Cascade Calculations Research Articles

Calculation of a square cascade using the bee colony algorithm

Calculation of a square cascade using the bee colony algorithm

Estimating Mild Cognitive Impairment and Mild Dementia due to Alzheimer’s disease in the United States

AbstractBackgroundIn the United States (US), early Alzheimer’s disease (AD) is underdiagnosed due to numerous factors such as inadequate lab testing, lack of symptom awareness, misdiagnosis, and social stigma. AD has a long prodromal stage, and the potential for early diagnosis is important to effectively use disease‐modifying drugs. Our research aims to estimate the prevalence of mild cognitive impairment (MCI) and mild dementia due to AD among individuals ≥60 years old in the US.MethodUsing currently available data from a comprehensive literature review in a population cascade calculation, this study estimates the diagnosed prevalence of early AD in the US. It also evaluates uncertainty associated with different estimates using all upper or all lower 95% confidence intervals reported in the literature and highlights data gaps for estimating the population living with MCI and mild dementia due to AD.ResultWe estimated that in 2022 approximately 666,646 individuals (0.87% of those aged 60 years and older) had MCI due to AD (range: 351,926 – 1,227,776) and approximately 620,850 individuals (0.81% of those aged 60 years and older) had mild dementia due to AD (range: 445,082 – 820,339). In a US population of 76 million aged 60 or older in 2022, the size of the population with MCI due to AD and mild dementia due to AD increased with age, from 103,947 individuals in people 60‐64 years of age to 264,915 in people ≥90 years of age.ConclusionCurrent data sources suggest that the range of prevalence of MCI due to AD or mild dementia due to AD in the US is wide, but estimates are similar to other studies in literature. Slight differences may reflect changes in diagnostic tools, alternative prevalence sources used in computation, and alternative (PET, CSF) cutoffs to determine amyloid positivity. As new amyloid‐targeting therapies become available, additional research to obtain accurate estimates on diagnosis and amyloid positivity in more real‐world populations are required to reduce uncertainty. Given challenges around diagnosis and access to technology and specialists, planning will be required to optimize the value of new treatment advances such as amyloid‐targeting therapies.

A heuristic technique for music recommendation using Haar cascade classifier through facial expressions

Human emotion assumes a fundamental part lately. Feeling depends on human sentiments which can be both communicated or not. Feelings communicate the human's singular way of behaving which can be in various structures. Extraction of the emotion states people individual condition of conduct. The goal of this task is to separate element from human face and identify feeling and to play music as indicated by the emotion identified. In this task, fostering a model to suggest dynamic music proposal framework in view of human feelings is our principal perspective. From the genuine face the emotion is recognized and when the mind-set is gotten from input picture, particular melodies for the state of mind would be played to hold the clients. In this methodology, the application gets associated with human sentiments accordingly giving an individualized touch to the clients. Our projected framework focuses on distinguishing the human face using Haar Cascade classifier. A few stages like face location utilizing webcam, facial feature extraction, look identification, with that interfacing with a music player will be followed. For exploratory outcomes, Haar cascade calculation and Computer vision along with CNN (Convolution Neural Network) for feeling discovery and music suggestion.

Atomic displacement damage energy model up to high recoil energy

Current analytical displacement damage models are derived for recoil energy below 24.9AZ4/3 keV. The present work studies the damage energy beyond this theoretical limit using SRIM Full Cascade (FC) and DART calculations. Notably, the three damage energies computed with different methods from the same SRIM simulation are not equal, whereas they are believed to be the same in principle. The method of directly subtracting the ionization energy from total recoil energy is recommended for both FC and Quick Calculation (QC) options. It is also observed that the damage energy seems to unphysically depend on the density of monatomic material in SRIM FC. While the classical analytical models imply the saturated damage energy for high recoil energy, this saturation is not observed in SRIM FC nor in the numerical solution of the Lindhard equation using reasonable electronic stopping powers.

