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排序方式: 共有347条查询结果,搜索用时 250 毫秒
321.
Markku Tamminen 《BIT Numerical Mathematics》1981,21(4):419-435
A data model for the analysis of worst and expected case performance of order preserving address calculation type data structures is presented. This model is used to derive results on the storage costs ofm-arytrie structures. The binary trie structure (EXHASH) is shown to be optimal in many ways. Under quite general conditions the expected performance of bucket tries for generalized priority queue access operations is shown to be asymptotically optimal, i.e.O(1). 相似文献
322.
Laure Fauch Ervin Nippolainen Alexei A. Kamshilin Markku Hauta-Kasari Jussi Parkkinen Timo Jääskeläinen 《Optical Review》2007,14(4):243-245
Accurate color classification by vector subspace method was implemented by simple optical system including computer controlled
set of light-emitting diodes and a photo-receiver operating in the integration regime. The technique is capable for fast and
precise classification of color distribution within two-dimensional frame with high spatial resolution. The feasibility of
the proposed system is shown by a test of four metameric colors, which were correctly distinguished. 相似文献
323.
Component Value Calculations and Characterizations for Measurements in the IEEE 1149.4 Environment 总被引:1,自引:1,他引:0
This paper describes a measurement principle for calculating component values from measurements conducted under less than
optimal conditions, as is the case in the IEEE Std 1149.4 environment. Also presented are equations that take into account
switch resistances on the signal paths, the output resistance of the signal generator, and the loading effect caused by the
input impedance of the voltmeter together with the pin capacitances in parallel to the voltmeter. In addition, the paper presents
characterization methods to determine values for these impedances. The inaccuracies achieved in the impedance range from kΩ
to MΩ are of the order of few percent.
相似文献
Markku MoilanenEmail: |
324.
Moilanen DE Levinger NE Spry DB Fayer MD 《Journal of the American Chemical Society》2007,129(46):14311-14318
The dynamics of water confined in two different types of reverse micelles are studied using ultrafast infrared pump-probe spectroscopy of the hydroxyl OD stretch of HOD in H2O. Reverse micelles of the surfactant Aerosol-OT (ionic head group) in isooctane and the surfactant Igepal CO 520 (nonionic head group) in 50/50 wt % cyclohexane/hexane are prepared to have the same diameter water nanopools. Measurements of the IR spectra and vibrational lifetimes show that the identity of the surfactant head groups affects the local environment experienced by the water molecules inside the reverse micelles. The orientational dynamics (time-dependent anisotropy), which is a measure of the hydrogen bond network rearrangement, are very similar for the confined water in the two types of reverse micelles. The results demonstrate that confinement by an interface to form a nanoscopic water pool is a primary factor governing the dynamics of nanoscopic water rather than the presence of charged groups at the interface. 相似文献
325.
Määttänen A Vehkamäki H Lauri A Napari I Kulmala M 《The Journal of chemical physics》2007,127(13):134710
We develop a two-component heterogeneous nucleation model that includes exact calculation of the Stauffer-type [D. Stauffer, J. Aerosol Sci. 7, 319 (1976)] steady-state kinetic prefactor using the correct heterogeneous Zeldovich factor for a heterogeneous two-component system. The model, and a simplified version of it, is tested by comparing its predictions to experimental data for water-n-propanol nucleating on silver particles. The model is then applied to water-carbon dioxide system in Martian conditions, which has not been modeled before. Using the ideal mixture assumption, the model shows theoretical possibilities for two-component nucleation adjacent to the initial stages of one-component water nucleation, especially with small water vapor amounts. The numbers of carbon dioxide molecules in the critical cluster are small in the case of large water amounts (up to 300 ppm) in the gas phase, but larger when there is very little water vapor (1 ppm). 相似文献
326.
