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61.
Peter Ekholm Petri Lehmus Esa Kokko Matti Haukka Jukka V. Seppl Carl‐Eric Wiln 《Journal of polymer science. Part A, Polymer chemistry》2001,39(1):127-133
The synthesis and characterization of rac‐[ethylenebis(1‐(tert‐butyldimethylsilyl)‐3‐indenyl)]zirconium dichloride ( 3 ) is reported. The silyl substituted 3 /MAO was compared to its siloxy substituted analogue ( 4 ) in ethylene homo‐ and in ethylene‐1‐hexene copolymerizations to elucidate the effect of the heteroatom on polymerization performance. The influence of monomer and cocatalyst concentration and the polymerization temperature was investigated. The oxygen between the indenyl ligand and the bulky tert‐butyldimethylsilyl group in the siloxy substituted 4 /MAO was found to have a positive influence on polymerization activity and copolymerization performance. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 127–133, 2001 相似文献
62.
多载波通信系统仿真中的EESM和MI-ESM方法 总被引:2,自引:0,他引:2
介绍了在OFDM系统仿真中链路级仿真和系统级仿真之间的映射方法,主要探讨了两种基于有效SINR映射的方法:指数有效SINR映射(EESM)和互信息有效SINR映射(MI—ESM)。着重阐述了这两种方法如何把多状态信道变成单状态信道以及为什么这种有效单SINR方法能够表示多个子载波SINR信道性能,同时也重点研究这两种方法的主要优缺点以及它们对RRM算法设计的影响。而且,也提及了如何去构建链路和系统级映射表(MCS,SINR,BLER)。 相似文献
63.
Alexey Kirilin Päivi Mäki-Arvela Matthias Rupp Esa Toukoniitty Narendra Kumar Krizstian Kordas Leonid M. Kustov Tapio Salmi Dmitry Yu. Murzin 《Research on Chemical Intermediates》2010,36(2):193-210
One-pot synthesis of R-1-phenylethyl acetate was investigated starting from acetophenone hydrogenation performed over Pd/Al2O3 and PdZn/Al2O3 catalysts followed by acylation of the intermediate secondary alcohol, R-1-phenylethanol, over an immobilized lipase. Furthermore, the performance of a third type of catalyst, Ru supported on hydroxyapatite
(HAP) was evaluated for racemization of S-1-phenylethanol in one pot together with the two other catalysts. The main objectives of this work were to separate the effects
of different catalysts and to reveal the reaction mechanism. For this purpose not only acetophenone, but also (R,S)-1-phenylethanol, S-1-phenylethanol, R-1-phenylethyl acetate, and styrene were used as reactants in combination with Pd/Al2O3, lipase and Ru/HAP as catalysts. The results revealed that the main side product, ethylbenzene, was formed in two different
ways, via dehydration of (R,S)-1-phenylethanol to styrene, followed by its rapid hydrogenation to ethylbenzene, and via debenzylation of the desired product,
R-1-phenylethyl acetate to ethylbenzene. The true one-pot synthesis, however, was demonstrated over Shvo’s catalyst, but Ru/HAP
was not sufficiently active in the racemization step. Ru/Al2O3 was a promising catalyst for racemization of S-1-phenylethanol and for dynamic kinetic resolution of (R,S)-1-phenylethanol, when using only small amounts of the acyl donor ethyl acetate. The challenge in racemization is that the
activity of heterogeneous Ru catalysts was inhibited by esters. 相似文献
64.
Faulhuber and Steinerberger conjectured that the logarithmic derivative of has the property that is strictly decreasing and strictly convex. In this small note, we prove this conjecture. 相似文献
65.
Umar Suleiman Dauda NikNoordini NikAbdMalik Mazlina Esa Kamaludin Mohd Yusof Mohd Fairus Mohd Yusoff Mohamed Rijal Hamid 《电子科技学刊:英文版》2016,14(2):126-132
Parameter estimation of signals of universal software radio peripheral (USRP) devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize the closed loop feedback algorithm where the receiver needs to send the received signal strength (RSS) values periodically to the beamforming node so as to take advantage of energy conservation, the frequency and phase of these signals should be estimated before smoothening by nonlinear filters. This article presents the estimation of the frequency offsets of a Gaussian minimum shift keying (GMSK) signal from N210 USRP devices in real time by using the Radix-2 fast Fourier transform (FFT) algorithm in GNURadio. For these green communications devices, most of the needed hardware parts have been software defined, thereby reducing the supposed energy consumption. The frequency offsets from reference carrier frequencies of 900 MHz and 2.4 GHz are less than 3 kHz each before the estimation, but the average offsets are 45 Hz and 100 Hz after the estimation, respectively. The high offset value experienced with the 2.4 GHz carrier was due to consistent interference from devices on that same frequency. 相似文献
66.