Improved AVF-PLL-Based Position Estimation Scheme for SPMSM Sensorless Drives

The combination of a high-performance filter and phase-locked loop (PLL) has been presented as an effective alternative for the position estimation of a permanent magnet synchronous motor (PMSM) drive. However, the feedback delays existing in the practical implementation of the filter and PLL usually lead to position estimation deviation. To enhance the accuracy of position estimation, this paper proposes a sensorless control technology based on an improved adaptive vectorial filter (AVF) and PLL. First, the effect of feedback delay on the filtering performance of the AVF and the tracking performance of the PLL are analyzed. Then, corresponding delay compensation methods for the AVF and PLL are proposed. A compensation term based on the prediction of the filtered back electromotive force (EMF), which can repress the filtering performance degradation caused by feedback delays, is introduced and combined with the conventional AVF. As a result, the amplitude and phase shifts with the filtered back EMF can be effectively eliminated before applying it to the PLL. A differential calculation structure, which can ensure that the closed-loop transfer function of the equivalent ideal PLL is the same as the ideal PLL under the condition of feedback delay, is proposed to replace the cascade calculation structure of the conventional PLL. In addition, an open-loop deviation compensation method is integrated to eliminate the position estimation static deviation. The effectiveness of the proposed sensorless control technology is investigated by experimental tests.

Multiple photodetachment of oxygen anions via K -shell excitation and ionization: Direct double-detachment processes and subsequent deexcitation cascades

Experimental cross sections for m-fold photodetachment (m=2-5) of oxygen anions via K-shell excitation and ionization were measured in the photon-energy range of 525-1500 eV using the photon-ion merged-beams technique at a synchrotron light source. The measured cross sections exhibit clear signatures of direct double detachment, including double K-hole creation. The shapes of the double-detachment cross sections as a function of photon energy are in accord with Pattard's [J. Phys. B 35, L207 (2002)] empirical scaling law. We have also followed the complex deexcitation cascades that evolve subsequently to the initial double-detachment events by systematic large-scale cascade calculations. The resulting theoretical product charge-state distributions are in good agreement with the experimental findings.

Collision-induced radiative quenching and other disintegration modes of the 2s state of muonic hydrogen and deuterium atoms

The formation and various disintegration modes of $2s$ states for muonic hydrogen and deuterium atoms at kinetic energies both above and below the $2s-2p$ threshold are studied. The cross sections of the collision-induced radiative quenching, elastic scattering, and Coulomb deexcitation of $(\mu^- p)_{2s}$ and $(\mu^- d)_{2s}$ atoms in collisions with ordinary hydrogen and deuterium atoms at collision energies below the $2s-2p$ threshold are calculated in the framework of the close-coupling approach. The basis set includes all open and closed channels corresponding to exotic-atom states with principal quantum number $n$ from 1 up to 30. Results of these numerical quantum-mechanical calculations of cross sections are used as input data for detailed cascade calculations. The kinetics of atomic cascade for $\mu^- p$ and $\mu^-d$ atoms is studied in the wide range of the relative target densities, $\varphi = 10^{-8} -1$ applying the improved version of the cascade model. It is shown that the collision-induced radiative quenching gives a significant contribution to the total disintegration of the $2s$ state of muonic atoms at energies below the $2s-2p$ threshold. The initial population of the $2s$ state for both muonic hydrogen and deuterium atoms, absolute intensities and probabilities of the different disintegration modes as well as their lifetimes are calculated for the fractions with kinetic energies above and below the $2s-2p$ threshold. The obtained results are compared with the known experimental data.

