First-principles study of length dependence of conductance in alkanedithiols

NASA Astrophysics Data System (ADS)

Zhou, Y. X.; Jiang, F.; Chen, H.; Note, R.; Mizuseki, H.; Kawazoe, Y.

2008-01-01

Electronic transport properties of alkanedithiols are calculated by a first-principles method based on density functional theory and nonequilibrium Green's function formalism. At small bias, the I-V characteristics are linear and the resistances conform to the Magoga's exponential law. The calculated length-dependent decay constant γ which reflects the effect of internal molecular structure is in accordance with most experiments quantitatively. Also, the calculated effective contact resistance R0 is in good agreement with the results of repeatedly measuring molecule-electrode junctions [B. Xu and N. Tao, Science 301, 1221 (2003)].

Implementation and benchmark of a long-range corrected functional in the density functional based tight-binding method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lutsker, V.; Niehaus, T. A., E-mail: thomas.niehaus@physik.uni-regensburg.de; Aradi, B.

2015-11-14

Bridging the gap between first principles methods and empirical schemes, the density functional based tight-binding method (DFTB) has become a versatile tool in predictive atomistic simulations over the past years. One of the major restrictions of this method is the limitation to local or gradient corrected exchange-correlation functionals. This excludes the important class of hybrid or long-range corrected functionals, which are advantageous in thermochemistry, as well as in the computation of vibrational, photoelectron, and optical spectra. The present work provides a detailed account of the implementation of DFTB for a long-range corrected functional in generalized Kohn-Sham theory. We apply themore » method to a set of organic molecules and compare ionization potentials and electron affinities with the original DFTB method and higher level theory. The new scheme cures the significant overpolarization in electric fields found for local DFTB, which parallels the functional dependence in first principles density functional theory (DFT). At the same time, the computational savings with respect to full DFT calculations are not compromised as evidenced by numerical benchmark data.« less

Quantum probability ranking principle for ligand-based virtual screening.

PubMed

Al-Dabbagh, Mohammed Mumtaz; Salim, Naomie; Himmat, Mubarak; Ahmed, Ali; Saeed, Faisal

2017-04-01

Chemical libraries contain thousands of compounds that need screening, which increases the need for computational methods that can rank or prioritize compounds. The tools of virtual screening are widely exploited to enhance the cost effectiveness of lead drug discovery programs by ranking chemical compounds databases in decreasing probability of biological activity based upon probability ranking principle (PRP). In this paper, we developed a novel ranking approach for molecular compounds inspired by quantum mechanics, called quantum probability ranking principle (QPRP). The QPRP ranking criteria would make an attempt to draw an analogy between the physical experiment and molecular structure ranking process for 2D fingerprints in ligand based virtual screening (LBVS). The development of QPRP criteria in LBVS has employed the concepts of quantum at three different levels, firstly at representation level, this model makes an effort to develop a new framework of molecular representation by connecting the molecular compounds with mathematical quantum space. Secondly, estimate the similarity between chemical libraries and references based on quantum-based similarity searching method. Finally, rank the molecules using QPRP approach. Simulated virtual screening experiments with MDL drug data report (MDDR) data sets showed that QPRP outperformed the classical ranking principle (PRP) for molecular chemical compounds.

Quantum probability ranking principle for ligand-based virtual screening

NASA Astrophysics Data System (ADS)

Al-Dabbagh, Mohammed Mumtaz; Salim, Naomie; Himmat, Mubarak; Ahmed, Ali; Saeed, Faisal

2017-04-01

Chemical libraries contain thousands of compounds that need screening, which increases the need for computational methods that can rank or prioritize compounds. The tools of virtual screening are widely exploited to enhance the cost effectiveness of lead drug discovery programs by ranking chemical compounds databases in decreasing probability of biological activity based upon probability ranking principle (PRP). In this paper, we developed a novel ranking approach for molecular compounds inspired by quantum mechanics, called quantum probability ranking principle (QPRP). The QPRP ranking criteria would make an attempt to draw an analogy between the physical experiment and molecular structure ranking process for 2D fingerprints in ligand based virtual screening (LBVS). The development of QPRP criteria in LBVS has employed the concepts of quantum at three different levels, firstly at representation level, this model makes an effort to develop a new framework of molecular representation by connecting the molecular compounds with mathematical quantum space. Secondly, estimate the similarity between chemical libraries and references based on quantum-based similarity searching method. Finally, rank the molecules using QPRP approach. Simulated virtual screening experiments with MDL drug data report (MDDR) data sets showed that QPRP outperformed the classical ranking principle (PRP) for molecular chemical compounds.

Fast secant methods for the iterative solution of large nonsymmetric linear systems

NASA Technical Reports Server (NTRS)

Deuflhard, Peter; Freund, Roland; Walter, Artur

1990-01-01

A family of secant methods based on general rank-1 updates was revisited in view of the construction of iterative solvers for large non-Hermitian linear systems. As it turns out, both Broyden's good and bad update techniques play a special role, but should be associated with two different line search principles. For Broyden's bad update technique, a minimum residual principle is natural, thus making it theoretically comparable with a series of well known algorithms like GMRES. Broyden's good update technique, however, is shown to be naturally linked with a minimum next correction principle, which asymptotically mimics a minimum error principle. The two minimization principles differ significantly for sufficiently large system dimension. Numerical experiments on discretized partial differential equations of convection diffusion type in 2-D with integral layers give a first impression of the possible power of the derived good Broyden variant.

Teaching for Engagement: Part 2: Technology in the Service of Active Learning

ERIC Educational Resources Information Center

Hunter, William J.

2015-01-01

In the first piece in this series ("Teaching for Engagement: Part 1: Constructivist Principles, Case-Based Teaching, and Active Learning"), William Hunter sought to make the case that a wide range of teaching methods (e.g., case-based teaching, problem-based learning, anchored instruction) that share an intellectual grounding in…

Impact of first-principles properties of deuterium-tritium on inertial confinement fusion target designsa)

NASA Astrophysics Data System (ADS)

Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militzer, B.

2015-05-01

A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium-tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF "path" to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ˜2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.

Threshold secret sharing scheme based on phase-shifting interferometry.

PubMed

Deng, Xiaopeng; Shi, Zhengang; Wen, Wei

2016-11-01

We propose a new method for secret image sharing with the (3,N) threshold scheme based on phase-shifting interferometry. The secret image, which is multiplied with an encryption key in advance, is first encrypted by using Fourier transformation. Then, the encoded image is shared into N shadow images based on the recording principle of phase-shifting interferometry. Based on the reconstruction principle of phase-shifting interferometry, any three or more shadow images can retrieve the secret image, while any two or fewer shadow images cannot obtain any information of the secret image. Thus, a (3,N) threshold secret sharing scheme can be implemented. Compared with our previously reported method, the algorithm of this paper is suited for not only a binary image but also a gray-scale image. Moreover, the proposed algorithm can obtain a larger threshold value t. Simulation results are presented to demonstrate the feasibility of the proposed method.

Three-Dimensional Plasma-Based Stall Control Simulations with Coupled First-Principles Approaches

DTIC Science & Technology

2006-07-01

flow code, developed at the Computational Plasma Dynamics Laboratory at Kettering University. The method is based on a versatile finite-element ( FE ...McLaughlin, T., and Baughn, J., 2005. “Acoustic testing of the dielectric barrier dis- charge ( dbd ) plasma actuator”. AIAA Paper 2005-0565, Jan

Evaluation of the Laplace Integral. Classroom Notes

ERIC Educational Resources Information Center

Chen, Hongwei

2004-01-01

Based on the dominated convergence theorem and parametric differentiation, two different evaluations of the Laplace integral are displayed. This article presents two different proofs of (1) which may be of interest since they are based on principles within the realm of real analysis. The first method applies the dominated convergence theorem to…

Density functional theory calculations of III-N based semiconductors with mBJLDA

NASA Astrophysics Data System (ADS)

Gürel, Hikmet Hakan; Akıncı, Özden; Ünlü, Hilmi

2017-02-01

In this work, we present first principles calculations based on a full potential linear augmented plane-wave method (FP-LAPW) to calculate structural and electronic properties of III-V based nitrides such as GaN, AlN, InN in a zinc-blende cubic structure. First principles calculation using the local density approximation (LDA) and generalized gradient approximation (GGA) underestimate the band gap. We proposed a new potential called modified Becke-Johnson local density approximation (MBJLDA) that combines modified Becke-Johnson exchange potential and the LDA correlation potential to get better band gap results compared to experiment. We compared various exchange-correlation potentials (LSDA, GGA, HSE, and MBJLDA) to determine band gaps and structural properties of semiconductors. We show that using MBJLDA density potential gives a better agreement with experimental data for band gaps III-V nitrides based semiconductors.

Efficient Predictions of Excited State for Nanomaterials Using Aces 3 and 4

DTIC Science & Technology

2017-12-20

by first-principle methods in the software package ACES by using large parallel computers, growing tothe exascale. 15. SUBJECT TERMS Computer...modeling, excited states, optical properties, structure, stability, activation barriers first principle methods , parallel computing 16. SECURITY...2 Progress with new density functional methods

Predicting the electronic properties of aqueous solutions from first-principles

NASA Astrophysics Data System (ADS)

Schwegler, Eric; Pham, Tuan Anh; Govoni, Marco; Seidel, Robert; Bradforth, Stephen; Galli, Giulia

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum-mechanical methods. Yet it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. Here we propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, based on the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results for the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecular dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of their electronic properties, including excitation energies, of the solvent and solutes. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies. Part of this work was performed under the auspices of the U.S. Department of Energy at LLNL under Contract DE-AC52-07A27344.

First-principles study for the enhanced sulfur tolerance of Ni(1 1 1) surface alloyed with Pb

NASA Astrophysics Data System (ADS)

Zhang, Yanxing; Yang, Zongxian

2018-04-01

The adsorption of H2S, HS, S, H and the dissociation of H2S on the Ni2Pb/Ni (1 1 1) are systematically studied using the first-principles method based on density functional theory. It is found that H2S dissociation barriers are greatly increased by alloying with Pb atoms in the Ni(1 1 1) surface, while the barrier for H2S formation is greatly reduced. In addition, the adsorption of sulfur atom is weakened a lot. The results indicate that alloying with Pb may be a good way to increase the sulfur tolerance of Ni based anode catalysts of solid oxide fuel cells.

A recursively formulated first-order semianalytic artificial satellite theory based on the generalized method of averaging. Volume 1: The generalized method of averaging applied to the artificial satellite problem

NASA Technical Reports Server (NTRS)

Mcclain, W. D.

1977-01-01

A recursively formulated, first-order, semianalytic artificial satellite theory, based on the generalized method of averaging is presented in two volumes. Volume I comprehensively discusses the theory of the generalized method of averaging applied to the artificial satellite problem. Volume II presents the explicit development in the nonsingular equinoctial elements of the first-order average equations of motion. The recursive algorithms used to evaluate the first-order averaged equations of motion are also presented in Volume II. This semianalytic theory is, in principle, valid for a term of arbitrary degree in the expansion of the third-body disturbing function (nonresonant cases only) and for a term of arbitrary degree and order in the expansion of the nonspherical gravitational potential function.

Direct evaluation of free energy for large system through structure integration approach.

PubMed

Takeuchi, Kazuhito; Tanaka, Ryohei; Yuge, Koretaka

2015-09-30

We propose a new approach, 'structure integration', enabling direct evaluation of configurational free energy for large systems. The present approach is based on the statistical information of lattice. Through first-principles-based simulation, we find that the present method evaluates configurational free energy accurately in disorder states above critical temperature.

Improved estimation of parametric images of cerebral glucose metabolic rate from dynamic FDG-PET using volume-wise principle component analysis

NASA Astrophysics Data System (ADS)

Dai, Xiaoqian; Tian, Jie; Chen, Zhe

2010-03-01

Parametric images can represent both spatial distribution and quantification of the biological and physiological parameters of tracer kinetics. The linear least square (LLS) method is a well-estimated linear regression method for generating parametric images by fitting compartment models with good computational efficiency. However, bias exists in LLS-based parameter estimates, owing to the noise present in tissue time activity curves (TTACs) that propagates as correlated error in the LLS linearized equations. To address this problem, a volume-wise principal component analysis (PCA) based method is proposed. In this method, firstly dynamic PET data are properly pre-transformed to standardize noise variance as PCA is a data driven technique and can not itself separate signals from noise. Secondly, the volume-wise PCA is applied on PET data. The signals can be mostly represented by the first few principle components (PC) and the noise is left in the subsequent PCs. Then the noise-reduced data are obtained using the first few PCs by applying 'inverse PCA'. It should also be transformed back according to the pre-transformation method used in the first step to maintain the scale of the original data set. Finally, the obtained new data set is used to generate parametric images using the linear least squares (LLS) estimation method. Compared with other noise-removal method, the proposed method can achieve high statistical reliability in the generated parametric images. The effectiveness of the method is demonstrated both with computer simulation and with clinical dynamic FDG PET study.

Analyzing the equilibrium states of a quasi-neutral spatially inhomogeneous system of charges above a liquid dielectric film based on the first principles of quantum statistics

NASA Astrophysics Data System (ADS)

Lytvynenko, D. M.; Slyusarenko, Yu V.

2017-08-01

A theory of quasi-neutral equilibrium states of charges above a liquid dielectric surface is developed. This theory is based on the first principles of quantum statistics for systems comprising many identical particles. The proposed approach involves applying the variational principle, modified for the considered systems, and the Thomas-Fermi model. In the terms of the developed theory self-consistency equations are obtained. These equations provide the relation between the main parameters describing the system: the potential of the static electric field, the distribution function of charges and the surface profile of the liquid dielectric. The equations are used to study the phase transition in the system to a spatially periodic state. The proposed method can be applied in analyzing the properties of the phase transition in the system in relation to the spatially periodic states of wave type. Using the analytical and numerical methods, we perform a detailed study of the dependence of the critical parameters of such a phase transition on the thickness of the liquid dielectric film. Some stability criteria for the new asymmetric phase of the studied system are discussed.

A coupled mode formulation by reciprocity and a variational principle

NASA Technical Reports Server (NTRS)

Chuang, Shun-Lien

1987-01-01

A coupled mode formulation for parallel dielectric waveguides is presented via two methods: a reciprocity theorem and a variational principle. In the first method, a generalized reciprocity relation for two sets of field solutions satisfying Maxwell's equations and the boundary conditions in two different media, respectively, is derived. Based on the generalized reciprocity theorem, the coupled mode equations can then be formulated. The second method using a variational principle is also presented for a general waveguide system which can be lossy. The results of the variational principle can also be shown to be identical to those from the reciprocity theorem. The exact relations governing the 'conventional' and the new coupling coefficients are derived. It is shown analytically that the present formulation satisfies the reciprocity theorem and power conservation exactly, while the conventional theory violates the power conservation and reciprocity theorem by as much as 55 percent and the Hardy-Streifer (1985, 1986) theory by 0.033 percent, for example.

Optical absorption in disordered monolayer molybdenum disulfide

NASA Astrophysics Data System (ADS)

Ekuma, C. E.; Gunlycke, D.

2018-05-01

We explore the combined impact of sulfur vacancies and electronic interactions on the optical properties of monolayer MoS2. First, we present a generalized Anderson-Hubbard Hamiltonian that accounts for both randomly distributed sulfur vacancies and the presence of dielectric screening within the material. Second, we parametrize this energy-dependent Hamiltonian from first-principles calculations based on density functional theory and the Green's function and screened Coulomb (GW) method. Third, we apply a first-principles-based many-body typical medium method to determine the single-particle electronic structure. Fourth, we solve the Bethe-Salpeter equation to obtain the charge susceptibility χ with its imaginary part being related to the absorbance A . Our results show that an increased vacancy concentration leads to decreased absorption both in the band continuum and from exciton states within the band gap. We also observe increased absorption below the band-gap threshold and present an expression, which describes Lifshitz tails, in excellent qualitative agreement with our numerical calculations. This latter increased absorption in the 1.0 -2.5 eV range makes defect engineering of potential interest for solar cell applications.

The fluid dynamic approach to equidistribution methods for grid generation and adaptation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delzanno, Gian Luca; Finn, John M

2009-01-01

The equidistribution methods based on L{sub p} Monge-Kantorovich optimization [Finn and Delzanno, submitted to SISC, 2009] and on the deformation [Moser, 1965; Dacorogna and Moser, 1990, Liao and Anderson, 1992] method are analyzed primarily in the context of grid generation. It is shown that the first class of methods can be obtained from a fluid dynamic formulation based on time-dependent equations for the mass density and the momentum density, arising from a variational principle. In this context, deformation methods arise from a fluid formulation by making a specific assumption on the time evolution of the density (but with some degreemore » of freedom for the momentum density). In general, deformation methods do not arise from a variational principle. However, it is possible to prescribe an optimal deformation method, related to L{sub 1} Monge-Kantorovich optimization, by making a further assumption on the momentum density. Some applications of the L{sub p} fluid dynamic formulation to imaging are also explored.« less

Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport.

PubMed

Xie, Hang; Kwok, Yanho; Jiang, Feng; Zheng, Xiao; Chen, GuanHua

2014-10-28

Based on the complex absorbing potential (CAP) method, a Lorentzian expansion scheme is developed to express the self-energy. The CAP-based Lorentzian expansion of self-energy is employed to solve efficiently the Liouville-von Neumann equation of one-electron density matrix. The resulting method is applicable for both tight-binding and first-principles models and is used to simulate the transient currents through graphene nanoribbons and a benzene molecule sandwiched between two carbon-atom chains.

Optical Absorption in Molecular Crystals from Time-Dependent Density Functional Theory

DTIC Science & Technology

2017-04-18

fundamental gap but there is little effect on the optical spectra. We therefore believe that the method is robust and can be used for studies of... quantitative DFT- based prediction of excited-state properties in molecu- lar solids.[28, 29] In this approach, one first computes the underlying gas...gradient ap- proximation (GGA). In some cases , the fraction of SR Fock exchange, α, can be determined from first-principles based on satisfaction of

Astrophysical reaction rates from a symmetry-informed first-principles perspective

NASA Astrophysics Data System (ADS)

Dreyfuss, Alison; Launey, Kristina; Baker, Robert; Draayer, Jerry; Dytrych, Tomas

2017-01-01

With a view toward a new unified formalism for studying bound and continuum states in nuclei, to understand stellar nucleosynthesis from a fully ab initio perspective, we studied the nature of surface α-clustering in 20Ne by considering the overlap of symplectic states with cluster-like states. We compute the spectroscopic amplitudes and factors, α-decay width, and absolute resonance strength - characterizing major contributions to the astrophysical reaction rate through a low-lying 1- resonant state in 20Ne. As a next step, we consider a fully microscopic treatment for the n+4 He system, based on the successful first-principles No-Core Shell Model/Resonating Group Method (NCSM/RGM) for light nuclei, but with the capability to reach intermediate-mass nuclei. The new model takes advantage of the symmetry-based concept central to the Symmetry-Adapted No-Core Shell Model (SA-NCSM) to reduce computational complexity in physically-informed and methodical way, with sights toward first-principles calculations of rates for important astrophysical reactions, such as the 23 Al(p , γ) 24 Si reaction, believed to have a strong influence on X-ray burst light curves. Supported by the U.S. NSF (OCI-0904874, ACI -1516338) and the U.S. DOE (DE-SC0005248), and benefitted from computing resources provided by Blue Waters and the LSU Center for Computation & Technology.

Advanced characterization of lithium battery materials with positrons

NASA Astrophysics Data System (ADS)

Barbiellini, Bernardo; Kuriplach, Jan

2017-01-01

Cathode materials are crucial to improved battery performance, in part because there are not yet materials that can maintain high power and stable cycling with a capacity comparable to that of anode materials. Our parameter-free, gradient-corrected model for electron-positron correlations predicts that spectroscopies based on positron annihilation can be deployed to study the effect of lithium intercalation in the oxide matrix of the cathode. The positron characteristics in oxides can be reliably computed using methods based on first-principles. Thus, we can enable a fundamental characterization of lithium battery materials involving positron annihilation spectroscopy and first-principles calculations. The detailed information one can extract from positron experiments could be useful for understanding and optimizing both battery materials and bi-functional catalysts for oxygen reduction and evolution.

The problem of 'thick in status, thin in content' in Beauchamp and Childress' principlism.

PubMed

Lee, Marvin J H

2010-09-01

For many, Thomas Beauchamp and James Childress have elaborated moral reasoning by using the four principles whereby all substantive problems of medical ethics (and of ethics more generally) can be properly analysed and cogent philosophical solutions for the problems can be found. It seems that their 'principlism' gets updated, with better features being added during the course of the six editions of Principles of Biomedical Ethics. Nonetheless, Beauchamp and Childress seem to have been losing their way when it comes to the common-morality justification, which is the epistemological (and perhaps metaphysical) backbone of their method, and this is shown more vividly in their most recent (2009) edition of Principles of Biomedical Ethics. The author points out what he calls the problem of 'thick in status, thin in content' in principlism. The problem exists because principlism cannot adequately explain how the prescriptive sense of common morality it supports is consistent with the existence of what Beauchamp and Childress call the 'legitimate moral diversity in the world'. Because of this problem, first, the practical end that principlism allegedly accomplishes (ie, providing practical moral guidelines in a relatively 'thick' content, based on common morality) is frustrated, and, second, principlism makes itself the method of common morality de jure and of moral pluralism de facto.

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, S. X., E-mail: shu@lle.rochester.edu; Goncharov, V. N.; Boehly, T. R.

2015-05-15

A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into accountmore » in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κ{sub QMD}), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ∼2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.« less

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

DOE PAGES

Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; ...

2015-04-20

In this study, a comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximatelymore » taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (K QMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of –2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.« less

Site preference of alloying elements in DO22-Ni3V phase: Phase-field and first-principles study

NASA Astrophysics Data System (ADS)

Zhang, Ding-Ni; Shangguan, Qian-Qian; Liu, Fu; Zhang, Ming-Yi

2015-07-01

Site preference of alloying elements in DO22-Ni3V phase was investigated using phase-field and first-principles method. The concentrations of alloying elements on sublattices of DO22-Ni3V phase were quantitatively studied using phase-field model based on microscopic diffusion equations. The phase-field computation results demonstrate that the concentration differences of alloying elements on the NiI and NiII site are attributed to the coordination environment difference. Host atoms Ni and substitutional ternary additions Al prefer to occupy NiI site. Antisite atoms V show site preference on the NiII site. Further reason of site preference of alloying elements on the two different Ni sites were studied using first-principles method to calculate the electronic structure of DO22-Ni3V phase. Calculation of density of states, orbitals population and charge population of the optimized Ni3V structure found that the electronic structures of NiI and NiII sites are different. Electronic structure difference, which is caused by coordination environment difference, is the essential reason for site selectivity behaviors of alloying elements on NiI and NiII sites.

Understanding integrated care: a comprehensive conceptual framework based on the integrative functions of primary care

PubMed Central

Valentijn, Pim P.; Schepman, Sanneke M.; Opheij, Wilfrid; Bruijnzeels, Marc A.

2013-01-01

Introduction Primary care has a central role in integrating care within a health system. However, conceptual ambiguity regarding integrated care hampers a systematic understanding. This paper proposes a conceptual framework that combines the concepts of primary care and integrated care, in order to understand the complexity of integrated care. Methods The search method involved a combination of electronic database searches, hand searches of reference lists (snowball method) and contacting researchers in the field. The process of synthesizing the literature was iterative, to relate the concepts of primary care and integrated care. First, we identified the general principles of primary care and integrated care. Second, we connected the dimensions of integrated care and the principles of primary care. Finally, to improve content validity we held several meetings with researchers in the field to develop and refine our conceptual framework. Results The conceptual framework combines the functions of primary care with the dimensions of integrated care. Person-focused and population-based care serve as guiding principles for achieving integration across the care continuum. Integration plays complementary roles on the micro (clinical integration), meso (professional and organisational integration) and macro (system integration) level. Functional and normative integration ensure connectivity between the levels. Discussion The presented conceptual framework is a first step to achieve a better understanding of the inter-relationships among the dimensions of integrated care from a primary care perspective. PMID:23687482

Pushing the frontiers of first-principles based computer simulations of chemical and biological systems.

PubMed

Brunk, Elizabeth; Ashari, Negar; Athri, Prashanth; Campomanes, Pablo; de Carvalho, F Franco; Curchod, Basile F E; Diamantis, Polydefkis; Doemer, Manuel; Garrec, Julian; Laktionov, Andrey; Micciarelli, Marco; Neri, Marilisa; Palermo, Giulia; Penfold, Thomas J; Vanni, Stefano; Tavernelli, Ivano; Rothlisberger, Ursula

2011-01-01

The Laboratory of Computational Chemistry and Biochemistry is active in the development and application of first-principles based simulations of complex chemical and biochemical phenomena. Here, we review some of our recent efforts in extending these methods to larger systems, longer time scales and increased accuracies. Their versatility is illustrated with a diverse range of applications, ranging from the determination of the gas phase structure of the cyclic decapeptide gramicidin S, to the study of G protein coupled receptors, the interaction of transition metal based anti-cancer agents with protein targets, the mechanism of action of DNA repair enzymes, the role of metal ions in neurodegenerative diseases and the computational design of dye-sensitized solar cells. Many of these projects are done in collaboration with experimental groups from the Institute of Chemical Sciences and Engineering (ISIC) at the EPFL.

Success through Identification and Curriculum Change.

ERIC Educational Resources Information Center

Sapulpa Public Schools, OK.

One of the programs included in "Effective Reading Programs...," this program is based on the principle of early identification of students' strengths and weaknesses and the development of individualized methods to correct the weaknesses and emphasize the strengths. The program, begun in 1972, serves 749 kindergarten and first-grade…

Proton transfer from water to ketyl radical anion: Assessment of critical size of hydrated cluster and free energy barrier in solution from first principles simulations

NASA Astrophysics Data System (ADS)

Biswas, Sohag; Dasgupta, Teesta; Mallik, Bhabani S.

2016-09-01

We present the reactivity of an organic intermediate by studying the proton transfer process from water to ketyl radical anion using gas phase electronic structure calculations and the metadynamics method based first principles molecular dynamics (FPMD) simulations. Our results indicate that during the micro solvation of anion by water molecules systematically, the presence of minimum three water molecules in the gas phase cluster is sufficient to observe the proton transfer event. The analysis of trajectories obtained from initial FPMD simulation of an aqueous solution of the anion does not show any evident of complete transfer of the proton from water. The cooperativity of water molecules and the relatively weak anion-water interaction in liquid state prohibit the full release of the proton. Using biasing potential through first principles metadynamics simulations, we report the observation of proton transfer reaction from water to ketyl radical anion with a barrier height of 16.0 kJ/mol.

Lax-Friedrichs sweeping scheme for static Hamilton-Jacobi equations

NASA Astrophysics Data System (ADS)

Kao, Chiu Yen; Osher, Stanley; Qian, Jianliang

2004-05-01

We propose a simple, fast sweeping method based on the Lax-Friedrichs monotone numerical Hamiltonian to approximate viscosity solutions of arbitrary static Hamilton-Jacobi equations in any number of spatial dimensions. By using the Lax-Friedrichs numerical Hamiltonian, we can easily obtain the solution at a specific grid point in terms of its neighbors, so that a Gauss-Seidel type nonlinear iterative method can be utilized. Furthermore, by incorporating a group-wise causality principle into the Gauss-Seidel iteration by following a finite group of characteristics, we have an easy-to-implement, sweeping-type, and fast convergent numerical method. However, unlike other methods based on the Godunov numerical Hamiltonian, some computational boundary conditions are needed in the implementation. We give a simple recipe which enforces a version of discrete min-max principle. Some convergence analysis is done for the one-dimensional eikonal equation. Extensive 2-D and 3-D numerical examples illustrate the efficiency and accuracy of the new approach. To our knowledge, this is the first fast numerical method based on discretizing the Hamilton-Jacobi equation directly without assuming convexity and/or homogeneity of the Hamiltonian.

Retrieval of spheroid particle size distribution from spectral extinction data in the independent mode using PCA approach

NASA Astrophysics Data System (ADS)

Tang, Hong; Lin, Jian-Zhong

2013-01-01

An improved anomalous diffraction approximation (ADA) method is presented for calculating the extinction efficiency of spheroids firstly. In this approach, the extinction efficiency of spheroid particles can be calculated with good accuracy and high efficiency in a wider size range by combining the Latimer method and the ADA theory, and this method can present a more general expression for calculating the extinction efficiency of spheroid particles with various complex refractive indices and aspect ratios. Meanwhile, the visible spectral extinction with varied spheroid particle size distributions and complex refractive indices is surveyed. Furthermore, a selection principle about the spectral extinction data is developed based on PCA (principle component analysis) of first derivative spectral extinction. By calculating the contribution rate of first derivative spectral extinction, the spectral extinction with more significant features can be selected as the input data, and those with less features is removed from the inversion data. In addition, we propose an improved Tikhonov iteration method to retrieve the spheroid particle size distributions in the independent mode. Simulation experiments indicate that the spheroid particle size distributions obtained with the proposed method coincide fairly well with the given distributions, and this inversion method provides a simple, reliable and efficient method to retrieve the spheroid particle size distributions from the spectral extinction data.

Identification of F impurities in F-doped ZnO by synchrotron X-ray absorption near edge structures

NASA Astrophysics Data System (ADS)

Na-Phattalung, Sutassana; Limpijumnong, Sukit; Min, Chul-Hee; Cho, Deok-Yong; Lee, Seung-Ran; Char, Kookrin; Yu, Jaejun

2018-04-01

Synchrotron X-ray absorption near edge structure (XANES) measurements of F K-edge in conjunction with first-principles calculations are used to identify the local structure of the fluorine (F) atom in F-doped ZnO. The ZnO film was grown by pulsed laser deposition with an Nd:YAG laser, and an oxyfluoridation method was used to introduce F ions into the ZnO films. The measured XANES spectrum of the sample was compared against the first-principles XANES calculations based on various models for local atomic structures surrounding F atoms. The observed spectral features are attributed to ZnF2 and FO defects in wurtzite bulk ZnO.

First-Principles Framework to Compute Sum-Frequency Generation Vibrational Spectra of Semiconductors and Insulators.

PubMed

Wan, Quan; Galli, Giulia

2015-12-11

We present a first-principles framework to compute sum-frequency generation (SFG) vibrational spectra of semiconductors and insulators. The method is based on density functional theory and the use of maximally localized Wannier functions to compute the response to electric fields, and it includes the effect of electric field gradients at surfaces. In addition, it includes quadrupole contributions to SFG spectra, thus enabling the verification of the dipole approximation, whose validity determines the surface specificity of SFG spectroscopy. We compute the SFG spectra of ice I_{h} basal surfaces and identify which spectra components are affected by bulk contributions. Our results are in good agreement with experiments at low temperature.

Position Papers for the First Workshop on Principles and Practice of Constraint Programming Held in Newport, Rhode Island on April 28-30, 1993

DTIC Science & Technology

1993-04-30

There are alternative methods to MBB’s, based on decomposition of space into disjoint cells. These include uniform grid method [Fr84], quadtree-based...space. The IIn grid and quadtree methods there is a trade off between the resolution of the cells (and thus quantity of the cells) and the effectiveness...Mathematics, 13, pp. 221-229, 1983. 9 IFr84] W.R. Franklin, Adaptive grids for geometric operations, Cartographica 21, 2 g 3, pp. 160-167, 1984. (Gun87

First-Principles Prediction of Thermodynamically Stable Two-Dimensional Electrides

DOE PAGES

Ming, Wenmei; Yoon, Mina; Univ. of Tennessee, Knoxville, TN; ...

2016-10-21

Two-dimensional (2D) electrides, emerging as a new type of layered material whose electrons are confined in interlayer spaces instead of at atomic proximities, are receiving interest for their high performance in various (opto)electronics and catalytic applications. Experimentally, however, 2D electrides have been only found in a couple of layered nitrides and carbides. We report new thermodynamically stable alkaline-earth based 2D electrides by using a first-principles global structure optimization method, phonon spectrum analysis, and molecular dynamics simulation. The method was applied to binary compounds consisting of alkaline-earth elements as cations and group VA, VIA, or VIIA nonmetal elements as anions. Wemore » also revealed that the stability of a layered 2D electride structure is closely related to the cation/anion size ratio; stable 2D electrides possess a sufficiently large cation/anion size ratio to minimize electrostatic energy among cations, anions, and anionic electrons. This work demonstrates a new avenue to the discovery of thermodynamically stable 2D electrides beyond experimental material databases and provides new insight into the principles of electride design.« less

Enhancing the Student Experience of Laboratory Practicals through Digital Video Guides

ERIC Educational Resources Information Center

Croker, Karen; Andersson, Holger; Lush, David; Prince, Rob; Gomez, Stephen

2010-01-01

Laboratory-based learning allows students to experience bioscience principles first hand. In our experience, practical content and equipment may have changed over time, but teaching methods largely remain the same, typically involving; whole class introduction with a demonstration, students emulating the demonstration in small groups, gathering…

First-principles simulation of the optical response of bulk and thin-film α-quartz irradiated with an ultrashort intense laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Kyung-Min; Min Kim, Chul; Moon Jeong, Tae, E-mail: jeongtm@gist.ac.kr

A computational method based on a first-principles multiscale simulation has been used for calculating the optical response and the ablation threshold of an optical material irradiated with an ultrashort intense laser pulse. The method employs Maxwell's equations to describe laser pulse propagation and time-dependent density functional theory to describe the generation of conduction band electrons in an optical medium. Optical properties, such as reflectance and absorption, were investigated for laser intensities in the range 10{sup 10} W/cm{sup 2} to 2 × 10{sup 15} W/cm{sup 2} based on the theory of generation and spatial distribution of the conduction band electrons. The method was applied tomore » investigate the changes in the optical reflectance of α-quartz bulk, half-wavelength thin-film, and quarter-wavelength thin-film and to estimate their ablation thresholds. Despite the adiabatic local density approximation used in calculating the exchange–correlation potential, the reflectance and the ablation threshold obtained from our method agree well with the previous theoretical and experimental results. The method can be applied to estimate the ablation thresholds for optical materials, in general. The ablation threshold data can be used to design ultra-broadband high-damage-threshold coating structures.« less

Stiffness Parameter Design of Suspension Element of Under-Chassis-Equipment for A Rail Vehicle

NASA Astrophysics Data System (ADS)

Ma, Menglin; Wang, Chengqiang; Deng, Hai

2017-06-01

According to the frequency configuration requirements of the vibration of railway under-chassis-equipment, the three- dimension stiffness of the suspension elements of under-chassis-equipment is designed based on the static principle and dynamics principle. The design results of the concrete engineering case show that, compared with the design method based on the static principle, the three- dimension stiffness of the suspension elements designed by the dynamic principle design method is more uniform. The frequency and decoupling degree analysis show that the calculation frequency of under-chassis-equipment under the two design methods is basically the same as the predetermined frequency. Compared with the design method based on the static principle, the design method based on the dynamic principle is adopted. The decoupling degree can be kept high, and the coupling vibration of the corresponding vibration mode can be reduced effectively, which can effectively reduce the fatigue damage of the key parts of the hanging element.

Consensus methods: review of original methods and their main alternatives used in public health

PubMed Central

Bourrée, Fanny; Michel, Philippe; Salmi, Louis Rachid

2008-01-01

Summary Background Consensus-based studies are increasingly used as decision-making methods, for they have lower production cost than other methods (observation, experimentation, modelling) and provide results more rapidly. The objective of this paper is to describe the principles and methods of the four main methods, Delphi, nominal group, consensus development conference and RAND/UCLA, their use as it appears in peer-reviewed publications and validation studies published in the healthcare literature. Methods A bibliographic search was performed in Pubmed/MEDLINE, Banque de Données Santé Publique (BDSP), The Cochrane Library, Pascal and Francis. Keywords, headings and qualifiers corresponding to a list of terms and expressions related to the consensus methods were searched in the thesauri, and used in the literature search. A search with the same terms and expressions was performed on Internet using the website Google Scholar. Results All methods, precisely described in the literature, are based on common basic principles such as definition of subject, selection of experts, and direct or remote interaction processes. They sometimes use quantitative assessment for ranking items. Numerous variants of these methods have been described. Few validation studies have been implemented. Not implementing these basic principles and failing to describe the methods used to reach the consensus were both frequent reasons contributing to raise suspicion regarding the validity of consensus methods. Conclusion When it is applied to a new domain with important consequences in terms of decision making, a consensus method should be first validated. PMID:19013039

System and method for controlling an engine based on ammonia storage in multiple selective catalytic reduction catalysts

DOEpatents

Sun, MIn; Perry, Kevin L.

2015-11-20

A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Research on Sustainable Development Level Evaluation of Resource-based Cities Based on Shapely Entropy and Chouqet Integral

NASA Astrophysics Data System (ADS)

Zhao, Hui; Qu, Weilu; Qiu, Weiting

2018-03-01

In order to evaluate sustainable development level of resource-based cities, an evaluation method with Shapely entropy and Choquet integral is proposed. First of all, a systematic index system is constructed, the importance of each attribute is calculated based on the maximum Shapely entropy principle, and then the Choquet integral is introduced to calculate the comprehensive evaluation value of each city from the bottom up, finally apply this method to 10 typical resource-based cities in China. The empirical results show that the evaluation method is scientific and reasonable, which provides theoretical support for the sustainable development path and reform direction of resource-based cities.

Effect of train carbody's parameters on vertical bending stiffness performance

NASA Astrophysics Data System (ADS)

Yang, Guangwu; Wang, Changke; Xiang, Futeng; Xiao, Shoune

2016-10-01

Finite element analysis(FEA) and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it's stiffness is calculated with series principle, it's cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody's design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

First-principles study of complex material systems

NASA Astrophysics Data System (ADS)

He, Lixin

This thesis covers several topics concerning the study of complex materials systems by first-principles methods. It contains four chapters. A brief, introductory motivation of this work will be given in Chapter 1. In Chapter 2, I will give a short overview of the first-principles methods, including density-functional theory (DFT), planewave pseudopotential methods, and the Berry-phase theory of polarization in crystallines insulators. I then discuss in detail the locality and exponential decay properties of Wannier functions and of related quantities such as the density matrix, and their application in linear-scaling algorithms. In Chapter 3, I investigate the interaction of oxygen vacancies and 180° domain walls in tetragonal PbTiO3 using first-principles methods. Our calculations indicate that the oxygen vacancies have a lower formation energy in the domain wall than in the bulk, thereby confirming the tendency of these defects to migrate to, and pin, the domain walls. The pinning energies are reported for each of the three possible orientations of the original Ti--O--Ti bonds, and attempts to model the results with simple continuum models are discussed. CaCu3Ti4O12 (CCTO) has attracted a lot of attention recently because it was found to have an enormous dielectric response over a very wide temperature range. In Chapter 4, I study the electronic and lattice structure, and the lattice dynamical properties, of this system. Our first-principles calculations together with experimental results point towards an extrinsic mechanism as the origin of the unusual dielectric response.

Electronic and structural aspects of p450-mediated drug metabolism.

PubMed

Lewis, David F V; Ito, Yuko; Lake, Brian G

2009-04-01

From a consideration of first principles for enzymes kinetics, we have employed theoretical methods which enable one to analyse the kinetics of cytochrome P450-mediated reactions which have been based on the known physicochemical principles underlying the majority of chemical or enzymatic reactions. A comparison is made between the correlation equations produced from the QSAR analysis of experimental P450 reaction rate data and those obtained from first principles, where there appears to be a generally satisfactory concordance between the two procedures. In this respect, we have developed expressions based on standard reaction kinetics theory which incorporate the Eyring and Marcus relationships. The analysis of P450-catalyzed reaction rates is elaborated to encompass a treatment of metabolic clearance, and satisfactory correlations are obtained with literature values for both intrinsic clearance and whole body clearance in terms of compound lipophilicity derived from log P data, where P is the octanol/water partition coefficient. The importance of ionization potential as a factor in the overall catalytic turnover of P450-mediated reactions is noted, especially in combination with the lipophilicity parameter, log P.

How to Compute Electron Ionization Mass Spectra from First Principles.

PubMed

Bauer, Christoph Alexander; Grimme, Stefan

2016-06-02

The prediction of electron ionization (EI) mass spectra (MS) from first principles has been a major challenge for quantum chemistry (QC). The unimolecular reaction space grows rapidly with increasing molecular size. On the one hand, statistical models like Eyring's quasi-equilibrium theory and Rice-Ramsperger-Kassel-Marcus theory have provided valuable insight, and some predictions and quantitative results can be obtained from such calculations. On the other hand, molecular dynamics-based methods are able to explore automatically the energetically available regions of phase space and thus yield reaction paths in an unbiased way. We describe in this feature article the status of both methodologies in relation to mass spectrometry for small to medium sized molecules. We further present results obtained with the QCEIMS program developed in our laboratory. Our method, which incorporates stochastic and dynamic elements, has been a significant step toward the reliable routine calculation of EI mass spectra.

Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

NASA Astrophysics Data System (ADS)

Gustafsson, Alexander; Okabayashi, Norio; Peronio, Angelo; Giessibl, Franz J.; Paulsson, Magnus

2017-08-01

We describe a first-principles method to calculate scanning tunneling microscopy (STM) images, and compare the results to well-characterized experiments combining STM with atomic force microscopy (AFM). The theory is based on density functional theory with a localized basis set, where the wave functions in the vacuum gap are computed by propagating the localized-basis wave functions into the gap using a real-space grid. Constant-height STM images are computed using Bardeen's approximation method, including averaging over the reciprocal space. We consider copper adatoms and single CO molecules adsorbed on Cu(111), scanned with a single-atom copper tip with and without CO functionalization. The calculated images agree with state-of-the-art experiments, where the atomic structure of the tip apex is determined by AFM. The comparison further allows for detailed interpretation of the STM images.

First-principles investigations on structural, elastic, electronic properties and Debye temperature of orthorhombic Ni3Ta under pressure

NASA Astrophysics Data System (ADS)

Li, Pan; Zhang, Jianxin; Ma, Shiyu; Jin, Huixin; Zhang, Youjian; Zhang, Wenyang

2018-06-01

The structural, elastic, electronic properties and Debye temperature of Ni3Ta under different pressures are investigated using the first-principles method based on density functional theory. Our calculated equilibrium lattice parameters at 0 GPa well agree with the experimental and previous theoretical results. The calculated negative formation enthalpies and elastic constants both indicate that Ni3Ta is stable under different pressures. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν are calculated by the Voigt-Reuss-Hill method. The bigger ratio of B/G indicates Ni3Ta is ductile and the pressure can improve the ductility of Ni3Ta. In addition, the results of density of states and the charge density difference show that the stability of Ni3Ta is improved by the increasing pressure. The Debye temperature ΘD calculated from elastic modulus increases along with the pressure.

A Novel Application for the Cavalieri Principle: A Stereological and Methodological Study

PubMed Central

Altunkaynak, Berrin Zuhal; Altunkaynak, Eyup; Unal, Deniz; Unal, Bunyamin

2009-01-01

Objective The Cavalieri principle was applied to consecutive pathology sections that were photographed at the same magnification and used to estimate tissue volumes via superimposing a point counting grid on these images. The goal of this study was to perform the Cavalieri method quickly and practically. Materials and Methods In this study, 10 adult female Sprague Dawley rats were used. Brain tissue was removed and sampled both systematically and randomly. Brain volumes were estimated using two different methods. First, all brain slices were scanned with an HP ScanJet 3400C scanner, and their images were shown on a PC monitor. Brain volume was then calculated based on these images. Second, all brain slices were photographed in 10× magnification with a microscope camera, and brain volumes were estimated based on these micrographs. Results There was no statistically significant difference between the volume measurements of the two techniques (P>0.05; Paired Samples t Test). Conclusion This study demonstrates that personal computer scanning of serial tissue sections allows for easy and reliable volume determination based on the Cavalieri method. PMID:25610077

Novel optical gyroscope: proof of principle demonstration and future scope

PubMed Central

Srivastava, Shailesh; Rao D. S., Shreesha; Nandakumar, Hari

2016-01-01

We report the first proof-of-principle demonstration of the resonant optical gyroscope with reflector that we have recently proposed. The device is very different from traditional optical gyroscopes since it uses the inherent coupling between the clockwise and counterclockwise propagating waves to sense the rotation. Our demonstration confirms our theoretical analysis and simulations. We also demonstrate a novel method of biasing the gyroscope using orthogonal polarization states. The simplicity of the structure and the readout method, the theoretically predicted high sensitivities (better than 0.001 deg/hr), and the possibility of further performance enhancement using a related laser based active device, all have immense potential for attracting fresh research and technological initiatives. PMID:27694987

Concentration Waves in High-Entropy Alloys - a new alloy design approach

NASA Astrophysics Data System (ADS)

Singh, Prashant; Johnson, Duane D.

2015-03-01

Chemical short-range order (SRO) in solid solutions can be interpreted as a ``concentration wave'' - a Fourier decomposition of nascent order - identified experimentally via Warren-Cowley SRO parameters. We present a rigorous thermodynamic theory to predict and uniquely interpret the SRO in N -component alloys. Based on KKR-CPA electronic structure, we implemented this method using thermodynamic linear-response to include all alloying effects, e.g., band-filling, hybridization, Fermi -surface nesting and van Hove instabilities. We apply this first-principles method to high-entropy alloys (HEAs), i.e., solid solutions with N >4 that inhibit small-cell order due to large entropy competing against ordering enthalpy, as their properties are sensitive to SRO. We validated theory with comparison to experiments in A2 Nb-Al-Ti and A1 Cu-Ni-Zn . We then predict and analyze SRO and mechanical trends in Ni-Ti-Zr-Cu-Al and Co-Cr-Fe-Mn-Ni systems - showcasing this new first-principles-based alloy design method. Work was supported by the USDoE, Office of Sci., Basic Energy Sci., Materials Sci. and Eng. Division for `Materials Discovery.' Research was performed at Ames Lab, operated by Iowa State University under Contract #DE-AC02-07CH11358.

Structural and electronic phase transitions of ThS 2 from first-principles calculations

DOE PAGES

Guo, Yongliang; Wang, Changying; Qiu, Wujie; ...

2016-10-07

Performed a systematic study using first-principles methods of the pressure-induced structural and electronic phase transitions in ThS 2, which may play an important role in the next generation nuclear energy fuel technology.

Rapid and Automated Analytical Methods for Redox Species Based on Potentiometric Flow Injection Analysis Using Potential Buffers

PubMed Central

Ohura, Hiroki; Imato, Toshihiko

2011-01-01

Two analytical methods, which prove the utility of a potentiometric flow injection technique for determining various redox species, based on the use of some redox potential buffers, are reviewed. The first is a potentiometric flow injection method in which a redox couple such as Fe(III)-Fe(II), Fe(CN)6 3−-Fe(CN)(CN)6 4−, and bromide-bromine and a redox electrode or a combined platinum-bromide ion selective electrode are used. The analytical principle and advantages of the method are discussed, and several examples of its application are reported. Another example is a highly sensitive potentiometric flow injection method, in which a large transient potential change due to bromine or chlorine as an intermediate, generated during the reaction of the oxidative species with an Fe(III)-Fe(II) potential buffer containing bromide or chloride, is utilized. The analytical principle and details of the proposed method are described, and examples of several applications are described. The determination of trace amounts of hydrazine, based on the detection of a transient change in potential caused by the reaction with a Ce(IV)-Ce(III) potential buffer, is also described. PMID:21584280

Alchemical Free Energy Calculations for Nucleotide Mutations in Protein-DNA Complexes.

PubMed

Gapsys, Vytautas; de Groot, Bert L

2017-12-12

Nucleotide-sequence-dependent interactions between proteins and DNA are responsible for a wide range of gene regulatory functions. Accurate and generalizable methods to evaluate the strength of protein-DNA binding have long been sought. While numerous computational approaches have been developed, most of them require fitting parameters to experimental data to a certain degree, e.g., machine learning algorithms or knowledge-based statistical potentials. Molecular-dynamics-based free energy calculations offer a robust, system-independent, first-principles-based method to calculate free energy differences upon nucleotide mutation. We present an automated procedure to set up alchemical MD-based calculations to evaluate free energy changes occurring as the result of a nucleotide mutation in DNA. We used these methods to perform a large-scale mutation scan comprising 397 nucleotide mutation cases in 16 protein-DNA complexes. The obtained prediction accuracy reaches 5.6 kJ/mol average unsigned deviation from experiment with a correlation coefficient of 0.57 with respect to the experimentally measured free energies. Overall, the first-principles-based approach performed on par with the molecular modeling approaches Rosetta and FoldX. Subsequently, we utilized the MD-based free energy calculations to construct protein-DNA binding profiles for the zinc finger protein Zif268. The calculation results compare remarkably well with the experimentally determined binding profiles. The software automating the structure and topology setup for alchemical calculations is a part of the pmx package; the utilities have also been made available online at http://pmx.mpibpc.mpg.de/dna_webserver.html .

W17_geonuc “Application of the Spectral Element Method to improvement of Ground-based Nuclear Explosion Monitoring”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larmat, Carene; Rougier, Esteban; Lei, Zhou

This project is in support of the Source Physics Experiment SPE (Snelson et al. 2013), which aims to develop new seismic source models of explosions. One priority of this program is first principle numerical modeling to validate and extend current empirical models.

Murrinh Nganki (Our Language), 1.

ERIC Educational Resources Information Center

Street, Chester; And Others

This primer is the first in a series of four trial primers intended to teach the speakers of the Murrinh-patha language to read and write in their mother tongue. The approach and method of this primer is eclectic, based on principles developed by Dr. Sarah Gudschinsky. It has been designed to teach the vowels…

Predicting commuter flows in spatial networks using a radiation model based on temporal ranges

NASA Astrophysics Data System (ADS)

Ren, Yihui; Ercsey-Ravasz, Mária; Wang, Pu; González, Marta C.; Toroczkai, Zoltán

2014-11-01

Understanding network flows such as commuter traffic in large transportation networks is an ongoing challenge due to the complex nature of the transportation infrastructure and human mobility. Here we show a first-principles based method for traffic prediction using a cost-based generalization of the radiation model for human mobility, coupled with a cost-minimizing algorithm for efficient distribution of the mobility fluxes through the network. Using US census and highway traffic data, we show that traffic can efficiently and accurately be computed from a range-limited, network betweenness type calculation. The model based on travel time costs captures the log-normal distribution of the traffic and attains a high Pearson correlation coefficient (0.75) when compared with real traffic. Because of its principled nature, this method can inform many applications related to human mobility driven flows in spatial networks, ranging from transportation, through urban planning to mitigation of the effects of catastrophic events.

First-Principles Study on the Ferromagnetism and Curie Temperature of Mn-Doped AlX and InX (X=N, P, As, and Sb)

NASA Astrophysics Data System (ADS)

Sato, Kazunori; Dederichs, Peter H.; Katayama-Yoshida, Hiroshi

2007-02-01

We investigate the electronic structure and magnetic properties of AlN-, AlP-, AlAs-, AlSb-, InN-, InP-, InAs-, and InSb-based dilute magnetic semiconductors (DMS) with Mn impurities from first-principles. The electronic structure of DMS is calculated by using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method in connection with the local density approximation (LDA) and the LDA+U method. Describing the magnetic properties by a classical Heisenberg model, effective exchange interactions are calculated by applying magnetic force theorem for two impurities embedded in the CPA medium. With the calculated exchange interactions, TC is estimated by using the mean field approximation, the random phase approximation and the Monte Carlo simulation. It is found that the p-d exchange model [Dietl et al.: Science 287 (2000) 1019] is adequate for a limited class of DMS and insufficient to describe the ferromagnetism in wide gap semiconductor based DMS such as (Ga,Mn)N and the presently investigated (Al,Mn)N and (In,Mn)N.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ruikang; Hu, Run, E-mail: hurun@hust.edu.cn, E-mail: luoxb@hust.edu.cn; Luo, Xiaobing, E-mail: hurun@hust.edu.cn, E-mail: luoxb@hust.edu.cn

In this study, we developed a first-principle-based full-dispersion Monte Carlo simulation method to study the anisotropic phonon transport in wurtzite GaN thin film. The input data of thermal properties in MC simulations were calculated based on the first-principle method. The anisotropy of thermal conductivity in bulk wurtzite GaN is found to be strengthened by isotopic scatterings and reduced temperature, and the anisotropy reaches 40.08% for natural bulk GaN at 100 K. With the GaN thin film thickness decreasing, the anisotropy of the out-of-plane thermal conductivity is heavily reduced due to both the ballistic transport and the less importance of the low-frequencymore » phonons with anisotropic group velocities. On the contrary, it is observed that the in-plane thermal conductivity anisotropy of the GaN thin film is strengthened by reducing the film thickness. And the anisotropy reaches 35.63% when the natural GaN thin film thickness reduces to 50 nm at 300 K with the degree of specularity being zero. The anisotropy is also improved by increasing the surface roughness of the GaN thin film.« less

Role of zero-point effects in stabilizing the ground state structure of bulk Fe2P

NASA Astrophysics Data System (ADS)

Bhat, Soumya S.; Gupta, Kapil; Bhattacharjee, Satadeep; Lee, Seung-Cheol

2018-05-01

Structural stability of Fe2P is investigated in detail using first-principles calculations based on density functional theory. While the orthorhombic C23 phase is found to be energetically more stable, the experiments suggest it to be hexagonal C22 phase. In the present study, we show that in order to obtain the correct ground state structure of Fe2P from the first-principles based methods it is utmost necessary to consider the zero-point effects such as zero-point vibrations and spin fluctuations. This study demonstrates an exceptional case where a bulk material is stabilized by quantum effects, which are usually important in low-dimensional materials. Our results also indicate the possibility of magnetic field induced structural quantum phase transition in Fe2P, which should form the basis for further theoretical and experimental efforts.

First-principles-based kinetic Monte Carlo studies of diffusion of hydrogen in Ni–Al and Ni–Fe binary alloys

DOE PAGES

Tafen, De Nyago

2015-02-14

The diffusion of dilute hydrogen in fcc Ni–Al and Ni–Fe binary alloys was examined using kinetic Monte Carlo method with input kinetic parameters obtained from first-principles density functional theory. The simulation involves the implementation of computationally efficient energy barrier model that describes the configuration dependence of the hydrogen hopping. The predicted hydrogen diffusion coefficients in Ni and Ni 89.4Fe 10.6 are compared well with the available experimental data. In Ni–Al, the model predicts lower hydrogen diffusivity compared to that in Ni. Overall, diffusion prefactors and the effective activation energies of H in Ni–Fe and Ni–Al are concentration dependent of themore » alloying element. Furthermore, the changes in their values are the results of the short-range order (nearest-neighbor) effect on the interstitial diffusion of hydrogen in fcc Ni-based alloys.« less

Proposed correlation of modern processing principles for Ayurvedic herbal drug manufacturing: A systematic review.

PubMed

Jain, Rahi; Venkatasubramanian, Padma

2014-01-01

Quality Ayurvedic herbal medicines are potential, low-cost solutions for addressing contemporary healthcare needs of both Indian and global community. Correlating Ayurvedic herbal preparations with modern processing principles (MPPs) can help develop new and use appropriate technology for scaling up production of the medicines, which is necessary to meet the growing demand. Understanding the fundamental Ayurvedic principles behind formulation and processing is also important for improving the dosage forms. Even though Ayurvedic industry has adopted technologies from food, chemical and pharmaceutical industries, there is no systematic study to correlate the traditional and modern processing methods. This study is an attempt to provide a possible correlation between the Ayurvedic processing methods and MPPs. A systematic literature review was performed to identify the Ayurvedic processing methods by collecting information from English editions of classical Ayurveda texts on medicine preparation methods. Correlation between traditional and MPPs was done based on the techniques used in Ayurvedic drug processing. It was observed that in Ayurvedic medicine preparations there were two major types of processes, namely extraction, and separation. Extraction uses membrane rupturing and solute diffusion principles, while separation uses volatility, adsorption, and size-exclusion principles. The study provides systematic documentation of methods used in Ayurveda for herbal drug preparation along with its interpretation in terms of MPPs. This is the first step which can enable improving or replacing traditional techniques. New technologies or use of existing technologies can be used to improve the dosage forms and scaling up while maintaining the Ayurvedic principles similar to traditional techniques.

432- μm laser's beam-waist measurement for the polarimeter/interferometer on the EAST tokamak

NASA Astrophysics Data System (ADS)

Wang, Z. X.; Liu, H. Q.; Jie, Y. X.; Wu, M. Q.; Lan, T.; Zhu, X.; Zou, Z. Y.; Yang, Y.; Wei, X. C.; Zeng, L.; Li, G. S.; Gao, X.

2014-10-01

A far-infrared (FIR) polarimeter/interferometer (PI) system is under development for measurements of the current-density and the electron-density profiles in the EAST tokamak. The system will utilize three identical 432- μm CHCOOH lasers pumped by a CO2 laser. Measurements of the laser beam's waist size and position are basic works. This paper will introduce three methods with a beam profiler and several focusing optical elements. The beam profiler can be used to show the spatial energy distribution of the laser beam. The active area of the profiler is 12.4 × 12.4 mm2. Some focusing optical elements are needed to focus the beam in order for the beam profiler to receive the entire laser beam. Two principles and three methods are used in the measurement. The first and the third methods are based on the same principle, and the second method adopts an other principle. Due to the fast and convenient measurement, although the first method is a special form of the third and it can only give the size of beam waist, it is essential to the development of the experiment and it can provide guidance for the choices of the sizes of the optical elements in the next step. A concave mirror, a high-density polyethylene (HDPE) lens and a polymethylpentene (TPX) lens are each used in the measurement process. The results of these methods are close enough for the design of PI system's optical path.

