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71.
Molecular dynamics (MD) simulations of-Al2O3, using a pairwise additive interaction potential of Pauling's type with four different radii for aluminum atoms, were analysed in order to determine the influence of the radius on the modification of coordination numbers of A1 relative to the ideal structure, at two different temperatures of 300 and 1500 K. It is found that the best choice is the radius of penta-coordinated aluminum, reproducing structural and vibrational properties of the compound in excellent agreement with experimentally observed properties. 相似文献
72.
The problem of on‐line estimation of the conversion and composition evolutions in a pressurized batch copolymer reactor with temperature and pressure measurements was addressed. The estimation model consisted of mass and energy balances with a pressure equation built from phase‐equilibrium considerations. The application of a nonlinear geometric estimation approach yielded the underlying solvability condition with physical meaning, a straightforward estimator construction, and a conventional‐like tuning procedure. The resulting barocalorimetric estimator was an on‐line dynamic measurement processor with a model‐based predictor and a measurement‐driven corrector, and whose implementation did not require the polymerization rates and heat‐transfer coefficient function dependencies. The technique was tested with a representative laboratory styrene–butadiene system. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 475–482, 2005 相似文献
73.
The main goal of this paper is the design of a novel and robust methodology for calibrating cameras from a single image in sport scenarios, such as a soccer field, or a basketball or tennis court. In these sport scenarios, the only references we use to calibrate the camera are the lines and circles delimiting the different regions. The first problem we address is the extraction of image primitives, including the challenging problems of shaded regions and lens distortion. From these primitives, we automatically recognise the location of the sport court in the scene by estimating the homography which matches the actual court with its projection onto the image. This is achieved even when only a few primitives are available. Finally, from this homography, we recover the camera calibration parameters. In particular, we estimate the focal length as well as the position and orientation in the 3D space. We present some experiments on models and real courts which illustrate the accuracy of the proposed methodology. 相似文献
74.
Electrically conducting blends, based on polypyrrole (PPy) as the conductive polymer and poly(?-caprolactone) (PCL) as an insulating polymeric matrix, were prepared by polymerizing pyrrole (Py) in its vapor state inside the PCL matrix. The roles of specific interactions between blend components as well as the crystallization of PCL matrix in the resulting morphology have been analyzed by Fourier-transform infrared spectroscopy (FTIR), thermo-optical analysis (TOA) and atomic force microscopy (AFM). The results indicate that PPy is located within both the intra and interspherulitic regions of the PCL matrix achieving a well-developed connected network. Compared with amorphous matrices, considerable conductivity (around 1 S/cm) was raised with the crystalline PCL matrix with only a relatively low level of the conductive polymer (∼5%) in the blend. 相似文献
75.
Luis Carlos Ferreira Jr.Marcos A.S. Costa Pedro Ivo C. GuimarãesLuiz Claudio de Santa Maria 《Polymer》2002,43(14):3857-3862
Styrene polymerization was carried out with Ni(acac)2/MAO and Ni(acac)2/SiO2/MAO. The influence of reaction parameters (Al/Ni mole ratio, catalyst concentration, temperature and time polymerization) on styrene polymerization was evaluated. It was observed that both catalytic systems were affected by reaction parameters and that the heterogeneous catalyst presented higher activity than the homogeneous one. Polystyrenes with different molecular weight, stereoregularity and polydispersity were obtained. These results suggest that different active catalyst species could have been present. In addition, two types of methylaluminoxane (MAO) with different molecular weights were also evaluated as cocatalyst. As a result, the catalyst activity and stereospecificity were strongly affected by the MAO type. 相似文献
76.
Summary The Stefan-Winkelmann diffusion technique has been used to determine vapor pressures of high boiling point compound-solvents mixtures. Data are reported at a temperature of 67°C for the mixtures polyphenyl ether (6 rings) — benzene and carbowax 1500 — benzene and at a temperature of 100°C for the mixtures polyphenyl ether (6 rings) — toluene and tricresylphosphate-toluene. The range of concentration is only limited by the appearance of a solid phase, and results are in good agreement with those determined by vapor pressure osmometry.Nomenclature A
Vapour source
- B
Flowing gas phase
- c
Concentration, g-mol/cm3
- DAB
Molecular diffusion coefficient, cm2/s
- hi
Total interface depth, cm
- K
Parameter defined by equation (6), dimensionless
- I
Polymer or high boiling point compound
- MA
Molecular weight
- NAZ
Molar flux, g-mol/(cm2) (s)
- PA
Partial pressure at the interface, atm
- P
Total pressure, atm
- R
Gas constant, (atm) (cm3) / (°K) (g-mol)
- T
Temperature, °K
- t
Time, s
- YA
Molar fraction at the interface, dimensionless
- zo
Initial interface depth, cm
- zi
Drop of the interface depth, cm
- z
Interface position
Greek Letters A
Density of the liquid phase, g/cm3 相似文献
77.
Pedro Luis Mateo Navarro Gregorio Martínez Pérez Diego Sevilla Ruiz 《International journal of human-computer interaction》2014,30(12):946-964
This article describes a novel approach to model the quality of experience (QoE) of users in mobile environments. The context-aware and ratings interaction model (CARIM) addresses the open questions of how to quantify user experiences from the analysis of interaction in mobile scenarios, and how to compare different QoE records to each other. A set of parameters are used to dynamically describe the interaction between the user and the system, the context in which it is performed and the perceived quality of users. CARIM structures these parameters into a uniform representation, supporting the dynamic analysis of interaction to determine QoE of users and enabling the comparison between different interaction records. Its run-time nature allows applications to make context- and QoE-based decisions in real time to adapt themselves, and thus provide a better experience to users. As a result, CARIM provides unified criteria for the inference and analysis of QoE in mobile scenarios. Its design and implementation can be integrated (and easily extended if needed) into many different development environments. An experiment with real users comparing two different interaction designs and validating user behavior hypotheses proved the effectiveness of applying CARIM for the assessment of QoE in mobile applications. 相似文献
78.
Stability and performance features of linear PI compensation for continuous bioreactors are studied in this paper. First, it is established that conventional PI control can be represented as the combination of an I/O inverse dynamics feedback with a modeling error dynamic estimator. Then, the analysis of the closed‐loop dynamics carried out with singular perturbation tools shows that PI control can recover the stability and performance induced by exact I/O inverse dynamics feedback controller. The theoretical results are illustrated via a typical numerical example. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
79.
Alaa?S.?Abd-El-AzizEmail author Sarrah?A.?Carruthers Pedro?M.?Aguiar Scott?Kroeker 《Journal of Inorganic and Organometallic Polymers and Materials》2005,15(3):349-359
A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A2+B3 method. The A2 compounds used were common diols, dithiols or dichloroarenecomplexes. B3 compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the
properties of the products was probed. Analysis of the prepared polymers was conducted using 1H and 13C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally
found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C,
corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to
occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures
ranged from 155 to 190°C. 相似文献
80.
Henri Berthiaux Antonio Guttierrez Lavin Julio Bueno De Las Heras Marisol Muñiz Alvarez 《加拿大化工杂志》2007,85(2):158-170
Despite of its general use in industry, particle sedimentation is still a not well understood unit operation. Hydrodynamics is complex in essence, mainly because the possible volumes are depending on the operating conditions, which in turn has consequences on the stability of the equipment in unsteady state conditions. 相似文献