On the use of SRIM for calculating vacancy production: Quick calculation and full-cascade options

The vacancy production behavior for a broad range of incident ion-target combinations were examined by using both the full cascade (F-C) and quick calculation of damage (Q-C) options of Stopping and Range of Ions in Matter (SRIM-2013) code. Vacancy production for each option was evaluated using both the convenient vacancy text file in SRIM, and by manual manipulation of the energy transfer, ionization, and phonon text file data to calculate the depth-dependent damage energy for the Norgett-Robinson-Torrens (NRT) defect production model. The F-C vacancy text file method was observed to overpredict vacancy production by a factor of ~1.1 to 4 times when compared to values calculated using the F-C damage energy method or either of the SRIM Q-C methods. Based on our extensive data set obtained for 142 unique bombarding ion-target combinations, we show that the SRIM F-C vacancy text file method should not be used for vacancy production calculations. This error appears to be due to mischaracterization within the SRIM F-C option of some near-threshold replacement events as vacancies instead of replacements. Use of the latest SRIM stopping powers in the SRIM F-C approach provides a better calculation of electronic and nuclear stopping compared to the Lindhard stopping power analytical approximation used to calculate the damage energy of recoil atoms in the SRIM Q-C option, and therefore SRIM F-C approach is deemed to provide the best accuracy for vacancy production (within the binary collision approximation) as long as the damage energy method is used. Alternately, the SRIM Q-C option using either the vacancy.txt or damage energy method provides relatively fast calculation speeds with moderate quantitative differences from the F-C damage energy results (~0 to ~ 30% for the investigated ion-target cases).

Ultrafast x-ray pump x-ray probe transient absorption spectroscopy: A computational study and proposed experiment probing core-valence electronic correlations in solvated complexes.

Femtosecond x-ray pump-x-ray probe experiments are currently possible at free electron lasers such as the linac coherent light source, which opens new opportunities for studying solvated transition metal complexes. In order to make the most effective use of these kinds of experiments, it is necessary to determine which chemical properties an x-ray probe pulse will measure. We have combined electron cascade calculations and excited-state time-dependent density functional theory calculations to predict the initial state prepared by an x-ray pump and the subsequent x-ray probe spectra at the Fe K-edge in the solvated model transition metal complex, K4FeII(CN)6. We find several key spectral features that report on the ligand-field splitting and the 3p and 3d electron interactions. We then show how these features could be measured in an experiment.

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Abstract Using the photon–ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe2+ ions in the energy range of 690–920 eV. This range contains thresholds and resonances associated with ionization and excitation of 2p and 2s electrons. Calculations were performed to simulate the total absorption spectra. The theoretical results show very good agreement with the experimental data, if overall energy shifts of up to 2.5 eV are applied to the calculated resonance positions and assumptions are made about the initial experimental population of the various levels of the Fe2+([Ar]3d 6) ground configuration. Furthermore, we performed extensive calculations of the Auger cascades that result when an electron is removed from the 2p subshell of Fe2+. These computations lead to a better agreement with the measured product-charge-state distributions as compared to earlier work. We conclude that the L-shell absorption features of low-charged iron ions are useful for identifying gas-phase iron in the interstellar medium and for discriminating against the various forms of condensed-phase iron bound to composite interstellar dust grains.

Centrifugal Separation of Carbon Isotopes Using Carbon Tetrafluoride as Processing Gas

At present, the application of carbon isotope is becoming more and more extensive, especially in the field of medical testing, and the demand for 13C in high abundance is fast increasing. Using carbon tetrafluoride (CF4) as separation medium, study on centrifugal separation of carbon isotopes was carried out. Single-centrifuge experiments were done based on modified domestic gas centrifuges. As a result, the separation factor and single-centrifuge separative power under different working conditions were obtained. Based on the results of single-centrifuge separation experiments, cascade calculation of the enrichment of 13C isotope was conducted by ideal cascade. According to calculation results, through two cascade separations, 13C isotope could be enriched from 30% to above 99% in abundance. The study laid a good basement for production of 13C isotope in high abundance.

