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排序方式: 共有774条查询结果,搜索用时 15 毫秒
1.
M. Kroon E. Andreasson E. Persson Jutemar V. Petersson L. Persson M. Dorn P.A.T. Olsson 《Experimental Mechanics》2018,58(1):75-86
Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters. 相似文献
2.
Dr. Karl P. J. Gustafson Arnar Guðmundsson Dr. Éva G. Bajnóczi Dr. Ning Yuan Prof. Xiaodong Zou Prof. Ingmar Persson Prof. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3411-3419
The activation process of a known Ru-catalyst, dicarbonyl(pentaphenylcyclopentadienyl)ruthenium chloride, has been studied in detail using time resolved in situ X-ray absorption spectroscopy. The data provide bond lengths of the species involved in the process as well as information about bond formation and bond breaking. On addition of potassium tert-butoxide, the catalyst is activated and an alkoxide complex is formed. The catalyst activation proceeds via a key acyl intermediate, which gives rise to a complete structural change in the coordination environment around the Ru atom. The rate of activation for the different catalysts was found to be highly dependent on the electronic properties of the cyclopentadienyl ligand. During catalytic racemization of 1-phenylethanol a fast-dynamic equilibrium was observed. 相似文献
3.
4.
We study the simultaneous one-dimensional flow of water and oil in a heterogeneous medium modelled by the Buckley-Leverett equation. It is shown both by analytical solutions and by numerical experiments that this hyperbolic model is unstable in the following sense: Perturbations in physical parameters in a tiny region of the reservoir may lead to a totally different picture of the flow. This means that simulation results obtained by solving the hyperbolic Buckley-Leverett equation may be unreliable.Symbols and Notation
f
fractional flow function varying withs andx
-
value off outsideI
-
value off insideI
-
local approximation off around¯x
-
f
–,f
+
values of
-
f
j
n
value off atS
j
n
andx
j
-
g
acceleration due to gravity [ms–2]
-
I
interval containing a low permeable rock
-
k
dimensionless absolute permeability
-
k
*
absolute permeability [m2]
-
k
c
*
characteristic absolute permeability [m2]
-
k
ro
relative oil permeability
-
k
rw
relative water permeability
-
L
*
characteristic length [m]
-
L
1
the space of absolutely integrable functions
-
L
the space of bounded functions
-
P
c
dimensionless capillary pressure function
-
P
c
*
capillary pressure function [Pa]
-
P
c
*
characteristic pressure [Pa]
-
S
similarity solution
-
S
j
n
numerical approximation tos(xj, tn)
-
S
1, S2,S
3
constant values ofs
-
s
water saturation
-
value ofs at
-
s
L
left state ofs (wrt.
)
-
s
R
right state ofs (wrt.
)
-
s
s for a fixed value of in Section 3
-
T
value oft
-
t
dimensionless time coordinate
-
t
*
time coordinate [s]
-
t
c
*
characteristic time [s]
-
t
n
temporal grid point,t
n=n t
-
v
*
total filtration (Darcy) velocity [ms–1]
-
W, , v
dimensionless numbers defined by Equations (4), (5) and (6)
-
x
dimensionless spatial coordinate [m]
-
x
*
spatial coordinate [m]
-
x
j
spatial grid piont,x
j=j x
-
discontinuity curve in (x, t) space
-
right limiting value of¯x
-
left limiting value of¯x
-
angle between flow direction and horizontal direction
- t
temporal grid spacing
- x
spatial grid spacing
-
length ofI
-
parameter measuring the capillary effects
-
argument ofS
-
o
dimensionless dynamic oil viscosity
- w
dimensionless dynamic water viscosity
-
c
*
characteristic viscosity [kg m–1s–1]
-
o
*
dynamic oil viscosity [kg m–1s–1]
-
w
*
dynamic water viscosity [k gm–1s–1]
-
o
dimensionless density of oil
-
w
dimensionless density of water
-
c
*
characteristic density [kgm–3]
-
o
*
density of oil [kgm–3]
-
w
*
density of water [kgm–3]
-
porosity
-
dimensionless diffusion function varying withs andx
-
*
dimensionless function varying with s andx
* [kg–1m3s]
-
j
n
value of atS
j
n
andx
j
This research has been supported by VISTA, a research cooperation between the Norwegian Academy of Science and Letters and Den norske stats oljeselskap a.s. (Statoil). 相似文献
5.
Peter Pöchlauer Christian Himmer Paul Peringer Ernst Peter Müller Thomas Jenny Walter Petter 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):455-458
Abstract Spirophosphoranes are produced by reaction of 2–phenyl–1,3,2–dioxaphospholane with both 2- and 3–hydroxycarboxylic acid azides, whereas 1–phenyl–phospholane yields spirophosphoranes only upon reaction with the former. The structures of two spirophosphoranes have been determined by X-ray analysis. 相似文献
6.
