An effective scaling frequency factor method for harmonic vibrational frequencies: The factors’ transferability problem

An effective scaling frequency factor method for scaling of harmonic vibrational frequencies: theory and preliminary application to toluene

An effective scaling frequency factor method for scaling of harmonic vibrational frequencies: The use of redundant primitive coordinates

Optimized scale factors for calculating vibrational harmonic and fundamental frequencies and zero-point energies have been determined for 145 electronic model chemistries, including 119 based on approximate functionals depending on occupied orbitals, 19 based on single-level wave function theory, three based on the neglect-of-diatomic-differential-overlap, two based on doubly hybrid density functional theory, and two based on multicoefficient correlation methods. Forty of the scale factors are obtained from large databases, which are also used to derive two universal scale factor ratios that can be used to interconvert between scale factors optimized for various properties, enabling the derivation of three key scale factors at the effort of optimizing only one of them. A reduced scale factor optimization model is formulated in order to further reduce the cost of optimizing scale factors, and the reduced model is illustrated by using it to obtain 105 additional scale factors. Using root-mean-square errors from the values in the large databases, we find that scaling reduces errors in zero-point energies by a factor of 2.3 and errors in fundamental vibrational frequencies by a factor of 3.0, but it reduces errors in harmonic vibrational frequencies by only a factor of 1.3. It is shown that, upon scaling, the balanced multicoefficient correlation method based on coupled cluster theory with single and double excitations (BMC-CCSD) can lead to very accurate predictions of vibrational frequencies. With a polarized, minimally augmented basis set, the density functionals with zero-point energy scale factors closest to unity are MPWLYP1M (1.009), τHCTHhyb (0.989), BB95 (1.012), BLYP (1.013), BP86 (1.014), B3LYP (0.986), MPW3LYP (0.986), and VSXC (0.986).

A Bayesian framework to update scaling factors for radioactive waste characterization

Study of the nuclide inventory of operational radioactive waste for the RBMK-1500 reactor

A least-squares approach has been used to determine multiplicative scaling factors for harmonic vibrational frequencies to facilitate comparison with experimentally observed frequencies. The harmonic frequencies were calculated using several of the most popular quantum chemical methods (HF, MP2, and B3LYP) and the correlation consistent family of basis sets (cc-pVxZ and aug-cc-pVxZ, where x = D(2), T(3), or Q(4)). Calculations were performed on 41 organic molecules for which fundamental frequencies are well established. When the derived scaling factors are applied, the percentage of calculated frequencies that deviate less than 3% from the experimental frequencies is 93−97% for B3LYP and 88−92% for MP2 when quadruple-ζ level basis sets are used. Similarly, scaling factors were determined for computing the vibrational components of the thermal contributions to enthalpy and entropy. An additional set of molecules was used in calculating scaling factors for the zero-point vibrational energy.

<p>Assessing progress towards greenhouse gas mitigation targets in recent legislation requires reliable, precise methods for emissions quantification.  Top-down approaches can provide a complementary assessment to the bottom-up inventories typically used by cities.</p><p>In this work we have performed a series of 9 winter aircraft measurement flights downwind of New York City in 2018 – 2020.  We use dispersion modeling driven by publicly available meteorological products to calculate footprints relevant to the flight data.  To calculate modeled emissions, we combine these footprints with four CO<sub>2</sub> inventories (ODIAC, EDGAR, ACES, and Vulcan) using a spatially explicit scaling factor approach.  We show that we can isolate the emissions from two areas of interest, New York City and the New York-Newark urban area, by using the fraction of modeled enhancements originating in said areas of interest as weighting functions.  We then calculate a scaling factor that optimizes agreement with measurements for each flight.  Here we discuss this technique and the posterior emissions for both areas of interest as compared to inversion analyses for the same areas.  We also quantify the variability across the ensemble including multiple meteorological products, scaling factor calculation methods, and mixing parameterizations across all inventories and flight days.</p>

Turbine blades are an important component of the turbine section of a gas turbine engine. High-temperature blade coating is a key technology for the manufacture of turbine engines, and its complex surface structure is currently lacking an effective non-destructive evaluation method for coating thickness. In this paper, the eddy current field is directly exciting in the substrate metal of the turbine blade coating system to achieve non-destructive detection of the coating thickness and substrate material. The results show that a new method of coating non-destructive testing based on the principle of array induction logging three-coil system is proposed. The shielding coil effectively cancels the direct coupling signal and enhances the signal from the coating and the substrate; when the distance between the transmitting coil and the main receiving coil is 8cm and the scale factor α is about 0.7047, the signal-to-noise ratio is increased by 102 times, and when the scale factor α is about 0.9032, the signal-to-noise ratio is increased by 215 times, the focusing effect is obvious while the scale factor α raises, and the sensitivity is also greatly improved; the receiving array is more than 4cm away from the transmitting coil, reflecting the more obvious change of coating thickness. When the distance between the transmitting coil and the main receiving coil is 4∼9cm, and the scale factor α is about 0.9032, the imaginary part of the measurement signal reflects the coating thickness changes more sensitively, and the real part of the measurement signal reflects substrate material changes more sensitively.

