酸化井产油量时间序列的混沌特征识别

现有的油气井产量预测方法以传统技术经济预测的惯性原理为基础。混沌理论的产生与发展对这种预测原理提出了挑战。目前有关酸化井产量变化混沌特征识别与预测的相关研究还鲜有公开报道。采用相空间重构和关联维数提取技术,对西部某油田一油井酸化后60 d的产油量时间序列研究发现,此井产油量时间序列的饱和嵌入维数和对应的吸引子维数分别为11和2.64,由此说明该井酸化后的生产系统动态演化规律为高维空间中的奇异吸引子,因而产油量变化表现出混沌特征;并且说明影响该井产油量变化的基本变量为3～11个。从而为单井生产系统动力学模型的建立,特别是人工神经网络预测模型的输入层节点数量的确定提供了定量的参考。     

Study of local environment of Ag in Ag/CeO2 catalyst by EXAFS

The combustion synthesized Ag/CeO₂ catalysts have been characterized by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Ag K-edge. It has been found that Ag⁺ like species is present in 1% Ag/CeO₂ catalyst, whereas mostly Ag metal clusters are found in 3% Ag/CeO₂. The analysis of EXAFS spectra indicates that about one oxygen atom is coordinated to Ag central atom at a distance of 2.19 Å in 1% Ag/CeO₂ catalyst along with eight coordinated AgAg bond at 2.86 Å. The AgO bond is absent in 3% Ag/CeO₂.     

Triple Band Annular Ring Loaded Stacked Circular Patch Microstrip Antenna

In this paper a novel structure of annular ring loaded stacked circular patch microstrip antenna is theoretically analysed to observe various parameters such as return loss, input impedance, gain, directivity and radiation pattern. It is found that antenna possess three band of operation which signify the compactness and multiband operation of antenna. The antenna is resonating at three operating frequencies 1.720, 2.950, 3.060 GHz. The proposed theory is verified by simulation using Ansoft’s HFSS and theoretical results are in good agreement with simulated results. The antenna is useful for multi-services operations such as WLAN, GSM, UMTS, and WiMAX services.     

Exergy analysis of helium liquefaction systems based on modified Claude cycle with two-expanders

Large-scale helium liquefaction systems, being energy-intensive, demand judicious selection of process parameters. An effective tool for design and analysis of thermodynamic cycles for these systems is exergy analysis, which is used to study the behavior of a helium liquefaction system based on modified Claude cycle. Parametric evaluation using process simulator Aspen HYSYS® helps to identify the effects of cycle pressure ratio and expander flow fraction on the exergetic efficiency of the liquefaction cycle. The study computes the distribution of losses at different refrigeration stages of the cycle and helps in selecting optimum cycle pressures, operating temperature levels of expanders and mass flow rates through them. Results from the analysis may help evolving guidelines for designing appropriate thermodynamic cycles for practical helium liquefaction systems.     

Synthesis and properties of segmented polyurethane using phenolphthalein as chain extenders

Three series of novel polyurethane elastomers containing phenolphthalein as chain extenders were synthesized. The structure of the polyurethane was analyzed using IR and wide-angle X-ray diffraction studies. Tensile strength and percentage of elongation of all the series of polymers were studied. Thermal decomposition was studied using differential scanning calorimetry. © 1993 John Wiley & Sons, Inc.     

Novel AB crosslinked polymer networks based on 1‐vinylimidazole‐ terminated polyurethane and poly(methyl methacrylate)

1‐Vinylimidazole‐terminated telechelic polyurethanes were prepared from 1‐vinylimidazole and bromine‐terminated polyurethane. This vinyl‐terminated telechelic polyurethane (VTPU) and methyl methacrylate were polymerized in the presence of benzoyl peroxide to prepare novel AB crosslinked polymer networks (ABCPs). These were characterized by spectral, thermal and mechanical studies. The absence of the characteristic peak of vinyl group in infrared spectra of ABCP films confirms the occurrence of crosslinking. Static mechanical testing showed that the tensile strength of ABCP increases with increasing poly(methyl methacrylate) content. Dynamic mechanical studies revealed that ABCPs, at equal compositions of VTPU and methyl methacrylate, show good damping properties. Copyright © 2006 Society of Chemical Industry     

Studies on graft copolymerization of acrylate monomers onto casein

Poly(butyl acrylate) has been graft copolymerized onto casein using potassium peroxydisulfate–ascorbic acid as the initiating system. The proof of grafting has been obtained by ninhydrin test and IR studies. The effects of synthetic variables in the graft copolymerization have been discussed in the light of percent grafting, grafting efficiency, and the rates of polymerization.     

Indicators of ‘innovation as a process’

Innovation as a process is related to the business viewed as a process. A process cannot be captured through the indicators of input/output, which are the most commonly accepted variables. Indicators of technological characteristics also limit the scope of measurement. Moreover, these indicators have often to be constructed upon non-gaussian variables that are not amenable to additive operations. This paper identifies a methodology to identify process innovation variables, some of which are gaussian and some are not. A few simple indicators are then constructed, using additive operations, upon both additive and non-additive variables. The additive variables yield generalisable indicators and the non-additive variables yield self-assessment type indicators. Both types can be used as process performance measurement systems. Examples of the values that these indicators take up, have been shown for nine firms. This vindicates the assumption on the applicability of these indicators.     

Storage stability of solid rocket fuels. 2. Effect of oxidizer loadings

Ageing behaviour, leading to ballistic changes, has been studied as a function of oxidizer loading in polystyrene/ammonium perchlorate solid-propellants. The ageing studies were carried out at 100 °C in air. Change in burning rate decreased as the oxidizer loading increased from 75 to 80%. The change in thermal decomposition rates both at 230 and 260 °C also decreased as the oxidizer loading in the propellants increased. The shapes of the plots of the changes in burning rate and thermal decomposition rate (230 and 260 °C) at different storage times for different oxidizer-loaded propellants seem to be exactly similar. These results lead to the conclusion that the thermal decomposition of the propellant may be responsible for bringing about the ballistic changes during the ageing process. Infrared studies of the binder portion of the aged propellant indicate that peroxide formation takes place during the course of ageing and that peroxide formation for a particular storage time and temperature increases as the loading decreases.     

Reversible,repeatable and low phase transition behaviour of spin coated nanostructured vanadium oxide thin films with superior mechanical properties

Smooth, uniform and crystalline vanadium oxide thin films were deposited on quartz by spin coating technique with four different rpm i.e., 1000, 2000, 3000 and 4000 and subsequently post annealed at 350, 450 and 550?°C in vacuum. Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques were utilized for microstructural characterizations and phase analysis, respectively, for vanadium oxide powder and deposited film. Nanorods were observed to be grown after vacuum annealing. X-ray photoelectron spectroscopy (XPS) technique was utilized to study the elemental oxidation state of deposited vanadium oxide films. Thermo-optical and electrical properties such as solar transmittance (τ_s), reflectance (ρ_s), absorptance (α_s), infrared (IR) emittance (ε_ir) and sheet resistance (R_s) of different thin films were evaluated. Based on the optical characteristics the optimized condition of the film processing was identified to be spin coated at 3000?rpm. Subsequently, the nanoindentation technique was utilized to measure hardness and Young's modulus of the optimized film. The measured nanomechanical properties were found to be superior to those reported for sputtered vanadium oxide films. Finally, temperature dependent phase transition characteristics of optimized vanadium oxide films were studied by differential scanning calorimetry (DSC) technique. Reversible and repeatable phase transition was found to occur in the range of 44–48?°C which was significantly lower than the phase transition temperature (i.e., 68?°C) of bulk VO₂.