Article
Multidisciplinary Sciences
Georgia Bradshaw, Mel O'Leary, Arthur S. F. Purser, Balder Villagomez-Bernabe, Cyrus Wyett, Frederick Currell, Marcus Webb
Summary: This paper presents a method for simulating inhomogeneous chemical kinetics by using a linear expansion of basis functions to describe the concentrations of interacting chemical species. The method efficiently propagates the coupled reaction and diffusion processes through time using tailor-made numerical methods. Illustrative calculations show the method's efficiency in modelling radiolysis in thin layers of water and solid interfaces. The method is also capable of solving problems with spherical symmetry and simulating solid-fluid interfaces.
SCIENTIFIC REPORTS
(2023)
Article
Materials Science, Multidisciplinary
Christian Marquardt, Alexander Paulheim, Manuel Hochheim, Thomas Bredow, Moritz Sokolowski
Summary: High-resolution laser spectroscopy was used to measure the homogeneous line profile of a single molecule adsorbed on a surface. The study focused on the prototype organic molecule PTCDA adsorbed on KCl thin epitaxial film on Ag(100). The narrow zero-phonon line shape was observed, and by understanding the single molecule line profile, a quantitative model based on surface defects was used to explain the inhomogeneous line profile of an ensemble of PTCDA molecules.
Article
Physics, Multidisciplinary
Yuval Scher, Shlomi Reuveni
Summary: This study reveals the reasons and characteristics of gated reactions through a unified approach, and demonstrates the exotic kinetics arising from molecular gating through case studies.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Electrical & Electronic
John L. Tsalamengas
Summary: This study investigates the oblique scattering of arbitrarily polarized plane waves from radially inhomogeneous and bianisotropic cylinders when all elements of the four constitutive tensors are non-zero. The analysis is based on an exact reformulation of Maxwell's equations as a second-kind linear Volterra matrix integral equation, with a discretization scheme using a high-order Nystrom method. The proposed algorithms have exponential convergence and can handle both single-layer and multilayer cylinders with continuous or sectionally continuous inhomogeneity profiles.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2021)
Article
Mathematics, Applied
Virginia Giorno, Amelia G. Nobile
Summary: In this paper, we study a time-inhomogeneous diffusion process obtained by applying the composition method to two Wiener processes. We also investigate the corresponding diffusion process restricted by a reflecting boundary in the zero-state. Additionally, we consider a special time-inhomogeneous diffusion process with discontinuous drift symmetric with respect to zero-state. Various numerical computations are performed in the presence of periodic noise intensity.
APPLIED MATHEMATICS AND COMPUTATION
(2023)
Article
Nanoscience & Nanotechnology
Irina Belova, Mohammad Afikuzzaman, Graeme E. Murch
Summary: The analysis of interdiffusion in multicomponent alloys is approached using a new mathematical method that fits composition profiles and determines interdiffusion coefficients. Small differences in composition profiles can lead to significant variations in interdiffusion coefficients. The new approach shows excellent performance in experimental results.
SCRIPTA MATERIALIA
(2021)
Article
Mathematics, Interdisciplinary Applications
O. Barrera
Summary: This paper presents a unified mathematical and computational framework for mechanics-coupled anomalous transport phenomena in porous media, discussing the impact of variable permeability on anomalous diffusion and the influence of a fractional pore pressure diffusion equation on diffusion transient phenomena. The research demonstrates the possibility of solving 3D consolidation problems of large scale structures by implementing the fractional pore pressure diffusion equation in a finite element framework with discretised fractional derivatives.
COMPUTATIONAL MECHANICS
(2021)
Article
Computer Science, Artificial Intelligence
Hang Yu, Aishan Liu, Gengchao Li, Jichen Yang, Chongzhi Zhang
Summary: PDA is a method that improves the robustness of DNNs by progressively injecting diverse adversarial noises during training. Compared to other strategies, DNNs trained with PDA achieve better general robustness against adversarial attacks, common corruptions, and clean images.
