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排序方式: 共有149条查询结果,搜索用时 15 毫秒
1.
Dinh Xuan Loc Tran Thi Kim Chi Tran Thu Huong Nguyen Vu Tran Kim Anh Wieslaw Strek Le Quoc Minh 《中国稀土学报(英文版)》2011,(12):1147-1151
Core/shell structured CePO4:Tb(III) @LaPO4 and CePO4:Tb(III) were successfully synthesized in tris(2-ethylhexyl) phosphate(TEHP) and diethylene glycol(DEG) solvents for comparison of the two techniques in open air and closed reaction vessel.Morphology and crystal structure of the core/shell nanophosphors were determined by using X-ray diffraction(XRD) and transmission electron microscopy(TEM) ,which showed that nanophosphors had diameter of about 5-10 nm with the monoclinic monazite phase.The nanophosphors ... 相似文献
2.
Justin D. Littell Wieslaw K. Binienda William A. Arnold Gary D. Roberts Robert K. Goldberg 《Composites Part A》2009,40(12):1846-1862
The reliability of impact simulations for aircraft components made with triaxial braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Methods to characterize the material properties used in the analytical models from a systematically obtained set of test data are also lacking. A macroscopic finite element based analytical model to analyze the impact response of these materials has been developed. The stiffness and strength properties utilized in the material model are obtained from a set of quasi-static in-plane tension, compression and shear coupon level tests. Full-field optical strain measurement techniques are applied in the testing, and the results are used to help in characterizing the model. The unit cell of the braided composite is modeled as a series of shell elements, where each element is modeled as a laminated composite. The braided architecture can thus be approximated within the analytical model. The transient dynamic finite element code LS-DYNA is utilized to conduct the finite element simulations, and an internal LS-DYNA constitutive model is utilized in the analysis. Methods to obtain the stiffness and strength properties required by the constitutive model from the available test data are developed. Simulations of quasi-static coupon tests and impact tests of a represented braided composite are conducted. Overall, the developed method shows promise, but improvements that are needed in test and analysis methods for better predictive capability are examined. 相似文献
3.
4.
Branislaw Jariczuk Wieslaw Wojcik Tomasz Bialopiotrowicz 《Petroleum Science and Technology》2013,31(7):969-987
Abstract Contact angle measurements were carried out in coal / n-alkanes film - air bubble - water systems. Then theoretical an analysis of the equilibrium state of that system was carried out on the basis of the components of the surface free energy of coal of various ranks. The contact angles were measured for four ranks of Polish coal which surfaces were covered with n-alkanes film in the homological series from n-hexane to n-hexadecane. On the basis of the studies and calculations carried out we have concluded that the values of the contact angle depend on the rank of coal, a thickness of n-alkane film and its structure and the presence of water film under the air bubble. It was also found that the changes of the- values of the contact angles measured in the mentioned sytems as a function of the number of contacted air bubbles were similar to those calculated on the basis of the solution of Young equation in function of the surface free energy of coals precovered with n-alkane film. 相似文献
5.
Michele Leonardi Urszula Skomra Monika Agacka Anna Stochmal Katarzyna E. Ambryszewska Wieslaw Oleszek Guido Flamini Luisa Pistelli 《International Journal of Food Science & Technology》2013,48(8):1770-1774
Polish cultivars of hop (Humulus lupulus L.) are well known as aroma and bitter raw material in the brewing industry. To characterise four popular Polish hop cultivars, Lubelski (Lublin), Marynka, Sybilla and Iunga (also known as Junga), the essential oil profiles were determined by gas chromatography/flame ionisation detector (GC‐FID) and gas chromatography/chemical ionisation mass spectrometry (GC‐CIMS) and the alpha/beta acids amounts by high‐performance liquid chromatography/diode array detector (HPLC‐DAD) analysis. In addition, the multivariate statistical analysis of the volatile profiles was performed. The results obtained evidenced qualitative and quantitative differences between the four cultivars studied and the foreign hops described in the literature. Lubelski and Iunga showed the typical chemical profile of the fine‐aroma and high‐alpha cultivars, respectively. In Marynka and Sybilla, the average amounts of alpha acids were similar to the bitter hops, but with a volatile profile characteristics of the fine‐aroma and aroma cultivars respectively. 相似文献
6.
