Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “linearization”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

The Problem of Package Guidance with Incomplete Information for a Linear Control System with a Delay

The control-package method is applied to solve the problem of constructing guaranteed positional guidance for a linear control dynamical system with a delay under incomplete information about the initial state. The problem is solved for the case when the initial state is contained in a compact functional set. A solvability criterion and a method for the construction of a guidance program package are proposed. The proposed procedure is applied to a particular linear control system of delayed differential equations.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Higher curvature gravities, unlike GR, cannot be bootstrapped from their (usual) linearizations

In this work, we show that higher curvature order gravities, in particular the propagating quadratic curvature models, cannot be derived by self-coupling from their linear, flat space, forms, except through an unphysical version of linearization, only GR can. Separately, we comment on an early version of the self-coupling bootstrap.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Sensitivity Gains, Linearity, and Spectral Reproducibility in Nonuniformly Sampled Multidimensional MAS NMR Spectra of High Dynamic Range.

Recently, we have demonstrated that considerable inherent sensitivity gains are attained in MAS NMR spectra acquired by nonuniform sampling (NUS) and introduced maximum entropy interpolation (MINT) processing that assures the linearity of transformation between the time and frequency domains. In this report, we examine the utility of the NUS/MINT approach in multidimensional datasets possessing high dynamic range, such as homonuclear 13C–13C correlation spectra. We demonstrate on model compounds and on 1–73-(U-13C,15N)/74–108-(U-15N) E. coli thioredoxin reassembly, that with appropriately constructed 50 % NUS schedules inherent sensitivity gains of 1.7–2.1-fold are readily reached in such datasets. We show that both linearity and line width are retained under these experimental conditions throughout the entire dynamic range of the signals. Furthermore, we demonstrate that the reproducibility of the peak intensities is excellent in the NUS/MINT approach when experiments are repeated multiple times and identical experimental and processing conditions are employed. Finally, we discuss the principles for design and implementation of random exponentially biased NUS sampling schedules for homonuclear 13C–13C MAS correlation experiments that yield high quality artifact-free datasets.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2020

Development of Transition-Edge Sensor X-ray Microcalorimeter Linear Array for Compton Scattering and Energy Dispersive Diffraction Imaging

In this paper we present a strip transition-edge sensor microcalorimeter linear array detector developed for energy dispersive X-ray diffraction imaging and Compton scattering applications. The prototype detector is an array of 20 transition-edge sensors with absorbers in strip geometry arranged in a linear array. We discuss the fabrication steps needed to develop this array including Mo/Cu bilayer, Au electroplating, and proofof-principle fabrication of long strips of SiNx membranes. We demonstrate minimal unwanted effect of strip geometry on X-ray pulse response and showlinear relationship of 1/pulse height and pulse decay times with absorber length. For the absorber lengths studied, our preliminary measurements show energy resolutions of 40-180eV near 17 keV. Furthermore, we show that the heat flow to the cold bath is nearly independent of the absorber area and depends on the SiNx membrane geometry.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Efficient Trainability of Linear Optical Modules in Quantum Optical Neural Networks

The existence of “barren plateau landscapes” for generic discrete-variable quantum neural networks, which obstructs efficient gradient-based optimization of cost functions defined by global measurements, would be surprising in the case of generic linear optical modules in quantum optical neural networks due to the tunability of the intensity of continuous variable states and the relevant unitary group having exponentially smaller dimension. We demonstrate that coherent light in m modes can be generically compiled efficiently if the total intensity scales sublinearly with m, and extend this result to cost functions based on homodyne, heterodyne, or photon detection measurement statistics, and to noisy cost functions in the presence of attenuation. Here, we further demonstrate efficient trainability of m mode linear optical quantum circuits for variational mean field energy estimation of positive quadratic Hamiltonians for input states that do not have energy exponentially vanishing with m.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Theory of d-Wave High Temperature Superconductivity in the Cuprates Involving Non-linear Lattice Modes