First-principles quantum transport method for disordered nanoelectronics: Disorder-averaged transmission, shot noise, and device-to-device variability

NASA Astrophysics Data System (ADS)

Yan, Jiawei; Wang, Shizhuo; Xia, Ke; Ke, Youqi

2017-03-01

Because disorders are inevitable in realistic nanodevices, the capability to quantitatively simulate the disorder effects on electron transport is indispensable for quantum transport theory. Here, we report a unified and effective first-principles quantum transport method for analyzing effects of chemical or substitutional disorder on transport properties of nanoelectronics, including averaged transmission coefficient, shot noise, and disorder-induced device-to-device variability. All our theoretical formulations and numerical implementations are worked out within the framework of the tight-binding linear muffin tin orbital method. In this method, we carry out the electronic structure calculation with the density functional theory, treat the nonequilibrium statistics by the nonequilbrium Green's function method, and include the effects of multiple impurity scattering with the generalized nonequilibrium vertex correction (NVC) method in coherent potential approximation (CPA). The generalized NVC equations are solved from first principles to obtain various disorder-averaged two-Green's-function correlators. This method provides a unified way to obtain different disorder-averaged transport properties of disordered nanoelectronics from first principles. To test our implementation, we apply the method to investigate the shot noise in the disordered copper conductor, and find all our results for different disorder concentrations approach a universal Fano factor 1 /3 . As the second test, we calculate the device-to-device variability in the spin-dependent transport through the disordered Cu/Co interface and find the conductance fluctuation is very large in the minority spin channel and negligible in the majority spin channel. Our results agree well with experimental measurements and other theories. In both applications, we show the generalized nonequilibrium vertex corrections play a determinant role in electron transport simulation. Our results demonstrate the effectiveness of the first-principles generalized CPA-NVC for atomistic analysis of disordered nanoelectronics, extending the capability of quantum transport simulation.

Adsorption of organic molecules on mineral surfaces studied by first-principle calculations: A review.

PubMed

Zhao, Hongxia; Yang, Yong; Shu, Xin; Wang, Yanwei; Ran, Qianping

2018-04-09

First-principle calculations, especially by the density functional theory (DFT) methods, are becoming a power technique to study molecular structure and properties of organic/inorganic interfaces. This review introduces some recent examples on the study of adsorption models of organic molecules or oligomers on mineral surfaces and interfacial properties obtained from first-principles calculations. The aim of this contribution is to inspire scientists to benefit from first-principle calculations and to apply the similar strategies when studying and tailoring interfacial properties at the atomistic scale, especially for those interested in the design and development of new molecules and new products. Copyright © 2017. Published by Elsevier B.V.

Spatiotemporal coding in the cortex: information flow-based learning in spiking neural networks.

PubMed

Deco, G; Schürmann, B

1999-05-15

We introduce a learning paradigm for networks of integrate-and-fire spiking neurons that is based on an information-theoretic criterion. This criterion can be viewed as a first principle that demonstrates the experimentally observed fact that cortical neurons display synchronous firing for some stimuli and not for others. The principle can be regarded as the postulation of a nonparametric reconstruction method as optimization criteria for learning the required functional connectivity that justifies and explains synchronous firing for binding of features as a mechanism for spatiotemporal coding. This can be expressed in an information-theoretic way by maximizing the discrimination ability between different sensory inputs in minimal time.

Prediction of mass transfer coefficients in non-Newtonian fermentation media using first-principles methods.

PubMed

Radl, Stefan; Khinast, Johannes G

2007-08-01

Bubble flows in non-Newtonian fluids were analyzed using first-principles methods with the aim to compute and predict mass transfer coefficients in such fermentation media. The method we used is a Direct Numerical Simulation (DNS) of the reactive multiphase flow with deformable boundaries and interfaces. With this method, we are able for the first time to calculate mass transfer coefficients in non-Newtonian liquids of different rheologies without any experimental data. In the current article, shear-thinning fluids are considered. However, the results provide the basis for further investigations, such as the study of viscoelastic fluids. (c) 2007 Wiley Periodicals, Inc.

An Exemplar-Based Multi-View Domain Generalization Framework for Visual Recognition.

PubMed

Niu, Li; Li, Wen; Xu, Dong; Cai, Jianfei

2018-02-01

In this paper, we propose a new exemplar-based multi-view domain generalization (EMVDG) framework for visual recognition by learning robust classifier that are able to generalize well to arbitrary target domain based on the training samples with multiple types of features (i.e., multi-view features). In this framework, we aim to address two issues simultaneously. First, the distribution of training samples (i.e., the source domain) is often considerably different from that of testing samples (i.e., the target domain), so the performance of the classifiers learnt on the source domain may drop significantly on the target domain. Moreover, the testing data are often unseen during the training procedure. Second, when the training data are associated with multi-view features, the recognition performance can be further improved by exploiting the relation among multiple types of features. To address the first issue, considering that it has been shown that fusing multiple SVM classifiers can enhance the domain generalization ability, we build our EMVDG framework upon exemplar SVMs (ESVMs), in which a set of ESVM classifiers are learnt with each one trained based on one positive training sample and all the negative training samples. When the source domain contains multiple latent domains, the learnt ESVM classifiers are expected to be grouped into multiple clusters. To address the second issue, we propose two approaches under the EMVDG framework based on the consensus principle and the complementary principle, respectively. Specifically, we propose an EMVDG_CO method by adding a co-regularizer to enforce the cluster structures of ESVM classifiers on different views to be consistent based on the consensus principle. Inspired by multiple kernel learning, we also propose another EMVDG_MK method by fusing the ESVM classifiers from different views based on the complementary principle. In addition, we further extend our EMVDG framework to exemplar-based multi-view domain adaptation (EMVDA) framework when the unlabeled target domain data are available during the training procedure. The effectiveness of our EMVDG and EMVDA frameworks for visual recognition is clearly demonstrated by comprehensive experiments on three benchmark data sets.

Understanding integrated care: a comprehensive conceptual framework based on the integrative functions of primary care.

PubMed

Valentijn, Pim P; Schepman, Sanneke M; Opheij, Wilfrid; Bruijnzeels, Marc A

2013-01-01

Primary care has a central role in integrating care within a health system. However, conceptual ambiguity regarding integrated care hampers a systematic understanding. This paper proposes a conceptual framework that combines the concepts of primary care and integrated care, in order to understand the complexity of integrated care. The search method involved a combination of electronic database searches, hand searches of reference lists (snowball method) and contacting researchers in the field. The process of synthesizing the literature was iterative, to relate the concepts of primary care and integrated care. First, we identified the general principles of primary care and integrated care. Second, we connected the dimensions of integrated care and the principles of primary care. Finally, to improve content validity we held several meetings with researchers in the field to develop and refine our conceptual framework. The conceptual framework combines the functions of primary care with the dimensions of integrated care. Person-focused and population-based care serve as guiding principles for achieving integration across the care continuum. Integration plays complementary roles on the micro (clinical integration), meso (professional and organisational integration) and macro (system integration) level. Functional and normative integration ensure connectivity between the levels. The presented conceptual framework is a first step to achieve a better understanding of the inter-relationships among the dimensions of integrated care from a primary care perspective.

First-principles calculations, experimental study, and thermodynamic modeling of the Al-Co-Cr system.

PubMed

Liu, Xuan L; Gheno, Thomas; Lindahl, Bonnie B; Lindwall, Greta; Gleeson, Brian; Liu, Zi-Kui

2015-01-01

The phase relations and thermodynamic properties of the condensed Al-Co-Cr ternary alloy system are investigated using first-principles calculations based on density functional theory (DFT) and phase-equilibria experiments that led to X-ray diffraction (XRD) and electron probe micro-analysis (EPMA) measurements. A thermodynamic description is developed by means of the calculations of phase diagrams (CALPHAD) method using experimental and computational data from the present work and the literature. Emphasis is placed on modeling the bcc-A2, B2, fcc-γ, and tetragonal-σ phases in the temperature range of 1173 to 1623 K. Liquid, bcc-A2 and fcc-γ phases are modeled using substitutional solution descriptions. First-principles special quasirandom structures (SQS) calculations predict a large bcc-A2 (disordered)/B2 (ordered) miscibility gap, in agreement with experiments. A partitioning model is then used for the A2/B2 phase to effectively describe the order-disorder transitions. The critically assessed thermodynamic description describes all phase equilibria data well. A2/B2 transitions are also shown to agree well with previous experimental findings.

First-Principles pH Theory

NASA Astrophysics Data System (ADS)

Kim, Yong-Hyun; Zhang, S. B.

2006-03-01

Despite being one of the most important macroscopic measures and a long history even before the quantum mechanics, the concept of pH has rarely been mentioned in microscopic theories, nor being incorporated computationally into first-principles theory of aqueous solutions. Here, we formulate a theory for the pH dependence of solution formation energy by introducing the proton chemical potential as the microscopic counterpart of pH in atomistic solution models. Within the theory, the general acid-base chemistry can be cast in a simple pictorial representation. We adopt density-functional molecular dynamics to demonstrate the usefulness of the method by studying a number of solution systems including water, small solute molecules such as NH3 and HCOOH, and more complex amino acids with several functional groups. For pure water, we calculated the auto- ionization constant to be 13.2 with a 95 % accuracy. For other solutes, the calculated dissociation constants, i.e., the so- called pKa, are also in reasonable agreement with experiments. Our first-principles pH theory can be readily applied to broad solution chemistry problems such as redox reactions.

Problem-Centered Supplemental Instruction in Biology: Influence on Content Recall, Content Understanding, and Problem Solving Ability

NASA Astrophysics Data System (ADS)

Gardner, Joel; Belland, Brian R.

2017-08-01

To address the need for effective, efficient ways to apply active learning in undergraduate biology courses, in this paper, we propose a problem-centered approach that utilizes supplemental web-based instructional materials based on principles of active learning. We compared two supplementary web-based modules using active learning strategies: the first used Merrill's First Principles of Instruction as a framework for organizing multiple active learning strategies; the second used a traditional web-based approach. Results indicated that (a) the First Principles group gained significantly from pretest to posttest at the Remember level ( t(40) = -1.432, p = 0.08, ES = 0.4) and at the Problem Solving level ( U = 142.5, N1 = 21, N2 = 21, p = .02, ES = 0.7) and (b) the Traditional group gained significantly from pretest to posttest at the Remember level ( t(36) = 1.762, p = 0.043, ES = 0.6). Those in the First Principles group were significantly more likely than the traditional group to be confident in their ability to solve problems in the future (χ2 (2, N = 40) = 3.585, p = 0.09).

Cyclic density functional theory: A route to the first principles simulation of bending in nanostructures

NASA Astrophysics Data System (ADS)

Banerjee, Amartya S.; Suryanarayana, Phanish

2016-11-01

We formulate and implement Cyclic Density Functional Theory (Cyclic DFT) - a self-consistent first principles simulation method for nanostructures with cyclic symmetries. Using arguments based on Group Representation Theory, we rigorously demonstrate that the Kohn-Sham eigenvalue problem for such systems can be reduced to a fundamental domain (or cyclic unit cell) augmented with cyclic-Bloch boundary conditions. Analogously, the equations of electrostatics appearing in Kohn-Sham theory can be reduced to the fundamental domain augmented with cyclic boundary conditions. By making use of this symmetry cell reduction, we show that the electronic ground-state energy and the Hellmann-Feynman forces on the atoms can be calculated using quantities defined over the fundamental domain. We develop a symmetry-adapted finite-difference discretization scheme to obtain a fully functional numerical realization of the proposed approach. We verify that our formulation and implementation of Cyclic DFT is both accurate and efficient through selected examples. The connection of cyclic symmetries with uniform bending deformations provides an elegant route to the ab-initio study of bending in nanostructures using Cyclic DFT. As a demonstration of this capability, we simulate the uniform bending of a silicene nanoribbon and obtain its energy-curvature relationship from first principles. A self-consistent ab-initio simulation of this nature is unprecedented and well outside the scope of any other systematic first principles method in existence. Our simulations reveal that the bending stiffness of the silicene nanoribbon is intermediate between that of graphene and molybdenum disulphide - a trend which can be ascribed to the variation in effective thickness of these materials. We describe several future avenues and applications of Cyclic DFT, including its extension to the study of non-uniform bending deformations and its possible use in the study of the nanoscale flexoelectric effect.

Research on conceptual/innovative design for the life cycle

NASA Technical Reports Server (NTRS)

Cagan, Jonathan; Agogino, Alice M.

1990-01-01

The goal of this research is developing and integrating qualitative and quantitative methods for life cycle design. The definition of the problem includes formal computer-based methods limited to final detailing stages of design; CAD data bases do not capture design intent or design history; and life cycle issues were ignored during early stages of design. Viewgraphs outline research in conceptual design; the SYMON (SYmbolic MONotonicity analyzer) algorithm; multistart vector quantization optimization algorithm; intelligent manufacturing: IDES - Influence Diagram Architecture; and 1st PRINCE (FIRST PRINciple Computational Evaluator).

Multigrid based First-Principles Molecular Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fattebert, Jean-Luc; Osei-Kuffuor, Daniel; Dunn, Ian

2017-06-01

MGmol ls a First-Principles Molecular Dynamics code. It relies on the Born-Oppenheimer approximation and models the electronic structure using Density Functional Theory, either LDA or PBE. Norm-conserving pseudopotentials are used to model atomic cores.

The risks and responsible roles for psychiatrists who interact with the media.

PubMed

Cooke, Brian K; Goddard, Emily R; Werner, Tonia L; Cooke, Erinn O; Griffith, Ezra E H

2014-01-01

Journalists often turn to psychiatrists for analysis of medical, social, political, and cultural events that involve human behavior and illness. Once journalists seek their expertise, psychiatrists often rush to be helpful, which can lead to ineffective performance and to statements that may run afoul of principles of professional ethics. In this article, we discuss the bases on which the professionalism of psychiatrists may be impugned when they commit errors in their media presentations. Found within the Principles of Medical Ethics with Special Annotations Especially Applicable to Psychiatry, the Goldwater Rule prohibits certain behaviors when psychiatrists share professional opinions with the public. We first discuss the Goldwater Rule, highlighting the events that led to its development and the professional response to its enactment. We then present a method to guide psychiatrists in their interaction with the media that will help them avoid violating ethics principles or the law. The method encourages knowledge of a framework of ethics principles that in turn guide the psychiatrist's behavior and thinking as he contemplates accepting invitations to interact with the media. The ethics-based roles include the Teacher, the Storyteller, the Celebrity Commentator, the Hollywood Consultant, the Clinician, and the Advertiser. © 2014 American Academy of Psychiatry and the Law.

Research on hotspot discovery in internet public opinions based on improved K-means.

PubMed

Wang, Gensheng

2013-01-01

How to discover hotspot in the Internet public opinions effectively is a hot research field for the researchers related which plays a key role for governments and corporations to find useful information from mass data in the Internet. An improved K-means algorithm for hotspot discovery in internet public opinions is presented based on the analysis of existing defects and calculation principle of original K-means algorithm. First, some new methods are designed to preprocess website texts, select and express the characteristics of website texts, and define the similarity between two website texts, respectively. Second, clustering principle and the method of initial classification centers selection are analyzed and improved in order to overcome the limitations of original K-means algorithm. Finally, the experimental results verify that the improved algorithm can improve the clustering stability and classification accuracy of hotspot discovery in internet public opinions when used in practice.

Research on Hotspot Discovery in Internet Public Opinions Based on Improved K-Means

PubMed Central

2013-01-01

How to discover hotspot in the Internet public opinions effectively is a hot research field for the researchers related which plays a key role for governments and corporations to find useful information from mass data in the Internet. An improved K-means algorithm for hotspot discovery in internet public opinions is presented based on the analysis of existing defects and calculation principle of original K-means algorithm. First, some new methods are designed to preprocess website texts, select and express the characteristics of website texts, and define the similarity between two website texts, respectively. Second, clustering principle and the method of initial classification centers selection are analyzed and improved in order to overcome the limitations of original K-means algorithm. Finally, the experimental results verify that the improved algorithm can improve the clustering stability and classification accuracy of hotspot discovery in internet public opinions when used in practice. PMID:24106496

Multi-agent cooperation pursuit based on an extension of AALAADIN organisational model

NASA Astrophysics Data System (ADS)

Souidi, Mohammed El Habib; Songhao, Piao; Guo, Li; Lin, Chang

2016-11-01

An approach of cooperative pursuit for multiple mobile targets based on multi-agents system is discussed. In this kind of problem the pursuit process is divided into two kinds of tasks. The first one (coalition problem) is designed to solve the problem of the pursuit team formation. To achieve this mission, we used an innovative method based on a dynamic organisation and reorganisation of the pursuers' groups. We introduce our coalition strategy extended from the organisational agent, group, role model by assigning an access mechanism to the groups inspired by fuzzy logic principles. The second task (motion problem) is the treatment of the pursuers' motion strategy. To manage this problem we applied the principles of the Markov decision process. Simulation results show the feasibility and validity of the given proposal.

Hierarchical modeling and inference in ecology: The analysis of data from populations, metapopulations and communities

USGS Publications Warehouse

Royle, J. Andrew; Dorazio, Robert M.

2008-01-01

A guide to data collection, modeling and inference strategies for biological survey data using Bayesian and classical statistical methods. This book describes a general and flexible framework for modeling and inference in ecological systems based on hierarchical models, with a strict focus on the use of probability models and parametric inference. Hierarchical models represent a paradigm shift in the application of statistics to ecological inference problems because they combine explicit models of ecological system structure or dynamics with models of how ecological systems are observed. The principles of hierarchical modeling are developed and applied to problems in population, metapopulation, community, and metacommunity systems. The book provides the first synthetic treatment of many recent methodological advances in ecological modeling and unifies disparate methods and procedures. The authors apply principles of hierarchical modeling to ecological problems, including * occurrence or occupancy models for estimating species distribution * abundance models based on many sampling protocols, including distance sampling * capture-recapture models with individual effects * spatial capture-recapture models based on camera trapping and related methods * population and metapopulation dynamic models * models of biodiversity, community structure and dynamics.

A novel application for the cavalieri principle: a stereological and methodological study.

PubMed

Altunkaynak, Berrin Zuhal; Altunkaynak, Eyup; Unal, Deniz; Unal, Bunyamin

2009-08-01

The Cavalieri principle was applied to consecutive pathology sections that were photographed at the same magnification and used to estimate tissue volumes via superimposing a point counting grid on these images. The goal of this study was to perform the Cavalieri method quickly and practically. In this study, 10 adult female Sprague Dawley rats were used. Brain tissue was removed and sampled both systematically and randomly. Brain volumes were estimated using two different methods. First, all brain slices were scanned with an HP ScanJet 3400C scanner, and their images were shown on a PC monitor. Brain volume was then calculated based on these images. Second, all brain slices were photographed in 10× magnification with a microscope camera, and brain volumes were estimated based on these micrographs. There was no statistically significant difference between the volume measurements of the two techniques (P>0.05; Paired Samples t Test). This study demonstrates that personal computer scanning of serial tissue sections allows for easy and reliable volume determination based on the Cavalieri method.

Solid Rocket Fuel Constitutive Theory and Polymer Cure

NASA Technical Reports Server (NTRS)

Ream, Robert

2006-01-01

Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

NASA Astrophysics Data System (ADS)

Lee, Nien-En; Zhou, Jin-Jian; Agapito, Luis A.; Bernardi, Marco

2018-03-01

Predicting charge transport in organic molecular crystals is notoriously challenging. Carrier mobility calculations in organic semiconductors are dominated by quantum chemistry methods based on charge hopping, which are laborious and only moderately accurate. We compute from first principles the electron-phonon scattering and the phonon-limited hole mobility of naphthalene crystal in the framework of ab initio band theory. Our calculations combine GW electronic bandstructures, ab initio electron-phonon scattering, and the Boltzmann transport equation. The calculated hole mobility is in very good agreement with experiment between 100 -300 K , and we can predict its temperature dependence with high accuracy. We show that scattering between intermolecular phonons and holes regulates the mobility, though intramolecular phonons possess the strongest coupling with holes. We revisit the common belief that only rigid molecular motions affect carrier dynamics in organic molecular crystals. Our paper provides a quantitative and rigorous framework to compute charge transport in organic crystals and is a first step toward reconciling band theory and carrier hopping computational methods.

On the Development of Multi-Step Inverse FEM with Shell Model

NASA Astrophysics Data System (ADS)

Huang, Y.; Du, R.

2005-08-01

The inverse or one-step finite element approach is increasingly used in the sheet metal stamping industry to predict strain distribution and the initial blank shape in the preliminary design stage. Based on the existing theory, there are two types of method: one is based on the principle of virtual work and the other is based on the principle of extreme work. Much research has been conducted to improve the accuracy of simulation results. For example, based on the virtual work principle, Batoz et al. developed a new method using triangular DKT shell elements. In this new method, the bending and unbending effects are considered. Based on the principle of extreme work, Majlessi and et al. proposed the multi-step inverse approach with membrane elements and applied it to an axis-symmetric part. Lee and et al. presented an axis-symmetric shell element model to solve the similar problem. In this paper, a new multi-step inverse method is introduced with no limitation on the workpiece shape. It is a shell element model based on the virtual work principle. The new method is validated by means of comparing to the commercial software system (PAMSTAMP®). The comparison results indicate that the accuracy is good.

Mapping DNA methylation by transverse current sequencing: Reduction of noise from neighboring nucleotides

NASA Astrophysics Data System (ADS)

Alvarez, Jose; Massey, Steven; Kalitsov, Alan; Velev, Julian

Nanopore sequencing via transverse current has emerged as a competitive candidate for mapping DNA methylation without needed bisulfite-treatment, fluorescent tag, or PCR amplification. By eliminating the error producing amplification step, long read lengths become feasible, which greatly simplifies the assembly process and reduces the time and the cost inherent in current technologies. However, due to the large error rates of nanopore sequencing, single base resolution has not been reached. A very important source of noise is the intrinsic structural noise in the electric signature of the nucleotide arising from the influence of neighboring nucleotides. In this work we perform calculations of the tunneling current through DNA molecules in nanopores using the non-equilibrium electron transport method within an effective multi-orbital tight-binding model derived from first-principles calculations. We develop a base-calling algorithm accounting for the correlations of the current through neighboring bases, which in principle can reduce the error rate below any desired precision. Using this method we show that we can clearly distinguish DNA methylation and other base modifications based on the reading of the tunneling current.

Phase Stability for the Pd-Si System. First-Principles, Experiments, and Solution-Based Modeling

DOE PAGES

Zhou, S. H.; Huo, Y.; Napolitano, Ralph E.

2015-11-05

Relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd 5Si-μ, Pd 9Si 2-α, Pd 3 Si-β, Pd 2 Si-γ, and PdSi-δ are the stable phases at 0 K (-273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd 5 Si-μ, Pd 9 Si 2-α, Pd 3Si-β, and Pdmore » 2Si-γ are treated as stable phases down to 0 K (-273 °C), while the PdSi-δ is treated as being stable over a limited range, exhibiting a lower bound. Using these findings, a comprehensive solution-based thermodynamic model is formulated for the Pd-Si system, permitting phase diagram calculation. Moreover, the liquid phase is described using a three-species association model and other phases are treated as solid solutions, where a random substitutional model is adopted for Pd-fcc and Si-dia, and a two-sublattice model is employed for Pd 5Si-μ, Pd 9Si 2-α, Pd 3Si-β, Pd 2Si-γ, and PdSi-δ. Model parameters are fitted using available experimental data and first-principles data, and the resulting phase diagram is reported over the full range of compositions.« less

Phase Stability for the Pd-Si System. First-Principles, Experiments, and Solution-Based Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, S. H.; Huo, Y.; Napolitano, Ralph E.

Relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd 5Si-μ, Pd 9Si 2-α, Pd 3 Si-β, Pd 2 Si-γ, and PdSi-δ are the stable phases at 0 K (-273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd 5 Si-μ, Pd 9 Si 2-α, Pd 3Si-β, and Pdmore » 2Si-γ are treated as stable phases down to 0 K (-273 °C), while the PdSi-δ is treated as being stable over a limited range, exhibiting a lower bound. Using these findings, a comprehensive solution-based thermodynamic model is formulated for the Pd-Si system, permitting phase diagram calculation. Moreover, the liquid phase is described using a three-species association model and other phases are treated as solid solutions, where a random substitutional model is adopted for Pd-fcc and Si-dia, and a two-sublattice model is employed for Pd 5Si-μ, Pd 9Si 2-α, Pd 3Si-β, Pd 2Si-γ, and PdSi-δ. Model parameters are fitted using available experimental data and first-principles data, and the resulting phase diagram is reported over the full range of compositions.« less

Overcoming statistical bias to estimate genetic mating systems in open populations: a comparison of Bateman's principles between the sexes in a sex-role-reversed pipefish.

PubMed

Mobley, Kenyon B; Jones, Adam G

2013-03-01

The genetic mating system is a key component of the sexual selection process, yet methods for the quantification of mating systems remain controversial. One approach involves metrics derived from Bateman's principles, which are based on variances in mating and reproductive success and the relationship between them. However, these measures are extremely difficult to measure for both sexes in open populations, because missing data can result in biased estimates. Here, we develop a novel approach for the estimation of mating system metrics based on Bateman's principles and apply it to a microsatellite-based parentage analysis of a natural population of the dusky pipefish, Syngnathus floridae. Our results show that both male and female dusky pipefish have significantly positive Bateman gradients. However, females exhibit larger values of the opportunity for sexual selection and the opportunity for selection compared to males. These differences translate into a maximum intensity of sexual selection (S'max) for females three times larger than that for males. Overall, this study identifies a critical source of bias that affects studies of mating systems in open populations, presents a novel method for overcoming this bias, and applies this method for the first time in a sex-role-reversed pipefish. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

The 5-Step Method: Principles and Practice

ERIC Educational Resources Information Center

Copello, Alex; Templeton, Lorna; Orford, Jim; Velleman, Richard

2010-01-01

This article includes a description of the 5-Step Method. First, the origins and theoretical basis of the method are briefly described. This is followed by a discussion of the general principles that guide the delivery of the method. Each step is then described in more detail, including the content and focus of each of the five steps that include:…

Effect of Intermetallic on Electromigration and Atomic Diffusion in Cu/SnAg3.0Cu0.5/Cu Joints: Experimental and First-Principles Study

NASA Astrophysics Data System (ADS)

Zhou, Wei; Liu, Lijuan; Li, Baoling; Wu, Ping

2009-06-01

Electromigration phenomena in a one-dimensional Cu/SnAg3.0Cu0.5/Cu joint were investigated with current stressing. The special effect of intermetallic compound (IMC) layers on the formation of serious electromigration damage induced by nonuniform current density distribution was discussed based on experimental results. Meanwhile, hillocks were observed both at the anode and near the cathode of the joint, and they were described as the result of diffusion of atoms and compressive stress released along grain boundaries to the relatively free surface. Moreover, the diffusion behavior of Cu at the cathode was analyzed with the electromigration equation, and the stability of Ag atoms in the solder during electromigration was evaluated with a first-principles method.

A unified electrostatic and cavitation model for first-principles molecular dynamics in solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherlis, D A; Fattebert, J; Gygi, F

2005-11-14

The electrostatic continuum solvent model developed by Fattebert and Gygi is combined with a first-principles formulation of the cavitation energy based on a natural quantum-mechanical definition for the surface of a solute. Despite its simplicity, the cavitation contribution calculated by this approach is found to be in remarkable agreement with that obtained by more complex algorithms relying on a large set of parameters. The model allows for very efficient Car-Parrinello simulations of finite or extended systems in solution, and demonstrates a level of accuracy as good as that of established quantum-chemistry continuum solvent methods. They apply this approach to themore » study of tetracyanoethylene dimers in dichloromethane, providing valuable structural and dynamical insights on the dimerization phenomenon.« less

Structural stability, elastic and thermodynamic properties of Au-Cu alloys from first-principles calculations

NASA Astrophysics Data System (ADS)

Kong, Ge-Xing; Ma, Xiao-Juan; Liu, Qi-Jun; Li, Yong; Liu, Zheng-Tang

2018-03-01

Using first-principles calculations method based on density functional theory (DFT) with the Perdew-Burke-Ernzerhof (PBE) implementation of the generalized gradient approximation (GGA), we investigate the structural, elastic and thermodynamic properties of gold-copper intermetallic compounds (Au-Cu ICs). The calculated lattice parameters are in excellent agreement with experimental data. The elastic constants show that all the investigated Au-Cu alloys are mechanically stable. Elastic properties, including the shear modulus, Young's modulus, Poisson's ratio and Pugh's indicator, of the intermetallic compounds are evaluated and discussed, with special attention to the remarkable anisotropy displayed by Au-Cu ICs. Thermodynamic and transport properties including the Debye temperature, thermal conductivity and melting point are predicted from the averaged sound velocity and elastic moduli, using semi-empirical formulas.

[Discrimination of Red Tide algae by fluorescence spectra and principle component analysis].

PubMed

Su, Rong-guo; Hu, Xu-peng; Zhang, Chuan-song; Wang, Xiu-lin

2007-07-01

Fluorescence discrimination technology for 11 species of the Red Tide algae at genus level was constructed by principle component analysis and non-negative least squares. Rayleigh and Raman scattering peaks of 3D fluorescence spectra were eliminated by Delaunay triangulation method. According to the results of Fisher linear discrimination, the first principle component score and the second component score of 3D fluorescence spectra were chosen as discriminant feature and the feature base was established. The 11 algae species were tested, and more than 85% samples were accurately determinated, especially for Prorocentrum donghaiense, Skeletonema costatum, Gymnodinium sp., which have frequently brought Red tide in the East China Sea. More than 95% samples were right discriminated. The results showed that the genus discriminant feature of 3D fluorescence spectra of Red Tide algae given by principle component analysis could work well.

Oxygen vacancy effects in HfO2-based resistive switching memory: First principle study

NASA Astrophysics Data System (ADS)

Dai, Yuehua; Pan, Zhiyong; Wang, Feifei; Li, Xiaofeng

2016-08-01

The work investigated the shape and orientation of oxygen vacancy clusters in HfO2-base resistive random access memory (ReRAM) by using the first-principle method based on the density functional theory. Firstly, the formation energy of different local Vo clusters was calculated in four established orientation systems. Then, the optimized orientation and charger conductor shape were identified by comparing the isosurface plots of partial charge density, formation energy, and the highest isosurface value of oxygen vacancy. The calculated results revealed that the [010] orientation was the optimal migration path of Vo, and the shape of system D4 was the best charge conductor in HfO2, which effectively influenced the SET voltage, formation voltage and the ON/OFF ratio of the device. Afterwards, the PDOS of Hf near Vo and total density of states of the system D4_010 were obtained, revealing the composition of charge conductor was oxygen vacancy instead of metal Hf. Furthermore, the migration barriers of the Vo hopping between neighboring unit cells were calculated along four different orientations. The motion was proved along [010] orientation. The optimal circulation path for Vo migration in the HfO2 super-cell was obtained.

Translating community-based participatory research principles into practice.

PubMed

Burke, Jessica G; Hess, Sally; Hoffmann, Kamden; Guizzetti, Lisa; Loy, Ellyn; Gielen, Andrea; Bailey, Maryanne; Walnoha, Adrienne; Barbee, Genevieve; Yonas, Michael

2013-01-01

Although academics are trained in research methods, few receive formal training in strategies for implementing equitable community engaged research. Academics and their community partners can benefit from such direction and assistance as they establish and maintain community-based participatory research (CBPR) partnerships. Research partners from the University of Pittsburgh, the Johns Hopkins Center for Injury Research and Policy, and the House of Ruth Maryland, one of the nation's leading domestic violence centers serving Baltimore and the surrounding areas, joined together to design, implement, and evaluate a series of activities to increase local CPBR capacity. This article provides an overview of process and findings from two CBPR workshops jointly held for academic and community members and explores specific suggestions from the workshop participants about how to put the CBPR principles into practice to promote community engaged research to address intimate partner violence (IPV). Twenty-four academic and community partners with experience addressing IPV participated in the two workshops. Facilitators led discussions based on the core CPBR principles. Participants were asked to interpret those principles, identify actions that could help to put the principles into practice, and discuss challenges related to CBPR approaches for IPV research. Observational notes and transcripts of the discussions and workshop evaluations are summarized. The CBPR principles were interpreted and revised through consensus into common language that reflected the group discussion of the core CBPR principles. Workshop participants provided a range of actions for putting the principles into practice and identified the need for sensitivity in relation to IPV research. A majority of participants felt that the workshop generated novel ideas about how they could use CPBR in their own work. Translating CBPR principles into common, action-oriented language is a useful first step when building a new academic-community research partnership.

Theoretical investigations on diamondoids (CnHm, n = 10-41): Nomenclature, structural stabilities, and gap distributions

NASA Astrophysics Data System (ADS)

Wang, Ya-Ting; Zhao, Yu-Jun; Liao, Ji-Hai; Yang, Xiao-Bao

2018-01-01

Combining the congruence check and the first-principles calculations, we have systematically investigated the structural stabilities and gap distributions of possible diamondoids (CnHm) with the carbon numbers (n) from 10 to 41. A simple method for the nomenclature is proposed, which can be used to distinguish and screen the candidates with high efficiency. Different from previous theoretical studies, the possible diamondoids can be enumerated according to our nomenclature, without any pre-determination from experiments. The structural stabilities and electronic properties have been studied by density functional based tight binding and first-principles methods, where a nearly linear correlation is found between the energy gaps obtained by these two methods. According to the formation energy of structures, we have determined the stable configurations as a function of chemical potential. The maximum and minimum energy gaps are found to be dominated by the shape of diamondoids for clusters with a given number of carbon atoms, while the gap decreases in general as the size increases due to the quantum confinement.

New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring.

PubMed

van Gastel, Mark; Stuijk, Sander; de Haan, Gerard

2016-12-07

Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO 2 ) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO 2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted by motion-induced variations. We introduce a new principle that allows accurate remote measurements even during significant subject motion. We demonstrate the main advantage of the principle, i.e. that the optimal signature remains the same even when the SNR of the PPG signal drops significantly due to motion or limited measurement area. The evaluation uses recordings with breath-holding events, which induce hypoxemia in healthy moving subjects. The events lead to clinically relevant SpO 2 levels in the range 80-100%. The new principle is shown to greatly outperform current remote ratio-of-ratios based methods. The mean-absolute SpO 2 -error (MAE) is about 2 percentage-points during head movements, where the benchmark method shows a MAE of 24 percentage-points. Consequently, we claim ours to be the first method to reliably measure SpO 2 remotely during significant subject motion.

An effective approach of lesion segmentation within the breast ultrasound image based on the cellular automata principle.

PubMed

Liu, Yan; Cheng, H D; Huang, Jianhua; Zhang, Yingtao; Tang, Xianglong

2012-10-01

In this paper, a novel lesion segmentation within breast ultrasound (BUS) image based on the cellular automata principle is proposed. Its energy transition function is formulated based on global image information difference and local image information difference using different energy transfer strategies. First, an energy decrease strategy is used for modeling the spatial relation information of pixels. For modeling global image information difference, a seed information comparison function is developed using an energy preserve strategy. Then, a texture information comparison function is proposed for considering local image difference in different regions, which is helpful for handling blurry boundaries. Moreover, two neighborhood systems (von Neumann and Moore neighborhood systems) are integrated as the evolution environment, and a similarity-based criterion is used for suppressing noise and reducing computation complexity. The proposed method was applied to 205 clinical BUS images for studying its characteristic and functionality, and several overlapping area error metrics and statistical evaluation methods are utilized for evaluating its performance. The experimental results demonstrate that the proposed method can handle BUS images with blurry boundaries and low contrast well and can segment breast lesions accurately and effectively.

Infrared and visible image fusion scheme based on NSCT and low-level visual features

NASA Astrophysics Data System (ADS)

Li, Huafeng; Qiu, Hongmei; Yu, Zhengtao; Zhang, Yafei

2016-05-01

Multi-scale transform (MST) is an efficient tool for image fusion. Recently, many fusion methods have been developed based on different MSTs, and they have shown potential application in many fields. In this paper, we propose an effective infrared and visible image fusion scheme in nonsubsampled contourlet transform (NSCT) domain, in which the NSCT is firstly employed to decompose each of the source images into a series of high frequency subbands and one low frequency subband. To improve the fusion performance we designed two new activity measures for fusion of the lowpass subbands and the highpass subbands. These measures are developed based on the fact that the human visual system (HVS) percept the image quality mainly according to its some low-level features. Then, the selection principles of different subbands are presented based on the corresponding activity measures. Finally, the merged subbands are constructed according to the selection principles, and the final fused image is produced by applying the inverse NSCT on these merged subbands. Experimental results demonstrate the effectiveness and superiority of the proposed method over the state-of-the-art fusion methods in terms of both visual effect and objective evaluation results.

First-principles study on the thermal expansion of Ni-X binary alloys based on the quasi-harmonic Debye model

NASA Astrophysics Data System (ADS)

Shin, Yongjin; Jung, Woo-Sang; Lee, Young-Su

2016-11-01

In this study, we use the quasi-harmonic Debye model to predict the coefficient of thermal expansion of Ni- X binary alloys. The method bridges between the macroscopic elastic behavior and thermodynamic properties of materials without an expensive calculation of the volume dependence of the phonon density of states. Furthermore, the Grüneisen parameter is derived from the volume dependence of the Debye temperature, which is calculated from the first-principles elastic stiffness constants. The experimental coefficient of thermal expansion (CTE) of pure nickel is well reproduced, especially in the low temperature region. Among the few alloying elements tested, Al is predicted to slightly decrease the CTE whereas Mo and W are more effective in reducing the CTE. For the cases of Ni-X binary alloy systems, where the variation in the CTE is relatively small, the method used here appears to perform better than certain other formulations that rely entirely on the energy vs. volume relationship.

What is an adequate sample size? Operationalising data saturation for theory-based interview studies.

PubMed

Francis, Jill J; Johnston, Marie; Robertson, Clare; Glidewell, Liz; Entwistle, Vikki; Eccles, Martin P; Grimshaw, Jeremy M

2010-12-01

In interview studies, sample size is often justified by interviewing participants until reaching 'data saturation'. However, there is no agreed method of establishing this. We propose principles for deciding saturation in theory-based interview studies (where conceptual categories are pre-established by existing theory). First, specify a minimum sample size for initial analysis (initial analysis sample). Second, specify how many more interviews will be conducted without new ideas emerging (stopping criterion). We demonstrate these principles in two studies, based on the theory of planned behaviour, designed to identify three belief categories (Behavioural, Normative and Control), using an initial analysis sample of 10 and stopping criterion of 3. Study 1 (retrospective analysis of existing data) identified 84 shared beliefs of 14 general medical practitioners about managing patients with sore throat without prescribing antibiotics. The criterion for saturation was achieved for Normative beliefs but not for other beliefs or studywise saturation. In Study 2 (prospective analysis), 17 relatives of people with Paget's disease of the bone reported 44 shared beliefs about taking genetic testing. Studywise data saturation was achieved at interview 17. We propose specification of these principles for reporting data saturation in theory-based interview studies. The principles may be adaptable for other types of studies.

[Hospital-based psychological first aid provided to patients injured in the Lushan earthquake].

PubMed

Yin, Min; Li, Xiao-Lin; Li, Jing; Huang, Xue-Hua; Tao, Qing-Lan; Luo, Xi

2015-04-01

In the aftermath of the 7.0 earthquake that struck Lushan in China's Sichuan Province on April 20, 2013, a psychological crisis intervention working group was established in a hospital that was treating earthquake victims. Patients at this hospital received psychological first aid that was delivered in accordance with scientific, systematic, and standardized principles. This first aid employed a "rooting mode" methodology and was designed as a supportive psychological intervention. Mental assessment results showed that the general mental health, acute stress reactions, and anxiety and depression status of all of the 131 injured who received the psychological intervention had significantly improved (p < .05) during the two-week intervention period. This paper introduces the basic principles used to develop and provide this first aid, the approach used to organize the working groups, the main contents of the intervention, specific methods used, and intervention outcomes. This information is provided as a reference for providing localized psychological assistance in the aftermath of a disaster incident.

Patch-based models and algorithms for image processing: a review of the basic principles and methods, and their application in computed tomography.

PubMed

Karimi, Davood; Ward, Rabab K

2016-10-01

Image models are central to all image processing tasks. The great advancements in digital image processing would not have been made possible without powerful models which, themselves, have evolved over time. In the past decade, "patch-based" models have emerged as one of the most effective models for natural images. Patch-based methods have outperformed other competing methods in many image processing tasks. These developments have come at a time when greater availability of powerful computational resources and growing concerns over the health risks of the ionizing radiation encourage research on image processing algorithms for computed tomography (CT). The goal of this paper is to explain the principles of patch-based methods and to review some of their recent applications in CT. We first review the central concepts in patch-based image processing and explain some of the state-of-the-art algorithms, with a focus on aspects that are more relevant to CT. Then, we review some of the recent application of patch-based methods in CT. Patch-based methods have already transformed the field of image processing, leading to state-of-the-art results in many applications. More recently, several studies have proposed patch-based algorithms for various image processing tasks in CT, from denoising and restoration to iterative reconstruction. Although these studies have reported good results, the true potential of patch-based methods for CT has not been yet appreciated. Patch-based methods can play a central role in image reconstruction and processing for CT. They have the potential to lead to substantial improvements in the current state of the art.

Hierarchical Coupling of First-Principles Molecular Dynamics with Advanced Sampling Methods.

PubMed

Sevgen, Emre; Giberti, Federico; Sidky, Hythem; Whitmer, Jonathan K; Galli, Giulia; Gygi, Francois; de Pablo, Juan J

2018-05-14

We present a seamless coupling of a suite of codes designed to perform advanced sampling simulations, with a first-principles molecular dynamics (MD) engine. As an illustrative example, we discuss results for the free energy and potential surfaces of the alanine dipeptide obtained using both local and hybrid density functionals (DFT), and we compare them with those of a widely used classical force field, Amber99sb. In our calculations, the efficiency of first-principles MD using hybrid functionals is augmented by hierarchical sampling, where hybrid free energy calculations are initiated using estimates obtained with local functionals. We find that the free energy surfaces obtained from classical and first-principles calculations differ. Compared to DFT results, the classical force field overestimates the internal energy contribution of high free energy states, and it underestimates the entropic contribution along the entire free energy profile. Using the string method, we illustrate how these differences lead to different transition pathways connecting the metastable minima of the alanine dipeptide. In larger peptides, those differences would lead to qualitatively different results for the equilibrium structure and conformation of these molecules.

A judging principle of crucial vibrational transmission paths in plates

NASA Astrophysics Data System (ADS)

Wang, Bin; Li, Dong-Xu; Jiang, Jian-Ping; Liao, Yi-Huan

2016-10-01

This paper developed a judging principle of crucial vibrational transmission path (VTP) in plates. Novel generalized definitions of VTPs are given referred to the meaning of streamlines. And by comparing governing equations, the similarity between energy flow and fluid motion is firstly found so that an analytic method of VTPs in plates is proposed by analogy with fluid motion. Hereafter, the crucial VTP is defined for energy flows at objective points and relative judging criteria is given. Finally, based on two numerical experiments of passive control, the judging principle is indirectly verified by comparing the reduction effects of energy flows at focused points and relative judgment results of crucial VTPs. This paper is meaningful for analyzing and applying the VTPs in plates to guide the control design in future.

The Logic of Sense Incorporated to the Notion of Inquiry as an Orientation for Learning: Two Classroom Experiences

ERIC Educational Resources Information Center

Vásquez, Gonzalo Camacho

2017-01-01

A reflection about two classroom experiences is presented in the attempt to incorporate the Logic of Sense into the notion of inquiry for learning. The author used the method of Experimentation introduced by Deleuze and Guattari, who based its principles on philosophical conceptions by Baruch Spinoza. The first experience is conducted with…

Comparing Outcomes between a Traditional F2F Course and a Blended ITV Course

ERIC Educational Resources Information Center

Gerlich, R. Nicholas; Sollosy, Marc

2011-01-01

Two sections of the Principles of Management course were examined to compare student outcomes based on course delivery method. The first section was a traditional F2F class, while the second section was parallel cohorts of students meeting in two separate locations, but linked by ITV (Interactive Television). The professor appeared once per week…

First principles statistical mechanics of alloys and magnetism

NASA Astrophysics Data System (ADS)

Eisenbach, Markus; Khan, Suffian N.; Li, Ying Wai

Modern high performance computing resources are enabling the exploration of the statistical physics of phase spaces with increasing size and higher fidelity of the Hamiltonian of the systems. For selected systems, this now allows the combination of Density Functional based first principles calculations with classical Monte Carlo methods for parameter free, predictive thermodynamics of materials. We combine our locally selfconsistent real space multiple scattering method for solving the Kohn-Sham equation with Wang-Landau Monte-Carlo calculations (WL-LSMS). In the past we have applied this method to the calculation of Curie temperatures in magnetic materials. Here we will present direct calculations of the chemical order - disorder transitions in alloys. We present our calculated transition temperature for the chemical ordering in CuZn and the temperature dependence of the short-range order parameter and specific heat. Finally we will present the extension of the WL-LSMS method to magnetic alloys, thus allowing the investigation of the interplay of magnetism, structure and chemical order in ferrous alloys. This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division and it used Oak Ridge Leadership Computing Facility resources at Oak Ridge National Laboratory.

First-principles method for electron-phonon coupling and electron mobility: Applications to two-dimensional materials

NASA Astrophysics Data System (ADS)

Gunst, Tue; Markussen, Troels; Stokbro, Kurt; Brandbyge, Mads

2016-01-01

We present density functional theory calculations of the phonon-limited mobility in n -type monolayer graphene, silicene, and MoS2. The material properties, including the electron-phonon interaction, are calculated from first principles. We provide a detailed description of the normalized full-band relaxation time approximation for the linearized Boltzmann transport equation (BTE) that includes inelastic scattering processes. The bulk electron-phonon coupling is evaluated by a supercell method. The method employed is fully numerical and does therefore not require a semianalytic treatment of part of the problem and, importantly, it keeps the anisotropy information stored in the coupling as well as the band structure. In addition, we perform calculations of the low-field mobility and its dependence on carrier density and temperature to obtain a better understanding of transport in graphene, silicene, and monolayer MoS2. Unlike graphene, the carriers in silicene show strong interaction with the out-of-plane modes. We find that graphene has more than an order of magnitude higher mobility compared to silicene in the limit where the silicene out-of-plane interaction is reduced to zero (by substrate interaction, clamping, or similar). If the out-of-plane interaction is not actively reduced, the mobility of silicene will essentially be zero. For MoS2, we obtain several orders of magnitude lower mobilities compared to graphene in agreement with other recent theoretical results. The simulations illustrate the predictive capabilities of the newly implemented BTE solver applied in simulation tools based on first-principles and localized basis sets.

Elastic, dynamical, and electronic properties of LiHg and Li3Hg: First-principles study

NASA Astrophysics Data System (ADS)

Wang, Yan; Hao, Chun-Mei; Huang, Hong-Mei; Li, Yan-Ling

2018-04-01

The elastic, dynamical, and electronic properties of cubic LiHg and Li3Hg were investigated based on first-principles methods. The elastic constants and phonon spectral calculations confirmed the mechanical and dynamical stability of the materials at ambient conditions. The obtained elastic moduli of LiHg are slightly larger than those of Li3Hg. Both LiHg and Li3Hg are ductile materials with strong shear anisotropy as metals with mixed ionic, covalent, and metallic interactions. The calculated Debye temperatures are 223.5 K and 230.6 K for LiHg and Li3Hg, respectively. The calculated phonon frequency of the T2 g mode in Li3Hg is 326.8 cm-1. The p states from the Hg and Li atoms dominate the electronic structure near the Fermi level. These findings may inspire further experimental and theoretical study on the potential technical and engineering applications of similar alkali metal-based intermetallic compounds.

[Development of selective determination methods for quinones with fluorescence and chemiluminescence detection and their application to environmental and biological samples].

PubMed

Kishikawa, Naoya

2010-10-01

Quinones are compounds that have various characteristics such as a biological electron transporter, an industrial product and a harmful environmental pollutant. Therefore, an effective determination method for quinones is required in many fields. This review describes the development of sensitive and selective determination methods for quinones based on some detection principles and their application to analyses in environmental, pharmaceutical and biological samples. Firstly, a fluorescence method was developed based on fluorogenic derivatization of quinones and applied to environmental analysis. Secondly, a luminol chemiluminescence method was developed based on generation of reactive oxygen species through the redox cycle of quinone and applied to pharmaceutical analysis. Thirdly, a photo-induced chemiluminescence method was developed based on formation of reactive oxygen species and fluorophore or chemiluminescence enhancer by the photoreaction of quinones and applied to biological and environmental analyses.

First-principles calculations of the structural, elastic and thermodynamic properties of mackinawite (FeS) and pyrite (FeS2)

NASA Astrophysics Data System (ADS)

Wen, Xiangli; Liang, Yuxuan; Bai, Pengpeng; Luo, Bingwei; Fang, Teng; Yue, Luo; An, Teng; Song, Weiyu; Zheng, Shuqi

2017-11-01

The thermodynamic properties of Fe-S compounds with different crystal structure are very different. In this study, the structural, elastic and thermodynamic properties of mackinawite (FeS) and pyrite (FeS2) were investigated by first-principles calculations. Examination of the electronic density of states shows that mackinawite (FeS) is metallic and that pyrite (FeS2) is a semiconductor with a band gap of Eg = 1.02 eV. Using the stress-strain method, the elastic properties including the bulk modulus and shear modulus were derived from the elastic Cij data. Density functional perturbation theory (DFPT) calculations within the quasi-harmonic approximation (QHA) were used to calculate the thermodynamic properties, and the two Fe-S compounds are found to be dynamically stable. The isothermal bulk modulus, thermal expansion coefficient, heat capacities, Gibbs free energy and entropy of the Fe-S compounds are obtained by first-principles phonon calculations. Furthermore, the temperature of the mackinawite (FeS) ⟶ pyrite (FeS2) phase transition at 0 GPa was predicted. Based on the calculation results, the model for prediction of Fe-S compounds in the Fe-H2S-H2O system was improved.

Privacy Management and Networked PPD Systems - Challenges Solutions.

PubMed

Ruotsalainen, Pekka; Pharow, Peter; Petersen, Francoise

2015-01-01

Modern personal portable health devices (PPDs) become increasingly part of a larger, inhomogeneous information system. Information collected by sensors are stored and processed in global clouds. Services are often free of charge, but at the same time service providers' business model is based on the disclosure of users' intimate health information. Health data processed in PPD networks is not regulated by health care specific legislation. In PPD networks, there is no guarantee that stakeholders share same ethical principles with the user. Often service providers have own security and privacy policies and they rarely offer to the user possibilities to define own, or adapt existing privacy policies. This all raises huge ethical and privacy concerns. In this paper, the authors have analyzed privacy challenges in PPD networks from users' viewpoint using system modeling method and propose the principle "Personal Health Data under Personal Control" must generally be accepted at global level. Among possible implementation of this principle, the authors propose encryption, computer understandable privacy policies, and privacy labels or trust based privacy management methods. The latter can be realized using infrastructural trust calculation and monitoring service. A first step is to require the protection of personal health information and the principle proposed being internationally mandatory. This requires both regulatory and standardization activities, and the availability of open and certified software application which all service providers can implement. One of those applications should be the independent Trust verifier.

Physical–chemical determinants of coil conformations in globular proteins

PubMed Central

Perskie, Lauren L; Rose, George D

2010-01-01

We present a method with the potential to generate a library of coil segments from first principles. Proteins are built from α-helices and/or β-strands interconnected by these coil segments. Here, we investigate the conformational determinants of short coil segments, with particular emphasis on chain turns. Toward this goal, we extracted a comprehensive set of two-, three-, and four-residue turns from X-ray–elucidated proteins and classified them by conformation. A remarkably small number of unique conformers account for most of this experimentally determined set, whereas remaining members span a large number of rare conformers, many occurring only once in the entire protein database. Factors determining conformation were identified via Metropolis Monte Carlo simulations devised to test the effectiveness of various energy terms. Simulated structures were validated by comparison to experimental counterparts. After filtering rare conformers, we found that 98% of the remaining experimentally determined turn population could be reproduced by applying a hydrogen bond energy term to an exhaustively generated ensemble of clash-free conformers in which no backbone polar group lacks a hydrogen-bond partner. Further, at least 90% of longer coil segments, ranging from 5- to 20 residues, were found to be structural composites of these shorter primitives. These results are pertinent to protein structure prediction, where approaches can be divided into either empirical or ab initio methods. Empirical methods use database-derived information; ab initio methods rely on physical–chemical principles exclusively. Replacing the database-derived coil library with one generated from first principles would transform any empirically based method into its corresponding ab initio homologue. PMID:20512968

Diagnosis: Reasoning from first principles and experiential knowledge

NASA Technical Reports Server (NTRS)

Williams, Linda J. F.; Lawler, Dennis G.

1987-01-01

Completeness, efficiency and autonomy are requirements for suture diagnostic reasoning systems. Methods for automating diagnostic reasoning systems include diagnosis from first principles (i.e., reasoning from a thorough description of structure and behavior) and diagnosis from experiential knowledge (i.e., reasoning from a set of examples obtained from experts). However, implementation of either as a single reasoning method fails to meet these requirements. The approach of combining reasoning from first principles and reasoning from experiential knowledge does address the requirements discussed above and can possibly ease some of the difficulties associated with knowledge acquisition by allowing developers to systematically enumerate a portion of the knowledge necessary to build the diagnosis program. The ability to enumerate knowledge systematically facilitates defining the program's scope, completeness, and competence and assists in bounding, controlling, and guiding the knowledge acquisition process.

[Modeling and implementation method for the automatic biochemistry analyzer control system].

PubMed

Wang, Dong; Ge, Wan-cheng; Song, Chun-lin; Wang, Yun-guang

2009-03-01

In this paper the system structure The automatic biochemistry analyzer is a necessary instrument for clinical diagnostics. First of is analyzed. The system problems description and the fundamental principles for dispatch are brought forward. Then this text puts emphasis on the modeling for the automatic biochemistry analyzer control system. The objects model and the communications model are put forward. Finally, the implementation method is designed. It indicates that the system based on the model has good performance.

Experimental and first-principles study of photoluminescent and optical properties of Na-doped CuAlO2: the role of the NaAl-2Na i complex

NASA Astrophysics Data System (ADS)

Liu, Ruijian; Li, Yongfeng; Yao, Bin; Ding, Zhanhui; Deng, Rui; Zhang, Ligong; Zhao, Haifeng; Liu, Lei

2015-08-01

We report that a band-tail emission at 3.08 eV, lower than near-band-edge energy, is observed in photoluminescence measurements of bulk Na-doped CuAlO2. The band-tail emission is attributed to Na-related defects. Electronic structure calculations based on the first-principles method demonstrate that the donor-acceptor compensated complex of NaAl-2Na i in Na-doped CuAlO2 plays a key role in leading to the band-tail emission and bandgap narrowing. Furthermore, Hall effect measurements indicates that the hole concentration in CuAlO2 is independent on Na doping, which is well understood by the donor-acceptor compensation effect of NaAl-2Na i complex.

First-Principles Study of Charge Diffusion between Proximate Solid-State Qubits and Its Implications on Sensor Applications

NASA Astrophysics Data System (ADS)

Chou, Jyh-Pin; Bodrog, Zoltán; Gali, Adam

2018-03-01

Solid-state qubits from paramagnetic point defects in solids are promising platforms to realize quantum networks and novel nanoscale sensors. Recent advances in materials engineering make it possible to create proximate qubits in solids that might interact with each other, leading to electron spin or charge fluctuation. Here we develop a method to calculate the tunneling-mediated charge diffusion between point defects from first principles and apply it to nitrogen-vacancy (NV) qubits in diamond. The calculated tunneling rates are in quantitative agreement with previous experimental data. Our results suggest that proximate neutral and negatively charged NV defect pairs can form a NV-NV molecule. A tunneling-mediated model for the source of decoherence of the near-surface NV qubits is developed based on our findings on the interacting qubits in diamond.

Structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 phases from first-principles calculations

NASA Astrophysics Data System (ADS)

Li, X. D.; Li, K.; Wei, C. H.; Han, W. D.; Zhou, N. G.

2018-06-01

The structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 are systematically investigated by using first-principles calculations method based on density functional theory (DFT). The calculated formation enthalpies and cohesive energies show that CaSi2 possesses the greatest structural stability and CaSi has the strongest alloying ability. The structural stability of the three phases is compared according to electronic structures. Further analysis on electronic structures indicates that the bonding of these phases exhibits the combinations of metallic, covalent, and ionic bonds. The elastic constants are calculated, and the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and anisotropy factor of polycrystalline materials are deduced. Additionally, the thermodynamic properties were theoretically predicted and discussed.

A long-term target detection approach in infrared image sequence

NASA Astrophysics Data System (ADS)

Li, Hang; Zhang, Qi; Wang, Xin; Hu, Chao

2016-10-01

An automatic target detection method used in long term infrared (IR) image sequence from a moving platform is proposed. Firstly, based on POME(the principle of maximum entropy), target candidates are iteratively segmented. Then the real target is captured via two different selection approaches. At the beginning of image sequence, the genuine target with litter texture is discriminated from other candidates by using contrast-based confidence measure. On the other hand, when the target becomes larger, we apply online EM method to estimate and update the distributions of target's size and position based on the prior detection results, and then recognize the genuine one which satisfies both the constraints of size and position. Experimental results demonstrate that the presented method is accurate, robust and efficient.

First Principles Predictions of the Structure and Function of G-Protein-Coupled Receptors: Validation for Bovine Rhodopsin

PubMed Central

Trabanino, Rene J.; Hall, Spencer E.; Vaidehi, Nagarajan; Floriano, Wely B.; Kam, Victor W. T.; Goddard, William A.

