Pressure Rise due to SF6 Arcing and Energy Balance in a Closed Container

From an environmental viewpoint, when carrying out internal arc tests on SF₆‐insulated power equipment, it is necessary to prevent SF₆ from being released into the atmosphere or to replace SF₆ with air in accordance with IEC standards. However, the pressure rise and the thermal effect of the hot gas exhausted during arcing when testing in air are still considerably different from those for testing in SF₆. Thus, it is necessary to propose a specific procedure to replace SF₆ with air and to select appropriate parameters for the tests. Therefore, it is desirable to clarify the equivalent conditions causing these phenomena both experimentally and analytically. In this paper, we describe the effect of the charged gas pressure in a closed container on the pressure rise due to air and SF₆ arcing and the ratio of the arc energy to the energy contributing to the internal pressure rise () from an experimental viewpoint. Additionally, to research the energy balance resulting from SF₆ arcing in the container, the energy balance is discussed on the basis of chemical reactions, radiation, and the melting and vaporization of the electrodes. It is found that the maximum pressure rise increases for both gases upon increasing the gas pressure from 0.1 MPa to 0.4 MPa. Subsequently, good agreement with the energy balance was obtained under reasonable assumptions by taking account of the energy components related to the chemical reactions, radiation, and the melting and vaporization of the electrodes. The ratio of the radiation energy loss to the total consumption energy increased upon increasing the charged gas pressure.     

Winding Method to Reduce Vibration and Loss Caused by Fractional Slot of Synchronous Machine

Fractional‐slot windings are widely used in rotating machines in order to improve the output voltage waveform, increase the design flexibility, and gain many other advantages. However, fractional‐slot windings are known to produce different harmonic components such as an even order and/or fractional number of space flux harmonics compared to integral‐slot windings. These harmonics may increase stray losses and cause stator core vibration. This paper describes an analysis of space flux harmonics and proposes new winding methods such as “novel interspersed windings” to reduce these harmonic components. The proposed winding methods were verified by numerical analysis and model tests.     

关于三峡库区周边坡体岩石特性的考察

岩石强度的载荷速率相关性与岩石的时间相关性特性及粘弹性性质密切相关,而且强度的栽荷速率相关性越大,越容易发生蠕变破坏。对于坡体来说,如果构成坡体的岩石的时间相关性很显著．那么即使在比较低的应力下仅施加一点载荷,也容易发生变形。针对三峡库区周边滑坡多发,采集了组成滑坡坡体的4类主要岩石-泥岩、灰岩、泥质砂岩及砂岩。通过室内岩石力学强度试验,获得了不同岩石的强度特性曲线及表示载荷速率相关性的参数n。利用一个试件通过载荷速率交替变换获得了不同应变速率下的应力-应变曲线,从而根据强度的变化率不仅获得了峰值强度的载荷速率相关性,而且还求得了残余强度的载荷速率相关性。在单轴压缩试验中,残余强度的n值与峰值强度的n值有较大的差异,但在三轴压缩试验中两者的差异却不太明显。而且在气干状态下,不管是峰值强度还是残余强度的n值均随着围压的增加而增加。     

开挖扰动区内岩石的压密特性和强度恢复性研究

 利用交替变换荷载速率试验研究压密后岩石试样的强度恢复和荷载速率依存性。首先,分别对田下凝灰岩、来待砂岩、河津凝灰岩和三城目安山岩4种岩石试样在空心圆筒内进行压缩破坏,然后持续轴向加载,压密破坏后的岩石试样。从空心圆筒中推出压密后的试样,进行单轴压缩下的交替变换荷载速率试验,即按一定应变或位移间隔,对同一试样交替施加高低2种不同的荷载速率,得到对应于2种荷载速率的应力–应变曲线。在整个交替变换荷载速率试验过程中,应力随荷载速率的切换而增减。从交替变换荷载速率试验得到的应力–应变曲线上的荷载速率切换点出发,利用3次样条曲线拟合得到2条对应于高低2种荷载速率的应力–应变曲线,并求解强度点处荷载速率依存性参数n。试验结果表明,田下凝灰岩、来待砂岩和河津凝灰岩的强度恢复现象明显,单轴抗压强度随着压密试验中轴向最大荷载的增加而增加,但没有观察到三城目安山岩的强度恢复现象。当压密试验中的最大轴向荷载较大时,压密后的试样的荷载速率依存性与完整试样的基本一致。当压密试验中的最大轴向荷载较小时,从极大和极小2个方面求解荷载速率依存性参数n,得出完整试样的n值介于压密试样的极大值 和极小值 之间,且差值不大。研究结果表明,在进行适当支护之后,随着时间的推移,开挖扰动区内的岩石存在强度恢复的可能性,且今后利用数值模拟考虑开挖扰动区内的岩石强度恢复特性和时间依存性时,在本构方程中可以采用与完整围岩区域一样的参数,从而简化数值模拟程序。     

