposes a new LVRT method without any direct information exchange between the two DSCC converters. The validity of the method is verified, using simulated waveforms from the software package of “PSCAD/EMTDC” and experimental waveforms from a three‐phase 200‐V, 400‐Vdc, 10‐kW, 50‐Hz downscaled HVDC system with a set of 300‐meter‐long DC power cables.     

Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Acid urease derived from Lactobacillus fermentum was applied to reduce ethyl cthe target level (90 μg/L). However, complete prearbamate (EC) formation in California sherry production. Commercial sherry and sherry base were treated with urease under different conditions. Amounts of urea were determined and EC amounts were monitored by gas chromatography. Urea removal by acid urease reduced EC formation during the baking process and effectively maintained EC concentrations below vention of EC was not achieved because of precursors other than urea.     

病人搬移设备的机电一体化设计和应用

针对在医院里多数采用人工方法搬移受伤、瘫痪或手术前后病人的状况,提出一种新型的病人搬移设备,介绍了病人搬移设备的机电一体化设计和应用。应用这种设备,护士能独自把病人从病床搬移到担架车上或从担架车搬移到病床上而不改变病人的姿态,减轻了护士的劳动强度, 增加了病人的安全感和舒适度。介绍该设备的开发理念、机械设计和控制系统。基于开发理念,采用了模块化机械结构和嵌入式控制系统的机电一体化设计思想。整体机构由四个模块组成,每个模块又包括上、下两部分皮带驱动单元,共有八个电机驱动。所有控制系统全部安装在设备内部,使得搬移设备和担架车相互独立。提出整体设计和机构组成的方法,并对关键部件进行了计算。设计开发了一种用于该设备的嵌入式新型伺服系统,提出其控制原理和控制算法。同步控制试验和在医院的临床应用试验表明该系统是安全有效的。     

Thermostable Proteinase in Salted Anchovy Muscle

Salted anchovy fillets produced in Japan were severely degraded above 35°C and were solubilized completely in a few hours at 55°C. In contrast, raw anchovy fillets were not solubilized, but the solubility of fillets gradually increased during the salting process. In contrast, salted and raw anchovy fillets from southern Europe were relatively stable. Proteolytic activity that digested myosin heavy chain in vitro was found in muscle extracts from both types of salted fillets. Enzymes with activity were high-temperature-active serine proteinases with substrate specificities similar to trypsin. Optimal pH was 7.4 (Japan) and >8.5 (Europe). Neither enzyme showed collagen-degrading activity.     

A Low‐Speed,High‐Torque Motor Drive Using a Modular Multilevel Cascade Converter Based on Triple‐Star Bridge Cells (MMCC‐TSBC)

This paper provides an experiment‐based discussion on a modular multilevel cascade converter based on triple‐star bridge cells (MMCC‐TSBC) for a low‐speed high‐torque motor drive. The TSBC is a direct ac‐to‐ac power converter capable of achieving bidirectional power flow as well as drawing and feeding three‐phase sinusoidal input (supply‐side) and output (motor‐side) currents with any power factor at both sides. This paper discusses active dc‐capacitor‐voltage control applied to the low‐speed, high‐torque motor drive. A specially designed downscaled system combining a 320‐V, 38‐Hz, 6‐pole, 15‐kW induction motor with a 400‐V, 15‐kW TSBC is constructed and tested to confirm the validity of the motor drive. Experimental waveforms obtained from the downscaled system confirm stable operation with the rated load torque across a range from a standstill to the rated speed, including satisfactory start‐up performance.     

