Method Calculations Research Articles

Polaritonic Chemistry Using the Density Matrix Renormalization Group Method.

The emerging field of polaritonic chemistry explores the behavior of molecules under strong coupling with cavity modes. Despite recent developments in ab initio polaritonic methods for simulating polaritonic chemistry under electronic strong coupling, their capabilities are limited, especially in cases where the molecule also features strong electronic correlation. To bridge this gap, we have developed a novel method for cavity QED calculations utilizing the Density Matrix Renormalization Group (DMRG) algorithm in conjunction with the Pauli-Fierz Hamiltonian. Our approach is applied to investigate the effect of the cavity on the S0-S1 transition of n-oligoacenes, with n ranging from 2 to 5, encompassing 22 fully correlated π orbitals in the largest pentacene molecule. Our findings indicate that the influence of the cavity intensifies with larger acenes. Additionally, we demonstrate that, unlike the full determinantal representation, DMRG efficiently optimizes and eliminates excess photonic degrees of freedom, resulting in an asymptotically constant computational cost as the photonic basis increases.

Computational study of substituent effects on molecular structure, vibrational and electronic properties of fluorene molecule using density functional theory

Density functional theory (DFT) provides a powerful tool for investigating the effects of halogen (F, Cl and Br) substitution on the electronic and structural properties of fluorene. The B3LYP/6-31G (d,p) protocol is a commonly used method in DFT calculations for the optimisation of molecular structures and the calculation of various molecular properties by Gaussian 09 W program. In the case of the fluorene molecule with halogen substitutions, (TD–DFT) calculations can be used to predict its UV–Vis spectrum. The B3LYP density functional model with a 6-31G(d,p) basis set is a common choice for performing (TD–DFT) calculations on molecules. The results showed a decrease in gap energies when electron-withdrawing groups were present in the molecule. A decrease in the gap energy indicates that the molecule is less stable and more reactive.

Multidomain spectral method for self-force calculations

Multidomain spectral method for self-force calculations

Updating the no-history method in intraocular lens power calculation after myopic laser vision correction.

To describe the Shammas-Cooke formula, an updated no-history (NH) formula for IOL calculation in eyes with prior myopic laser vision correction (M-LVC), and to compare the results with the Shammas PL, Haigis-L, and Barrett True-K NH formulas. Bascom Palmer Eye Institute (BPEI), The Lennar Foundation Medical Center, University of Miami, Miami, Florida; Dean A. McGee Eye Institute (DMEI), University of Oklahoma, Oklahoma City, Oklahoma; and private practice, Lynwood, California, and St Joseph, Michigan. Retrospective observational study. We analyzed 2 large series of cataractous eyes with prior M-LVC. The training set (BPEI series of 330 eyes) was used to derive the new corneal power conversion equation to be used in the new Shammas-Cooke formula and the testing set (165 eyes of 165 patients in the DMEI series) to compare the updated formula with 3 other M-LVC NH formulas on the ASCRS calculator: Shammas PL, Haigis-L, and Barrett True-K NH. Mean prediction error was 0.09 ± 0.56 diopters (D), -0.44 ± 0.61 D, -0.47 ± 0.59 D, and -0.18 ± 0.56 D and the mean absolute error was 0.43 D, 0.60 D, 0.61 D, and 0.45 D for the Shammas-Cooke, Shammas PL, Haigis-L, and Barrett True-K NH, respectively. The percentage of eyes within ±0.50 D was 66.7% vs 47.9%, 48.5%, and 65.5%, respectively. The Shammas-Cooke formula performed better than the Shammas PL and Haigis-L (P < .001 for both) and as well as the Barrett True-K NH formula (P = .923).

Сравнительный анализ методов построения систем обработки зашифрованных данных и их сравнение для решения задач машинного обучения

The article discusses two methods for constructing encrypted data processing systems based on homomorphic encryption and separation calculations. Each method differs from each other in the presented algorithm and data processing model. Basic operations on encrypted data are considered, namely, multiplication and addition. The following libraries were used for the study: tenSEAL, tensorflow and PyTorch. The tenSEAL library is a fork of the full homomorphic encryption tool created for the C++ programming language, but adapted for the Python programming language used in the study. This library allows you to use the method of full homomorphic encryption in constructing a computational model, the task of which will be to process encrypted data. To implement the method of separation calculations, better known as multi-party computation, the tensorflow library will be used, which allows you to create several tensors and train them simultaneously, which in turn makes it possible to implement the principle of separation calculations.