2004-01-01

G-protein-coupled receptors (GPCRs) are involved in cell communication processes and with mediating such senses as vision, smell, taste, and pain. They constitute a prominent superfamily of drug targets, but an atomic-level structure is available for only one GPCR, bovine rhodopsin, making it difficult to use structure-based methods to design receptor-specific drugs. We have developed the MembStruk first principles computational method for predicting the three-dimensional structure of GPCRs. In this article we validate the MembStruk procedure by comparing its predictions with the high-resolution crystal structure of bovine rhodopsin. The crystal structure of bovine rhodopsin has the second extracellular (EC-II) loop closed over the transmembrane regions by making a disulfide linkage between Cys-110 and Cys-187, but we speculate that opening this loop may play a role in the activation process of the receptor through the cysteine linkage with helix 3. Consequently we predicted two structures for bovine rhodopsin from the primary sequence (with no input from the crystal structure)—one with the EC-II loop closed as in the crystal structure, and the other with the EC-II loop open. The MembStruk-predicted structure of bovine rhodopsin with the closed EC-II loop deviates from the crystal by 2.84 Å coordinate root mean-square (CRMS) in the transmembrane region main-chain atoms. The predicted three-dimensional structures for other GPCRs can be validated only by predicting binding sites and energies for various ligands. For such predictions we developed the HierDock first principles computational method. We validate HierDock by predicting the binding site of 11-cis-retinal in the crystal structure of bovine rhodopsin. Scanning the whole protein without using any prior knowledge of the binding site, we find that the best scoring conformation in rhodopsin is 1.1 Å CRMS from the crystal structure for the ligand atoms. This predicted conformation has the carbonyl O only 2.82 Å from the N of Lys-296. Making this Schiff base bond and minimizing leads to a final conformation only 0.62 Å CRMS from the crystal structure. We also used HierDock to predict the binding site of 11-cis-retinal in the MembStruk-predicted structure of bovine rhodopsin (closed loop). Scanning the whole protein structure leads to a structure in which the carbonyl O is only 2.85 Å from the N of Lys-296. Making this Schiff base bond and minimizing leads to a final conformation only 2.92 Å CRMS from the crystal structure. The good agreement of the ab initio-predicted protein structures and ligand binding site with experiment validates the use of the MembStruk and HierDock first principles' methods. Since these methods are generic and applicable to any GPCR, they should be useful in predicting the structures of other GPCRs and the binding site of ligands to these proteins. PMID:15041637

Free-energy analyses of a proton transfer reaction by simulated-tempering umbrella sampling and first-principles molecular dynamics simulations.

PubMed

Mori, Yoshiharu; Okamoto, Yuko

2013-02-01

A simulated tempering method, which is referred to as simulated-tempering umbrella sampling, for calculating the free energy of chemical reactions is proposed. First principles molecular dynamics simulations with this simulated tempering were performed to study the intramolecular proton transfer reaction of malonaldehyde in an aqueous solution. Conformational sampling in reaction coordinate space can be easily enhanced with this method, and the free energy along a reaction coordinate can be calculated accurately. Moreover, the simulated-tempering umbrella sampling provides trajectory data more efficiently than the conventional umbrella sampling method.

First-principles modeling of biological systems and structure-based drug-design.

PubMed

Sgrignani, Jacopo; Magistrato, Alessandra

2013-03-01

Molecular modeling techniques play a relevant role in drug design providing detailed information at atomistic level on the structural, dynamical, mechanistic and electronic properties of biological systems involved in diseases' onset, integrating and supporting commonly used experimental approaches. These information are often not accessible to the experimental techniques taken singularly, but are of crucial importance for drug design. Due to the enormous increase of the computer power in the last decades, quantum mechanical (QM) or first-principles-based methods have become often used to address biological issues of pharmaceutical relevance, providing relevant information for drug design. Due to their complexity and their size, biological systems are often investigated by means of a mixed quantum-classical (QM/MM) approach, which treats at an accurate QM level a limited chemically relevant portion of the system and at the molecular mechanics (MM) level the remaining of the biomolecule and its environment. This method provides a good compromise between computational cost and accuracy, allowing to characterize the properties of the biological system and the (free) energy landscape of the process in study with the accuracy of a QM description. In this review, after a brief introduction of QM and QM/MM methods, we will discuss few representative examples, taken from our work, of the application of these methods in the study of metallo-enzymes of pharmaceutical interest, of metal-containing anticancer drugs targeting the DNA as well as of neurodegenerative diseases. The information obtained from these studies may provide the basis for a rationale structure-based drug design of new and more efficient inhibitors or drugs.

An ergonomics based design research method for the arrangement of helicopter flight instrument panels.

PubMed

Alppay, Cem; Bayazit, Nigan

2015-11-01

In this paper, we study the arrangement of displays in flight instrument panels of multi-purpose civil helicopters following a user-centered design method based on ergonomics principles. Our methodology can also be described as a user-interface arrangement methodology based on user opinions and preferences. This study can be outlined as gathering user-centered data using two different research methods and then analyzing and integrating the collected data to come up with an optimal instrument panel design. An interview with helicopter pilots formed the first step of our research. In that interview, pilots were asked to provide a quantitative evaluation of basic interface arrangement principles. In the second phase of the research, a paper prototyping study was conducted with same pilots. The final phase of the study entailed synthesizing the findings from interviews and observational studies to formulate an optimal flight instrument arrangement methodology. The primary results that we present in our paper are the methodology that we developed and three new interface arrangement concepts, namely relationship of inseparability, integrated value and locational value. An optimum instrument panel arrangement is also proposed by the researchers. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Finding the Density of a Liquid Using a Metre Rule

ERIC Educational Resources Information Center

Chattopadhyay, K. N.

2008-01-01

A simple method, which is based on the principle of moment of forces only, is described for the determination of the density of liquids without measuring the mass and volume. At first, an empty test tube and a solid substance, which are hung on each side of a metre rule, are balanced and the moment arm of the test tube is measured. Keeping the…

Vertical electronic transport in van de waals heterostructures

NASA Astrophysics Data System (ADS)

Qiao, Zhenhua; Zhenhua Qiao's Group Team

In this work, we will introduce the theoretical investigation of the vertical electronic transport in various heterostructrues by using both tight-binding method and first-principles calculations. Counterintuitively, we find that the maximum electronic transport is achieved at very limited scattering regions but not at large overlapped catering regions. Based on this finding, we design a special setup to measure the tunneling effect in rotated bilayer systems.

Wavelength calibration of an imaging spectrometer based on Savart interferometer

NASA Astrophysics Data System (ADS)

Li, Qiwei; Zhang, Chunmin; Yan, Tingyu; Quan, Naicheng; Wei, Yutong; Tong, Cuncun

2017-09-01

The basic principle of Fourier-transform imaging spectrometer (FTIS) based on Savart interferometer is outlined. The un-identical distribution of the optical path difference which leads to the wavelength drift of each row of the interferogram is analyzed. Two typical methods for wavelength calibration of the presented system are described. The first method unifies different spectral intervals and maximum spectral frequencies of each row by a reference monochromatic light with known wavelength, and the dispersion compensation of Savart interferometer is also involved. The second approach is based on the least square fitting which builds the functional relation between recovered wavelength, row number and calibrated wavelength by concise equations. The effectiveness of the two methods is experimentally demonstrated with monochromatic lights and mixed light source across the detecting band of the system, and the results indicate that the first method has higher precision and the mean root-mean-square error of the recovered wavelengths is significantly reduced from 19.896 nm to 1.353 nm, while the second method is more convenient to implement and also has good precision of 2.709 nm.

Comparing the Principle-Based SBH Maieutic Method to Traditional Case Study Methods of Teaching Media Ethics

ERIC Educational Resources Information Center

Grant, Thomas A.

2012-01-01

This quasi-experimental study at a Northwest university compared two methods of teaching media ethics, a class taught with the principle-based SBH Maieutic Method (n = 25) and a class taught with a traditional case study method (n = 27), with a control group (n = 21) that received no ethics training. Following a 16-week intervention, a one-way…

Robust MST-Based Clustering Algorithm.

PubMed

Liu, Qidong; Zhang, Ruisheng; Zhao, Zhili; Wang, Zhenghai; Jiao, Mengyao; Wang, Guangjing

2018-06-01

Minimax similarity stresses the connectedness of points via mediating elements rather than favoring high mutual similarity. The grouping principle yields superior clustering results when mining arbitrarily-shaped clusters in data. However, it is not robust against noises and outliers in the data. There are two main problems with the grouping principle: first, a single object that is far away from all other objects defines a separate cluster, and second, two connected clusters would be regarded as two parts of one cluster. In order to solve such problems, we propose robust minimum spanning tree (MST)-based clustering algorithm in this letter. First, we separate the connected objects by applying a density-based coarsening phase, resulting in a low-rank matrix in which the element denotes the supernode by combining a set of nodes. Then a greedy method is presented to partition those supernodes through working on the low-rank matrix. Instead of removing the longest edges from MST, our algorithm groups the data set based on the minimax similarity. Finally, the assignment of all data points can be achieved through their corresponding supernodes. Experimental results on many synthetic and real-world data sets show that our algorithm consistently outperforms compared clustering algorithms.

Statistical Irreversible Thermodynamics in the Framework of Zubarev's Nonequilibrium Statistical Operator Method

NASA Astrophysics Data System (ADS)

Luzzi, R.; Vasconcellos, A. R.; Ramos, J. G.; Rodrigues, C. G.

2018-01-01

We describe the formalism of statistical irreversible thermodynamics constructed based on Zubarev's nonequilibrium statistical operator (NSO) method, which is a powerful and universal tool for investigating the most varied physical phenomena. We present brief overviews of the statistical ensemble formalism and statistical irreversible thermodynamics. The first can be constructed either based on a heuristic approach or in the framework of information theory in the Jeffreys-Jaynes scheme of scientific inference; Zubarev and his school used both approaches in formulating the NSO method. We describe the main characteristics of statistical irreversible thermodynamics and discuss some particular considerations of several authors. We briefly describe how Rosenfeld, Bohr, and Prigogine proposed to derive a thermodynamic uncertainty principle.

High-Throughput Thermodynamic Modeling and Uncertainty Quantification for ICME

NASA Astrophysics Data System (ADS)

Otis, Richard A.; Liu, Zi-Kui

2017-05-01

One foundational component of the integrated computational materials engineering (ICME) and Materials Genome Initiative is the computational thermodynamics based on the calculation of phase diagrams (CALPHAD) method. The CALPHAD method pioneered by Kaufman has enabled the development of thermodynamic, atomic mobility, and molar volume databases of individual phases in the full space of temperature, composition, and sometimes pressure for technologically important multicomponent engineering materials, along with sophisticated computational tools for using the databases. In this article, our recent efforts will be presented in terms of developing new computational tools for high-throughput modeling and uncertainty quantification based on high-throughput, first-principles calculations and the CALPHAD method along with their potential propagations to downstream ICME modeling and simulations.

Predicate calculus, artificial intelligence, and workers' compensation.

PubMed

Harber, P; McCoy, J M

1989-05-01

Application of principles of predicate calculus (PC) and artificial intelligence (AI) search methods to occupational medicine can meet several goals. First, they can improve understanding of the diagnostic process and recognition of the sources of uncertainty in knowledge and in case specific information. Second, PC provides a rational means of resolving differences in conclusion based upon the same premises. Third, understanding of these principles allows separation of knowledge (facts) from the process by which they are used and therefore facilitates development of AI-based expert systems. Application of PC to recognizing causation of pulmonary fibrosis is demonstrated in this paper, providing a method that can be generalized to other problems in occupational medicine. Application of PC and understanding of AI search routines may be particularly applicable to workers' compensation where explicit statement of rational and inferential process is necessary. This approach is useful in the diagnosis of occupational lung disease and may be particularly valuable in workers' compensation considerations, wherein explicit statement of rationale is needed.

First-principles analysis of anharmonic nuclear motion and thermal transport in thermoelectric materials

NASA Astrophysics Data System (ADS)

Tadano, Terumasa; Tsuneyuki, Shinji

2015-12-01

We show a first-principles approach for analyzing anharmonic properties of lattice vibrations in solids. We firstly extract harmonic and anharmonic force constants from accurate first-principles calculations based on the density functional theory. Using the many-body perturbation theory of phonons, we then estimate the phonon scattering probability due to anharmonic phonon-phonon interactions. We show the validity of the approach by computing the lattice thermal conductivity of Si, a typical covalent semiconductor, and selected thermoelectric materials PbTe and Bi2Te3 based on the Boltzmann transport equation. We also show that the phonon lifetime and the lattice thermal conductivity of the high-temperature phase of SrTiO3 can be estimated by employing the perturbation theory on top of the solution of the self-consistent phonon equation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faizal, Mir, E-mail: f2mir@uwaterloo.ca; Majumder, Barun, E-mail: barunbasanta@iitgn.ac.in

In this paper, we will incorporate the generalized uncertainty principle into field theories with Lifshitz scaling. We will first construct both bosonic and fermionic theories with Lifshitz scaling based on generalized uncertainty principle. After that we will incorporate the generalized uncertainty principle into a non-abelian gauge theory with Lifshitz scaling. We will observe that even though the action for this theory is non-local, it is invariant under local gauge transformations. We will also perform the stochastic quantization of this Lifshitz fermionic theory based generalized uncertainty principle.

A first principles calculation and statistical mechanics modeling of defects in Al-H system

NASA Astrophysics Data System (ADS)

Ji, Min; Wang, Cai-Zhuang; Ho, Kai-Ming

2007-03-01

The behavior of defects and hydrogen in Al was investigated by first principles calculations and statistical mechanics modeling. The formation energy of different defects in Al+H system such as Al vacancy, H in institution and multiple H in Al vacancy were calculated by first principles method. Defect concentration in thermodynamical equilibrium was studied by total free energy calculation including configuration entropy and defect-defect interaction from low concentration limit to hydride limit. In our grand canonical ensemble model, hydrogen chemical potential under different environment plays an important role in determing the defect concentration and properties in Al-H system.

Environment-dependent interfacial strength using first principles thermodynamics: The example of the Pt-HfO2 interface

NASA Astrophysics Data System (ADS)

Cardona Quintero, Y.; Ramanath, Ganpati; Ramprasad, R.

2013-10-01

A parameter-free, quantitative, first-principles methodology to determine the environment-dependent interfacial strength of metal-metal oxide interfaces is presented. This approach uses the notion of the weakest link to identify the most likely cleavage plane, and first principles thermodynamics to calculate the average work of separation as a function of the environment (in this case, temperature and oxygen pressure). The method is applied to the case of the Pt-HfO2 interface, and it is shown that the computed environment-dependent work of separation is in quantitative agreement with available experimental data.

Development of Long-term Datasets from Satellite BUV Instruments: The "Soft" Calibration Approach

NASA Technical Reports Server (NTRS)

Bhartia, Pawan K.; Taylor, Steven; Jaross, Glen

2005-01-01

The first BUV instrument was launched in April 1970 on NASA's Nimbus4 satellite. More than a dozen instruments, broadly based on the same principle, but using very different technologies, have been launched in the last 35 years on NASA, NOAA, Japanese and European satellites. In this paper we describe the basic principles of the "soft" calibration approach that we have successfully applied to the data from many of these instruments to produce a consistent long-term record of total ozone, ozone profile and aerosols. This approach is based on using accurate radiative transfer models and assumed/known properties of the atmosphere in ultraviolet to derive calibration parameters. Although the accuracy of the results inevitably depends upon how well the assumed atmospheric properties are known, the technique has several built-in cross- checks that improve the robustness of the method. To develop further confidence in the data the soft calibration technique can be combined with data collected from few well- calibrated ground-based instruments. We will use examples from past and present BUV instruments to show how the method works.

Developing Contingent Funding Methods for the Partnership for Excellence: A Chancellor's Office Working Paper.

ERIC Educational Resources Information Center

Nussbaum, Thomas J.; Cabaldon, Christopher L.

This document discusses the principles that guide the development of the contingent funding methods and the implementation criteria for the Partnership for Excellence Program, as well as significant issues and questions for the system to resolve. The first principle states that the level and pace of progress toward the Partnership goals are not…

General method of solving the Schroedinger equation of atoms and molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakatsuji, Hiroshi

2005-12-15

We propose a general method of solving the Schroedinger equation of atoms and molecules. We first construct the wave function having the exact structure, using the ICI (iterative configuration or complement interaction) method and then optimize the variables involved by the variational principle. Based on the scaled Schroedinger equation and related principles, we can avoid the singularity problem of atoms and molecules and formulate a general method of calculating the exact wave functions in an analytical expansion form. We choose initial function {psi}{sub 0} and scaling g function, and then the ICI method automatically generates the wave function that hasmore » the exact structure by using the Hamiltonian of the system. The Hamiltonian contains all the information of the system. The free ICI method provides a flexible and variationally favorable procedure of constructing the exact wave function. We explain the computational procedure of the analytical ICI method routinely performed in our laboratory. Simple examples are given using hydrogen atom for the nuclear singularity case, the Hooke's atom for the electron singularity case, and the helium atom for both cases.« less

Design of a Blended Learning Environment Based on Merrill’s Principles

NASA Astrophysics Data System (ADS)

Simarmata, Janner; Djohar, Asari; Purba, Janulis; Juanda, Enjang A.

2018-01-01

Designing blended learning courses requires a systematic approach, in instructional design decisions and implementations, instructional principles help educators not only to specify the elements of the course, but also to provide a solid base from which to build the technology. The blended learning course was designed based on Merrill’s First Principles of Instruction with five phases. This paper helps inform educators about how to develop appropriate learning styles and preferences according to students’ learning needs.

An Overview on Perception and Its Principles from Avicenna's Point of View

ERIC Educational Resources Information Center

Soltani, Ali Reza

2015-01-01

The main purpose this paper attempts to reach is to recognize principles of perception, its dimensions and types from Avicenna's point of view. This study is a qualitative study conducted using descriptive-analytical methods. Resources are first reviewed and principles of perception along with its process are extracted from his perspective.…

Structural phases arising from reconstructive and isostructural transitions in high-melting-point oxides under hydrostatic pressure: A first-principles study

NASA Astrophysics Data System (ADS)

Tian, Hao; Kuang, Xiao-Yu; Mao, Ai-Jie; Yang, Yurong; Xu, Changsong; Sayedaghaee, S. Omid; Bellaiche, L.

2018-01-01

High-melting-point oxides of chemical formula A B O3 with A =Ca , Sr, Ba and B =Zr , Hf are investigated as a function of hydrostatic pressure up to 200 GPa by combining first-principles calculations with a particle swarm optimization method. Ca- and Sr-based systems: (1) first undergo a reconstructive phase transition from a perovskite state to a novel structure that belongs to the post-post-perovskite family and (2) then experience an isostructural transition to a second, also new post-post-perovskite state at higher pressures, via the sudden formation of a specific out-of-plane B -O bond. In contrast, the studied Ba compounds evolve from a perovskite phase to a third novel post-post-perovskite structure via another reconstructive phase transition. The original characteristics of these three different post-post-perovskite states are emphasized. Unusual electronic properties, including significant piezochromic effects and an insulator-metal transition, are also reported and explained.

A martial arts exploration of elbow anatomy: Ikkyo (Aikido's first teaching).

PubMed

Seitz, F C; Olson, G D; Stenzel, T E

1991-12-01

The Martial Art of Aikido, based on several effective anatomical principles, is used to subdue a training partner. One of these methods is Ikkyo (First Teaching). According to Saotome, the original intent of Ikkyo was to "break the elbow joint" of an enemy. Nowadays the intent is to secure or pin a training partner to the mat. This investigation focused on examining Ikkyo with the purpose of describing the nerves, bones, and muscles involved in receiving this technique. Particular focus was placed on the locations and sources of the reported pain.

ChemMaps: Towards an approach for visualizing the chemical space based on adaptive satellite compounds

PubMed Central

Naveja, J. Jesús; Medina-Franco, José L.

2017-01-01

We present a novel approach called ChemMaps for visualizing chemical space based on the similarity matrix of compound datasets generated with molecular fingerprints’ similarity. The method uses a ‘satellites’ approach, where satellites are, in principle, molecules whose similarity to the rest of the molecules in the database provides sufficient information for generating a visualization of the chemical space. Such an approach could help make chemical space visualizations more efficient. We hereby describe a proof-of-principle application of the method to various databases that have different diversity measures. Unsurprisingly, we found the method works better with databases that have low 2D diversity. 3D diversity played a secondary role, although it seems to be more relevant as 2D diversity increases. For less diverse datasets, taking as few as 25% satellites seems to be sufficient for a fair depiction of the chemical space. We propose to iteratively increase the satellites number by a factor of 5% relative to the whole database, and stop when the new and the prior chemical space correlate highly. This Research Note represents a first exploratory step, prior to the full application of this method for several datasets. PMID:28794856

ChemMaps: Towards an approach for visualizing the chemical space based on adaptive satellite compounds.

PubMed

Naveja, J Jesús; Medina-Franco, José L

2017-01-01

We present a novel approach called ChemMaps for visualizing chemical space based on the similarity matrix of compound datasets generated with molecular fingerprints' similarity. The method uses a 'satellites' approach, where satellites are, in principle, molecules whose similarity to the rest of the molecules in the database provides sufficient information for generating a visualization of the chemical space. Such an approach could help make chemical space visualizations more efficient. We hereby describe a proof-of-principle application of the method to various databases that have different diversity measures. Unsurprisingly, we found the method works better with databases that have low 2D diversity. 3D diversity played a secondary role, although it seems to be more relevant as 2D diversity increases. For less diverse datasets, taking as few as 25% satellites seems to be sufficient for a fair depiction of the chemical space. We propose to iteratively increase the satellites number by a factor of 5% relative to the whole database, and stop when the new and the prior chemical space correlate highly. This Research Note represents a first exploratory step, prior to the full application of this method for several datasets.

Path integral Monte Carlo simulations of dense carbon-hydrogen plasmas

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Militzer, Burkhard; Benedict, Lorin X.; Soubiran, François; Sterne, Philip A.; Driver, Kevin P.

2018-03-01

Carbon-hydrogen plasmas and hydrocarbon materials are of broad interest to laser shock experimentalists, high energy density physicists, and astrophysicists. Accurate equations of state (EOSs) of hydrocarbons are valuable for various studies from inertial confinement fusion to planetary science. By combining path integral Monte Carlo (PIMC) results at high temperatures and density functional theory molecular dynamics results at lower temperatures, we compute the EOSs for hydrocarbons from simulations performed at 1473 separate (ρ, T)-points distributed over a range of compositions. These methods accurately treat electronic excitation effects with neither adjustable parameter nor experimental input. PIMC is also an accurate simulation method that is capable of treating many-body interaction and nuclear quantum effects at finite temperatures. These methods therefore provide a benchmark-quality EOS that surpasses that of semi-empirical and Thomas-Fermi-based methods in the warm dense matter regime. By comparing our first-principles EOS to the LEOS 5112 model for CH, we validate the specific heat assumptions in this model but suggest that the Grüneisen parameter is too large at low temperatures. Based on our first-principles EOSs, we predict the principal Hugoniot curve of polystyrene to be 2%-5% softer at maximum shock compression than that predicted by orbital-free density functional theory and SESAME 7593. By investigating the atomic structure and chemical bonding of hydrocarbons, we show a drastic decrease in the lifetime of chemical bonds in the pressure interval from 0.4 to 4 megabar. We find the assumption of linear mixing to be valid for describing the EOS and the shock Hugoniot curve of hydrocarbons in the regime of partially ionized atomic liquids. We make predictions of the shock compression of glow-discharge polymers and investigate the effects of oxygen content and C:H ratio on its Hugoniot curve. Our full suite of first-principles simulation results may be used to benchmark future theoretical investigations pertaining to hydrocarbon EOSs and should be helpful in guiding the design of future experiments on hydrocarbons in the gigabar regime.

Comparison between Two Linear Supervised Learning Machines' Methods with Principle Component Based Methods for the Spectrofluorimetric Determination of Agomelatine and Its Degradants.

PubMed

Elkhoudary, Mahmoud M; Naguib, Ibrahim A; Abdel Salam, Randa A; Hadad, Ghada M

2017-05-01

Four accurate, sensitive and reliable stability indicating chemometric methods were developed for the quantitative determination of Agomelatine (AGM) whether in pure form or in pharmaceutical formulations. Two supervised learning machines' methods; linear artificial neural networks (PC-linANN) preceded by principle component analysis and linear support vector regression (linSVR), were compared with two principle component based methods; principle component regression (PCR) as well as partial least squares (PLS) for the spectrofluorimetric determination of AGM and its degradants. The results showed the benefits behind using linear learning machines' methods and the inherent merits of their algorithms in handling overlapped noisy spectral data especially during the challenging determination of AGM alkaline and acidic degradants (DG1 and DG2). Relative mean squared error of prediction (RMSEP) for the proposed models in the determination of AGM were 1.68, 1.72, 0.68 and 0.22 for PCR, PLS, SVR and PC-linANN; respectively. The results showed the superiority of supervised learning machines' methods over principle component based methods. Besides, the results suggested that linANN is the method of choice for determination of components in low amounts with similar overlapped spectra and narrow linearity range. Comparison between the proposed chemometric models and a reported HPLC method revealed the comparable performance and quantification power of the proposed models.

Evidence-based health care: its place within clinical governance.

PubMed

McSherry, R; Haddock, J

This article explores the principles of evidence-based practice and its role in achieving quality improvements within the clinical governance framework advocated by the recent White Papers 'The New NHS: Modern, Dependable' (Department of Health (DoH), 1997) and 'A First Class Service: Quality in the New NHS' (DoH, 1998a). Within these White Papers there is an emphasis on improving quality of care, treatment and services through employing the principles of clinical governance. A major feature of clinical governance is guaranteeing quality to the public and the NHS, and ensuring that clinical, managerial and educational practice is based on scientific evidence. This article also examines what evidence-based practice is and what processes are required to promote effective healthcare interventions. The authors also look at how clinical governance relates to other methods/systems involved in clinical effectiveness. Finally, the importance for nurses and other healthcare professionals of familiarizing themselves with the development of critical appraisal skills, and their implications for developing evidence-based practice, is emphasized.

Diffusion in thorium carbide: A first-principles study

NASA Astrophysics Data System (ADS)

Pérez Daroca, D.; Llois, A. M.; Mosca, H. O.

2015-12-01

The prediction of the behavior of Th compounds under irradiation is an important issue for the upcoming Generation-IV nuclear reactors. The study of self-diffusion and hetero-diffusion is a central key to fulfill this goal. As a first approach, we obtained, by means of first-principles methods, migration and activation energies of Th and C atoms self-diffusion and diffusion of He atoms in ThC. We also calculate diffusion coefficients as a function of temperature.

SU-E-T-191: First Principle Calculation of Quantum Yield in Photodynamic Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abolfath, R; Guo, F; Chen, Z

Purpose: We present a first-principle method to calculate the spin transfer efficiency in oxygen induced by any photon fields especially in MeV energy range. The optical pumping is mediated through photosensitizers, e.g., porphyrin and/or ensemble of quantum dots. Methods: Under normal conditions, oxygen molecules are in the relatively non-reactive triplet state. In the presence of certain photosensitizer compounds such as porphyrins, electromagnetic radiation of specific wavelengths can excite oxygen to highly reactive singlet state. With selective uptake of photosensitizers by certain malignant cells, photon irradiation of phosensitized tumors can lead to selective killing of cancer cells. This is the basismore » of photodynamic therapy (PDT). Despite several attempts, PDT has not been clinically successful except in limited superficial cancers. Many parameters such as photon energy, conjugation with quantum dots etc. can be potentially combined with PDT in order to extend the role of PDT in cancer management. The key quantity for this optimization is the spin transfer efficiency in oxygen by any photon field. The first principle calculation model presented here, is an attempt to fill this need. We employ stochastic density matrix description of the quantum jumps and the rate equation methods in quantum optics based on Markov/Poisson processes and calculate time evolution of the population of the optically pumped singlet oxygen. Results: The results demonstrate the feasibility of our model in showing the dependence of the optical yield in generating spin-singlet oxygen on the experimental conditions. The adjustable variables can be tuned to maximize the population of the singlet oxygen hence the efficacy of the photodynamic therapy. Conclusion: The present model can be employed to fit and analyze the experimental data and possibly to assist researchers in optimizing the experimental conditions in photodynamic therapy.« less

7 CFR 1767.13 - Departures from the prescribed RUS Uniform System of Accounts.

Code of Federal Regulations, 2010 CFR

2010-01-01

... accounting methodologies and principles that depart from the provisions herein; or (2) File with such... borrower's rates, based upon accounting methods and principles inconsistent with the provisions of this... accounting methods or principles for the borrower that are inconsistent with the provisions of this part, the...

A synthetic method of solar spectrum based on LED

NASA Astrophysics Data System (ADS)

Wang, Ji-qiang; Su, Shi; Zhang, Guo-yu; Zhang, Jian

2017-10-01

A synthetic method of solar spectrum which based on the spectral characteristics of the solar spectrum and LED, and the principle of arbitrary spectral synthesis was studied by using 14 kinds of LED with different central wavelengths.The LED and solar spectrum data were selected by Origin Software firstly, then calculated the total number of LED for each center band by the transformation relation between brightness and illumination and Least Squares Curve Fit in Matlab.Finally, the spectrum curve of AM1.5 standard solar spectrum was obtained. The results met the technical indexes of the solar spectrum matching with ±20% and the solar constant with >0.5.

Determination of structure and properties of molecular crystals from first principles.

PubMed

Szalewicz, Krzysztof

2014-11-18

CONSPECTUS: Until recently, it had been impossible to predict structures of molecular crystals just from the knowledge of the chemical formula for the constituent molecule(s). A solution of this problem has been achieved using intermolecular force fields computed from first principles. These fields were developed by calculating interaction energies of molecular dimers and trimers using an ab initio method called symmetry-adapted perturbation theory (SAPT) based on density-functional theory (DFT) description of monomers [SAPT(DFT)]. For clusters containing up to a dozen or so atoms, interaction energies computed using SAPT(DFT) are comparable in accuracy to the results of the best wave function-based methods, whereas the former approach can be applied to systems an order of magnitude larger than the latter. In fact, for monomers with a couple dozen atoms, SAPT(DFT) is about equally time-consuming as the supermolecular DFT approach. To develop a force field, SAPT(DFT) calculations are performed for a large number of dimer and possibly also trimer configurations (grid points in intermolecular coordinates), and the interaction energies are then fitted by analytic functions. The resulting force fields can be used to determine crystal structures and properties by applying them in molecular packing, lattice energy minimization, and molecular dynamics calculations. In this way, some of the first successful determinations of crystal structures were achieved from first principles, with crystal densities and lattice parameters agreeing with experimental values to within about 1%. Crystal properties obtained using similar procedures but empirical force fields fitted to crystal data have typical errors of several percent due to low sensitivity of empirical fits to interactions beyond those of the nearest neighbors. The first-principles approach has additional advantages over the empirical approach for notional crystals and cocrystals since empirical force fields can only be extrapolated to such cases. As an alternative to applying SAPT(DFT) in crystal structure calculations, one can use supermolecular DFT interaction energies combined with scaled dispersion energies computed from simple atom-atom functions, that is, use the so-called DFT+D approach. Whereas the standard DFT methods fail for intermolecular interactions, DFT+D performs reasonably well since the dispersion correction is used not only to provide the missing dispersion contribution but also to fix other deficiencies of DFT. The latter cancellation of errors is unphysical and can be avoided by applying the so-called dispersionless density functional, dlDF. In this case, the dispersion energies are added without any scaling. The dlDF+D method is also one of the best performing DFT+D methods. The SAPT(DFT)-based approach has been applied so far only to crystals with rigid monomers. It can be extended to partly flexible monomers, that is, to monomers with only a few internal coordinates allowed to vary. However, the costs will increase relative to rigid monomer cases since the number of grid points increases exponentially with the number of dimensions. One way around this problem is to construct force fields with approximate couplings between inter- and intramonomer degrees of freedom. Another way is to calculate interaction energies (and possibly forces) "on the fly", i.e., in each step of lattice energy minimization procedure. Such an approach would be prohibitively expensive if it replaced analytic force fields at all stages of the crystal predictions procedure, but it can be used to optimize a few dozen candidate structures determined by other methods.

Properties of amorphous GaN from first-principles simulations

NASA Astrophysics Data System (ADS)

Cai, B.; Drabold, D. A.

2011-08-01

Amorphous GaN (a-GaN) models are obtained from first-principles simulations. We compare four a-GaN models generated by “melt-and-quench” and the computer alchemy method. We find that most atoms tend to be fourfold, and a chemically ordered continuous random network is the ideal structure for a-GaN albeit with some coordination defects. Where the electronic structure is concerned, the gap is predicted to be less than 1.0 eV, underestimated as usual by a density functional calculation. We observe a highly localized valence tail and a remarkably delocalized exponential conduction tail in all models generated. Based upon these results, we speculate on potential differences in n- and p-type doping. The structural origin of tail and defect states is discussed. The vibrational density of states and dielectric function are computed and seem consistent with experiment.

First-Principle Study of the Optical Properties of Dilute-P GaN1-xPx Alloys.

PubMed

Borovac, Damir; Tan, Chee-Keong; Tansu, Nelson

2018-04-16

An investigation on the optical properties of dilute-P GaN 1-x P x alloys by First-Principle Density Functional Theory (DFT) methods is presented, for phosphorus (P) content varying from 0% up to 12.5%. Findings on the imaginary and real part of the dielectric function are analyzed and the results are compared with previously reported theoretical works on GaN. The complex refractive index, normal-incidence reflectivity and birefringence are presented and a difference in the refractive index in the visible regime between GaN and GaNP alloys of ~0.3 can be engineered by adding minute amounts of phosphorus, indicating strong potential for refractive index tunability. The optical properties of the GaN 1-x P x alloys indicate their strong potential for implementation in various III-nitride-based photonic waveguide applications and Distributed Bragg Reflectors (DBR).

First principles calculation for Gilbert damping constants in ferromagnetic/non-magnetic junctions

NASA Astrophysics Data System (ADS)

Hiramatsu, R.; Miura, D.; Sakuma, A.

2018-05-01

We evaluated an intrinsic α in ferromagnetic (FM)/non-magnetic (NM) junctions from first principles (FM = Co, Fe, and Ni and NM = Cu, Pd, and Pt) to investigate the effects of the inserted NM layer. α is calculated by liner muffin-tin orbital methods based on the torque-correlation model. We confirmed that Gilbert damping is enhanced and saturated as NM thickness increases, and that the enhancement is greater in NM materials having a stronger spin-orbital interaction. By contrast, the calculated FM thickness dependences of α show that Gilbert damping tends to decrease and be saturated as the FM thickness increases. Under the torque-correlation model, the dependences of α on FM and NM thickness can be explained by considering the electronic structure of the total system, including junction interfaces, which exhibit similar behaviors derived by spin pumping theory.

First principles calculations of thermal conductivity with out of equilibrium molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Puligheddu, Marcello; Gygi, Francois; Galli, Giulia

The prediction of the thermal properties of solids and liquids is central to numerous problems in condensed matter physics and materials science, including the study of thermal management of opto-electronic and energy conversion devices. We present a method to compute the thermal conductivity of solids by performing ab initio molecular dynamics at non equilibrium conditions. Our formulation is based on a generalization of the approach to equilibrium technique, using sinusoidal temperature gradients, and it only requires calculations of first principles trajectories and atomic forces. We discuss results and computational requirements for a representative, simple oxide, MgO, and compare with experiments and data obtained with classical potentials. This work was supported by MICCoM as part of the Computational Materials Science Program funded by the U.S. Department of Energy (DOE), Office of Science , Basic Energy Sciences (BES), Materials Sciences and Engineering Division under Grant DOE/BES 5J-30.

The effects of alloying elements Al and In on Ni-Mn-Ga shape memory alloys, from first principles.

PubMed

Chen, Jie; Li, Yan; Shang, Jia-Xiang; Xu, Hui-Bin

2009-01-28

The electronic structures and formation energies of the Ni(9)Mn(4)Ga(3-x)Al(x) and Ni(9)Mn(4)Ga(3-x)In(x) alloys have been investigated using the first-principles pseudopotential plane-wave method based on density functional theory. The results show that both the austenite and martensite phases of Ni(9)Mn(4)Ga(3) alloy are stabilized by Al alloying, while they become unstable with In alloying. According to the partial density of states and structural energy analysis, different effects of Al and In alloying on the phase stability are mainly attributed to their chemical effects. The formation energy difference between the austenite and martensite phases decreases with Al or In alloying, correlating with the experimentally reported changes in martensitic transformation temperature. The shape factor plays an important role in the decrease of the formation energy difference.

Experimental and first principle studies on electronic structure of BaTiO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sagdeo, Archna, E-mail: archnaj@rrcat.gov.in; Ghosh, Haranath, E-mail: archnaj@rrcat.gov.in; Chakrabarti, Aparna, E-mail: archnaj@rrcat.gov.in

2014-04-24

We have carried out photoemission experiments to obtain valence band spectra of various crystallographic symmetries of BaTiO{sub 3} system which arise as a function of temperature. We also present results of a detailed first principle study of these symmetries of BaTiO{sub 3} using generalized gradient approximation for the exchange-correlation potential. Here we present theoretical results of density of states obtained from DFT based simulations to compare with the experimental valence band spectra. Further, we also perform calculations using post density functional approaches like GGA + U method as well as non-local hybrid exchange-correlation potentials like PBE0, B3LYP, HSE in ordermore » to understand the extent of effect of correlation on band gaps of different available crystallographic symmetries (5 in number) of BaTiO{sub 3}.« less

Introduction to COFFE: The Next-Generation HPCMP CREATE-AV CFD Solver

NASA Technical Reports Server (NTRS)

Glasby, Ryan S.; Erwin, J. Taylor; Stefanski, Douglas L.; Allmaras, Steven R.; Galbraith, Marshall C.; Anderson, W. Kyle; Nichols, Robert H.

2016-01-01

HPCMP CREATE-AV Conservative Field Finite Element (COFFE) is a modular, extensible, robust numerical solver for the Navier-Stokes equations that invokes modularity and extensibility from its first principles. COFFE implores a flexible, class-based hierarchy that provides a modular approach consisting of discretization, physics, parallelization, and linear algebra components. These components are developed with modern software engineering principles to ensure ease of uptake from a user's or developer's perspective. The Streamwise Upwind/Petrov-Galerkin (SU/PG) method is utilized to discretize the compressible Reynolds-Averaged Navier-Stokes (RANS) equations tightly coupled with a variety of turbulence models. The mathematics and the philosophy of the methodology that makes up COFFE are presented.

Structural, electronic and magnetic properties of Pr-based filled skutterudites: A first principle study

NASA Astrophysics Data System (ADS)

Yadav, Priya; Nautiyal, Shashank; Verma, U. P.

2018-04-01

Ternary skutterudites materials exhibit good electronic properties due to the unpaired d- and f- electrons of the transition and rare-earth metals, respectively. In this communication, we have performed the structural optimization of Pr-based filled skutterudite (PrCo4P12) for the first time and obtained the electronic band structure, density of states and magnetic moments by using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). Our obtained magnetic moment of PrCo4P12 is ˜ 1.8 µB in which main contribution is due to Pr atom. Behavior of this material is metallic and it is most stable in body centered cubic (BCC) structure.

Validation of a multi-criteria evaluation model for animal welfare.

PubMed

Martín, P; Czycholl, I; Buxadé, C; Krieter, J

2017-04-01

The aim of this paper was to validate an alternative multi-criteria evaluation system to assess animal welfare on farms based on the Welfare Quality® (WQ) project, using an example of welfare assessment of growing pigs. This alternative methodology aimed to be more transparent for stakeholders and more flexible than the methodology proposed by WQ. The WQ assessment protocol for growing pigs was implemented to collect data in different farms in Schleswig-Holstein, Germany. In total, 44 observations were carried out. The aggregation system proposed in the WQ protocol follows a three-step aggregation process. Measures are aggregated into criteria, criteria into principles and principles into an overall assessment. This study focussed on the first two steps of the aggregation. Multi-attribute utility theory (MAUT) was used to produce a value of welfare for each criterion and principle. The utility functions and the aggregation function were constructed in two separated steps. The MACBETH (Measuring Attractiveness by a Categorical-Based Evaluation Technique) method was used for utility function determination and the Choquet integral (CI) was used as an aggregation operator. The WQ decision-makers' preferences were fitted in order to construct the utility functions and to determine the CI parameters. The validation of the MAUT model was divided into two steps, first, the results of the model were compared with the results of the WQ project at criteria and principle level, and second, a sensitivity analysis of our model was carried out to demonstrate the relative importance of welfare measures in the different steps of the multi-criteria aggregation process. Using the MAUT, similar results were obtained to those obtained when applying the WQ protocol aggregation methods, both at criteria and principle level. Thus, this model could be implemented to produce an overall assessment of animal welfare in the context of the WQ protocol for growing pigs. Furthermore, this methodology could also be used as a framework in order to produce an overall assessment of welfare for other livestock species. Two main findings are obtained from the sensitivity analysis, first, a limited number of measures had a strong influence on improving or worsening the level of welfare at criteria level and second, the MAUT model was not very sensitive to an improvement in or a worsening of single welfare measures at principle level. The use of weighted sums and the conversion of disease measures into ordinal scores should be reconsidered.

Forward and inverse models of electromagnetic scattering from layered media with rough interfaces

NASA Astrophysics Data System (ADS)

Tabatabaeenejad, Seyed Alireza

This work addresses the problem of electromagnetic scattering from layered dielectric structures with rough boundaries and the associated inverse problem of retrieving the subsurface parameters of the structure using the scattered field. To this end, a forward scattering model based on the Small Perturbation Method (SPM) is developed to calculate the first-order spectral-domain bistatic scattering coefficients of a two-layer rough surface structure. SPM requires the boundaries to be slightly rough compared to the wavelength, but to understand the range of applicability of this method in scattering from two-layer rough surfaces, its region of validity is investigated by comparing its output with that of a first principle solver that does not impose roughness restrictions. The Method of Moments (MoM) is used for this purpose. Finally, for retrieval of the model parameters of the layered structure using scattered field, an inversion scheme based on the Simulated Annealing method is investigated and a strategy is proposed to address convergence to local minimum.

First principles molecular dynamics of molten NaCl

NASA Astrophysics Data System (ADS)

Galamba, N.; Costa Cabral, B. J.

2007-03-01

First principles Hellmann-Feynman molecular dynamics (HFMD) results for molten NaCl at a single state point are reported. The effect of induction forces on the structure and dynamics of the system is studied by comparison of the partial radial distribution functions and the velocity and force autocorrelation functions with those calculated from classical MD based on rigid-ion and shell-model potentials. The first principles results reproduce the main structural features of the molten salt observed experimentally, whereas they are incorrectly described by both rigid-ion and shell-model potentials. Moreover, HFMD Green-Kubo self-diffusion coefficients are in closer agreement with experimental data than those predicted by classical MD. A comprehensive discussion of MD results for molten NaCl based on different ab initio parametrized polarizable interionic potentials is also given.

A white-box model of S-shaped and double S-shaped single-species population growth

PubMed Central

Kalmykov, Lev V.

2015-01-01

Complex systems may be mechanistically modelled by white-box modeling with using logical deterministic individual-based cellular automata. Mathematical models of complex systems are of three types: black-box (phenomenological), white-box (mechanistic, based on the first principles) and grey-box (mixtures of phenomenological and mechanistic models). Most basic ecological models are of black-box type, including Malthusian, Verhulst, Lotka–Volterra models. In black-box models, the individual-based (mechanistic) mechanisms of population dynamics remain hidden. Here we mechanistically model the S-shaped and double S-shaped population growth of vegetatively propagated rhizomatous lawn grasses. Using purely logical deterministic individual-based cellular automata we create a white-box model. From a general physical standpoint, the vegetative propagation of plants is an analogue of excitation propagation in excitable media. Using the Monte Carlo method, we investigate a role of different initial positioning of an individual in the habitat. We have investigated mechanisms of the single-species population growth limited by habitat size, intraspecific competition, regeneration time and fecundity of individuals in two types of boundary conditions and at two types of fecundity. Besides that, we have compared the S-shaped and J-shaped population growth. We consider this white-box modeling approach as a method of artificial intelligence which works as automatic hyper-logical inference from the first principles of the studied subject. This approach is perspective for direct mechanistic insights into nature of any complex systems. PMID:26038717

On the need and use of models to explore the role of economic confidence:a survey.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprigg, James A.; Paez, Paul J.; Hand, Michael S.

2005-04-01

Empirical studies suggest that consumption is more sensitive to current income than suggested under the permanent income hypothesis, which raises questions regarding expectations for future income, risk aversion, and the role of economic confidence measures. This report surveys a body of fundamental economic literature as well as burgeoning computational modeling methods to support efforts to better anticipate cascading economic responses to terrorist threats and attacks. This is a three part survey to support the incorporation of models of economic confidence into agent-based microeconomic simulations. We first review broad underlying economic principles related to this topic. We then review the economicmore » principle of confidence and related empirical studies. Finally, we provide a brief survey of efforts and publications related to agent-based economic simulation.« less

Role of Logic and Mentality as the Basics of Wittgenstein's Picture Theory of Language and Extracting Educational Principles and Methods According to This Theory

ERIC Educational Resources Information Center

Heshi, Kamal Nosrati; Nasrabadi, Hassanali Bakhtiyar

2016-01-01

The present paper attempts to recognize principles and methods of education based on Wittgenstein's picture theory of language. This qualitative research utilized inferential analytical approach to review the related literature and extracted a set of principles and methods from his theory on picture language. Findings revealed that Wittgenstein…

A Quadruped Micro-Robot Based on Piezoelectric Driving

PubMed Central

Su, Qi; Quan, Qiquan; Deng, Jie; Yu, Hongpeng

2018-01-01

Inspired by a way of rowing, a new piezoelectric driving quadruped micro-robot operating in bending-bending hybrid vibration modes was proposed and tested in this work. The robot consisted of a steel base, four steel connecting pins and four similar driving legs, and all legs were bonded by four piezoelectric ceramic plates. The driving principle is discussed, which is based on the hybrid of first order vertical bending and first order horizontal bending vibrations. The bending-bending hybrid vibration modes motivated the driving foot to form an elliptical trajectory in space. The vibrations of four legs were used to provide the driving forces for robot motion. The proposed robot was fabricated and tested according to driving principle. The vibration characteristics and elliptical movements of the driving feet were simulated by FEM method. Experimental tests of vibration characteristics and mechanical output abilities were carried out. The tested resonance frequencies and vibration amplitudes agreed well with the FEM calculated results. The size of robot is 36 mm × 98 mm × 14 mm, its weight is only 49.8 g, but its maximum load capacity achieves 200 g. Furthermore, the robot can achieve a maximum speed of 33.45 mm/s. PMID:29518964

A Quadruped Micro-Robot Based on Piezoelectric Driving.

PubMed

Su, Qi; Quan, Qiquan; Deng, Jie; Yu, Hongpeng

2018-03-07

Inspired by a way of rowing, a new piezoelectric driving quadruped micro-robot operating in bending-bending hybrid vibration modes was proposed and tested in this work. The robot consisted of a steel base, four steel connecting pins and four similar driving legs, and all legs were bonded by four piezoelectric ceramic plates. The driving principle is discussed, which is based on the hybrid of first order vertical bending and first order horizontal bending vibrations. The bending-bending hybrid vibration modes motivated the driving foot to form an elliptical trajectory in space. The vibrations of four legs were used to provide the driving forces for robot motion. The proposed robot was fabricated and tested according to driving principle. The vibration characteristics and elliptical movements of the driving feet were simulated by FEM method. Experimental tests of vibration characteristics and mechanical output abilities were carried out. The tested resonance frequencies and vibration amplitudes agreed well with the FEM calculated results. The size of robot is 36 mm × 98 mm × 14 mm, its weight is only 49.8 g, but its maximum load capacity achieves 200 g. Furthermore, the robot can achieve a maximum speed of 33.45 mm/s.

High-Performance Solid-State Thermionic Energy Conversion Based on 2D van der Waals Heterostructures: A First-Principles Study.

PubMed

Wang, Xiaoming; Zebarjadi, Mona; Esfarjani, Keivan

2018-06-18

Two-dimensional (2D) van der Waals heterostructures (vdWHs) have shown multiple functionalities with great potential in electronics and photovoltaics. Here, we show their potential for solid-state thermionic energy conversion and demonstrate a designing strategy towards high-performance devices. We propose two promising thermionic devices, namely, the p-type Pt-G-WSe 2 -G-Pt and n-type Sc-WSe 2 -MoSe 2 -WSe 2 -Sc. We characterize the thermionic energy conversion performance of the latter using first-principles GW calculations combined with real space Green's function (GF) formalism. The optimal barrier height and high thermal resistance lead to an excellent performance. The proposed device is found to have a room temperature equivalent figure of merit of 1.2 which increases to 3 above 600 K. A high performance with cooling efficiency over 30% of the Carnot efficiency above 450 K is achieved. Our designing and characterization method can be used to pursue other potential thermionic devices based on vdWHs.

First-principles study of intermetallic phase stability in the ternary Ti-Al-Nb alloy system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asta, M.; Ormeci, A.; Wills, J.M.

The stability of bcc-based phases in the Ti-Al-Nb alloy system has been studied from first-principles using a combination of ab-initio total energy and cluster variation method (CVM) calculations. Total energies have been computed for 18 binary and ternary bcc superstructures in order to determine low temperature ordering tendencies. From the results of these calculations a set of effective cluster interaction parameters have been derived. These interaction parameters are required input for CVM computations of alloy thermodynamic properties. The CVM has been used to study the effect of composition on finite-temperature ordering tendencies and site preferences for bcc-based phases. Strong orderingmore » tendencies are observed for binary Nb-Al and Ti-Al bcc phases as well as for ternary alloys with compositions near Ti{sub 2}AlNb. For selected superstructures we have also analyzed structural stabilities with respect to tetragonal distortions which transform the bcc into an fcc lattice. Instabilities with respect to such distortions are found to exist for binary but not ternary bcc compounds.« less

A Method of Spatial Mapping and Reclassification for High-Spatial-Resolution Remote Sensing Image Classification

PubMed Central

Wang, Guizhou; Liu, Jianbo; He, Guojin

2013-01-01

This paper presents a new classification method for high-spatial-resolution remote sensing images based on a strategic mechanism of spatial mapping and reclassification. The proposed method includes four steps. First, the multispectral image is classified by a traditional pixel-based classification method (support vector machine). Second, the panchromatic image is subdivided by watershed segmentation. Third, the pixel-based multispectral image classification result is mapped to the panchromatic segmentation result based on a spatial mapping mechanism and the area dominant principle. During the mapping process, an area proportion threshold is set, and the regional property is defined as unclassified if the maximum area proportion does not surpass the threshold. Finally, unclassified regions are reclassified based on spectral information using the minimum distance to mean algorithm. Experimental results show that the classification method for high-spatial-resolution remote sensing images based on the spatial mapping mechanism and reclassification strategy can make use of both panchromatic and multispectral information, integrate the pixel- and object-based classification methods, and improve classification accuracy. PMID:24453808

78 FR 44627 - HOME Investment Partnerships Program: Improving Performance and Accountability; Updating Property...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-24

... (Faith-Based Activities) to reflect the amendments made by Executive Order 13559 (Fundamental Principles... several important values and principles of community development. First, the HOME program's flexibility is...

First principles calculation of two dimensional antimony and antimony arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pillai, Sharad Babu, E-mail: sbpillai001@gmail.com; Narayan, Som; Jha, Prafulla K.

2016-05-23

This work focuses on the strain dependence of the electronic properties of two dimensional antimony (Sb) material and its alloy with As (SbAs) using density functional theory based first principles calculations. Both systems show indirect bandgap semiconducting character which can be transformed into a direct bandgap material with the application of relatively small strain.

First principle study of structural, electronic and fermi surface properties of aluminum praseodymium

NASA Astrophysics Data System (ADS)

Shugani, Mani; Aynyas, Mahendra; Sanyal, S. P.

2018-05-01

We present a structural, Electronic and Fermi surface properties of Aluminum Praseodymium (AlPr) using First-principles density functional calculation by using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA). The ground state properties along with electronic and Fermi surface properties are studied. It is found that AlPr is metallic and the bonding between Al and Pr is covalent.

First Principles Model of Electric Cable Braid Penetration with Dielectrics

DOE PAGES

Campione, Salvatore; Warne, Larry Kevin; Langston, William L.; ...

2018-01-01

In this study, we report the formulation to account for dielectrics in a first principles multipole-based cable braid electromagnetic penetration model. To validate our first principles model, we consider a one-dimensional array of wires, which can be modeled analytically with a multipole-conformal mapping expansion for the wire charges; however, the first principles model can be readily applied to realistic cable geometries. We compare the elastance (i.e. the inverse of the capacitance) results from the first principles cable braid electromagnetic penetration model to those obtained using the analytical model. The results are found in good agreement up to a radius tomore » half spacing ratio of 0.5-0.6, depending on the permittivity of the dielectric used, within the characteristics of many commercial cables. We observe that for typical relative permittivities encountered in braided cables, the transfer elastance values are essentially the same as those of free space; the self-elastance values are also approximated by the free space solution as long as the dielectric discontinuity is taken into account for the planar mode.« less

First Principles Model of Electric Cable Braid Penetration with Dielectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campione, Salvatore; Warne, Larry Kevin; Langston, William L.

In this study, we report the formulation to account for dielectrics in a first principles multipole-based cable braid electromagnetic penetration model. To validate our first principles model, we consider a one-dimensional array of wires, which can be modeled analytically with a multipole-conformal mapping expansion for the wire charges; however, the first principles model can be readily applied to realistic cable geometries. We compare the elastance (i.e. the inverse of the capacitance) results from the first principles cable braid electromagnetic penetration model to those obtained using the analytical model. The results are found in good agreement up to a radius tomore » half spacing ratio of 0.5-0.6, depending on the permittivity of the dielectric used, within the characteristics of many commercial cables. We observe that for typical relative permittivities encountered in braided cables, the transfer elastance values are essentially the same as those of free space; the self-elastance values are also approximated by the free space solution as long as the dielectric discontinuity is taken into account for the planar mode.« less

First-Principles Studies of Structure-Property Relationships: Enabling Design of Functional Materials

NASA Astrophysics Data System (ADS)

Zhou, Qunfei

First-principles calculations based on quantum mechanics have been proved to be powerful for accurately regenerating experimental results, uncovering underlying myths of experimental phenomena, and accelerating the design of innovative materials. This work has been motivated by the demand to design next-generation thermionic emitting cathodes and techniques to allow for synthesis of photo-responsive polymers on complex surfaces with controlled thickness and patterns. For Os-coated tungsten thermionic dispenser cathodes, we used first-principles methods to explore the bulk and surface properties of W-Os alloys in order to explain the previously observed experimental phenomena that thermionic emission varies significantly with W-Os alloy composition. Meanwhile, we have developed a new quantum mechanical approach to quantitatively predict the thermionic emission current density from materials perspective without any semi-empirical approximations or complicated analytical models, which leads to better understanding of thermionic emission mechanism. The methods from this work could be used to accelerate the design of next-generation thermionic cathodes. For photoresponsive materials, we designed a novel type of azobenzene-containing monomer for light-mediated ring-opening metathesis polymerization (ROMP) toward the fabrication of patterned, photo-responsive polymers by controlling ring strain energy (RSE) of the monomer that drives ROMP. This allows for unprecedented remote, noninvasive, instantaneous spatial and temporal control of photo-responsive polymer deposition on complex surfaces.This work on the above two different materials systems showed the power of quantum mechanical calculations on predicting, understanding and discovering the structures and properties of both known and unknown materials in a fast, efficient and reliable way.

A theoretical investigation on optimal structures of ethane clusters (C2H6)n with n ≤ 25 and their building-up principle.

PubMed

Takeuchi, Hiroshi

2011-05-01

Geometry optimization of ethane clusters (C(2)H(6))(n) in the range of n ≤ 25 is carried out with a Morse potential. A heuristic method based on perturbations of geometries is used to locate global minima of the clusters. The following perturbations are carried out: (1) the molecule or group with the highest energy is moved to the interior of a cluster, (2) it is moved to stable positions on the surface of a cluster, and (3) orientations of one and two molecules are randomly modified. The geometry obtained after each perturbation is optimized by a quasi-Newton method. The global minimum of the dimer is consistent with that previously reported. The putative global minima of the clusters with 3 ≤ n ≤ 25 are first proposed and their building-up principle is discussed. Copyright © 2010 Wiley Periodicals, Inc.