IEEE TRANSACTIONS ON IMAGE PROCESSING
(2021)
Article
Thermodynamics
Debabrata Das, Nanda Poddar, Subham Dhar, Rishi Raj Kairi, Kajal Kumar Mondal
Summary: This study deduced an analytical solution for the two-dimensional transport of solute concentration in a fluid between two parallel plates with homogeneous and first-order inhomogeneous reactions. The transverse concentration distribution was obtained using Mei's homogenization method up to a third-order approximation. The research showed that the Taylor dispersion coefficient decreases with increasing homogeneous and inhomogeneous reactions, leading to non-uniformity in the solute cloud's transverse distribution, and the centroid of the concentration cloud moves under different reaction conditions.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Electrical & Electronic
Ming-Yi You
Summary: This paper proposes a deep neural networks (DNNs) based approach for 2D direction finding in multiple frequencies. The approach is frequency-unified and capable of predicting direction of arrival (DoA) for multiple frequencies. The paper introduces a model output for 2D direction finding and suggests a label-dependent loss motivated by different Cramer-Rao Lower Bound (CRLB) of direction finding accuracy. An inhomogeneous angle and frequency partition strategy is also proposed for efficient implementation. Numerical investigations show that the proposed approach performs well in both ideal and nonideal scenarios, and demonstrates the added value of treating samples of different frequencies in a unified manner.
IEEE SENSORS JOURNAL
(2022)
Article
Astronomy & Astrophysics
Christian G. Boehmer, Erik Jensko
Summary: By proposing a new setup based on the original Einstein action, we can formulate modified gravity theories with second or fourth order field equations. Our theory is equivalent to the f(Q) gravity models, as well as capable of reproducing f(R) and f(T) gravity. Different from these theories, our approach emphasizes the importance of boundary terms in establishing the equivalence between them.
Article
Computer Science, Artificial Intelligence
Eran Dahan, Yosi Keller
Summary: This work proposes a deep learning-based approach for kin verification with a unified multi-task learning scheme, effectively utilizing small training sets. It introduces a novel method for fusing kin images embeddings and an adaptive sampling scheme to address the imbalance in datasets. Experimental results demonstrate its superiority over contemporary state-of-the-art kin verification results on various datasets.
IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE
(2021)
Review
Computer Science, Information Systems
Mingwen Yang, Zhiqiang Eric Zheng, Vijay Mookerjee, Hongyu Chen
Summary: This paper examines how firms manage their online ratings and the impact of review ratings on sales and profits in a competitive market. The study finds that firms need to exert more effort in managing ratings when profit margin is high or customers are highly sensitive to ratings. The controlled diffusion model developed in this study explains the coevolution of sales and ratings as a function of the response strategy chosen.
Article
Optics
Yousuf Aborahama, Mo Mojahedi
Summary: Designing optical fields with predetermined properties in source-free inhomogeneous media has been a long-sought goal due to its potential in various applications. A general framework based on the Helmholtz equation is provided to design optical fields with prechosen amplitude and phase. The analytical approach is verified through different techniques, demonstrating its validity in generating desired optical fields in various inhomogeneous media.
Article
Mechanics
S. Saha, E. Yariv
Summary: This study addresses the well-posed problem of a homogeneous phoretic swimmer with circular cross-section in two dimensions. By introducing a slight inhomogeneity, diffusio-osmosis is used to animate the phoretic motion. The singular problem associated with the scale disparity is analyzed using matched asymptotic expansions, which provide an implicit equation for the particle velocity. The velocity exhibits non-trivial dependence on the sign of the slip coefficient.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Biochemistry & Molecular Biology
Luis Fernando Mercier Franco, Pedro de Alcantara Pessoa Filho
Summary: The study introduces an extension using the Hill equation to describe anomalous ionization profiles, applied to five enzymes with different ionization states. The developed equation improves the description of enzymatic curves deviating from the bell curve predicted by the Henderson-Hasselbalch equation, regardless of the ionization scheme related to the active site.
APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
(2022)
Article
Thermodynamics
Qianhui Wu, Lei Ding, Lei Zhang, Jijiang Ge, Mohammad Azizur Rahman, Dominique Guerillot, Ioannis G. Economou
Summary: The feasibility of using polymer enhanced foam (PEF) for enhanced oil recovery (EOR) in strongly oil-wet and heterogeneous carbonate reservoirs was investigated. The study focused on the effect of polymer type, flow rate, and brine composition on the foam strength and stability. It was found that adding an associative polymer or a nonionic polymer to the foam greatly enhanced its strength and stability, leading to significant improvements in oil recovery efficiency. The study highlights the importance of the interactions between the polymer and surfactant in PEF behavior.