The transition mechanism in high temperature cuprate superconductors is an outstanding puzzle. A previous suggestion on the role of non-linear local lattice instability modes on the microscopic pairing mechanism in high temperature cuprate superconductors (Lee, J. Supercond. Nov. Magn. 23(3), 333; 2009) is re-examined to provide a viable mechanism for superconductivity in these cuprates via an unusual lattice vibration in which an electron is predominantly interacting with a non-linear Q{sub 2} mode of the oxygen clusters in the CuO{sub 2} planes. It is shown that the interaction has explicit d-wave symmetry and leads to an indirect coupling of d-wave symmetry between electrons. As a follow-up of Lee (J. Supercond. Nov. Magn. 23(3), 333; 2009), in this paper, we report detailed derivation of the superconducting gap equation and numerical solutions for the transition temperature as inherently integrated into the so-called extended Hubbard model (EHM). A unique feature in the EHM is that the transition temperature has an inherent k-dependence. In addition, superconducting gap solutions are restrained to specific regions in the first Brillouin zone (1BZ). It is very feasible to expect that the EHM naturally inherits a huge parameter space in which experimentally measured results, such as the well-known superconducting dome and the phase diagram from electronic Raman scattering (Sacuto et al., Rep. Prog. Phys. 76(2), 022502; 2013) can be accommodated. The EHM model hence offers a viable venue to search for or confirm any signature in k-point-sensitive experimental measurements.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Explanation of Non-linear In-Plane Resistivity and Hall Coefficient in the Normal State of Cuprates: Polaronic Approach

We present a theoretical study of the in-plane resistivity ρ{sub ab}(T) and Hall coefficient R{sub H}(T) within the polaronic model and precursor pairing scenario by considering a two-component charge carrier picture in the normal state of high-temperature superconducting cuprates (HTSC). Here, we use a Boltzmann-equation approach and extended BCS-like model to compute ρ{sub ab}(T) and R{sub H}(T) in the τ-approximation. The opening of the pseudogap (PG) in the normal state of the cuprates should affect their transport properties. We have found that the transition to the PG regime and the effective conductivity of charge carriers in the normal state are responsible for the pronounced non-linear temperature dependence of ρ{sub ab} and R{sub H}. With the two-component model analysis, we conclude that the opening of the BCS-like PG, while the non-linear temperature dependence of ρ{sub ab} and R{sub H} could be understood as a consequence of pairing fluctuations in the PG state of cuprate superconductors. The calculated results for ρ{sub ab}(T) and R{sub H}(T) were compared with the experimental data obtained for various hole-doped cuprates. For all the considered cases, a good quantitative agreement was found between theory and experimental data. We also show that the energy scales of the binding energies of charge carriers are identified by PG crossover temperature on the cuprate phase diagram.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Global Existence and Decay Rates of the Solutions Near Maxwellian for Non-linear Fokker–Planck Equations

In this paper, we study the global existence and decay rates of the solutions near Maxwellian for non-linear Fokker–Planck equations in the whole space. The global existence is proved by combining uniform-in-time energy estimates with local solution constructed by Picard type iteration sequence. The decay rates of the nonlinear model is obtained by using the precise spectral analysis of the linearized Fokker–Planck operator as well as the energy method. The nonlinearity in the model brings new difficulty to the energy estimates, which is resolved by additional tailored weighted-in-v energy estimates suitable for Fokker–Planck operators.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

The Cauchy Problem for Boltzmann Bi-linear Systems: The Mixing of Monatomic and Polyatomic Gases

Abstract From a unified vision of vector valued solutions in weighted Banach spaces, this paper establishes the existence and uniqueness for space homogeneous Boltzmann bi-linear systems with conservative collisional forms arising in complex gas dynamical structures. This broader vision is directly applied to dilute multi-component gas mixtures composed of both monatomic and polyatomic gases. Such models can be viewed as extensions of scalar Boltzmann binary elastic flows, as much as monatomic gas mixtures with disparate masses and single polyatomic gases, providing a unified approach for vector valued solutions in weighted Banach spaces. Novel aspects of this work include developing the extension of a general ODE theory in vector valued weighted Banach spaces, precise lower bounds for the collision frequency in terms of the weighted Banach norm, energy identities, angular or compact manifold averaging lemmas which provide coerciveness resulting into global in time stability, a new combinatorics estimate for p -binomial forms producing sharper estimates for the k -moments of bi-linear collisional forms. These techniques enable the Cauchy problem improvement that resolves the model with initial data corresponding to strictly positive and bounded initial vector valued mass and total energy, in addition to only a $$2^+$$ 2 + moment determined by the hard potential rates discrepancy, a result comparable in generality to the classical Cauchy theory of the scalar homogeneous Boltzmann equation.