Use of Constant Type Cost Prorate Method in Calculation of Actuarial Liability of Pension Funds

Use of Constant Type Cost Prorate Method in Calculation of Actuarial Liability of Pension Funds

Electron impact ionization in dense plasmas

The distorted-wave with exchange (DWE) method is employed to evaluate electron impact ionization cross sections in dense electron–ion plasmas. Bound and continuum electron wave functions are obtained from a non-relativistic average-atom code. Plots of DWE cross sections are presented for 1s electrons in Li and Be plasmas and 2p electrons in Na and Mg plasmas. For each of these elements, cross sections are evaluated at metallic density in a range of temperatures from 10 to 100 eV and at their respective melting points. Resonances in the cross sections appear near the incident energy threshold at high temperatures. The origin of these resonances is discussed. In general, the distorted wave (DW) method without exchange is found to be a good approximation to the DWE method for electron impact ionization calculations. In the resonance region, however, exchange effects are found to be very important and cannot be neglected.

Measuring ornamental tree canopy attributes for precision spraying using drone technology and self-supervised segmentation

Tree canopy attributes or characteristics, such as canopy volume and density, are important parameters for calculating the precise quantity of agrochemicals required in each tree. Assessing the agrochemical needs in a nursery can help growers effectively estimate expenses, mitigate the risks of overuse or underuse, enhance resource utilization, and promote sustainable agricultural practices. This study aimed to develop an unmanned aerial vehicle (UAV)-based system to measure tree canopy attributes like tree height, tree count, canopy area and canopy volume using an image processing and self-supervised zero-shot segmentation approach. A high-resolution red-green-blue (RGB) sensor mounted on a drone captured three aerial image datasets, D1 and D2 from the first experimental plot and D3 from the second experimental plot. The acquired aerial images were stitched together and processed to generate a digital surface model (DSM) and a digital terrain model (DTM). A self-supervised zero-shot segmentation model, Segment Anything Model (SAM), was applied for tree segmentation and counting. The tree canopy area was calculated by segmenting individual trees and applying a conversion factor to convert pixelwise areas into square meters. Height calculation was done using elevation data of each pixel from DSM-DTM imagery within SAM-derived bounding box coordinates, and the highest pixel was considered as the height of the tree. The drone-calculated heights of 24 randomly selected trees were compared with manually measured heights in all datasets. The results showed an average absolute error of 2.43% in D1, 7.09% in D2 and 12.58% in D3. The Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) were noted to be 0.09 m and 0.23 m in D1, 0.13 m and 0.25 m in D2, and 0.16 m and 0.21 m in D3, respectively. In D3, manual area and volume calculations were performed for validation. The RMSE and MAE for area calculation were calculated as 0.18 m2 and 0.15 m2, respectively, and the RMSE and MAE for volume measurements were calculated as 0.33 m3 and 0.26 m3 respectively, which indicated the level of agreement between manual and drone measurements. Using canopy volume information, calculated by summing pixel heights within each tree’s bounding box and multiplying by the ground sample distance (GSD) of 0.025 m per pixel, the average quantity of agrochemicals needed for a Maple tree was estimated at 0.20 L. These results underscore the high potential of this method for accurate canopy characteristic calculations and precision spray applications in the ornamental industry.

Efficient removal of nitrophenol by magnetic ion exchange resins: Role of nitrophenol functional groups based on characterisation, DFT calculations and site energy distributions

The diverse locations of functional groups on different nitrophenol cause uncertainty concerning the removal efficiency and mechanisms of nitrophenol. Adsorption behavior and mechanisms of nitrophenol pollutants (2-nitrophenol (ONP) and 4-nitrophenol (PNP)) on magnetic ion exchange (MIEX) resin were investigated by a combination method of characterization, DFT calculations, and site energy analysis. The results showed pore filling, hydrophobicity, hydrogen bonding, van der Waals forces, π-π conjugation, ion exchange, and electrostatic attraction were included in the removal mechanisms. Solution pH influenced the adsorption mechanism by inducing electrostatic attraction, hydrogen bonding and ion exchange. DFT calculations found that hydrogen bonding was the dominant action among the removal mechanisms for the nitrophenol existing in the form of a molecular state. But distinguished from the removal of PNP by the interaction of hydrogen bonds (O⋯H-N) between the –NO2 in PNP and the –NH-CO– group in MIEX resin, the ONP was mainly removed by hydrogen bonds (H⋯O-C) between the –OH functional group in ONP and the –COOH functional group in MIEX resin. However, the ionic nitrophenol pollutants were mainly removed through electrostatic attraction and ion exchange. Increasing resin dosage facilitated the removal of nitrophenol. Humic acid demonstrated little effect. Sulfate ions showed the most severe inhibition on the removal of nitrophenol. Equilibrium was achieved after 60 min. The adsorption process was well described using the Sips isotherm. The main rate-limiting step was liquid film diffusion. Site energy analysis found that the affinity of PNP for MIEX resin was higher, and the removal of PNP was more susceptible to temperature compared to ONP. A 1.0 % sodium chloride could effectively regenerate the saturated resin, and the adsorption efficacy did not decrease significantly after four adsorption–desorption cycles. Therefore, MIEX resin has a good potential for the control of nitrophenol in polluted water sources.

