Use of pyrogenic silicas for petroleum oil polar fraction characterisation. Fourier transform infrared spectroscopy and microelectrophoresis studies

In the power transformer, the presence of polar or charged species in the insulating oil can cause failure and electric discharges. Solid substrates such as silica can be used to extract the polar species and to refine the oil in order to prevent future failure in the power transformer. However, the use of silica for petroleum oil separation and refining will depend on the silica characteristics such as surface charge, surface composition, specific surface area and particle size.Various pyrogenic silicas having various specific surface areas (49-200 m² g⁻¹) and particle sizes (207-500 nm) were used to extract the polar fractions from the neat transformer insulating oils (a new, NO, and used, UO2, oils). The oil covered silica samples were investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy in the range 4000-600 cm⁻¹. The bare silica surfaces present two main hydroxyl components, a sharper peak at 3745 cm⁻¹, I₃₇₄₅, due to isolated silanols and a second broad, which spreads over 3745-3000 cm⁻¹, I_3745-3000, due to H-bonded silanols. The relative intensities of the two components, I₃₇₄₅/I_3745-3000, varied for the bare and the oil covered silicas depending on the solid surface characteristics. The adsorption of the NO polar fraction onto silica leads to strong reduction in intensity of the sharper peak in favour of the broad one. However, the adsorption of the UO2 polar fraction onto silica leads in all cases to the decrease in the intensity of the both silica OH components. Further, the UO2 adsorption on the silica leads to the apparition of a broad peak at low frequency in the region 3250-3300 cm⁻¹ which, is due to the associated phenolic groups of UO2 oil polar fraction. The analysis of the DRIFT spectra for various samples indicates that the oil polar fraction resembles to asphaltenes compounds.The microelectrophoresis method used to investigate the surface charge at the water/oil polar fraction covered silica interface, indicates negatively charged particles. Further, the negative charge increased with the pH, as resulting from the increase of the ionisation and/or the amount of the oil polar carboxylic and phenolic groups. The oil polar fraction, i.e. the asphaltene components, in contact with both the silica surface and water at high pH values rearrange, due to their amphiphilic character.Finally, the use of the silica substrates seems to be suited to extract and analyse polar species present in petroleum oil. A correlation is found between the nature of the oil, its functionalities, and the magnitude of its zeta potential value at the water/oil covered silica interface.     

Wiener models of direction-dependent dynamic systems

Analysis of systems with direction-dependent dynamics is currently limited to cases in which the dynamics in the two directions of the output are first order; results for such systems have been published for both pseudo-random maximum-length binary (MLB) and inverse-repeat maximum-length binary (IR-MLB) inputs. These relatively limited analytical results make it useful to examine alternative ways of modelling such systems and in this paper, Wiener models are considered for this purpose. Methods for optimising the Wiener model parameters by matching the system and model cross-correlation functions, outputs, and discrete Fourier transforms of the outputs are considered, and the results are compared. These methods are also applied to a first-order direction-dependent system with a maximum-length ternary (MLT) input, for which no analytical results are currently available, and to a second-order system with an IR-MLB input.     

Instability of zeolite Y supported cobalt sulfide hydrotreating catalysts in the absence of H2S

Ion exchanged CoNaY was sulfided at 473 and 673 K and subsequently heated in He at 673 and 773 K. The resulting samples were characterized by means of overall sulfur analysis, temperature programmed Ar treatment and Fourier transform infrared spectroscopy. It was shown that during He flushing at sufficiently high temperature a protolysis reaction occurs resulting in the decomposition of Co sulfide into Co²⁺ ions and H₂S.     

Modified Imidazoles: Degradation Inhibitors and Adhesion Promoters for Polyimide Films on Copper Substrates

Polyimide films on copper substrates that are exposed to elevated temperatures and an oxidizing environment will be subject to degradation. In order to halt this degradation without changing the properties of the system, a polymeric agent could be placed between the polyimide and the copper. This paper will investigate three such materials that will not only slow down the degradation of the polyimide and the oxidation of the copper, but will also improve adhesion within the system. Fourier transform infrared reflection-absorption spectroscopy (FTIR-RAS) will be used to investigate the polyimide/polymeric agent/copper system.     

Fast convergent study on potential－harmonic method of directly solving Schrodinger equation in few－body systems

Ｆａｓｔｃｏｎｖｅｒｇｅｎｔｓｔｕｄｙｏｎｐｏｔｅｎｔｉａｌ－ｈａｒｍｏｎｉｃｍｅｔｈｏｄｏｆｄｉｒｅｃｔｌｙｓｏｌｖｉｎｇＳｃｈｒｏｄｉｎｇｅｒｅｑｕａｔｉｏｎｉｎｆｅｗ－ｂｏｄｙｓｙｓｔｅｍｓＷａｎｇＹｉ－Ｘｕａｎ（王沂轩）ａｎｄＤｅｎｓＣｏｎｇ...     

有自聚焦功能的付里叶计算全息

在制作付里叶计算全息过程中，加入适当的二次位相因子，使此种全息图在相干光照明下就可预定的位置上只再现一个像，省略了过去丙现此种计算全息图必要的付里叶透镜，并且使两个互为共轭像分离，从而拓宽了此种计算全息的应用领域，实验结果与理论分析相符。     

海浪谱的光学探测及信息处理

建立了一套光学——计算机混合处理系统用以分析海浪航空底片,并得到了海浪方向谱和能谱。实验结果与现有的海浪理论符合较好,同时显示了该方法有可能发展成一种实用的实时海浪探测方法。     

IR Radiometry Optical System View Factor and Its Application to Emissivity Investigations of Solid and Liquid Phases

An optical system for fast IR radiometry designed for investigations of thin film thermal properties and pulsed laser melting was analyzed in this work. A methodology for determination of the view factor from calibration measurements was developed. The view factor (0.0255) of the optical system containing two paraboloid mirrors was determined experimentally from calibration measurements on pure metals and metallic alloys. The knowledge of the view factor was then applied to normal emissivity investigations at IR wavelengths. The emissivity of tungsten films prepared by magnetron sputtering was determined for different deposition conditions, varying between 0.036 and 0.071. Liquid phase emissivities of Cu, Mo, Ni, Si, Sn, Ti, and steel were also determined and were found to be higher than solid-state emissivities as predicted from the literature. A knowledge of the liquid-state emissivity of silicon enabled recalculation of the IR signal evolution to the temperature evolution, during and after a nanosecond laser pulse. This was not possible by use of the usual calibration because of silicon’s semi-transparent behavior in the IR range (1–10 μm) in the solid-state phase.     

SISAK快速化学分离装置的建立

SISAK(Short-lived Isotopes Studies by the AKUFVE technique)技术是目前使用最广泛的快速化学分离方法之一,主要应用在短寿命核素的分离和鉴别、超重元素的人工合成以及化学性质研究等方面的工作中.本文简单地叙述了SISAK技术的流程、原理和发展现状,介绍了自行建立的国内第一套基于SISAK技术的快速化学分离装置,并通过从裂变产物中分离短寿命核素这一实例验证了SISAK技术在快速化学分离中的优越性.     

检测骨架图形特征点的新方法

端点、折点、歧点和交点是骨架图形的重要特点是，提出用快速查表法检测侯选特征点，再进行侯选特征点聚集，用局部结构分析，去除假特征点，判别真特征点的类型，并对折点给以大致的定量描述。实验结果表明，该方法能快速有效地找出骨架图形的特征点，在目标识别、字符识别等应用中起着关键作用。