Physics↗
DOE OSTI2018

Discretization Procedure for Linear Dynamical Systems

We describe in detail a method of construction of a discrete linear dynamical model of a controllable object in the recurrent Cauchy form corresponding to an initial continuous dynamical system. We describe discretization algorithms for free and forced motion of a linear continuous dynamical system and propose methods of construction of the state, control, and perturbation transition matrices.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On a Method of Study of Specific Asymptotic Stability of Solutions to a Sixth-Order Linear Integrodifferential Volterra Equation

We state sufficient conditions of the asymptotic stability on the semi-axis of solutions to a linear, homogeneous, sixth-order integrodifferential Volterra-type equation in the case where solutions of the corresponding linear, homogeneous, sixth-order differential equation are asymptotically unstable. We also present a new method and an illustrating example.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On Lower Estimates of Solutions and Their Derivatives to a Fourth-Order Linear Integrodifferential Volterra Equation

We examine solutions of the problem on sufficient conditions that guarantee a lower estimate and tending to infinity of solutions and their derivatives up to the third order to a fourth-order linear integrodifferential Volterra equation. For this purpose, we develop a method based on the nonstandard reduction method (S. Iskandarov), the Volterra transformation method, the method of shearing functions (S. Iskandarov), the method of integral inequalities (Yu. A. Ved’ and Z. Pakhyrov), the method of a priori estimates (N. V. Azbelev, V. P. Maksimov, L. F. Rakhmatullina, and P. M. Simonov, 1991, 2001), the Lagrange method for integral representations of solutions to first-order linear inhomogeneous differential equations, and the method of lower estimate of solutions (Yu. A. Ved’ and L. N. Kitaeva).

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Asymptotics of the General Solution of a Linear Singularly Perturbed System of Higher-Order Differential Equations with Degenerations

By using the theory of polynomial matrix pencils, we construct the asymptotics of linearly independent solutions of homogeneous singularly perturbed system of linear differential equations of any order m with matrices at higher derivatives degenerating as a small parameter approaches zero. The general case is analyzed. In this case, the limit matrix pencil has several finite and infinite elementary divisors of both the same and different multiplicities. The corresponding asymptotic estimates are presented.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Small scale electron linear accelerators for industrial applications

Linear accelerators (linacs), producing electron or X-ray radiation in the MeV range, are critical tools for industrial irradiation, medical device sterilization, food pasteurization, non-destructive testing, security, medical, and many other applications. Many of these applications require compact and flexible radiation sources. In this paper, we present new technologies for small-scale electron linear accelerators and examples of their practical implementations. Furthermore, these developments include low energy accelerators with self-shielding options and form factors, ranging from cabinet-size to hand-portable generators; medium-energy accelerators for novel radiotherapy and security applications; and high-energy 10 MeV linacs capable of reaching 20–35 kW beam power for emerging industrial and phytosanitary applications

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Dynamic power and chirp measurements of amplified 19 ps pulses in traveling-wave and reflective semiconductor optical amplifiers using a linear pulse characterization technique

The dynamic chirp and power of amplified pulses in semiconductor optical amplifiers is of importance in the application of these devices as conventional amplifiers and in optical signal processing. Non-linear measurement techniques are appropriate for pulsewidths less than 5 ps but have low sensitivity for wider pulsewidths commonly present in moderate bit rate optical systems. Typical measurements of chirp and power of 20 GHz repetition rate amplified 19 ps pulsewidth pulses in traveling-wave and reflective SOAs are obtained using a linear characterization technique based on small-signal sinusoidal modulation at half the pulse stream repetition rate and post-processing of the resulting optical spectrums. The results show that the amplified pulse dynamic power and chirp can have a complex structure and thereby pulse spectrum, which in turn can influence pulse propagation in optical fiber.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 10{sup 7} detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