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排序方式: 共有496条查询结果,搜索用时 62 毫秒
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2.
Varamesh Amir Prathapan Ragesh Telmadarreie Ali Li Jia Gourlay Keith Minhas Gurminder Lu Qingye Bryant Steven L. Hu Jinguang 《Cellulose (London, England)》2022,29(2):985-1001
Cellulose - There has been significant interest over recent years in the production and application of sustainable and green materials. Among these, nanocellulose has incurred great interest... 相似文献
3.
Summary Here we study impact-initiated disturbances in fluid-filled elastic tubes. The undeformed tube diameter, wall thickness, and elastic modulus of the tube material are assumed to be functions of the distance along the centre line of the tube. The linearized version of the governing equations are solved by the Laplace transform, which is inverted by means of an approximate method. The original non-linear system of governing equations is solved numerically by the method of characteristics. Relationships between the axial fluid velocity and axial coordinate as well as between velocity and time are displayed for fixed values of time and axial coordinate respectively for the linear and nonlinear theory for ease of comparison.
相似文献
Sommario Si studiano le perturbazioni prodotte da impatto in tubi elastici riempiti di fluidi. Si assume che il diametro del tubo indeformato, lo spessore della parete e il modulo elastico del materiale del tubo siano funzioni della distanza misurata lungo la linea centrale del tubo. La versione linearizzata delle equazioni che governano il fenomeno è risolta con la trasformata di Laplace, invertita con un metodo approssimato. Il sistema originale non lineare delle equazioni è risolto numericamente con il metodo delle caratteristiche. Vengono rappresentate, per valori fissati del tempo e della coordinata assiale, le relazioni tra la velocità assiale del fluido e la coordinata assiale oltre alle relazioni fra velocità e tempo, sia per la teoria lineare sia per quella non lineare.
相似文献
4.
A. E. Legzdins B. E. McCarry C. H. Marvin D. W. Bryant 《International journal of environmental analytical chemistry》2013,93(2-4):79-94
Abstract A normal phase HPLC methodology using a semi-preparative polyaminocyano column in conjunction with a selection of short-term genotoxicity assays has been developed for bioassay-directed fractionation studies of complex environmental mixtures. To illustrate the effectiveness of this methodology, an organic extract prepared from respirable air particulate samples collected in Hamilton, Canada was separated into a non-polar aromatic fraction and a polar aromatic fraction using a combination of alumina and Sephadex LH20 chromatography. These fractions were evaluated for their genotoxic potential using the Salmonella/microsome (Ames) assay with six different strains of Salmonella. The non-polar aromatic fraction was analyzed by normal phase HPLC and the eluent was collected in one-minute subfractions; these subtractions were bioassayed in three different Salmonella strains (YG1021 -S9, YG1024 -S9 and YG1029 +S9) to afford three different mutation profiles of this sample. Some subfractions which exhibited high mutagenic responses were subjected to further chemical analyses using GC/MS in order to identify those compounds responsible for the genotoxic responses. The nitroarene compounds 2-nitrofluoranthene, 1-nitropyrene and 2-nitropyrene and higher molecular weight polycyclic aromatic hydrocarbons such as benzo[a]pyrene and indeno[l,2,3-cd]pyrene were identified and quantified in some of the biologically active subfractions. The normal phase gradient conditions afforded very reproducible retention times for a series of polycyclic aromatic standards with a broad range of compound polarities. In addition, polycyclic aromatic hydrocarbons (PAH) were observed to elute from the normal phase HPLC column in a series of peaks; successive peaks contained PAH of increasing molecular weight while any individual peak was shown to contain PAH of the same molecular weight. 相似文献
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Rodney A. Bryant 《Proceedings of the Combustion Institute》2011,33(2):2481-2487
Stereoscopic particle image velocimetry (SPIV) was applied to a fire-induced doorway flow to provide the velocity field for computations of the mass flow rate of air into an enclosure. For a flow of uniform temperature and concentration, the technique met all of the requirements to provide the best estimate of the mass flow rate. Simultaneous measurements of vertical distributions of velocity and temperature were also conducted with conventional vent flow techniques, bi-directional probes and thermocouples. Correction factors for mass flow rate computations using the conventional techniques were determined based on comparisons to the SPIV results. An average correction factor of unity was determined for the bi-directional probe technique thus further confirming the utilization of velocity distributions acquired using the technique in mass flow rate computations. An average correction factor of 0.69 was determined for mass flow rates computed from vertical temperature distributions inside and outside the enclosure. This agrees with average correction factors determined in previous studies. The results from the present study suggest that the conventional techniques, which are practical and affordable for routine fire testing, may be applied with greater confidence for fires up to 500 kW. 相似文献
8.
For thin shells of revolution the existence of torsional-vibration modes, uncoupled from bending and extensional modes, has been established[1]. Here a linear second-order differential equation for the uncoupled torsional stress mode is obtained and its solution for impact loading of shells is sought. The mode-superposition method which utilizes the natural modes of vibration predicted by elementary theory, is, in general, not satisfactory for sharp impact loading as many modes are often required for convergence. Hence we employ two novel techniques for solving the impact problems. Firstly a formal asymptotic procedure, based on extensions to geometrical optics, is employed to generate asymptotic wavefront expansions. Rigorous justifications for this formal technique are provided in an appendix. Secondly a transform technique whereby solutions are sought in terms of Bessel functions is discussed and applied to particular impact loading problems. The Bessel function solutions found here can be used to determine the natural frequencies of the shells. Shells both finite and infinite in extent are discussed and reflections at a stress-free end are examined. 相似文献
9.
Acetone laser induced fluorescence for low pressure/low temperature flow visualization 总被引:1,自引:0,他引:1
Acetone fluorescence provides a useful way to visualize the fluid mixing process within supersonic wind tunnels, some of
which operate in the low temperature (240–300 K) and low pressure range (0.1–1 atm). Measurements are presented to quantify
the dependence of the acetone laser induced fluorescence (LIF) signal on temperature and pressure in this range. The temperature
and pressure sensitivity of the acetone LIF signal resulted in less than an 8% variation over the experimental conditions
for a laser excitation wavelength of 266 nm. Condensation of the acetone vapor was identified as a potential problem for this
diagnostic technique. Methods to prevent and check for condensation are discussed.
Received: 5 October 1998/Accepted: 10 April 1999 相似文献
10.
Darryn E. Bryant Saad El-Zanati Charles Vanden Eynden Dean G. Hoffman 《Graphs and Combinatorics》2001,17(1):55-59
Let S
k
denote the complete bipartite graph K
1,
k
and let Q
n
denote the n-cube. We prove that the obvious necessary conditions for the existence of an S
k
-decomposition of Q
n
are sufficient.
Received: July 21, 1999 Final version received: May 16, 2000 相似文献