Marcus Malo Ronnie Persson Peder Svensson Kristina Luthman Lars Brive 《Journal of computer-aided molecular design》2013,27(3):277-291
Prediction of 3D structures of membrane proteins, and of G-protein coupled receptors (GPCRs) in particular, is motivated by their importance in biological systems and the difficulties associated with experimental structure determination. In the present study, a novel method for the prediction of 3D structures of the membrane-embedded region of helical membrane proteins is presented. A large pool of candidate models are produced by repacking of the helices of a homology model using Monte Carlo sampling in torsion space, followed by ranking based on their geometric and ligand-binding properties. The trajectory is directed by weak initial restraints to orient helices towards the original model to improve computation efficiency, and by a ligand to guide the receptor towards a chosen conformational state. The method was validated by construction of the β1 adrenergic receptor model in complex with (S)-cyanopindolol using bovine rhodopsin as template. In addition, models of the dopamine D2 receptor were produced with the selective and rigid agonist (R)-N-propylapomorphine ((R)-NPA) present. A second quality assessment was implemented by evaluating the results from docking of a library of 29 ligands with known activity, which further discriminated between receptor models. Agonist binding and recognition by the dopamine D2 receptor is interpreted using the 3D structure model resulting from the approach. This method has a potential for modeling of all types of helical transmembrane proteins for which a structural template with sequence homology sufficient for homology modeling is not available or is in an incorrect conformational state, but for which sufficient empirical information is accessible. 相似文献
7.
Hideyuki Tatsuno Kasper S. Kjr Kristjan Kunnus Tobias C. B. Harlang Cornelia Timm Meiyuan Guo Pavel Chbera Lisa A. Fredin Robert W. Hartsock Marco E. Reinhard Sergey Koroidov Lin Li Amy A. Cordones Olga Gordivska Om Prakash Yizhu Liu Mads G. Laursen Elisa Biasin Frederik B. Hansen Peter Vester Morten Christensen Kristoffer Haldrup Zoltn Nmeth Dorottya Srosin Szemes va Bajnczi Gyrgy Vank Tim B. Van Driel Roberto Alonso‐Mori James M. Glownia Silke Nelson Marcin Sikorski Henrik T. Lemke Dimosthenis Sokaras Sophie E. Canton Asmus O. Dohn Klaus B. Mller Martin M. Nielsen Kelly J. Gaffney Kenneth Wrnmark Villy Sundstrm Petter Persson Jens Uhlig 《Angewandte Chemie (International ed. in English)》2020,59(1):364-372
Iron N‐heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub‐ps X‐ray spectroscopy study of an FeIINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot 3MLCT state, from the initially excited 1MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the 3MC state, in competition with vibrational relaxation and cooling to the relaxed 3MLCT state. The relaxed 3MLCT state then decays much more slowly (7.6 ps) to the 3MC state. The 3MC state is rapidly (2.2 ps) deactivated to the ground state. The 5MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the 3MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition‐metal complexes for similar ultrafast decays to optimize photochemical performance. 相似文献
8.
9.
An oxidative chemical vapor deposition (OCVD) process was used to coat flexible textile fiber (viscose) with highly conductive polymer, poly (3,4‐ethylenedioxythiophene) (PEDOT) in presence of ferric (III) chloride (FeCl3) oxidant. OCVD is a solvent free process used to get uniform, thin, and highly conductive polymer layer on different substrates. In this paper, PEDOT coated viscose fibers, prepared under specific conditions, exhibited high conductivity 14.2 S/cm. The effects of polymerization conditions, such as polymerization time, oxidant concentration, dipping time of viscose fiber in oxidant solution, and drying time of oxidant treated viscose fiber, were carefully investigated. Scanning electron microscopy (SEM) and FT‐IR analysis revealed that polymerization of PEDOT on surface of viscose fiber has been taken place and structural analysis showed strong interactions between PEDOT and viscose fiber. Thermogravimetric analysis (TGA) was employed to investigate the amount of PEDOT in PEDOT coated viscose fiber and interaction of PEDOT with viscose fiber. The effect of PEDOT coating on the mechanical properties of the viscose fiber was evaluated by tensile strength testing of the coated fibers. The obtained PEDOT coated viscose fiber having high conductivity, could be used in smart clothing for medical and military applications, heat generation, and solar cell demonstrators. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
10.
Ernst Peter Müller Paul Peringer Roland Aeschimann Thomas Maetzke Walter Petter 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Reaction of the 2-azidoalcohol 1 with 2-phenyl1-1,3,2-dioxaphospholane leads to a 4:1 mixture of the pentacoordinate phosphorane 3 and the diazadiphosphetidine 4. In solution, these compounds are in equilibrium, presumably involving the not detectable iminophosphorane 2. A single X-ray analysis carried out on 3 proves the structure of this type of compound which has been postulated earlier as intermediate in the synthesis of aziridines from azidoalcohols1,2 相似文献