Complete Parameters Research Articles

Combined configuration-enthalpy model describing radiation-optical responses in chalcogenide semiconductor glasses

Combined configuration-enthalpy model evolving free energy configuration-coordinate and thermodynamic enthalpy diagrams is developed to describe the phenomenology of optical responses in structural metastability of chalcogenide semiconductor glasses of As-S system activated under prolonged physical ageing and high-energy γ-irradiation. The developed approach foresees glass stabilization in ground-state multibasin formed by rejuvenation-induced, irradiation-induced and/or most stable annealing-induced basins, interlinked by thermally-activated over-barrier jumping and through-barrier tunneling transitions. Effect of high-energy γ-irradiation in glasses is described due to vertical transitions of atomic sites into excited state followed by non-radiative relaxation into irradiation-induced glass ground state. This approach based on interlinked enthalpic and configuration-coordinate diagrams allows complete parameterization of optical responses related to induced metastable states, defined in blue (bleaching) or red (darkening) shifts in the transmission spectra of As-S glasses detected in the region of their fundamental optical absorption edge.

To the Development of Open Source Software for the Reconstruction of CAD Models

In this paper, we describe an open source software package aimed at solving reverse engineering problems for CAD models defined in polygonal form. We briefly discuss the main principles behind the new software, its architecture, and directions for its further development. The use of the software is illustrated by examples of a turbine blade. In the first example, the turbine blade is reconstructed automatically from a structured point cloud. Another example is the interactive reconstruction of the turbine blade from an unstructured surface triangulation. In both the cases, we use a surface skinning strategy enhanced by a curve fairing operator. We show that the modified skinning operator does not minimize the total bending energy of the surface, but yields a smooth patch where input inaccuracies are compensated for. The reconstruction result is a parametric model of the turbine blade where the design variables are the coordinates of the poles for each profile curve. The proposed software architecture can be used for partial or complete parameterization of reconstructed CAD models with the aim of their subsequent optimization.

The Feynman dispersion correction for MNDO extended to F, Cl, Br and I.

The recently introduced "Feynman" dispersion correction for MNDO (MNDO-F) has been extended to include the elements fluorine, chlorine, bromine and iodine and the original parameterization for hydrogen, carbon, nitrogen and oxygen improved by allowing individual damping radii for the elements. MNDO-F gives a root-mean-square deviation to reference interaction energies of 0.35kcalmol-1 for the complete parameterization dataset of H, C, N, O, F, Cl, Br and I containing compounds. Graphical Abstract The electrostatic potential at the 0.001a.u. isodensity surface of the π-complex between benzene and 1,3,5-triodobenzene calculated at the MNDO-F optimized geometry.

Circulation algorithm for partial eigenstructure assignment via state feedback

This paper treats the partial eigenstructure assignment problem for multi-variable linear systems by state feedback. Both the open-loop and the closed-loop eigenvalues are allowed to have arbitrary geometric and algebraic multiplicities. Based on a previously proposed result on partial eigenstructure assignment, a new complete parametric solution is derived, which gives a complete general parameterization of the feedback gain and also provides the general parametric expression for all the admissible eigenvector matrices. The solution involves, instead of a matrix inverse of full-dimension, the inverse of a matrix with a much smaller dimension. By using this new solution repeatedly, a circulation algorithm is proposed, which is simple and dramatically reduces the computational load in the case of large scale systems. Furthermore, two important special cases are especially examined, and simple and direct solutions are proposed, which no longer needs computation of matrix inverses, and suits best in the proposed circulation algorithm. The approach provides all the design degrees of freedom which can be further utilized to achieve additional closed-loop system performance. An illustrative example is thoroughly examined, which demonstrates the procedure and the advantages of the proposed parametric approach.

К разработке открытого программного обеспечения для реконструкции CAD-моделей

We describe an open source software package aimed at solving reverse engineering problems for CAD models defined in the polygonal form. We briefly discuss the main principles behind the new software, its architecture, and directions for further development. Examples of a turbine blade demonstrate the use of the software. In the first example, a turbine blade is reconstructed automatically from a structured point cloud. Another example is the interactive reconstruction of a turbine blade from an unstructured surface triangulation. In both cases, we use surface skinning strategy enhanced by a curve fairing operator. We illustrate by an example that the modified skinning operator does not minimize the total bending energy of the surface, but allows constructing a smooth patch where input inaccuracies are compensated. The reconstruction result is a parametric model of a turbine blade where the design variables are the coordinates of the poles of each profile curve. The presented software architecture can be used for partial or complete parameterization of the reconstructed CAD models aimed at their subsequent optimization.