Exocomet Models in Transit: Light Curve Morphology in the Optical—Near Infrared Wavelength Range

Following the widespread practice of exoplanetary transit simulations, various presumed components of an extrasolar system can be examined in numerically simulated transits, including exomoons, rings around planets, and the deformation of exoplanets. Template signals can then be used to efficiently search for light curve features that mark specific phenomena in the data, and they also provide a basis for feasibility studies of instruments and search programs. In this paper, we present a method for exocomet transit light curve calculations using arbitrary dust distributions in transit. The calculations, spanning four distinct materials (carbon, graphite, pyroxene, and olivine), and multiple dust grain sizes (100–300 nm, 300–1000 nm, and 1000–3000 nm) encompass light curves in VRJHKL bands. We also investigated the behavior of scattering colors. We show that multicolor photometric observations are highly effective tools in the detection and characterization of exocomet transits. They provide information on the dust distribution of the comet (encoded in the light curve shape), while the color information itself can reveal the particle size change and material composition of the transiting material, in relation to the surrounding environment. We also show that the typical cometary tail can result in the wavelength dependence of the transit timing. We demonstrate that multi-wavelength observations can yield compelling evidence for the presence of exocomets in real observations.

PROPER NAMES OF THE SEAS: STRUCTURE, ORIGIN, FUNCTIONING IN UKRAINIAN LANGUAGE

The main goal of our research is to collect, systematize and analyze the proper names of all seas that are in the Ukrainian language. The purpose of the research involves solving the following tasks: 1) to draw up a register of pelagonyms; 2) determine their denotative and characteristic features; 3) find out etymological and word-forming features; 4) describe the peculiarities of functioning in the Ukrainian language; 5) establish the defining features of this type of proper names. The object of analysis is 238 pelagonyms, and their denotative-characteristic, etymological-word-forming and functional features are the subject of analysis. In the process of analysis, we used genetic (to determine the origin of proper names), etymological (to find out the features of names creation), descriptive (to determine the extralingual features of pelagonyms), structural (to characterize the structure of names), functional (to describe features related to the functioning of seas names in texts of various styles) research methods and the method of quantitative calculations (to determine the productivity of different types of pelagonyms). It was established that compound constructions (the most productive models are "noun + adjective" and "noun + noun"), formed by a syntactic method, with combined motivation (in particular, locative-, memorial-, and qualitative-substantial) dominate, they are derived from onyms and appellatives. Geographical terms and anthroponyms or toponyms prevail in their composition. Most pelagonyms are ancient, hybrid, lowfrequency, emotionally neutral names that have a known and obscure etymology, are used in a scientific style, are elements of language (not speech), belong to the passive vocabulary, are unknown to the general public, and are devoid of ethnocultural meaning. In the future, we plan to pay attention to the general characteristics of other proper names: both open water bodies (for example, loughs or streams), and such categories as oikonyms, oronyms, or choronyms. Over time, this will make it possible to form a complete picture of the Ukrainian toponymy.

A novel simplified simulation method for the precooler based on the virtual source term: modeling, validation and application