The 1H and 13C{1H} chemical shifts and 1H spin–spin couplings of sulfur mustards, nitrogen mustards, and lewisites scheduled in the Chemical Weapons Convention, and those of bis(2‐chloromethyl)disulfide, were determined in CDCl3, CD2Cl2, and (CD3)2CO. Accurate parameters of this kind of series can be used for evaluating the current molecular modeling programs and the chemical shift and coupling constant prediction possibilities of the programs. Several prediction tests were made with commercial programs, and the results are reported here. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
67.
68.
Heikki Haario Aki Kallonen Marko Laine Esa Niemi Zenith Purisha Samuli Siltanen 《Mathematical Methods in the Applied Sciences》2017,40(18):6649-6669
A two‐dimensional sparse‐data tomographic problem is studied. The target is assumed to be a homogeneous object bounded by a smooth curve. A nonuniform rational basis splines (NURBS) curve is used as a computational representation of the boundary. This approach conveniently provides the result in a format readily compatible with computer‐aided design software. However, the linear tomography task becomes a nonlinear inverse problem because of the NURBS‐based parameterization. Therefore, Bayesian inversion with Markov chain Monte Carlo sampling is used for calculating an estimate of the NURBS control points. The reconstruction method is tested with both simulated data and measured X‐ray projection data. The proposed method recovers the shape and the attenuation coefficient significantly better than the baseline algorithm (optimally thresholded total variation regularization), but at the cost of heavier computation. 相似文献
69.
Anne Silset Geir Rune Flåten Herman Helness Esa Melin Gisle Øye Johan Sjöblom 《Journal of Dispersion Science and Technology》2013,34(3):392-408
A matrix of 30 crude oils have been analyzed to investigate if there is any correlation between the physiochemical properties of the crude oils and the quality of the produced water. As an approach to study produced water quality, oil. and brine water (3.5 wt%) have been mixed together, and transmission profiles from the separation process have been investigated by means of Turbiscan LAb. The Turbiscan LAb enables the study of stability of colloidal dispersions without any dilution or modification of the sample. The oil-in-water emulsions (30:70) were made by mixing oil and water at low speed to be sure that they separate within a short period of time. Drop size distributions were investigated for all crude oil emulsions by using a Coulter Counter (COULTER Multisizer II). The correlations between transmission profiles and crude oil characteristics were made by using principal component analysis (PCA), a method that helps visualize the most important information contained in a data set and find combinations of variables that describe major trends. A Vortoil K-liner hydrocyclone connected to a mixing rig has been used to separate oil and water in larger scale experiments. The objective with these experiments was to compare the results with separation experiments done at bench scale. Six crude oils have been investigated at the separation rig, and both droplet size distribution and dispersed oil concentration have been performed. The main conclusions from this work are that Turbiscan LAb is a suitable technique to study the separation of oil-in-water with good reproducibility. The results from the multivariate data analysis show that the crude oils group according to if they are light or heavy and according to if they get high or low transmission. From the larger scale experiments it has been shown that the droplet sizes, oil/water density differential, and viscosity have a significant impact on separation efficiency. 相似文献
70.
Gongnan?Xie Bengt?SundénEmail author Lieke?Wang Esa?Utriainen 《Heat and Mass Transfer》2011,47(1):45-57
One way to cool gas turbine tips is to design serpentine passages with 180° turns inside the blades to fully utilize the coolant
potential. It is therefore a desire to improve the cooling of the blade tips to ensure a long durability and safe operation.
In the present work, a two-pass channel with a 180° turn and various arrays of pin-fins mounted internally on the tip-cap
is considered. The effects of pin-fin height, diameter and pitches on the heat transfer enhancement and pressure drop are
investigated numerically. The nominal ratio of height to diameter (H/D) of the pin-fins is 2, and the ratio of tip clearance
to pin-fin height is about 10. The inlet Reynolds numbers based on hydraulic diameter are ranging from 100,000 to 600,000.
Details of the three dimensional fluid flow and heat transfer over the pin-finned tips are presented. The overall performances
of various tips are compared. It is found that due to the combination of turning, impingement and pin-fin crossflow, the heat
transfer coefficient of the pin-finned tips is up to a factor of 2.1 higher than that of the smooth tip. This augmentation
is achieved at the expense of a penalty of pressure drop around 30%. Results show that the magnitude of the heat transfer
enhancement depends upon pin-fin configuration and arrangement. It is suggested that pin-fins are suitable to enhance the
blade tip heat transfer and thus to improve the tip cooling. 相似文献