Screening of the key volatile organic compounds of Tuber melanosporum fermentation by aroma sensory evaluation combination with principle component analysis

PubMed Central

Liu, Rui-Sang; Jin, Guang-Huai; Xiao, Deng-Rong; Li, Hong-Mei; Bai, Feng-Wu; Tang, Ya-Jie

2015-01-01

Aroma results from the interplay of volatile organic compounds (VOCs) and the attributes of microbial-producing aromas are significantly affected by fermentation conditions. Among the VOCs, only a few of them contribute to aroma. Thus, screening and identification of the key VOCs is critical for microbial-producing aroma. The traditional method is based on gas chromatography-olfactometry (GC-O), which is time-consuming and laborious. Considering the Tuber melanosporum fermentation system as an example, a new method to screen and identify the key VOCs by combining the aroma evaluation method with principle component analysis (PCA) was developed in this work. First, an aroma sensory evaluation method was developed to screen 34 potential favorite aroma samples from 504 fermentation samples. Second, PCA was employed to screen nine common key VOCs from these 34 samples. Third, seven key VOCs were identified by the traditional method. Finally, all of the seven key VOCs identified by the traditional method were also identified, along with four others, by the new strategy. These results indicate the reliability of the new method and demonstrate it to be a viable alternative to the traditional method. PMID:26655663

Protection Relaying Scheme Based on Fault Reactance Operation Type

NASA Astrophysics Data System (ADS)

Tsuji, Kouichi

The theories of operation of existing relays are roughly divided into two types: one is the current differential types based on Kirchhoff's first law and the other is impedance types based on second law. We can apply the Kirchhoff's laws to strictly formulate fault phenomena, so the circuit equations are represented non linear simultaneous equations with variables fault point k and fault resistance Rf. This method has next two defect. 1) heavy computational burden for the iterative calculation on N-R method, 2) relay operator can not easily understand principle of numerical matrix operation. The new protection relay principles we proposed this paper focuses on the fact that the reactance component on fault point is almost zero. Two reactance Xf(S), Xf(R) on branch both ends are calculated by operation of solving linear equations. If signs of Xf(S) and Xf(R) are not same, it can be judged that the fault point exist in the branch. This reactance Xf corresponds to difference of branch reactance between actual fault point and imaginaly fault point. And so relay engineer can to understand fault location by concept of “distance". The simulation results using this new method indicates the highly precise estimation of fault locations compared with the inspected fault locations on operating transmission lines.

The method of public morality versus the method of principlism.

PubMed

Green, R M; Gert, B; Clouser, K D

1993-10-01

Two years ago in two articles in a thematic issue of this journal the three of us engaged in a critique of principlism. In a subsequent issue, B. Andrew Lustig defended aspects of principlism we had criticized and argued against our own account of morality. Our reply to Lustig's critique is also in two parts, corresponding with his own. Our first part shows how Lustig's criticisms are seriously misdirected. Our second and philosophically more important part picks up on Lustig's challenge to us to show that our account of mortality is more adequate than principlism. In particular we show that recognition of mortality as public and systematic enables us to provide a far better description of morality than does principlism. This explains why we adopt the label "Dartmouth Descriptivism."

A method for detecting small targets based on cumulative weighted value of target properties

NASA Astrophysics Data System (ADS)

Jin, Xing; Sun, Gang; Wang, Wei-hua; Liu, Fang; Chen, Zeng-ping

2015-03-01

Laser detection based on the "cat's eye effect" has become the hot research project for its initiative compared to the passivity of sound detection and infrared detection. And the target detection is one of the core technologies in this system. The paper puts forward a method for detecting small targets based on cumulative weighted value of target properties using given data. Firstly, we make a frame difference to the images, then make image processing based on Morphology Principles. Secondly, we segment images, and screen the targets; then find some interesting locations. Finally, comparing to a quantity of frames, we locate the target. We did an exam to 394 true frames, the experimental result shows that the mathod can detect small targets efficiently.

[Profile of Shohei Ninomiya (pharmacist), the first Japanese medical representative to practice modern European-style propaganda in the late Meiji era].

PubMed

Nishikawa, Takashi

2007-01-01

A Swiss pharmaceutical company (F-Hoffmann-La Roche Ltd.), first introduced the profession of "propagandist" in Japan in 1912. At the time, Shohei Ninomiya was a chief hospital pharmacist, but he changed his vocation to become the first "propah" (Japanese abbreviation for propagandist). The German physician Dr. Rudolf Ebering initiated Dr. Ninomiya in the methods and principles of "propah," and he faithfully practiced them. The defining principle of a modern European propagandist is one who is far from sales-centered. From the late 1970s through 1980s, however, Japanese pharmaceutical companies indulged in pursuing sales and neglected this principle, resulting in numerous abuses and adverse effects. Today, use of the description "medical representative" (MR) is more common than "propah." Even with this different description, pharmaceutical companies and MRs should never neglect the founding principle to avoid repeating such abuses.

Achieving accuracy in first-principles calculations for EOS: basis completeness at high temperatures

NASA Astrophysics Data System (ADS)

Wills, John; Mattsson, Ann

2013-06-01

First-principles electronic structure calculations can provide EOS data in regimes of pressure and temperature where accurate experimental data is difficult or impossible to obtain. This lack, however, also precludes validation of calculations in those regimes. Factors that influence the accuracy of first-principles data include (1) theoretical approximations and (2) computational approximations used in implementing and solving the underlying equations. In the first category are the approximate exchange/correlation functionals and approximate wave equations approximating the Dirac equation; in the second are basis completeness, series convergence, and truncation errors. We are using two rather different electronic structure methods (VASP and RSPt) to make definitive the requirements for accuracy of the second type, common to both. In this talk, we discuss requirements for converged calculation at high temperature and moderated pressure. At convergence we show that both methods give identical results. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Research on regularized mean-variance portfolio selection strategy with modified Roy safety-first principle.

PubMed

Atta Mills, Ebenezer Fiifi Emire; Yan, Dawen; Yu, Bo; Wei, Xinyuan

2016-01-01

We propose a consolidated risk measure based on variance and the safety-first principle in a mean-risk portfolio optimization framework. The safety-first principle to financial portfolio selection strategy is modified and improved. Our proposed models are subjected to norm regularization to seek near-optimal stable and sparse portfolios. We compare the cumulative wealth of our preferred proposed model to a benchmark, S&P 500 index for the same period. Our proposed portfolio strategies have better out-of-sample performance than the selected alternative portfolio rules in literature and control the downside risk of the portfolio returns.

Macro-architectured cellular materials: Properties, characteristic modes, and prediction methods

NASA Astrophysics Data System (ADS)

Ma, Zheng-Dong

2017-12-01

Macro-architectured cellular (MAC) material is defined as a class of engineered materials having configurable cells of relatively large (i.e., visible) size that can be architecturally designed to achieve various desired material properties. Two types of novel MAC materials, negative Poisson's ratio material and biomimetic tendon reinforced material, were introduced in this study. To estimate the effective material properties for structural analyses and to optimally design such materials, a set of suitable homogenization methods was developed that provided an effective means for the multiscale modeling of MAC materials. First, a strain-based homogenization method was developed using an approach that separated the strain field into a homogenized strain field and a strain variation field in the local cellular domain superposed on the homogenized strain field. The principle of virtual displacements for the relationship between the strain variation field and the homogenized strain field was then used to condense the strain variation field onto the homogenized strain field. The new method was then extended to a stress-based homogenization process based on the principle of virtual forces and further applied to address the discrete systems represented by the beam or frame structures of the aforementioned MAC materials. The characteristic modes and the stress recovery process used to predict the stress distribution inside the cellular domain and thus determine the material strengths and failures at the local level are also discussed.

A Novel Physical Sensing Principle for Liquid Characterization Using Paper-Based Hygro-Mechanical Systems (PB-HMS).

PubMed

Perez-Cruz, Angel; Stiharu, Ion; Dominguez-Gonzalez, Aurelio

2017-07-20

In recent years paper-based microfluidic systems have emerged as versatile tools for developing sensors in different areas. In this work; we report a novel physical sensing principle for the characterization of liquids using a paper-based hygro-mechanical system (PB-HMS). The PB-HMS is formed by the interaction of liquid droplets and paper-based mini-structures such as cantilever beams. The proposed principle takes advantage of the hygroscopic properties of paper to produce hygro-mechanical motion. The dynamic response of the PB-HMS reveals information about the tested liquid that can be applied to characterize certain properties of liquids. A suggested method to characterize liquids by means of the proposed principle is introduced. The experimental results show the feasibility of such a method. It is expected that the proposed principle may be applied to sense properties of liquids in different applications where both disposability and portability are of extreme importance.

Missing value imputation in DNA microarrays based on conjugate gradient method.

PubMed

Dorri, Fatemeh; Azmi, Paeiz; Dorri, Faezeh

2012-02-01

Analysis of gene expression profiles needs a complete matrix of gene array values; consequently, imputation methods have been suggested. In this paper, an algorithm that is based on conjugate gradient (CG) method is proposed to estimate missing values. k-nearest neighbors of the missed entry are first selected based on absolute values of their Pearson correlation coefficient. Then a subset of genes among the k-nearest neighbors is labeled as the best similar ones. CG algorithm with this subset as its input is then used to estimate the missing values. Our proposed CG based algorithm (CGimpute) is evaluated on different data sets. The results are compared with sequential local least squares (SLLSimpute), Bayesian principle component analysis (BPCAimpute), local least squares imputation (LLSimpute), iterated local least squares imputation (ILLSimpute) and adaptive k-nearest neighbors imputation (KNNKimpute) methods. The average of normalized root mean squares error (NRMSE) and relative NRMSE in different data sets with various missing rates shows CGimpute outperforms other methods. Copyright © 2011 Elsevier Ltd. All rights reserved.

First-principles anharmonic quantum calculations for peptide spectroscopy: VSCF calculations and comparison with experiments.

PubMed

Roy, Tapta Kanchan; Sharma, Rahul; Gerber, R Benny

2016-01-21

First-principles quantum calculations for anharmonic vibrational spectroscopy of three protected dipeptides are carried out and compared with experimental data. Using hybrid HF/MP2 potentials, the Vibrational Self-Consistent Field with Second-Order Perturbation Correction (VSCF-PT2) algorithm is used to compute the spectra without any ad hoc scaling or fitting. All of the vibrational modes (135 for the largest system) are treated quantum mechanically and anharmonically using full pair-wise coupling potentials to represent the interaction between different modes. In the hybrid potential scheme the MP2 method is used for the harmonic part of the potential and a modified HF method is used for the anharmonic part. The overall agreement between computed spectra and experiment is very good and reveals different signatures for different conformers. This study shows that first-principles spectroscopic calculations of good accuracy are possible for dipeptides hence it opens possibilities for determination of dipeptide conformer structures by comparison of spectroscopic calculations with experiment.

Enzymatic Kinetic Isotope Effects from First-Principles Path Sampling Calculations.

PubMed

Varga, Matthew J; Schwartz, Steven D

2016-04-12

In this study, we develop and test a method to determine the rate of particle transfer and kinetic isotope effects in enzymatic reactions, specifically yeast alcohol dehydrogenase (YADH), from first-principles. Transition path sampling (TPS) and normal mode centroid dynamics (CMD) are used to simulate these enzymatic reactions without knowledge of their reaction coordinates and with the inclusion of quantum effects, such as zero-point energy and tunneling, on the transferring particle. Though previous studies have used TPS to calculate reaction rate constants in various model and real systems, it has not been applied to a system as large as YADH. The calculated primary H/D kinetic isotope effect agrees with previously reported experimental results, within experimental error. The kinetic isotope effects calculated with this method correspond to the kinetic isotope effect of the transfer event itself. The results reported here show that the kinetic isotope effects calculated from first-principles, purely for barrier passage, can be used to predict experimental kinetic isotope effects in enzymatic systems.

Toward the accurate first-principles prediction of ionization equilibria in proteins.

PubMed

Khandogin, Jana; Brooks, Charles L

2006-08-08

The calculation of pK(a) values for ionizable sites in proteins has been traditionally based on numerical solutions of the Poisson-Boltzmann equation carried out using a high-resolution protein structure. In this paper, we present a method based on continuous constant pH molecular dynamics (CPHMD) simulations, which allows the first-principles description of protein ionization equilibria. Our method utilizes an improved generalized Born implicit solvent model with an approximate Debye-Hückel screening function to account for salt effects and the replica-exchange (REX) protocol for enhanced conformational and protonation state sampling. The accuracy and robustness of the present method are demonstrated by 1 ns REX-CPHMD titration simulations of 10 proteins, which exhibit anomalously large pK(a) shifts for the carboxylate and histidine side chains. The experimental pK(a) values of these proteins are reliably reproduced with a root-mean-square error ranging from 0.6 unit for proteins containing few buried ionizable side chains to 1.0 unit or slightly higher for proteins containing ionizable side chains deeply buried in the core and experiencing strong charge-charge interactions. This unprecedented level of agreement with experimental benchmarks for the de novo calculation of pK(a) values suggests that the CPHMD method is maturing into a practical tool for the quantitative prediction of protein ionization equilibria, and this, in turn, opens a door to atomistic simulations of a wide variety of pH-coupled conformational phenomena in biological macromolecules such as protein folding or misfolding, aggregation, ligand binding, membrane interaction, and catalysis.

Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy

NASA Astrophysics Data System (ADS)

Cao, Binghua; Fan, Mengbao

2010-10-01

Terahertz wave is the electromagnetic spectrum situated between microwave and infrared wave. Quantitative analysis based on terahertz spectroscopy is very important for the application of terahertz techniques. But how to realize it is still under study. L-tartaric acid is widely used as acidulant in beverage, and other food, such as soft drinks, wine, candy, bread and some colloidal sweetmeats. In this paper, terahertz time-domain spectroscopy is applied to quantify the tartaric acid. Two methods are employed to process the terahertz spectra of different samples with different content of tartaric acid. The first one is linear regression combining correlation analysis. The second is partial least square (PLS), in which the absorption spectra in the 0.8-1.4THz region are used to quantify the tartaric acid. To compare the performance of these two principles, the relative error of the two methods is analyzed. For this experiment, the first method does better than the second one. But the first method is suitable for the quantitative analysis of materials which has obvious terahertz absorption peaks, while for material which has no obvious terahertz absorption peaks, the second one is more appropriate.

Roy's safety-first portfolio principle in financial risk management of disastrous events.

PubMed

Chiu, Mei Choi; Wong, Hoi Ying; Li, Duan

2012-11-01

Roy pioneers the concept and practice of risk management of disastrous events via his safety-first principle for portfolio selection. More specifically, his safety-first principle advocates an optimal portfolio strategy generated from minimizing the disaster probability, while subject to the budget constraint and the mean constraint that the expected final wealth is not less than a preselected disaster level. This article studies the dynamic safety-first principle in continuous time and its application in asset and liability management. We reveal that the distortion resulting from dropping the mean constraint, as a common practice to approximate the original Roy's setting, either leads to a trivial case or changes the problem nature completely to a target-reaching problem, which produces a highly leveraged trading strategy. Recognizing the ill-posed nature of the corresponding Lagrangian method when retaining the mean constraint, we invoke a wisdom observed from a limited funding-level regulation of pension funds and modify the original safety-first formulation accordingly by imposing an upper bound on the funding level. This model revision enables us to solve completely the safety-first asset-liability problem by a martingale approach and to derive an optimal policy that follows faithfully the spirit of the safety-first principle and demonstrates a prominent nature of fighting for the best and preventing disaster from happening. © 2012 Society for Risk Analysis.

A Case-Based Reasoning Method with Rank Aggregation

NASA Astrophysics Data System (ADS)

Sun, Jinhua; Du, Jiao; Hu, Jian

2018-03-01

In order to improve the accuracy of case-based reasoning (CBR), this paper addresses a new CBR framework with the basic principle of rank aggregation. First, the ranking methods are put forward in each attribute subspace of case. The ordering relation between cases on each attribute is got between cases. Then, a sorting matrix is got. Second, the similar case retrieval process from ranking matrix is transformed into a rank aggregation optimal problem, which uses the Kemeny optimal. On the basis, a rank aggregation case-based reasoning algorithm, named RA-CBR, is designed. The experiment result on UCI data sets shows that case retrieval accuracy of RA-CBR algorithm is higher than euclidean distance CBR and mahalanobis distance CBR testing.So we can get the conclusion that RA-CBR method can increase the performance and efficiency of CBR.

A new leakage measurement method for damaged seal material

NASA Astrophysics Data System (ADS)

Wang, Shen; Yao, Xue Feng; Yang, Heng; Yuan, Li; Dong, Yi Feng

2018-07-01

In this paper, a new leakage measurement method based on the temperature field and temperature gradient field is proposed for detecting the leakage location and measuring the leakage rate in damaged seal material. First, a heat transfer leakage model is established, which can calculate the leakage rate based on the temperature gradient field near the damaged zone. Second, a finite element model of an infinite plate with a damaged zone is built to calculate the leakage rate, which fits the simulated leakage rate well. Finally, specimens in a tubular rubber seal with different damage shapes are used to conduct the leakage experiment, validating the correctness of this new measurement principle for the leakage rate and the leakage position. The results indicate the feasibility of the leakage measurement method for damaged seal material based on the temperature gradient field from infrared thermography.

Exchange and spin-orbit induced phenomena in diluted (Ga,Mn)As from first principles

NASA Astrophysics Data System (ADS)

Kudrnovský, J.; Drchal, V.; Turek, I.

2016-08-01

Physical properties induced by exchange interactions (Curie temperature and spin stiffness) and spin-orbit coupling (anomalous Hall effect, anisotropic magnetoresistance, and Gilbert damping) in the diluted (Ga,Mn)As ferromagnetic semiconductor are studied from first principles. Recently developed Kubo-Bastin transport theory and nonlocal torque operator formulation of the Gilbert damping as formulated in the tight-binding linear muffin-tin orbital method are used. The first-principles Liechtenstein mapping is employed to construct an effective Heisenberg Hamiltonian and to estimate Curie temperature and spin stiffness in the real-space random-phase approximation. Good agreement of calculated physical quantities with experiments on well-annealed samples containing only a small amount of compensating defects is obtained.

Dynamic Fuzzy Model Development for a Drum-type Boiler-turbine Plant Through GK Clustering

NASA Astrophysics Data System (ADS)

Habbi, Ahcène; Zelmat, Mimoun

2008-10-01

This paper discusses a TS fuzzy model identification method for an industrial drum-type boiler plant using the GK fuzzy clustering approach. The fuzzy model is constructed from a set of input-output data that covers a wide operating range of the physical plant. The reference data is generated using a complex first-principle-based mathematical model that describes the key dynamical properties of the boiler-turbine dynamics. The proposed fuzzy model is derived by means of fuzzy clustering method with particular attention on structure flexibility and model interpretability issues. This may provide a basement of a new way to design model based control and diagnosis mechanisms for the complex nonlinear plant.

The many-body Wigner Monte Carlo method for time-dependent ab-initio quantum simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sellier, J.M., E-mail: jeanmichel.sellier@parallel.bas.bg; Dimov, I.

2014-09-15

The aim of ab-initio approaches is the simulation of many-body quantum systems from the first principles of quantum mechanics. These methods are traditionally based on the many-body Schrödinger equation which represents an incredible mathematical challenge. In this paper, we introduce the many-body Wigner Monte Carlo method in the context of distinguishable particles and in the absence of spin-dependent effects. Despite these restrictions, the method has several advantages. First of all, the Wigner formalism is intuitive, as it is based on the concept of a quasi-distribution function. Secondly, the Monte Carlo numerical approach allows scalability on parallel machines that is practicallymore » unachievable by means of other techniques based on finite difference or finite element methods. Finally, this method allows time-dependent ab-initio simulations of strongly correlated quantum systems. In order to validate our many-body Wigner Monte Carlo method, as a case study we simulate a relatively simple system consisting of two particles in several different situations. We first start from two non-interacting free Gaussian wave packets. We, then, proceed with the inclusion of an external potential barrier, and we conclude by simulating two entangled (i.e. correlated) particles. The results show how, in the case of negligible spin-dependent effects, the many-body Wigner Monte Carlo method provides an efficient and reliable tool to study the time-dependent evolution of quantum systems composed of distinguishable particles.« less

Design principles for elementary gene circuits: Elements, methods, and examples

NASA Astrophysics Data System (ADS)

Savageau, Michael A.

2001-03-01

The control of gene expression involves complex circuits that exhibit enormous variation in design. For years the most convenient explanation for these variations was historical accident. According to this view, evolution is a haphazard process in which many different designs are generated by chance; there are many ways to accomplish the same thing, and so no further meaning can be attached to such different but equivalent designs. In recent years a more satisfying explanation based on design principles has been found for at least certain aspects of gene circuitry. By design principle we mean a rule that characterizes some biological feature exhibited by a class of systems such that discovery of the rule allows one not only to understand known instances but also to predict new instances within the class. The central importance of gene regulation in modern molecular biology provides strong motivation to search for more of these underlying design principles. The search is in its infancy and there are undoubtedly many design principles that remain to be discovered. The focus of this three-part review will be the class of elementary gene circuits in bacteria. The first part reviews several elements of design that enter into the characterization of elementary gene circuits in prokaryotic organisms. Each of these elements exhibits a variety of realizations whose meaning is generally unclear. The second part reviews mathematical methods used to represent, analyze, and compare alternative designs. Emphasis is placed on particular methods that have been used successfully to identify design principles for elementary gene circuits. The third part reviews four design principles that make specific predictions regarding (1) two alternative modes of gene control, (2) three patterns of coupling gene expression in elementary circuits, (3) two types of switches in inducible gene circuits, and (4) the realizability of alternative gene circuits and their response to phased environmental cues. In each case, the predictions are supported by experimental evidence. These results are important for understanding the function, design, and evolution of elementary gene circuits.

Theory of atomic spectral emission intensity

NASA Astrophysics Data System (ADS)

Yngström, Sten

1994-07-01

The theoretical derivation of a new spectral line intensity formula for atomic radiative emission is presented. The theory is based on first principles of quantum physics, electrodynamics, and statistical physics. Quantum rules lead to revision of the conventional principle of local thermal equilibrium of matter and radiation. Study of electrodynamics suggests absence of spectral emission from fractions of the numbers of atoms and ions in a plasma due to radiative inhibition caused by electromagnetic force fields. Statistical probability methods are extended by the statement: A macroscopic physical system develops in the most probable of all conceivable ways consistent with the constraining conditions for the system. The crucial role of statistical physics in transforming quantum logic into common sense logic is stressed. The theory is strongly supported by experimental evidence.

Entanglement-Based Machine Learning on a Quantum Computer

NASA Astrophysics Data System (ADS)

Cai, X.-D.; Wu, D.; Su, Z.-E.; Chen, M.-C.; Wang, X.-L.; Li, Li; Liu, N.-L.; Lu, C.-Y.; Pan, J.-W.

2015-03-01

Machine learning, a branch of artificial intelligence, learns from previous experience to optimize performance, which is ubiquitous in various fields such as computer sciences, financial analysis, robotics, and bioinformatics. A challenge is that machine learning with the rapidly growing "big data" could become intractable for classical computers. Recently, quantum machine learning algorithms [Lloyd, Mohseni, and Rebentrost, arXiv.1307.0411] were proposed which could offer an exponential speedup over classical algorithms. Here, we report the first experimental entanglement-based classification of two-, four-, and eight-dimensional vectors to different clusters using a small-scale photonic quantum computer, which are then used to implement supervised and unsupervised machine learning. The results demonstrate the working principle of using quantum computers to manipulate and classify high-dimensional vectors, the core mathematical routine in machine learning. The method can, in principle, be scaled to larger numbers of qubits, and may provide a new route to accelerate machine learning.

Proof-of-principle Experiment of a Ferroelectric Tuner for the 1.3 GHz Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi,E.M.; Hahn, H.; Shchelkunov, S. V.

2009-01-01

A novel tuner has been developed by the Omega-P company to achieve fast control of the accelerator RF cavity frequency. The tuner is based on the ferroelectric property which has a variable dielectric constant as function of applied voltage. Tests using a Brookhaven National Laboratory (BNL) 1.3 GHz electron gun cavity have been carried out for a proof-of-principle experiment of the ferroelectric tuner. Two different methods were used to determine the frequency change achieved with the ferroelectric tuner (FT). The first method is based on a S11 measurement at the tuner port to find the reactive impedance change when themore » voltage is applied. The reactive impedance change then is used to estimate the cavity frequency shift. The second method is a direct S21 measurement of the frequency shift in the cavity with the tuner connected. The estimated frequency change from the reactive impedance measurement due to 5 kV is in the range between 3.2 kHz and 14 kHz, while 9 kHz is the result from the direct measurement. The two methods are in reasonable agreement. The detail description of the experiment and the analysis are discussed in the paper.« less

76 FR 49841 - Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-11

.... Each cost allocation method must satisfy six cost allocation principles. DATES: Effective Date: This... 86 c. Commission Determination 99 3. Regional Transmission Planning Principles........ 118 a.... Principles for Regional and Interregional Cost 585 Allocation 1. Use of a Principles-Based Approach 585 a...

Two-body potential model based on cosine series expansion for ionic materials

DOE PAGES

Oda, Takuji; Weber, William J.; Tanigawa, Hisashi

2015-09-23

There is a method to construct a two-body potential model for ionic materials with a Fourier series basis and we examine it. For this method, the coefficients of cosine basis functions are uniquely determined by solving simultaneous linear equations to minimize the sum of weighted mean square errors in energy, force and stress, where first-principles calculation results are used as the reference data. As a validation test of the method, potential models for magnesium oxide are constructed. The mean square errors appropriately converge with respect to the truncation of the cosine series. This result mathematically indicates that the constructed potentialmore » model is sufficiently close to the one that is achieved with the non-truncated Fourier series and demonstrates that this potential virtually provides minimum error from the reference data within the two-body representation. The constructed potential models work appropriately in both molecular statics and dynamics simulations, especially if a two-step correction to revise errors expected in the reference data is performed, and the models clearly outperform two existing Buckingham potential models that were tested. Moreover, the good agreement over a broad range of energies and forces with first-principles calculations should enable the prediction of materials behavior away from equilibrium conditions, such as a system under irradiation.« less

Removal of central obscuration and spider arm effects with beam-shaping coronagraphy

NASA Astrophysics Data System (ADS)

Abe, L.; Murakami, N.; Nishikawa, J.; Tamura, M.

2006-05-01

This paper describes a method for removing the effect of a centrally obscured aperture with additional spider arms in arbitrary geometrical configurations. The proposed method is based on a two-stage process where the light beam is first shaped to remove the central obscuration and spider arms, in order to feed a second, highly efficient coronagraph. The beam-shaping stage is a combination of a diffraction mask in the first focal plane and a complex amplitude filter located in the conjugate pupil. This paper specifically describes the case of using Lyot occulting masks and circular phase-shifting masks as diffracting components. The basic principle of the method is given along with an analytical description and numerical simulations. Substantial improvement in the performance of high-contrast coronagraphs can be obtained with this method, even if the beam-shaping filter is not perfectly manufactured.

First Principles of Attitudinal Change: A Review of Principles, Methods and Strategies

ERIC Educational Resources Information Center

Mueller, Chad; Lim, Jieun; Watson, Sunnie Lee

2017-01-01

Knowing how to effectively design attitudinal change instruction for various learning settings is essential for instructional designers. However, the research on instructional design for attitudinal change instruction has been relatively dispersed and lacks cohesion, despite its increasing importance. The purposes of this paper are to (1) reignite…

Empowerment Starts Here: Seven Principles to Empowering Urban Youth

ERIC Educational Resources Information Center

Dye, Angela

2011-01-01

"Empowerment Starts Here" covers an experimental approach to social change within urban communities by way of seven distinct principles for student empowerment. Turning classroom methods into a school model, Preparatory School for Global Leadership was the first to experience student empowerment at a school-wide level. This book provides insight…

Physical Principle for Generation of Randomness

NASA Technical Reports Server (NTRS)

Zak, Michail

2009-01-01

A physical principle (more precisely, a principle that incorporates mathematical models used in physics) has been conceived as the basis of a method of generating randomness in Monte Carlo simulations. The principle eliminates the need for conventional random-number generators. The Monte Carlo simulation method is among the most powerful computational methods for solving high-dimensional problems in physics, chemistry, economics, and information processing. The Monte Carlo simulation method is especially effective for solving problems in which computational complexity increases exponentially with dimensionality. The main advantage of the Monte Carlo simulation method over other methods is that the demand on computational resources becomes independent of dimensionality. As augmented by the present principle, the Monte Carlo simulation method becomes an even more powerful computational method that is especially useful for solving problems associated with dynamics of fluids, planning, scheduling, and combinatorial optimization. The present principle is based on coupling of dynamical equations with the corresponding Liouville equation. The randomness is generated by non-Lipschitz instability of dynamics triggered and controlled by feedback from the Liouville equation. (In non-Lipschitz dynamics, the derivatives of solutions of the dynamical equations are not required to be bounded.)

Practice-Based Evidence: Delivering What Works

ERIC Educational Resources Information Center

Brendtro, Larry K.; Mitchell, Martin L.

2012-01-01

Many methods claim to be Evidence-Based Practices. Yet success comes not from a particular practice, but principles that underlie all effective helping. This article uses the principle of consilience to tap knowledge from science, values, and practical experience.

Environmental optimal control strategies based on plant canopy photosynthesis responses and greenhouse climate model

NASA Astrophysics Data System (ADS)

Deng, Lujuan; Xie, Songhe; Cui, Jiantao; Liu, Tao

2006-11-01

It is the essential goal of intelligent greenhouse environment optimal control to enhance income of cropper and energy save. There were some characteristics such as uncertainty, imprecision, nonlinear, strong coupling, bigger inertia and different time scale in greenhouse environment control system. So greenhouse environment optimal control was not easy and especially model-based optimal control method was more difficult. So the optimal control problem of plant environment in intelligent greenhouse was researched. Hierarchical greenhouse environment control system was constructed. In the first level data measuring was carried out and executive machine was controlled. Optimal setting points of climate controlled variable in greenhouse was calculated and chosen in the second level. Market analysis and planning were completed in third level. The problem of the optimal setting point was discussed in this paper. Firstly the model of plant canopy photosynthesis responses and the model of greenhouse climate model were constructed. Afterwards according to experience of the planting expert, in daytime the optimal goals were decided according to the most maximal photosynthesis rate principle. In nighttime on plant better growth conditions the optimal goals were decided by energy saving principle. Whereafter environment optimal control setting points were computed by GA. Compared the optimal result and recording data in real system, the method is reasonable and can achieve energy saving and the maximal photosynthesis rate in intelligent greenhouse

First-Principles Calculations of Current-Induced Spin-Transfer Torques in Magnetic Domain Walls

NASA Astrophysics Data System (ADS)

Tang, Ling; Xu, Zhijun; Yang, Zejin

2013-05-01

Current-induced spin-transfer torques (STTs) have been studied in Fe, Co and Ni domain walls (DWs) by the method based on the first-principles noncollinear calculations of scattering wavefunctions expanded in the tight-binding linearized muffin-tin orbital (TB-LMTO) basis. The results show that the out-of-plane component of nonadiabatic STT in Fe DW has localized form, which is in contrast to the typical nonlocal oscillating nonadiabatic torques obtained in Co and Ni DWs. Meanwhile, the degree of nonadiabaticity in STT is also much greater for Fe DW. Further, our results demonstrate that compared to the well-known first-order nonadiabatic STT, the torque in the third-order spatial derivative of local spin can better describe the distribution of localized nonadiabatic STT in Fe DW. The dynamics of local spin driven by this third-order torques in Fe DW have been investigated by the Landau-Lifshitz-Gilbert (LLG) equation. The calculated results show that with the same amplitude of STTs the DW velocity induced by this third-order term is about half of the wall speed for the case of the first-order nonadiabatic STT.

3D Diffraction Microscope Provides a First Deep View

NASA Astrophysics Data System (ADS)

Miao, Jianwei

2005-03-01

When a coherent diffraction pattern is sampled at a spacing sufficiently finer than the Bragg peak frequency (i.e. the inverse of the sample size), the phase information is in principle encoded inside the diffraction pattern, and can be directly retrieved by using an iterative process. In combination of this oversampling phasing method with either coherent X-rays or electrons, a novel form of diffraction microscopy has recently been developed to image nanoscale materials and biological structures. In this talk, I will present the principle of the oversampling method, discuss the first experimental demonstration of this microscope, and illustrate some applications in nanoscience and biology.

First-principles calculations of 17O nuclear magnetic resonance chemical shielding in Pb(Zr(1/2)Ti(1/2))O3 and Pb(Mg(1/3)Nb(2/3))O3: linear dependence on transition-metal/oxygen bond lengths.

PubMed

Pechkis, Daniel L; Walter, Eric J; Krakauer, Henry

2011-09-21

First-principles density functional theory oxygen chemical shift tensors were calculated for A(B,B')O(3) perovskite alloys Pb(Zr(1/2)Ti(1/2))O(3) (PZT) and Pb(Mg(1/3)Nb(2/3))O(3) (PMN). Quantum chemistry methods for embedded clusters and the gauge including projector augmented waves (GIPAW) method [C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001)] for periodic boundary conditions were used. Results from both methods are in good agreement for PZT and prototypical perovskites. PMN results were obtained using only GIPAW. Both isotropic δ(iso) and axial δ(ax) chemical shifts were found to vary approximately linearly as a function of the nearest-distance transition-metal/oxygen bond length, r(s). Using these results, we argue against Ti clustering in PZT, as conjectured from recent (17)O NMR magic-angle-spinning measurements. Our findings indicate that (17)O NMR measurements, coupled with first-principles calculations, can be an important probe of local structure in complex perovskite solid solutions.

First-principles calculations of 17O nuclear magnetic resonance chemical shielding in Pb(Zr1/2Ti1/2)O3 and Pb(Mg1/3Nb2/3)O3: Linear dependence on transition-metal/oxygen bond lengths

NASA Astrophysics Data System (ADS)

Pechkis, Daniel L.; Walter, Eric J.; Krakauer, Henry

2011-09-01

First-principles density functional theory oxygen chemical shift tensors were calculated for A(B,B')O3 perovskite alloys Pb(Zr1/2Ti1/2)O3 (PZT) and Pb(Mg1/3Nb2/3)O3 (PMN). Quantum chemistry methods for embedded clusters and the gauge including projector augmented waves (GIPAW) method [C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001)], 10.1103/PhysRevB.63.245101 for periodic boundary conditions were used. Results from both methods are in good agreement for PZT and prototypical perovskites. PMN results were obtained using only GIPAW. Both isotropic δiso and axial δax chemical shifts were found to vary approximately linearly as a function of the nearest-distance transition-metal/oxygen bond length, rs. Using these results, we argue against Ti clustering in PZT, as conjectured from recent 17O NMR magic-angle-spinning measurements. Our findings indicate that 17O NMR measurements, coupled with first-principles calculations, can be an important probe of local structure in complex perovskite solid solutions.

Valuing lives and allocating resources: a defense of the modified youngest first principle of scarce resource distribution.

PubMed

Tallman, Ruth

2014-06-01

In this paper, I argue that the 'modified youngest first' principle provides a morally appropriate criterion for making decisions regarding the distribution of scarce medical resources, and that it is morally preferable to the simple 'youngest first' principle. Based on the complete lives system's goal of maximizing complete lives rather than individual life episodes, I argue that essential to the value we see in complete lives is the first person value attributed by the experiencer of that life. For a life to be 'complete' or 'incomplete,' the subject of that life must be able to understand the concept of a complete life, to have started goals and projects, and to know what it would be for that life to be complete. As the very young are not able to do this, it can reasonably be said that their characteristically human lives have not yet begun, giving those accepting a complete lives approach good reason to accept the modified youngest first principle over a simple 'youngest first' approach. © 2012 John Wiley & Sons Ltd.

Advanced first-principles theory of superconductivity including both lattice vibrations and spin fluctuations: The case of FeB4

NASA Astrophysics Data System (ADS)

Bekaert, J.; Aperis, A.; Partoens, B.; Oppeneer, P. M.; Milošević, M. V.

2018-01-01

We present an advanced method to study spin fluctuations in superconductors quantitatively and entirely from first principles. This method can be generally applied to materials where electron-phonon coupling and spin fluctuations coexist. We employ it here to examine the recently synthesized superconductor iron tetraboride (FeB4) with experimental Tc˜2.4 K [H. Gou et al., Phys. Rev. Lett. 111, 157002 (2013), 10.1103/PhysRevLett.111.157002]. We prove that FeB4 is particularly prone to ferromagnetic spin fluctuations due to the presence of iron, resulting in a large Stoner interaction strength, I =1.5 eV, as calculated from first principles. The other important factor is its Fermi surface that consists of three separate sheets, among which two are nested ellipsoids. The resulting susceptibility has a ferromagnetic peak around q =0 , from which we calculated the repulsive interaction between Cooper pair electrons using the random phase approximation. Subsequently, we combined the electron-phonon interaction calculated from first principles with the spin fluctuation interaction in fully anisotropic Eliashberg theory calculations. We show that the resulting superconducting gap spectrum is conventional, yet very strongly depleted due to coupling to the spin fluctuations. The critical temperature decreases from Tc=41 K, if they are not taken into account, to Tc=1.7 K, in good agreement with the experimental value.

Principle-based concept analysis: Caring in nursing education

PubMed Central

Salehian, Maryam; Heydari, Abbas; Aghebati, Nahid; Moonaghi, Hossein Karimi; Mazloom, Seyed Reza

2016-01-01

Introduction The aim of this principle-based concept analysis was to analyze caring in nursing education and to explain the current state of the science based on epistemologic, pragmatic, linguistic, and logical philosophical principles. Methods A principle-based concept analysis method was used to analyze the nursing literature. The dataset included 46 English language studies, published from 2005 to 2014, and they were retrieved through PROQUEST, MEDLINE, CINAHL, ERIC, SCOPUS, and SID scientific databases. The key dimensions of the data were collected using a validated data-extraction sheet. The four principles of assessing pragmatic utility were used to analyze the data. The data were managed by using MAXQDA 10 software. Results The scientific literature that deals with caring in nursing education relies on implied meaning. Caring in nursing education refers to student-teacher interactions that are formed on the basis of human values and focused on the unique needs of the students (epistemological principle). The result of student-teacher interactions is the development of both the students and the teachers. Numerous applications of the concept of caring in nursing education are available in the literature (pragmatic principle). There is consistency in the meaning of the concept, as a central value of the faculty-student interaction (linguistic principle). Compared with other related concepts, such as “caring pedagogy,” “value-based education,” and “teaching excellence,” caring in nursing education does not have exact and clear conceptual boundaries (logic principle). Conclusion Caring in nursing education was identified as an approach to teaching and learning, and it is formed based on teacher-student interactions and sustainable human values. A greater understanding of the conceptual basis of caring in nursing education will improve the caring behaviors of teachers, create teaching-learning environments, and help experts in curriculum development. PMID:27123225

Electromagnetic diagnostic techniques for hypervelocity projectile detection, velocity measurement, and size characterization: Theoretical concept and first experimental test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uhlig, W. Casey; Heine, Andreas, E-mail: andreas.heine@emi.fraunhofer.de

2015-11-14

A new measurement technique is suggested to augment the characterization and understanding of hypervelocity projectiles before impact. The electromagnetic technique utilizes magnetic diffusion principles to detect particles, measure velocity, and indicate relative particle dimensions. It is particularly suited for detection of small particles that may be difficult to track utilizing current characterization methods, such as high-speed video or flash radiography but can be readily used for large particle detection, where particle spacing or location is not practical for other measurement systems. In this work, particles down to 2 mm in diameter have been characterized while focusing on confining the detection signalmore » to enable multi-particle characterization with limited particle-to-particle spacing. The focus of the paper is on the theoretical concept and the analysis of its applicability based on analytical and numerical calculation. First proof-of-principle experimental tests serve to further validate the method. Some potential applications are the characterization of particles from a shaped-charge jet after its break-up and investigating debris in impact experiments to test theoretical models for the distribution of particles size, number, and velocity.« less

First principles calculation of current-induced forces in atomic gold contacts

NASA Astrophysics Data System (ADS)

Brandbyge, Mads; Stokbro, Kurt; Taylor, Jeremy; Mozos, Jose-Luis; Ordejon, Pablo

2002-03-01

We have recently developed an first principles method [1] for calculating the electronic structure, electronic transport, and forces acting on the atoms, for atomic scale systems connected to semi-infinite electrodes and with an applied voltage bias. Our method is based on the density functional theory (DFT) as implemented in the well tested SIESTA program [2]. We fully deal with the atomistic structure of the whole system, treating both the contact and the electrodes on the same footing. The effect of the finite bias (including selfconsistency and the solution of the electrostatic problem) is taken into account using nonequilibrium Green's functions. In this talk we show results for the forces acting on the contact atoms due to the nonequilibrium situation in the electronic subsystem, i.e. in the presence of an electronic current. We concentrate on one atom wide gold contacts/wires connected to bulk gold electrodes. References [1] Our implementation is called TranSIESTA and is described in M. Brandbyge, J. Taylor, K. Stokbro, J-L. Mozos, and P. Ordejon, cond-mat/0110650 [2] D. Sanchez-Portal, P. Ordejon, E. Artacho and J. Soler, Int. J. Quantum Chem. 65, 453 (1997).

Pioneering topological methods for network-based drug-target prediction by exploiting a brain-network self-organization theory.

PubMed

Durán, Claudio; Daminelli, Simone; Thomas, Josephine M; Haupt, V Joachim; Schroeder, Michael; Cannistraci, Carlo Vittorio

2017-04-26

The bipartite network representation of the drug-target interactions (DTIs) in a biosystem enhances understanding of the drugs' multifaceted action modes, suggests therapeutic switching for approved drugs and unveils possible side effects. As experimental testing of DTIs is costly and time-consuming, computational predictors are of great aid. Here, for the first time, state-of-the-art DTI supervised predictors custom-made in network biology were compared-using standard and innovative validation frameworks-with unsupervised pure topological-based models designed for general-purpose link prediction in bipartite networks. Surprisingly, our results show that the bipartite topology alone, if adequately exploited by means of the recently proposed local-community-paradigm (LCP) theory-initially detected in brain-network topological self-organization and afterwards generalized to any complex network-is able to suggest highly reliable predictions, with comparable performance with the state-of-the-art-supervised methods that exploit additional (non-topological, for instance biochemical) DTI knowledge. Furthermore, a detailed analysis of the novel predictions revealed that each class of methods prioritizes distinct true interactions; hence, combining methodologies based on diverse principles represents a promising strategy to improve drug-target discovery. To conclude, this study promotes the power of bio-inspired computing, demonstrating that simple unsupervised rules inspired by principles of topological self-organization and adaptiveness arising during learning in living intelligent systems (like the brain) can efficiently equal perform complicated algorithms based on advanced, supervised and knowledge-based engineering. © The Author 2017. Published by Oxford University Press.

Rule Extraction Based on Extreme Learning Machine and an Improved Ant-Miner Algorithm for Transient Stability Assessment.

PubMed

Li, Yang; Li, Guoqing; Wang, Zhenhao

2015-01-01

In order to overcome the problems of poor understandability of the pattern recognition-based transient stability assessment (PRTSA) methods, a new rule extraction method based on extreme learning machine (ELM) and an improved Ant-miner (IAM) algorithm is presented in this paper. First, the basic principles of ELM and Ant-miner algorithm are respectively introduced. Then, based on the selected optimal feature subset, an example sample set is generated by the trained ELM-based PRTSA model. And finally, a set of classification rules are obtained by IAM algorithm to replace the original ELM network. The novelty of this proposal is that transient stability rules are extracted from an example sample set generated by the trained ELM-based transient stability assessment model by using IAM algorithm. The effectiveness of the proposed method is shown by the application results on the New England 39-bus power system and a practical power system--the southern power system of Hebei province.

SIEST-A-RT: a study of vacancy diffusion in crystalline silicon using a local-basis first-principle (SIESTA) activation technique (ART).

NASA Astrophysics Data System (ADS)

El Mellouhi, Fedwa; Mousseau, Normand; Ordejón, Pablo

2003-03-01

We report on a first-principle study of vacancy-induced self-diffusion in crystalline silicon. Our simulations are performed on supercells containing 63 and 215 atoms. We generate the diffusion paths using the activation-relaxation technique (ART) [1], which can sample efficiently the energy landscape of complex systems. The forces and energy are evaluated using SIESTA [2], a selfconsistent density functional method using standard norm-conserving pseudopotentials and a flexible numerical linear combination of atomic orbitals basis set. Combining these two methods allows us to identify diffusion paths that would not be reachable with this degree of accuracy, using other methods. After a full relaxation of the neutral vacancy, we proceed to search for local diffusion paths. We identify various mechanisms like the formation of the four fold coordinated defect, and the recombination of dangling bonds by WWW process. The diffusion of the vacancy proceeds by hops to first nearest neighbor with an energy barrier of 0.69 eV. This work is funded in part by NSERC and NATEQ. NM is a Cottrell Scholar of the Research Corporation. [1] G. T. Barkema and N. Mousseau, Event-based relaxation of continuous disordered systems, Phys. Rev. Lett. 77, 4358 (1996); N. Mousseau and G. T. Barkema, Traveling through potential energy landscapes of disordered materials: ART, Phys. Rev. E 57, 2419 (1998). [2] Density functional method for very large systems with LCAO basis sets D. Sánchez-Portal, P. Ordejón, E. Artacho and J. M. Soler, Int. J. Quant. Chem. 65, 453 (1997).

First Principles Optical Absorption Spectra of Organic Molecules Adsorbed on Titania Nanoparticles

NASA Astrophysics Data System (ADS)

Baishya, Kopinjol; Ogut, Serdar; Mete, Ersen; Gulseren, Oguz; Ellialtioglu, Sinasi

2012-02-01

We present results from first principles computations on passivated rutile TiO2 nanoparticles in both free-standing and dye-sensitized configurations to investigate the size dependence of their optical absorption spectra. The computations are performed using time-dependent density functional theory (TDDFT) as well as GW-Bethe-Salpeter-Equation (GWBSE) methods and compared with each other. We interpret the first principles spectra for free-standing TiO2 nanoparticles within the framework of the classical Mie-Gans theory using the bulk dielectric function of TiO2. We investigate the effects of the titania support on the absorption spectra of a particular set of perylene-diimide (PDI) derived dye molecules, namely brominated PDI (Br2C24H8N2O4) and its glycine and aspartine derivatives.

Lattice Anharmonicity and Thermal Conductivity from Compressive Sensing of First-Principles Calculations

DOE PAGES

Zhou, Fei; Nielson, Weston; Xia, Yi; ...

2014-10-27

First-principles prediction of lattice thermal conductivity K L of strongly anharmonic crystals is a long-standing challenge in solid state physics. Using recent advances in information science, we propose a systematic and rigorous approach to this problem, compressive sensing lattice dynamics (CSLD). Compressive sensing is used to select the physically important terms in the lattice dynamics model and determine their values in one shot. Non-intuitively, high accuracy is achieved when the model is trained on first-principles forces in quasi-random atomic configurations. The method is demonstrated for Si, NaCl, and Cu 12Sb 4S 13, an earth-abundant thermoelectric with strong phononphonon interactions thatmore » limit the room-temperature K L to values near the amorphous limit.« less

Uranium phase diagram from first principles

NASA Astrophysics Data System (ADS)

Yanilkin, Alexey; Kruglov, Ivan; Migdal, Kirill; Oganov, Artem; Pokatashkin, Pavel; Sergeev, Oleg

2017-06-01

The work is devoted to the investigation of uranium phase diagram up to pressure of 1 TPa and temperature of 15 kK based on density functional theory. First of all the comparison of pseudopotential and full potential calculations is carried out for different uranium phases. In the second step, phase diagram at zero temperature is investigated by means of program USPEX and pseudopotential calculations. Stable and metastable structures with close energies are selected. In order to obtain phase diagram at finite temperatures the preliminary selection of stable phases is made by free energy calculation based on small displacement method. For remaining candidates the accurate values of free energy are obtained by means of thermodynamic integration method (TIM). For this purpose quantum molecular dynamics are carried out at different volumes and temperatures. Interatomic potentials based machine learning are developed in order to consider large systems and long times for TIM. The potentials reproduce the free energy with the accuracy 1-5 meV/atom, which is sufficient for prediction of phase transitions. The equilibrium curves of different phases are obtained based on free energies. Melting curve is calculated by modified Z-method with developed potential.

A Review of Interface Electronic Systems for AT-cut Quartz Crystal Microbalance Applications in Liquids

PubMed Central

Arnau, Antonio

2008-01-01

From the first applications of AT-cut quartz crystals as sensors in solutions more than 20 years ago, the so-called quartz crystal microbalance (QCM) sensor is becoming into a good alternative analytical method in a great deal of applications such as biosensors, analysis of biomolecular interactions, study of bacterial adhesion at specific interfaces, pathogen and microorganism detection, study of polymer film-biomolecule or cell-substrate interactions, immunosensors and an extensive use in fluids and polymer characterization and electrochemical applications among others. The appropriate evaluation of this analytical method requires recognizing the different steps involved and to be conscious of their importance and limitations. The first step involved in a QCM system is the accurate and appropriate characterization of the sensor in relation to the specific application. The use of the piezoelectric sensor in contact with solutions strongly affects its behavior and appropriate electronic interfaces must be used for an adequate sensor characterization. Systems based on different principles and techniques have been implemented during the last 25 years. The interface selection for the specific application is important and its limitations must be known to be conscious of its suitability, and for avoiding the possible error propagation in the interpretation of results. This article presents a comprehensive overview of the different techniques used for AT-cut quartz crystal microbalance in in-solution applications, which are based on the following principles: network or impedance analyzers, decay methods, oscillators and lock-in techniques. The electronic interfaces based on oscillators and phase-locked techniques are treated in detail, with the description of different configurations, since these techniques are the most used in applications for detection of analytes in solutions, and in those where a fast sensor response is necessary. PMID:27879713

A first principles study on newly proposed (Ca/Sr/Ba)Fe2Bi2 compounds with their parent compounds

NASA Astrophysics Data System (ADS)

Sundareswari, M.; Jayalakshmi, D. S.; Viswanathan, E.

2016-02-01

The structural, electronic, bonding and magnetic properties of newly proposed iron-based compounds viz., CaFe2Bi2, SrFe2Bi2, BaFe2Bi2 with their Fermi surface topology are reported here for the first time by means of first principles calculation. All these properties of newly proposed compounds are compared and analysed along with their respective parent compounds namely (Ca,Sr,Ba)Fe2As2.

First-principles calculations of electronic, magnetic and optical properties of HoN doped with TM (Ti, V, Cr, Mn, Co and Ni)

NASA Astrophysics Data System (ADS)

Rouchdi, M.; Salmani, E.; Dehmani, M.; Ez-Zahraouy, H.; Hassanain, N.; Benyoussef, A.; Mzerd, A.

2018-02-01

Using the first-principles calculations within the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA), the structural, optical and magnetic properties of rare-earth nitride Ho0.95TM0.05N doped with transition metal (TM) atoms (Ti, V, Cr, Mn, Co and Ni) are investigated as a function the generalized gradient approximation and self-interaction correction (GGA-SIC) approximation. The optical properties are studied in detail by using ab-initio calculations. Using GGA-SIC we have showed that the bandgap value is in good agreement with the experimental value. Using GGA-SIC approximation for HoN, we have obtained a bandgap of 0.9 eV. Some of the dilute magnetic semiconductors (DMS) like Ho0.95TM0.05N under study exhibit a half-metallic behavior, which makes them suitable for spintronic applications. Moreover, the optical absorption spectra confirm the ferromagnetic stability based on the charge state of magnetic impurities.

First Principles Electronic Structure of Mn doped GaAs, GaP, and GaN Semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schulthess, Thomas C; Temmerman, Walter M; Szotek, Zdzislawa

We present first-principles electronic structure calculations of Mn doped III-V semiconductors based on the local spin-density approximation (LSDA) as well as the self-interaction corrected local spin density method (SIC-LSD). We find that it is crucial to use a self-interaction free approach to properly describe the electronic ground state. The SIC-LSD calculations predict the proper electronic ground state configuration for Mn in GaAs, GaP, and GaN. Excellent quantitative agreement with experiment is found for magnetic moment and p-d exchange in (GaMn)As. These results allow us to validate commonly used models for magnetic semiconductors. Furthermore, we discuss the delicate problem of extractingmore » binding energies of localized levels from density functional theory calculations. We propose three approaches to take into account final state effects to estimate the binding energies of the Mn-d levels in GaAs. We find good agreement between computed values and estimates from photoemisison experiments.« less

Spin polarization properties of benzene/graphene with transition metals as dopants: First principles calculations

NASA Astrophysics Data System (ADS)

Yuan, X. B.; Tian, Y. L.; Zhao, X. W.; Yue, W. W.; Hu, G. C.; Ren, J. F.

2018-05-01

First principles calculations are used to study the spin polarization properties of benzene molecule adsorbed on the graphene surface which doped with transition metals including Mn, Cr, Fe, Co, and Ni. The densities of states (DOS) of the benzene molecule can be induced to be spin split at the Fermi level only when it is adsorbed on Mn-, and Cr-doped graphene. The p-orbital of the benzene molecule will interact with the d orbital of the doped atoms, which will generate new spin coupling states and lead to obvious spin polarization of the benzene molecule. The spin-polarized density distributions as well as the differential charge density distributions of the systems also suggest that Mn-doped graphene will induce bigger spin polarization than that of Cr-doped graphene. Benzene molecule could be spin-polarized when it is adsorbed on the graphene surface with transition metal dopants, which could be a new method for researching graphene-based organic spintronic devices.

Glass Formation, Phase Equilibria, and Thermodynamic Assessment of the Al-Ce-Co System Assisted by First-Principles Energy Calculations

NASA Astrophysics Data System (ADS)

Gao, Michael C.; Ünlü, Necip; Mihalkovic, Marek; Widom, Michael; Shiflet, G. J.

2007-10-01

This study investigates glass formation, phase equilibria, and thermodynamic descriptions of the Al-rich Al-Ce-Co ternary system using a novel approach that combines critical experiments, CALPHAD modeling, and first-principles (FP) calculations. The glass formation range (GFR) and a partial 500 °C isotherm are determined using a range of experimental techniques including melt spinning, transmission electron microscopy (TEM), electron probe microanalysis (EPMA), X-ray diffraction, and differential thermal analysis (DTA). Three stable ternary phases are confirmed, namely, Al8CeCo2, Al4CeCo, and AlCeCo, while a metastable phase, Al5CeCo2, was discovered. The equilibrium and metastable phases identified by the present and earlier reported experiments, together with many hypothetical ternary compounds, are further studied by FP calculations. Based on new experimental data and FP calculations, the thermodynamics of the Al-rich Al-Co-Ce system is optimized using the CALPHAD method. Application to glass formation is discussed in light of present studies.

Biomimetic design processes in architecture: morphogenetic and evolutionary computational design.

PubMed

Menges, Achim

2012-03-01

Design computation has profound impact on architectural design methods. This paper explains how computational design enables the development of biomimetic design processes specific to architecture, and how they need to be significantly different from established biomimetic processes in engineering disciplines. The paper first explains the fundamental difference between computer-aided and computational design in architecture, as the understanding of this distinction is of critical importance for the research presented. Thereafter, the conceptual relation and possible transfer of principles from natural morphogenesis to design computation are introduced and the related developments of generative, feature-based, constraint-based, process-based and feedback-based computational design methods are presented. This morphogenetic design research is then related to exploratory evolutionary computation, followed by the presentation of two case studies focusing on the exemplary development of spatial envelope morphologies and urban block morphologies.

Multiscale study of metal nanoparticles

NASA Astrophysics Data System (ADS)

Lee, Byeongchan

Extremely small structures with reduced dimensionality have emerged as a scientific motif for their interesting properties. In particular, metal nanoparticles have been identified as a fundamental material in many catalytic activities; as a consequence, a better understanding of structure-function relationship of nanoparticles has become crucial. The functional analysis of nanoparticles, reactivity for example, requires an accurate method at the electronic structure level, whereas the structural analysis to find energetically stable local minima is beyond the scope of quantum mechanical methods as the computational cost becomes prohibitingly high. The challenge is that the inherent length scale and accuracy associated with any single method hardly covers the broad scale range spanned by both structural and functional analyses. In order to address this, and effectively explore the energetics and reactivity of metal nanoparticles, a hierarchical multiscale modeling is developed, where methodologies of different length scales, i.e. first principles density functional theory, atomistic calculations, and continuum modeling, are utilized in a sequential fashion. This work has focused on identifying the essential information that bridges two different methods so that a successive use of different methods is seamless. The bond characteristics of low coordination systems have been obtained with first principles calculations, and incorporated into the atomistic simulation. This also rectifies the deficiency of conventional interatomic potentials fitted to bulk properties, and improves the accuracy of atomistic calculations for nanoparticles. For the systematic shape selection of nanoparticles, we have improved the Wulff-type construction using a semi-continuum approach, in which atomistic surface energetics and crystallinity of materials are added on to the continuum framework. The developed multiscale modeling scheme is applied to the rational design of platinum nanoparticles in the range of 2.4 nm to 3.1 nm: energetically favorable structures have been determined in terms of semi-continuum binding energy, and the reactivity of the selected nanoparticle has been investigated based on local density of states from first principles calculations. The calculation suggests that the reactivity landscape of particles is more complex than the simple reactivity of clean surfaces, and the reactivity towards a particular reactant can be predicted for a given structure.

Fostering Formal Commutativity Knowledge with Approximate Arithmetic

PubMed Central

Hansen, Sonja Maria; Haider, Hilde; Eichler, Alexandra; Godau, Claudia; Frensch, Peter A.; Gaschler, Robert

2015-01-01

How can we enhance the understanding of abstract mathematical principles in elementary school? Different studies found out that nonsymbolic estimation could foster subsequent exact number processing and simple arithmetic. Taking the commutativity principle as a test case, we investigated if the approximate calculation of symbolic commutative quantities can also alter the access to procedural and conceptual knowledge of a more abstract arithmetic principle. Experiment 1 tested first graders who had not been instructed about commutativity in school yet. Approximate calculation with symbolic quantities positively influenced the use of commutativity-based shortcuts in formal arithmetic. We replicated this finding with older first graders (Experiment 2) and third graders (Experiment 3). Despite the positive effect of approximation on the spontaneous application of commutativity-based shortcuts in arithmetic problems, we found no comparable impact on the application of conceptual knowledge of the commutativity principle. Overall, our results show that the usage of a specific arithmetic principle can benefit from approximation. However, the findings also suggest that the correct use of certain procedures does not always imply conceptual understanding. Rather, the conceptual understanding of commutativity seems to lag behind procedural proficiency during elementary school. PMID:26560311

A flexible new method for 3D measurement based on multi-view image sequences

NASA Astrophysics Data System (ADS)

Cui, Haihua; Zhao, Zhimin; Cheng, Xiaosheng; Guo, Changye; Jia, Huayu

2016-11-01

Three-dimensional measurement is the base part for reverse engineering. The paper developed a new flexible and fast optical measurement method based on multi-view geometry theory. At first, feature points are detected and matched with improved SIFT algorithm. The Hellinger Kernel is used to estimate the histogram distance instead of traditional Euclidean distance, which is immunity to the weak texture image; then a new filter three-principle for filtering the calculation of essential matrix is designed, the essential matrix is calculated using the improved a Contrario Ransac filter method. One view point cloud is constructed accurately with two view images; after this, the overlapped features are used to eliminate the accumulated errors caused by added view images, which improved the camera's position precision. At last, the method is verified with the application of dental restoration CAD/CAM, experiment results show that the proposed method is fast, accurate and flexible for tooth 3D measurement.

