绝缘油离子迁移率的测试及其特性分析

为了正确测量绝缘油的离子迁移率并掌握其随温度的变化特性,重点研究了采用极性反转方法测量绝缘油离子迁移率,探究了电压幅值、极性反转时间对测量结果的影响;测量了3种绝缘油在不同温度下的离子迁移率变化特性,对比分析了不同标准和测量方法所得电导率结果的差异;此外,还对油均衡离子数密度和离子等效半径等重要参数进行了分析和讨论。结果表明,尽管几种不同商用矿物绝缘油具有较为接近的理化参数,但其离子迁移率和活化能大小却差别较大,且各项特性参数会因不同的活化能大小而在不同温度下表现出较大差异。     

基于电压补偿原理的避雷器泄漏试验方法研究

直流参考电压U1mA和0.75倍U1mA下的泄漏电流测量是避雷器交接和例行试验项目之一。220 kV及以上避雷器常采用多节单元,由于避雷器制造工艺、均压环影响等原因,同一相避雷器各单元的伏安特性存在一定差异,当差异较大时,必须拆除引线,分单元进行避雷器直流泄漏试验。在对220 kV及以上避雷器伏安特性进行分析的基础上,提出了1种基于电压补偿原理的避雷器直流泄漏试验方法,设计了1台可调极性直流高压发生器。通过现场实用,验证了试验方法的有效性。     

脉冲电流极性鉴别法在10 kV管型母线局放检测中的应用

提出一种利用脉冲电流的极性鉴别法对管型母线内部局部放电进行定相的检测方法,通过EMTP/ATP仿真验证了理论分析的正确性,最后通过一起案例证实此方法的有效性,具有一定的工程实用价值。     

转换波地震资料处理方法在苏里格地区的应用

在详细分析了转换波资料特征的基础上,以苏里格气田实际采集的多波资料为对象,开展了极性反转、转换波静校正、叠前噪声压制、共转换点道集的抽取等关键处理方法的研究.提出了PS波构造相似法转换波静校正、分频噪声压制技术及共转换点道集抽取解决方案,实际资料的处理结果表明了该方法的正确性及有效性.     

Comparative Study on Reactive Extraction of Nicotinic Acid with Amberlite LA‐2 and D2EHPA

Abstract

The comparative study of reactive extraction of nicotinic acid with Amberlite LA‐2 and D2EHPA in three solvents with different polarity indicated that the extractant type and solvent polarity control the extraction mechanism. Thus, the reactive extraction with Amberlite LA‐2 in low‐polar solvents occurs by means of the interfacial formation of an aminic adduct with 3 or 2 extractant molecules. If solvents with higher polarity are used, each reactant participates with one molecule to the interfacial reaction. The mechanism of reactive extraction with D2EHPA involves in all cases the formation of a salt as the product of the interfacial reaction between one molecule of each reactant.     

After-effects of TFT-LCD display polarity and display colour on the detection of low-contrast objects

Participants performed a word–non-word discrimination task within a car control display emulated on a thin film transistor liquid-crystal display (TFT-LCD). The task simulated an information read-out from a TFT-LCD-based instrument panel. Subsequently, participants performed a low-contrast object detection task that simulated the detection of objects during night-time driving. In experiment 1, words/non-words were presented black-on-white (positive polarity) or white-on-black (negative polarity). In experiments 2 and 3, display colour was additionally manipulated. A positive polarity advantage in the discrimination task was consistently observed. In contrast, positive displays interfered more than negative displays with subsequent detection. The detrimental after-effect of positive polarity displays was strong with white and blue, reduced with amber and absent with red displays. Subjective measures showed a preference for blue over red, but a slight advantage for amber over blue. Implications for TFT-LCD design are derived from the results.

Statement of Relevance: When using TFT-LCDs as car instrument panels, positive polarity red TFT-LCDs are very likely to lead to good instrument readability while at the same time minimising – relative to other colours – the negative effects of an illuminated display on low-contrast object detection during night-time driving.     

Differential effects of magnetic pulses on the orientation of naturally migrating birds

In migratory passerine birds, strong magnetic pulses are thought to be diagnostic of the remagnetization of iron minerals in a putative sensory system contained in the beak. Previous evidence suggests that while such a magnetic pulse affects the orientation of migratory birds in orientation cages, no effect was present when pulse-treated birds were tested in natural migration. Here we show that two migrating passerine birds treated with a strong magnetic pulse, designed to alter the magnetic sense, migrated in a direction that differed significantly from that of controls when tested in natural conditions. The orientation of treated birds was different depending on the alignment of the pulse with respect to the magnetic field. These results can aid in advancing understanding of how the putative iron-mineral-based receptors found in birds'' beaks may be used to detect and signal the intensity and/or direction of the Earth''s magnetic field.     

反馈极性的判断方法--瞬时极性法

反馈技术广泛应用于各工程技术领域，尤其是电子技术领域。在放大电路中采用负反馈，而在波形产生和波形变换的电路中则需要采用正反馈。现介绍运用瞬时极性来准确判断电路反馈极性的方法。     

转换波地震勘探中的最大炮检距设计

从反射系数和动校正拉伸２个方面对转换波勘探最大炮检距设计进行了研究。研究表明，转换波最大炮检距可能大于或小于纵波最大炮检距，这主要取决于纵波和转换波反射系数特征。根据有无临界角以及反射系数中有无极性反转，将纵波和转换波反射模式分成８种，并给出了相应的最大炮检距确定原则与方法。当采用双曲时距方程进行动校正时，转换波的动校正拉伸要小于纵波的动校正拉伸；在相同动校正拉伸下，转换波的最大炮检距大于纵波的最大炮检距。采用高精度的转换波时距方程进行动校正，能够减小动校正拉伸。     

一种用于线阵列系统极性测试的可靠方法

一组线阵列系统的性能在很大程度上取决于其扬声器的正确安装。例如,一个极性错误的单体扬声器可能会明显地影响整个系统的声压和指向性。然而,这种错误的鉴定非常耗时。因此,这就需要一种快速同时又可靠的方法来找出这样的线阵元素。介绍了一种怎样一步一步来检查一个完整的线阵列系统的方法,同时,还能找出引起极性问题的原因。除了理论背景,还描述了一个实际应用的成功案例。