Separation of boron isotopes in optimal cascade of uniflow gas centrifuges

Was considered a problem of an optimization of concurrent gas centrifuges for separation of Boron isotopes in form of trifluoride BF3. As the criteria was used a minimum of total number of gas centrifuges upon the given external parameters of the cascades’ scheme. The method is based on the analytical relationships for the flows of stages, received under approximating minimization of the total feed flow. Conducted cascade calculations showed that it is possible to obtain BF3 with enrichment up to 99.9 % of 10B in the selection and up to 0.1 % in the waste, which is equivalent to 99.9 % of 11B.

Radiative Cascade Repopulation of 1s2s2p 4P States Formed by Single Electron Capture in 2–18 MeV Collisions of C4+ (1s2s 3S) with He

This study focuses on the details of cascade repopulation of doubly excited triply open-shell C3+(1s2s2p)4P and 2P± states produced in 2–18 MeV collisions of C4+(1s2s3S) with He. Such cascade calculations are necessary for the correct determination of the ratio R of their cross sections, used as a measure of spin statistics [Madesis et al. PRL 124 (2020) 113401]. Here, we present the details of our cascade calculations within a new matrix formulation based on the well-known diagrammatic cascade approach [Curtis, Am. J. Phys. 36 (1968) 1123], extended to also include Auger depopulation. The initial populations of the 1s2snℓ4L and 1s2snℓ2L levels included in our analysis are obtained from the direct nℓ single electron capture (SEC) cross sections, calculated using the novel three-electron close-coupling (3eAOCC) approach. All relevant radiative branching ratios (RBR) for n≤4 were computed using the COWAN code. While doublet RBRs are found to be very small, quartet RBRs are found to be large, indicating cascade feeding to be important only for quartets, consistent with previous findings. Calculations including up to third order cascades, extended to n→∞ using an n−3 SEC model, showed a ∼60% increase of the 1s2s2p4P populations due to cascades, resulting, for the first time, in R values in good overall agreement with experiment.

The Optimization of Natural Gas Utilization Network in Single Region Using Pinch Analysis Method

Natural gas is one of the cleanest energy resources and may have potency to replace crude oil as main energy resource in several decades. There are some aspects which must be concern in the development of the natural gas industry including processing, storing, distributing and utilizing of the natural gas. The network of natural gas supply also should be generated to obtain the maximum natural gas recovery. However, it is difficult to determine the most suitable network system to connect the supply and demand of natural gas due to their different time scale, flowrate and capacity. There are some studies which investigating the network system to connect the supply and demand of natural gas but there are no systematical method in determination of the optimum natural gas network in single region supply-chain using pinch analysis. Therefore, in this study, a systematical method was developed to design natural gas network system in single region (East Java) using pinch analysis. The concept of natural gas cascade calculation was introduced. The heuristics of natural gas pairing between source and sink streams in grid diagram analysis was developed. Using 0-year time minimum difference give the amount of unutilized supply with value of 258.4 billion standard cubic feet (BCF) while 3-year time minimum difference give the amount of alternative and unutilized supply with value of 639.3 BCF and 897.7 BCF, respectively. The grid diagram heuristics developed in this study gives same results with the cascade calculation result.

Near L-edge Single and Multiple Photoionization of Triply Charged Iron Ions

Abstract Relative cross sections for m-fold photoionization (m = 1,…, 5) of Fe3+ by single-photon absorption were measured employing the photon-ion merged-beams setup PIPE at the PETRA III synchrotron light source operated at DESY in Hamburg, Germany. The photon energies used spanned the range of 680–950 eV, covering both the photoexcitation resonances from the 2p and 2s shells, as well as the direct ionization from both shells. Multiconfiguration Dirac–Hartree–Fock (MCDHF) calculations were performed to simulate the total photoexcitation spectra. Good agreement was found with the experimental results. These computations helped to assign several strong resonance features to specific transitions. We also carried out Hartree–Fock calculations with relativistic extensions taking into account both photoexcitation and photoionization. Furthermore, we performed extensive MCDHF calculations of the Auger cascades that result when an electron is removed from the 2p and 2s shells of Fe3+. Our theoretically predicted charge-state fractions are in good agreement with the experimental results, representing a substantial improvement over previous theoretical calculations. The main reason for the disagreement with the previous calculations is their lack of inclusion of slow Auger decays of several configurations that can only proceed when accompanied by de-excitation of two electrons. In such cases, this additional shake-down transition of a (sub)valence electron is required to gain the necessary energy for the release of the Auger electron.