Single underwater image enhancement based on color cast removal and visibility restoration

NASA Astrophysics Data System (ADS)

Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

2016-05-01

Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

Methods of Organizational Information Security

NASA Astrophysics Data System (ADS)

Martins, José; Dos Santos, Henrique

The principle objective of this article is to present a literature review for the methods used in the security of information at the level of organizations. Some of the principle problems are identified and a first group of relevant dimensions is presented for an efficient management of information security. The study is based on the literature review made, using some of the more relevant certified articles of this theme, in international reports and in the principle norms of management of information security. From the readings that were done, we identified some of the methods oriented for risk management, norms of certification and good practice of security of information. Some of the norms are oriented for the certification of the product or system and others oriented to the processes of the business. There are also studies with the proposal of Frameworks that suggest the integration of different approaches with the foundation of norms focused on technologies, in processes and taking into consideration the organizational and human environment of the organizations. In our perspective, the biggest contribute to the security of information is the development of a method of security of information for an organization in a conflicting environment. This should make available the security of information, against the possible dimensions of attack that the threats could exploit, through the vulnerability of the organizational actives. This method should support the new concepts of "Network centric warfare", "Information superiority" and "Information warfare" especially developed in this last decade, where information is seen simultaneously as a weapon and as a target.

Insight from first principles into the stability and magnetism of alkali-metal superoxide nanoclusters

NASA Astrophysics Data System (ADS)

Arcelus, Oier; Suaud, Nicolas; Katcho, Nebil A.; Carrasco, Javier

2017-05-01

Alkali-metal superoxides are gaining increasing interest as 2p magnetic materials for information and energy storage. Despite significant research efforts on bulk materials, gaps in our knowledge of the electronic and magnetic properties at the nanoscale still remain. Here, we focused on the role that structural details play in determining stability, electronic structure, and magnetic couplings of (MO2)n (M = Li, Na, and K, with n = 2-8) clusters. Using first-principles density functional theory based on the Perdew-Burke-Ernzerhof and Heyd-Scuseria-Ernzerhof functionals, we examined the effect of atomic structure on the relative stability of different polymorphs within each investigated cluster size. We found that small clusters prefer to form planar-ring structures, whereas non-planar geometries become more stable when increasing the cluster size. However, the crossover point depends on the nature of the alkali metal. Our analysis revealed that electrostatic interactions govern the highly ionic M-O2 bonding and ultimately control the relative stability between 2-D and 3-D geometries. In addition, we analyzed the weak magnetic couplings between superoxide molecules in (NaO2)4 clusters comparing model Hamiltonian methods based on Wannier function projections onto πg states with wave function-based multi-reference calculations.

Foundations of Quantum Mechanics: Derivation of a dissipative Schrödinger equation from first principles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonçalves, L.A.; Olavo, L.S.F., E-mail: olavolsf@gmail.com

Dissipation in Quantum Mechanics took some time to become a robust field of investigation after the birth of the field. The main issue hindering developments in the field is that the Quantization process was always tightly connected to the Hamiltonian formulation of Classical Mechanics. In this paper we present a quantization process that does not depend upon the Hamiltonian formulation of Classical Mechanics (although still departs from Classical Mechanics) and thus overcome the problem of finding, from first principles, a completely general Schrödinger equation encompassing dissipation. This generalized process of quantization is shown to be nothing but an extension ofmore » a more restricted version that is shown to produce the Schrödinger equation for Hamiltonian systems from first principles (even for Hamiltonian velocity dependent potential). - Highlights: • A Quantization process independent of the Hamiltonian formulation of quantum Mechanics is proposed. • This quantization method is applied to dissipative or absorptive systems. • A Dissipative Schrödinger equation is derived from first principles.« less

Materials Databases Infrastructure Constructed by First Principles Calculations: A Review

DOE PAGES

Lin, Lianshan

2015-10-13

The First Principles calculations, especially the calculation based on High-Throughput Density Functional Theory, have been widely accepted as the major tools in atom scale materials design. The emerging super computers, along with the powerful First Principles calculations, have accumulated hundreds of thousands of crystal and compound records. The exponential growing of computational materials information urges the development of the materials databases, which not only provide unlimited storage for the daily increasing data, but still keep the efficiency in data storage, management, query, presentation and manipulation. This review covers the most cutting edge materials databases in materials design, and their hotmore » applications such as in fuel cells. By comparing the advantages and drawbacks of these high-throughput First Principles materials databases, the optimized computational framework can be identified to fit the needs of fuel cell applications. The further development of high-throughput DFT materials database, which in essence accelerates the materials innovation, is discussed in the summary as well.« less

Science and technology convergence: with emphasis for nanotechnology-inspired convergence

NASA Astrophysics Data System (ADS)

Bainbridge, William S.; Roco, Mihail C.

2016-07-01

Convergence offers a new universe of discovery, innovation, and application opportunities through specific theories, principles, and methods to be implemented in research, education, production, and other societal activities. Using a holistic approach with shared goals, convergence seeks to transcend existing human limitations to achieve improved conditions for work, learning, aging, physical, and cognitive wellness. This paper outlines ten key theories that offer complementary perspectives on this complex dynamic. Principles and methods are proposed to facilitate and enhance science and technology convergence. Several convergence success stories in the first part of the 21st century—including nanotechnology and other emerging technologies—are discussed in parallel with case studies focused on the future. The formulation of relevant theories, principles, and methods aims at establishing the convergence science.

The microwave-assisted ionic-liquid method: a promising methodology in nanomaterials.

PubMed

Ma, Ming-Guo; Zhu, Jie-Fang; Zhu, Ying-Jie; Sun, Run-Cang

2014-09-01

In recent years, the microwave-assisted ionic-liquid method has been accepted as a promising methodology for the preparation of nanomaterials and cellulose-based nanocomposites. Applications of this method in the preparation of cellulose-based nanocomposites comply with the major principles of green chemistry, that is, they use an environmentally friendly method in environmentally preferable solvents to make use of renewable materials. This minireview focuses on the recent development of the synthesis of nanomaterials and cellulose-based nanocomposites by means of the microwave-assisted ionic-liquid method. We first discuss the preparation of nanomaterials including noble metals, metal oxides, complex metal oxides, metal sulfides, and other nanomaterials by means of this method. Then we provide an overview of the synthesis of cellulose-based nanocomposites by using this method. The emphasis is on the synthesis, microstructure, and properties of nanostructured materials obtained through this methodology. Our recent research on nanomaterials and cellulose-based nanocomposites by this rapid method is summarized. In addition, the formation mechanisms involved in the microwave-assisted ionic-liquid synthesis of nanostructured materials are discussed briefly. Finally, the future perspectives of this methodology in the synthesis of nanostructured materials are proposed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated and Contextual Basic Science Instruction in Preclinical Education: Problem-Based Learning Experience Enriched with Brain/Mind Learning Principles

ERIC Educational Resources Information Center

Gülpinar, Mehmet Ali; Isoglu-Alkaç, Ümmühan; Yegen, Berrak Çaglayan

2015-01-01

Recently, integrated and contextual learning models such as problem-based learning (PBL) and brain/mind learning (BML) have become prominent. The present study aimed to develop and evaluate a PBL program enriched with BML principles. In this study, participants were 295 first-year medical students. The study used both quantitative and qualitative…

DATA-CONSTRAINED CORONAL MASS EJECTIONS IN A GLOBAL MAGNETOHYDRODYNAMICS MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, M.; Manchester, W. B.; Van der Holst, B.

We present a first-principles-based coronal mass ejection (CME) model suitable for both scientific and operational purposes by combining a global magnetohydrodynamics (MHD) solar wind model with a flux-rope-driven CME model. Realistic CME events are simulated self-consistently with high fidelity and forecasting capability by constraining initial flux rope parameters with observational data from GONG, SOHO /LASCO, and STEREO /COR. We automate this process so that minimum manual intervention is required in specifying the CME initial state. With the newly developed data-driven Eruptive Event Generator using Gibson–Low configuration, we present a method to derive Gibson–Low flux rope parameters through a handful ofmore » observational quantities so that the modeled CMEs can propagate with the desired CME speeds near the Sun. A test result with CMEs launched with different Carrington rotation magnetograms is shown. Our study shows a promising result for using the first-principles-based MHD global model as a forecasting tool, which is capable of predicting the CME direction of propagation, arrival time, and ICME magnetic field at 1 au (see the companion paper by Jin et al. 2016a).« less

The estimation of bone cyst volume using the Cavalieri principle on computed tomography images.

PubMed

Say, Ferhat; Gölpınar, Murat; Kılınç, Cem Yalın; Şahin, Bünyamin

2018-01-01

To evaluate the volume of bone cyst using the planimetry method of the Cavalieri principle. A retrospective analysis was carried out on data from 25 computed tomography (CT) images of patients with bone cyst. The volume of the cysts was calculated by two independent observers using the planimetry method. The procedures were repeated 1 month later by each observer. The overall mean volume of the bone cyst was 29.25 ± 25.86 cm 3 . The mean bone cyst volumes calculated by the first observer for the first and second sessions were 29.18 ± 26.14 and 29.27 ± 26.19 cm 3 , respectively. The mean bone cyst volumes calculated by the second observer for the first and second sessions were 29.32 ± 26.36 and 29.23 ± 26.36 cm 3 , respectively. Statistical analysis showed no difference and high agreement between the first and second measurements of both observers. The Bland-Altman plots showed strong intraobserver and interobserver concordance in the measurement of the bone cyst volume. The mean total time necessary to obtain the cyst volume by the two observers was 5.27 ± 2.30 min. The bone cyst of the patients can be objectively evaluated using the planimetry method of the Cavalieri principle on CT. This method showed high interobserver and intraobserver agreement. This volume measurement can be used to evaluate cyst remodeling, including complete healing and cyst recurrence.

Review of possible applications of cosmic muon tomography

NASA Astrophysics Data System (ADS)

Checchia, P.

2016-12-01

Muon radiographic methods can be used to explore inaccessible volumes profiting of the property of muons to penetrate thick materials. An extension of the muon radiographic methods, the muon scattering tomography, was proposed for the first time in 2003 and it is based on the measurement of the multiple Coulomb scattering of muons crossing the volume under investigation. In this talk, the principles of tomographic image reconstruction are first outlined and then the experimental setup and the most adequate detectors are described. A review of the possible applications of this technique is reported, with specific reference to security in transports and monitoring of industrial processes. The technique can also be used to provide precise measurements of the properties of various materials. The experimental challenge related to this activity is discussed.

First principles prediction of amorphous phases using evolutionary algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nahas, Suhas, E-mail: shsnhs@iitk.ac.in; Gaur, Anshu, E-mail: agaur@iitk.ac.in; Bhowmick, Somnath, E-mail: bsomnath@iitk.ac.in

2016-07-07

We discuss the efficacy of evolutionary method for the purpose of structural analysis of amorphous solids. At present, ab initio molecular dynamics (MD) based melt-quench technique is used and this deterministic approach has proven to be successful to study amorphous materials. We show that a stochastic approach motivated by Darwinian evolution can also be used to simulate amorphous structures. Applying this method, in conjunction with density functional theory based electronic, ionic and cell relaxation, we re-investigate two well known amorphous semiconductors, namely silicon and indium gallium zinc oxide. We find that characteristic structural parameters like average bond length and bondmore » angle are within ∼2% of those reported by ab initio MD calculations and experimental studies.« less

First principle study of UHTC ternary diboride, Cr2AlB2

NASA Astrophysics Data System (ADS)

Rastogi, Anugya; Rajpoot, Priyanka; Verma, U. P.

2018-04-01

In this paper ab-initio study of the structural, electronic and optical properties of ternary metal boride Cr2AlB2 using full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The study of structural properties shows that Cr2AlB2 is metallic in nature and have orthorhombic crystal structure. The optical properties show that it possess anisotropic behavior, which have wide applications in electricity production through concentration of solar power (CSP) technology. To the best of our knowledge, theoretical study of the optical properties of Cr2AlB2 is reported for the first time.

The journey from forensic to predictive materials science using density functional theory

DOE PAGES

Schultz, Peter A.

2017-09-12

Approximate methods for electronic structure, implemented in sophisticated computer codes and married to ever-more powerful computing platforms, have become invaluable in chemistry and materials science. The maturing and consolidation of quantum chemistry codes since the 1980s, based upon explicitly correlated electronic wave functions, has made them a staple of modern molecular chemistry. Here, the impact of first principles electronic structure in physics and materials science had lagged owing to the extra formal and computational demands of bulk calculations.

The journey from forensic to predictive materials science using density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz, Peter A.

Approximate methods for electronic structure, implemented in sophisticated computer codes and married to ever-more powerful computing platforms, have become invaluable in chemistry and materials science. The maturing and consolidation of quantum chemistry codes since the 1980s, based upon explicitly correlated electronic wave functions, has made them a staple of modern molecular chemistry. Here, the impact of first principles electronic structure in physics and materials science had lagged owing to the extra formal and computational demands of bulk calculations.

Emission properties of body-centered cubic elemental metal photocathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Tuo; Rickman, Benjamin L., E-mail: brickm2@uic.edu; Schroeder, W. Andreas

2015-04-07

A first principles analysis of photoemission is developed to explain the lower than expected rms transverse electron momentum measured using the solenoid scan technique for the body-centered cubic Group Vb (V, Nb, and Ta) and Group VIb (Cr, Mo, and W) metallic photocathodes. The density functional theory based analysis elucidates the fundamental role that the electronic band structure (and its dispersion) plays in determining the emission properties of solid-state photocathodes and includes evaluation of work function anisotropy using a thin-slab method.

Elimination of initial stress-induced curvature in a micromachined bi-material composite-layered cantilever

NASA Astrophysics Data System (ADS)

Liu, Ruiwen; Jiao, Binbin; Kong, Yanmei; Li, Zhigang; Shang, Haiping; Lu, Dike; Gao, Chaoqun; Chen, Dapeng

2013-09-01

Micro-devices with a bi-material-cantilever (BMC) commonly suffer initial curvature due to the mismatch of residual stress. Traditional corrective methods to reduce the residual stress mismatch generally involve the development of different material deposition recipes. In this paper, a new method for reducing residual stress mismatch in a BMC is proposed based on various previously developed deposition recipes. An initial material film is deposited using two or more developed deposition recipes. This first film is designed to introduce a stepped stress gradient, which is then balanced by overlapping a second material film on the first and using appropriate deposition recipes to form a nearly stress-balanced structure. A theoretical model is proposed based on both the moment balance principle and total equal strain at the interface of two adjacent layers. Experimental results and analytical models suggest that the proposed method is effective in producing multi-layer micro cantilevers that display balanced residual stresses. The method provides a generic solution to the problem of mismatched initial stresses which universally exists in micro-electro-mechanical systems (MEMS) devices based on a BMC. Moreover, the method can be incorporated into a MEMS design automation package for efficient design of various multiple material layer devices from MEMS material library and developed deposition recipes.

First-principles simulations of heat transport

NASA Astrophysics Data System (ADS)

Puligheddu, Marcello; Gygi, Francois; Galli, Giulia

2017-11-01

Advances in understanding heat transport in solids were recently reported by both experiment and theory. However an efficient and predictive quantum simulation framework to investigate thermal properties of solids, with the same complexity as classical simulations, has not yet been developed. Here we present a method to compute the thermal conductivity of solids by performing ab initio molecular dynamics at close to equilibrium conditions, which only requires calculations of first-principles trajectories and atomic forces, thus avoiding direct computation of heat currents and energy densities. In addition the method requires much shorter sequential simulation times than ordinary molecular dynamics techniques, making it applicable within density functional theory. We discuss results for a representative oxide, MgO, at different temperatures and for ordered and nanostructured morphologies, showing the performance of the method in different conditions.

First-principles calculations of lattice dynamics and thermal properties of polar solids

DOE PAGES

Wang, Yi; Shang, Shun -Li; Fang, Huazhi; ...

2016-05-13

Although the theory of lattice dynamics was established six decades ago, its accurate implementation for polar solids using the direct (or supercell, small displacement, frozen phonon) approach within the framework of density-function-theory-based first-principles calculations had been a challenge until recently. It arises from the fact that the vibration-induced polarization breaks the lattice periodicity, whereas periodic boundary conditions are required by typical first-principles calculations, leading to an artificial macroscopic electric field. In conclusion, the article reviews a mixed-space approach to treating the interactions between lattice vibration and polarization, its applications to accurately predicting the phonon and associated thermal properties, and itsmore » implementations in a number of existing phonon codes.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, J.R.; Lu, Z.; Ring, D.M.

We have examined a variety of structures for the {l_brace}510{r_brace} symmetric tilt boundary in Si and Ge, using tight-binding and first-principles calculations. These calculations show that the observed structure in Si is the lowest-energy structure, despite the fact that it is more complicated than what is necessary to preserve fourfold coordination. Contrary to calculations using a Tersoff potential, first-principles calculations show that the energy depends strongly upon the structure. A recently developed tight-binding model for Si produces results in very good agreement with the first-principles calculations. Electronic density of states calculations based upon this model show no evidence of midgapmore » states and little evidence of electronic states localized to the grain boundary. {copyright} {ital 1998} {ital The American Physical Society}« less

A weak Hamiltonian finite element method for optimal control problems

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Bless, Robert R.

1989-01-01

A temporal finite element method based on a mixed form of the Hamiltonian weak principle is developed for dynamics and optimal control problems. The mixed form of Hamilton's weak principle contains both displacements and momenta as primary variables that are expanded in terms of nodal values and simple polynomial shape functions. Unlike other forms of Hamilton's principle, however, time derivatives of the momenta and displacements do not appear therein; instead, only the virtual momenta and virtual displacements are differentiated with respect to time. Based on the duality that is observed to exist between the mixed form of Hamilton's weak principle and variational principles governing classical optimal control problems, a temporal finite element formulation of the latter can be developed in a rather straightforward manner. Several well-known problems in dynamics and optimal control are illustrated. The example dynamics problem involves a time-marching problem. As optimal control examples, elementary trajectory optimization problems are treated.

A weak Hamiltonian finite element method for optimal control problems

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Bless, Robert R.

1990-01-01

A temporal finite element method based on a mixed form of the Hamiltonian weak principle is developed for dynamics and optimal control problems. The mixed form of Hamilton's weak principle contains both displacements and momenta as primary variables that are expanded in terms of nodal values and simple polynomial shape functions. Unlike other forms of Hamilton's principle, however, time derivatives of the momenta and displacements do not appear therein; instead, only the virtual momenta and virtual displacements are differentiated with respect to time. Based on the duality that is observed to exist between the mixed form of Hamilton's weak principle and variational principles governing classical optimal control problems, a temporal finite element formulation of the latter can be developed in a rather straightforward manner. Several well-known problems in dynamics and optimal control are illustrated. The example dynamics problem involves a time-marching problem. As optimal control examples, elementary trajectory optimization problems are treated.

Weak Hamiltonian finite element method for optimal control problems

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Bless, Robert R.

1991-01-01

A temporal finite element method based on a mixed form of the Hamiltonian weak principle is developed for dynamics and optimal control problems. The mixed form of Hamilton's weak principle contains both displacements and momenta as primary variables that are expanded in terms of nodal values and simple polynomial shape functions. Unlike other forms of Hamilton's principle, however, time derivatives of the momenta and displacements do not appear therein; instead, only the virtual momenta and virtual displacements are differentiated with respect to time. Based on the duality that is observed to exist between the mixed form of Hamilton's weak principle and variational principles governing classical optimal control problems, a temporal finite element formulation of the latter can be developed in a rather straightforward manner. Several well-known problems in dynamics and optimal control are illustrated. The example dynamics problem involves a time-marching problem. As optimal control examples, elementary trajectory optimization problems are treated.

DEM interpolation weight calculation modulus based on maximum entropy

NASA Astrophysics Data System (ADS)

Chen, Tian-wei; Yang, Xia

2015-12-01

There is negative-weight in traditional interpolation of gridding DEM, in the article, the principle of Maximum Entropy is utilized to analyze the model system which depends on modulus of space weight. Negative-weight problem of the DEM interpolation is researched via building Maximum Entropy model, and adding nonnegative, first and second order's Moment constraints, the negative-weight problem is solved. The correctness and accuracy of the method was validated with genetic algorithm in matlab program. The method is compared with the method of Yang Chizhong interpolation and quadratic program. Comparison shows that the volume and scaling of Maximum Entropy's weight is fit to relations of space and the accuracy is superior to the latter two.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shen; Kang, Wei, E-mail: weikang@pku.edu.cn; College of Engineering, Peking University, Beijing 100871

An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures ofmore » plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.« less

Remote and reversible inhibition of neurons and circuits by small molecule induced potassium channel stabilization

PubMed Central

Auffenberg, Eva; Jurik, Angela; Mattusch, Corinna; Stoffel, Rainer; Genewsky, Andreas; Namendorf, Christian; Schmid, Roland M.; Rammes, Gerhard; Biel, Martin; Uhr, Manfred; Moosmang, Sven; Michalakis, Stylianos; Wotjak, Carsten T.; Thoeringer, Christoph K.

2016-01-01

Manipulating the function of neurons and circuits that translate electrical and chemical signals into behavior represents a major challenges in neuroscience. In addition to optogenetic methods using light-activatable channels, pharmacogenetic methods with ligand induced modulation of cell signaling and excitability have been developed. However, they are largely based on ectopic expression of exogenous or chimera proteins. Now, we describe the remote and reversible expression of a Kir2.1 type potassium channel using the chemogenetic technique of small molecule induced protein stabilization. Based on shield1-mediated shedding of a destabilizing domain fused to a protein of interest and inhibition of protein degradation, this principle has been adopted for biomedicine, but not in neuroscience so far. Here, we apply this chemogenetic approach in brain research for the first time in order to control a potassium channel in a remote and reversible manner. We could show that shield1-mediated ectopic Kir2.1 stabilization induces neuronal silencing in vitro and in vivo in the mouse brain. We also validated this novel pharmacogenetic method in different neurobehavioral paradigms.The DD-Kir2.1 may complement the existing portfolio of pharmaco- and optogenetic techniques for specific neuron manipulation, but it may also provide an example for future applications of this principle in neuroscience research. PMID:26757616

A Practice Approach of Multi-source Geospatial Data Integration for Web-based Geoinformation Services

NASA Astrophysics Data System (ADS)

Huang, W.; Jiang, J.; Zha, Z.; Zhang, H.; Wang, C.; Zhang, J.

2014-04-01

Geospatial data resources are the foundation of the construction of geo portal which is designed to provide online geoinformation services for the government, enterprise and public. It is vital to keep geospatial data fresh, accurate and comprehensive in order to satisfy the requirements of application and development of geographic location, route navigation, geo search and so on. One of the major problems we are facing is data acquisition. For us, integrating multi-sources geospatial data is the mainly means of data acquisition. This paper introduced a practice integration approach of multi-source geospatial data with different data model, structure and format, which provided the construction of National Geospatial Information Service Platform of China (NGISP) with effective technical supports. NGISP is the China's official geo portal which provides online geoinformation services based on internet, e-government network and classified network. Within the NGISP architecture, there are three kinds of nodes: national, provincial and municipal. Therefore, the geospatial data is from these nodes and the different datasets are heterogeneous. According to the results of analysis of the heterogeneous datasets, the first thing we do is to define the basic principles of data fusion, including following aspects: 1. location precision; 2.geometric representation; 3. up-to-date state; 4. attribute values; and 5. spatial relationship. Then the technical procedure is researched and the method that used to process different categories of features such as road, railway, boundary, river, settlement and building is proposed based on the principles. A case study in Jiangsu province demonstrated the applicability of the principle, procedure and method of multi-source geospatial data integration.

Analyzing precautionary regulation: do precaution, science, and innovation go together?

PubMed

Todt, Oliver; Luján, José Luis

2014-12-01

In this article we argue that the precautionary principle, as applied to the regulation of science and technology, cannot be considered in any general manner inconsistent with the norms and methods of scientific knowledge generation and justification. Moreover, it does not necessarily curtail scientific-technological innovation. Our argument flows from a differentiated view of what precaution in regulation means. We first characterize several of the most relevant interpretations given to the precautionary principle in academic debate and regulatory practice. We then use examples of actual precaution-based regulation to show that, even though science can have varying functions in different circumstances and frames, all of those interpretations recur to scientific method and knowledge, and tend to imply innovation in methods, products, and processes. In fact, the interplay of regulation and innovation in precautionary policy, at least in the case of the interpretations of precaution that our analysis takes into account, could be understood as a way of reconciling the two fundamental science and technology policy functions of promotion and control. © 2014 Society for Risk Analysis.

Using Participatory Action Research to Increase Learning Transfer of Recovery-Based Principles

ERIC Educational Resources Information Center

Barish, Diane J.

2009-01-01

This study questions whether or not participatory action research is an effective and practical method for increasing learning transfer of recovery-based principles. The participants (N = 250) were ethnically and educationally diverse clinicians, in an urban state mental health institute. The Self-Assessment of Recovery-Based Behaviors survey ( n…

Numerical simulations of electrohydrodynamic evolution of thin polymer films

NASA Astrophysics Data System (ADS)

Borglum, Joshua Christopher

Recently developed needleless electrospinning and electrolithography are two successful techniques that have been utilized extensively for low-cost, scalable, and continuous nano-fabrication. Rational understanding of the electrohydrodynamic principles underneath these nano-manufacturing methods is crucial to fabrication of continuous nanofibers and patterned thin films. This research project is to formulate robust, high-efficiency finite-difference Fourier spectral methods to simulate the electrohydrodynamic evolution of thin polymer films. Two thin-film models were considered and refined. The first was based on reduced lubrication theory; the second further took into account the effect of solvent drying and dewetting of the substrate. Fast Fourier Transform (FFT) based spectral method was integrated into the finite-difference algorithms for fast, accurately solving the governing nonlinear partial differential equations. The present methods have been used to examine the dependencies of the evolving surface features of the thin films upon the model parameters. The present study can be used for fast, controllable nanofabrication.

Efficient Terahertz Wide-Angle NUFFT-Based Inverse Synthetic Aperture Imaging Considering Spherical Wavefront.

PubMed

Gao, Jingkun; Deng, Bin; Qin, Yuliang; Wang, Hongqiang; Li, Xiang

2016-12-14

An efficient wide-angle inverse synthetic aperture imaging method considering the spherical wavefront effects and suitable for the terahertz band is presented. Firstly, the echo signal model under spherical wave assumption is established, and the detailed wavefront curvature compensation method accelerated by 1D fast Fourier transform (FFT) is discussed. Then, to speed up the reconstruction procedure, the fast Gaussian gridding (FGG)-based nonuniform FFT (NUFFT) is employed to focus the image. Finally, proof-of-principle experiments are carried out and the results are compared with the ones obtained by the convolution back-projection (CBP) algorithm. The results demonstrate the effectiveness and the efficiency of the presented method. This imaging method can be directly used in the field of nondestructive detection and can also be used to provide a solution for the calculation of the far-field RCSs (Radar Cross Section) of targets in the terahertz regime.

What really separates casuistry from principlism in biomedical ethics.

PubMed

Cudney, Paul

2014-06-01

Since the publication of the first edition of Tom Beauchamp and James Childress's Principles of Biomedical Ethics there has been much debate about what a proper method in medical ethics should look like. The main rival for Beauchamp and Childress's account, principlism, has consistently been casuistry, an account that recommends argument by analogy from paradigm cases. Admirably, Beauchamp and Childress have modified their own view in successive editions of Principles of Biomedical Ethics in order to address the concerns proponents of casuistry and others have had about principlism. Given these adjustments to their view, some have claimed that principlism and casuistry no longer count as distinct methods. Even so, many still consider these two conceptions of bioethical methodologies as rivals. Both accounts of the relationship between casuistry and principlism are wrong. These two conceptions of methodology in biomedical ethics are significantly different, but the differences are not the ones pointed out by those who still claim that they are distinct positions. In this article, I explain where the real similarities and differences lie between these two views.

Universal method to calculate the stability, electronegativity, and hardness of dianions.

PubMed

von Szentpály, László

2010-10-14

The electronic stability of gas-phase dianions of arbitrary size, X(2-), is determined by the first universal method to calculate second electron affinities, A(2). The model expresses A(2,calc) = A(1) - (7/6)η(0) by the first electron affinity, A(1), and chemical hardness, η(0), of the neutral "grandparent" species. A comparison with 37 reference data of atoms, molecules, superatoms, and clusters yields A(2,ref) = 1.004A(2,calc) - 0.023 eV, with a mean unsigned deviation of MUD = 0.095 eV and a correlation coefficient of R = 0.9987. Predictions of second electron affinities are given for a further 24 species. The universality of the model is apparent from the broad variety of compounds formed by 30 diverse elements. The electronegativity and hardness of dianions are determined for the first time as χ(X(2-)) = A(2) and η(X(2-)) = (7/12)η(0), respectively. Pearson and Parr's operational assumption regarding the hardness of anionic bases for the hard-soft acid-base (HSAB) principle is rationalized, and predictions for hard and soft dianionic bases are presented. For trianions, first criteria and predictions for electronic stability are given and require A(1) > (7/4)η(0).

Dispersion correction derived from first principles for density functional theory and Hartree-Fock theory.

PubMed

Guidez, Emilie B; Gordon, Mark S

2015-03-12

The modeling of dispersion interactions in density functional theory (DFT) is commonly performed using an energy correction that involves empirically fitted parameters for all atom pairs of the system investigated. In this study, the first-principles-derived dispersion energy from the effective fragment potential (EFP) method is implemented for the density functional theory (DFT-D(EFP)) and Hartree-Fock (HF-D(EFP)) energies. Overall, DFT-D(EFP) performs similarly to the semiempirical DFT-D corrections for the test cases investigated in this work. HF-D(EFP) tends to underestimate binding energies and overestimate intermolecular equilibrium distances, relative to coupled cluster theory, most likely due to incomplete accounting for electron correlation. Overall, this first-principles dispersion correction yields results that are in good agreement with coupled-cluster calculations at a low computational cost.

A Computationally Efficient Method for Polyphonic Pitch Estimation

NASA Astrophysics Data System (ADS)

Zhou, Ruohua; Reiss, Joshua D.; Mattavelli, Marco; Zoia, Giorgio

2009-12-01

This paper presents a computationally efficient method for polyphonic pitch estimation. The method employs the Fast Resonator Time-Frequency Image (RTFI) as the basic time-frequency analysis tool. The approach is composed of two main stages. First, a preliminary pitch estimation is obtained by means of a simple peak-picking procedure in the pitch energy spectrum. Such spectrum is calculated from the original RTFI energy spectrum according to harmonic grouping principles. Then the incorrect estimations are removed according to spectral irregularity and knowledge of the harmonic structures of the music notes played on commonly used music instruments. The new approach is compared with a variety of other frame-based polyphonic pitch estimation methods, and results demonstrate the high performance and computational efficiency of the approach.

Prism-based single-camera system for stereo display

NASA Astrophysics Data System (ADS)

Zhao, Yue; Cui, Xiaoyu; Wang, Zhiguo; Chen, Hongsheng; Fan, Heyu; Wu, Teresa

2016-06-01

This paper combines the prism and single camera and puts forward a method of stereo imaging with low cost. First of all, according to the principle of geometrical optics, we can deduce the relationship between the prism single-camera system and dual-camera system, and according to the principle of binocular vision we can deduce the relationship between binoculars and dual camera. Thus we can establish the relationship between the prism single-camera system and binoculars and get the positional relation of prism, camera, and object with the best effect of stereo display. Finally, using the active shutter stereo glasses of NVIDIA Company, we can realize the three-dimensional (3-D) display of the object. The experimental results show that the proposed approach can make use of the prism single-camera system to simulate the various observation manners of eyes. The stereo imaging system, which is designed by the method proposed by this paper, can restore the 3-D shape of the object being photographed factually.

Has Stewart approach improved our ability to diagnose acid-base disorders in critically ill patients?

PubMed

Masevicius, Fabio D; Dubin, Arnaldo

2015-02-04

The Stewart approach-the application of basic physical-chemical principles of aqueous solutions to blood-is an appealing method for analyzing acid-base disorders. These principles mainly dictate that pH is determined by three independent variables, which change primarily and independently of one other. In blood plasma in vivo these variables are: (1) the PCO2; (2) the strong ion difference (SID)-the difference between the sums of all the strong (i.e., fully dissociated, chemically nonreacting) cations and all the strong anions; and (3) the nonvolatile weak acids (Atot). Accordingly, the pH and the bicarbonate levels (dependent variables) are only altered when one or more of the independent variables change. Moreover, the source of H(+) is the dissociation of water to maintain electroneutrality when the independent variables are modified. The basic principles of the Stewart approach in blood, however, have been challenged in different ways. First, the presumed independent variables are actually interdependent as occurs in situations such as: (1) the Hamburger effect (a chloride shift when CO2 is added to venous blood from the tissues); (2) the loss of Donnan equilibrium (a chloride shift from the interstitium to the intravascular compartment to balance the decrease of Atot secondary to capillary leak; and (3) the compensatory response to a primary disturbance in either independent variable. Second, the concept of water dissociation in response to changes in SID is controversial and lacks experimental evidence. In addition, the Stewart approach is not better than the conventional method for understanding acid-base disorders such as hyperchloremic metabolic acidosis secondary to a chloride-rich-fluid load. Finally, several attempts were performed to demonstrate the clinical superiority of the Stewart approach. These studies, however, have severe methodological drawbacks. In contrast, the largest study on this issue indicated the interchangeability of the Stewart and conventional methods. Although the introduction of the Stewart approach was a new insight into acid-base physiology, the method has not significantly improved our ability to understand, diagnose, and treat acid-base alterations in critically ill patients.

First principles and metadynamics study of the spin-reorientation transition in Fe/Au(001) films

NASA Astrophysics Data System (ADS)

Nagyfalusi, B.; Udvardi, L.; Szunyogh, L.

2017-10-01

Based on first principles calculations, we investigate the magnetic anisotropy and spin reorientation transition (SRT) for Fe n /Au(001) (n=2,3) films. The SRT occurs at three atomic layer of Fe in agreement with experiments due to competing on-site and two-site anisotropy. We also study the temperature dependence of the magnetic anisotropy energy (MAE) by means of metadynamics Monte Carlo simulations.

An hp symplectic pseudospectral method for nonlinear optimal control

NASA Astrophysics Data System (ADS)

Peng, Haijun; Wang, Xinwei; Li, Mingwu; Chen, Biaosong

2017-01-01

An adaptive symplectic pseudospectral method based on the dual variational principle is proposed and is successfully applied to solving nonlinear optimal control problems in this paper. The proposed method satisfies the first order necessary conditions of continuous optimal control problems, also the symplectic property of the original continuous Hamiltonian system is preserved. The original optimal control problem is transferred into a set of nonlinear equations which can be solved easily by Newton-Raphson iterations, and the Jacobian matrix is found to be sparse and symmetric. The proposed method, on one hand, exhibits exponent convergence rates when the number of collocation points are increasing with the fixed number of sub-intervals; on the other hand, exhibits linear convergence rates when the number of sub-intervals is increasing with the fixed number of collocation points. Furthermore, combining with the hp method based on the residual error of dynamic constraints, the proposed method can achieve given precisions in a few iterations. Five examples highlight the high precision and high computational efficiency of the proposed method.

A Comparative Analysis of the Minuteman Education Programs as Currently Offered at Six SAC Bases.

DTIC Science & Technology

1980-06-01

Principles of Marketing 3 Business Statistics 3 Business Law 3 Management Total... Principles of Marketing 3 Mathematics Methods I Total prerequisite hours 26 Required Graduate Courses Policy Formulation and Administration 3 Management...Business and Economic Statistics 3 Intermediate Business and Economic Statistics 3 Principles of Management 3 Corporation Finance 3 Principles of Marketing

Principles of scarce medical resource allocation in natural disaster relief: a simulation approach.

PubMed

Cao, Hui; Huang, Simin

2012-01-01

A variety of triage principles have been proposed. The authors sought to evaluate their effects on how many lives can be saved in a hypothetical disaster. To determine an optimal scarce resource-rationing principle in the emergency response domain, considering the trade-off between lifesaving efficiency and ethical issues. A discrete event simulation model is developed to examine the efficiency of four resource-rationing principles: first come-first served, random, most serious first, and least serious first. Seven combinations of available resources are examined in the simulations to evaluate the performance of the principles under different levels of resource scarcity. The simulation results indicate that the performance of the medical resource allocation principles is related to the level of the resource scarcity. When the level of the scarcity is high, the performances of the four principles differ significantly. The least serious first principle performs best, followed by the random principle; the most serious first principle acts worst. However, when the scarcity is relieved, there are no significant differences among the random, first come-first served, and least serious first principles, yet the most serious first principle still performs worst. Although the least serious first principle exhibits the highest efficiency, it is not ethically flawless. Considering the trade off between the lifesaving efficiency and the ethical issues, random selection is a relatively fair and efficient principle for allocating scarce medical resources in natural disaster responses.

A new method of search design of refrigerating systems containing a liquid and gaseous working medium based on the graph model of the physical operating principle

NASA Astrophysics Data System (ADS)

Yakovlev, A. A.; Sorokin, V. S.; Mishustina, S. N.; Proidakova, N. V.; Postupaeva, S. G.

2017-01-01

The article describes a new method of search design of refrigerating systems, the basis of which is represented by a graph model of the physical operating principle based on thermodynamical description of physical processes. The mathematical model of the physical operating principle has been substantiated, and the basic abstract theorems relatively semantic load applied to nodes and edges of the graph have been represented. The necessity and the physical operating principle, sufficient for the given model and intended for the considered device class, were demonstrated by the example of a vapour-compression refrigerating plant. The example of obtaining a multitude of engineering solutions of a vapour-compression refrigerating plant has been considered.

Towards Efficient and Accurate Description of Many-Electron Problems: Developments of Static and Time-Dependent Electronic Structure Methods

NASA Astrophysics Data System (ADS)

Ding, Feizhi

Understanding electronic behavior in molecular and nano-scale systems is fundamental to the development and design of novel technologies and materials for application in a variety of scientific contexts from fundamental research to energy conversion. This dissertation aims to provide insights into this goal by developing novel methods and applications of first-principle electronic structure theory. Specifically, we will present new methods and applications of excited state multi-electron dynamics based on the real-time (RT) time-dependent Hartree-Fock (TDHF) and time-dependent density functional theory (TDDFT) formalism, and new development of the multi-configuration self-consist field theory (MCSCF) for modeling ground-state electronic structure. The RT-TDHF/TDDFT based developments and applications can be categorized into three broad and coherently integrated research areas: (1) modeling of the interaction between moleculars and external electromagnetic perturbations. In this part we will first prove both analytically and numerically the gauge invariance of the TDHF/TDDFT formalisms, then we will present a novel, efficient method for calculating molecular nonlinear optical properties, and last we will study quantum coherent plasmon in metal namowires using RT-TDDFT; (2) modeling of excited-state charge transfer in molecules. In this part, we will investigate the mechanisms of bridge-mediated electron transfer, and then we will introduce a newly developed non-equilibrium quantum/continuum embedding method for studying charge transfer dynamics in solution; (3) developments of first-principles spin-dependent many-electron dynamics. In this part, we will present an ab initio non-relativistic spin dynamics method based on the two-component generalized Hartree-Fock approach, and then we will generalized it to the two-component TDDFT framework and combine it with the Ehrenfest molecular dynamics approach for modeling the interaction between electron spins and nuclear motion. All these developments and applications will open up new computational and theoretical tools to be applied to the development and understanding of chemical reactions, nonlinear optics, electromagnetism, and spintronics. Lastly, we present a new algorithm for large-scale MCSCF calculations that can utilize massively parallel machines while still maintaining optimal performance for each single processor. This will great improve the efficiency in the MCSCF calculations for studying chemical dissociation and high-accuracy quantum-mechanical simulations.

Next Generation Extended Lagrangian Quantum-based Molecular Dynamics

NASA Astrophysics Data System (ADS)

Negre, Christian

2017-06-01

A new framework for extended Lagrangian first-principles molecular dynamics simulations is presented, which overcomes shortcomings of regular, direct Born-Oppenheimer molecular dynamics, while maintaining important advantages of the unified extended Lagrangian formulation of density functional theory pioneered by Car and Parrinello three decades ago. The new framework allows, for the first time, energy conserving, linear-scaling Born-Oppenheimer molecular dynamics simulations, which is necessary to study larger and more realistic systems over longer simulation times than previously possible. Expensive, self-consinstent-field optimizations are avoided and normal integration time steps of regular, direct Born-Oppenheimer molecular dynamics can be used. Linear scaling electronic structure theory is presented using a graph-based approach that is ideal for parallel calculations on hybrid computer platforms. For the first time, quantum based Born-Oppenheimer molecular dynamics simulation is becoming a practically feasible approach in simulations of +100,000 atoms-representing a competitive alternative to classical polarizable force field methods. In collaboration with: Anders Niklasson, Los Alamos National Laboratory.

Study of the extra-ionic electron distributions in semi-metallic structures by nuclear quadrupole resonance techniques

NASA Technical Reports Server (NTRS)

Murty, A. N.

1976-01-01

A straightforward self-consistent method was developed to estimate solid state electrostatic potentials, fields and field gradients in ionic solids. The method is a direct practical application of basic electrostatics to solid state and also helps in the understanding of the principles of crystal structure. The necessary mathematical equations, derived from first principles, were presented and the systematic computational procedure developed to arrive at the solid state electrostatic field gradients values was given.

Applying the four principles

PubMed Central

Macklin, R

2003-01-01

Gillon is correct that the four principles provide a sound and useful way of analysing moral dilemmas. As he observes, the approach using these principles does not provide a unique solution to dilemmas. This can be illustrated by alternatives to Gillon's own analysis of the four case scenarios. In the first scenario, a different set of factual assumptions could yield a different conclusion about what is required by the principle of beneficence. In the second scenario, although Gillon's conclusion is correct, what is open to question is his claim that what society regards as the child's best interest determines what really is in the child's best interest. The third scenario shows how it may be reasonable for the principle of beneficence to take precedence over autonomy in certain circumstances, yet like the first scenario, the ethical conclusion relies on a set of empirical assumptions and predictions of what is likely to occur. The fourth scenario illustrates how one can draw different conclusions based on the importance given to the precautionary principle. PMID:14519836

Applying the four principles.

PubMed

Macklin, R

2003-10-01

Gillon is correct that the four principles provide a sound and useful way of analysing moral dilemmas. As he observes, the approach using these principles does not provide a unique solution to dilemmas. This can be illustrated by alternatives to Gillon's own analysis of the four case scenarios. In the first scenario, a different set of factual assumptions could yield a different conclusion about what is required by the principle of beneficence. In the second scenario, although Gillon's conclusion is correct, what is open to question is his claim that what society regards as the child's best interest determines what really is in the child's best interest. The third scenario shows how it may be reasonable for the principle of beneficence to take precedence over autonomy in certain circumstances, yet like the first scenario, the ethical conclusion relies on a set of empirical assumptions and predictions of what is likely to occur. The fourth scenario illustrates how one can draw different conclusions based on the importance given to the precautionary principle.

Theoretical Understanding the Relations of Melting-point Determination Methods from Gibbs Thermodynamic Surface and Applications on Melting Curves of Lower Mantle Minerals

NASA Astrophysics Data System (ADS)

Yin, K.; Belonoshko, A. B.; Zhou, H.; Lu, X.

2016-12-01

The melting temperatures of materials in the interior of the Earth has significant implications in many areas of geophysics. The direct calculations of the melting point by atomic simulations would face substantial hysteresis problem. To overcome the hysteresis encountered in the atomic simulations there are a few different melting-point determination methods available nowadays, which are founded independently, such as the free energy method, the two-phase or coexistence method, and the Z method, etc. In this study, we provide a theoretical understanding the relations of these methods from a geometrical perspective based on a quantitative construction of the volume-entropy-energy thermodynamic surface, a model first proposed by J. Willard Gibbs in 1873. Then combining with an experimental data and/or a previous melting-point determination method, we apply this model to derive the high-pressure melting curves for several lower mantle minerals with less computational efforts relative to using previous methods only. Through this way, some polyatomic minerals at extreme pressures which are almost unsolvable before are calculated fully from first principles now.

Fast auto-focus scheme based on optical defocus fitting model

NASA Astrophysics Data System (ADS)

Wang, Yeru; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting; Cen, Min

2018-04-01

An optical defocus fitting model-based (ODFM) auto-focus scheme is proposed. Considering the basic optical defocus principle, the optical defocus fitting model is derived to approximate the potential-focus position. By this accurate modelling, the proposed auto-focus scheme can make the stepping motor approach the focal plane more accurately and rapidly. Two fitting positions are first determined for an arbitrary initial stepping motor position. Three images (initial image and two fitting images) at these positions are then collected to estimate the potential-focus position based on the proposed ODFM method. Around the estimated potential-focus position, two reference images are recorded. The auto-focus procedure is then completed by processing these two reference images and the potential-focus image to confirm the in-focus position using a contrast based method. Experimental results prove that the proposed scheme can complete auto-focus within only 5 to 7 steps with good performance even under low-light condition.

Size-independent neural networks based first-principles method for accurate prediction of heat of formation of fuels

NASA Astrophysics Data System (ADS)

Yang, GuanYa; Wu, Jiang; Chen, ShuGuang; Zhou, WeiJun; Sun, Jian; Chen, GuanHua

2018-06-01

Neural network-based first-principles method for predicting heat of formation (HOF) was previously demonstrated to be able to achieve chemical accuracy in a broad spectrum of target molecules [L. H. Hu et al., J. Chem. Phys. 119, 11501 (2003)]. However, its accuracy deteriorates with the increase in molecular size. A closer inspection reveals a systematic correlation between the prediction error and the molecular size, which appears correctable by further statistical analysis, calling for a more sophisticated machine learning algorithm. Despite the apparent difference between simple and complex molecules, all the essential physical information is already present in a carefully selected set of small molecule representatives. A model that can capture the fundamental physics would be able to predict large and complex molecules from information extracted only from a small molecules database. To this end, a size-independent, multi-step multi-variable linear regression-neural network-B3LYP method is developed in this work, which successfully improves the overall prediction accuracy by training with smaller molecules only. And in particular, the calculation errors for larger molecules are drastically reduced to the same magnitudes as those of the smaller molecules. Specifically, the method is based on a 164-molecule database that consists of molecules made of hydrogen and carbon elements. 4 molecular descriptors were selected to encode molecule's characteristics, among which raw HOF calculated from B3LYP and the molecular size are also included. Upon the size-independent machine learning correction, the mean absolute deviation (MAD) of the B3LYP/6-311+G(3df,2p)-calculated HOF is reduced from 16.58 to 1.43 kcal/mol and from 17.33 to 1.69 kcal/mol for the training and testing sets (small molecules), respectively. Furthermore, the MAD of the testing set (large molecules) is reduced from 28.75 to 1.67 kcal/mol.

Liquid li structure and dynamics: A comparison between OFDFT and second nearest-neighbor embedded-atom method

DOE PAGES

Chen, Mohan; Vella, Joseph R.; Panagiotopoulos, Athanassios Z.; ...

2015-04-08

The structure and dynamics of liquid lithium are studied using two simulation methods: orbital-free (OF) first-principles molecular dynamics (MD), which employs OF density functional theory (DFT), and classical MD utilizing a second nearest-neighbor embedded-atom method potential. The properties we studied include the dynamic structure factor, the self-diffusion coefficient, the dispersion relation, the viscosity, and the bond angle distribution function. Our simulation results were compared to available experimental data when possible. Each method has distinct advantages and disadvantages. For example, OFDFT gives better agreement with experimental dynamic structure factors, yet is more computationally demanding than classical simulations. Classical simulations can accessmore » a broader temperature range and longer time scales. The combination of first-principles and classical simulations is a powerful tool for studying properties of liquid lithium.« less

First-principles calculations reveal controlling principles for carrier mobilities in semiconductors

DOE PAGES

Wu, Yu -Ning; Zhang, Xiaoguang; Pantelides, Sokrates T.; ...

2016-10-11

It has long been believed that carrier mobilities in semiconductors can be calculated by Fermi s golden rule (Born approximation). Phenomenological models for scattering amplitudes are typically used for engineering- level device modeling. Here we introduce a parameter-free, first-principles approach based on complex- wavevector energy bands that does not invoke the Born approximation. We show that phonon-limited mobility is controlled by low-resistivity percolation paths and that in ionized-impurity scattering one must account for the effect of the screening charge, which cancels most of the Coulomb tail.Finally, calculated electron mobilities in silicon are in agreement with experimental data.

First-principles investigation on switching properties of spiropyran and merocyanine grafted graphyne nanotube device

NASA Astrophysics Data System (ADS)

Bhuvaneswari, R.; Nagarajan, V.; Chandiramouli, R.

2018-01-01

The density functional theory (DFT) method with non-equilibrium Green's function (NEGF) method is used to study the electronic properties of the graphyne nanotube device. The graphyne nanotube is used as a base material to graft photochromic spiropyran and merocyanine molecules. The current voltage characteristics clearly give the insights on the switching properties of spiropyran and merocyanine grafted graphyne device. The findings show that spiropyran grafted graphyne device as ON state and merocyanine grafted graphyne device as an OFF state device. Moreover, upon shining light of proper wavelength, the spiropyran/merocyanine grafted graphyne nanotube device can be used as a switch.

Physical Principles of the Method for Determination of Geometrical Characteristics and Particle Recognition in Digital Holography

NASA Astrophysics Data System (ADS)

Dyomin, V. V.; Polovtsev, I. G.; Davydova, A. Yu.

2018-03-01

The physical principles of a method for determination of geometrical characteristics of particles and particle recognition based on the concepts of digital holography, followed by processing of the particle images reconstructed from the digital hologram, using the morphological parameter are reported. An example of application of this method for fast plankton particle recognition is given.

Novel method of detecting movement of the interference fringes using one-dimensional PSD.

PubMed

Wang, Qi; Xia, Ji; Liu, Xu; Zhao, Yong

2015-06-02

In this paper, a method of using a one-dimensional position-sensitive detector (PSD) by replacing charge-coupled device (CCD) to measure the movement of the interference fringes is presented first, and its feasibility is demonstrated through an experimental setup based on the principle of centroid detection. Firstly, the centroid position of the interference fringes in a fiber Mach-Zehnder (M-Z) interferometer is solved in theory, showing it has a higher resolution and sensitivity. According to the physical characteristics and principles of PSD, a simulation of the interference fringe's phase difference in fiber M-Z interferometers and PSD output is carried out. Comparing the simulation results with the relationship between phase differences and centroid positions in fiber M-Z interferometers, the conclusion that the output of interference fringes by PSD is still the centroid position is obtained. Based on massive measurements, the best resolution of the system is achieved with 5.15, 625 μm. Finally, the detection system is evaluated through setup error analysis and an ultra-narrow-band filter structure. The filter structure is configured with a one-dimensional photonic crystal containing positive and negative refraction material, which can eliminate background light in the PSD detection experiment. This detection system has a simple structure, good stability, high precision and easily performs remote measurements, which makes it potentially useful in material small deformation tests, refractivity measurements of optical media and optical wave front detection.

A first-principles and experimental study of helium diffusion in periclase MgO

NASA Astrophysics Data System (ADS)

Song, Zhewen; Wu, Henry; Shu, Shipeng; Krawczynski, Mike; Van Orman, James; Cherniak, Daniele J.; Bruce Watson, E.; Mukhopadhyay, Sujoy; Morgan, Dane

2018-02-01

The distribution of He isotopes is used to trace heterogeneities in the Earth's mantle, and is particularly useful for constraining the length scale of heterogeneity due to the generally rapid diffusivity of helium. However, such an analysis is challenging because He diffusivities are largely unknown in lower mantle phases, which can influence the He profiles in regions that cycle through the lower mantle. With this motivation, we have used first-principles simulations based on density functional theory to study He diffusion in MgO, an important lower mantle phase. We first studied the case of interstitial helium diffusion in perfect MgO and found a migration barrier of 0.73 eV at zero pressure. Then we used the kinetic Monte Carlo method to study the case of substitutional He diffusion in MgO, where we assumed that He diffuses on the cation sublattice through cation vacancies. We also performed experiments on He diffusion at atmospheric pressure using ion implantation and nuclear reaction analysis in both as-received and Ga-doped samples. A comparison between the experimental and simulation results are shown. This work provides a foundation for further studies at high-pressure.

A Near-Infrared Spectrometer Based on Novel Grating Light Modulators

PubMed Central

Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

2009-01-01

A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification. PMID:22574065

A near-infrared spectrometer based on novel grating light modulators.

PubMed

Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

2009-01-01

A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification.

Principles of cooperation across systems: from human sharing to multicellularity and cancer.

PubMed

Aktipis, Athena

2016-01-01

From cells to societies, several general principles arise again and again that facilitate cooperation and suppress conflict. In this study, I describe three general principles of cooperation and how they operate across systems including human sharing, cooperation in animal and insect societies and the massively large-scale cooperation that occurs in our multicellular bodies. The first principle is that of Walk Away: that cooperation is enhanced when individuals can leave uncooperative partners. The second principle is that resource sharing is often based on the need of the recipient (i.e., need-based transfers) rather than on strict account-keeping. And the last principle is that effective scaling up of cooperation requires increasingly sophisticated and costly cheater suppression mechanisms. By comparing how these principles operate across systems, we can better understand the constraints on cooperation. This can facilitate the discovery of novel ways to enhance cooperation and suppress cheating in its many forms, from social exploitation to cancer.

Threshold multi-secret sharing scheme based on phase-shifting interferometry

NASA Astrophysics Data System (ADS)

Deng, Xiaopeng; Wen, Wei; Shi, Zhengang

2017-03-01

A threshold multi-secret sharing scheme is proposed based on phase-shifting interferometry. The K secret images to be shared are firstly encoded by using Fourier transformation, respectively. Then, these encoded images are shared into many shadow images based on recording principle of the phase-shifting interferometry. In the recovering stage, the secret images can be restored by combining any 2 K + 1 or more shadow images, while any 2 K or fewer shadow images cannot obtain any information about the secret images. As a result, a (2 K + 1 , N) threshold multi-secret sharing scheme can be implemented. Simulation results are presented to demonstrate the feasibility of the proposed method.

Course constructions: A case-base of forensic toxicology.

PubMed

Zhou, Nan; Wu, Yeda; Su, Terry; Zhang, Liyong; Yin, Kun; Zheng, Da; Zheng, Jingjing; Huang, Lei; Wu, Qiuping; Cheng, Jianding

2017-08-01

Forensic toxicology education in China is limited by insufficient teaching methods and resources, resulting in students with adequate theoretical principles but lacking practice experience. Typical cases used as teaching materials vividly represent intoxication and provide students with an opportunity to practice and hone resolving skills. In 2013, the Department of Forensic Pathology at Zhongshan School of Medicine began to construct top-quality courses in forensic toxicology, with its first step, creating a base containing typical cases of intoxication. This essay reviews the construction process of said cases-base, which is intended to set an example of forensic toxicology education. Copyright © 2017 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Second principle approach to the analysis of unsteady flow and heat transfer in a tube with arc-shaped corrugation

NASA Astrophysics Data System (ADS)

Pagliarini, G.; Vocale, P.; Mocerino, A.; Rainieri, S.

2017-01-01

Passive convective heat transfer enhancement techniques are well known and widespread tool for increasing the efficiency of heat transfer equipment. In spite of the ability of the first principle approach to forecast the macroscopic effects of the passive techniques for heat transfer enhancement, namely the increase of both the overall heat exchanged and the head losses, a first principle analysis based on energy, momentum and mass local conservation equations is hardly able to give a comprehensive explanation of how local modifications in the boundary layers contribute to the overall effect. A deeper insight on the heat transfer enhancement mechanisms can be instead obtained within a second principle approach, through the analysis of the local exergy dissipation phenomena which are related to heat transfer and fluid flow. To this aim, the analysis based on the second principle approach implemented through a careful consideration of the local entropy generation rate seems the most suitable, since it allows to identify more precisely the cause of the loss of efficiency in the heat transfer process, thus providing a useful guide in the choice of the most suitable heat transfer enhancement techniques.

Bending and buckling formulation of graphene sheets based on nonlocal simple first-order shear deformation theory

NASA Astrophysics Data System (ADS)

Golmakani, M. E.; Malikan, M.; Sadraee Far, M. N.; Majidi, H. R.

2018-06-01

This paper presents a formulation based on simple first-order shear deformation theory (S-FSDT) for large deflection and buckling of orthotropic single-layered graphene sheets (SLGSs). The S-FSDT has many advantages compared to the classical plate theory (CPT) and conventional FSDT such as needless of shear correction factor, containing less number of unknowns than the existing FSDT and strong similarities with the CPT. Governing equations and boundary conditions are derived based on Hamilton’s principle using the nonlocal differential constitutive relations of Eringen and von Kármán geometrical model. Numerical results are obtained using differential quadrature (DQ) method and the Newton–Raphson iterative scheme. Finally, some comparison studies are carried out to show the high accuracy and reliability of the present formulations compared to the nonlocal CPT and FSDT for different thicknesses, elastic foundations and nonlocal parameters.