Determination of ΛMS¯(nf=2) and analytic parametrization of the static quark-antiquark potential

While lattice QCD allows for reliable results at small momentum transfers (large quark separations), perturbative QCD is restricted to large momentum transfers (small quark separations). The latter is determined up to a reference momentum scale $\Lambda$, which is to be provided from outside, e.g. from experiment or lattice QCD simulations. In this article, we extract $\Lambda_{\overline{\textrm{MS}}}$ for QCD with $n_f=2$ dynamical quark flavors by matching the perturbative static quark-antiquark potential in momentum space to lattice results in the intermediate momentum regime, where both approaches are expected to be applicable. In a second step, we combine the lattice and the perturbative results to provide a complete analytic parameterization of the static quark-antiquark potential in position space up to the string breaking scale. As an exemplary phenomenological application of our all-distances potential we compute the bottomonium spectrum in the static limit.

An Improved Second‐Moment Closure Model for Langmuir Turbulence Conditions: Model Derivation and Validation

AbstractIn this study, an improved second‐moment closure model, the so‐called k‐ω model, which takes into consideration the Langmuir turbulent effect in the transport equations of turbulent kinetic energy and turbulent frequency, was developed. The Langmuir turbulent effect was also included in the vertical eddy viscosity and diffusivity coefficient. Langmuir turbulence production, as well as buoyancy production, anisotropic production, and vorticity production induced by velocity shear, was included in the pressure covariance parameterization to derive the stability function. The Langmuir effect and relatively complete pressure covariance parameterization inclusion can account for the influences of Langmuir turbulence and stratification in the vertical eddy viscosity and vertical eddy diffusion coefficients. Based on the modified model, one‐dimensional numerical experiments for horizontally homogeneous flows were carried out. The results indicate that the modified model is more accurate than other models in terms of the vertical eddy viscosity, vertical turbulence velocity variance, kinetic energy, and mean velocity profile compared with the large eddy simulation results. The simulated sea surface temperature (SST) and mixed layer depth of the modified model were compared with observations at Ocean Station Papa. When considering Langmuir turbulent effects, the modified model overcomes the shortcoming that the simulated SST is higher than the observed SST. Numerical results indicate that the k‐ω model performs better than the k‐kl model, although both models consider the Langmuir turbulent effect in the simulation of upper mixing motions.

Unipotent elements and generalized exponential maps

Let G be a simple and simply connected algebraic group over an algebraically closed field k of characteristic p>0. Assume that p is good for the root system of G and that the covering map Gsc→G is separable. In previous work we proved the existence of a (not necessarily unique) Springer isomorphism for G that behaved like the exponential map on the restricted nullcone of G.In the present paper we give a formal definition of these maps, which we call ‘generalized exponential maps.’ We provide an explicit and uniform construction of such maps for all root systems, demonstrate their existence over Z(p), and give a complete parameterization of all such maps. One application is that this gives a uniform approach to dealing with the “saturation problem” for a unipotent element u in G, providing a new proof of the known result that u lies inside a subgroup of CG(u) that is isomorphic to a truncated Witt group. We also develop a number of other explicit and new computations for g and for G. This paper grew out of an attempt to answer a series of questions posed to us by P. Deligne, who also contributed several of the new ideas that appear here.

Full Cell Parameterization of a High-Power Lithium-Ion Battery for a Physico-Chemical Model: Part I. Physical and Electrochemical Parameters

Physico-chemical models are key for a successful use of lithium-ion batteries, especially under extreme conditions. For correctly simulating of the internal battery states and battery aging a suitable set of material properties is needed. This work presents methods to extract these parameters from commercial cells and demonstrates them analyzing a high-power prismatic cell. In a first step, the electrolyte analysis is described, followed by an examination of the active material. The composition as well as the porous structure are measured using optical emission spectroscopy and Hg-porosimetry. To determine the electrochemical properties of the electrode materials, coin cells with lithium as counter electrode are build. With these test cells, open circuit voltage curves and galvanostatic intermittent titration technique measurements are performed to determine the electrode balancing as well as the diffusion constants of the active material. Electrochemical impedance spectroscopy experiments on the full cell are used to determine the charge transfer. In the second part of this paper, a determination of the thermal parameters as well as a validation for the complete parameterization are described.