Precooling technology is one of the promising approaches for expanding the flight envelope of conventional turbine engines and enhancing flight performance at high Mach numbers. Within this domain, a crucial challenge is to rapidly and accurately obtain the flow and heat transfer characteristics of the precooler. Currently, full-size simulation of the precooler is impractical, while simplified and fast simulation methods employed in previous research have exhibited certain deficiencies, including excessive simplification and unconvincing validation. In this study, a novel simplified simulation method for the annular precooler based on the virtual source term model was proposed. This method comprehensively considered the axial and radial non-uniformity of airflow caused by the coupling effect between the precooler and the inlet channel in the actual flow field. Subsequently, systematic validations of the reliability and superiority of this method were conducted, along with its application in the overall performance calculation of the precooled engine. The results demonstrate that the simplified method proposed in this paper showcases higher accuracy than the methods employed in previous research. Compared with the real model, the relative errors of the overall parameters are within ± 1 %, and the relative errors of the distortion indices for total temperature and total pressure are 5.1 % and −1.5 %, respectively. Meanwhile, the number of computational mesh cells is reduced by more than 95 %. Moreover, the first application of the simplified method in the overall performance calculation of the precooled engine reveals that the traditional low-dimensional model underestimates both the total pressure loss of the precooler and the fuel consumption for precooling, resulting in larger calculation deviations in the thrust and equivalence ratio, respectively. The values of thrust calculated with the high-dimensional virtual model show an average decrease of 2.01 % compared to those derived from the low-dimensional model. In addition, a higher Mach number results in lower effectiveness, higher air inlet temperature, and reduced resistance of the precooler to heat exchange imbalance caused by flow non-uniformity. These factors lead to an escalating relative deviation of the equivalence ratio between the two models, reaching 26.45 % at Mach 5.

Оптимизация гидрологических расчетов систем очистки поверхностного и дренажного стока воды

Objective: to develop a method for determining the optimal hydrological characteristics of systems for treating contaminated surface and drainage waters. Methods: the pollutant balance equation was applied. For comparison, the method of the Vodgeo Research Institute was used. The costs of treatment and environmental damage from pollution of watercourses were studied for various water levels of the year and the parameters of treatment facilities. The main parameters chosen are the types of pollutants (suspended substances and petroleum products) and the separation coefficient of the runoff in the separation chambers. Results: a method has been developed for optimization calculations of the hydrological characteristics of surface and drainage water treatment systems, taking into account the likelihood of runoff during high water and floods, the costs of construction and operation of treatment facilities and damage from pollution of watercourses. As an example, optimization calculations were performed for several options for treating melt, rain and drainage runoff. Practical importance: the method of optimization calculations of environmental protection will allow a more reasonable and accurate determination of the required degree of wastewater treatment, productivity and parameters of treatment facilities, and in some cases — to reduce the degree of pollution of watercourses.

Spectroscopy of N = 50 isotones with the valence-space density matrix renormalization group

The recently proposed combination of the valence-space in-medium similarity renormalization group (VS-IMSRG) with the density matrix renormalization group (DMRG) offers a scalable and flexible many-body approach for strongly correlated open-shell nuclei. We use the VS-DMRG to investigate the low-lying spectroscopy of N=50 isotones, which are characteristic for their transition between single-particle and collective excitations. We also study electromagnetic transitions and show the advantage of the VS-DMRG to capture the underlying physics more efficiently, with significantly improved convergence compared to state-of-the-art shell-model truncations. Combined with an analysis of quantum information measures, this further establishes the VS-DMRG as a valuable method for ab initio calculations of nuclei.

Neutron balance approach for inline critical rod position search calculation in Monte Carlo reactor analysis

The critical rod position search has been one of the issues in the Monte Carlo (MC) reactor analysis. This paper proposes a practical and simple approach for the critical rod position search based on the neutron balance equation and the monotonic relation between the control rod absorption rate and the total rod insertion length. The proposed method was implemented in an inline manner within the McCARD, the MC reactor design code, so that the critical rod position is calculated and updated for each fission source iteration. The numerical results in a typical fast reactor problem demonstrate the promising performance of the proposed method in the critical rod position search calculation. Furthermore, the cycle depletion calculation was performed to show the capability of the McCARD to simulate the rodded operation condition. By addressing the critical rod position search problem through the neutron balance approach, the applicability of the MC code in the advanced reactor design will be expanded.

Calculation of the minimum clinically important difference (MCID) using different methodologies: case study and practical guide

