An improved analysis of experimental data from 125 I hot-line autoradiographs: allowing for the effects of background grains

In this paper we suggest a new statistical method of correcting the results of hot-line experiments for the effects of background sources and we use the new method to reassess the adequacy of three probability distributions proposed in the literature for image spread from line sources. The data are from sources labelled with ¹²⁵I in semi-thin resin sections 0·4-0·8 μm in thickness. The new method reveals that two of the models describe the empirical distributions more closely than earlier analysis had suggested, and it confirms an increasing relationship between half distance of image spread and the thickness of the source. However, it also confirms that considerable ‘inter hot-line’ experimental variation remains, even after background correction. This suggests that multiple experiments are needed to produce reliable estimates of half distance.     

电力设备绝缘油的检验

充油设备绝缘油的质量与其能否正常运行有着很大关系。绝缘油在氧气、湿度、高温、阳光、强电场和杂质的作用下,性能逐渐变坏,因此必须定期对绝缘油进行各项试验,以保证设备的安全运行。综述了绝缘油的性能和检验方法绝缘油的检验方法。     

变压器现场换油的探讨

变压器油作为变压器绝缘和冷却的重要介质，其质地的好坏直接关系到变压器的安全稳定运行。随着油质分析技术的提高，变压器油中的污染而使介损升高已成为人们关注的问题。因而探讨了变压器的现场验收及其换油等问题     

Determination of secondary electron spectra from insulators

A new technique for the determination of secondary electron (SE) spectra of insulators in a scanning electron microscope environment is presented. It is based on a capacitatively coupled charge measurement by subjecting the insulating film to a controlled pulsed electron beam. With the use of a planar grid analyzer configuration, an algorithm is used to estimate the SE spectrum based on normalized values of the S-curve obtained. Secondary electron spectra from several insulating materials employed in integrated circuit manufacturing, including silicon nitride (Si3N4), AZ 1350J photoresist, and pyralin polyimide, have been measured.     

Application of fluorescence emission ratio technique for transformer oil monitoring

In this work a new fluorescence emission measurement technology was introduced and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate it for the oil oxidation measurement of electrical insulating oil. The oxidation characteristics of insulating oil were found to be fairly represented by the titration method and IR spectroscopy, and the results are comparable to a change in the fluorescence emission ratio that is defined as the shift in fluorescence intensity in the measured wavelength range. The result also shows that by the measurement of fluorescence emission ratio, it is possible to detect the oxidation of oil relatively earlier than by other methods. This study suggests that the developed technology can provide sufficient information for evaluating the insulating oil quality, and that the developed FER sensor can be used as an effective condition monitoring device of electrical insulating oil oxidation.     

A systematic investigation of the charging effect in scanning electron microscopy for metal nanostructures on insulating substrates

Scanning electron microscopy is perhaps the most important method for investigating and characterizing nanostructures. A well‐known challenge in scanning electron microscopy is the investigation of insulating materials. As insulating materials do not provide a path to ground they accumulate charge, evident as image drift and image distortions. In previous work, we have seen that sample charging in arrays of metal nanoparticles on glass substrates leads to a shrinkage effect, resulting in a measurement error in the nanoparticle dimension of up to 15% at 10 kV and a probe current of 80 ± 10 pA. In order to investigate this effect in detail, we have fabricated metal nanostructures on insulating borosilicate glass using electron beam lithography. Electron beam lithography allows us to tailor the design of our metal nanostructures and the area coverage. The measurements are carried out using two commonly available secondary electron detectors in scanning electron microscopes, namely, an InLens‐ and an Everhart–Thornley detector. We identify and discriminate several contributions to the effect by varying microscope settings, including the size of the aperture, the beam current, the working distance and the acceleration voltage. We image metal nanostructures of various sizes and geometries, investigating the influence of scan‐direction of the electron beam and secondary electron detector used for imaging. The relative measurement error, which we measure as high as 20% for some settings, is found to depend on the acceleration voltage and the type of secondary electron detector used for imaging. In particular, the Everhart–Thornley detectors lower sensitivity to SE₁ electrons increase the magnitude of the shrinkage of up to 10% relative to the InLens measurements. Finally, a method for estimating charge balance in insulating samples is presented.     

非电参数对非导电工程陶瓷电火花磨削效果的影响

开发了一种新的非导电工程陶瓷电火花磨削工艺,对不导电的A1203工程陶瓷进行了加工实验研究,给出了一些非电参数对材料去除率和工件表面粗糙度的影响规律,并进行了理论分析.结果表明,非电参数在该加工工艺中起到举足轻重的作用,设置合理可以大大提高材料去除率,并能改善工件表面质量.     