A coupled model of interior balanced and boundary flow

Ocean circulation modeling requires parameterizations of sub-grid scale processes, which in turn involves two separate issues. First, the parameterization should mirror the effect of important sub-grid dynamics and second, constants and boundary conditions as required by the parameterization must be determined. In modern ocean circulation modeling, many parameterizations take the form of viscous operators with poorly known coefficients, and the boundary conditions options are free-slip, partial-slip or no-slip, suitably adjusted for the order of the operator. The extent to which viscous operators are dynamically apt is unclear and there is virtually no dynamical guidance on how to choose between the boundary conditions. Often the decision about the suitability of the parameterizations and the boundary conditions is made based on qualitative characteristics of the solution, which is somewhat subjective. Here, a dynamical boundary layer model is developed that explicitly determines the boundary potential vorticity fluxes resulting from the sub-grid scale interactions of the resolved flow with the boundaries. When applied to a quasi-geostrophic model, comparisons of model evolution with high resolution primitive equation simulations are favorable. The recipe outlined here, while far from a complete parameterization of boundary dynamics, represents a step toward resolving the issues currently surrounding sub-grid scale parameterization. The results also argue that boundary dynamics naturally dissipate balanced energy and are likely to represent a principal means by which the oceanic mesoscale energy budget is balanced.

The aerodynamic optimization design of turbine cascade nonaxisymmetric endwall and the midgap influence assessment

The nonaxisymmetric endwall profiling has been proven to be an effective tool to reduce the secondary flow loss in turbomachinery. In the present work, first, without considering the endwall midgap in the real machine, an endwall optimization design procedure for reducing secondary flow losses has been developed, which allowed complete three-dimensional parameterization turbine endwall design. The profile of the endwall has been designed using automatic numerical optimization by means of an improved efficient global optimization algorithm based on kriging surrogate model. Next, a large-scale linear cascade with a low-speed wind tunnel has been chosen for the experimental validation of the optimization results. The experimental measurements and numerical simulations both demonstrated that the total pressure loss and secondary flow intensity were reduced with the nonaxisymmetric endwall used in the cascade passage. Then, in order to evaluate the ability of the optimized nonaxisymmetric endwall with the midgap, the midgap was added in for both the baseline flat endwall and the optimized nonaxisymmetric endwall in the numerical simulations analysis. The entropy generation rates analysis were used for the investigation of loss distribution in the passage. For the cascade in the present work, with the midgap added in, the optimized nonaxisymmetric endwall did not perform as well as the situation without the midgap in the loss reduction. In addition, comparing to the baseline flat endwall, the optimized nonaxisymmetric endwall needed more net leakage flow to avoid the ingress of passage flow into the midgap.

Beam-target double-spin asymmetry in quasielastic electron scattering off the deuteron with CLAS

Quasi-elastic electron scattering on the deuteron is a benchmark reaction to test our understanding of deuteron structure and the properties and interactions of the two nucleons bound in the deuteron. The experimental data presented here can be used to test state-of-the-art models of the deuteron and the two-nucleon interaction in the final state after two-body breakup of the deuteron. Focusing on polarization degrees of freedom, we gain information on spin-momentum correlations in the deuteron ground state (due to the D-state admixture) and on the limits of the Impulse Approximation (IA) picture as it applies to measurements of spin-dependent observables like spin structure functions for bound nucleons. We measured the beam-target double spin asymmetry for quasi-elastic electron scattering off the deuteron at several beam energies using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The deuterons were polarized along (or opposite to) the beam direction. The double spin asymmetries were measured as a function of photon virtuality , missing momentum, and the angle between the (inferred) "spectator" neutron and the momentum transfer direction. The results are compared with a recent model that includes Final State Interactions (FSI) using a complete parameterization of nucleon-nucleon scattering, as well as a simplified model using the Plane Wave Impulse Approximation (PWIA). We find overall good agreement with both the PWIA and FSI expectations at low to medium missing momenta, including the change of the asymmetry due to the contribution of the deuteron D-state at higher momenta. At the highest missing momenta, our data clearly agree better with the calculations including FSI.