Internal radiation dose estimates for diagnostic nuclear medicine procedures are typically calculated for a reference individual. Resultantly, there is uncertainty when determining the organ doses to patients who are not at 50th percentile on either height or weight. This study aims to better personalize internal radiation dose estimates for individual patients by modifying the dose estimates calculated for reference individuals based on easily obtainable morphometric characteristics of the patient. Phantoms of different sitting heights and waist circumferences were constructed based on computational reference phantoms for the newborn, 10 year-old, and adult. Monoenergetic photons and electrons were then simulated separately at 15 energies. Photon and electron specific absorbed fractions (SAFs) were computed for the newly constructed non-reference phantoms and compared to SAFs previously generated for the age-matched reference phantoms. Differences in SAFs were correlated to changes in sitting height and waist circumference to develop scaling factors that could be applied to reference SAFs as morphometry corrections. A further set of arbitrary non-reference phantoms were then constructed and used in validation studies for the SAF scaling factors. Both photon and electron dose scaling methods were found to increase average accuracy when sitting height was used as the scaling parameter (~11%). Photon waist circumference-based scaling factors showed modest increases in average accuracy (~7%) for underweight individuals, but not for overweight individuals. Electron waist circumference-based scaling factors did not show increases in average accuracy. When sitting height and waist circumference scaling factors were combined, modest average gains in accuracy were observed for photons (~6%), but not for electrons. Both photon and electron absorbed doses are more reliably scaled using scaling factors computed in this study. They can be effectively scaled using sitting height alone as patient-specific morphometric parameter.

Selection and modification of ground motion records using a weighted scaling method based on the Newmark-Hall target spectrum

The plasma melting treatment of low level radioactive waste is currently in practical use. This treatment is applied to typical radioactive wastes such as carbon steel and concrete to produce a solidified product. The scaling factor method is used to evaluate the concentrations of radio-nuclides in the product. Because cobalt (Co) plays a particularly important role, it is important to clarify the behavior of Co during the treatment. In this report, we investigated the residual Co ratio in the slag produced during the plasma melting treatment of a nickel alloy. We found that a residual Co ratio of less than 10% was achieved in the slag when a Ni concentration of less than 80 wt% and a Fe concentration of more than 20 wt% was kept in the molten metal. The effect of the reduction of Co oxides by Fe on the residual Co ratio was the most dominant among the Co oxidation/reduction reactions occurring in the molten melt.

An optical study of N-(p-n-alkyloxybenzylidene)-p-n-butyloxyanilines, nO.O4 compounds with the alkoxy chain number n = 1, 3, 6, 7, and 10 has been carried out by measuring the refractive indices using modified spectrometer and direct measurement of birefringence employing the Newton's rings method. Further, the molecular polarizability anisotropies are evaluated using Lippincott δ-function model, the molecular vibration method, Haller's extrapolation method, and scaling factor method. The molecular polarizabilities α e and α 0 are calculated using Vuk's isotropic and Neugebauer anisotropic local field models. The order parameter S is estimated by employing the molecular polarizability values determined from experimental refractive indices and density data and the polarizability anisotropy values. Further, the order parameter S is also obtained directly from the birefringence data. A comparison has been carried out among the order parameter obtained from different ways and the results are compared with the body of the data available in the literature.

Although great progress has been made in modeling the gas fluidization of Geldart B and D particles and dilute gas−solid flow by standard Eulerian approach, researchers have shown that, because of the limitation of computational resources and the formation of subgrid-scale (SGS) heterogeneous structures, Eulerian model with a suitable SGS model for constitutive law is necessary to simulate the hydrodynamics of large-scale gas-fluidized beds containing Geldart A particles. In this article, a state-of-the-art review of Eulerian modeling of Geldart A particles in gas-fluidized beds is presented. The available methods for establishing SGS models are classified into six categories, that is, empirical correlation method, scaling factor method, structure-based method, modified Syamlal and O’Brien drag correlation method, EMMS-model-based method, and correlative multiscale method. The basic ideas of those methods, as well as their advant

SummaryLandscape‐ and community‐level CO2 measurements were made at a subarctic sedge fen near Churchill Manitoba during the 1997 growing season. Climatic conditions were warmer and drier than the 30‐y normal. Landscape‐scale micrometeorological measurements indicated that the wetland gained 49 g CO2 m−2 during the growing season. Chamber‐scale measurements from the main vegetation community types showed that small hummocks (Carex spp. sites) dominated the CO2 exchange, yielding an effective scaling factor of 70%. Scaled parameters of two algorithms describing photosynthesis and respiration for each community type show strong similarity to those derived at the landscape level. Scaling photosynthesis, respiration, and net ecosystem CO2 exchange from the community to landscape‐level over the season is within the maximum probable error of each methodological approach and helps substantiate the 1997 CO2 budget. We explore the equilibrium response of net ecosystem CO2 exchange of this fen to climatic change by examining the feedback of water table position on vegetation distribution and nitrogen availability. Based on the effective scaling factors computed for each community type, we hypothesize that a small decrease in mean water table position could nearly triple the net uptake of CO2 at this wetland.

Vibrational spectra of triamantane X 18H 24, iso-tetramantane X 22H 28 and cyclohexamantane X 26H 30 (X = C, Si, Ge, Sn) – A theoretical study