A passive EMI filter with access to the ungrounded motor neutral line: direct connection of a general‐purpose inverter to a three‐phase grounded voltage source

This paper proposes a small‐sized passive EMI filter for the purpose of eliminating high‐frequency shaft voltage and ground leakage current from an AC motor. The motor is driven by a general‐purpose PWM inverter connected to a three‐phase grounded voltage source. The passive EMI filter requires access to the ungrounded neutral point of the motor. This unique circuit configuration makes the common‐mode inductor effective in reducing the high‐frequency common‐mode voltage generated by the PWM inverter with a carrier frequency of kHz. As a result, both high‐frequency shaft voltage and ground leakage current can be eliminated very efficiently. However, the common‐mode inductor may not play any role in reducing the low‐frequency common‐mode voltage generated by the diode rectifier, so that a low‐frequency component still remains in the shaft voltage. Such a low‐frequency shaft voltage may not produce any bad effect on motor bearings. The validity and effectiveness of the EMI filter are verified by experimental results obtained from a 200‐V 5‐kVA laboratory system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 80–87, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20243     

Thermoirreversible Characteristics of Curdlan Gels in a Model Reduced Fat Pork Sausage

Dynamic viscoelasticity and thermal characteristics of a model reduced fat pork sausage containing curdlan were investigated. Curdlan formed thermoirreversible gels during preparation of sausage at end point temperatures that were within the range in which such gels usually transform from thermoreversible to thermoirreversible. Dynamic viscoelasticity of curdlan gels and thermal characteristics of curdlan aqueous suspensions were analyzed to help explain the physicochemical behavior of curdlan gels in sausage. Once formed curdlan gels exhibited stronger thermoirreversibility with increasing concentrations. The thermoirreversibility could be attributed to the curdlan concentration being higher than the maximum theoretical curdlan to water ratio.     

Amino Acid Composition of Protein Fractions Extracted from Phaseolus Beans and the Field Bean (Vicia faba L.)

Protein fractions were extracted sequentially with 2% sodium chloride, 30% isopropyl alcohol, 4% lactic acid and 0.5% potassium hydroxide from three varieties of adzuki beans, kafae and red kafae bean, three varieties of lima beans and red lima bean, two varieties of kidney beans and field bean that were grown in the tropics and sub-tropics. The sodium chloride extract had the highest range of protein concentration (51.2 to 81.4%). The sodium chloride extract was separated into two fractions based on solubility in water. The amino acid compositions of the flour from the seed and of the two fractions from the sodium chloride extract were determined. High contents of lysine, aspartic acid, glutamic acid and leucine were obtained, whereas the sulphur-containing amino acids contents were low.     

RAPID MESOCARP CELL ELONGATION ENHANCES GUMMING SYNDROME IN JAPANESE APRICOT (PRUNUS MUME SIEB. ET ZUCC.) FRUIT

ABSTRACT

Japanese apricot (Prunus mume Sieb. et Zucc.) ‘Benisashi’ fruit tends to show the physiological disorder of a gumming syndrome, while the fruit known as ‘Nanko’ rarely show this. The accumulated gum becomes a solid gel during the processing period and the commercial value of the mume pickle is consequently decreased. In the present experiment, gum accumulation in the mesocarp tissue and the cell size of the tissue during fruit growth were observed in the two cultivars. In mid‐May, the initiation of the gum duct was observed in vascular bundles in the mesocarp tissue of the two cultivars and plant gum was then observed to accumulate in the duct. No difference in these phenomena was observed between the cultivars until late May. Thereafter, ‘Benisashi’ developed a gum lump visible to the naked eye during Stage III, while the gum lump of ‘Nanko’ did not develop to the visible size as shown in ‘Benisashi’; the lumps could not be confirmed with the naked eye until the mature stage. ‘Benisashi’ showed more rapid fruit growth compared with ‘Nanko’ during Stage III due to explosive mesocarp cell elongation close to the endocarp. Moreover, the rate of gumming fruit of ‘Benisashi’ was higher in bigger fruits than smaller ones. These results indicate that the peculiar cell growth of ‘Benisashi’ fruit may accelerate gum lump formation.

PRACTICAL APPLICATIONS

Gumming syndrome affects the quality of mume pickle. In this experiment, we investigated the mechanisms of gum accumulation in fruit flesh. ‘Benisashi’, which frequently shows the gumming syndrome, presented rapid inner mesocarp cell growth on fruits developing Stage III. This peculiar cell growth may accelerate gum lump formation. Therefore, we have to prevent the cultivational misconduct that induces rapid fruit growth in this period to suppress the gumming syndrome and to increase the commercial value of mume pickle. Moreover, this knowledge is also important in order to breed the new cultivars which do not contain the gumming syndrome.