Investigation of Water Tree Degradation in Dry‐Cured and Extruded Three‐Layer (E‐E Type) 6.6‐kV Removed XLPE Cables

Dry‐cured and extruded three‐layer (E‐E type) 6.6‐kV cross‐linked polyethylene (XLPE) cables were introduced into electric power systems more than 30 years ago, but they do not experience failures because of water tree degradation. Also, the degradation index of water treeing for these cables has not been established. Therefore, investigating results of residual breakdown voltage and water tree degradation of these cables will help us plan for cable replacement and determine water tree degradation diagnosis scheduling, and will be fundamental data for cable lifetime evaluation. In this study, the authors measured the ac breakdown voltages of dry‐cured and E‐E type 6.6‐kV XLPE cables removed after 18 to 25 years of operation and observed the water trees in their XLPE insulation. As a result, it was observed that breakdown voltages were larger than the maximum operating voltage (6.9 kV) and the ac voltage for the dielectric withstanding test (10.3 kV). Water trees were mainly bow‐tie water trees and their maximum length was approximately 1 mm. Although the number of measured cables was limited, the lifetime of this type of cable was estimated to be approximately 40 years, even experiencing water immersion.     

New Hybrid‐Excited Motor Using Armature Windings as Field Flux Source

In this paper, a new hybrid‐excited motor is proposed. Its unique feature is that it has no field exciting coil, despite being a type of bypass yoke core (BYC) hybrid‐excited synchronous motor. Based on finite element analysis (FEA), the following facts are clarified. Since the stator coil magnetomotive force (MMF) and claw poles rotate at the same speed and in the same direction, they are motionless relative to each other. Since the claw poles are located at one of its ends near the BYC surface with a gap, it receives immovable magnetization by the stator coil MMF through the BYC; then the claw poles can supply a magnetic field flux via the BYC. This flux via the BYC increases the total torque, because its torque is added the two other torque components: the permanent magnet torque and claw poles reluctance torque. In addition, the magnetic polarity and the amount of the flux of the claw poles can be varied by controlling the armature current phase angle.     

A Verification of Estimation Accuracy of Lightning Current Waveform and Charge Transfer from Measured E‐Field Waveform

To establish effective countermeasures on power facilities against lightning damage, it is necessary to clarify the lightning characteristics such as current parameters at the area of interest. In order to collect lightning current parameters effectively, the authors have observed electric and magnetic field waveforms simultaneously at south Kyushu, where the lightning flash density in summer is high. Based on observed electric field waveforms, the lightning current parameters have been estimated by adopting the Diendorfer–Uman model (DU model) as the return‐stroke model. In this paper, the accuracy of the estimated return‐stroke current waveform is verified by comparison with directly measured return‐stroke current waveform, along with the accuracy of the estimated charge transfer from the electric field waveform measured with a slow antenna.     

Magnetization Properties of Microstructured NiFe Rings Investigated Using Semiconductor/Ferromagnet Hybrid Structures

Magnetization reversal processes in microstructured NiFe rings are studied by fringe-field-induced local Hall magnetometry. This semiconductor-based technique yields a high sensitivity of magnetic stray fields and allows us to detect magnetization hysteresis loops of single NiFe rings. The transition fields can be controlled by the ratio between inner- and outer-ring diameter. Comparison between Hall measurements and numerical simulation suggests that there are four different magnetization states in two integrated rings.

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醋酸菌对C57BL/6J小鼠的酒精性肝损伤的影响研究

该文针对摄入醋酸菌对于酒精性肝损伤的影响进行了评价。将C57BL/6J小鼠（8周龄,雄性,22～27 g）分为对照组（非乙醇给药组）、乙醇组（给予2.5 g/kg乙醇）、乙醇+醋酸菌组（给予2.5 g/kg乙醇+10 mg醋酸菌）,分别每天给药3次,连续经口给药14 d,测定了血清谷草转氨酶（AST）、谷丙转氨酶（ALT）及肝脏油脂浓度。结果表明,与对照组相比较,乙醇组小鼠的AST与ALT浓度,肝脏甘油三酯与胆固醇浓度显著增高（P＜0.05）;乙醇+醋酸菌组的数值则显著低于乙醇组（P＜0.05）。以上结果表明,摄入醋酸菌有可能会减轻酒精性肝损伤。     

