Elementary Model Research Articles

Research on motion target detection based on infrared biomimetic compound eye camera.

The cooled mid-wave infrared biomimetic compound eye camera has wide range of applications, such as industrial inspection, military project, and security. Due to the low resolution of individual eyes and the large field view of the imaging system, existing motion target enhancement and detection algorithms cannot effectively detect all potential targets. To address this issue, we propose an improved elementary motion detector model that combines a double-layer ON_OFF channel and a cross-type computational architecture, which is able to suppress a stationary background and enhance moving targets. In order to further reduce the missed detection, we designed the spatial and temporal consistency detection methods of the compound eye structure, which further improved the accuracy and stability of the detection results. The experimental results show that our method can fully utilize the features of the image and can be applied to the enhancement and detection of moving objects in complex scenes, and the detection efficiency is significantly improved.

A mathematical model for wind-generated particle–fluid flow fields with an application to the helicopter cloud problem

We develop a model for the interaction of a fluid flowing above an otherwise static particle bed, with generally the particles being entrained or detrained into the fluid from the upper surface of the particle bed, and thereby forming a fully two phase fluidized cloud above the particle bed. The flow in this large-scale fluidized region is treated as a two-phase flow, whilst the key processes of entrainment and detrainment from the particle bed are treated by examining the local dynamical force balances on the particles in a thin transition layer at the interface between the fully fluidized region and the static particle bed. This detailed consideration leads to the formation of an additional macroscopic boundary condition at this interface, which closes the two-phase flow problem in the bulk fluidized region above. We then introduce an elementary model of the well-known helicopter brownout problem, and use the theory developed in the first part of the paper to fully analyse this model, both analytically and numerically.

Maximum dust-to-gas mass flux ratio in spherically expanding dusty-gas flow

In this paper, we consider the motion of a solid spherical particle in a spherically expanding gas flow as an elementary model of the gas-dust atmosphere of a comet. Based on the results of numerical simulations we propose an approximation for the terminal dust velocity and an estimate of the maximum dust-to-gas mass flux ratio (in a dusty-gas flow with the dust size distribution given by a power law) which is consistent with assumption of negligible impact of dust on the gas flow (frequently used in simulations of dusty gas flows).

Comprehensive Insight into Regular Damped Oscillatory Structures from Effective Electromagnetic Form Factor Data of Some Mesons and Nucleons

Regular damped oscillatory structures from the “effective” electromagnetic form factors of the hadrons h=π±,K±,K0,p,n were investigated. The “effective” electromagnetic form factor behaviors were calculated from the experimental data on the total cross-sections σtot(e+e−→hh¯) with errors. The apparent oscillations were observed for the first time for the proton, and we show, also taking other hadrons into consideration, that they are an arbitrary artifact resulting from a very simplistic theoretical description based on an elementary three-parameter model. If the data are described by a more appropriate and physically well-founded Unitary and Analytic model, then the oscillations disappear. In spite of this, if the three-parameter model is used to describe the “effective” electromagnetic form factor data, an interesting phenomenon is observed. The oscillations are opposite for particles which form an isospin doublet. By using the physically well-founded Unitary and Analytic model, it is demonstrated that this feature originates from the special transformation properties of the electromagnetic current of the corresponding particles in the isotopic space.

Simulation of Total Harmonic Distortion of Solid Oxide Fuel Cells for Carbon Deposition Detection

Abstract Identifying the degradation mechanisms at the early stage of operation is important for the long-term operation of solid oxide fuel cells (SOFCs). Compared to conventional methods, total harmonic distortion analysis (THDA) can significantly reduce the test time for identifying performance degradation during SOFC operation. In this study, a one-dimensional transient elementary reaction kinetic model of an SOFC fueled with syngas is developed. The model incorporates the coupling effect of elementary chemical and electrochemical reactions, the electrode microstructure, the charge and mass transport processes, and the detailed evolution reaction of surface adsorbed carbon. A THDA simulation calculation method was developed and applied to determine the failure mode of anode carbon deposition. The amplitude, duration, and harmonic number of the perturbation signal are determined to improve fault detection for THDs. The results show that the use of THD can not only detect carbon accumulation behavior at the early stage of SOFC operation but also distinguish the specific degradation mechanism caused by carbon deposition: the hindered SOFC charge transfer reaction can be detected in the frequency range of 100-4000 Hz, and the hindered gas diffusion process inside the anode can be detected in the frequency range of 0.01-10 Hz.