We calibrate the methodology for the calculation of nuclear magnetic resonance (NMR) properties in novel organo-xenon compounds. The available state-of-the-art quantum-chemical approaches are combined and applied to the HXeCCH molecule as the model system. The studied properties are (129)Xe, (1)H, and (13)C chemical shifts and shielding anisotropies, as well as (131)Xe and (2)H nuclear quadrupole coupling constants. The aim is to obtain, as accurately as currently possible, converged results with respect to the basis set, electron correlation, and relativistic effects, including the coupling of relativity and correlation. This is done, on one hand, by nonrelativistic correlated ab initio calculations up to the CCSD(T) level and, on the other hand, for chemical shifts and shielding anisotropies by the leading-order relativistic Breit-Pauli perturbation theory (BPPT) with correlated ab initio and density-functional theory (DFT) reference states. BPPT at the uncorrelated Hartree-Fock level as well as the corresponding fully relativistic Dirac-Hartree-Fock method are found to be inapplicable due to a dramatic overestimation of relativistic effects, implying the influence of triplet instability in this multiply bonded system. In contrast, the fully relativistic second-order Moller-Plesset perturbation theory method can be applied for the quadrupole coupling, which is a ground-state electric property. The performance of DFT with various exchange-correlation functionals is found to be inadequate for the nonrelativistic shifts and shielding anisotropies as compared to the CCSD(T) results. The relativistic BPPT corrections to these quantities can, however, be reasonably predicted by DFT, due to the improved triplet excitation spectrum as compared to the Hartree-Fock method, as well as error cancellation within the five main BPPT contributions. We establish three computationally feasible models with characteristic error margins for future calculations of larger organo-xenon compounds to guide forthcoming experimental NMR efforts. The predicted (129)Xe chemical shift in HXeCCH is in a novel range for this nucleus, between weakly bonded or solvated atomic xenon and xenon in the hitherto characterized molecules. 相似文献
327.
328.
Masud Chaichian Markku Oksanen Anca Tureanu 《The European Physical Journal C - Particles and Fields》2011,71(6):1657
We study the recently proposed Covariant Renormalizable Gravity (CRG), which aims to provide a generally covariant ultraviolet
completion of general relativity. We obtain a spacetime decomposed form—an Arnowitt–Deser–Misner (ADM) representation—of the
CRG action. The action is found to contain time derivatives of the gravitational fields up to fourth order. Some ways to reduce
the order of these time derivatives are considered. The resulting action is analyzed using the Hamiltonian formalism, which
was originally adapted for constrained theories by Dirac. It is shown that the theory has a consistent set of constraints.
It is, however, found that the theory exhibits four propagating physical degrees of freedom. This is one degree of freedom
more than in Hořava–Lifshitz (HL) gravity and two more propagating modes than in general relativity. One extra physical degree
of freedom has its origin in the higher order nature of the CRG action. The other extra propagating mode is a consequence
of a projectability condition similarly as in HL gravity. Some additional gauge symmetry may need to be introduced in order
to get rid of the extra gravitational degrees of freedom. 相似文献
329.
Guillon G Zanchet A Leino M Viel A Zillich RE 《The journal of physical chemistry. A》2011,115(25):6918-6926
An analytical potential energy surface for a rigid Rb? in the 3Σ(u)? state interacting with one helium atom based on accurate ab initio computations is proposed. This 2-dimensional potential is used, together with the pair approximation approach, to investigate Rb? attached to small helium clusters He(N) with N = 1-6, 12, and 20 by means of quantum Monte Carlo studies. The limit of large clusters is approximated by a flat helium surface. The relative orientation of the dialkali axis and the helium surface is found to be parallel. Dynamical investigations of the pendular and of the in-plane rotation of the rigid Rb? molecule on the surface are presented. 相似文献
330.
A simple method for absolute-frequency measurements of molecular transitions in the mid-IR region is reported. The method is based on a cw singly resonant optical parametric oscillator (SRO), which is tunable from 3.2 to 3.45?μm. The mid-IR frequency of the SRO is referenced to an optical frequency comb through its pump and signal beams. Sub-Doppler spectroscopy and absolute-frequency measurement of the P(7) transition of the ν3 band of CH4 are demonstrated. 相似文献