Giant spin Hall effect in perpendicularly spin-polarized FePt/Au devices

Conversion of charge current into pure spin current and vice versa in non-magnetic semiconductors or metals, which are called the direct and inverse spin Hall effects (SHEs), provide a new functionality of materials for future spin-electronic architectures. Thus, the realization of a large SHE in a device with a simple and practical geometry is a crucial issue for its applications. Here, we present a multi-terminal device with a Au Hall cross and an FePt perpendicular spin injector to detect giant direct and inverse SHEs at room temperature. Perpendicularly magnetized FePt injects or detects perpendicularly polarized spin current without magnetic field, enabling the unambiguous identification of SHEs. The unprecedentedly large spin Hall resistance of up to 2.9 mOmega is attributed to the large spin Hall angle in Au through the skew scattering mechanism and the highly efficient spin injection due to the well-matched spin resistances of the chosen materials.     

软件质量功能展开法

质量功能展开作为对新产品开发进行质量保证的方法论在日本已被广泛应用。最近，在欧美也被相继引入，笔者们把质量功能开应用到软件开发中进行软件产品的质量保证。本文首先用质量展开的概念模型解释了质量功能展开的基本想法，其次，分析了软件质量保证的问题点；然后，介绍了软件质量功能展开法，最后，总结了软件质量功能展开法的应用效果和今后的课题。     

正膏坊龟苓膏对氧化应激状态的改善作用

目的：研究正膏坊龟苓膏对拘束负荷诱发小鼠应激性肝损伤的保护作用。方法：对于18h 拘束负荷诱发应激性肝损伤的小鼠,分别用赖氏法测定其血浆丙氨酸氨基转移酶(ALT)活性、硫代巴比妥酸法测定肝组织丙二醛(MDA)含量、Griess 化学法测定一氧化氮(NO)含量、荧光酶标仪测定肝组织抗氧化能力指数(ORAC)、HPLC 法测定谷胱甘肽(GSH)含量、比色法测定谷胱甘肽过氧化物酶(GPX)和谷胱甘肽硫转移酶(GST)活性。结果：与拘束应激模型组相比,正膏坊龟苓膏可以明显降低拘束负荷小鼠血浆ALT 活性、肝组织MDA 和NO 含量,有效提高肝组织的ORAC 指数、GSH 含量及GPX 和GST 活性。结论：正膏坊龟苓膏对拘束负荷诱发小鼠应激性肝损伤有一定的保护作用,其作用可能与缓解拘束负荷小鼠的氧化应激水平相关。     

营养型鸡精对拘束应激小鼠免疫功能的改善作用

作者研究了营养型鸡精对拘束负荷小鼠免疫功能的改善作用.将小鼠随机分为正常对照组,拘束应激组,25 mg/kg RU486(糖皮质激素受体拮抗剂组),1 mL/hg BEC(营养型鸡精)组及2mL/hg BEC组,每组10只.除正常对照组外,其余各组连续灌胃给药5 d后拘束负荷18 h,拘束恢复3 d后取血取脾脏测定相关指标.结果显示:BEC不仅可以明显改善拘束应激时小鼠脾脏的损伤,提高脾淋巴细胞总数,而且能显著降低应激小鼠血浆中皮质酮的含量,抑制相关凋亡因子的基因表达,提高线粒体膜电位,减少细胞色素C的释放.BEC可以通过抑制应激小鼠脾淋巴细胞的凋亡来维护脾淋巴细胞数目和功能,改善应激负荷引起的免疫抑制作用.     

Optimization of Switching Phase of a Single‐Phase PWM dc–ac Inverter

The purpose of this paper is to improve the efficiency of the single‐phase pulse width modulation (PWM) dc–ac inverter based on optimization of the switching phase of the PWM. Improvement of the efficiency means improvement of the quality of the output waveform and the conversion efficiency, and reduction of the switching loss. We propose an evaluation method involving minimization of the evaluation function by using the particle swarm optimization algorithm. We improve efficiency by setting a criterion for each index. As a result, the proposed algorithm can reduce high harmonic components in switching times shorter than the conventional triangle wave comparison method. Also, we confirm that the algorithm can improve the quality of the output waveform and the efficiency of conversion.