Permutation invariant properties of primitive cubic quadruples

Based on a specific quadratic Hopf map between the Euclidean spaces of dimension four and three that is associated with Euler’s complete rational parameterization of the four cubes equation, we study the permutation invariant properties of the primitive integer cubic quadruples that solve this equation. Fixing the coordinate with maximum height and taking it positive, our main result describes the six positive primitive triples that leave it invariant under the inverted cubic map to this Hopf map and permute the remaining integer coordinates. The obtained invariant primitive triples are ordered in the so-called integer triple ordering, so that the minimum triple with respect to this ordering determines each primitive cubic quadruple uniquely. Implications for the counting and enumeration of all primitive cubic quadruples are mentioned. A list of all primitive cubic quadruples with positive maximum height below 100 and their minimum invariant triples is given. The relationship with the famous Taxicab and Cabtaxi numbers is also explained.

Application of a Computational Glass Model to the Shock Response of Soda-Lime Glass

This article details the implementation and application of the glass-specific computational constitutive model by Holmquist and Johnson (J Appl Mech 78:051003, 2011) to simulate the dynamic response of soda-lime glass under high rate and high pressure shock conditions. The predictive capabilities of this model are assessed through comparison of experimental data with numerical results from computations using the CTH shock physics code. The formulation of this glass model is reviewed in the context of its implementation within CTH. Using a variety of experimental data compiled from the open literature, a complete parameterization of the model describing the observed behavior of soda-lime glass is developed. Simulation results using the calibrated soda-lime glass model are compared to flyer plate and Taylor rod impact experimental data covering a range of impact and failure conditions spanning an order of magnitude in velocity and pressure. The complex behavior observed in the experimental testing is captured well in the computations, demonstrating the capability of the glass model within CTH.

Backtransformation: a new representation of data processing chains with a scalar decision function

Data processing often transforms a complex signal using a set of different preprocessing algorithms to a single value as the outcome of a final decision function. Still, it is challenging to understand and visualize the interplay between the algorithms performing this transformation. Especially when dimensionality reduction is used, the original data structure (e.g., spatio-temporal information) is hidden from subsequent algorithms. To tackle this problem, we introduce the backtransformation concept suggesting to look at the combination of algorithms as one transformation which maps the original input signal to a single value. Therefore, it takes the derivative of the final decision function and transforms it back through the previous processing steps via backward iteration and the chain rule. The resulting derivative of the composed decision function in the sample of interest represents the complete decision process. Using it for visualizations might improve the understanding of the process. Often, it is possible to construct a feasible processing chain with affine mappings which simplifies the calculation for the backtransformation and the interpretation of the result a lot. In this case, the affine backtransformation provides the complete parameterization of the processing chain. This article introduces the theory, provides implementation guidelines, and presents three application examples.

Watershed Management Structures and Decision Making Frameworks

Integrated watershed management has been adopted worldwide as best management practices, can minimise the climate change impact on agricultural production and fresh water resources. Critical elements for making best watershed management systems, like precise locations and designs of recharge structures, correct location of check dams within the watershed to ensure the optimum utilization have been discussed. Best Management Practices (BMP) for agricultural watershed management that includes integrated and consortium approach has been proposed. Case study demonstrates that the construction of artificial recharge structures like check dams on the upstream of the tributaries not only causes additional recharge but is also useful in improving the ground water quality. Study also proposes a watershed performance assessment model for identifying the parameters in the watershed, whose precise characterization is essential for the success of any watershed management program. A methodology has been develop for the evaluation of a complete watersheds model parameterization and performance scores has been assigned on the basis of parameter impact on output. The analysis and methodology of the proposed work can extremely useful for the practice of evaluation and effective implementation of watersheds.

