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Analytic calculation of formation enthalpies directly from interatomic potentials for binary and ternary refractory metal systems

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Science China(Technological Sciences) 2010年第7期53卷 2015-2019页

作者： DAI Ye, LI JiaHao, CHE XingLai & LIU BaiXin Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. 1. Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

An analytic method is proposed to calculate the formation enthalpy directly from empirical n-body potential and applied to the binary and ternary systems consisting of the refractory metals Mo, Nb, Ta and W. It turns out that the calculated enthalpies are in overall agreement with experimental observations and some other theoretical calculations. Interestingly, it shows that the formation enthalpies of the ternary systems are significantly affected by those of the constituent binary systems.

关键词： n-body potential refractory materials ternary systems thermodynamic computations

CFD Analysis of Ship-to-Ship Hydrodynamic Interaction

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Journal of Marine Science and Application 2018年第1期17卷 21-37页

作者： A.D.Wnek Serge Sutulo C.Guedes Soares Centre for Marine Technology and Ocean Engineering(CENTEC) Instituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais1049-001 LisbonPortugal

A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code,and the results are compared with experimental data and with the results of a panel method *** ship models have been used in the interaction forces analysis:a tug and a tanker,advancing parallel to each other with different lateral distances and two different values of the fluid *** are carried out with four different flow models:inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface.A fair agreement was obtained with available experimental data and results obtained by panel *** influence of viscosity in the computations is found to be comparatively weak,while the wavemaking effects may be important,at small magnitude of the horizontal clearance.

关键词： Hydrodynamic interaction Computational fluid dynamics(CFD) Flow model Comparative computations Ship-to-ship interaction Shallow water

Understanding the Theory of Karp, Miller and Winograd

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Journal of Applied Mathematics and Physics 2024年第4期12卷 1203-1236页

作者： Athanasios I. Margaris Department of Digital Systems Gaiopolis Campus University of Thessaly Larissa Greece

The objective of this tutorial is to present the fundamental theory of Karp, Miller and Winograd, whose seminal paper laid the foundations regarding the systematic description of the organization of computations in systems of uniform recurrent equations by means of graph structures, via the definition of computability conditions and techniques for the construction of one-dimensional and multi-dimensional scheduling functions. Besides the description of this theory, the paper presents improvements and revisions made by other authors and furthermore, points out the differences regarding the conditions of causality and dependency between the general case of systems of recurrent equations and the special case of multiple nested loops.

关键词： Computability Scheduling computations Recurrent Equations

Spectroscopic Characterization, Molecular Modeling and DFT/TD-DFT/PCM Calculations of Novel Hydrogen-Bonded Charge Transfer Complex between Chloranilic Acid and 2-Amino-4,6-Dimethylpyridine

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Open Journal of Physical Chemistry 2020年第1期10卷 1-32页

作者： Khairia M. Al-Ahmary Fatimah A. Alshehri Faten M. Atlam Mohamed K. Awad University of Jeddah College of Science Department of Chemistry Jeddah Saudi Arabia Department of Chemistry Faculty of Science and Arts University of Bisha Alnamas Saudi Arabia Theoretical Applied Chemistry Unit (TACU) Chemistry Department Faculty of Science Tanta University Tanta Egypt

A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation.

关键词： 2-Amino-4 6-Dimethylpyridine Charge Transfer DFT Hydrogen Bond Molecular Modelling computations and Spectroscopy

Evolution of an Emerging Symmetric Quantum Cryptographic Algorithm

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Journal of Information Security 2015年第2期6卷 82-91页

作者： Omer K. Jasim Safia Abbas El-Sayed M. Horbaty Abdel-Badeeh M. Salem Computer Science Al-Ma’arif College University Anbar Iraq Faculty of Computer and Information Sciences Ain Shams University Cairo Egypt

With the rapid evolution of data exchange in network environments, information security has been the most important process for data storage and communication. In order to provide such information security, the confidentiality, data integrity, and data origin authentication must be verified based on cryptographic encryption algorithms. This paper presents a new emerging trend of modern symmetric encryption algorithm by development of the advanced encryption standard (AES) algorithm. The new development focuses on the integration between Quantum Key Distribution (QKD) and an enhanced version of AES. A new quantum symmetric encryption algorithm, which is abbreviated as Quantum-AES (QAES), is the output of such integration. QAES depends on generation of dynamic quantum S-Boxes (DQS-Boxes) based quantum cipher key, instead of the ordinary used static S-Boxes. Furthermore, QAES exploits the specific selected secret key generated from the QKD cipher using two different modes (online and off-line).