Framework for a Research-Based and Interdisciplinary Use of Sensors in Elementary Teacher Education.

Sensors should be integrated into teacher education, as they are essential tools in the digital practices needed for full participation in society. Electronic sensors can be used as laboratory/scientific tools, as everyday mobile learning tools, and as epistemic mediators in several scientific fields, as well as in interdisciplinary approaches. In this way, electronic sensors can play multiple roles in the main dimensions of teacher education. The aim of the research presented in this paper was to create a framework for the research-based and interdisciplinary use of sensors in elementary teacher education, based on the thematic analysis of seven case studies implemented in Portugal. The thematic categories used in the cross-case analysis were fundamental in revealing the different roles played by sensors in the different phases of the didactic sequences of the cases. Subsequently, the thematic analysis made it possible to identify patterns of affordances of sensors and to relate the multiple roles of electronic sensors to different areas of the Portuguese elementary teacher education model. The research synthesis made it possible to outline the framework perspectives. The resulting framework systematized and highlighted the affordances of sensors in pre-service and in-service elementary teacher education as scientific, epistemic, interdisciplinary, and didactic mediators. These affordances were revealed to be particularly important in data-driven inquiry problem-solving, pedagogical content knowledge, and professional knowledge development. The framework created can be expanded in future related research.

Theoretical study on gas‐phase reactions during chemical vapor deposition of TixAl1–xN from TiCl4, AlCl3, and NH3

AbstractFcc‐TixAl1–xN (TiAlN) coatings synthesized via chemical vapor deposition (CVD) reduce cutting tool wear. Although CVD conditions reportedly influence coating quality, no quantitative guidelines are yet available. To quantitatively study the film‐forming mechanism of TiAlN CVD, the gas composition over the surface must be known. Therefore, we developed a gas‐phase elementary reaction model for TiAlN CVD derived from TiCl4/AlCl3/NH3. First, we constructed a novel thermodynamic dataset including molecules that contained both Ti and Al, and calculated the equilibrium composition. Thermal equilibrium calculations in the gas phase showed that the most stable species were AlCl3 and TiCl3 rather than TiCl4. An elementary reaction model was constructed based on the kinetics of the gas‐phase species that were generated. Kinetic analysis revealed that gas‐phase reactions were largely absent under our reactor conditions. The thermal equilibrium calculations indicated that TiCl4 may have given rise to TiCl3. Thus, other reaction pathways of TiCl4 to TiCl3 were explored. We calculated the reaction rate constants of 12 reactions of Ti species and added them to the model, which revealed that TiCl4 decomposed to TiCl3 via TiCl3NH2. Under our conditions, TiCl4 and TiCl3NH2 are the major Ti species and AlCl3 and AlCl2NH2 are the major Al species, which suggests that some of these species may form films. Unlike in the earlier reaction model, NH2 and H radicals were produced, which may have contributed to the surface reactions. For reactors with large Surface/Volume ratio of reactor, the effects of gas‐phase reactions should be considered. Our reaction model enables estimation of the partial pressures of reactor gas species and will therefore aid study of the TiAlN deposition mechanism.