Multipole-Based Cable Braid Electromagnetic Penetration Model: Electric Penetration Case

DOE PAGES

Campione, Salvatore; Warne, Larry K.; Langston, William L.; ...

2017-07-11

In this paper, we investigate the electric penetration case of the first principles multipole-based cable braid electromagnetic penetration model reported in the Progress in Electromagnetics Research B 66, 63–89 (2016). We first analyze the case of a 1-D array of wires: this is a problem which is interesting on its own, and we report its modeling based on a multipole-conformal mapping expansion and extension by means of Laplace solutions in bipolar coordinates. We then compare the elastance (inverse of capacitance) results from our first principles cable braid electromagnetic penetration model to that obtained using the multipole-conformal mapping bipolar solution. Thesemore » results are found in a good agreement up to a radius to half spacing ratio of 0.6, demonstrating a robustness needed for many commercial cables. We then analyze realistic cable implementations without dielectrics and compare the results from our first principles braid electromagnetic penetration model to the semiempirical results reported by Kley in the IEEE Transactions on Electromagnetic Compatibility 35, 1–9 (1993). Finally, although we find results on the same order of magnitude of Kley's results, the full dependence on the actual cable geometry is accounted for only in our proposed multipole model which, in addition, enables us to treat perturbations from those commercial cables measured.« less

Multipole-Based Cable Braid Electromagnetic Penetration Model: Electric Penetration Case

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campione, Salvatore; Warne, Larry K.; Langston, William L.

In this paper, we investigate the electric penetration case of the first principles multipole-based cable braid electromagnetic penetration model reported in the Progress in Electromagnetics Research B 66, 63–89 (2016). We first analyze the case of a 1-D array of wires: this is a problem which is interesting on its own, and we report its modeling based on a multipole-conformal mapping expansion and extension by means of Laplace solutions in bipolar coordinates. We then compare the elastance (inverse of capacitance) results from our first principles cable braid electromagnetic penetration model to that obtained using the multipole-conformal mapping bipolar solution. Thesemore » results are found in a good agreement up to a radius to half spacing ratio of 0.6, demonstrating a robustness needed for many commercial cables. We then analyze realistic cable implementations without dielectrics and compare the results from our first principles braid electromagnetic penetration model to the semiempirical results reported by Kley in the IEEE Transactions on Electromagnetic Compatibility 35, 1–9 (1993). Finally, although we find results on the same order of magnitude of Kley's results, the full dependence on the actual cable geometry is accounted for only in our proposed multipole model which, in addition, enables us to treat perturbations from those commercial cables measured.« less

First-principles study of low-spin LaCoO3 with structurally consistent Hubbard U

NASA Astrophysics Data System (ADS)

Hsu, H.; Umemoto, K.; Cococcioni, M.; Wentzcovitch, R.

2008-12-01

We use the local density approximation + Hubbard U (LDA+U) method to calculate the structural and electronic properties of low-spin LaCoO3. The Hubbard U is obtained by first principles and consistent with each fully-optimized atomic structure at different pressures. With structurally consistent U, the fully-optimized atomic structure agrees with experimental data better than the calculations with fixed or vanishing U. A discussion on how the Hubbard U affects the electronic and atomic structure of LaCoO3 is also given.

Neutral and charged excitations in carbon fullerenes from first-principles many-body theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiago, Murilo L; Kent, Paul R; Hood, Randolph Q.

2008-01-01

We use first-principles many-body theories to investigate the low energy excitations of the carbon fullerenes C_20, C_24, C_50, C_60, C_70, and C_80. Properties are calculated via the GW-Bethe-Salpeter Equation (GW-BSE) and diffusion Quantum Monte Carlo (QMC) methods. At a lower level of theoretical complexity, we also calculate these properties using static and time-dependent density-functional theory. We critically compare these theories and assess their accuracy against available experimental data. The first ionization potentials are consistently well reproduced and are similar for all the fullerenes and methods studied. The electron affinities and first triplet excitation energies show substantial method and geometry dependence.more » Compared to available experiment, GW-BSE underestimates excitation energies by approximately 0.3 eV while QMC overestimates them by approximately 0.5 eV. We show the GW-BSE errors result primarily from a systematic overestimation of the electron affinities, while the QMC errors likely result from nodal error in both ground and excited state calculations.« less

Digital Mirror Device Application in Reduction of Wave-front Phase Errors

PubMed Central

Zhang, Yaping; Liu, Yan; Wang, Shuxue

2009-01-01

In order to correct the image distortion created by the mixing/shear layer, creative and effectual correction methods are necessary. First, a method combining adaptive optics (AO) correction with a digital micro-mirror device (DMD) is presented. Second, performance of an AO system using the Phase Diverse Speckle (PDS) principle is characterized in detail. Through combining the DMD method with PDS, a significant reduction in wavefront phase error is achieved in simulations and experiments. This kind of complex correction principle can be used to recovery the degraded images caused by unforeseen error sources. PMID:22574016

Disordered crystals from first principles I: Quantifying the configuration space

NASA Astrophysics Data System (ADS)

Kühne, Thomas D.; Prodan, Emil

2018-04-01

This work represents the first chapter of a project on the foundations of first-principle calculations of the electron transport in crystals at finite temperatures. We are interested in the range of temperatures, where most electronic components operate, that is, room temperature and above. The aim is a predictive first-principle formalism that combines ab-initio molecular dynamics and a finite-temperature Kubo-formula for homogeneous thermodynamic phases. The input for this formula is the ergodic dynamical system (Ω , G , dP) defining the thermodynamic crystalline phase, where Ω is the configuration space for the atomic degrees of freedom, G is the space group acting on Ω and dP is the ergodic Gibbs measure relative to the G-action. The present work develops an algorithmic method for quantifying (Ω , G , dP) from first principles. Using the silicon crystal as a working example, we find the Gibbs measure to be extremely well characterized by a multivariate normal distribution, which can be quantified using a small number of parameters. The latter are computed at various temperatures and communicated in the form of a table. Using this table, one can generate large and accurate thermally-disordered atomic configurations to serve, for example, as input for subsequent simulations of the electronic degrees of freedom.

Mathematical Optimization Algorithm for Minimizing the Cost Function of GHG Emission in AS/RS Using Positive Selection Based Clonal Selection Principle

NASA Astrophysics Data System (ADS)

Mahalakshmi; Murugesan, R.

2018-04-01

This paper regards with the minimization of total cost of Greenhouse Gas (GHG) efficiency in Automated Storage and Retrieval System (AS/RS). A mathematical model is constructed based on tax cost, penalty cost and discount cost of GHG emission of AS/RS. A two stage algorithm namely positive selection based clonal selection principle (PSBCSP) is used to find the optimal solution of the constructed model. In the first stage positive selection principle is used to reduce the search space of the optimal solution by fixing a threshold value. In the later stage clonal selection principle is used to generate best solutions. The obtained results are compared with other existing algorithms in the literature, which shows that the proposed algorithm yields a better result compared to others.

Temperature-dependent elastic stiffness constants of α- and θ-Al2O3 from first-principles calculations

NASA Astrophysics Data System (ADS)

Shang, Shun-Li; Zhang, Hui; Wang, Yi; Liu, Zi-Kui

2010-09-01

Temperature-dependent elastic stiffness constants (cijs), including both the isothermal and isoentropic ones, have been predicted for rhombohedral α-Al2O3 and monoclinic θ-Al2O3 in terms of a quasistatic approach, i.e., a combination of volume-dependent cijs determined by a first-principles strain versus stress method and direction-dependent thermal expansions obtained by first-principles phonon calculations. A good agreement is observed between the predictions and the available experiments for α-Al2O3, especially for the off-diagonal elastic constants. In addition, the temperature-dependent cijs predicted herein, in particular the ones for metastable θ-Al2O3, enable the stress analysis at elevated temperatures in thermally grown oxides containing α- and θ-Al2O3, which are crucial to understand the failure of thermal barrier coatings in gas-turbine engines.

Experimental and Theoretical Investigations on Viscosity of Fe-Ni-C Liquids at High Pressures

NASA Astrophysics Data System (ADS)

Chen, B.; Lai, X.; Wang, J.; Zhu, F.; Liu, J.; Kono, Y.

2016-12-01

Understanding and modeling of Earth's core processes such as geodynamo and heat flow via convection in liquid outer cores hinges on the viscosity of candidate liquid iron alloys under core conditions. Viscosity estimates from various methods of the metallic liquid of the outer core, however, span up to 12 orders of magnitude. Due to experimental challenges, viscosity measurements of iron liquids alloyed with lighter elements are scarce and conducted at conditions far below those expected for the outer core. In this study, we adopt a synergistic approach by integrating experiments at experimentally-achievable conditions with computations up to core conditions. We performed viscosity measurements based on the modified Stokes' floating sphere viscometry method for the Fe-Ni-C liquids at high pressures in a Paris-Edinburgh press at Sector 16 of the Advanced Photon Source, Argonne National Laboratory. Our results show that the addition of 3-5 wt.% carbon to iron-nickel liquids has negligible effect on its viscosity at pressures lower than 5 GPa. The viscosity of the Fe-Ni-C liquids, however, becomes notably higher and increases by a factor of 3 at 5-8 GPa. Similarly, our first-principles molecular dynamics calculations up to Earth's core pressures show a viscosity change in Fe-Ni-C liquids at 5 GPa. The significant change in the viscosity is likely due to a liquid structural transition of the Fe-Ni-C liquids as revealed by our X-ray diffraction measurements and first-principles molecular dynamics calculations. The observed correlation between structure and physical properties of liquids permit stringent benchmark test of the computational liquid models and contribute to a more comprehensive understanding of liquid properties under high pressures. The interplay between experiments and first-principles based modeling is shown to be a practical and effective methodology for studying liquid properties under outer core conditions that are difficult to reach with the current static high-pressure capabilities. The new viscosity data from experiments and computations would provide new insights into the internal dynamics of the outer core.

Weak photoacoustic signal detection based on the differential duffing oscillator

NASA Astrophysics Data System (ADS)

Li, Chenjing; Xu, Xuemei; Ding, Yipeng; Yin, Linzi; Dou, Beibei

2018-04-01

In view of photoacoustic spectroscopy theory, the relationship between weak photoacoustic signal and gas concentration is described. The studies, on the principle of Duffing oscillator for identifying state transition as well as determining the threshold value, have proven the feasibility of applying the Duffing oscillator in weak signal detection. An improved differential Duffing oscillator is proposed to identify weak signals with any frequency and ameliorate the signal-to-noise ratio. The analytical methods and numerical experiments of the novel model are introduced in detail to confirm its superiority. Then the signal detection system of weak photoacoustic based on differential Duffing oscillator is constructed, it is the first time that the weak signal detection method with differential Duffing oscillator is applied triumphantly in photoacoustic spectroscopy gas monitoring technology.

19 CFR 152.103 - Transaction value.

Code of Federal Regulations, 2010 CFR

2010-04-01

... actually paid or payable will be considered without regard to its method of derivation. It may be the... accounting principles. The method of apportionment actually accepted by Customs will depend upon the... of the first shipment, or (iii) the entire anticipated production. In addition to these three methods...

The Global Optimization of Pt13 Cluster Using the First-Principle Molecular Dynamics with the Quenching Technique

NASA Astrophysics Data System (ADS)

Chen, Xiangping; Duan, Haiming; Cao, Biaobing; Long, Mengqiu

2018-03-01

The high-temperature first-principle molecular dynamics method used to obtain the low energy configurations of clusters [L. L. Wang and D. D. Johnson, PRB 75, 235405 (2007)] is extended to a considerably large temperature range by combination with the quenching technique. Our results show that there are strong correlations between the possibilities for obtaining the ground-state structure and the temperatures. Larger possibilities can be obtained at relatively low temperatures (as corresponds to the pre-melting temperature range). Details of the structural correlation with the temperature are investigated by taking the Pt13 cluster as an example, which suggests a quite efficient method to obtain the lowest-energy geometries of metal clusters.

A vacuum gauge based on an ultracold gas

NASA Astrophysics Data System (ADS)

Makhalov, V. B.; Turlapov, A. V.

2017-06-01

We report the design and application of a primary vacuum gauge based on an ultracold gas of atoms in an optical dipole trap. The pressure is calculated from the confinement time for atoms in the trap. The relationship between pressure and confinement time is established from the first principles owing to elimination of all channels introducing losses, except for knocking out an atom from the trap due to collisions with a residual gas particle. The method requires the knowledge of the gas chemical composition in the vacuum chamber, and, in the absence of this information, the systematic error is less than that of the ionisation sensor.

A “good death”: perspectives of Muslim patients and health care providers

PubMed Central

Tayeb, Mohamad A.; Al-Zamel, Ersan; Fareed, Muhammed M.; Abouellail, Hesham A.

2010-01-01

BACKGROUND AND OBJECTIVES: Twelve “good death” principles have been identified that apply to Westerners. This study aimed to review the TFHCOP good death perception to determine its validity for Muslim patients and health care providers, and to identify and describe other components of the Muslim good death perspective. SUBJECTS AND METHODS: Participants included 284 Muslims of both genders with different nationalities and careers. We used a 12-question questionnaire based on the 12 principles of the TFHCOP good death definition, followed by face-to-face interviews. We used descriptive statistics to analyze questionnaire responses. However, for new themes, we used a grounded theory approach with a “constant comparisons” method. RESULT: On average, each participant agreed on eight principles of the questionnaire. Dignity, privacy, spiritual and emotional support, access to hospice care, ability to issue advance directives, and to have time to say goodbye were the top priorities. Participants identified three main domains. The first domain was related to faith and belief. The second domain included some principles related to self-esteem and person>s image to friends and family. The third domain was related to satisfaction about family security after the death of the patient. Professional role distinctions were more pronounced than were gender or nationality differences. CONCLUSION: Several aspects of «good death,» as perceived by Western communities, are not recognized as being important by many Muslim patients and health care providers. Furthermore, our study introduced three novel components of good death in Muslim society. PMID:20427938

Extension to linear dynamics for hybrid stress finite element formulation based on additional displacements

NASA Astrophysics Data System (ADS)

Sumihara, K.

Based upon legitimate variational principles, one microscopic-macroscopic finite element formulation for linear dynamics is presented by Hybrid Stress Finite Element Method. The microscopic application of Geometric Perturbation introduced by Pian and the introduction of infinitesimal limit core element (Baby Element) have been consistently combined according to the flexible and inherent interpretation of the legitimate variational principles initially originated by Pian and Tong. The conceptual development based upon Hybrid Finite Element Method is extended to linear dynamics with the introduction of physically meaningful higher modes.

Extrinsic spin Nernst effect from first principles.

PubMed

Tauber, Katarina; Gradhand, Martin; Fedorov, Dmitry V; Mertig, Ingrid

2012-07-13

We present an ab initio description of the thermal transport phenomenon called the spin Nernst effect. It refers to generation of a spin accumulation or a pure spin current transverse to an applied temperature gradient. This is similar to the intensively studied spin Hall effect described by intrinsic and extrinsic mechanisms due to an applied electric field. Analogously, several contributions are present for the spin Nernst effect. Here we investigate the extrinsic skew scattering mechanism which is dominant in the limit of dilute alloys. Our calculations are based on a fully relativistic Korringa-Kohn-Rostoker method and a solution of the linearized Boltzmann equation. As a first application, we consider a Cu host with Au, Ti, and Bi impurities.

Stability of vacancy-type defect clusters in Ni based on first-principles and molecular dynamics simulations

DOE PAGES

Zhao, Shijun; Zhang, Yanwen; Weber, William J.

2017-10-17

Using first-principles calculations based on density-functional theory, the energetics of different vacancy-type defects, including voids, stacking fault tetrahedra (SFT) and vacancy loops, in Ni are investigated. It is found that voids are more stable than SFT at 0 K, which is also the case after taking into account the volumetric strains. By carrying out ab initio molecular dynamics simulations at temperatures up to 1000 K, direct transformations from vacancy loops and voids into SFT are observed. Our results suggest the importance of temperature effects in determining thermodynamic stability of vacancy clusters in face-centered cubic metals.

Gas adsorption in Mg-porphyrin-based porous organic frameworks: A computational simulation by first-principles derived force field.

PubMed

Pang, Yujia; Li, Wenliang; Zhang, Jingping

2017-09-15

A novel type of porous organic frameworks, based on Mg-porphyrin, with diamond-like topology, named POF-Mgs is computationally designed, and the gas uptakes of CO 2 , H 2 , N 2 , and H 2 O in POF-Mgs are investigated by Grand canonical Monte Carlo simulations based on first-principles derived force fields (FF). The FF, which describes the interactions between POF-Mgs and gases, are fitted by dispersion corrected double-hybrid density functional theory, B2PLYP-D3. The good agreement between the obtained FF and the first-principle energies data confirms the reliability of the FF. Furthermore our simulation shows the presence of a small amount of H 2 O (≤ 0.01 kPa) does not much affect the adsorption quantity of CO 2 , but the presence of higher partial pressure of H 2 O (≥ 0.1 kPa) results in the CO 2 adsorption decrease significantly. The good performance of POF-Mgs in the simulation inspires us to design novel porous materials experimentally for gas adsorption and purification. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The interaction between cations and anionic groups inducing SHG enhancement in a series of apatite-like crystals: A first-principles study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jing, Qun; University of Chinese Academy of Sciences, Beijing 100049; Department of Physics, School of Science, Shihezi University, Shihezi 832000

2014-11-15

It is an interesting topic to reveal the origin of the SHG intensity enhancement after substitution from alkali and alkali-earth metal atoms to cadmium in a series of apatite-like borates KSr{sub 4}(BO{sub 3}){sub 3}, Ca{sub 5}(BO{sub 3}){sub 3}F, Cd{sub 5}(BO{sub 3}){sub 3}F. Combined with the first-principles method, SHG-density method and real-space atom-cutting method, the electronic structure, the optical properties and the contribution of respective ion and ion groups have been investigated. Second harmonic generation (SHG) responses are mainly attributed to BO{sub 3} groups with π conjugated configuration and their alignment framework. The contributions of A site are more important inmore » CaBOF and CdBOF compounds than in KSrBO. It is also demonstrated that the strong covalent interactions between the boron–oxygen groups and the cadmium atoms contribute the enhancement of SHG responses after substitution from alkali and alkali-earth metal atoms. - graphical abstract: Combined with the first-principles method, SHG-density method and real-space atom-cutting method, the enhancement of SHG response are attributed to the interaction between cadmium and BO{sub 3} groups. - Highlights: • SHG response on a series of apatite-like borates was studied by a SHG-density method. • SHG responses are mainly attributed to BO{sub 3} groups and their alignment framework. • The contributions of A site are more important in CaBOF and CdBOF than in KSrBO. • Covalent interaction between BO and Cd is responsible for SHG of CdBOF.« less

Crystal structure of Earth's inner core: A first-principles study

NASA Astrophysics Data System (ADS)

Moustafa, S. G.; Schultz, A. J.; Zurek, E.; Kofke, D. A.

2017-12-01

Since the detection of the Earth's solid inner core (IC) by Lehmann in 1936, its composition and crystal structure (which are essential to understand Earth's evolution) have been controversial. While seismological measurements (e.g. PREM) can give a robust estimation of the density, pressure, and elasticity of the IC, they cannot be directly used to determine its composition and/or crystal structure. Experimentally, reaching the extreme IC conditions ( 330 GPa and 6000 K) and getting reliable measurements is very challenging. First-principles calculations provide a viable alternative that can work as a powerful investigative tool. Although several attempts have been made to assess phase stability at IC conditions computationally, they often use a low level of theory for electronic structure (e.g., classical force-field), adopt approximate methods (e.g., quasiharmonic approximation, fixed hcp-c/a), or do not consider finite-size effects. The study of phase stability using accurate first-principles methods is hampered in part by the difficulty of computing the free energy (FE), the central thermodynamic quantity that determines stability, while including anharmonic and finite-size effects. Additional difficulty related to the IC in particular is introduced by the dynamical instability of one of the IC candidate structures (bcc) at low temperature. Recently [1-3], we introduced a novel method (denoted as "harmonically mapped averaging", or HMA) to efficiently measure anharmonic properties (e.g. FE, pressure, elastic modulus) by molecular simulation, yielding orders of magnitude CPU speedup compared to conventional methods. We have applied this method to the hcp candidate phase of iron at the IC conditions, obtaining first-principles anharmonic FE values with unprecedented accuracy and precision [4]. We have now completed and report HMA calculations to assess the phase stability of all IC candidate phases (fcc/hcp/bcc). This knowledge is the prerequisite for interpreting the geophysical and geochemical constraints of the IC (e.g. anisotropy and low rigidity); which should be a key ingredient in the longstanding debate about the nature of the Earth's IC. References[1] 10.1103/PhysRevE.92.043303[2] 10.1021/acs.jctc.6b00018[3] 10.1021/acs.jctc.6b01082[4] 10.1103/PhysRevB.96.014117

Optical properties of LiGaS2: an ab initio study and spectroscopic ellipsometry measurement

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Lin, Z. S.; Isaenko, L. I.; Kesler, V. G.; Kruchinin, V. N.; Lobanov, S. I.

2009-11-01

Electronic and optical properties of lithium thiogallate crystal, LiGaS2, have been investigated by both experimental and theoretical methods. The plane-wave pseudopotential method based on DFT theory has been used for band structure calculations. The electronic parameters of Ga 3d orbitals have been corrected by the DFT+U methods to be consistent with those measured with x-ray photoemission spectroscopy. Evolution of optical constants of LiGaS2 over a wide spectral range was determined by developed first-principles theory and dispersion curves were compared with optical parameters defined by spectroscopic ellipsometry in the photon energy range 1.2-5.0 eV. Good agreement has been achieved between theoretical and experimental results.

Semantic Information Extraction of Lanes Based on Onboard Camera Videos

NASA Astrophysics Data System (ADS)

Tang, L.; Deng, T.; Ren, C.

2018-04-01

In the field of autonomous driving, semantic information of lanes is very important. This paper proposes a method of automatic detection of lanes and extraction of semantic information from onboard camera videos. The proposed method firstly detects the edges of lanes by the grayscale gradient direction, and improves the Probabilistic Hough transform to fit them; then, it uses the vanishing point principle to calculate the lane geometrical position, and uses lane characteristics to extract lane semantic information by the classification of decision trees. In the experiment, 216 road video images captured by a camera mounted onboard a moving vehicle were used to detect lanes and extract lane semantic information. The results show that the proposed method can accurately identify lane semantics from video images.

Convex Accelerated Maximum Entropy Reconstruction

PubMed Central

Worley, Bradley

2016-01-01

Maximum entropy (MaxEnt) spectral reconstruction methods provide a powerful framework for spectral estimation of nonuniformly sampled datasets. Many methods exist within this framework, usually defined based on the magnitude of a Lagrange multiplier in the MaxEnt objective function. An algorithm is presented here that utilizes accelerated first-order convex optimization techniques to rapidly and reliably reconstruct nonuniformly sampled NMR datasets using the principle of maximum entropy. This algorithm – called CAMERA for Convex Accelerated Maximum Entropy Reconstruction Algorithm – is a new approach to spectral reconstruction that exhibits fast, tunable convergence in both constant-aim and constant-lambda modes. A high-performance, open source NMR data processing tool is described that implements CAMERA, and brief comparisons to existing reconstruction methods are made on several example spectra. PMID:26894476

An efficient method for quantum transport simulations in the time domain

NASA Astrophysics Data System (ADS)

Wang, Y.; Yam, C.-Y.; Frauenheim, Th.; Chen, G. H.; Niehaus, T. A.

2011-11-01

An approximate method based on adiabatic time dependent density functional theory (TDDFT) is presented, that allows for the description of the electron dynamics in nanoscale junctions under arbitrary time dependent external potentials. The density matrix of the device region is propagated according to the Liouville-von Neumann equation. The semi-infinite leads give rise to dissipative terms in the equation of motion which are calculated from first principles in the wide band limit. In contrast to earlier ab initio implementations of this formalism, the Hamiltonian is here approximated in the spirit of the density functional based tight-binding (DFTB) method. Results are presented for two prototypical molecular devices and compared to full TDDFT calculations. The temporal profile of the current traces is qualitatively well captured by the DFTB scheme. Steady state currents show considerable variations, both in comparison of approximate and full TDDFT, but also among TDDFT calculations with different basis sets.

Concave omnidirectional imaging device for cylindrical object based on catadioptric panoramic imaging

NASA Astrophysics Data System (ADS)

Wu, Xiaojun; Wu, Yumei; Wen, Peizhi

2018-03-01

To obtain information on the outer surface of a cylinder object, we propose a catadioptric panoramic imaging system based on the principle of uniform spatial resolution for vertical scenes. First, the influence of the projection-equation coefficients on the spatial resolution and astigmatism of the panoramic system are discussed, respectively. Through parameter optimization, we obtain the appropriate coefficients for the projection equation, and so the imaging quality of the entire imaging system can reach an optimum value. Finally, the system projection equation is calibrated, and an undistorted rectangular panoramic image is obtained using the cylindrical-surface projection expansion method. The proposed 360-deg panoramic-imaging device overcomes the shortcomings of existing surface panoramic-imaging methods, and it has the advantages of low cost, simple structure, high imaging quality, and small distortion, etc. The experimental results show the effectiveness of the proposed method.

A Hybrid Wavelet-Based Method for the Peak Detection of Photoplethysmography Signals.

PubMed

Li, Suyi; Jiang, Shanqing; Jiang, Shan; Wu, Jiang; Xiong, Wenji; Diao, Shu

2017-01-01

The noninvasive peripheral oxygen saturation (SpO 2 ) and the pulse rate can be extracted from photoplethysmography (PPG) signals. However, the accuracy of the extraction is directly affected by the quality of the signal obtained and the peak of the signal identified; therefore, a hybrid wavelet-based method is proposed in this study. Firstly, we suppressed the partial motion artifacts and corrected the baseline drift by using a wavelet method based on the principle of wavelet multiresolution. And then, we designed a quadratic spline wavelet modulus maximum algorithm to identify the PPG peaks automatically. To evaluate this hybrid method, a reflective pulse oximeter was used to acquire ten subjects' PPG signals under sitting, raising hand, and gently walking postures, and the peak recognition results on the raw signal and on the corrected signal were compared, respectively. The results showed that the hybrid method not only corrected the morphologies of the signal well but also optimized the peaks identification quality, subsequently elevating the measurement accuracy of SpO 2 and the pulse rate. As a result, our hybrid wavelet-based method profoundly optimized the evaluation of respiratory function and heart rate variability analysis.

A Hybrid Wavelet-Based Method for the Peak Detection of Photoplethysmography Signals

PubMed Central

Jiang, Shanqing; Jiang, Shan; Wu, Jiang; Xiong, Wenji

2017-01-01

The noninvasive peripheral oxygen saturation (SpO2) and the pulse rate can be extracted from photoplethysmography (PPG) signals. However, the accuracy of the extraction is directly affected by the quality of the signal obtained and the peak of the signal identified; therefore, a hybrid wavelet-based method is proposed in this study. Firstly, we suppressed the partial motion artifacts and corrected the baseline drift by using a wavelet method based on the principle of wavelet multiresolution. And then, we designed a quadratic spline wavelet modulus maximum algorithm to identify the PPG peaks automatically. To evaluate this hybrid method, a reflective pulse oximeter was used to acquire ten subjects' PPG signals under sitting, raising hand, and gently walking postures, and the peak recognition results on the raw signal and on the corrected signal were compared, respectively. The results showed that the hybrid method not only corrected the morphologies of the signal well but also optimized the peaks identification quality, subsequently elevating the measurement accuracy of SpO2 and the pulse rate. As a result, our hybrid wavelet-based method profoundly optimized the evaluation of respiratory function and heart rate variability analysis. PMID:29250135

Achieving accuracy in first-principles calculations at extreme temperature and pressure

NASA Astrophysics Data System (ADS)

Mattsson, Ann; Wills, John

2013-06-01

First-principles calculations are increasingly used to provide EOS data at pressures and temperatures where experimental data is difficult or impossible to obtain. The lack of experimental data, however, also precludes validation of the calculations in those regimes. Factors influencing the accuracy of first-principles data include theoretical approximations, and computational approximations used in implementing and solving the underlying equations. The first category includes approximate exchange-correlation functionals and wave equations simplifying the Dirac equation. In the second category are, e.g., basis completeness and pseudo-potentials. While the first category is extremely hard to assess without experimental data, inaccuracies of the second type should be well controlled. We are using two rather different electronic structure methods (VASP and RSPt) to make explicit the requirements for accuracy of the second type. We will discuss the VASP Projector Augmented Wave potentials, with examples for Li and Mo. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Isolation and purification of rabbit mesenchymal stem cells using an optimized protocol.

PubMed

Lin, Chunbo; Shen, Maorong; Chen, Weiping; Li, Xiaofeng; Luo, Daoming; Cai, Jinhong; Yang, Yuan

2015-11-01

Mesenchymal stem cells were first isolated and grown in vitro by Friedenstein over 40 yr ago; however, their isolation remains challenging as they lack unique markers for identification and are present in very small quantities in mesenchymal tissues and bone marrow. Using whole marrow samples, common methods for mesenchymal stem cell isolation are the adhesion method and density gradient fractionation. The whole marrow sample adhesion method still results in the nonspecific isolation of mononuclear cells, and activation and/or potential loss of target cells. Density gradient fractionation methods are complicated, and may result in contamination with toxic substances that affect cell viability. In the present study, we developed an optimized protocol for the isolation and purification of mesenchymal stem cells based on the principles of hypotonic lysis and natural sedimentation.

Homogeneity study of fixed-point continuous marine environmental and meteorological data: a review

NASA Astrophysics Data System (ADS)

Yang, Jinkun; Yang, Yang; Miao, Qingsheng; Dong, Mingmei; Wan, Fangfang

2018-02-01

The principle of inhomogeneity and the classification of homogeneity test methods are briefly described, and several common inhomogeneity methods and relative merits are described in detail. Then based on the applications of the different homogeneity methods to the ground meteorological data and marine environment data, the present status and the progress are reviewed. At present, the homogeneity research of radiosonde and ground meteorological data is mature at home and abroad, and the research and application in the marine environmental data should also be given full attention. To carry out a variety of test and correction methods combined with the use of multi-mode test system, will make the results more reasonable and scientific, and also can be used to provide accurate first-hand information for the coastal climate change researches.

Extraction of information on macromolecular interactions from fluorescence micro-spectroscopy measurements in the presence and absence of FRET.

PubMed

Raicu, Valerică

2018-06-15

Investigations of static or dynamic interactions between proteins or other biological macromolecules in living cells often rely on the use of fluorescent tags with two different colors in conjunction with adequate theoretical descriptions of Förster Resonance Energy Transfer (FRET) and molecular-level micro-spectroscopic technology. One such method based on these general principles is FRET spectrometry, which allows determination of the quaternary structure of biomolecules from cell-level images of the distributions, or spectra of occurrence frequency of FRET efficiencies. Subsequent refinements allowed combining FRET frequency spectra with molecular concentration information, thereby providing the proportion of molecular complexes with various quaternary structures as well as their binding/dissociation energies. In this paper, we build on the mathematical principles underlying FRET spectrometry to propose two new spectrometric methods, which have distinct advantages compared to other methods. One of these methods relies on statistical analysis of color mixing in subpopulations of fluorescently tagged molecules to probe molecular association stoichiometry, while the other exploits the color shift induced by FRET to also derive geometric information in addition to stoichiometry. The appeal of the first method stems from its sheer simplicity, while the strength of the second consists in its ability to provide structural information. Copyright © 2018 Elsevier B.V. All rights reserved.

Extraction of information on macromolecular interactions from fluorescence micro-spectroscopy measurements in the presence and absence of FRET

NASA Astrophysics Data System (ADS)

Raicu, Valerică

2018-06-01

Investigations of static or dynamic interactions between proteins or other biological macromolecules in living cells often rely on the use of fluorescent tags with two different colors in conjunction with adequate theoretical descriptions of Förster Resonance Energy Transfer (FRET) and molecular-level micro-spectroscopic technology. One such method based on these general principles is FRET spectrometry, which allows determination of the quaternary structure of biomolecules from cell-level images of the distributions, or spectra of occurrence frequency of FRET efficiencies. Subsequent refinements allowed combining FRET frequency spectra with molecular concentration information, thereby providing the proportion of molecular complexes with various quaternary structures as well as their binding/dissociation energies. In this paper, we build on the mathematical principles underlying FRET spectrometry to propose two new spectrometric methods, which have distinct advantages compared to other methods. One of these methods relies on statistical analysis of color mixing in subpopulations of fluorescently tagged molecules to probe molecular association stoichiometry, while the other exploits the color shift induced by FRET to also derive geometric information in addition to stoichiometry. The appeal of the first method stems from its sheer simplicity, while the strength of the second consists in its ability to provide structural information.

Investigation of structural stability and elastic properties of CrH and MnH: A first principles study

NASA Astrophysics Data System (ADS)

Kanagaprabha, S.; Rajeswarapalanichamy, R.; Sudhapriyanga, G.; Murugan, A.; Santhosh, M.; Iyakutti, K.

2015-06-01

The structural and mechanical properties of CrH and MnH are investigated using first principles calculation based on density functional theory as implemented in VASP code with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and other theoretical results. A structural phase transition from NaCl to NiAs phase at a pressure of 76 GPa is predicted for both CrH and MnH.

Origin of Spinel Nanocheckerboards via First Principles

NASA Astrophysics Data System (ADS)

Kornbluth, Mordechai; Marianetti, Chris A.

2015-06-01

Self-organizing nanocheckerboards have been experimentally fabricated in Mn-based spinels but have not yet been explained with first principles. Using density-functional theory, we explain the phase diagram of the ZnMnxGa2 -xO4 system and the origin of nanocheckerboards. We predict total phase separation at zero temperature and then show the combination of kinetics, thermodynamics, and Jahn-Teller physics that generates the system's observed behavior. We find that the {011 } surfaces are strongly preferred energetically, which mandates checkerboard ordering by purely geometrical considerations.

Electronic structure and microscopic model of CoNb2O6

NASA Astrophysics Data System (ADS)

Molla, Kaimujjaman; Rahaman, Badiur

2018-05-01

We present the first principle density functional calculations to figure out the underlying spin model of CoNb2O6. The first principles calculations define the main paths of superexchange interaction between Co spins in this compound. We discuss the nature of the exchange paths and provide quantitative estimates of magnetic exchange couplings. A microscopic modeling based on analysis of the electronic structure of this system puts it in the interesting class of weakly couple geometrically frustrated isosceles triangular Ising antiferromagnet.

[A research in speech endpoint detection based on boxes-coupling generalization dimension].

PubMed

Wang, Zimei; Yang, Cuirong; Wu, Wei; Fan, Yingle

2008-06-01

In this paper, a new calculating method of generalized dimension, based on boxes-coupling principle, is proposed to overcome the edge effects and to improve the capability of the speech endpoint detection which is based on the original calculating method of generalized dimension. This new method has been applied to speech endpoint detection. Firstly, the length of overlapping border was determined, and through calculating the generalized dimension by covering the speech signal with overlapped boxes, three-dimension feature vectors including the box dimension, the information dimension and the correlation dimension were obtained. Secondly, in the light of the relation between feature distance and similarity degree, feature extraction was conducted by use of common distance. Lastly, bi-threshold method was used to classify the speech signals. The results of experiment indicated that, by comparison with the original generalized dimension (OGD) and the spectral entropy (SE) algorithm, the proposed method is more robust and effective for detecting the speech signals which contain different kinds of noise in different signal noise ratio (SNR), especially in low SNR.

Computational Methods to Predict Protein Interaction Partners

NASA Astrophysics Data System (ADS)

Valencia, Alfonso; Pazos, Florencio

In the new paradigm for studying biological phenomena represented by Systems Biology, cellular components are not considered in isolation but as forming complex networks of relationships. Protein interaction networks are among the first objects studied from this new point of view. Deciphering the interactome (the whole network of interactions for a given proteome) has been shown to be a very complex task. Computational techniques for detecting protein interactions have become standard tools for dealing with this problem, helping and complementing their experimental counterparts. Most of these techniques use genomic or sequence features intuitively related with protein interactions and are based on "first principles" in the sense that they do not involve training with examples. There are also other computational techniques that use other sources of information (i.e. structural information or even experimental data) or are based on training with examples.

Lattice thermal conductivity of monolayer AsP from first-principles molecular dynamics.

PubMed

Sun, Yajing; Shuai, Zhigang; Wang, Dong

2018-05-23

Few-layered arsenic-phosphorus alloys, AsxP(1-x), with a puckered structure have been recently synthesized and demonstrated with fully tunable band gaps and optical properties. It is predicted that the carrier mobility of monolayer AsP compounds is even higher than that of black phosphorene (b-P). The anisotropic and orthogonal electrical and thermal transport properties of the puckered group VA elements make them intriguing materials for thermoelectric applications. Herein, we investigated the thermal transport properties of AsP based on first-principles molecular dynamics and the Boltzmann transport equation. We reveal that monolayer AsP with three different chemical structures possesses thermal conductivities lower than b-P, but with increased anisotropy. Further, these structures behave profoundly different on heat conduction. This can be attributed to the distinct low-frequency optical modes associated with their bonding nature. Our results highlight the impact of atomic arrangement on the thermal conductivity of AsP, and the structure-property relationship established may guide the fabrication of thermoelectric materials via the engineered alloying method.

Zn(x)Cd(1-x)Se nanomultipods with tunable band gaps: synthesis and first-principles calculations.

PubMed

Wei, Hao; Su, Yanjie; Han, Ziyi; Li, Tongtong; Ren, Xinglong; Yang, Zhi; Wei, Liangming; Cong, Fengsong; Zhang, Yafei

2013-06-14

In this paper, we demonstrate that ZnxCd1-xSe nanomultipods can be synthesized via a facile and nontoxic solution-based method. Interesting aspects of composition, morphology and optical properties were deeply explored. The value of Zn/(Zn+Cd) could be altered across the entire range from 0.08 to 0.86 by varying the ratio of cation precursor contents. The band gap energy could be linearly tuned from 1.88 to 2.48 eV with respect to the value of Zn/(Zn+Cd). The experiment also showed that oleylamine played a dominant role in the formation of multipod structure. A possible growth mechanism was further suggested. First-principles calculations of band gap energy and density of states in the Vienna ab initio simulation package code were performed to verify the experimental variation tendency of the band gap. Computational results indicated that dissimilarities of electronic band structures and orbital constitutions determined the tunable band gap of the as-synthesized nanomultipod, which might be promising for versatile applications in relevant areas of solar cells, biomedicine, sensors, catalysts and so on.

First-principles investigation of the structural characteristics of LiMO2 cathode materials for lithium secondary batteries

NASA Astrophysics Data System (ADS)

Kim, Yongseon

2015-11-01

The structural features related to the defects of LiMO2 (M = Ni, Co, Mn) cathode materials for lithium secondary batteries were investigated by a simulation of phase diagrams based on first-principle calculations. Crystal models with various types of point defects were designed and dealt with as independent phases, which enabled an examination of the thermodynamic stability of the defects. A perfect phase without defects appeared to be the most stable for LiCoO2, whereas the formation of Li vacancies, O vacancies, and antisites between Li and Ni was thermodynamically unavoidable for LiNiO2. The introduction of both Co and Mn in LiNiO2 was effective in reducing the formation of point defects, but increasing the relative amount of Mn was undesirable because the antisite defect remained stable with Mn doping. The simulation showed good agreement with the experimental data and previous reports. Therefore, the method and the results of this study are expected to be useful for examining the synthesis, structure and related properties of layer-structured cathode materials.

Shear-strain gradient induced polarization reversal in ferroelectric BaTiO3 thin films: A first-principles total-energy study

NASA Astrophysics Data System (ADS)

Li, Guannan; Huang, Xiaokun; Hu, Jingsan; Zhang, Weiyi

2017-04-01

Based on the first-principles total-energy calculation, we have studied the shear-strain gradient effect on the polarization reversal of ferroelectric BaTiO3 thin films. By calculating the energies of double-domain supercells for different electric polarization, shear-strain gradients, and domain-wall displacement, we extracted, in addition to the domain-wall energy, the polarization energy, elastic energy, and flexoelectric coefficient of a single domain. The constructed Landau-Devonshire phenomenological theory yields a critical shear-strain gradient of 9.091 ×107/m (or a curvature radius (R ) of 110 Å) for reversing the 180∘ domain at room temperature, which is on the same order of the experimentally estimated value of 3.333 ×107/m (R =300 Å ). In contrast to the commonly used linear response theory, the flexoelectric coefficient derived from fitting the total energy to a Landau-Devonshire energy functional does not depend on the specific pseudopotential. Thus, our method offers an alternative numerical approach to study the flexoelectric effect.

Research progress in Asia on methods of processing laser-induced breakdown spectroscopy data

NASA Astrophysics Data System (ADS)

Guo, Yang-Min; Guo, Lian-Bo; Li, Jia-Ming; Liu, Hong-Di; Zhu, Zhi-Hao; Li, Xiang-You; Lu, Yong-Feng; Zeng, Xiao-Yan

2016-10-01

Laser-induced breakdown spectroscopy (LIBS) has attracted much attention in terms of both scientific research and industrial application. An important branch of LIBS research in Asia, the development of data processing methods for LIBS, is reviewed. First, the basic principle of LIBS and the characteristics of spectral data are briefly introduced. Next, two aspects of research on and problems with data processing methods are described: i) the basic principles of data preprocessing methods are elaborated in detail on the basis of the characteristics of spectral data; ii) the performance of data analysis methods in qualitative and quantitative analysis of LIBS is described. Finally, a direction for future development of data processing methods for LIBS is also proposed.

A Rationality Standard for the First Amendment.

ERIC Educational Resources Information Center

Rohrer, Daniel M.

This discussion summarizes the general principles that may be applied in determining the limits of free expression and proposes new criteria based on libertarian values. Among the general principles summarized are the bad-tendency test, the clear-and-present-danger test, the balancing test, the incitement test, and the hypothetical absolute test.…

Does the Modality Principle for Multimedia Learning Apply to Science Classrooms?

ERIC Educational Resources Information Center

Harskamp, Egbert G.; Mayer, Richard E.; Suhre, Cor

2007-01-01

This study demonstrated that the modality principle applies to multimedia learning of regular science lessons in school settings. In the first field experiment, 27 Dutch secondary school students (age 16-17) received a self-paced, web-based multimedia lesson in biology. Students who received lessons containing illustrations and narration performed…

THE PSYCHOBIOLOGICAL INVESTIGATION OF THE DEVELOPMENT OF NEW VERBAL BEHAVIOR. FINAL TECHNICAL REPORT.

ERIC Educational Resources Information Center

FERSTER, C.B.

THESE EXPERIMENTS WITH VERBAL BEHAVIOR WERE CARRIED OUT AS AN EXTENSION AND ADAPTATION OF GENERAL LABORATORY PRINCIPLES DEVELOPED WITH ANIMALS. THE EXPERIMENTS COVERED THREE AREAS. THE FIRST WAS AN APPLICATION OF GENERAL PRINCIPLES OF VERBAL BEHAVIOR, LARGELY BASED ON SKINNER'S ANALYSIS, TO THE PROBLEMS OF TEACHING A SECOND LANGUAGE. ACTUAL…

Framework for Asynchronous Discussion Design Decisions: Applied Principles from Special Issue Authors

ERIC Educational Resources Information Center

Grabowski, Barbara L.

2011-01-01

After a discussion of the state of both misaligned and informative online and distance education research, the authors in this special issue (hereafter called the collective) extract evidence-based principles about strategies that work. Both are addressed in this article. First, their criticisms centered on the value of comparative research. Those…

Toward a Comprehensive Model of Antisocial Development: A Dynamic Systems Approach

ERIC Educational Resources Information Center

Granic, Isabela; Patterson, Gerald R.

2006-01-01

The purpose of this article is to develop a preliminary comprehensive model of antisocial development based on dynamic systems principles. The model is built on the foundations of behavioral research on coercion theory. First, the authors focus on the principles of multistability, feedback, and nonlinear causality to reconceptualize real-time…

Using a Principle-Based Method to Support a Disability Aesthetic

ERIC Educational Resources Information Center

Anderson, Bailey

2015-01-01

This article calls choreographers and educators alike to continue building an awareness of methodologies that support a disability aesthetic. A disability aesthetic supports the embodiment of dancers with disabilities by allowing for their bodies to set guidelines of beauty and value. Principle-based work is a methodology that supports a…

An Educational Development Tool Based on Principles of Formal Ontology

ERIC Educational Resources Information Center

Guzzi, Rodolfo; Scarpanti, Stefano; Ballista, Giovanni; Di Nicolantonio, Walter

2005-01-01

Computer science provides with virtual laboratories, places where one can merge real experiments with the formalism of algorithms and mathematics and where, with the advent of multimedia, sounds and movies can also be added. In this paper we present a method, based on principles of formal ontology, allowing one to develop interactive educational…

Introspective Reasoning Models for Multistrategy Case-Based and Explanation

DTIC Science & Technology

1997-03-10

symptoms and diseases to causal 30 principles about diseases and first-principle analysis grounded in basic science. Based on research in process...the symptoms of the failure to conclusion that the process which posts learning goals a causal explanation of the failure. Secondl,,. the learner...the vernacular, a "jones" is a drug habit accompanied the faucet for water. Therefore, the story can end with by withdrawal symptoms . The verb "to jones

Use of Fructosyl Peptide Oxidase for HbA1c Assay

PubMed Central

Yonehara, Satoshi; Inamura, Norio; Fukuda, Miho; Sugiyama, Koji

2015-01-01

ARKRAY, Inc developed the world’s first automatic glycohemoglobin analyzer based on HPLC (1981). After that, ARKRAY developed enzymatic HbA1c assay “CinQ HbA1c” with the spread and diversification of HbA1c measurement (2007). CinQ HbA1c is the kit of Clinical Chemistry Analyzer, which uses fructosyl peptide oxidase (FPOX) for a measurement reaction. This report mainly indicates the developmental background, measurement principle, and future of the enzymatic method HbA1c reagent. PMID:25633966

First-principles Theory of Inelastic Transport and Local Heating in Atomic Gold Wires

NASA Astrophysics Data System (ADS)

Frederiksen, Thomas; Paulsson, Magnus; Brandbyge, Mads; Jauho, Antti-Pekka

2007-04-01

We present theoretical calculations of the inelastic transport properties in atomic gold wires. Our method is based on a combination of density functional theory and non-equilibrium Green's functions. The vibrational spectra for extensive series of wire geometries have been calculated using SIESTA, and the corresponding effects in the conductance are analyzed. In particular, we focus on the heating of the active vibrational modes. By a detailed comparison with experiments we are able to estimate an order of magnitude for the external damping of the active vibrations.

Transition-metal alloying of γ'-Ni3Al : Effects on the ideal uniaxial compressive strength from first-principles calculations

NASA Astrophysics Data System (ADS)

Wen, Minru; Wang, Chong-Yu

2018-01-01

The addition of transition-metal (TM) elements into the γ' precipitate phase of a Ni-based single-crystal superalloy can significantly affect its mechanical properties, including the intrinsic mechanical property of compressive strength. Using first-principles density functional calculations, the effects of 3 d (Sc-Zn), 4 d (Y-Cd), and 5 d (Hf-Au) TM alloying elements on the ideal uniaxial compressive strength of γ'-Ni3Al were investigated. The stress-strain relationships of pure Ni3Al under [100], [110], and [111] compressive loads and the site occupancy behavior of TM elements in Ni3Al were previously studied using a total-energy method based on density functional theory. Our results showed that the capacity of TM elements for strengthening the ideal compressive strength was associated with the d -electron number. The alloying elements with half-filled d bands (i.e., Cr, Mo, W, Tc, and Re) manifested the greatest efficacy for improving the ideal strength of Ni3Al under a deformation along the weakest compressive direction. Furthermore, the charge redistribution of Ni3Al doped with 5 d elements were also analyzed to understand the strengthening mechanisms of TM elements in the γ'-Ni3Al phase.

Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R. L.; Damewood, L.; Zeng, Y. J.

To search for half-metallic materials for spintronic applications, instead of using an expensive trial-and-error experimental scheme, it is more efficient to use first-principles calculations to design materials first, and then grow them. In particular, using a priori information of the structural stability and the effect of the spin–orbit interaction (SOI) enables experimentalists to focus on favorable properties that make growing half-metals easier. We suggest that using acoustic phonon spectra is the best way to address the stability of promising half-metallic materials. Additionally, by carrying out accurate first-principles calculations, we propose two criteria for neglecting the SOI so the half-metallicity persists.more » As a result, based on the mechanical stability and the negligible SOI, we identified two half-metals, β-LiCrAs and β-LiMnSi, as promising half-Heusler alloys worth growing.« less

Did Ptolemy understand the moon illusion?

PubMed

Ross, H E; Ross, G M

1976-01-01

Ptolemy is often wrongly credited with an explanation of the moon illusion based on the size-distance invariance principle. This paper elucidates the two Ptolemaic accounts: one in the Almagest, based on atmospheric refraction, and the other in the Optics, based on the difficulty of looking upwards. It is the latter passage which has been thought to refer to size-distance invariance, but it is more probable that it refers to the idea that the visual rays are diminished by the force of gravity (i.e. that the retinal image is reduced in size). Alhazen was probably the first author to explain the illusion by the size-distance invariance principle, and Roger Bacon the first to explain the enlarged apparent distance of the horizon by the presence of intervening objects. Della Porta was the first to credit Ptolemy with these explanations, and this mistake was repeated by many subsequent authors.

Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect

DOE PAGES

Zhang, R. L.; Damewood, L.; Zeng, Y. J.; ...

2017-07-07

To search for half-metallic materials for spintronic applications, instead of using an expensive trial-and-error experimental scheme, it is more efficient to use first-principles calculations to design materials first, and then grow them. In particular, using a priori information of the structural stability and the effect of the spin–orbit interaction (SOI) enables experimentalists to focus on favorable properties that make growing half-metals easier. We suggest that using acoustic phonon spectra is the best way to address the stability of promising half-metallic materials. Additionally, by carrying out accurate first-principles calculations, we propose two criteria for neglecting the SOI so the half-metallicity persists.more » As a result, based on the mechanical stability and the negligible SOI, we identified two half-metals, β-LiCrAs and β-LiMnSi, as promising half-Heusler alloys worth growing.« less

Comparison of chiller models for use in model-based fault detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sreedharan, Priya; Haves, Philip

Selecting the model is an important and essential step in model based fault detection and diagnosis (FDD). Factors that are considered in evaluating a model include accuracy, training data requirements, calibration effort, generality, and computational requirements. The objective of this study was to evaluate different modeling approaches for their applicability to model based FDD of vapor compression chillers. Three different models were studied: the Gordon and Ng Universal Chiller model (2nd generation) and a modified version of the ASHRAE Primary Toolkit model, which are both based on first principles, and the DOE-2 chiller model, as implemented in CoolTools{trademark}, which ismore » empirical. The models were compared in terms of their ability to reproduce the observed performance of an older, centrifugal chiller operating in a commercial office building and a newer centrifugal chiller in a laboratory. All three models displayed similar levels of accuracy. Of the first principles models, the Gordon-Ng model has the advantage of being linear in the parameters, which allows more robust parameter estimation methods to be used and facilitates estimation of the uncertainty in the parameter values. The ASHRAE Toolkit Model may have advantages when refrigerant temperature measurements are also available. The DOE-2 model can be expected to have advantages when very limited data are available to calibrate the model, as long as one of the previously identified models in the CoolTools library matches the performance of the chiller in question.« less

Restoring the Pauli principle in the random phase approximation ground state

NASA Astrophysics Data System (ADS)

Kosov, D. S.

2017-12-01

Random phase approximation ground state contains electronic configurations where two (and more) identical electrons can occupy the same molecular spin-orbital violating the Pauli exclusion principle. This overcounting of electronic configurations happens due to quasiboson approximation in the treatment of electron-hole pair operators. We describe the method to restore the Pauli principle in the RPA wavefunction. The proposed theory is illustrated by the calculations of molecular dipole moments and electronic kinetic energies. The Hartree-Fock based RPA, which is corrected for the Pauli principle, gives the results of comparable accuracy with Møller-Plesset second order perturbation theory and coupled-cluster singles and doubles method.

Principles of managing Vancouver type B periprosthetic fractures around cemented polished tapered femoral stems.

PubMed

Quah, Conal; Porteous, Matthew; Stephen, Arthur

2017-05-01

The management of periprosthetic fractures around total hip replacements is a complex and challenging problem. Getting it right first time is an important factor in reducing the morbidity, mortality and financial burden associated with these injuries. Understanding and applying the basic principles of fracture management helps increase the chance of successful treatment. Based on these principles, we suggest a treatment algorithm for managing periprosthetic fractures around polished tapered femoral stems.

High statistics study of in-medium S- and P-wave quarkonium states in lattice Non-relativistic QCD

NASA Astrophysics Data System (ADS)

Kim, S.; Petreczky, P.; Rothkopf, A.

2017-11-01

Many measurements of quarkonium suppression at the LHC, e.g. the nuclear modification factor RAA of J / Ψ, are well described by a multitude of different models. Thus pinpointing the underlying physics aspects is difficult and guidance based on first principles is needed. Here we present the current status of our ongoing high precision study of in-medium spectral properties of both bottomonium and charmonium based on NRQCD on the lattice. This effective field theory allows us to capture the physics of quarkonium without modeling assumptions in a thermal QCD medium. In our study a first principles and realistic description of the QCD medium is provided by state-of-the-art lattices of the HotQCD collaboration at almost physical pion mass. Our updated results corroborate a picture of sequential modification of states with respect to their vacuum binding energy. Using a novel low-gain variant of the Bayesian BR method for reconstructing spectral functions we find that remnant features of the Upsilon may survive up to T ∼ 400MeV, while the χb signal disappears around T ∼ 270MeV. The c c ‾ analysis hints at melting of χc below T ∼ 190MeV while some J / Ψ remnant feature might survive up to T ∼ 245MeV. An improved understanding of the numerical artifacts in the Bayesian approach and the availability of increased statistics have made possible a first quantitative study of the in-medium ground state masses, which tend to lower values as T increases, consistent with lattice potential based studies.

Motion-induced eddy current thermography for high-speed inspection

NASA Astrophysics Data System (ADS)

Wu, Jianbo; Li, Kongjing; Tian, Guiyun; Zhu, Junzhen; Gao, Yunlai; Tang, Chaoqing; Chen, Xiaotian

2017-08-01

This letter proposes a novel motion-induced eddy current based thermography (MIECT) for high-speed inspection. In contrast to conventional eddy current thermography (ECT) based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday's law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

A method for real-time implementation of HOG feature extraction

NASA Astrophysics Data System (ADS)

Luo, Hai-bo; Yu, Xin-rong; Liu, Hong-mei; Ding, Qing-hai

2011-08-01

Histogram of oriented gradient (HOG) is an efficient feature extraction scheme, and HOG descriptors are feature descriptors which is widely used in computer vision and image processing for the purpose of biometrics, target tracking, automatic target detection(ATD) and automatic target recognition(ATR) etc. However, computation of HOG feature extraction is unsuitable for hardware implementation since it includes complicated operations. In this paper, the optimal design method and theory frame for real-time HOG feature extraction based on FPGA were proposed. The main principle is as follows: firstly, the parallel gradient computing unit circuit based on parallel pipeline structure was designed. Secondly, the calculation of arctangent and square root operation was simplified. Finally, a histogram generator based on parallel pipeline structure was designed to calculate the histogram of each sub-region. Experimental results showed that the HOG extraction can be implemented in a pixel period by these computing units.

Nonlinear analysis of 0-3 polarized PLZT microplate based on the new modified couple stress theory

NASA Astrophysics Data System (ADS)

Wang, Liming; Zheng, Shijie

2018-02-01

In this study, based on the new modified couple stress theory, the size- dependent model for nonlinear bending analysis of a pure 0-3 polarized PLZT plate is developed for the first time. The equilibrium equations are derived from a variational formulation based on the potential energy principle and the new modified couple stress theory. The Galerkin method is adopted to derive the nonlinear algebraic equations from governing differential equations. And then the nonlinear algebraic equations are solved by using Newton-Raphson method. After simplification, the new model includes only a material length scale parameter. In addition, numerical examples are carried out to study the effect of material length scale parameter on the nonlinear bending of a simply supported pure 0-3 polarized PLZT plate subjected to light illumination and uniform distributed load. The results indicate the new model is able to capture the size effect and geometric nonlinearity.

Exploiting periodic first-principles calculations in NMR spectroscopy of disordered solids.

