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251.
Turkka Salminen Mikko Hahtala Ilkka Sepp?l? Pekka Laukkanen Tapio Niemi 《Applied Physics A: Materials Science & Processing》2010,101(4):735-738
Thin films of yttria stabilized zirconia were deposited onto silicon substrates using high repetition rate picosecond pulse
lasers. The applied lasers covered the repetition rate range from 10 kHz to 4 MHz. We found that the laser pulse overlapping
which results from increased repetition rates led to considerable changes in the ablation process. Defect formation and local
heating lead to lower ablation thresholds and, with sufficiently high repetition rates, to melting of the target and even
to thermal evaporation. We found that yttria-stabilized zirconia (YSZ) films deposited with picosecond pulses at 1064 nm wavelength
below repetition rates of 2 MHz have rough, nanostructured morphology and the same atomic ratio of yttrium and zirconium as
the target. Films deposited with 2 MHz and higher repetition rates with high number of overlapping pulses are very smooth,
but are yttrium deficient, providing evidence of the importance of the thermal processes. 相似文献
252.
A contactless method of measuring the radiation pattern of a UHF RFID transponder is presented. The novel technique does not require any special transponder IC or measurement equipment. The measurement method also enables radiation pattern determination in the end-use application. The measurement setup and some example results are presented. 相似文献
253.
Genetic algorithms are commonly used metaheuristics for global optimization, but there has been very little research done
on the generation of their initial population. In this paper, we look for an answer to the question whether the initial population
plays a role in the performance of genetic algorithms and if so, how it should be generated. We show with a simple example
that initial populations may have an effect on the best objective function value found for several generations. Traditionally,
initial populations are generated using pseudo random numbers, but there are many alternative ways. We study the properties
of different point generators using four main criteria: the uniform coverage and the genetic diversity of the points as well
as the speed and the usability of the generator. We use the point generators to generate initial populations for a genetic
algorithm and study what effects the uniform coverage and the genetic diversity have on the convergence and on the final objective
function values. For our tests, we have selected one pseudo and one quasi random sequence generator and two spatial point
processes: simple sequential inhibition process and nonaligned systematic sampling. In numerical experiments, we solve a set
of 52 continuous test functions from 16 different function families, and analyze and discuss the results. 相似文献
254.
We consider questions related to quantizing complex valued functions defined on a locally compact topological group. In the case of bounded functions, we generalize R. Werner's approach to prove the characterization of the associated normal covariant quantization maps. 相似文献
255.
We consider a telecommunication problem in which the objective is to schedule data transmission to be as fast and as cheap
as possible. The main characteristic and restriction in solving this multiobjective optimization problem is the very limited
computational capacity available. We describe a simple but efficient local search heuristic to solve this problem and provide
some encouraging numerical test results. They demonstrate that we can develop a computationally inexpensive heuristic without
sacrificing too much in the solution quality. 相似文献
256.
Development of Counting Skills: Role of Spontaneous Focusing on Numerosity and Subitizing-Based Enumeration 总被引:1,自引:0,他引:1
Children differ in how much they spontaneously pay attention to quantitative aspects of their natural environment. We studied how this spontaneous tendency to focus on numerosity (SFON) is related to subitizing-based enumeration and verbal and object counting skills. In this exploratory study, children were tested individually at the age of 4-5 years on these skills. Results showed 2 primary relationships in children's number skills development. Performance in a number sequence production task, which is closely related to ordinal number sequence without reference to cardinality, is directly associated with SFON. Second, the association of SFON and object counting skills, which require relating cardinal and ordinal aspects of number, is mediated by subitizing-based enumeration. This suggests that there are multiple pathways to enumeration skills during development. 相似文献
257.
Pekka Koskela 《Arkiv f?r Matematik》1999,37(2):291-304
We study removable sets for the Sobolev spaceW
1,p. We show that removability for sets lying in a hyperplane is essentially determined by their thickness measured in terms
of a concept ofp-porosity.
The author was partially supported by the NSF and the Academy of Finland, SA-34082. 相似文献
258.
We prove that quasiconformal maps onto domains which satisfy a suitable growth condition on the quasihyperbolic metric are
uniformly continuous when the source domain is equipped with the internal metric. The obtained modulus of continuity and the
growth assumption on the quasihyperbolic metric are shown to be essentially sharp. As a tool, we prove a new capacity estimate. 相似文献
259.
We introduce a new faster molecular dynamics (MD) engine into the CHARMM software package. The new MD engine is faster both in serial (i.e., single CPU core) and parallel execution. Serial performance is approximately two times higher than in the previous version of CHARMM. The newly programmed parallelization method allows the MD engine to parallelize up to hundreds of CPU cores. © 2013 Wiley Periodicals, Inc. 相似文献
260.
Structural and Photophysical Study on Heterobimetallic Complexes with d8–d10 Interactions Supported by Carborane Ligands: Theoretical Analysis of the Emissive Behaviour
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Dr. Olga Crespo Prof. M. Concepción Gimeno Prof. Antonio Laguna Dr. Olli Lehtonen Dr. Isaura Ospino Prof. Pekka Pyykkö Dr. M. Dolores Villacampa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3120-3127
Heterobimetallic complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M′(PPh3)] (M=Pd, Pt; M′=Au, Ag, Cu) and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] were obtained from the reaction of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (M=Pd, Pt) with [M′(PPh3)]+ (M′=Au, Ag, Cu) or by one‐pot synthesis from [(SH)2C2B10H10], (PPh2)2C2B10H10, NiCl2 ? 6 H2O, and [Au(PPh3)]+. They display d8–d10 intermetallic interactions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M=Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)‐to‐“P2‐M‐S2” (ML′) charge‐transfer (LML′CT) transitions for M=Pt and to metal (M)‐to‐“P2‐M‐S2” (ML′) charge‐transfer (MML′CT) transitions for M=Ni, Pd. 相似文献