Kinetics and mechanisms of non-radically and radically induced degradation of bisphenol A in a peroxymonosulfate-chloride system

Bisphenol A, a hazardous endocrine disruptor, poses significant environmental and human health threats, demanding efficient removal approaches. Traditional biological methods struggle to treat BPA wastewater with high chloride (Cl−) levels due to the toxicity of high Cl− to microorganisms. While persulfate-based advanced oxidation processes (PS-AOPs) have shown promise in removing BPA from high Cl− wastewater, their widespread application is always limited by the high energy and chemical usage costs. Here we show that peroxymonosulfate (PMS) degrades BPA in situ under high Cl− concentrations. BPA was completely removed in 30 min with 0.3 mM PMS and 60 mM Cl−. Non-radical reactive species, notably free chlorine species, including dissolved Cl2(l), HClO, and ClO− dominate the removal of BPA at temperatures ranging from 15 to 60 °C. Besides, free radicals, including •OH and Cl2•−, contribute minimally to BPA removal at 60 °C. Based on the elementary kinetic models, the production rate constant of Cl2(l) (32.5 M−1 s−1) is much higher than HClO (6.5 × 10−4 M−1 s−1), and its degradation rate with BPA (2 × 107 M−1 s−1) is also much faster than HClO (18 M−1 s−1). Furthermore, the degradation of BPA by Cl2(l) and HClO were enlarged by 10- and 18-fold at 60 °C compared to room temperature, suggesting waste heat utilization can enhance treatment performance. Overall, this research provides valuable insights into the effectiveness of direct PMS introduction for removing organic micropollutants from high Cl− wastewater. It further underscores the critical kinetics and mechanisms within the PMS/Cl⁻ system, presenting a cost-effective and environmentally sustainable alternative for wastewater treatment.

Unconventional edge states in a two-leg ladder

Some popular mechanisms for restricting the diffusion of waves include introducing disorder (to provoke Anderson localization) and engineering topologically non-trivial phases (to allow for topological edge states to form). However, other methods for inducing somewhat localized states in elementary lattice models have been historically much less studied. Here we show how edge states can emerge within a simple two-leg ladder of coupled harmonic oscillators, where it is important to include interactions beyond those at the nearest neighbor range. Remarkably, depending upon the interplay between the coupling strength along the rungs of the ladder and the next-nearest neighbor coupling strength along one side of the ladder, edge states can indeed appear at particular energies. In a wonderful manifestation of a type of bulk-edge correspondence, these edge state energies correspond to the quantum number for which additional stationary points appear in the continuum bandstructure of the equivalent problem studied with periodic boundary conditions. Our theoretical results are relevant to a swathe of classical or quantum lattice model simulators, such that the proposed edge states may be useful for applications including waveguiding in metamaterials and quantum transport.

Implementation of the Elementary School Administration Model in Increasing the Effectiveness of Learning Management

This research aims to investigate the implementation of the elementary school administration model in increasing the effectiveness of learning management in the school environment. The administrative model implemented combines various strategies and approaches that focus on optimizing management, improving the quality of teaching, and strengthening relationships between all relevant stakeholders. The research method used is a qualitative approach with data collection techniques through in-depth interviews, observation and document analysis. Research respondents included principals, teachers, administrative staff, and students from several elementary schools that participated in the implementation of the administrative model. The research results show that the implementation of the elementary school administration model has contributed significantly to increasing the effectiveness of learning management. This model helps in increasing administrative efficiency, optimal use of resources, and more targeted learning planning. In addition, this administrative model encourages better collaboration between school stakeholders, including collaboration between school principals, teachers, administrative staff, and parents. This research concludes that the implementation of a holistic and collaboration-based elementary school administration model can provide great benefits in increasing the effectiveness of learning management. This model can be a reference for elementary schools in improving the quality and achievement of education and creating a more effective and competitive learning environment.

Present Status of Spectroscopy of the Hyperfine Structure and Repolarization of Muonic Helium Atoms at J-PARC

The mass mμ− of the negative muon is one of the parameters of the elementary particle Standard Model and it allows us to verify the CPT (charge–parity–time) symmetry theorem by comparing mμ− value with the mass mμ+ of the positive muon. However, the experimental determination precision of mμ− is 3.1ppm, which is an order of magnitude lower than the determination precision of mμ+ at 120ppb. The authors aim to determine mμ− and the magnetic moment μμ− with a precision of O(10ppb) through spectroscopy of the hyperfine structure (HFS) of muonic helium-4 atom (4Heμ−e−) under high magnetic fields. He4μ−e− is an exotic atom where one of the two electrons of the He4 atom is replaced by a negative muon. To achieve the goal, it is necessary to determine the HFS of He4μ−e− with a precision of O(1ppb). This paper describes the determination procedure of the HFS of He4μ−e− in weak magnetic fields reported recently, and the work towards achieving the goal of higher precision measurement.