PubMed

Ashbrook, Sharon E; Dawson, Daniel M

2013-09-17

Much of the information contained within solid-state nuclear magnetic resonance (NMR) spectra remains unexploited because of the challenges in obtaining high-resolution spectra and the difficulty in assigning those spectra. Recent advances that enable researchers to accurately and efficiently determine NMR parameters in periodic systems have revolutionized the application of density functional theory (DFT) calculations in solid-state NMR spectroscopy. These advances are particularly useful for experimentalists. The use of first-principles calculations aids in both the interpretation and assignment of the complex spectral line shapes observed for solids. Furthermore, calculations provide a method for evaluating potential structural models against experimental data for materials with poorly characterized structures. Determining the structure of well-ordered, periodic crystalline solids can be straightforward using methods that exploit Bragg diffraction. However, the deviations from periodicity, such as compositional, positional, or temporal disorder, often produce the physical properties (such as ferroelectricity or ionic conductivity) that may be of commercial interest. With its sensitivity to the atomic-scale environment, NMR provides a potentially useful tool for studying disordered materials, and the combination of experiment with first-principles calculations offers a particularly attractive approach. In this Account, we discuss some of the issues associated with the practical implementation of first-principles calculations of NMR parameters in solids. We then use two key examples to illustrate the structural insights that researchers can obtain when applying such calculations to disordered inorganic materials. First, we describe an investigation of cation disorder in Y2Ti(2-x)Sn(x)O7 pyrochlore ceramics using (89)Y and (119)Sn NMR. Researchers have proposed that these materials could serve as host phases for the encapsulation of lanthanide- and actinide-bearing radioactive waste. In a second example, we discuss how (17)O NMR can be used to probe the dynamic disorder of H in hydroxyl-humite minerals (nMg2SiO4·Mg(OH)2), and how (19)F NMR can be used to understand F substitution in these systems. The combination of first-principles calculations and multinuclear NMR spectroscopy facilitates the investigation of local structure, disorder, and dynamics in solids. We expect that applications will undoubtedly become more widespread with further advances in computational and experimental methods. Insight into the atomic-scale environment is a crucial first step in understanding the structure-property relationships in solids, and it enables the efficient design of future materials for a range of end uses.

[MLPA technique--principles and use in practice].

PubMed

Rusu, Cristina; Sireteanu, Adriana; Puiu, Maria; Skrypnyk, Cristina; Tomescu, E; Csep, Katalin; Creţ, Victoria; Barbarii, Ligia

2007-01-01

MLPA (Multiplex Ligation-dependent Probe Amplification) is a recently introduced method, based on PCR principle, useful for the detection of different genetic abnormalities (aneuploidies, gene deletions/duplications, subtelomeric rearrangements, methylation status etc). The technique is simple, reliable and cheap. We present this method to discuss its importance for a modern genetic service and to underline its multiple advantages.

Ergonomic design and evaluation of a diagnostic ultrasound transducer holder.

PubMed

Ghasemi, Mohamad Sadegh; Hosseinzadeh, Payam; Zamani, Farhad; Ahmadpoor, Hossein; Dehghan, Naser

2017-12-01

Work-related musculoskeletal disorders (WMSDs) are injuries and disorders that affect the body's movement and musculoskeletal system. Awkward postures represent one of the major ergonomic risk factors that cause WMSDs among sonographers while working with an ultrasound transducer. This study aimed to design and evaluate a new holder for the ultrasound transducer. In the first phase a new holder was designed for the transducer, considering design principles. Evaluation of the new holder was then carried out by electrogoniometry and a locally perceived discomfort (LPD) scale. The application of design principles to the new holder resulted in an improvement of wrist posture and comfort. Wrist angles in extension, flexion, radial deviation and ulnar deviation were lower with utilization of the new holder. The severity of discomfort based on the LPD method in the two modes of work with and without the new holder was reported with values of 1.3 and 1.8, respectively (p < 0.05). Overall, this study indicated that applying ergonomics design principles was effective in minimizing wrist deviation and increasing comfort while working with the new holder.

LQAS: User Beware.

PubMed

Rhoda, Dale A; Fernandez, Soledad A; Fitch, David J; Lemeshow, Stanley

2010-02-01

Researchers around the world are using Lot Quality Assurance Sampling (LQAS) techniques to assess public health parameters and evaluate program outcomes. In this paper, we report that there are actually two methods being called LQAS in the world today, and that one of them is badly flawed. This paper reviews fundamental LQAS design principles, and compares and contrasts the two LQAS methods. We raise four concerns with the simply-written, freely-downloadable training materials associated with the second method. The first method is founded on sound statistical principles and is carefully designed to protect the vulnerable populations that it studies. The language used in the training materials for the second method is simple, but not at all clear, so the second method sounds very much like the first. On close inspection, however, the second method is found to promote study designs that are biased in favor of finding programmatic or intervention success, and therefore biased against the interests of the population being studied. We outline several recommendations, and issue a call for a new high standard of clarity and face validity for those who design, conduct, and report LQAS studies.

An Engineering Method of Civil Jet Requirements Validation Based on Requirements Project Principle

NASA Astrophysics Data System (ADS)

Wang, Yue; Gao, Dan; Mao, Xuming

2018-03-01

A method of requirements validation is developed and defined to meet the needs of civil jet requirements validation in product development. Based on requirements project principle, this method will not affect the conventional design elements, and can effectively connect the requirements with design. It realizes the modern civil jet development concept, which is “requirement is the origin, design is the basis”. So far, the method has been successfully applied in civil jet aircraft development in China. Taking takeoff field length as an example, the validation process and the validation method of the requirements are detailed introduced in the study, with the hope of providing the experiences to other civil jet product design.

Development of a multi-criteria evaluation system to assess growing pig welfare.

PubMed

Martín, P; Traulsen, I; Buxadé, C; Krieter, J

2017-03-01

The aim of this paper was to present an alternative multi-criteria evaluation model to assess animal welfare on farms based on the Welfare Quality® (WQ) project, using an example of welfare assessment of growing pigs. The WQ assessment protocol follows a three-step aggregation process. Measures are aggregated into criteria, criteria into principles and principles into an overall assessment. This study focussed on the first step of the aggregation. Multi-attribute utility theory (MAUT) was used to produce a value of welfare for each criterion. The utility functions and the aggregation function were constructed in two separated steps. The Measuring Attractiveness by a Categorical Based Evaluation Technique (MACBETH) method was used for utility function determination and the Choquet Integral (CI) was used as an aggregation operator. The WQ decision-makers' preferences were fitted in order to construct the utility functions and to determine the CI parameters. The methods were tested with generated data sets for farms of growing pigs. Using the MAUT, similar results were obtained to the ones obtained applying the WQ protocol aggregation methods. It can be concluded that due to the use of an interactive approach such as MACBETH, this alternative methodology is more transparent and more flexible than the methodology proposed by WQ, which allows the possibility to modify the model according, for instance, to new scientific knowledge.

Second-principles method for materials simulations including electron and lattice degrees of freedom

NASA Astrophysics Data System (ADS)

García-Fernández, Pablo; Wojdeł, Jacek C.; Íñiguez, Jorge; Junquera, Javier

2016-05-01

We present a first-principles-based (second-principles) scheme that permits large-scale materials simulations including both atomic and electronic degrees of freedom on the same footing. The method is based on a predictive quantum-mechanical theory—e.g., density functional theory—and its accuracy can be systematically improved at a very modest computational cost. Our approach is based on dividing the electron density of the system into a reference part—typically corresponding to the system's neutral, geometry-dependent ground state—and a deformation part—defined as the difference between the actual and reference densities. We then take advantage of the fact that the bulk part of the system's energy depends on the reference density alone; this part can be efficiently and accurately described by a force field, thus avoiding explicit consideration of the electrons. Then, the effects associated to the difference density can be treated perturbatively with good precision by working in a suitably chosen Wannier function basis. Further, the electronic model can be restricted to the bands of interest. All these features combined yield a very flexible and computationally very efficient scheme. Here we present the basic formulation of this approach, as well as a practical strategy to compute model parameters for realistic materials. We illustrate the accuracy and scope of the proposed method with two case studies, namely, the relative stability of various spin arrangements in NiO (featuring complex magnetic interactions in a strongly-correlated oxide) and the formation of a two-dimensional electron gas at the interface between band insulators LaAlO3 and SrTiO3 (featuring subtle electron-lattice couplings and screening effects). We conclude by discussing ways to overcome the limitations of the present approach (most notably, the assumption of a fixed bonding topology), as well as its many envisioned possibilities and future extensions.

Study on Measuring the Viscosity of Lubricating Oil by Viscometer Based on Hele - Shaw Principle

NASA Astrophysics Data System (ADS)

Li, Longfei

2017-12-01

In order to explore the method of accurately measuring the viscosity value of oil samples using the viscometer based on Hele-Shaw principle, three different measurement methods are designed in the laboratory, and the statistical characteristics of the measured values are compared, in order to get the best measurement method. The results show that the oil sample to be measured is placed in the magnetic field formed by the magnet, and the oil sample can be sucked from the same distance from the magnet. The viscosity value of the sample can be measured accurately.

Numerical simulation of disperse particle flows on a graphics processing unit

NASA Astrophysics Data System (ADS)

Sierakowski, Adam J.

In both nature and technology, we commonly encounter solid particles being carried within fluid flows, from dust storms to sediment erosion and from food processing to energy generation. The motion of uncountably many particles in highly dynamic flow environments characterizes the tremendous complexity of such phenomena. While methods exist for the full-scale numerical simulation of such systems, current computational capabilities require the simplification of the numerical task with significant approximation using closure models widely recognized as insufficient. There is therefore a fundamental need for the investigation of the underlying physical processes governing these disperse particle flows. In the present work, we develop a new tool based on the Physalis method for the first-principles numerical simulation of thousands of particles (a small fraction of an entire disperse particle flow system) in order to assist in the search for new reduced-order closure models. We discuss numerous enhancements to the efficiency and stability of the Physalis method, which introduces the influence of spherical particles to a fixed-grid incompressible Navier-Stokes flow solver using a local analytic solution to the flow equations. Our first-principles investigation demands the modeling of unresolved length and time scales associated with particle collisions. We introduce a collision model alongside Physalis, incorporating lubrication effects and proposing a new nonlinearly damped Hertzian contact model. By reproducing experimental studies from the literature, we document extensive validation of the methods. We discuss the implementation of our methods for massively parallel computation using a graphics processing unit (GPU). We combine Eulerian grid-based algorithms with Lagrangian particle-based algorithms to achieve computational throughput up to 90 times faster than the legacy implementation of Physalis for a single central processing unit. By avoiding all data communication between the GPU and the host system during the simulation, we utilize with great efficacy the GPU hardware with which many high performance computing systems are currently equipped. We conclude by looking forward to the future of Physalis with multi-GPU parallelization in order to perform resolved disperse flow simulations of more than 100,000 particles and further advance the development of reduced-order closure models.

Independent components analysis to increase efficiency of discriminant analysis methods (FDA and LDA): Application to NMR fingerprinting of wine.

PubMed

Monakhova, Yulia B; Godelmann, Rolf; Kuballa, Thomas; Mushtakova, Svetlana P; Rutledge, Douglas N

2015-08-15

Discriminant analysis (DA) methods, such as linear discriminant analysis (LDA) or factorial discriminant analysis (FDA), are well-known chemometric approaches for solving classification problems in chemistry. In most applications, principle components analysis (PCA) is used as the first step to generate orthogonal eigenvectors and the corresponding sample scores are utilized to generate discriminant features for the discrimination. Independent components analysis (ICA) based on the minimization of mutual information can be used as an alternative to PCA as a preprocessing tool for LDA and FDA classification. To illustrate the performance of this ICA/DA methodology, four representative nuclear magnetic resonance (NMR) data sets of wine samples were used. The classification was performed regarding grape variety, year of vintage and geographical origin. The average increase for ICA/DA in comparison with PCA/DA in the percentage of correct classification varied between 6±1% and 8±2%. The maximum increase in classification efficiency of 11±2% was observed for discrimination of the year of vintage (ICA/FDA) and geographical origin (ICA/LDA). The procedure to determine the number of extracted features (PCs, ICs) for the optimum DA models was discussed. The use of independent components (ICs) instead of principle components (PCs) resulted in improved classification performance of DA methods. The ICA/LDA method is preferable to ICA/FDA for recognition tasks based on NMR spectroscopic measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

On the simulation of indistinguishable fermions in the many-body Wigner formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sellier, J.M., E-mail: jeanmichel.sellier@gmail.com; Dimov, I.

2015-01-01

The simulation of quantum systems consisting of interacting, indistinguishable fermions is an incredible mathematical problem which poses formidable numerical challenges. Many sophisticated methods addressing this problem are available which are based on the many-body Schrödinger formalism. Recently a Monte Carlo technique for the resolution of the many-body Wigner equation has been introduced and successfully applied to the simulation of distinguishable, spinless particles. This numerical approach presents several advantages over other methods. Indeed, it is based on an intuitive formalism in which quantum systems are described in terms of a quasi-distribution function, and highly scalable due to its Monte Carlo nature.more » In this work, we extend the many-body Wigner Monte Carlo method to the simulation of indistinguishable fermions. To this end, we first show how fermions are incorporated into the Wigner formalism. Then we demonstrate that the Pauli exclusion principle is intrinsic to the formalism. As a matter of fact, a numerical simulation of two strongly interacting fermions (electrons) is performed which clearly shows the appearance of a Fermi (or exchange–correlation) hole in the phase-space, a clear signature of the presence of the Pauli principle. To conclude, we simulate 4, 8 and 16 non-interacting fermions, isolated in a closed box, and show that, as the number of fermions increases, we gradually recover the Fermi–Dirac statistics, a clear proof of the reliability of our proposed method for the treatment of indistinguishable particles.« less

First-principles Study of Hydrogen depassivation of Mg acceptor by Be in GaN

NASA Astrophysics Data System (ADS)

Zhang, Qiming; Wang, Xiao; Wang, Chihsiang

2010-03-01

The process of hydrogen depassivation of the acceptor by can convert the as-grown high-resistivity -doped into a - conducting material. A first-principles study on the process will be presented. The formation energies of various complex of impurities and point defects have been calculated and compared. The diffusion barriers of the hydrogen atom in the doped GaN have been obtained by the Nudge-Elastic-Band method. The results explain successfully the experimental observation that the hole concentration has been significantly enhanced in a Be-implanted Mg-doped GaN.

Strength of shock-loaded single-crystal tantalum [100] determined using in situ broadband x-ray Laue diffraction.

PubMed

Comley, A J; Maddox, B R; Rudd, R E; Prisbrey, S T; Hawreliak, J A; Orlikowski, D A; Peterson, S C; Satcher, J H; Elsholz, A J; Park, H-S; Remington, B A; Bazin, N; Foster, J M; Graham, P; Park, N; Rosen, P A; Rothman, S R; Higginbotham, A; Suggit, M; Wark, J S

2013-03-15

The strength of shock-loaded single crystal tantalum [100] has been experimentally determined using in situ broadband x-ray Laue diffraction to measure the strain state of the compressed crystal, and elastic constants calculated from first principles. The inferred strength reaches 35 GPa at a shock pressure of 181 GPa and is in excellent agreement with a multiscale strength model [N. R. Barton et al., J. Appl. Phys. 109, 073501 (2011)], which employs a hierarchy of simulation methods over a range of length scales to calculate strength from first principles.

Site-specific electronic structure analysis by channeling EELS and first-principles calculations.

PubMed

Tatsumi, Kazuyoshi; Muto, Shunsuke; Yamamoto, Yu; Ikeno, Hirokazu; Yoshioka, Satoru; Tanaka, Isao

2006-01-01

Site-specific electronic structures were investigated by electron energy loss spectroscopy (EELS) under electron channeling conditions. The Al-K and Mn-L(2,3) electron energy loss near-edge structure (ELNES) of, respectively, NiAl2O4 and Mn3O4 were measured. Deconvolution of the raw spectra with the instrumental resolution function restored the blunt and hidden fine features, which allowed us to interpret the experimental spectral features by comparing with theoretical spectra obtained by first-principles calculations. The present method successfully revealed the electronic structures specific to the differently coordinated cationic sites.

A first principles prediction of the crystal structure of C6Br2ClFH2

NASA Astrophysics Data System (ADS)

Misquitta, Alston J.; Welch, Gareth W. A.; Stone, Anthony J.; Price, Sarah L.

2008-04-01

We have constructed an intermolecular potential for the 1,3-dibromo-2-chloro-5-fluorobenzene molecule from first principles using SAPT(DFT) interaction energy calculations and the Williams-Stone-Misquitta method for obtaining molecular properties in distributed form. This molecule was included in the fourth Blind Test of crystal structure prediction organised by the Cambridge Crystallographic Data Centre. Using our potential, we have predicted the crystal structure of CBrClFH and found the lowest energy solution to be in excellent agreement with the experimentally observed crystal when it was subsequently revealed.

First principles approach to the magneto caloric effect: Application to Ni2MnGa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicholson, Don M; Odbadrakh, Khorgolkhuu; Rusanu, Aurelian

2011-01-01

The magneto-caloric effect (MCE) is a possible route to more efficient heating and cooling of residential and commercial buildings. The search for improved materials is important to the development of a viable MCE based heat pump technology. We have calculated the magnetic structure of a candidate MCE material: Ni2MnGa. The density of magnetic states was calculated with the Wang Landau statistical method utilizing energies fit to those of the locally self-consistent multiple scattering method. The relationships between the density of magnetic states and the field induced adiabatic temperature change and the isothermal entropy change are discussed. (C) 2011 American Institutemore » of Physics.« less

Visualization of atomic-scale phenomena in superconductors: application to FeSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choubey, Peayush; Berlijn, Tom; Kreisel, Andreas

Here we propose a simple method of calculating inhomogeneous, atomic-scale phenomena in superconductors which makes use of the wave function information traditionally discarded in the construction of tight-binding models used in the Bogoliubov-de Gennes equations. The method uses symmetry- based first principles Wannier functions to visualize the effects of superconducting pairing on the distribution of electronic states over atoms within a crystal unit cell. Local symmetries lower than the global lattice symmetry can thus be exhibited as well, rendering theoretical comparisons with scanning tunneling spectroscopy data much more useful. As a simple example, we discuss the geometric dimer states observedmore » near defects in superconducting FeSe.« less

Visualization of atomic-scale phenomena in superconductors: application to FeSe

DOE PAGES

Choubey, Peayush; Berlijn, Tom; Kreisel, Andreas; ...

2014-10-31

Here we propose a simple method of calculating inhomogeneous, atomic-scale phenomena in superconductors which makes use of the wave function information traditionally discarded in the construction of tight-binding models used in the Bogoliubov-de Gennes equations. The method uses symmetry- based first principles Wannier functions to visualize the effects of superconducting pairing on the distribution of electronic states over atoms within a crystal unit cell. Local symmetries lower than the global lattice symmetry can thus be exhibited as well, rendering theoretical comparisons with scanning tunneling spectroscopy data much more useful. As a simple example, we discuss the geometric dimer states observedmore » near defects in superconducting FeSe.« less

A Conceptual Framework and Principles for Trusted Pervasive Health

PubMed Central

Blobel, Bernd Gerhard; Seppälä, Antto Veikko; Sorvari, Hannu Olavi; Nykänen, Pirkko Anneli

2012-01-01

Background Ubiquitous computing technology, sensor networks, wireless communication and the latest developments of the Internet have enabled the rise of a new concept—pervasive health—which takes place in an open, unsecure, and highly dynamic environment (ie, in the information space). To be successful, pervasive health requires implementable principles for privacy and trustworthiness. Objective This research has two interconnected objectives. The first is to define pervasive health as a system and to understand its trust and privacy challenges. The second goal is to build a conceptual model for pervasive health and use it to develop principles and polices which can make pervasive health trustworthy. Methods In this study, a five-step system analysis method is used. Pervasive health is defined using a metaphor of digital bubbles. A conceptual framework model focused on trustworthiness and privacy is then developed for pervasive health. On that model, principles and rules for trusted information management in pervasive health are defined. Results In the first phase of this study, a new definition of pervasive health was created. Using this model, differences between pervasive health and health care are stated. Reviewed publications demonstrate that the widely used principles of predefined and static trust cannot guarantee trustworthiness and privacy in pervasive health. Instead, such an environment requires personal dynamic and context-aware policies, awareness, and transparency. A conceptual framework model focused on information processing in pervasive health is developed. Using features of pervasive health and relations from the framework model, new principles for trusted pervasive health have been developed. The principles propose that personal health data should be under control of the data subject. The person shall have the right to verify the level of trust of any system which collects or processes his or her health information. Principles require that any stakeholder or system collecting or processing health data must support transparency and shall publish its trust and privacy attributes and even its domain specific policies. Conclusions The developed principles enable trustworthiness and guarantee privacy in pervasive health. The implementation of principles requires new infrastructural services such as trust verification and policy conflict resolution. After implementation, the accuracy and usability of principles should be analyzed. PMID:22481297

A novel false color mapping model-based fusion method of visual and infrared images

NASA Astrophysics Data System (ADS)

Qi, Bin; Kun, Gao; Tian, Yue-xin; Zhu, Zhen-yu

2013-12-01

A fast and efficient image fusion method is presented to generate near-natural colors from panchromatic visual and thermal imaging sensors. Firstly, a set of daytime color reference images are analyzed and the false color mapping principle is proposed according to human's visual and emotional habits. That is, object colors should remain invariant after color mapping operations, differences between infrared and visual images should be enhanced and the background color should be consistent with the main scene content. Then a novel nonlinear color mapping model is given by introducing the geometric average value of the input visual and infrared image gray and the weighted average algorithm. To determine the control parameters in the mapping model, the boundary conditions are listed according to the mapping principle above. Fusion experiments show that the new fusion method can achieve the near-natural appearance of the fused image, and has the features of enhancing color contrasts and highlighting the infrared brilliant objects when comparing with the traditional TNO algorithm. Moreover, it owns the low complexity and is easy to realize real-time processing. So it is quite suitable for the nighttime imaging apparatus.

A review on ab initio studies of static, transport, and optical properties of polystyrene under extreme conditions for inertial confinement fusion applications

NASA Astrophysics Data System (ADS)

Hu, S. X.; Collins, L. A.; Boehly, T. R.; Ding, Y. H.; Radha, P. B.; Goncharov, V. N.; Karasiev, V. V.; Collins, G. W.; Regan, S. P.; Campbell, E. M.

2018-05-01

Polystyrene (CH), commonly known as "plastic," has been one of the widely used ablator materials for capsule designs in inertial confinement fusion (ICF). Knowing its precise properties under high-energy-density conditions is crucial to understanding and designing ICF implosions through radiation-hydrodynamic simulations. For this purpose, systematic ab initio studies on the static, transport, and optical properties of CH, in a wide range of density and temperature conditions (ρ = 0.1 to 100 g/cm3 and T = 103 to 4 × 106 K), have been conducted using quantum molecular dynamics (QMD) simulations based on the density functional theory. We have built several wide-ranging, self-consistent material-properties tables for CH, such as the first-principles equation of state, the QMD-based thermal conductivity (κQMD) and ionization, and the first-principles opacity table. This paper is devoted to providing a review on (1) what results were obtained from these systematic ab initio studies; (2) how these self-consistent results were compared with both traditional plasma-physics models and available experiments; and (3) how these first-principles-based properties of polystyrene affect the predictions of ICF target performance, through both 1-D and 2-D radiation-hydrodynamic simulations. In the warm dense regime, our ab initio results, which can significantly differ from predictions of traditional plasma-physics models, compared favorably with experiments. When incorporated into hydrocodes for ICF simulations, these first-principles material properties of CH have produced significant differences over traditional models in predicting 1-D/2-D target performance of ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility. Finally, we will discuss the implications of these studies on the current small-margin ICF target designs using a CH ablator.

Theoretical Principles to Guide the Teaching of Adjectives to Children Who Struggle With Word Learning: Synthesis of Experimental and Naturalistic Research With Principles of Learning Theory.

PubMed

Ricks, Samantha L; Alt, Mary

2016-07-01

The purpose of this tutorial is to provide clinicians with a theoretically motivated and evidence-based approach to teaching adjectives to children who struggle with word learning. Given that there are almost no treatment studies to guide this topic, we have synthesized findings from experimental and theoretical literature to come up with a principles-based approach to treatment. We provide a sample lesson plan, incorporating our 3 theoretical principles, and describe the materials chosen and methods used during treatment and assessment. This approach is theoretically motivated, but it needs to be empirically tested.

[Research on fast classification based on LIBS technology and principle component analyses].

PubMed

Yu, Qi; Ma, Xiao-Hong; Wang, Rui; Zhao, Hua-Feng

2014-11-01

Laser-induced breakdown spectroscopy (LIBS) and the principle component analysis (PCA) were combined to study aluminum alloy classification in the present article. Classification experiments were done on thirteen different kinds of standard samples of aluminum alloy which belong to 4 different types, and the results suggested that the LIBS-PCA method can be used to aluminum alloy fast classification. PCA was used to analyze the spectrum data from LIBS experiments, three principle components were figured out that contribute the most, the principle component scores of the spectrums were calculated, and the scores of the spectrums data in three-dimensional coordinates were plotted. It was found that the spectrum sample points show clear convergence phenomenon according to the type of aluminum alloy they belong to. This result ensured the three principle components and the preliminary aluminum alloy type zoning. In order to verify its accuracy, 20 different aluminum alloy samples were used to do the same experiments to verify the aluminum alloy type zoning. The experimental result showed that the spectrum sample points all located in their corresponding area of the aluminum alloy type, and this proved the correctness of the earlier aluminum alloy standard sample type zoning method. Based on this, the identification of unknown type of aluminum alloy can be done. All the experimental results showed that the accuracy of principle component analyses method based on laser-induced breakdown spectroscopy is more than 97.14%, and it can classify the different type effectively. Compared to commonly used chemical methods, laser-induced breakdown spectroscopy can do the detection of the sample in situ and fast with little sample preparation, therefore, using the method of the combination of LIBS and PCA in the areas such as quality testing and on-line industrial controlling can save a lot of time and cost, and improve the efficiency of detection greatly.

Prototypes of newly conceived inorganic and biological sensors for health and environmental applications.

PubMed

Nicolini, Claudio; Adami, Manuela; Sartore, Marco; Bragazzi, Nicola Luigi; Bavastrello, Valter; Spera, Rosanna; Pechkova, Eugenia

2012-12-12

This paper describes the optimal implementation of three newly conceived sensors for both health and environmental applications, utilizing a wide range of detection methods and complex nanocomposites. The first one is inorganic and based on matrices of calcium oxide, the second is based on protein arrays and a third one is based on Langmuir-Blodgett laccase multi-layers. Special attention was paid to detecting substances significant to the environment (such as carbon dioxide) and medicine (drug administration, cancer diagnosis and prognosis) by means of amperometric, quartz crystal microbalance with frequency (QCM_F) and quartz crystal microbalance with dissipation monitoring (QCM_D) technologies. The resulting three implemented nanosensors are described here along with proofs of principle and their corresponding applications.

Underwater electric field detection system based on weakly electric fish

NASA Astrophysics Data System (ADS)

Xue, Wei; Wang, Tianyu; Wang, Qi

2018-04-01

Weakly electric fish sense their surroundings in complete darkness by their active electric field detection system. However, due to the insufficient detection capacity of the electric field, the detection distance is not enough, and the detection accuracy is not high. In this paper, a method of underwater detection based on rotating current field theory is proposed to improve the performance of underwater electric field detection system. First of all, we built underwater detection system based on the theory of the spin current field mathematical model with the help of the results of previous researchers. Then we completed the principle prototype and finished the metal objects in the water environment detection experiments, laid the foundation for the further experiments.

Accurately predicting the structure, density, and hydrostatic compression of crystalline β-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane based on its wave-function-based potential

NASA Astrophysics Data System (ADS)

Song, H.-J.; Huang, F.

2011-09-01

A wave-function-based intermolecular potential of the β phase 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) molecule has been constructed from first principles using the Williams-Stone-Misquitta method and the symmetry-adapted perturbation theory. Using the potential and its derivatives, we have accurately predicted not only the structure and lattice energy of the crystalline β-HMX at 0 K, but also its densities at temperatures of 0-403 K within an accuracy of 1% of density. The calculated densities at pressures within 0-6 GPa excellently agree with the results from the experiments on hydrostatic compression.

Early Introduction of an Evidence-based Medicine Course to Preclinical Medical Students

PubMed Central

Srinivasan, Malathi; Weiner, Michael; Breitfeld, Philip P; Brahmi, Fran; Dickerson, Keith L; Weiner, Gary

2002-01-01

Evidence-based Medicine (EBM) has been increasingly integrated into medical education curricula. Using an observational research design, we evaluated the feasibility of introducing a 1-month problem-based EBM course for 139 first-year medical students at a large university center. We assessed program performance through the use of a web-based curricular component and practice exam, final examination scores, student satisfaction surveys, and a faculty questionnaire. Students demonstrated active involvement in learning EBM and ability to use EBM principles. Facilitators felt that students performed well and compared favorably with residents whom they had supervised in the past year. Both faculty and students were satisfied with the EBM course. To our knowledge, this is the first report to demonstrate that early introduction of EBM principles as a short course to preclinical medical students is feasible and practical. PMID:11903776

Research on damping properties optimization of variable-stiffness plate

NASA Astrophysics Data System (ADS)

Wen-kai, QI; Xian-tao, YIN; Cheng, SHEN

2016-09-01

This paper investigates damping optimization design of variable-stiffness composite laminated plate, which means fibre paths can be continuously curved and fibre angles are distinct for different regions. First, damping prediction model is developed based on modal dissipative energy principle and verified by comparing with modal testing results. Then, instead of fibre angles, the element stiffness and damping matrixes are translated to be design variables on the basis of novel Discrete Material Optimization (DMO) formulation, thus reducing the computation time greatly. Finally, the modal damping capacity of arbitrary order is optimized using MMA (Method of Moving Asymptotes) method. Meanwhile, mode tracking technique is employed to investigate the variation of modal shape. The convergent performance of interpolation function, first order specific damping capacity (SDC) optimization results and variation of modal shape in different penalty factor are discussed. The results show that the damping properties of the variable-stiffness plate can be increased by 50%-70% after optimization.

Solar Corona Simulation Model With Positivity-preserving Property

NASA Astrophysics Data System (ADS)

Feng, X. S.

2015-12-01

Positivity-preserving is one of crucial problems in solar corona simulation. In such numerical simulation of low plasma β region, keeping density and pressure is a first of all matter to obtain physical sound solution. In the present paper, we utilize the maximum-principle-preserving flux limiting technique to develop a class of second order positivity-preserving Godunov finite volume HLL methods for the solar wind plasma MHD equations. Based on the underlying first order building block of positivity preserving Lax-Friedrichs, our schemes, under the constrained transport (CT) and generalized Lagrange multiplier (GLM) framework, can achieve high order accuracy, a discrete divergence-free condition and positivity of the numerical solution simultaneously without extra CFL constraints. Numerical results in four Carrington rotation during the declining, rising, minimum and maximum solar activity phases are provided to demonstrate the performance of modeling small plasma beta with positivity-preserving property of the proposed method.

A different method for calculation of the deflection angle of light passing close to a massive object by Fermat’s principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akkus, Harun, E-mail: physicisthakkus@gmail.com

2013-12-15

We introduce a method for calculating the amount of deflection angle of light passing close to a massive object. It is based on Fermat’s principle. The varying refractive index of medium around the massive object is obtained from the Buckingham pi-theorem. Highlights: •A different and simpler method for the calculation of deflection angle of light. •Not a curved space, only 2-D Euclidean space. •Getting a varying refractive index from the Buckingham pi-theorem. •Obtaining the some results of general relativity from Fermat’s principle.

First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results

NASA Astrophysics Data System (ADS)

Yamaguchi, Kizashi; Nishihara, Satomichi; Saito, Toru; Yamanaka, Shusuke; Kitagawa, Yasutaka; Kawakami, Takashi; Yamada, Satoru; Isobe, Hiroshi; Okumura, Mitsutaka

2015-01-01

First principle calculations of effective exchange integrals (J) in the Heisenberg model for diradical species were performed by both symmetry-adapted (SA) multi-reference (MR) and broken-symmetry (BS) single reference (SR) methods. Mukherjee-type (Mk) state specific (SS) MR coupled-cluster (CC) calculations by the use of natural orbital (NO) references of ROHF, UHF, UDFT and CASSCF solutions were carried out to elucidate J values for di- and poly-radical species. Spin-unrestricted Hartree Fock (UHF) based coupled-cluster (CC) computations were also performed to these species. Comparison between UHF-NO(UNO)-MkMRCC and BS UHF-CC computational results indicated that spin-contamination of UHF-CC solutions still remains at the SD level. In order to eliminate the spin contamination, approximate spin-projection (AP) scheme was applied for UCC, and the AP procedure indeed corrected the error to yield good agreement with MkMRCC in energy. The CC double with spin-unrestricted Brueckner's orbital (UBD) was furthermore employed for these species, showing that spin-contamination involved in UHF solutions is largely suppressed, and therefore AP scheme for UBCCD removed easily the rest of spin-contamination. We also performed spin-unrestricted pure- and hybrid-density functional theory (UDFT) calculations of diradical and polyradical species. Three different computational schemes for total spin angular momentums were examined for the AP correction of the hybrid (H) UDFT. HUDFT calculations followed by AP, HUDFT(AP), yielded the S-T gaps that were qualitatively in good agreement with those of MkMRCCSD, UHF-CC(AP) and UB-CC(AP). Thus a systematic comparison among MkMRCCSD, UCC(AP) UBD(AP) and UDFT(AP) was performed concerning with the first principle calculations of J values in di- and poly-radical species. It was found that BS (AP) methods reproduce MkMRCCSD results, indicating their applicability to large exchange coupled systems.

Using "First Principles of Instruction" to Design Secondary School Mathematics Flipped Classroom: The Findings of Two Exploratory Studies

ERIC Educational Resources Information Center

Lo, Chung Kwan; Hew, Khe Foon

2017-01-01

Flipping the classroom is a current pedagogical innovation in many schools and universities. Although interest in flipped classroom (or Inverted Classroom) continues to grow, its implementation so far has been driven more by teachers' intuitive beliefs, rather than empirically-based principles. Many studies merely replace in-class instructions…

The Impact of Learning Styles on Achievement in Principles of Microeconomics: A Natural Experiment

ERIC Educational Resources Information Center

Terregrossa, Ralph; Englander, Fred; Englander, Valerie

2009-01-01

This study investigates how a natural experiment occurring in the teaching of principles of microeconomics allows a test of the Dunn and Dunn learning styles model (Dunn & Griggs, 2000). The material for the first exam, based on essential definitions and theoretical foundations, was taught in a conventional, inductive style, more compatible with…

A Professional Dilemma: Following the Principle or the Principal?

ERIC Educational Resources Information Center

Zirkel, Perry A.

2012-01-01

This article reports on a case that resulted in a published court decision which illustrates a dilemma at the intersection of the No Child Left Behind Act (NCLB) and the Individuals with Disabilities Education Act (IDEA). On first impression, the finding that teachers were operating based on professional principle seems to validate their actions.…

BPM analysis of all-optical fiber interferometric sensor based on a U-shape microcavity

NASA Astrophysics Data System (ADS)

Wu, Hongbin; Yuan, Lei; Wang, Sumei; Zhao, Longjiang; Cao, Zhitao

2014-02-01

Reflectivity spectrum of beam propagation method (BPM), for the first time to the best of our knowledge, is realized and utilized to model all-optical fiber interferometric sensor formed by a U-shape microcavity embedded in a single mode optical fiber and illustrate the principle of sensor structures varied by the length and the depth of U-shape microcavity. BPM analysis gives a constructive guideline to get a high interferometric fringe visibility which is most important for sensing application. The simulated results are completely in agreement with the interferometric sensor principle of Fabry-Perot interferometer (FPI) theory. With the conclusion of FPI sensor, refractive index (RI) sensitivity and temperature sensitivity are then simulated and obtained as 1049+/-5.2nm/RIU (refractive index unit) within RI range of solutions and 1.04+/-0.03pm/°C respectively.

A unified perspective on preferential solvation and adsorption based on inhomogeneous solvation theory

NASA Astrophysics Data System (ADS)

Shimizu, Seishi; Matubayasi, Nobuyuki

2018-02-01

How cosolvents affects solvation has been revealed through the independent determination of solute-solvent and solute-cosolvent interactions guaranteed by the phase rule. Based on the first principles of inhomogeneous solvation theory, we present here a general matrix theory encompassing both preferential solvation and surface adsorption. The central role of the stability conditions, that govern how many excess numbers (surface excesses) are independently determinable, have been clarified from the first principles. The advantage of the inhomogeneous approach has been demonstrated to be in its ease in treating solvation and adsorption in a unified manner, while its disadvantage, for example in membrane dialysis experiments, can be overcome by the inhomogeneous-homogeneous conversion.

Equilibration and analysis of first-principles molecular dynamics simulations of water

NASA Astrophysics Data System (ADS)

Dawson, William; Gygi, François

2018-03-01

First-principles molecular dynamics (FPMD) simulations based on density functional theory are becoming increasingly popular for the description of liquids. In view of the high computational cost of these simulations, the choice of an appropriate equilibration protocol is critical. We assess two methods of estimation of equilibration times using a large dataset of first-principles molecular dynamics simulations of water. The Gelman-Rubin potential scale reduction factor [A. Gelman and D. B. Rubin, Stat. Sci. 7, 457 (1992)] and the marginal standard error rule heuristic proposed by White [Simulation 69, 323 (1997)] are evaluated on a set of 32 independent 64-molecule simulations of 58 ps each, amounting to a combined cumulative time of 1.85 ns. The availability of multiple independent simulations also allows for an estimation of the variance of averaged quantities, both within MD runs and between runs. We analyze atomic trajectories, focusing on correlations of the Kohn-Sham energy, pair correlation functions, number of hydrogen bonds, and diffusion coefficient. The observed variability across samples provides a measure of the uncertainty associated with these quantities, thus facilitating meaningful comparisons of different approximations used in the simulations. We find that the computed diffusion coefficient and average number of hydrogen bonds are affected by a significant uncertainty in spite of the large size of the dataset used. A comparison with classical simulations using the TIP4P/2005 model confirms that the variability of the diffusivity is also observed after long equilibration times. Complete atomic trajectories and simulation output files are available online for further analysis.

Equilibration and analysis of first-principles molecular dynamics simulations of water.

PubMed

Dawson, William; Gygi, François

2018-03-28

First-principles molecular dynamics (FPMD) simulations based on density functional theory are becoming increasingly popular for the description of liquids. In view of the high computational cost of these simulations, the choice of an appropriate equilibration protocol is critical. We assess two methods of estimation of equilibration times using a large dataset of first-principles molecular dynamics simulations of water. The Gelman-Rubin potential scale reduction factor [A. Gelman and D. B. Rubin, Stat. Sci. 7, 457 (1992)] and the marginal standard error rule heuristic proposed by White [Simulation 69, 323 (1997)] are evaluated on a set of 32 independent 64-molecule simulations of 58 ps each, amounting to a combined cumulative time of 1.85 ns. The availability of multiple independent simulations also allows for an estimation of the variance of averaged quantities, both within MD runs and between runs. We analyze atomic trajectories, focusing on correlations of the Kohn-Sham energy, pair correlation functions, number of hydrogen bonds, and diffusion coefficient. The observed variability across samples provides a measure of the uncertainty associated with these quantities, thus facilitating meaningful comparisons of different approximations used in the simulations. We find that the computed diffusion coefficient and average number of hydrogen bonds are affected by a significant uncertainty in spite of the large size of the dataset used. A comparison with classical simulations using the TIP4P/2005 model confirms that the variability of the diffusivity is also observed after long equilibration times. Complete atomic trajectories and simulation output files are available online for further analysis.

Reciprocity-Based Reasons for Benefiting Research Participants: Most Fail, the Most Plausible is Problematic

PubMed Central

Sofaer, Neema

2014-01-01

A common reason for giving research participants post-trial access (PTA) to the trial intervention appeals to reciprocity, the principle, stated most generally, that if one person benefits a second, the second should reciprocate: benefit the first in return. Many authors consider it obvious that reciprocity supports PTA. Yet their reciprocity principles differ, with many authors apparently unaware of alternative versions. This article is the first to gather the range of reciprocity principles. It finds that: (1) most are false. (2) The most plausible principle, which is also problematic, applies only when participants experience significant net risks or burdens. (3) Seldom does reciprocity support PTA for participants or give researchers stronger reason to benefit participants than equally needy non-participants. (4) Reciprocity fails to explain the common view that it is bad when participants in a successful trial have benefited from the trial intervention but lack PTA to it. PMID:24602060

First-principles atomistic Wulff constructions for an equilibrium rutile TiO2 shape modeling

NASA Astrophysics Data System (ADS)

Jiang, Fengzhou; Yang, Lei; Zhou, Dali; He, Gang; Zhou, Jiabei; Wang, Fanhou; Chen, Zhi-Gang

2018-04-01

Identifying the exposed surfaces of rutile TiO2 crystal is crucial for its industry application and surface engineering. In this study, the shape of the rutile TiO2 was constructed by applying equilibrium thermodynamics of TiO2 crystals via first-principles density functional theory (DFT) and Wulff principles. From the DFT calculations, the surface energies of six low-index stoichiometric facets of TiO2 are determined after the calibrations of crystal structure. And then, combined surface energy calculations and Wulff principles, a geometric model of equilibrium rutile TiO2 is built up, which is coherent with the typical morphology of fully-developed equilibrium TiO2 crystal. This study provides fundamental theoretical guidance for the surface analysis and surface modification of the rutile TiO2-based materials from experimental research to industry manufacturing.

New Simulation Methods to Facilitate Achieving a Mechanistic Understanding of Basic Pharmacology Principles in the Classroom

ERIC Educational Resources Information Center

Grover, Anita; Lam, Tai Ning; Hunt, C. Anthony

2008-01-01

We present a simulation tool to aid the study of basic pharmacology principles. By taking advantage of the properties of agent-based modeling, the tool facilitates taking a mechanistic approach to learning basic concepts, in contrast to the traditional empirical methods. Pharmacodynamics is a particular aspect of pharmacology that can benefit from…

Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations

PubMed Central

Law, Jodi Woan-Fei; Ab Mutalib, Nurul-Syakima; Chan, Kok-Gan; Lee, Learn-Han

2015-01-01

The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases. PMID:25628612

Non-uniform refractive index field measurement based on light field imaging technique

NASA Astrophysics Data System (ADS)

Du, Xiaokun; Zhang, Yumin; Zhou, Mengjie; Xu, Dong

2018-02-01

In this paper, a method for measuring the non-uniform refractive index field based on the light field imaging technique is proposed. First, the light field camera is used to collect the four-dimensional light field data, and then the light field data is decoded according to the light field imaging principle to obtain image sequences with different acquisition angles of the refractive index field. Subsequently PIV (Particle Image Velocimetry) technique is used to extract ray offset of each image. Finally, the distribution of non-uniform refractive index field can be calculated by inversing the deflection of light rays. Compared with traditional optical methods which require multiple optical detectors from multiple angles to synchronously collect data, the method proposed in this paper only needs a light field camera and shoot once. The effectiveness of the method has been verified by the experiment which quantitatively measures the distribution of the refractive index field above the flame of the alcohol lamp.

A New Approach for Mining Order-Preserving Submatrices Based on All Common Subsequences.

PubMed

Xue, Yun; Liao, Zhengling; Li, Meihang; Luo, Jie; Kuang, Qiuhua; Hu, Xiaohui; Li, Tiechen

2015-01-01

Order-preserving submatrices (OPSMs) have been applied in many fields, such as DNA microarray data analysis, automatic recommendation systems, and target marketing systems, as an important unsupervised learning model. Unfortunately, most existing methods are heuristic algorithms which are unable to reveal OPSMs entirely in NP-complete problem. In particular, deep OPSMs, corresponding to long patterns with few supporting sequences, incur explosive computational costs and are completely pruned by most popular methods. In this paper, we propose an exact method to discover all OPSMs based on frequent sequential pattern mining. First, an existing algorithm was adjusted to disclose all common subsequence (ACS) between every two row sequences, and therefore all deep OPSMs will not be missed. Then, an improved data structure for prefix tree was used to store and traverse ACS, and Apriori principle was employed to efficiently mine the frequent sequential pattern. Finally, experiments were implemented on gene and synthetic datasets. Results demonstrated the effectiveness and efficiency of this method.

Status in calculating electronic excited states in transition metal oxides from first principles.

PubMed

Bendavid, Leah Isseroff; Carter, Emily Ann

2014-01-01

Characterization of excitations in transition metal oxides is a crucial step in the development of these materials for photonic and optoelectronic applications. However, many transition metal oxides are considered to be strongly correlated materials, and their complex electronic structure is challenging to model with many established quantum mechanical techniques. We review state-of-the-art first-principles methods to calculate charged and neutral excited states in extended materials, and discuss their application to transition metal oxides. We briefly discuss developments in density functional theory (DFT) to calculate fundamental band gaps, and introduce time-dependent DFT, which can model neutral excitations. Charged excitations can be described within the framework of many-body perturbation theory based on Green's functions techniques, which predominantly employs the GW approximation to the self-energy to facilitate a feasible solution to the quasiparticle equations. We review the various implementations of the GW approximation and evaluate each approach in its calculation of fundamental band gaps of many transition metal oxides. We also briefly review the related Bethe-Salpeter equation (BSE), which introduces an electron-hole interaction between GW-derived quasiparticles to describe accurately neutral excitations. Embedded correlated wavefunction theory is another framework used to model localized neutral or charged excitations in extended materials. Here, the electronic structure of a small cluster is modeled within correlated wavefunction theory, while its coupling to its environment is represented by an embedding potential. We review a number of techniques to represent this background potential, including electrostatic representations and electron density-based methods, and evaluate their application to transition metal oxides.

Other ways of measuring `Big G'

NASA Astrophysics Data System (ADS)

Rothleitner, Christian

2016-03-01

In 1798, the British scientist Henry Cavendish performed the first laboratory experiment to determine the gravitational force between two massive bodies. From his result, Newton's gravitational constant, G, was calculated. Cavendish's measurement principle was the torsion balance invented by John Michell some 15 years before. During the following two centuries, more than 300 new measurements followed. Although technology - and physics - developed rapidly during this time, surprisingly, most experiments were still based on the same principle. In fact, the most accurate determination of G to date is a measurement based on the torsion balance principle. Despite the fact that G was one of the first fundamental physical constants ever measured, and despite the huge number of experiments performed on it to this day, its CODATA recommended value still has the highest standard measurement uncertainty when compared to other fundamental physical constants. Even more serious is the fact that even measurements based on the same principle often do not overlap within their attributed standard uncertainties. It must be assumed that various experiments are subject to one or more unknown biases. In this talk I will present some alternative experimental setups to the torsion balance which have been performed or proposed to measure G. Although their estimated uncertainties are often higher than most torsion balance experiments, revisiting such ideas is worthwhile. Advances in technology could offer solutions to problems which were previously insurmountable, these solutions could result in lower measurement uncertainties. New measurement principles could also help to uncover hidden systematic effects.

Motion control of a gantry crane with a container

NASA Astrophysics Data System (ADS)

Shugailo, T. S.; Yushkov, M. P.

2018-05-01

The transportation of a container by a gantry crane in a given time from one point of space to another is considered. The system is at rest at the end of the motion. A maximum admissible speed is taken into account. The control force is found using either the Pontryagin maximum principle or the generalized Gauss principle. The advantages of the second method over the first one is demonstrated.

Changing the Paradigm: Simulation, a Method of First Resort

DTIC Science & Technology

2011-09-01

Environment xvii USAF United States Air Force USD(I) Under Secretary of Defense (Intelligence) V&V Verification and Validation VIC Vector -in...continued use throughout the operations research community, and is perhaps best known from Harvey Wagner’s seminal textbook Principles of Operations...pages 887 and 890 of Harvey Wagner’s seminal textbook Principles of Operations Research (Wagner, 1969). Why was this the paradigm of the time? Was

Higher-dimensional Wannier Interpolation for the Modern Theory of the Dzyaloshinskii-Moriya Interaction: Application to Co-based Trilayers

NASA Astrophysics Data System (ADS)

Hanke, Jan-Philipp; Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy

2018-04-01

We present an advanced first-principles formalism to evaluate the Dzyaloshinskii-Moriya interaction (DMI) in its modern theory as well as Berry curvatures in complex spaces based on a higher-dimensional Wannier interpolation. Our method is applied to the Co-based trilayer systems IrδPt1-δ/Co/Pt and AuγPt1-γ/Co/Pt, where we gain insights into the correlations between the electronic structure and the DMI, and we uncover prominent sign changes of the chiral interaction with the overlayer composition. Beyond the discussed phenomena, the scope of applications of our Wannier-based scheme is particularly broad as it is ideally suited to study efficiently the Hamiltonian evolution under the slow variation of very general parameters.

The reliability of Cavalier's principle of stereological method in determining volumes of enchondromas using the computerized tomography tools.

PubMed

Acar, Nihat; Karakasli, Ahmet; Karaarslan, Ahmet; Mas, Nermin Ng; Hapa, Onur

2017-01-01

Volumetric measurements of benign tumors enable surgeons to trace volume changes during follow-up periods. For a volumetric measurement technique to be applicable, it should be easy, rapid, and inexpensive and should carry a high interobserver reliability. We aimed to assess the interobserver reliability of a volumetric measurement technique using the Cavalier's principle of stereological methods. The computerized tomography (CT) of 15 patients with a histopathologically confirmed diagnosis of enchondroma with variant tumor sizes and localizations was retrospectively reviewed for interobserver reliability evaluation of the volumetric stereological measurement with the Cavalier's principle, V = t × [((SU) × d) /SL]2 × Σ P. The volumes of the 15 tumors collected by the observers are demonstrated in Table 1. There was no statistical significance between the first and second observers ( p = 0.000 and intraclass correlation coefficient = 0.970) and between the first and third observers ( p = 0.000 and intraclass correlation coefficient = 0.981). No statistical significance was detected between the second and third observers ( p = 0.000 and intraclass correlation coefficient = 0.976). The Cavalier's principle with the stereological technique using the CT scans is an easy, rapid, and inexpensive technique in volumetric evaluation of enchondromas with a trustable interobserver reliability.

[Experience summary of professor WANG Fuchun's "Zhenjing Anshen" acupuncture method for insomnia].

PubMed

Li, Tie; Ha, Lijuan; Cao, Fang; Zhi, Mujun; Wang, Fuchun

2015-11-01

The experience of "Zhenjing Anshen" acupuncture method originally created by professor WANG Fuchun for treatment of insomnia was introduced in this paper. From aspects of insomnia pathogenesis, theoretical foundation, characteristics of acupoint selection, needing methods, needing time, etc., the experience of Professor WANG Fuchun for treatment of insomnia was explained. The "Zhenjing Anshen" acupuncture method proposed, for the first time, "new three layers" method of acupoint selection, including Sishencong (EX-HN 1), Shenmen (HT 7), Sanyinjiao (SP 6). This method presents the principles of acupoint selection along meridian, acupoint selection based on essence-qi-spirit, harmony of yin and yang. The acupuncture manipulation is emphasized, and treating time (the period of the day from 3 pm to 5 pm) is focused on; acupoint selection is simple but essential, and acupoint combination is scientific, which receives notable therapeutic effect in clinic.

A novel phase retrieval method from three-wavelength in-line phase-shifting interferograms based on positive negative 2π phase shifts

NASA Astrophysics Data System (ADS)

Xu, Xiaoqing; Wang, Yawei; Ji, Ying; Xu, Yuanyuan; Xie, Ming

2018-01-01

A new method to extract quantitative phases for each wavelength from three-wavelength in-line phase-shifting interferograms is proposed. Firstly, seven interferograms with positive negative 2π phase shifts are sequentially captured by using the phase-shifting technique. Secondly, six dc-term suppressed intensities can be achieved by the use of the algebraic algorithm. Finally, the wrapped phases at the three wavelengths can be acquired simultaneously from these six interferograms add-subtracting by employing the trigonometric function method. The surface morphology with increased ambiguity-free range at synthetic beat wavelength can be obtained, while maintaining the low noise precision of the single wavelength measurement, by combining this method with three-wavelength phase unwrapping method. We illustrate the principle of this algorithm, and the simulated experiments of the spherical cap and the HeLa cell are conducted to prove our proposed method, respectively.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply.

PubMed

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-03-31

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply

PubMed Central

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-01-01

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems. PMID:29614749

Appearance-based representative samples refining method for palmprint recognition

NASA Astrophysics Data System (ADS)

Wen, Jiajun; Chen, Yan

2012-07-01

The sparse representation can deal with the lack of sample problem due to utilizing of all the training samples. However, the discrimination ability will degrade when more training samples are used for representation. We propose a novel appearance-based palmprint recognition method. We aim to find a compromise between the discrimination ability and the lack of sample problem so as to obtain a proper representation scheme. Under the assumption that the test sample can be well represented by a linear combination of a certain number of training samples, we first select the representative training samples according to the contributions of the samples. Then we further refine the training samples by an iteration procedure, excluding the training sample with the least contribution to the test sample for each time. Experiments on PolyU multispectral palmprint database and two-dimensional and three-dimensional palmprint database show that the proposed method outperforms the conventional appearance-based palmprint recognition methods. Moreover, we also explore and find out the principle of the usage for the key parameters in the proposed algorithm, which facilitates to obtain high-recognition accuracy.

Robustness analysis of a green chemistry-based model for the ...

EPA Pesticide Factsheets

This paper proposes a robustness analysis based on Multiple Criteria Decision Aiding (MCDA). The ensuing model was used to assess the implementation of green chemistry principles in the synthesis of silver nanoparticles. Its recommendations were also compared to an earlier developed model for the same purpose to investigate concordance between the models and potential decision support synergies. A three-phase procedure was adopted to achieve the research objectives. Firstly, an ordinal ranking of the evaluation criteria used to characterize the implementation of green chemistry principles was identified through relative ranking analysis. Secondly, a structured selection process for an MCDA classification method was conducted, which ensued in the identification of Stochastic Multi-Criteria Acceptability Analysis (SMAA). Lastly, the agreement of the classifications by the two MCDA models and the resulting synergistic role of decision recommendations were studied. This comparison showed that the results of the two models agree between 76% and 93% of the simulation set-ups and it confirmed that different MCDA models provide a more inclusive and transparent set of recommendations. This integrative research confirmed the beneficial complementary use of MCDA methods to aid responsible development of nanosynthesis, by accounting for multiple objectives and helping communication of complex information in a comprehensive and traceable format, suitable for stakeholders and

Broadband FBG resonator seismometer: principle, key technique, self-noise, and seismic response analysis.

PubMed

Huang, Wenzhu; Zhang, Wentao; Luo, Yingbo; Li, Li; Liu, Wenyi; Li, Fang

2018-04-16

A broadband optical fiber seismometer based on FBG resonator is proposed for earthquake monitoring. The principle and key technique, high-resolution ultralow-frequency wavelength interrogation by dual-laser swept frequency and beat frequency method, are discussed and analyzed. From the simulation and test results, the seismometer works at broadband range from 0.01 Hz to 10 Hz with a sensitivity of better than 330 pm/g and the wavelength resolution of the interrogation system is better than 0.001 pm/√Hz from 0.1 Hz to 10 Hz. A three-channel correlation method is used to measure the self-noise of the seismometer. It reaches a noise level of 2.7 × 10 -7 ms -2 /√Hz@0.1 Hz, which is lower than the earth's background noise (the new high noise model, NHNM). An earthquake monitoring experiment is conducted in a low noise seismic station. The recorded seismic waves are analyzed, which suggests that the proposed seismometer has the ability to record the close microearthquake and distant great earthquake with a high signal-noise ratio (SNR). This is the first time that a FBG-based middle-long period seismometer with lower self-noise than NHNM and large dynamic range (100 dB) is reported.

First-principles definition and measurement of planetary electromagnetic-energy budget.

PubMed

Mishchenko, Michael I; Lock, James A; Lacis, Andrew A; Travis, Larry D; Cairns, Brian

2016-06-01

The imperative to quantify the Earth's electromagnetic-energy budget with an extremely high accuracy has been widely recognized but has never been formulated in the framework of fundamental physics. In this paper we give a first-principles definition of the planetary electromagnetic-energy budget using the Poynting-vector formalism and discuss how it can, in principle, be measured. Our derivation is based on an absolute minimum of theoretical assumptions, is free of outdated notions of phenomenological radiometry, and naturally leads to the conceptual formulation of an instrument called the double hemispherical cavity radiometer (DHCR). The practical measurement of the planetary energy budget would require flying a constellation of several dozen planet-orbiting satellites hosting identical well-calibrated DHCRs.

First-principles definition and measurement of planetary electromagnetic-energy budget

NASA Astrophysics Data System (ADS)

Mishchenko, M. I.; James, L.; Lacis, A. A.; Travis, L. D.; Cairns, B.

2016-12-01

The imperative to quantify the Earth's electromagnetic-energy budget with an extremely high accuracy has been widely recognized but has never been formulated in the framework of fundamental physics. In this talk we give a first-principles definition of the planetary electromagnetic-energy budget using the Poynting-vector formalism and discuss how it can, in principle, be measured. Our derivation is based on an absolute minimum of theoretical assumptions, is free of outdated concepts of phenomenological radiometry, and naturally leads to the conceptual formulation of an instrument called the double hemispherical cavity radiometer (DHCR). The practical measurement of the planetary energy budget would require flying a constellation of several dozen planet-orbiting satellites hosting identical well-calibrated DHCRs.

First-Principles Definition and Measurement of Planetary Electromagnetic-Energy Budget

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Lock, James A.; Lacis, Andrew A.; Travis, Larry D.; Cairns, Brian

2016-01-01

The imperative to quantify the Earths electromagnetic-energy budget with an extremely high accuracy has been widely recognized but has never been formulated in the framework of fundamental physics. In this paper we give a first-principles definition of the planetary electromagnetic-energy budget using the Poynting- vector formalism and discuss how it can, in principle, be measured. Our derivation is based on an absolute minimum of theoretical assumptions, is free of outdated notions of phenomenological radiometry, and naturally leads to the conceptual formulation of an instrument called the double hemispherical cavity radiometer (DHCR). The practical measurement of the planetary energy budget would require flying a constellation of several dozen planet-orbiting satellites hosting identical well-calibrated DHCRs.

Accurate atomistic first-principles calculations of electronic stopping

DOE PAGES

Schleife, André; Kanai, Yosuke; Correa, Alfredo A.