压密试验中破碎岩石压密特性的本构方程及数值模拟分析

 在以往室内压密试验的基础上,利用变量依存性本构方程对压密试验中试样的压密特性进行数值模拟。本构方程中,假定岩石破坏速度随着破坏接近度Sv的增加而增大;将破坏接近度扩展到三维应力状态,且在破坏接近度为负值的区域,引进强度恢复参数Hp(Hp= –Sv);通过假定压密岩石强度的恢复程度依赖于恢复参数Hp,对本构方程进行修正。从数值模拟结果可以看出：在压密过程中依存性变量? 逐渐变小时,修正后的本构方程可以描述压密过程中岩石的性质;尽管还需进一步研究和完善修正本构方程,但其具有较强的应用前景,能够较好地描述压密试验中破碎岩石的压密特性,解释地下建筑物围岩开挖扰动区的恢复现象。     

Enlargement of Claw Pole Motor Using SMC Cores Divided in the Circumferential Direction

Clawtooth motors have the feature that they can be made thin in the axial direction. This makes them suitable for appliances, automobile accessories, and small‐sized industrial motors. On the other hand, there is a need for thinner HEV and elevator motors and large‐sized industrial motors. In this study, we examined ways of increasing the output of clawtooth motors. We arrived at the following conclusions. (1) The optimal stator structure was determined and the prospects of attaining the target specification of 123 N‐m were determined. (2) Three important manufacturing tasks, assurance of core assembly accuracy, thin coil manufacture, and rotator insertion, were identified. (3) Experimental results and the results of analysis were in agreement with respect to the EMF. (4) The experimental cogging torque results and finite element analysis (FEA) results were in agreement with the FEA results at sixth order but not at second and fourth order. (5) Although the core needed to be divided in the circumferential direction in order to increase its size, it was clear that the influence on the torque was small. (6) Use of a divided core is a good solution for enlargement of clawtooth motors.     

Preventive approach against drug-induced pulmonary fibrosis through the suppression of epithelial-mesenchymal transition

A number of drugs induce pulmonary injury and subsequently lead to serious lung diseases such as pulmonaryfibrosis as the adverse drug reactions. However, an effective preventive approach against drug-induced pulmonary fibrosishas not been established due to poor understanding of common preventive targets in a variety of drugs showing pulmonarytoxicity. Epithelial-mesenchymal transition (EMT), a cellular phenotypic change of the epithelial to mesenchymal state,contributes to the development of pulmonary fibrosis through the conversion of damaged alveolar epithelium intomyofibroblasts. As several drugs with pulmonary toxicity have been reported to induce EMT, EMT serves as a bridgebetween the drugs and pulmonary fibrosis. Accumulated evidence supports the potential of EMT as a preventive targetagainst drug-induced pulmonary fibrosis. Additionally, since there are mechanistic differences between the mainpharmacological effect and EMT induced by the drug, prevention based on EMT suppression would be possible andwould contribute to continuous clinical treatment with the drug to avoid EMT-mediated serious pulmonary fibrosis.Furthermore, targeting EMT seems to be adequate for exerting a preventive effect since EMT in damaged alveolarepithelial cells occurs prior to the development of the pathophysiological state of the whole lung in a bleomycin-inducedlung injury rat model. This viewpoint deals with the benefits and perspectives of preventive approaches against druginduced pulmonary fibrosis through the suppression of EMT, which has rarely been addressed.     

Direct Gas Chromatographic Analysis of Fusel Alcohols, Fatty Acids and Esters of Distilled Alcoholic Beverages

A gas chromatographic method is proposed for the quantitative determination of the main volatile components of distilled alcoholic beverages such as whisky, brandy and rum. This gas chromatographic method enables direct analysis of 23 volatile components, 5 alcohols, 4 acids, 11 esters and 3 aldehydes by simply mixing a beverage sample with internal standards. A fused silica crosslinked 5% phenymethyl silicone capillary column (50 m × 0.31 mm i.d.) is used. The accuracy of the analysis is satisfactory, with the within-day and day-to-day coefficients of variation for most compounds being less than 10%, and the entire procedure can be completed in 40 min.     

Search method for the matrix multiplier time constant and the weighting matrix of the multivariable Popov stability criterion

The multivariable Popov stability criterion contains two arbitrary diagonal matrices which are called the weighting matrix and the multiplier time constant matrix. The choice of the matrices determines the sharpness of the stability criterion obtained. In this paper, a method of searching for adequate values of the matrices is proposed. The method is based on the relation between the M-matrix and the positive-definite hermilian matrix. Numerical examples show that this method is useful in obtaining a sharper stability condition.