城市燃气管网的安全性评价

对某市燃气管网的主要失效形式进行了统计分析,提出了燃气管网的检验检测方法,并对低压庭院管道进行了开挖检测。根据有关规范建立了燃气管网的安全等级划分方法,并采用蒙德评价法建立了燃气管网单元的危险性评价方法。对低压庭院管道的安全性评价表明,采用蒙德评价法与安全等级划分方法对燃气管网的安全性评价结果基本一致。     

An evaluation of the gassing tendency under electrothermal stress of some dielectric liquids

It is known that, under electrical or thermal stress, dielectric liquid produces gas. The performance of oil cooled, insulated, or impregnated electrical equipment such as transformers, cables, or capacitors, is affected by the presence of these small gaseous bubbles, which can give rise to partial discharges and to eventual insulation breakdown. Therefore, the gassing properties of an insulating liquid, i.e. its tendency to absorb or evolve gases, have been recognised as a factor of major importance in characterising dielectric liquids. The transition from gas absorption to gas evolution can occur at different temperatures and electrical stresses for different liquids. The effects of temperature, electrical stress, and ageing on gassing tendency have been well studied. Efforts have also been made to correlate the aromatic content of oil with a gassing tendency. However, such studies are limited to mineral insulating transformer oil. In the present work, an effort has been made to study the gassing characteristics of some common dielectric fluids, including linear alkyl benzene (LAB), silicone oil, and capacitor oil, along with some naphthenic and paraffinic transformer oils.     

A new designed hot-line work robot for sweeping post insulators at high-voltage

In this paper, a new hot-line robot that can sweep post insulators at high voltage is introduced. Working at high-voltage, the robot had to be designed specially because there was no similar one before. To ensure insulation, we use methods of insulated elevating scissors mechanism, insulated hydraulic system, two-level control system, fiber optic and wireless communication system, etc. The robot integrates technologies of insulation at high-voltage, hydraulic driving, insulated material, wireless communication, vision, autocontrol, etc.     

PHOTOACOUSTIC SPECTROSCOPY OF LAYERED SAMPLES: PHASE-DETECTION TECHNIQUE

Abstract

Depth profiles of double layer biological samples, obtained by photoacoustic spectroscopy, have been studied using the phase-resolved method. The application of the method was demonstrated by insulating out the spectra of the cuticle and the pigment layers of a lettuce leaf. Using this method, we were able to monitor the phase shift between the cuticle and the pigment layers as a function of the time elapsed after herbicide spraying. The temporal changes occurring in lettuce leaves under the action of dehydration were also investigated.     

汇流环绝缘失效分析及绝缘材料选用

针对在恶劣的实际工况中,雷达汇流环较易发生绝缘失效故障的现象,从绝缘材料漏电起痕的角度分析了汇流环绝缘失效的机理,研究了绝缘材料漏电起痕指数(CTI)对汇流环绝缘性能的重要影响,并以CTI作为考量指标,对目前汇流环常用绝缘材料的绝缘性能进行了分析,提出了在汇流环设计中绝缘材料的选用原则,为雷达汇流环的绝缘性能设计提供了参考.     

Investigation of heat transfer in an oil cooled piston with and without ceramic insulation on crown face

A numerical method is presented for calculating the temperature fields in a semi-adiabatic diesel engine piston having a cooling oil canal. The crown face of the piston is coated by a 2 mm thick oxide based ceramic insulating material. The non-ideal thermal contacts between the piston circumference and cylinder wall are also considered. A detailed analysis has been given for estimating the boundary conditions of the cylinder-piston assembly of an internal combustion engine. The isothermic distribution in the piston body and the heat flow rate through the different cooling media at four different engine loads have been depicted both for the cases with and without insulation coating. The results indicate a reduction (12–30%) in heat loss through the piston by use of an insulation coating at the piston crown face, assuming that both the heat transfer process from and the temperature of the combustion products remain unchanged.     

