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21.
Bennett N. Walker Jessica A. Stolee Deanna L. Pickel Scott T. Retterer Akos Vertes 《Applied Physics A: Materials Science & Processing》2010,101(3):539-544
Experimental assessment of the thermal load induced by fast laser pulses on micro- and nanostructures through IR imaging is
currently too slow and lacks the spatial resolution to be useful. In this paper, we introduce a method based on measuring
the laser-induced yields of ions to compare the thermal loads on nanofabricated silicon structures, when exposed to nanosecond
laser pulses. The laser fluences at which the ion yields of, for example, sodiated and potassiated peptides ions are equal
for two different structures correspond to equivalent thermal loads. Using alkalinated peptides is a convenient choice because
the corresponding ion intensities are easily measured up to the melting point of silicon. As an example, we compare the nanosecond
laser heating of silicon nanopost arrays with diverse post diameters and periodicities. Assessment of the thermal load through
ion yield measurements can also be used to verify model assumptions for heat transport regimes in nanostructures. 相似文献
22.
In a recent paper, a “distance” function,
, was defined which measures the distance between pure classical and quantum systems. In this work, we present a new definition of a “distance”, D, which measures the distance between either pure or impure classical and quantum states. We also compare the new distance formula with the previous formula, when the latter is applicable. To illustrate these distances, we have used 2 × 2 matrix examples and two-dimensional vectors for simplicity and clarity. Several specific examples are calculated. 相似文献
23.
Gerritz SW Norman MH Barger LA Berman J Bigham EC Bishop MJ Drewry DH Garrison DT Heyer D Hodson SJ Kakel JA Linn JA Marron BE Nanthakumar SS Navas FJ 《Journal of combinatorial chemistry》2003,5(2):110-117
The high-throughput manual solid-phase parallel synthesis of libraries comprising thousands of discrete samples using pellicular supports (i.e. SynPhase crowns and lanterns) and a suite of novel tools and techniques is described. Key aspects of this approach include the combination of a split-split-split synthesis strategy with spatial encoding to differentiate thousands of crowns, the rapid washing and filtration of up to 48 reaction vessels in parallel, the application of an inexpensive and environmentally friendly technique to remove trifluoroacetic acid from sixteen 96-well plates in parallel, and a high-throughput method for removing cleaved crowns from reusable pin racks. Tens of thousands of discrete samples have been produced in-house using this conceptually and operationally straightforward strategy. 相似文献
24.
This work presents a method for using nanosecond repetitively pulsed (NRP) plasma discharges for accelerating a propagating flame such that the deflagration-to-detonation transition occurs. A strategy is developed for bringing the location of the plasma near the tube wall and, thus, reducing the presence of the electrodes in the combustion tube as well as presenting a configuration in which cooling of the electrodes is viable for practical applications. Time-of-flight measurements were used in combination with energy deposition measurements and high-speed OH*-chemiluminescence imagery to investigate the flame acceleration process. For stoichiometric hydrogen–air flames, successful transition to detonation was achieved by applying a burst of 110 pulses at 100 kHz, with energies as low as 10 mJ per pulse. This was also achieved when plasma discharges were applied in the vicinity of the wall. Two enhancement mechanisms for flame acceleration were identified. The essential role of shock–flame interaction was established as being the main mechanism for flame acceleration when the discharges are located near the wall. This work presents an effective alternative that allows for NRP discharges to be applied near the wall while successfully maintaining a promising success rate for detonation transition. 相似文献
25.
Noah J. Tremblay Alon A. Gorodetsky Dr. Marshall P. Cox Theanne Schiros Dr. Bumjung Kim Rachel Steiner Zachary Bullard Aaron Sattler Woo‐Young So Dr. Yoshimitsu Itoh Dr. Michael F. Toney Dr. Hirohito Ogasawara Dr. Arthur P. Ramirez Prof. Ioannis Kymissis Dr. Michael L. Steigerwald Dr. Colin Nuckolls Prof. 《Chemphyschem》2010,11(4):742-742
26.
The Kaczmarz method is an algorithm for finding the solution to an overdetermined consistent system of linear equations Ax = b by iteratively projecting onto the solution spaces. The randomized version put forth by Strohmer and Vershynin yields provably
exponential convergence in expectation, which for highly overdetermined systems even outperforms the conjugate gradient method.
In this article we present a modified version of the randomized Kaczmarz method which at each iteration selects the optimal
projection from a randomly chosen set, which in most cases significantly improves the convergence rate. We utilize a Johnson–Lindenstrauss
dimension reduction technique to keep the runtime on the same order as the original randomized version, adding only extra
preprocessing time. We present a series of empirical studies which demonstrate the remarkable acceleration in convergence
to the solution using this modified approach. 相似文献
27.
28.
Cold production is a non-thermal process in which sand is intentionally produced with the oil in order to enhance oil recovery. Two experiments were performed to investigate the effect of producing large quantities of sand on the overall permeability of a formation. A large high porosity channel (wormhole) was observed in both experiments. A model of wormhole growth was successfully tested in two sand production experiments simulating the growth of a wormhole from a perforation in a vertical well. The produced volumes of oil, sand and gas, the pressure distribution along the pack and the final length of the wormholes were well predicted. The two sand packs had significantly different cohesive strengths. The strength of the sand did not have a significant effect on the growth of the wormholes. The formation of tensile failure bands at the wormhole surface, as observed in the experiments, may weaken the sand and allow it to be fluidized more easily. This weakening effect would explain the lower pressure gradients calculated at the surface of the wormhole while it developed compared to the critical pressure gradient for sand production predicted by Bratli and Risnes (1981). 相似文献
29.
Tremblay JC 《The Journal of chemical physics》2011,134(17):174111
In the present work, ideas for controlling photochemical reactions in dissipative environments using shaped laser pulses are presented. New time-local control algorithms for the stochastic Schro?dinger equation are introduced and compared to their reduced density matrix analog. The numerical schemes rely on time-dependent targets for guiding the reaction along a preferred path. The methods are tested on the vibrational control of adsorbates at metallic surfaces and on the ultrafast electron dynamics in a strong dissipative medium. The selective excitation of the specific states is achieved with improved yield when using the new algorithms. Both methods exhibit similar convergence behavior and results compare well with those obtained using local optimal control for the reduced density matrix. The favorable scaling of the methods allows to tackle larger systems and to control photochemical reactions in dissipative media of molecules with many more degrees of freedom. 相似文献
30.
Vladislav V. Kravchenko Sébastien Tremblay 《Mathematical Methods in the Applied Sciences》2011,34(16):1999-2010
Biquaternionic Vekua‐type equations arising from the factorization of linear second order elliptic operators are studied. Some concepts from classical pseudoanalytic function theory are generalized onto the considered spatial case. The derivative and antiderivative of a spatial pseudoanalytic function are introduced and their applications to the second order elliptic equations are considered. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献