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排序方式: 共有138条查询结果,搜索用时 15 毫秒
11.
Niels van der Laan Ward Romeijnders Maarten H. van der Vlerk 《Computational Management Science》2018,15(3-4):325-349
We derive bounds on the expectation of a class of periodic functions using the total variations of higher-order derivatives of the underlying probability density function. These bounds are a strict improvement over those of Romeijnders et al. (Math Program 157:3–46, 2016b), and we use them to derive error bounds for convex approximations of simple integer recourse models. In fact, we obtain a hierarchy of error bounds that become tighter if the total variations of additional higher-order derivatives are taken into account. Moreover, each error bound decreases if these total variations become smaller. The improved bounds may be used to derive tighter error bounds for convex approximations of more general recourse models involving integer decision variables. 相似文献
12.
Hazra P Inoue K Laan W Hellingwerf KJ Terazima M 《The journal of physical chemistry. B》2008,112(5):1494-1501
A recently developed method for time-resolved thermodynamic measurements was used to study the photochemical reaction(s) of the BLUF domain of AppA (AppA-BLUF), which has a dimeric form in the ground state, in terms of the energetics and heat capacity changes (DeltaC(p)) in different time domains. The enthalpy change (DeltaH) of the first intermediate that forms within 1 ns after photoexcitation was 38 (+/-8) kJ mol(-1) at 298 K. The heat capacity change (DeltaC(p)) upon formation of this intermediate was positive [1.4 (+/-0.3) kJ mol(-1) K(-1)]. This positive DeltaC(p) suggests that the hydrophobic surface area of AppA-BLUF exposed to the bulk solvent increased. After this initial transition, a dimerization reaction with another ground-state dimer (i.e., tetramer formation) takes place. Upon this reaction, the energy was stabilized to 26 (+/-6) kJ mol(-1) at 298 K. Interestingly, the dimer formation was accompanied by a larger but negative DeltaC(p) [-6.0 (+/-1) kJ mol(-1) K(-1)]. This negative DeltaC(p) might indicate buried hydrophobic residues at the interface of the dimer and/or the existence of trapped water at the interface. We suggest that hydrophobic interactions are the main driving force for the formation of the dimer upon photoactivation of AppA-BLUF. 相似文献
13.
Ina Vollmer Michael J. F. Jenks Mark C. P. Roelands Robin J. White Toon van Harmelen Paul de Wild Gerard P. van der Laan Florian Meirer Jos T. F. Keurentjes Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2020,59(36):15402-15423
Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re‐extrusion. Various chemical recycling processes have great potential to enhance recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life‐cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy. 相似文献
14.
V. Repän M. Laan P. Paris J. Aarik V. Sammelselg 《Czechoslovak Journal of Physics》1999,49(2):217-224
In the paper the results of experimental study of negative corona in a point – plane gap in a dust-free air flow at atmospheric pressure are presented. Both the low current mode (LCM) of the discharge and Trichel pulses are externally triggered by UV light. Close to the inception voltage of Trichel pulses short-duration current spikes appear besides the steady component of the LCM which indicates to the switch-on of Fowler-Nordheim type emission mechanism. At the inception voltage spike – Trichel pulse transition is recorded. The influence of dielectric layers at the cathode on the discharge parameters is discussed. 相似文献
15.
In this paper, we consider the limiting paths of simplicial algorithms for finding a zero point. By rewriting the zero-point problem as a problem of finding a stationary point, the problem can be solved by generating a path of stationary points of the function restricted to an expanding convex, compact set. The limiting path of a simplicial algorithm to find a zero point is obtained by choosing this set in an appropriate way. Almost all simplicial algorithms fit in this framework. Using this framework, it can be shown very easily that Merrill's condition is sufficient for convergence of the algorithms. 相似文献
16.
A. Mirone S. S. Dhesi G. van der Laan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(1):23-28
Orbital ordering (OO) in La0.5Sr1.5MnO4 has been
studied using soft X-ray resonant diffraction (SXRD) at the Mn L2,3 edges
in combination with many-body cluster calculations. The SXRD intensity is modelled in second quantization using a
small planar cluster consisting of a central active Mn site with first-neighbour shells comprising O and Mn sites.
The effective Hamiltonian includes Slater-Koster parameters and charge transfer and electron correlation
energies obtained from previous measurements on manganites. The
energy dependence of the SXRD OO peak is calculated using
the Jahn-Teller distortions of the oxygen octahedra and in-plane spin correlations as adjustable parameters. These contributions
are clearly distinguished above the Néel temperature with a good spectroscopic agreement.
The results also suggest a significant charge separation between the Mn sites. 相似文献
17.
18.
N. Jaouen J.M. Tonnerre D. Raoux L. Ortega E. Bontempi M. Münzenberg W. Felsch M. Suzuki H. Maruyama H.A. Dürr E. Dudzik G. van der Laan 《Applied Physics A: Materials Science & Processing》2001,72(6):711-715
The element and electronic shell specificities of X-ray resonant magnetic scattering have been used to investigate the magnetization
of Ce 5d and Fe 3d states in [CeH2(19.6 ?)/Fe(25.4 ?)]*38 a multilayer. We show that the measurement of the magnetic contribution to the intensities reflected
at low angles at the Ce L2 and Fe L2,3 edges allows us to investigate the profile of the Ce 5d and Fe 3d magnetic polarization. The Fe 3d polarization is found
to be uniform across the Fe layer and the Ce 5d polarization appears to be restricted close to the interface with Fe.
Received: 22 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001 相似文献
19.
20.
Summary The equations of motion and the mechanical energy balances for two-phase flow systems are derived by integration over a volume containing a large number of elements of the dispersed phase.List of symbols
A, A
boundary of volumes V, V
- dA, dA
surface element of A, A
-
A
s
boundary of particles in V
- dA
s
surface element of A
s
-
F
force per unit volume of the system
-
g
–gz=gravity vector
-
g
acceleration by gravity
-
I
unit tensor
-
p
pressure
-
Q
dissipation in the continuous phase
-
Q
s
dissipation in the dispersed phase
-
R
compression work in the continuous phase
-
R
s
compression work in the dispersed phase
-
t
time
-
u
velocity of continuous phase
-
u
s
velocity of dispersed phase
-
u
magnitude of u
-
u
s
magnitude of u
s
-
V
volume in the two-phase system
-
V
part of V occupied by the continuous phase
-
W
work done by F
-
z
vertical coordinate
-
local volume fraction of the dispersed phase
-
pI–=stress tensor of the continuous phase
-
s
turbulent particle stress tensor
-
density of the continuous phase
-
s
density of the dispersed phase
-
shearing-stress tensor of the continuous phase
-
s
turbulent particle shearing-stress tensor
-
nabla operator
-
u, u
s
velocity gradient tensor
-
substantial derivative
(Shell Internationale Research Maatschappij N.V.)(Bataafse Internationale Petroleum Maatschappij N.V.) 相似文献