复合型真空多层绝热低温容器真空丧失后热响应研究

搭建了高真空多层绝热低温容器完全真空丧失研究实验台,分别利用干燥氮气及空气作为破空气源,进行了低温容器发生完全真空丧失事故后排放试验和无排放试验。排放试验中测得了复合型真空多层绝热低温容器在发生完全真空丧失事故后的排放率并计算了热流密度;无排放试验中测得了复合型真空多层绝热低温容器在发生完全真空丧失事故后的压力上升情况和液体的温度分层。试验结果表明,导入复合型真空多层绝热低温容器绝热夹层的气体种类对其完全真空丧失后的响应有很大的影响。     

Note: Laser ablation technique for electrically contacting a buried implant layer in single crystal diamond

The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.     

基于巡检机器人的变电站设备运行状态监测技术

为及时排查设备故障问题、找出可能存在的安全隐患,提出一种基于巡检机器人的变电站设备运行状态监测技术。巡检机器人通过红外摄影仪采集设备温度数据,凭借可拓展标记语言编辑设备序列、服务器名称及位置信息,明确设备中绝缘介质以及相关缓冲逻辑节点,组建具有周期性号召的数据库,归一化及加权处理输入分量因子,得到运行状态特征向量,利用故障树模型预测和排查设备风险状态,挖掘故障底层原因,从根源解除设备故障隐患,完成全面监测。仿真实验证明,所提方法监测准确度高、用时更短、误报率情况少,可适用性更好。     

不同流场构型对微细螺旋孔电解加工的影响

为了研究微细螺旋孔电解加工中不同流场构型对加工效果的影响,首先介绍了一种微细螺旋孔电解加工（ECM）用工具电极的制作工艺方法;然后,通过改变电极绝缘层厚度构造不同的螺旋孔电解加工流场构型,并对其进行了数值分析;最后,通过电解加工实验对分析结果进行了验证。研究结果表明,在其它条件不变的情况下,涂层厚度越厚,加工效果越好。     

Synergetic effect of BN for the electrical conductivity of CNT/PAN composite fiber

Carbon nanotube (CNT) fillers in composite materials improve electrical conductivity, thermal stability, and mechanical properties. Boron nitride (BN) is an insulating material that is also thermally stable. Therefore, CNT and hexagonal boron nitride (hBN) fillers have been used to obtain composite materials’ high electrical conductivity. In this study, CNT-hBN/polyacrylonitrile (PAN) fibers were spun using simple wet-spinning and the effect of hBN on the electrical conductivity of the CNT-hBN/PAN composite was investigated. Contrary to predictions, as the content of the insulating material, BN, increased up to 15 wt%, the electrical resistance of the composite fiber decreased.

     

Effects of shielding coatings on the anode shaping process during counter-rotating electrochemical machining

Electrochemical machining (ECM) has been widely used in the aerospace, automotive, defense and medical industries for its many advantages over traditional machining methods. However, the machining accuracy in ECM is to a great extent limited by the stray corrosion of the unwanted material removal. Many attempts have been made to improve the ECM accuracy, such as the use of a pulse power, passivating electrolytes and auxiliary electrodes. However, they are sometimes insufficient for the reduction of the stray removal and have their limitations in many cases. To solve the stray corrosion problem in CRECM, insulating and conductive coatings are respectively used. The different implement processes of the two kinds of coatings are introduced. The effects of the two kinds of shielding coatings on the anode shaping process are investigated. Numerical simulations and experiments are conducted for the comparison of the two coatings. The simulation and experimental results show that both the two kinds of coatings are valid for the reduction of stray corrosion on the top surface of the convex structure. However, for insulating coating, the convex sidewall becomes concave when the height of the convex structure is over 1.26 mm. In addition, it is easy to peel off by the high-speed electrolyte. In contrast, the conductive coating has a strong adhesion, and can be well reserved during the whole machining process. The convex structure fabricated by using a conductive iron coating layer presents a favorable sidewall profile. It is concluded that the conductive coating is more effective for the improvement of the machining quality in CRECM. The proposed shielding coatings can also be employed to reduce the stray corrosion in other schemes of ECM.     

Multi-cavity Tire

This new utility model relates to a vehicle tire, especially to the multi-cavity tire which the inside of tire is divided into many cavities. The feature of this new utility model is that, several interlayers are provided in the direction of the tire＇s circumferential cross section, which divides the tire into many cavibies. The center of the tire cavity is provided with the ring-like rubber pipe, which passed through each interlayer of the cavity. There is an air hole on the rubber pipe. If this tire is punctured during the vehicle runing, the air is leaked from the fracted cavity, but the air in other cavities would flow out through the hole on the rubber pipe, so the flpw is very slow, therefore it can play the cushion role, and it also can reduce the burst power, because the air in each small cavity is little.