Article
Thermodynamics
Nefeli Novak, Georgios M. Kontogeorgis, Marcelo Castier, Ioannis G. Economou
Summary: In this study, the eSAFT-VR Mie equation of state is extended to low relative permittivity, non-aqueous solutions. Different relative permittivity relations and approaches for the characteristic diameters are investigated. Results show that a mole fraction based mixing rule for the relative permittivity yields the best extrapolation from aqueous to non-aqueous solutions.
FLUID PHASE EQUILIBRIA
(2023)
Article
Engineering, Chemical
Panagiotis Krokidas, Marcelle B. M. Spera, Lamprini G. Boutsika, Ioannis Bratsos, Georgia Charalambopoulou, Ioannis G. Economou, Theodore Steriotis
Summary: In this study, the researchers demonstrated how molecular-scale modifications of zeolitic-imidazolate frameworks (ZIFs) can greatly improve the CO2/CH4 separation performance of mixed-matrix membranes (MMMs) when used as additives. Through molecular simulations and experiments, they identified modified ZIF fillers that exhibit unprecedented CO2/CH4 separation performance, surpassing any reported MMM. This work highlights the effectiveness of ZIF nanoengineering in developing highly selective CO2 membranes.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Thermodynamics
Andre F. Gonsalves, Marcelo Castier, Luis F. M. Franco
Summary: In this work, the adsorption isotherms of carbon dioxide, methane, and propane on carbon slit pores are predicted using an alternative version of MPTA coupled with a global phase stability test. The results show that while the proposed methodology accurately correlates experimental data at temperatures above the critical temperature, significant deviations are observed when subcritical conditions are considered. Generally, the MPTA coupled with the Steele potential fails to reproduce the qualitative trend of the experimental isotherms, whereas the DRA potential provides good agreement, for some of the systems evaluated.
FLUID PHASE EQUILIBRIA
(2023)
Article
Thermodynamics
Ilias K. Nikolaidis, Romain Privat, Jean-Noel Jaubert, Ioannis G. Economou
Summary: This study assesses the performance of the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) using various mixing rules and regression parameters, based on a high-quality reference database. The model's ability to qualitatively reproduce experimental data is quantified using a performance indicator. The effects of induced-association and cross-association on the EoS are investigated, and the final optimized EoS is determined. The average mark for the optimized EoS is 9.3/20.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2023)
Article
Chemistry, Physical
Felipe M. Coelho, Luis F. M. Franco, Abbas Firoozabadi
Summary: This study systematically evaluates the thermodiffusion of the CO2-H2O mixture and its segregation in deep saline aquifers under geothermal gradients. It finds that at colder regions, CO2 accumulates, and the separation effect is more significant at lower temperatures. The Soret effect is more pronounced than gravity segregation, and CO2 concentrates in the top (colder region) under typical subsurface conditions.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Biographical-Item
Chemistry, Physical
Edward J. Maginn, Ioannis G. Economou, Randall Q. Snurr, Arup K. Chakraborty
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Chemistry, Physical
Angel D. Cortes Morales, Nikolaos Diamantonis, Ioannis G. Economou, Cornelis J. Peters, J. Ilja Siepmann
Summary: The behavior of binary systems containing a low-boiling compound and a high-boiling compound near the critical point of the low-boiling compound can be unexpected. Increasing the pressure near the critical temperature of the low-boiling compound and for compositions rich in the low-boiling compound may result in the crossing of dew-point and bubble-point curves multiple times. This phenomenon, known as double retrograde vaporization, has implications in oil field operations and gas transport through pipelines, but the underlying reasons for its occurrence are not well understood. Monte Carlo simulations were conducted to provide molecular insights into the fluid properties associated with double retrograde vaporization using the united-atom version of the TraPPE force field for a methane/n-butane mixture.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Chemistry, Physical
Noura Dawass, Manolis Vasileiadis, Loukas D. Peristeras, Konstantinos D. Papavasileiou, Ioannis G. Economou
Summary: Shale gas production is a rapidly growing sector in the oil and gas industry, and accurate prediction of its adsorption and transport is crucial for estimating production capacity. This study used molecular simulations to investigate the adsorption and diffusion of methane, ethane, and shale gas in a composite pore model representing heterogeneous shale formations. The addition of an inner slit pore significantly increased the adsorption of methane, and the saturation of the composite pore with methane occurred at a higher pressure than ethane. Carbon dioxide adsorption was not strongly affected by pressure, and its affinity to kerogen micropores was observed in all conditions. Diffusion coefficients were found to increase with the width of the empty slab inside the composite pore. The results provide insights into the adsorption mechanisms occurring inside the pore.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Thermodynamics
Andre F. Goncalves, Luis F. M. Franco, Marcelo Castier
Summary: In this study, we simulate the simultaneous centrifugation and adsorption processes in a centrifugal field. By minimizing the total Helmholtz energy of the system, the spatial distribution of binary and ternary mixtures of hydrocarbons, carbon dioxide, and hydrogen sulfide in a rotating packed bed is predicted.