Cascade calculation with schematic interactions

In previous works we considered schematic Hamiltonians represented by simplified matrices. We defined two transition operators and calculated transition strengths from the ground state to all excited states. In many cases the strengths decreased nearly exponentially with the excitation energy. Now we do the reverse. We start with the highest energy state and calculate the cascade of transitions until the ground state is reached. On a log plot we show the average transition strength as a function of the number of energy intervals that were crossed. We give an analytic proof of exponential behavior for transition strength in the weak coupling limit for the [Formula: see text] transition operator.

Исследование способов испытания лопаточных диффузоров центробежных компрессорных ступеней в виртуальной аэродинамической трубе

A mathematical model of a vaned diffuser of a centrifugal compressor stage can be constructed based on the results of mass CFD-calculations, similar to that of vaneless diffusors. The methods for calculating the annular cascade and the straight cascade differ due to the existence of vaneless diffusor sections in front of the cascade and behind it. The rational dimensions of these sections are determined. The calculations of two-dimensional cascades without restricting walls appear to be irrational. The calculation is effective for a sector with one vane channel, a moderate number of cells, and the turbulence model k–ε. Averaging the flow parameters at the blade cascade exit leads to ambiguous results. To calculate the characteristics of the blade cascade, the parameters in a section with a diameter equal to 1.85 of the diameter of the blade cascade exit should be used. In domestic and foreign literature, it is customary to emphasize the effectiveness of the CFD methods that replace physical experiments. Calculations of the compressor stages are called virtual rig testing, while those of the blade cascade are known as virtual wind tunnel testing. To study stationary flow, as a virtual wind tunnel, it suffices to consider the blade cascade itself, the preceding and the subsequent vaneless spaces.

Nano-patterning of cuprate superconductors by masked He+ ion irradiation: 3-dimensional profiles of the local critical temperature

Irradiation of cuprate high-Tc superconductors with light ions of moderate energy creates point defects that lead to a reduction or full suppression of the critical temperature. By shaping the ion flux with a stencil mask, nanostructures for emerging superconducting electronics can be fabricated. The 3-dimensional shape of such defect landscapes is examined, based on calculations of full collision cascades and atom displacements. A relation between the calculated defect density and experimental values of the critical temperature in thin YBa2Cu3O7−δ films is etablished that allows to determine the distribution of local Tc’s and its 3-dimensional visualization. The results confirm that, using 75 keV He+ ion irradiation and a stencil mask, well-defined patterns of non-superconducting material in the superconducting matrix can be produced with low blurring.

Initial quantum levels of captured muons in CO, CO2, and COS

The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets of CO, CO2, and COS below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.

Quick calculation of damage for ion irradiation: implementation in Iradina and comparisons to SRIM

Binary collision approximation (BCA) calculation allows for two types of damage calculation: full cascade and quick calculations. Full cascade mode describes fully the cascades while in quick calculations, only the trajectory of the ion is followed and effective formulas give an estimation of the damage resulting from each collision of the ion. We implement quick calculation of damage in the Iradina code both for elemental and multi-component solids. Good agreement is obtained with SRIM. We show that quick calculations are unphysical in multi-component systems. The choice between full cascade and quick calculations is discussed. We advise to favour full cascade over quick calculation because it is more grounded physically and applicable to all materials. Quick calculations remain a good option for pure solids in the case of actual quantitative comparisons with neutron irradiations simulations in which damage levels are estimated with the NRT (Norgett-Robinson and Torrens) formulas.