International Maritime Organization regulations forces ship owners to measure NOx emission from ship engines, but standard equipped engine rooms has not installed any usable apparatus to analyze of exhaust gases. In this paper, we propose a method of NOx emission estimation based on the measurements of working parameters of two-stroke ship engine. This estimation consists of both the model enabling to determine a temperature and model of composition of a gas mixture in the combustion chamber of the engine. Application of such model does not require carrying out direct measurements of engine exhaust gases by exhaust gas analyzers. For the developed method, results of engine working parameters should be sufficient to estimate the NOx emission according to IMO regulations. 相似文献
7.
We define the Cartesian product, composition, union and join on interval-valued fuzzy graphs and investigate some of their properties. We also introduce the notion of interval-valued fuzzy complete graphs and present some properties of self-complementary and self-weak complementary interval-valued fuzzy complete graphs. 相似文献
8.
9.
Wieslaw Marszalek 《Circuits, Systems, and Signal Processing》2012,31(4):1279-1296
We present two dual oscillating circuits having a wide spectrum of dynamical properties but relatively simple topologies. Each circuit has five bifurcating parameters, one nonlinear element of cubic current–voltage characteristics, one controlled element, LCR components and a constant biasing source. The circuits can be considered as two coupled oscillators (linear and nonlinear) that form dual jerk circuits. Bifurcation diagrams of the circuits show a rather surprising result that the bifurcation patterns are of the Farey sequence structure and the circuits’ dynamics is of a fractal type. The circuits’ fractal dimensions of the box counting (capacity) algorithm, Kaplan–Yorke (Lyapunov) type and its modified (improved) version are all estimated to be between 2.26 and 2.52. Our analysis is based on numerical calculations which confirm a close relationship of the circuits’ bifurcation patterns with those of the Ford circles and Stern–Brocot trees. 相似文献
10.
Jan Blaszczak Jolanta Zimoch Wieslaw Hreczuch Aleksander Matuszewski Jan Szymanowski 《Journal of surfactants and detergents》1999,2(1):29-37
Surface and interfacial tension isotherms for narrow-range distribution ALFOL 1214 alcohol oxyethylates were determined and
compared with those obtained for broad-range alcohol oxyethylates. Various adsorption parameters were estimated. The effectiveness
of surface tension reduction decreases when the length of polyoxyethylene hydrophile increases. Micellization is observed
at log cmc ranging from −4.7 to −3.3. Effects of the length and distribution of the polyoxyethylene chain on cmc are very
small. A minimum of A
min/N
av
0.5 is obtained for N
av=8, where A
min and N
av denote the minimum interfacial area occupied by a statistical molecule at the saturated interface and the average degree
of oxyethylation, respectively. The interface becomes saturated at pC
20=−5.61±0.35, where pC
20 denotes the logarithm of concentration required to obtain the surface pressure equal to 20 mNm−1. The highest and lowest values of the surface excess at saturation and the free energy of adsorption, respectively, are obtained
for an average degree of oxyethylation equal to 8. Parameters are correlated with the average degree of oxyethylation and
the oxyethylene chain distribution parameter according to empirical second-order polynomials. Small differences in adsorption
abilities at the water/air interface are only observed for narrow- and broad-range distributed oxyethylates. The differences
become important for adsorption at the hexadecane/water interface. The lowest values of interfacial tension are obtained for
narrow-range oxyethylates with N
av=7 and 8. The Krefeld fabric detergency tests indicated that the best detergency was observed for alcohol oxyethylates with
N
av=5–7. Narrow-range oxyethylates exhibit somewhat better washing abilities than the broad-range products. No relationship between
detergency of alcohol oxyethylates and their abilities to adsorb at the water/air and water/hydrocarbon interfaces is observed. 相似文献