FLUID PHASE EQUILIBRIA
(2023)
Review
Engineering, Chemical
Nefeli Novak, Georgios M. Kontogeorgis, Marcelo Castier, Ioannis G. Economou
Summary: This study focuses on the mixed-solvent electrolyte solutions and addresses the mean ionic activity coefficients, vapor-liquid equilibrium, and liquid-liquid equilibrium. The existing models and equations of state for electrolyte systems are reviewed, with emphasis on physical and electrolyte terms, relative static permittivity, and parameterization. A predictive model, eSAFT-VR Mie, is used to predict the activity coefficients, vapor-liquid equilibrium, and liquid-liquid equilibrium without any new adjustable parameters. The model shows excellent performance in predicting the activity coefficients and vapor-liquid equilibrium, while the prediction for liquid-liquid equilibrium is more challenging but has potential with accurate composition capturing.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Education, Scientific Disciplines
Luis Fernando Mercier Franco, Aline Carvalho da Costa, Ambrosio Florencio de Almeida Neto, Angela Maria Moraes, Elias Basile Tambourgi, Everson Alves Miranda, Guilherme Jose de Castilho, Gustavo Doubek, Jose Vicente Hallak Dangelo, Leonardo Vasconcelos Fregolente, Liliane Maria Ferrareso Lona, Lucimara Gaziola de la Torre, Luz Adriana Alvarez, Mariana Conceicao da Costa, Patricia Fazzio Martins Martinez, Roberta Ceriani, Roger Josef Zemp, Ronierik Pioli Vieira, Rubens Maciel Filho, Savio Souza Venancio Vianna, Sonia Maria Alves Bueno, Melissa Gurgel Adeodato Vieira, Raphael Soeiro Suppino
Summary: Engineering education is being asked to shift towards student-centered teaching and develop a competency-based curriculum that encompasses both technical and soft skills. This study presents a top-down methodology for designing such a curriculum and discusses the challenges of implementing and evaluating it. The newly developed curriculum for chemical engineering at the University of Campinas integrates real-life experiences and social responsibility to meet the needs of society.
EDUCATION FOR CHEMICAL ENGINEERS
(2023)
Article
Thermodynamics
Vitor P. Paixao, Luis F. M. Franco, Jose Vicente H. Dangelo
Summary: This study evaluated the possibility of using medium temperature saturated steam from a reactor cooling system as a heat source for generating electricity. Methanol and ethanol showed the best performance in the ORC configuration, and adding a recuperator improved the performance of dry fluids. Economic analysis revealed that net power generation is crucial for feasibility, with Case 1 achieving economic feasibility and methanol being the best working fluid.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Article
Chemistry, Physical
Panagiotis Krokidas, Stelios Karozis, Salvador Moncho, George Giannakopoulos, Edward N. Brothers, Michael E. Kainourgiakis, Ioannis G. Economou, Theodore A. Steriotis
Summary: This study uses machine learning to investigate the effect of pore structure on molecular diffusivity in metal organic frameworks (MOFs), providing new theoretical and methodological insights into molecular sieving.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)