关键词： AES Encryption/Decryption Quantum computations QKD Symmetric Algorithm

Minimum Description Length Methods in Bayesian Model Selection: Some Applications

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Open Journal of Statistics 2013年第2期3卷 103-117页

作者： Mohan Delampady Statistics and Mathematics Unit Indian Statistical Institute Bangalore India

computations involved in Bayesian approach to practical model selection problems are usually very difficult. Computational simplifications are sometimes possible, but are not generally applicable. There is a large literature available on a methodology based on information theory called Minimum Description Length (MDL). It is described here how many of these techniques are either directly Bayesian in nature, or are very good objective approximations to Bayesian solutions. First, connections between the Bayesian approach and MDL are theoretically explored;thereafter a few illustrations are provided to describe how MDL can give useful computational simplifications.

关键词： Bayesian Analysis Model Selection Minimum Description Length Hierarchical Bayes Bayesian computations

Spin nature of genetic code

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Journal of Biophysical Chemistry 2013年第2期4卷 52-57页

作者： Alexander A. Tulub Vassily E. Stefanov Faculty of Biology and Soil Saint-Petersburg State University Saint Petersburg Russia School of Physics and Astronomy University of Manchester Manchester UK

Nature has developed codon as a tool to manipulate a two-electron spin symmetry (short-living electrons, forming a radical pair, arise from the Mg-bound nucleosidetriphosphate cleavage at the triplet/singlet (T/S) crossing), which permits or forbids further nucleotide synthesis (DNA/RNA) and the synthesis of proteins. The thesis is confirmed by conducting DFT:B3LYP (6-311G** basis set) computations (T/S potential energy surfaces) with the model system composed of the template (C-G-C-G-A nucleotide sequence) and the growing chain (G-C-G nucleotide sequence, DNA or RNA). The origin of codon is in hyperfine interaction between a single electron, transferred onto the template, and three 31P nuclei built into the phosphorus fragments of nucleotides. The nuclei, together with the polynucleotide structure, form a spiral twist that is homeomorphic to a triangle patch on the Poincare sphere. Each triangle has unique angle values depending on the nucleotide nature and their position in the codon. The patch tracing produces the Berry phase changing the electron spin orientation from “up” to “down”. The Berry phase accumulation proceeds around the (T/S) conical intersections (CIs). The CIs are a result of complementary recognition between nucleotide bases at distances exceeding the commonly accepted Watson-Crick pairing by 0.17 A. Upon changing spin symmetry, the DNA or RNA chain is allowed to elongate by attaching a newly coming nucleotide. Without complementary recognition between the bases, the chain stops its elongation. The Berry phase accumulation along the patch tracing explains the effect of Crick’s wobbling when the second nucleotide plays a primary role in recognition. The data is directly linked to creation of a quantum computing device.

关键词： Spintronics Nucleotides Genetic Code Quantum computations Berry’s Phase Hyperfine Coupling

A New Algorithm for Generalized Least Squares Factor Analysis with a Majorization Technique

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Open Journal of Statistics 2015年第3期5卷 165-172页

作者： Kohei Adachi Graduate School of Human Sciences Osaka University Osaka Japan

Factor analysis (FA) is a time-honored multivariate analysis procedure for exploring the factors underlying observed variables. In this paper, we propose a new algorithm for the generalized least squares (GLS) estimation in FA. In the algorithm, a majorization step and diagonal steps are alternately iterated until convergence is reached, where Kiers and ten Berge’s (1992) majorization technique is used for the former step, and the latter ones are formulated as minimizing simple quadratic functions of diagonal matrices. This procedure is named a majorizing-diagonal (MD) algorithm. In contrast to the existing gradient approaches, differential calculus is not used and only elmentary matrix computations are required in the MD algorithm. A simuation study shows that the proposed MD algorithm recovers parameters better than the existing algorithms.

关键词： Exploratory Factor Analysis Generalized Least Squares Estimation Matrix computations Majorization

Grayscale Mapping of Historically Irrigated LandsUsing GIS

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Journal of Geographic Information System 2012年第1期4卷 33-36页

作者： Thomas C. Turney 不详

This document describes the use of grayscale mapping and GIS for identification of historical irrigated lands. Historical irrigated lands form the basis for water rights—a private property right in New Mexico that is bought and sold on the open market. Identification of irrigated land on historical photography is both a science and an art. Grayscale mapping of historic black and white photographs can aid in the identification of irrigated lands. GIS allows historical images to be geo-referenced and area computations to be performed on polygons that define the irrigated lands.

关键词： GIS Geo-Referencing Images Water Rights Irrigation Area computations Grayscale Mapping