A self-consistent optimization of multicomponent solution properties: Ab initio molecular dynamic simulations and the MgO–SiO2 miscibility gap under pressure

We propose a new approach to parameterizing the Gibbs energy of a multicomponent solution as a function of temperature, pressure and composition. It uses the quasichemical model in the second nearest neighbor approximation and considers both a polynomial representation (for low pressure) and an exponential decay representation (for moderate-to-high pressure) of the excess molar volume νxs to extend thermodynamic behavior to elevated pressure. This approach differs from previous configuration-independent regular or associated solution-type models of multicomponent silicate liquids at elevated pressure and can account for any structural or short-range order data that may be available. A simultaneous least squares fit of the molar volume and the molar enthalpy of mixing data obtained from First Principles Molecular Dynamics (FPMD) simulations at various pressures enables complete parameterization of the excess thermodynamic properties of the solution. Together with consistently optimized properties of coexisting solids, this enables prediction of pressure–temperature–composition phase diagrams associated with melting. Although the method is extensible to natural multicomponent systems, we apply the procedure as a first test case to the important planetary model system MgO–SiO2 using FPMD data found in the literature. One key result of this optimization, which depends only on the derived excess properties of the liquid phase, is that the consolute temperature of the SiO2-rich miscibility gap is predicted to decrease with increasing pressure. This appears to be in disagreement with available experimental constraints and suggests possible thermodynamic inconsistency between FPMD data and experimental phase equilibrium data in the 0–5GPa pressure range. We propose a new thermodynamic consistency criterion relating the signs of νxs and other excess properties and discuss the need for precise calculations of derivatives of excess properties. Finally, the potential reappearance of the miscibility gap in the MgO–SiO2 system above 5GPa is discussed in light of this work.

Algal productivity modeling: a step toward accurate assessments of full-scale algal cultivation.

A new biomass productivity model was parameterized for Chlorella vulgaris using short-term (<30 min) oxygen productivities from algal microcosms exposed to 6 light intensities (20-420 W/m(2)) and 6 temperatures (5-42 °C). The model was then validated against experimental biomass productivities recorded in bench-scale photobioreactors operated under 4 light intensities (30.6-74.3 W/m(2)) and 4 temperatures (10-30 °C), yielding an accuracy of ± 15% over 163 days of cultivation. This modeling approach addresses major challenges associated with the accurate prediction of algal productivity at full-scale. Firstly, while most prior modeling approaches have only considered the impact of light intensity on algal productivity, the model herein validated also accounts for the critical impact of temperature. Secondly, this study validates a theoretical approach to convert short-term oxygen productivities into long-term biomass productivities. Thirdly, the experimental methodology used has the practical advantage of only requiring one day of experimental work for complete model parameterization. The validation of this new modeling approach is therefore an important step for refining feasibility assessments of algae biotechnologies.

On the quasi-balanceable class of linear quantum stochastic systems

This paper is concerned with the characterization of the quasi-balanceable class of linear quantum stochastic systems (i.e., systems that can be approximated via the recently proposed quasi-balanced truncation method). It has previously been shown that the quasi-balanceable class of systems includes the class of completely passive systems. In this work, we refine the previously established characterization of quasi-balanceable systems and show that the class of quasi-balanceable systems is strictly larger than the class of completely passive systems. We derive a novel characterization of completely passive linear quantum stochastic systems solely in terms of the controllability Gramian of such systems. Exploiting this result, we prove that all linear quantum stochastic systems with a pure Gaussian steady state (active systems included) are all quasi-balanceable, and establish a new complete parameterization for this important class of systems. Examples are provided to illustrate our results.

Complete parameterization of temporally and spectrally resolved laser induced fluorescence data with applications in bio-photonics

We present a set of spectrally and temporally resolved clinical fluorescence data—with two separate excitation wavelengths—that was recorded in vivo. We demonstrate that data in the spectral and temporal domains are in certain ways coupled and provide a method for integrated and effective parameterization of spectrally and temporally resolved fluorescence (i.e., time-resolved emission spectra). This parameterization is based on linear algebra, matrix formulation and system identification. We demonstrate how to empirically extract single exponentially decaying components and provide rectified emission spectra without prior knowledge. We investigate the potential for improved cancer diagnostics according to the reduced parameters along the various domains. In this case, in terms of cancer diagnostics, we were unable to identify any benefits of simultaneously measuring both the temporal and spectral properties of the observed fluorescence. However, we note that this may be explained by an important experimental bias present in many studies of optical cancer diagnostics, namely, that, in general, suspected lesions always differ visually from the neighboring healthy tissue.