2015-01-20

In this paper, we show that atomistic first-principles calculations based on real-time propagation within time-dependent density functional theory are capable of accurately describing electronic stopping of light projectile atoms in metal hosts over a wide range of projectile velocities. In particular, we employ a plane-wave pseudopotential scheme to solve time-dependent Kohn-Sham equations for representative systems of H and He projectiles in crystalline aluminum. This approach to simulate nonadiabatic electron-ion interaction provides an accurate framework that allows for quantitative comparison with experiment without introducing ad hoc parameters such as effective charges, or assumptions about the dielectric function. Finally, our work clearlymore » shows that this atomistic first-principles description of electronic stopping is able to disentangle contributions due to tightly bound semicore electrons and geometric aspects of the stopping geometry (channeling versus off-channeling) in a wide range of projectile velocities.« less

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles.

PubMed

Fang, Teng; Zhao, Xinbing; Zhu, Tiejun

2018-05-19

Half-Heusler (HH) compounds, with a valence electron count of 8 or 18, have gained popularity as promising high-temperature thermoelectric (TE) materials due to their excellent electrical properties, robust mechanical capabilities, and good high-temperature thermal stability. With the help of first-principles calculations, great progress has been made in half-Heusler thermoelectric materials. In this review, we summarize some representative theoretical work on band structures and transport properties of HH compounds. We introduce how basic band-structure calculations are used to investigate the atomic disorder in n-type M NiSb ( M = Ti, Zr, Hf) compounds and guide the band engineering to enhance TE performance in p-type Fe R Sb ( R = V, Nb) based systems. The calculations on electrical transport properties, especially the scattering time, and lattice thermal conductivities are also demonstrated. The outlook for future research directions of first-principles calculations on HH TE materials is also discussed.

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles

PubMed Central

Fang, Teng; Zhao, Xinbing

2018-01-01

Half-Heusler (HH) compounds, with a valence electron count of 8 or 18, have gained popularity as promising high-temperature thermoelectric (TE) materials due to their excellent electrical properties, robust mechanical capabilities, and good high-temperature thermal stability. With the help of first-principles calculations, great progress has been made in half-Heusler thermoelectric materials. In this review, we summarize some representative theoretical work on band structures and transport properties of HH compounds. We introduce how basic band-structure calculations are used to investigate the atomic disorder in n-type MNiSb (M = Ti, Zr, Hf) compounds and guide the band engineering to enhance TE performance in p-type FeRSb (R = V, Nb) based systems. The calculations on electrical transport properties, especially the scattering time, and lattice thermal conductivities are also demonstrated. The outlook for future research directions of first-principles calculations on HH TE materials is also discussed. PMID:29783759

Origin of spin reorientation transitions in antiferromagnetic MnPt-based alloys

NASA Astrophysics Data System (ADS)

Chang, P.-H.; Zhuravlev, I. A.; Belashchenko, K. D.

2018-04-01

Antiferromagnetic MnPt exhibits a spin reorientation transition (SRT) as a function of temperature, and off-stoichiometric Mn-Pt alloys also display SRTs as a function of concentration. The magnetocrystalline anisotropy in these alloys is studied using first-principles calculations based on the coherent potential approximation and the disordered local moment method. The anisotropy is fairly small and sensitive to the variations in composition and temperature due to the cancellation of large contributions from different parts of the Brillouin zone. Concentration and temperature-driven SRTs are found in reasonable agreement with experimental data. Contributions from specific band-structure features are identified and used to explain the origin of the SRTs.

Deep Potential Molecular Dynamics: A Scalable Model with the Accuracy of Quantum Mechanics

NASA Astrophysics Data System (ADS)

Zhang, Linfeng; Han, Jiequn; Wang, Han; Car, Roberto; E, Weinan

2018-04-01

We introduce a scheme for molecular simulations, the deep potential molecular dynamics (DPMD) method, based on a many-body potential and interatomic forces generated by a carefully crafted deep neural network trained with ab initio data. The neural network model preserves all the natural symmetries in the problem. It is first-principles based in the sense that there are no ad hoc components aside from the network model. We show that the proposed scheme provides an efficient and accurate protocol in a variety of systems, including bulk materials and molecules. In all these cases, DPMD gives results that are essentially indistinguishable from the original data, at a cost that scales linearly with system size.

An exact algorithm for optimal MAE stack filter design.

PubMed

Dellamonica, Domingos; Silva, Paulo J S; Humes, Carlos; Hirata, Nina S T; Barrera, Junior

2007-02-01

We propose a new algorithm for optimal MAE stack filter design. It is based on three main ingredients. First, we show that the dual of the integer programming formulation of the filter design problem is a minimum cost network flow problem. Next, we present a decomposition principle that can be used to break this dual problem into smaller subproblems. Finally, we propose a specialization of the network Simplex algorithm based on column generation to solve these smaller subproblems. Using our method, we were able to efficiently solve instances of the filter problem with window size up to 25 pixels. To the best of our knowledge, this is the largest dimension for which this problem was ever solved exactly.

Delocalization of frontier orbitals induced red emission for heptazine based thermally activated delayed fluorescence molecule: First-principles study

NASA Astrophysics Data System (ADS)

Kang, Yongxiang; Zhao, Liyun; Leng, Jiancai

2018-04-01

Design of red organic emitting molecules with characteristic of thermally activated delayed fluorescence (TADF) remains a great challenge. Here, electronic and optical properties of a series of multi-branched TADF molecules have been investigated based on the newly-proposed optimal Hartree-Fock percentage method. Results show that, though enlarging the delocalization of HOMO and LUMO, the emission wavelength is redshift. The designed red TADF molecule possesses smaller reorganization energy than these for reported molecules. This indicates the non-radiative energy consumption of excited state is small and effective luminescence can be expected. Thus, a promising red thermally activated delayed fluorescence molecule is proposed.

The application analysis of the multi-angle polarization technique for ocean color remote sensing

NASA Astrophysics Data System (ADS)

Zhang, Yongchao; Zhu, Jun; Yin, Huan; Zhang, Keli

2017-02-01

The multi-angle polarization technique, which uses the intensity of polarized radiation as the observed quantity, is a new remote sensing means for earth observation. With this method, not only can the multi-angle light intensity data be provided, but also the multi-angle information of polarized radiation can be obtained. So, the technique may solve the problems, those could not be solved with the traditional remote sensing methods. Nowadays, the multi-angle polarization technique has become one of the hot topics in the field of the international quantitative research on remote sensing. In this paper, we firstly introduce the principles of the multi-angle polarization technique, then the situations of basic research and engineering applications are particularly summarized and analysed in 1) the peeled-off method of sun glitter based on polarization, 2) the ocean color remote sensing based on polarization, 3) oil spill detection using polarization technique, 4) the ocean aerosol monitoring based on polarization. Finally, based on the previous work, we briefly present the problems and prospects of the multi-angle polarization technique used in China's ocean color remote sensing.

An Improved SoC Test Scheduling Method Based on Simulated Annealing Algorithm

NASA Astrophysics Data System (ADS)

Zheng, Jingjing; Shen, Zhihang; Gao, Huaien; Chen, Bianna; Zheng, Weida; Xiong, Xiaoming

2017-02-01

In this paper, we propose an improved SoC test scheduling method based on simulated annealing algorithm (SA). It is our first to disorganize IP core assignment for each TAM to produce a new solution for SA, allocate TAM width for each TAM using greedy algorithm and calculate corresponding testing time. And accepting the core assignment according to the principle of simulated annealing algorithm and finally attain the optimum solution. Simultaneously, we run the test scheduling experiment with the international reference circuits provided by International Test Conference 2002(ITC’02) and the result shows that our algorithm is superior to the conventional integer linear programming algorithm (ILP), simulated annealing algorithm (SA) and genetic algorithm(GA). When TAM width reaches to 48,56 and 64, the testing time based on our algorithm is lesser than the classic methods and the optimization rates are 30.74%, 3.32%, 16.13% respectively. Moreover, the testing time based on our algorithm is very close to that of improved genetic algorithm (IGA), which is state-of-the-art at present.

Progress towards an effective model for FeSe from high-accuracy first-principles quantum Monte Carlo

NASA Astrophysics Data System (ADS)

Busemeyer, Brian; Wagner, Lucas K.

While the origin of superconductivity in the iron-based materials is still controversial, the proximity of the superconductivity to magnetic order is suggestive that magnetism may be important. Our previous work has suggested that first-principles Diffusion Monte Carlo (FN-DMC) can capture magnetic properties of iron-based superconductors that density functional theory (DFT) misses, but which are consistent with experiment. We report on the progress of efforts to find simple effective models consistent with the FN-DMC description of the low-lying Hilbert space of the iron-based superconductor, FeSe. We utilize a procedure outlined by Changlani et al.[1], which both produces parameter values and indications of whether the model is a good description of the first-principles Hamiltonian. Using this procedure, we evaluate several models of the magnetic part of the Hilbert space found in the literature, as well as the Hubbard model, and a spin-fermion model. We discuss which interaction parameters are important for this material, and how the material-specific properties give rise to these interactions. U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, Scientific Discovery through Advanced Computing (SciDAC) program under Award No. FG02-12ER46875, as well as the NSF Graduate Research Fellowship Program.

First principles investigation of heterogeneous catalysis on metal oxide surfaces

NASA Astrophysics Data System (ADS)

Ghoussoub, Mireille

Metal oxides possess unique electronic and structural properties that render them highly favourable for applications in heterogeneous catalysis. In this study, computational atomistic modelling based on Density Functional Theory was used to investigate the reduction of carbon dioxide over hydroxylated indium oxide nanoparticles, as well at the activation of methane over oxygen-covered bimetallic surfaces. The first study employed metadynamics-biased ab initio molecular dynamics to obtain the free energy surface of the various reaction steps at finite temperature. In the second study, the nudged elastic band method was used to probe the C-H activation mechanisms for different surface configurations. In both cases, activation energies, reaction energies, transition state structures, and charge analysis results are used to explain the underlying mechanistic pathways.

Consolidated principles for screening based on a systematic review and consensus process

PubMed Central

Hagens, Victoria; Chafe, Roger; Sullivan, Terrence; Rabeneck, Linda

2018-01-01

BACKGROUND: In 1968, Wilson and Jungner published 10 principles of screening that often represent the de facto starting point for screening decisions today; 50 years on, are these principles still the right ones? Our objectives were to review published work that presents principles for population-based screening decisions since Wilson and Jungner’s seminal publication, and to conduct a Delphi consensus process to assess the review results. METHODS: We conducted a systematic review and modified Delphi consensus process. We searched multiple databases for articles published in English in 1968 or later that were intended to guide population-based screening decisions, described development and modification of principles, and presented principles as a set or list. Identified sets were compared for basic characteristics (e.g., number, categorization), a citation analysis was conducted, and principles were iteratively synthesized and consolidated into categories to assess evolution. Participants in the consensus process assessed the level of agreement with the importance and interpretability of the consolidated screening principles. RESULTS: We identified 41 sets and 367 unique principles. Each unique principle was coded to 12 consolidated decision principles that were further categorized as disease/condition, test/intervention or program/system principles. Program or system issues were the focus of 3 of Wilson and Jungner’s 10 principles, but comprised almost half of all unique principles identified in the review. The 12 consolidated principles were assessed through 2 rounds of the consensus process, leading to specific refinements to improve their relevance and interpretability. No gaps or missing principles were identified. INTERPRETATION: Wilson and Jungner’s principles are remarkably enduring, but increasingly reflect a truncated version of contemporary thinking on screening that does not fully capture subsequent focus on program or system principles. Ultimately, this review and consensus process provides a comprehensive and iterative modernization of guidance to inform population-based screening decisions. PMID:29632037

First principles and experimental study of the electronic structure and phase stability of bulk thallium bromide

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Zhou, Yuzhi; Ciampi, Guido; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Haller, E. E.; Chrzan, D. C.

2013-08-01

We apply state-of-art first principle calculations to study the polymorphism and electronic structure of three previously reported phases of TlBr. The calculated band structures of NaCl-structure phase and orthorhombic-structure phase have different features than that of commonly observed CsCl-structure phase. We further interpret photoluminescence spectra based on our calculations. Several peaks close to calculated band gap values of the NaCl-structure phase and the orthorhombic-structure phase are found in unpolished TlBr samples.

First-principles molecular transport calculation for the benzenedithiolate molecule

NASA Astrophysics Data System (ADS)

Rumetshofer, M.; Dorn, G.; Boeri, L.; Arrigoni, E.; von der Linden, W.

2017-10-01

A first-principles approach based on density functional theory and non-equilibrium Green’s functions is used to study the molecular transport system consisting of benzenedithiolate connected with monoatomic gold and platinum electrodes. Using symmetry arguments we explain why the conductance mechanism is different for gold and platinum electrodes. We present the charge stability diagram for the benzenedithiolate connected with monoatomic platinum electrodes including many-body effects in terms of an extended Hubbard Hamiltonian and discuss how the electrodes and the many-body effects influence the transport properties of the system.

First-principles studies on the equation-of-state, thermal-conductivity, and opacity of deuterium-tritium and polystyrene (CH) for inertial confinement fusion applications

DOE PAGES

Hu, Suxing; Collins, Lee A.; Goncharov, V. N.; ...

2016-05-26

Using first-principles (FP) methods, we have performed ab initio compute for the equation of state (EOS), thermal conductivity, and opacity of deuterium-tritium (DT) in a wide range of densities and temperatures for inertial confinement fusion (ICF) applications. These systematic investigations have recently been expanded to accurately compute the plasma properties of CH ablators under extreme conditions. In particular, the first-principles EOS and thermal-conductivity tables of CH are self-consistently built from such FP calculations, which are benchmarked by experimental measurements. When compared with the traditional models used for these plasma properties in hydrocodes, significant differences have been identified in the warmmore » dense plasma regime. When these FP-calculated properties of DT and CH were used in our hydrodynamic simulations of ICF implosions, we found that the target performance in terms of neutron yield and energy gain can vary by a factor of 2 to 3, relative to traditional model simulations.« less

Polarization-dependent force driving the Eg mode in bismuth under optical excitation: comparison of first-principles theory with ultra-fast x-ray experiments

NASA Astrophysics Data System (ADS)

Fahy, Stephen; Murray, Eamonn

2015-03-01

Using first principles electronic structure methods, we calculate the induced force on the Eg (zone centre transverse optical) phonon mode in bismuth immediately after absorption of a ultrafast pulse of polarized light. To compare the results with recent ultra-fast, time-resolved x-ray diffraction experiments, we include the decay of the force due to carrier scattering, as measured in optical Raman scattering experiments, and simulate the optical absorption process, depth-dependent atomic driving forces, and x-ray diffraction in the experimental geometry. We find excellent agreement between the theoretical predictions and the observed oscillations of the x-ray diffraction signal, indicating that first-principles theory of optical absorption is well suited to the calculation of initial atomic driving forces in photo-excited materials following ultrafast excitation. This work is supported by Science Foundation Ireland (Grant No. 12/IA/1601) and EU Commission under the Marie Curie Incoming International Fellowships (Grant No. PIIF-GA-2012-329695).

First principles molecular dynamics of metal/water interfaces under bias potential

NASA Astrophysics Data System (ADS)

Pedroza, Luana; Brandimarte, Pedro; Rocha, Alexandre; Fernandez-Serra, Marivi

2014-03-01

Understanding the interaction of the water-metal system at an atomic level is extremely important in electrocatalysts for fuel cells, photocatalysis among other systems. The question of the interface energetics involves a detailed study of the nature of the interactions between water-water and water-substrate. A first principles description of all components of the system is the most appropriate methodology in order to advance understanding of electrochemically processes. In this work we describe, using first principles molecular dynamics simulations, the dynamics of a combined surface(Au and Pd)/water system both in the presence and absence of an external bias potential applied to the electrodes, as one would come across in electrochemistry. This is accomplished using a combination of density functional theory (DFT) and non-equilibrium Green's functions methods (NEGF), thus accounting for the fact that one is dealing with an out-of-equilibrium open system, with and without van der Waals interactions. DOE Early Career Award No. DE-SC0003871.

The Bayesian approach to reporting GSR analysis results: some first-hand experiences

NASA Astrophysics Data System (ADS)

Charles, Sebastien; Nys, Bart

2010-06-01

The use of Bayesian principles in the reporting of forensic findings has been a matter of interest for some years. Recently, also the GSR community is gradually exploring the advantages of this method, or rather approach, for writing reports. Since last year, our GSR group is adapting reporting procedures to the use of Bayesian principles. The police and magistrates find the reports more directly accessible and useful in their part of the criminal investigation. In the lab we find that, through applying the Bayesian principles, unnecessary analyses can be eliminated and thus time can be freed on the instruments.

Extraction Method and Analysis of Cannabinoids in Cannabis Olive Oil Preparations.

PubMed

Casiraghi, Antonella; Roda, Gabriella; Casagni, Eleonora; Cristina, Cecilia; Musazzi, Umberto Maria; Franzè, Silvia; Rocco, Paolo; Giuliani, Claudia; Fico, Gelsomina; Minghetti, Paola; Gambaro, Veniero

2018-03-01

Recently, an increasing number of pharmacists had to supply medicinal products based on Cannabis sativa L. (Cannabaceae), prescribed by physicians to individual patients. Cannabis olive oil preparation is the first choice as a concentrated extract of cannabinoids, even though standardized operative conditions for obtaining it are still not available. In this work, the impact of temperature and extraction time on the concentration of active principles was studied to harmonize the different compounding methods, optimize the extraction process, and reduce the variability among preparations. Moreover, starting from the cannabis inflorescence, the effect of temperature on tetrahydrocannabinolic acid decarboxylation was evaluated. For the analysis, a GC/MS method, as suggested by the Italian Ministry of Health, and a GC/flame ionization detection method were developed, validated, and compared. Georg Thieme Verlag KG Stuttgart · New York.

Incorporating café design principles into End-of-Life discussions: an innovative method for continuing education.

PubMed

Kanaskie, Mary Louise

2011-04-01

Café design provides an innovative method for conducting continuing education activities. This method was chosen to elicit meaningful conversation based on issues related to End-of-Life care. Café design principles incorporate the following: setting the context, creating hospitable space, exploring questions that matter, encouraging everyone's contributions, connecting diverse perspectives, listening together for insights, and sharing collective discoveries. Key discussion questions were identified from the End-of Life Nursing Education Consortium Core Curriculum. Questions were revised to incorporate the principles of appreciative inquiry, which encourage a shift from traditional methods of problem identification to creation of a positive vision. Participants rated the café design method as an effective way to share their ideas and to stimulate conversation.

Experimental and first principle study of the structure, electronic, optical and luminescence properties of M-type GdNbO4 phosphor

NASA Astrophysics Data System (ADS)

Ding, Shoujun; Zhang, Haotian; Zhang, Qingli; Chen, Yuanzhi; Dou, Renqin; Peng, Fang; Liu, Wenpeng; Sun, Dunlu

2018-06-01

In this work, GdNbO4 polycrystalline with monoclinic phase was prepared by traditional high-temperature solid-state reaction. Its structure was determined by X-ray diffraction and its unit cell parameters were obtained with Rietveld refinement method. Its luminescence properties (including absorbance, emission and luminescence lifetime) were investigated with experiment method and the CIE chromaticity coordinate was presented. Furthermore, a systematic theoretical calculation (including band gap, density of states and optical properties) based on the density function theory methods was performed on GdNbO4. Lastly, a comparison between experiment and calculated results was conducted. The calculated and experiment results obtained in this work can provide an essential understanding of GdNbO4 material.

Will the 'principles of effectiveness' improve prevention practice? Early findings from a diffusion study.

PubMed

Hallfors, D; Godette, D

2002-08-01

This study examines adoption and implementation of the US Department of Education's new policy, the 'Principles of Effectiveness', from a diffusion of innovations theoretical framework. In this report, we evaluate adoption in relation to Principle 3: the requirement to select research-based programs. Results from a sample of 104 school districts in 12 states indicate that many districts appear to be selecting research-based curricula, but that the quality of implementation is low. Only 19% of the responding district coordinators indicated that schools were implementing a research-based curriculum with fidelity. Common problems included lack of teacher training, lack of requisite materials, use of some but not all of the required lessons and teaching strategies, and failure to deliver lessons to age-appropriate student groups. This study represents the first attempt to assess the quality of implementation of research-based programs as required by the Principles of Effectiveness. We conclude that low levels of funding, inadequate infrastructure, decentralized decision making and lack of program guidance have contributed to the slow progress in improving school-based prevention.

Nanomaterials-based biosensors for detection of microorganisms and microbial toxins.

PubMed

Sutarlie, Laura; Ow, Sian Yang; Su, Xiaodi

2017-04-01

Detection of microorganisms and microbial toxins is important for health and safety. Due to their unique physical and chemical properties, nanomaterials have been extensively used to develop biosensors for rapid detection of microorganisms with microbial cells and toxins as target analytes. In this paper, the design principles of nanomaterials-based biosensors for four selected analyte categories (bacteria cells, toxins, mycotoxins, and protozoa cells), closely associated with the target analytes' properties is reviewed. Five signal transducing methods that are less equipment intensive (colorimetric, fluorimetric, surface enhanced Raman scattering, electrochemical, and magnetic relaxometry methods) is described and compared for their sensory performance (in term oflimit of detection, dynamic range, and response time) for all analyte categories. In the end, the suitability of these five sensing principles for on-site or field applications is discussed. With a comprehensive coverage of nanomaterials, design principles, sensing principles, and assessment on the sensory performance and suitability for on-site application, this review offers valuable insight and perspective for designing suitable nanomaterials-based microorganism biosensors for a given application. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Study of cubic boron nitride crystal UV absorption spectroscopy].

PubMed

Liu, Hai-Bo; Jia, Gang; Chen, Gang; Meng, Qing-Ju; Zhang, Tie-Chen

2008-07-01

UV absorption spectroscopy of artificial cubic boron nitride (cBN) single crystal flake, synthesized under high-temperature and high-pressure, was studied in the present paper. UV WINLAB spectrometer was used in the experiments, and MOLECULAR SPECTROSCOPY software was used for data analysis. The UV-cBN limit of 198 nm was showed in this test by a special fixture quartz sample. We calculated the energy gap by virtue of the formula: lambda0 = 1.24/E(g) (microm). The energy gap is 6. 26 eV. There are many viewpoints about the gap of cBN. By using the first-principles theory to calculate energy band structure and density of electronic states of cBN, an indirect transition due to electronics in valence band jumping into conduction band by absorbing photon can be confirmed. That leads to UV absorption. The method of calculation was based on the quantum mechanics of CASTEP in the commercial software package of Cerius2 in the Co. Accerlrys in the United States. The theory of CASTEP is based on local density approximation or gradient corrected LDA. The crystal parameter of cBN was input to the quantum mechanics of CASTEP in order to construct the crystal parameter model of cBN. We calculated the energy gap of cBN by the method of gradient corrected LDA. The method underestimates the value of nonconductor by about 1 to 2 eV. We gaot some opinions as follows: cBN is indirect band semiconductor. The energy gap is 4.76 eV, less than our experiment. The reason may be defect that we ignored in calculating process. It was reported that the results by first principles method of calculation of the band generally was less than the experimental results. This paper shows good UV characteristics of cBN because of the good agreement of experimental results with the cBN band width. That is a kind of development prospect of UV photo-electronic devices and high-temperature semiconductor devices.

Quantification of uncertainty in first-principles predicted mechanical properties of solids: Application to solid ion conductors

NASA Astrophysics Data System (ADS)

Ahmad, Zeeshan; Viswanathan, Venkatasubramanian

2016-08-01

Computationally-guided material discovery is being increasingly employed using a descriptor-based screening through the calculation of a few properties of interest. A precise understanding of the uncertainty associated with first-principles density functional theory calculated property values is important for the success of descriptor-based screening. The Bayesian error estimation approach has been built in to several recently developed exchange-correlation functionals, which allows an estimate of the uncertainty associated with properties related to the ground state energy, for example, adsorption energies. Here, we propose a robust and computationally efficient method for quantifying uncertainty in mechanical properties, which depend on the derivatives of the energy. The procedure involves calculating energies around the equilibrium cell volume with different strains and fitting the obtained energies to the corresponding energy-strain relationship. At each strain, we use instead of a single energy, an ensemble of energies, giving us an ensemble of fits and thereby, an ensemble of mechanical properties associated with each fit, whose spread can be used to quantify its uncertainty. The generation of ensemble of energies is only a post-processing step involving a perturbation of parameters of the exchange-correlation functional and solving for the energy non-self-consistently. The proposed method is computationally efficient and provides a more robust uncertainty estimate compared to the approach of self-consistent calculations employing several different exchange-correlation functionals. We demonstrate the method by calculating the uncertainty bounds for several materials belonging to different classes and having different structures using the developed method. We show that the calculated uncertainty bounds the property values obtained using three different GGA functionals: PBE, PBEsol, and RPBE. Finally, we apply the approach to calculate the uncertainty associated with the DFT-calculated elastic properties of solid state Li-ion and Na-ion conductors.

Application of Problem Based Learning ((PBL) in a Course on Financial Accounting Principles

ERIC Educational Resources Information Center

Manaf, Nor Aziah Abdul; Ishak, Zuaini; Hussin, Wan Nordin Wan

2011-01-01

Purpose: This paper aims to share experiences in teaching a Financial Accounting Principles course using a hybrid problem based learning (PBL) method. The three specific objectives of this paper are to document how the PBL project for this course was developed and managed in class, to compare the academic performance of PBL students with non-PBL…

Food Safety Programs Based on HACCP Principles in School Nutrition Programs: Implementation Status and Factors Related to Implementation

ERIC Educational Resources Information Center

Stinson, Wendy Bounds; Carr, Deborah; Nettles, Mary Frances; Johnson, James T.

2011-01-01

Purpose/Objectives: The objectives of this study were to assess the extent to which school nutrition (SN) programs have implemented food safety programs based on Hazard Analysis and Critical Control Point (HACCP) principles, as well as factors, barriers, and practices related to implementation of these programs. Methods: An online survey was…

First-Principles Modeling of Hydrogen Storage in Metal Hydride Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Karl Johnson

The objective of this project is to complement experimental efforts of MHoCE partners by using state-of-the-art theory and modeling to study the structure, thermodynamics, and kinetics of hydrogen storage materials. Specific goals include prediction of the heats of formation and other thermodynamic properties of alloys from first principles methods, identification of new alloys that can be tested experimentally, calculation of surface and energetic properties of nanoparticles, and calculation of kinetics involved with hydrogenation and dehydrogenation processes. Discovery of new metal hydrides with enhanced properties compared with existing materials is a critical need for the Metal Hydride Center of Excellence. Newmore » materials discovery can be aided by the use of first principles (ab initio) computational modeling in two ways: (1) The properties, including mechanisms, of existing materials can be better elucidated through a combined modeling/experimental approach. (2) The thermodynamic properties of novel materials that have not been made can, in many cases, be quickly screened with ab initio methods. We have used state-of-the-art computational techniques to explore millions of possible reaction conditions consisting of different element spaces, compositions, and temperatures. We have identified potentially promising single- and multi-step reactions that can be explored experimentally.« less

Evaluating effective pair and multisite interactions for Ni-Mo system

NASA Astrophysics Data System (ADS)

Banerjee, Rumu H.; Arya, A.; Banerjee, S.

2018-04-01

Cluster expansion (CE) method was used to calculate the energies of various Ni-Mo phases. The clusters comprising of few nearest neighbours can describe any phase of Ni-Mo system by suitable choice of effective pair and multisite interaction parameters (ECI). The ECIs were evaluated in present study by fitting the ground state energies obtained by first principle calculations. The ECIs evaluated for Ni-Mo system were mostly pair clusters followed by triplets and quadruplet clusters with cluster diameters in the range 2.54 - 10.20 Å. The ECI values diminished for multi-body (triplets and quadruplets) clusters as compared to 2-point or pair clusters indicating a good convergence of CE model. With these ECIs the predicted energies of all the Ni-Mo structures across the Mo concentration range 0-100 at% were obtained. The quantitative error in the energies calculated by CE approach and first principle is very small (< 0.026 meV/atom). The appreciable values of 2-point ECIs upto 4th nearest neighbour reveal that two body interactions are dominant in the case of Ni-Mo system. These ECIs are compared with the reported values of compositional dependent effective pair interactions evaluated by first principle as well as by Monte Carlo method.

Towards an ab initio description of correlated materials

NASA Astrophysics Data System (ADS)

Yee, Chuck-Hou

Strongly-correlated materials are a rich playground for physical phenomena, exhibiting complex phase diagrams with many competing orders. Ab initio insights into materials combined with physical ideas provide the ability to identify the organizing principles driving the correlated electronic behavior and pursue first-principles design of new compounds. Realistic modeling of correlated materials is an active area of research, especially with the recent merger of density functional theory (DFT) with dynamical mean-field theory (DMFT). This thesis is structured in two parts. The first describes the methods and algorithmic developments which drive advances in DFT+DMFT. In Ch. 2 and 3, we provide an overview of the two foundational theories, DMFT and DFT. In the second half of Ch. 3, we describe some of the principles guiding the combination of the two theories to form DFT+DMFT. In Ch. 4, we describe the algorithm lying at the heart of modern DFT+DMFT implementations, the hybridization expansion formulation of continuous-time quantum monte carlo (CTQMC) for the general Anderson impurity problem, as well as a fast rejection algorithm for speeding-up the local trace evaluation. The final chapter in the methods section describes an algorithm for direct sampling of the partition function, and thus the free energy and entropy, of simple Anderson impurity models within CTQMC. The second part of the thesis is a collection of applications of our ab initio approach to key correlated materials. We first apply our method to plutonium binary alloys (Ch. 6), which when supplemented with slave-boson mean-field theory, allows us to understand the observed photoemission spectra. Ch. 7 describes the computation of spectra and optical conductivity for rare-earth nickelates grown as epitaxial thin films. In the final two chapters, we turn our attention to the high-temperature superconductors. In the first, we show that the charge-transfer energy is a key chemical variable which controls the superconducting transition temperatures across the cuprate families. In the second, we extend this idea towards first-principles design of cuprates by exploring a new family of copper oxysulfides.

Fragment-Based Electronic Structure Approach for Computing Nuclear Magnetic Resonance Chemical Shifts in Molecular Crystals.

PubMed

Hartman, Joshua D; Beran, Gregory J O

2014-11-11

First-principles chemical shielding tensor predictions play a critical role in studying molecular crystal structures using nuclear magnetic resonance. Fragment-based electronic structure methods have dramatically improved the ability to model molecular crystal structures and energetics using high-level electronic structure methods. Here, a many-body expansion fragment approach is applied to the calculation of chemical shielding tensors in molecular crystals. First, the impact of truncating the many-body expansion at different orders and the role of electrostatic embedding are examined on a series of molecular clusters extracted from molecular crystals. Second, the ability of these techniques to assign three polymorphic forms of the drug sulfanilamide to the corresponding experimental (13)C spectra is assessed. This challenging example requires discriminating among spectra whose (13)C chemical shifts differ by only a few parts per million (ppm) across the different polymorphs. Fragment-based PBE0/6-311+G(2d,p) level chemical shielding predictions correctly assign these three polymorphs and reproduce the sulfanilamide experimental (13)C chemical shifts with 1 ppm accuracy. The results demonstrate that fragment approaches are competitive with the widely used gauge-invariant projector augmented wave (GIPAW) periodic density functional theory calculations.

Thermodynamics of concentrated solid solution alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Michael C.; Zhang, C.; Gao, P.

This study reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation drivingmore » force plots of the σ phase using CALPHAD method. The temperature-dependent total entropies of the FCC, BCC, HCP, and σ phases in equimolar compositions of various systems are presented next, followed by the thermodynamic properties of mixing of the BCC phase in Al-containing and Ti-containing refractory metal systems. First-principles calculations on model FCC, BCC and HCP CSSA reveal the presence of both positive and negative vibrational entropies of mixing, while the calculated electronic entropies of mixing are negligible. Temperature dependent configurational entropy is determined from the atomic structures obtained from MC/MD simulations. Current status and challenges in using these methodologies as they pertain to thermodynamic property analysis and CSSA design are discussed.« less

Thermodynamics of concentrated solid solution alloys

DOE PAGES

Gao, Michael C.; Zhang, C.; Gao, P.; ...

2017-10-12

This study reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation drivingmore » force plots of the σ phase using CALPHAD method. The temperature-dependent total entropies of the FCC, BCC, HCP, and σ phases in equimolar compositions of various systems are presented next, followed by the thermodynamic properties of mixing of the BCC phase in Al-containing and Ti-containing refractory metal systems. First-principles calculations on model FCC, BCC and HCP CSSA reveal the presence of both positive and negative vibrational entropies of mixing, while the calculated electronic entropies of mixing are negligible. Temperature dependent configurational entropy is determined from the atomic structures obtained from MC/MD simulations. Current status and challenges in using these methodologies as they pertain to thermodynamic property analysis and CSSA design are discussed.« less

First-principles modeling of quantum nuclear effects and atomic interactions in solid 4He at high pressure

NASA Astrophysics Data System (ADS)

Cazorla, Claudio; Boronat, Jordi

2015-01-01

We present a first-principles computational study of solid 4He at T =0 K and pressures up to ˜160 GPa. Our computational strategy consists in using van der Waals density functional theory (DFT-vdW) to describe the electronic degrees of freedom in this material, and the diffusion Monte Carlo (DMC) method to solve the Schrödinger equation describing the behavior of the quantum nuclei. For this, we construct an analytical interaction function based on the pairwise Aziz potential that closely matches the volume variation of the cohesive energy calculated with DFT-vdW in dense helium. Interestingly, we find that the kinetic energy of solid 4He does not increase appreciably with compression for P ≥85 GPa. Also, we show that the Lindemann ratio in dense solid 4He amounts to 0.10 almost independently of pressure. The reliability of customary quasiharmonic DFT (QH DFT) approaches in describing quantum nuclear effects in solids is also studied. We find that QH DFT simulations, although provide a reasonable equation of state in agreement with experiments, are not able to reproduce correctly these critical effects in compressed 4He. In particular, we disclose huge discrepancies of at least ˜50 % in the calculated 4He kinetic energies using both the QH DFT and present DFT-DMC methods.

Separation and sorting of cells in microsystems using physical principles

NASA Astrophysics Data System (ADS)

Lee, Gi-Hun; Kim, Sung-Hwan; Ahn, Kihoon; Lee, Sang-Hoon; Park, Joong Yull

2016-01-01

In the last decade, microfabrication techniques have been combined with microfluidics and applied to cell biology. Utilizing such new techniques, various cell studies have been performed for the research of stem cells, immune cells, cancer, neurons, etc. Among the various biological applications of microtechnology-based platforms, cell separation technology has been highly regarded in biological and clinical fields for sorting different types of cells, finding circulating tumor cells (CTCs), and blood cell separation, amongst other things. Many cell separation methods have been created using various physical principles. Representatively, these include hydrodynamic, acoustic, dielectrophoretic, magnetic, optical, and filtering methods. In this review, each of these methods will be introduced, and their physical principles and sample applications described. Each physical principle has its own advantages and disadvantages. The engineers who design the systems and the biologists who use them should understand the pros and cons of each method or principle, to broaden the use of microsystems for cell separation. Continuous development of microsystems for cell separation will lead to new opportunities for diagnosing CTCs and cancer metastasis, as well as other elements in the bloodstream.

On hydrostatic flows in isentropic coordinates

NASA Astrophysics Data System (ADS)

Bokhove, Onno

2000-01-01

The hydrostatic primitive equations of motion which have been used in large-scale weather prediction and climate modelling over the last few decades are analysed with variational methods in an isentropic Eulerian framework. The use of material isentropic coordinates for the Eulerian hydrostatic equations is known to have distinct conceptual advantages since fluid motion is, under inviscid and statically stable circumstances, confined to take place on quasi-horizontal isentropic surfaces. First, an Eulerian isentropic Hamilton's principle, expressed in terms of fluid parcel variables, is therefore derived by transformation of a Lagrangian Hamilton's principle to an Eulerian one. This Eulerian principle explicitly describes the boundary dynamics of the time-dependent domain in terms of advection of boundary isentropes sB; these are the values the isentropes have at their intersection with the (lower) boundary. A partial Legendre transform for only the interior variables yields an Eulerian ‘action’ principle. Secondly, Noether's theorem is used to derive energy and potential vorticity conservation from the Eulerian Hamilton's principle. Thirdly, these conservation laws are used to derive a wave-activity invariant which is second-order in terms of small-amplitude disturbances relative to a resting or moving basic state. Linear stability criteria are derived but only for resting basic states. In mid-latitudes a time- scale separation between gravity and vortical modes occurs. Finally, this time-scale separation suggests that conservative geostrophic and ageostrophic approximations can be made to the Eulerian action principle for hydrostatic flows. Approximations to Eulerian variational principles may be more advantageous than approximations to Lagrangian ones because non-dimensionalization and scaling tend to be based on Eulerian estimates of the characteristic scales involved. These approximations to the stratified hydrostatic formulation extend previous approximations to the shallow- water equations. An explicit variational derivation is given of an isentropic version of Hoskins & Bretherton's model for atmospheric fronts.

Life is determined by its environment

NASA Astrophysics Data System (ADS)

Torday, John S.; Miller, William B.

2016-10-01

A well-developed theory of evolutionary biology requires understanding of the origins of life on Earth. However, the initial conditions (ontology) and causal (epistemology) bases on which physiology proceeded have more recently been called into question, given the teleologic nature of Darwinian evolutionary thinking. When evolutionary development is focused on cellular communication, a distinctly different perspective unfolds. The cellular communicative-molecular approach affords a logical progression for the evolutionary narrative based on the basic physiologic properties of the cell. Critical to this appraisal is recognition of the cell as a fundamental reiterative unit of reciprocating communication that receives information from and reacts to epiphenomena to solve problems. Following the course of vertebrate physiology from its unicellular origins instead of its overt phenotypic appearances and functional associations provides a robust, predictive picture for the means by which complex physiology evolved from unicellular organisms. With this foreknowledge of physiologic principles, we can determine the fundamentals of Physiology based on cellular first principles using a logical, predictable method. Thus, evolutionary creativity on our planet can be viewed as a paradoxical product of boundary conditions that permit homeostatic moments of varying length and amplitude that can productively absorb a variety of epigenetic impacts to meet environmental challenges.

The image recognition based on neural network and Bayesian decision

NASA Astrophysics Data System (ADS)

Wang, Chugege

2018-04-01

The artificial neural network began in 1940, which is an important part of artificial intelligence. At present, it has become a hot topic in the fields of neuroscience, computer science, brain science, mathematics, and psychology. Thomas Bayes firstly reported the Bayesian theory in 1763. After the development in the twentieth century, it has been widespread in all areas of statistics. In recent years, due to the solution of the problem of high-dimensional integral calculation, Bayesian Statistics has been improved theoretically, which solved many problems that cannot be solved by classical statistics and is also applied to the interdisciplinary fields. In this paper, the related concepts and principles of the artificial neural network are introduced. It also summarizes the basic content and principle of Bayesian Statistics, and combines the artificial neural network technology and Bayesian decision theory and implement them in all aspects of image recognition, such as enhanced face detection method based on neural network and Bayesian decision, as well as the image classification based on the Bayesian decision. It can be seen that the combination of artificial intelligence and statistical algorithms has always been the hot research topic.

Life is determined by its environment

PubMed Central

Torday, John S.; Miller, William B.

2016-01-01

A well-developed theory of evolutionary biology requires understanding of the origins of life on Earth. However, the initial conditions (ontology) and causal (epistemology) bases on which physiology proceeded have more recently been called into question, given the teleologic nature of Darwinian evolutionary thinking. When evolutionary development is focused on cellular communication, a distinctly different perspective unfolds. The cellular communicative-molecular approach affords a logical progression for the evolutionary narrative based on the basic physiologic properties of the cell. Critical to this appraisal is recognition of the cell as a fundamental reiterative unit of reciprocating communication that receives information from and reacts to epiphenomena to solve problems. Following the course of vertebrate physiology from its unicellular origins instead of its overt phenotypic appearances and functional associations provides a robust, predictive picture for the means by which complex physiology evolved from unicellular organisms. With this foreknowledge of physiologic principles, we can determine the fundamentals of Physiology based on cellular first principles using a logical, predictable method. Thus, evolutionary creativity on our planet can be viewed as a paradoxical product of boundary conditions that permit homeostatic moments of varying length and amplitude that can productively absorb a variety of epigenetic impacts to meet environmental challenges. PMID:27708547

Research to Assembly Scheme for Satellite Deck Based on Robot Flexibility Control Principle

NASA Astrophysics Data System (ADS)

Guo, Tao; Hu, Ruiqin; Xiao, Zhengyi; Zhao, Jingjing; Fang, Zhikai

2018-03-01

Deck assembly is critical quality control point in final satellite assembly process, and cable extrusion and structure collision problems in assembly process will affect development quality and progress of satellite directly. Aimed at problems existing in deck assembly process, assembly project scheme for satellite deck based on robot flexibility control principle is proposed in this paper. Scheme is introduced firstly; secondly, key technologies on end force perception and flexible docking control in the scheme are studied; then, implementation process of assembly scheme for satellite deck is described in detail; finally, actual application case of assembly scheme is given. Result shows that compared with traditional assembly scheme, assembly scheme for satellite deck based on robot flexibility control principle has obvious advantages in work efficiency, reliability and universality aspects etc.

Coupled fluid-structure interaction. Part 1: Theory. Part 2: Application

NASA Technical Reports Server (NTRS)

Felippa, Carlos A.; Ohayon, Roger

1991-01-01

A general three dimensional variational principle is obtained for the motion of an acoustic field enclosed in a rigid or flexible container by the method of canonical decomposition applied to a modified form of the wave equation in the displacement potential. The general principle is specialized to a mixed two-field principle that contains the fluid displacement potential and pressure as independent fields. Semidiscrete finite element equations of motion based on this principle are derived and sample cases are given.

Redistribution Principle Approach for Evaluation of Seismic Active Earth Pressure Behind Retaining Wall

NASA Astrophysics Data System (ADS)

Maskar, A. D.; Madhekar, S. N.; Phatak, D. R.

2017-11-01

The knowledge of seismic active earth pressure behind the rigid retaining wall is very essential in the design of retaining wall in earthquake prone regions. Commonly used Mononobe-Okabe (MO) method considers pseudo-static approach. Recently there are many pseudo-dynamic methods used to evaluate the seismic earth pressure. However, available pseudo-static and pseudo-dynamic methods do not incorporate the effect of wall movement on the earth pressure distribution. Dubrova (Interaction between soils and structures, Rechnoi Transport, Moscow, 1963) was the first, who considered such effect and till date, it is used for cohesionless soil, without considering the effect of seismicity. In this paper, Dubrova's model based on redistribution principle, considering the seismic effect has been developed. It is further used to compute the distribution of seismic active earth pressure, in a more realistic manner, by considering the effect of wall movement on the earth pressure, as it is displacement based method. The effects of a wide range of parameters like soil friction angle (ϕ), wall friction angle (δ), horizontal and vertical seismic acceleration coefficients (kh and kv); on seismic active earth pressure (Kae) have been studied. Results are presented for comparison of pseudo-static and pseudo-dynamic methods, to highlight the realistic, non-linearity of seismic active earth pressure distribution. The current study results in the variation of Kae with kh in the same manner as that of MO method and Choudhury and Nimbalkar (Geotech Geol Eng 24(5):1103-1113, 2006) study. To increase in ϕ, there is a reduction in static as well as seismic earth pressure. Also, by keeping constant ϕ value, as kh increases from 0 to 0.3, earth pressure increases; whereas as δ increases, active earth pressure decreases. The seismic active earth pressure coefficient (Kae) obtained from the present study is approximately same as that obtained by previous researchers. Though seismic earth pressure obtained by pseudo-dynamic approach and seismic earth pressure obtained by redistribution principle have different background of formulation, the final earth pressure distribution is approximately same.

Rotational stellar structures based on the Lagrangian variational principle

NASA Astrophysics Data System (ADS)

Yasutake, Nobutoshi; Fujisawa, Kotaro; Yamada, Shoichi

2017-06-01

A new method for multi-dimensional stellar structures is proposed in this study. As for stellar evolution calculations, the Heney method is the defacto standard now, but basically assumed to be spherical symmetric. It is one of the difficulties for deformed stellar-evolution calculations to trace the potentially complex movements of each fluid element. On the other hand, our new method is very suitable to follow such movements, since it is based on the Lagrange coordinate. This scheme is also based on the variational principle, which is adopted to the studies for the pasta structures inside of neutron stars. Our scheme could be a major break through for evolution calculations of any types of deformed stars: proto-planets, proto-stars, and proto-neutron stars, etc.

TRIZ theory in NEA photocathode preparation system

NASA Astrophysics Data System (ADS)

Qiao, Jianliang; Huang, Dayong; Li, Xiangjiang; Gao, Youtang

2016-09-01

The solutions to the engineering problems were provided according to the innovation principle based on the theory of TRIZ. The ultra high vacuum test and evaluation system for the preparation of negative electron affinity (NEA) photocathode has the characteristics of complex structure and powerful functions. Segmentation principle, advance function principle, curved surface principle, dynamic characteristics principle and nested principle adopted by the design of ultra high vacuum test and evaluation system for cathode preparation were analyzed. The applications of the physical contradiction and the substance-field analysis method of the theory of TRIZ in the cathode preparation ultra high vacuum test and evaluation system were discussed.

Comparison of massage based on the tensegrity principle and classic massage in treating chronic shoulder pain.

PubMed

Kassolik, Krzysztof; Andrzejewski, Waldemar; Brzozowski, Marcin; Wilk, Iwona; Górecka-Midura, Lucyna; Ostrowska, Bożena; Krzyżanowski, Dominik; Kurpas, Donata

2013-09-01

The purpose of this study was to compare the clinical outcomes of classic massage to massage based on the tensegrity principle for patients with chronic idiopathic shoulder pain. Thirty subjects with chronic shoulder pain symptoms were divided into 2 groups, 15 subjects received classic (Swedish) massage to tissues surrounding the glenohumeral joint and 15 subjects received the massage using techniques based on the tensegrity principle. The tensegrity principle is based on directing treatment to the painful area and the tissues (muscles, fascia, and ligaments) that structurally support the painful area, thus treating tissues that have direct and indirect influence on the motion segment. Both treatment groups received 10 sessions over 2 weeks, each session lasted 20 minutes. The McGill Pain Questionnaire and glenohumeral ranges of motion were measured immediately before the first massage session, on the day the therapy ended 2 weeks after therapy started, and 1 month after the last massage. Subjects receiving massage based on the tensegrity principle demonstrated statistically significance improvement in the passive and active ranges of flexion and abduction of the glenohumeral joint. Pain decreased in both massage groups. This study showed increases in passive and active ranges of motion for flexion and abduction in patients who had massage based on the tensegrity principle. For pain outcomes, both classic and tensegrity massage groups demonstrated improvement. Copyright © 2013 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Traffic Sign Detection Based on Biologically Visual Mechanism

NASA Astrophysics Data System (ADS)

Hu, X.; Zhu, X.; Li, D.

2012-07-01

TSR (Traffic sign recognition) is an important problem in ITS (intelligent traffic system), which is being paid more and more attention for realizing drivers assisting system and unmanned vehicle etc. TSR consists of two steps: detection and recognition, and this paper describe a new traffic sign detection method. The design principle of the traffic sign is comply with the visual attention mechanism of human, so we propose a method using visual attention mechanism to detect traffic sign ,which is reasonable. In our method, the whole scene will firstly be analyzed by visual attention model to acquire the area where traffic signs might be placed. And then, these candidate areas will be analyzed according to the shape characteristics of the traffic sign to detect traffic signs. In traffic sign detection experiments, the result shows the proposed method is effectively and robust than other existing saliency detection method.

The maximum work principle regarded as a consequence of an optimization problem based on mechanical virtual power principle and application of constructal theory

NASA Astrophysics Data System (ADS)

Gavrus, Adinel

2017-10-01

This scientific paper proposes to prove that the maximum work principle used by theory of continuum media plasticity can be regarded as a consequence of an optimization problem based on constructal theory (prof. Adrian BEJAN). It is known that the thermodynamics define the conservation of energy and the irreversibility of natural systems evolution. From mechanical point of view the first one permits to define the momentum balance equation, respectively the virtual power principle while the second one explains the tendency of all currents to flow from high to low values. According to the constructal law all finite-size system searches to evolve in such configurations that flow more and more easily over time distributing the imperfections in order to maximize entropy and to minimize the losses or dissipations. During a material forming process the application of constructal theory principles leads to the conclusion that under external loads the material flow is that which all dissipated mechanical power (deformation and friction) become minimal. On a mechanical point of view it is then possible to formulate the real state of all mechanical variables (stress, strain, strain rate) as those that minimize the total dissipated power. So between all other virtual non-equilibrium states, the real state minimizes the total dissipated power. It can be then obtained a variational minimization problem and this paper proof in a mathematical sense that starting from this formulation can be finding in a more general form the maximum work principle together with an equivalent form for the friction term. An application in the case of a plane compression of a plastic material shows the feasibility of the proposed minimization problem formulation to find analytical solution for both cases: one without friction influence and a second which take into account Tresca friction law. To valid the proposed formulation, a comparison with a classical analytical analysis based on slices, upper/lower bound methods and numerical Finite Element simulation is also presented.

How Many Principles for Public Health Ethics?

PubMed Central

Coughlin, Steven S.

2009-01-01

General moral (ethical) principles play a prominent role in certain methods of moral reasoning and ethical decision-making in bioethics and public health. Examples include the principles of respect for autonomy, beneficence, nonmaleficence, and justice. Some accounts of ethics in public health have pointed to additional principles related to social and environmental concerns, such as the precautionary principle and principles of solidarity or social cohesion. This article provides an overview of principle-based methods of moral reasoning as they apply to public health ethics including a summary of advantages and disadvantages of methods of moral reasoning that rely upon general principles of moral reasoning. Drawing upon the literature on public health ethics, examples are provided of additional principles, obligations, and rules that may be useful for analyzing complex ethical issues in public health. A framework is outlined that takes into consideration the interplay of ethical principles and rules at individual, community, national, and global levels. Concepts such as the precautionary principle and solidarity are shown to be useful to public health ethics to the extent that they can be shown to provide worthwhile guidance and information above and beyond principles of beneficence, nonmaleficence, and justice, and the clusters of rules and maxims that are linked to these moral principles. Future directions likely to be productive include further work on areas of public health ethics such as public trust, community empowerment, the rights of individuals who are targeted (or not targeted) by public health interventions, individual and community resilience and wellbeing, and further clarification of principles, obligations, and rules in public health disciplines such as environmental science, prevention and control of chronic and infectious diseases, genomics, and global health. PMID:20072707

Spin-orbit driven phenomena in the isoelectronic L 10 -Fe(Pd,Pt) alloys from first principles

NASA Astrophysics Data System (ADS)

Kudrnovský, J.; Drchal, V.; Turek, I.

2017-12-01

The anomalous Hall effect (AHE) and the Gilbert damping (GD) are studied theoretically for the partially ordered L 10 -Fe(Pd,Pt) alloys. The varying alloy order and the spin-orbit coupling, which are due to the change in the Pd/Pt composition, allow for a chemical tuning of both phenomena which play an important role in the spintronic applications. The impact of the antisite disorder on the residual resistivity, AHE, and GD is studied from first principles using recently developed methods employing the Kubo-Bastin approach and the nonlocal torque operator method. The most interesting result is a different behavior of samples with low and high chemical orders. Good agreement between calculated and measured concentration trends is obtained for all quantities studied, while the absolute GD values are underestimated.

Comparison of Classical and Lazy Approach in SCG Compiler

NASA Astrophysics Data System (ADS)

Jirák, Ota; Kolář, Dušan

2011-09-01

The existing parsing methods of scattered context grammar usually expand nonterminals deeply in the pushdown. This expansion is implemented by using either a linked list, or some kind of an auxiliary pushdown. This paper describes the parsing algorithm of an LL(1) scattered context grammar. The given algorithm merges two principles together. The first approach is a table-driven parsing method commonly used for parsing of the context-free grammars. The second is a delayed execution used in functional programming. The main part of this paper is a proof of equivalence between the common principle (the whole rule is applied at once) and our approach (execution of the rules is delayed). Therefore, this approach works with the pushdown top only. In the most cases, the second approach is faster than the first one. Finally, the future work is discussed.

Effects of lattice parameters on piezoelectric constants in wurtzite materials: A theoretical study using first-principles and statistical-learning methods

NASA Astrophysics Data System (ADS)

Momida, Hiroyoshi; Oguchi, Tamio

2018-04-01

Longitudinal piezoelectric constant (e 33) values of wurtzite materials, which are listed in a structure database, are calculated and analyzed by using first-principles and statistical learning methods. It is theoretically shown that wurtzite materials with high e 33 generally have small lattice constant ratios (c/a) almost independent of constituent elements, and approximately expressed as e 33 ∝ c/a - (c/a)0 with ideal lattice constant ratio (c/a)0. This relation also holds for highly-piezoelectric ternary materials such as Sc x Al1- x N. We conducted a search for high-piezoelectric wurtzite materials by identifying materials with smaller c/a values. It is proposed that the piezoelectricity of ZnO can be significantly enhanced by substitutions of Zn with Ca.

Multiple point statistical simulation using uncertain (soft) conditional data

NASA Astrophysics Data System (ADS)

Hansen, Thomas Mejer; Vu, Le Thanh; Mosegaard, Klaus; Cordua, Knud Skou

2018-05-01

Geostatistical simulation methods have been used to quantify spatial variability of reservoir models since the 80s. In the last two decades, state of the art simulation methods have changed from being based on covariance-based 2-point statistics to multiple-point statistics (MPS), that allow simulation of more realistic Earth-structures. In addition, increasing amounts of geo-information (geophysical, geological, etc.) from multiple sources are being collected. This pose the problem of integration of these different sources of information, such that decisions related to reservoir models can be taken on an as informed base as possible. In principle, though difficult in practice, this can be achieved using computationally expensive Monte Carlo methods. Here we investigate the use of sequential simulation based MPS simulation methods conditional to uncertain (soft) data, as a computational efficient alternative. First, it is demonstrated that current implementations of sequential simulation based on MPS (e.g. SNESIM, ENESIM and Direct Sampling) do not account properly for uncertain conditional information, due to a combination of using only co-located information, and a random simulation path. Then, we suggest two approaches that better account for the available uncertain information. The first make use of a preferential simulation path, where more informed model parameters are visited preferentially to less informed ones. The second approach involves using non co-located uncertain information. For different types of available data, these approaches are demonstrated to produce simulation results similar to those obtained by the general Monte Carlo based approach. These methods allow MPS simulation to condition properly to uncertain (soft) data, and hence provides a computationally attractive approach for integration of information about a reservoir model.

Noether's Theorem and its Inverse of Birkhoffian System in Event Space Based on Herglotz Variational Problem

NASA Astrophysics Data System (ADS)

Tian, X.; Zhang, Y.

2018-03-01

Herglotz variational principle, in which the functional is defined by a differential equation, generalizes the classical ones defining the functional by an integral. The principle gives a variational principle description of nonconservative systems even when the Lagrangian is independent of time. This paper focuses on studying the Noether's theorem and its inverse of a Birkhoffian system in event space based on the Herglotz variational problem. Firstly, according to the Herglotz variational principle of a Birkhoffian system, the principle of a Birkhoffian system in event space is established. Secondly, its parametric equations and two basic formulae for the variation of Pfaff-Herglotz action of a Birkhoffian system in event space are obtained. Furthermore, the definition and criteria of Noether symmetry of the Birkhoffian system in event space based on the Herglotz variational problem are given. Then, according to the relationship between the Noether symmetry and conserved quantity, the Noether's theorem is derived. Under classical conditions, Noether's theorem of a Birkhoffian system in event space based on the Herglotz variational problem reduces to the classical ones. In addition, Noether's inverse theorem of the Birkhoffian system in event space based on the Herglotz variational problem is also obtained. In the end of the paper, an example is given to illustrate the application of the results.

Mapping Base Modifications in DNA by Transverse-Current Sequencing

NASA Astrophysics Data System (ADS)

Alvarez, Jose R.; Skachkov, Dmitry; Massey, Steven E.; Kalitsov, Alan; Velev, Julian P.

2018-02-01

Sequencing DNA modifications and lesions, such as methylation of cytosine and oxidation of guanine, is even more important and challenging than sequencing the genome itself. The traditional methods for detecting DNA modifications are either insensitive to these modifications or require additional processing steps to identify a particular type of modification. Transverse-current sequencing in nanopores can potentially identify the canonical bases and base modifications in the same run. In this work, we demonstrate that the most common DNA epigenetic modifications and lesions can be detected with any predefined accuracy based on their tunneling current signature. Our results are based on simulations of the nanopore tunneling current through DNA molecules, calculated using nonequilibrium electron-transport methodology within an effective multiorbital model derived from first-principles calculations, followed by a base-calling algorithm accounting for neighbor current-current correlations. This methodology can be integrated with existing experimental techniques to improve base-calling fidelity.

Analysis of Electric Vehicle DC High Current Conversion Technology

NASA Astrophysics Data System (ADS)

Yang, Jing; Bai, Jing-fen; Lin, Fan-tao; Lu, Da

2017-05-01

Based on the background of electric vehicles, it is elaborated the necessity about electric energy accurate metering of electric vehicle power batteries, and it is analyzed about the charging and discharging characteristics of power batteries. It is needed a DC large current converter to realize accurate calibration of power batteries electric energy metering. Several kinds of measuring methods are analyzed based on shunts and magnetic induction principle in detail. It is put forward power batteries charge and discharge calibration system principle, and it is simulated and analyzed ripple waves containing rate and harmonic waves containing rate of power batteries AC side and DC side. It is put forward suitable DC large current measurement methods of power batteries by comparing different measurement principles and it is looked forward the DC large current measurement techniques.