Insight into the complex ammonia decomposition/oxidation kinetics in ammonia protonic ceramic fuel cells via elementary modeling

AbstractThe protonic ceramic fuel cells (PCFCs) can convert the chemical energy of fuel directly into electric power, with the advantages of high efficiency and alternative fuel range at intermediate temperatures. Ammonia has been regarded as a promising fuel for PCFCs due to its carbon‐free and hydrogen‐rich properties, high volumetric energy density and easy storage/transportation. However, the performance of ammonia PCFCs (NH3‐PCFCs) is far inferior to the hydrogen PCFCs (H2‐PCFCs) because of the sluggish and complex kinetics at anodes. In this study, we established an elementary reaction kinetic model for NH3‐PCFCs, investigated the effect of reaction parameters, anode components and reaction partition, and explored the coupling mechanism between the ammonia decomposition and electrochemical reaction. Importantly, the ammonia decomposition and electrochemical reaction can be flexibly regulated by adjusting anode parameters, then affecting the performance ratio of NH3‐PCFCs and H2‐PCFCs. The detailed rate‐determining steps were further identified by experimental and model analysis. Thus, the ammonia/hydrogen performance ratio of the cell can exceed 95% at 550°C after accelerating the ammonia decomposition reaction. Our work provides insights into the kinetics in NH3‐PCFCs for improving their performance with optimization.

Application of elementary probability models for text homogeneity and segmentation: A case study of Bible

Application of elementary probability models for text homogeneity and segmentation: A case study of Bible

Development of an Elementary Reaction-Based Kinetic Model to Predict the Aqueous-Phase Fate of Organic Compounds Induced by Reactive Free Radicals.

ConspectusAqueous-phase free radicals such as reactive oxygen, halogen, and nitrogen species play important roles in the fate of organic compounds in the aqueous-phase advanced water treatment processes and natural aquatic environments under sunlight irradiation. Predicting the fate of organic compounds in aqueous-phase advanced water treatment processes and natural aquatic environments necessitates understanding the kinetics and reaction mechanisms of initial reactions of free radicals with structurally diverse organic compounds and other reactions. Researchers developed conventional predictive models based on experimentally measured transformation products and determined reaction rate constants by fitting with the time-dependent concentration profiles of species due to difficulties in their measurements of unstable intermediates. However, the empirical treatment of lumped reaction mechanisms had a model prediction limitation with respect to the specific parent compound's fate. We use ab initio and density functional theory quantum chemical computations, numerical solutions of ordinary differential equations, and validation of the outcomes of the model with experiments. Sensitivity analysis of reaction rate constants and concentration profiles enables us to identify an important elementary reaction in formating the transformation product. Such predictive elementary reaction-based kinetics models can be used to screen organic compounds in water and predict their potentially toxic transformation products for a specific experimental investigation.Over the past decade, we determined linear free energy relationships (LFERs) that bridge the kinetic and thermochemical properties of reactive oxygen species such as hydroxyl radicals (HO•), peroxyl radicals (ROO•), and singlet oxygen (1O2); reactive halogen species such as chlorine radicals (Cl•) and bromine radicals (Br•); reactive nitrogen species (NO2•); and carbonate radicals (CO3•-). We used literature-reported experimental rate constants as kinetic information. We considered the theoretically calculated aqueous-phase free energy of activation or reaction to be a kinetic or a thermochemical property, and obtained via validated ab initio or density functional theory-based quantum chemical computations using explicit and implicit solvation models. We determined rate-determining reaction mechanisms involved in reactions by observing robust LFERs. The general accuracy of LFERs to predict aqueous-phase rate constants was within a difference of a factor of 2-5 from experimental values.We developed elementary reaction-based kinetic models and predicted the fate of acetone induced by HO• in an advanced water treatment process and methionine by photochemically produced reactive intermediates in sunlit fresh waters. We provided mechanistic insight into peroxyl radical reaction mechanisms and critical roles in the degradation of acetone and the formation of transformation products. We highlighted different roles of triplet excited states of two surrogate CDOMs, 1O2, and HO•, in methionine degradation. Predicted transformation products were compared to those obtained via benchtop experiments to validate our elementary reaction-based kinetic models. Predicting the reactivities of reactive halogen and nitrogen species implicates our understanding of the formation of potentially toxic halogen- and nitrogen-containing transformation products during water treatment processes and in natural aquatic environments.