IntroductionEstablishing thresholds of change that are actually meaningful for the patient in an outcome measurement instrument is paramount. This concept is called the minimum clinically important difference (MCID). We summarize available MCID calculation methods relevant to spine surgery, and outline key considerations, followed by a step-by-step working example of how MCID can be calculated, using publicly available data, to enable the readers to follow the calculations themselves.MethodsThirteen MCID calculations methods were summarized, including anchor-based methods, distribution-based methods, Reliable Change Index, 30% Reduction from Baseline, Social Comparison Approach and the Delphi method. All methods, except the latter two, were used to calculate MCID for improvement of Zurich Claudication Questionnaire (ZCQ) Symptom Severity of patients with lumbar spinal stenosis. Numeric Rating Scale for Leg Pain and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire Walking Ability domain were used as anchors.ResultsThe MCID for improvement of ZCQ Symptom Severity ranged from 0.8 to 5.1. On average, distribution-based methods yielded lower MCID values, than anchor-based methods. The percentage of patients who achieved the calculated MCID threshold ranged from 9.5% to 61.9%.ConclusionsMCID calculations are encouraged in spinal research to evaluate treatment success. Anchor-based methods, relying on scales assessing patient preferences, continue to be the “gold-standard” with receiver operating characteristic curve approach being optimal. In their absence, the minimum detectable change approach is acceptable. The provided explanation and step-by-step example of MCID calculations with statistical code and publicly available data can act as guidance in planning future MCID calculation studies.

Theoretical Understanding of Electromigration-Related Surface Diffusion and Current-Induced Force in Ag-Pd Systems.

Electromigration, as a common reason for interconnect failure, is becoming increasingly important in the ongoing decrease in the integrated circuit manufacturing process. A study is being carried out utilizing the ab initio calculational method to gain a deeper understanding of electromigration, with a focus on the atom diffusion process in the Ag-Pd alloy system, a commonly used interconnect material. We begin by establishing that the primary mechanism of diffusion is step-edge diffusion on the (111) surface. Following this, we examine the current-induced force exerted on the migrating Ag atom. The Pd substitutional defect reveals an effect that increases the energy barrier of diffusion and decreases the current-induced force that powers the directional migration.

Static force from generalized Wilson loops on the lattice using the gradient flow

The static QCD force from the lattice can be used to extract ΛMS¯, which determines the running of the strong coupling. Usually, this is done with a numerical derivative of the static potential. However, this introduces additional systematic uncertainties; thus, we use another observable to measure the static force directly. This observable consists of a Wilson loop with a chromoelectric field insertion. We work in the pure SU(3) gauge theory. We use gradient flow to improve the signal-to-noise ratio and to address the field insertion. We extract ΛMS¯nf=0 from the data by exploring different methods to perform the zero-flow-time limit. We obtain the value 8t0ΛMS¯nf=0=0.629−26+22, where t0 is a flow-time reference scale. We also obtain precise determinations of several scales: r0/r1, 8t0/r0, 8t0/r1, and we compare these to the literature. The gradient flow appears to be a promising method for calculations of Wilson loops with chromoelectric and chromomagnetic insertions in quenched and unquenched configurations. Published by the American Physical Society 2024

Exploring the efficiency of a source-level model to predict hydrophone-based received noise levels of the St. Lawrence Estuary’s merchant fleet

The Enhancing Cetacean Habitat and Observation (ECHO) source-level model was statistically derived using nearly 10,000 vessel transits along Canada’s western coast. Before using this model in other areas, it is important to examine its efficiency in new environments and on other fleets. In this work, hydrophone-based acoustic recordings collected between August 3rd and September 16th of 2022 within the Saguenay-St. Lawrence Marine Park were used to investigate the applicability of the ECHO source-level model to Canada’s eastern fleet. Opportunistic transits of 71 merchant ships near (i.e., ≲3 km) the hydrophone were obtained. As an attempt to reduce computing times in the context of agent-based modeling, the reliability of the proposed analytic seabed critical angle (SCA) method for propagation losses calculations was examined and compared to robust, although time-consuming, numerical methods. Results generally show that the combination of the ECHO source-level model and our best estimates for propagation losses calculations does allow to reliably predict the acoustic footprint of the radiated noise levels by merchant ships in the acoustic module of the Marine Mammal and Maritime Traffic Simulator (3MTSim). However, computational gains could be marginal at best due to the analytic SCA method quickly becoming inconsistent with the numerical approach in range-dependent scenarios that often translate into long-range encounters.

Elastic Electron Scattering from Be, Mg, and Ca

We present a comprehensive set of theoretical results for differential, integrated, and momentum transfer cross sections for the elastic scattering of electrons by beryllium, magnesium, and calcium at energies below 1 keV. In addition, we provide Sherman function values for elastic electron scattering from calcium in the same energy range. This study extends the application of our method of calculations, already employed for barium and strontium, to all stable alkaline-earth-metal atoms. Our semi-empirical approach to treating target polarization has produced in our earlier work a satisfactory agreement with experimental values and precise theoretical results such as convergent close-coupling calculations for barium. The present data are expected to be of similar high accuracy, based on our previous success in similar calculations for barium and all inert gases.