Feynman checkers: External electromagnetic field and asymptotic properties

In this paper, we study Feynman checkers, one of the most elementary models of electron motion. It is also known as a one-dimensional quantum walk or an Ising model at an imaginary temperature. We add the simplest non-trivial electromagnetic field and find the limits of the resulting model for small lattice step and large time, analogous to the results by Narlikar from 1972 and Grimmet–Jason–Scudo from the 2000s. It turns out that the limits in the model with the added field are obtained from the ones without field by mass renormalization. Also, we find an exact solution of the resulting model.

Optimal fissile distribution in multiplying systems: Illustrative examples with Monte Carlo simulation and Pontryagin’s maximum principle

In multiplying systems, such as nuclear reactors and criticality experiments, it is desirable to place the fissile material in the optimal or ‘best’ way to reduce the critical mass of the system as well as to achieve uniform fuel burnup. This paper considers two methods, namely Pontryagin’s maximum principle (PMP) and Monte Carlo (MC) perturbation for estimating a minimum critical mass configuration. These methods are applied to an elementary multizone model of a pressurized water reactor (PWR) and a criticality experiment to estimate the minimum critical mass. It is found that while two-group diffusion theory with PMP predicts a minimum critical mass, more detailed MC simulations with MCNP5 show a consistent reduction in critical mass when fissile fuel is placed in inner zones. Such a distribution reduces the fissile material requirement but is undesirable due to the higher power peaking. MC simulations show that for a three-zone model of the KORI 1 PWR, a uniform fissile distribution gives criticality for 1.09 atomic percent (at.%) enrichment, whereas non-uniform fissile distribution (0.6, 1.6, 0.6 at.%) reduces the critical mass by 14%. The changes found from MC simulations were subsequently predicted from first- and second-order derivative sampling. It was found that substantial computational savings can be achieved for large-scale optimization problems. In the case of a criticality experiment, MC derivative sampling was also used to estimate optimal fissile distribution for minimizing the critical mass.

Local thermal non-equilibrium effects on phase transition of fiber reinforced thermoplastic composites with temperature-dependent heat generation

Under the excitation of external fields, fiber reinforced thermoplastic (FRTP) composites can be thermally processed due to the internal heat generation, in which the local thermal non-equilibrium (LTNE) can be significant during the phase transition. In this study, a representative elementary volume scale Lattice Boltzmann model was developed to simulate the phase transition process of FRTP composites with the temperature-dependent internal heat source. The results from LTNE model and local thermal equilibrium (LTE) model were compared in terms of the phase interface evolution and the local temperature difference between fibers and matrix, so that the LTNE effects on phase transition behaviors were examined with different material properties and internal heat sources. It is found that the LTNE effects cannot be ignored in FRTP composites, and the main mechanisms include the dynamic local heat generation, endothermic phase transition of matrix, and relatively high thermal conductivity of fiber. A small heat exchange between the fibers and matrix results in a large local temperature difference and a slow phase transition. A high internal heat generation enhances the phase transition and LTNE effects, but an increase in the temperature range for heat generation leads to a slow phase transition with slight change in LTNE effects. With the increase of matrix fraction, LTNE effects first increase and then decrease due to the combined results of the more internal heat generation and the increase of endothermic mass of matrix and the less heat loss through fibers. This study is significant for guiding the reliable thermal processing of FRTP composites in emerging industrial applications.

Моделювання акустичного поля на основі дисперсії звуку при відбитті трасуючих хвиль на відкритих майданчиках

A method of numerical modeling of acoustic fields in open areas with the possibility of parallelization of calculations is proposed. This method is part of a developed software solution that allows you to perform physical field modeling in various subject areas, being scalable in the sense of using an arbitrary set of parallel calculators. The use of existing modeling systems is associated with great difficulties in solving complex problems with a high degree of detail of the simulated object. Greater accuracy implies a high degree of discretization, a greater number of elementary model calculations performed. Parallel and distributed computing systems have a much better ratio of accuracy-approximation and time and cost costs compared to single-processor systems. Modern general purpose modeling systems use a simplified ray model of sound propagation, which neglects diffractional and interference effects, which are often critical in industrial acoustics. The article proposed a method based on the approximation of the principle of superposition of sound fields. It is accurate, while the linearity of the equations of acoustics is relevant. The basis is the Rayleigh integral and the approximation of reflective surfaces by flat point radiators. A parallel form of such a method is presented, as well as an analysis of its properties, both in sequential and parallel forms.

An elementary model for an advancing autoignition front in laminar reactive co-flow jets injected into supercritical water

In this paper we formulate and analyze an elementary model for the propagation of advancing autoignition fronts in reactive co-flow fuel/oxidizer jets injected into an aqueous environment at pressures exceeding the critical point of water. This work is motivated by the experimental studies of autoignition of hydrothermal flames performed at the high pressure laboratory of the NASA Glenn Research Center. Guided by experimental observations, we use several simplifying assumptions that allow the derivation of a simple, still experimentally feasible, mathematical model for the propagation of advancing ignition fronts. We analyze the model by means of asymptotic and numerical techniques and discuss feasible regimes of propagation of advancing ignition fronts. We hope that the present study will be helpful for the interpretation of existing experimental data and guiding of future experiments.

Ab Initio and Kinetic Modeling of β-d-Xylopyranose under Fast Pyrolysis Conditions.

Lignocellulosic biomass is an abundant renewable resource that can be upgraded to chemical and fuel products through a range of thermal conversion processes. Fast pyrolysis is a promising technology that uses high temperatures and fast heating rates to convert lignocellulose into bio-oils in high yields in the absence of oxygen. Hemicellulose is one of the three major components of lignocellulosic biomass and is a highly branched heteropolymer structure made of pentose, hexose sugars, and sugar acids. In this study, β-d-xylopyranose is proposed as a model structural motif for the essential chemical structure of hemicellulose. The gas-phase pyrolytic reactivity of β-d-xylopyranose is thoroughly investigated using computational strategies rooted in quantum chemistry. In particular, its thermal degradation potential energy surfaces are computed employing Minnesota global hybrid functional M06-2X in conjunction with the 6-311++G(d,p) Pople basis set. Electronic energies are further refined by performing DLPNO-CCSD(T)-F12 single-point calculations on top of M06-2X geometries using the cc-pVTZ-F12 basis set. Conformational analysis for minima and transition states is performed with state-of-the-art semiempirical quantum chemical methods coupled with metadynamics simulations. Key thermodynamic quantities (free energies, barrier heights, enthalpies of formation, and heat capacities) are computed. Rate coefficients for the initial steps of thermal decomposition are computed by means of reaction rate theory. For the first time, a detailed elementary reaction kinetic model for β-d-xylopyranose is developed by utilizing the thermodynamic and kinetic information acquired from the aforementioned calculations. This model specifically targets the initial stages of β-d-xylopyranose pyrolysis in the high-pressure limit, aiming to gain a deeper understanding of its reaction kinetics. This approach establishes a systematic strategy for exploring reactive pathways, evaluating competing parallel reactions, and selectively accepting or discarding pathways based on the analysis. The findings suggest that acyclic d-xylose plays a significant role as an intermediary in the production of key pyrolytic compounds during the pyrolysis of xylose. These compounds include furfural, anhydro-d-xylopyranose, glycolaldehyde, and dihydrofuran-3(2H)-one.