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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.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A new computational framework for spinor-based relativistic exact two-component calculations using contracted basis functions

Here, a new computational framework for spinor-based relativistic exact two-component (X2C) calculations is developed using contracted basis sets with a spin–orbit contraction scheme. Generally contracted, j-adapted basis sets of p-block elements using primitive functions in the correlation-consistent basis sets are constructed for the X2C Hamiltonian with atomic mean-field spin–orbit integrals (the X2CAMF scheme). The contraction coefficients are taken from atomic X2CAMF Hartree–Fock spinors, thereby following the simple concept of a linear combination of atomic orbitals. Benchmark calculations of spin–orbit splittings, equilibrium bond lengths, and harmonic vibrational frequencies demonstrate the accuracy and efficacy of the j-adapted spin–orbit contraction scheme.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Case Studies in Leveraging Performance Contracts for Resilience Projects

The resilience of federal facilities has become increasingly important among lawmakers, agency leadership, and the American public as high impact natural hazards occur more frequently over time. Resilience is broadly defined as the ability of a federal facility to withstand, respond to, and recover rapidly from disruptions to maintain critical functions. The Department of Energy (DOE) Federal Energy Management Program (FEMP) was codified to facilitate the strengthening of federal energy and water efficiency and resilience. Performance contracting is one of the mechanisms through which federal agencies can finance projects at their facilities, but resilience improvement measures do not always result in utility cost savings, which are the primary driver behind performance contracts. This report provides example cases where performance contracts, specifically energy savings performance contracts (ESPC) or utility energy service contracts (UESCs), were used to implement a resilience measure at a federal facility.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1972

Application of Contraction Mappings to the Control of Nonlinear Systems

The theoretical and applied aspects of successive approximation techniques are considered for the determination of controls for nonlinear dynamical systems. Particular emphasis is placed upon the methods of contraction mappings and modified contraction mappings. It is shown that application of the Pontryagin principle to the optimal nonlinear regulator problem results in necessary conditions for optimality in the form of a two point boundary value problem (TPBVP). The TPBVP is represented by an operator equation and functional analytic results on the iterative solution of operator equations are applied. The general convergence theorems are translated and applied to those operators arising from the optimal regulation of nonlinear systems. It is shown that simply structured matrices and similarity transformations may be used to facilitate the calculation of the matrix Green functions and the evaluation of the convergence criteria. A controllability theory based on the integral representation of TPBVP's, the implicit function theorem, and contraction mappings is developed for nonlinear dynamical systems. Contraction mappings are theoretically and practically applied to a nonlinear control problem with bounded input control and the Lipschitz norm is used to prove convergence for the nondifferentiable operator. A dynamic model representing community drug usage is developed and the contraction mappings method is used to study the optimal regulation of the nonlinear system.

Killingsworth, W. R., Jr.↗
NASA NTRS1984

On the design of contractions and settling chambers for optimal turbulence manipulations in wind tunnels

The sensitivity of a moderate axisymmetric contraction of turbulence to upstream conditions is parametrically investigated in terms of turbulence intensities and integral length scales. Semi-empirical correlations are derived to characterize the development of turbulence intensities and integral length scales downstream of typical wind-tunnel turbulence manipulators. A new approach is described, permitting wind-tunnel designers to select the characteristic mesh of the turbulence manipulators, a well as the distance from them to the contraction, in order to obtain certain required turbulence characteristics in the test section at the exit of the contraction. The design charts strongly suggest that it may not be possible to achieve small scales and low intensities simultaneously, when using a contraction ratio of nine or larger. The results also confirm that the rapid distortion theory is only valid, with a proper viscous dissipation correction, up to the 'critical point' of a contraction. At that point, the scales of the various components of the velocity are equal and intercomponent transfer from the lateral to the streamwise velocities commences.

Nagib, H. M.↗
NASA NTRS1944

The Theory of Propellers III : the Slipstream Contraction with Numerical Values for Two-Blade and Four-Blade Propellers

As the conditions of the ultimate wake are concerned both theoretically and practically, the magnitude of the slipstream contraction has been calculated. It will be noted that the contraction in a representative case is of the order of only 1 percent of the propeller diameter. In consequence, all calculations need involve only first-order effects. Curves and tables are given for the contraction coefficient of two-blade and four-blade propellers for various values of the advance ratio; the contraction coefficient is defined as the contraction in the diameter of the wake helix in terms of the wake diameter at infinity. The contour lines of the wake helix are also shown at four values of the advance ratio in comparison with the contour lines for an infinite number of blades.

Theodorsen, Theodore↗
NASA NTRS1994

The advantages of cost plus award fee contracts

A Cost Plus Award Fee contract is the best procurement vehicle for the high-tech, one-of-a-kind, development projects that constitute most of NASA'S projects. The use of this type of contract requires more government and contractor effort than any other forms of contracts. An award fee contract is described as an arrangement whereby the government periodically awards a fee consistent with the cost, schedule and technical performance that is achieved by a contractor during a preset period with preset award fee pools. It's the only contracting method where both the government and contractor goals are closely linked. It also has a built-in mechanism to conveniently alter and emphasize program events in order to current external and internal situations. The award fee process also demands good communication between government and contractor participants.

Keathley, William C.↗
NASA NTRS1995

Advanced Transportation System Studies Technical Area 2 (TA-2) Heavy Lift Launch Vehicle Development Contract: Technical Results - Volume 2

The purpose of the Advanced Transportation System Studies (ATSS) Technical Area 2 (TA-2) Heavy Lift Launch Vehicle Development contract was to provide advanced launch vehicle concept definition and analysis to assist NASA in the identification of future launch vehicle requirements. Contracted analysis activities included vehicle sizing and performance analysis, subsystem concept definition, propulsion subsystem definition (foreign and domestic), ground operations and facilities analysis, and life cycle cost estimation. This document is Volume 2 of the final report for the contract. It provides documentation of selected technical results from various TA-2 analysis activities, including a detailed narrative description of the SSTO concept assessment results, a user's guide for the associated SSTO sizing tools, an SSTO turnaround assessment report, an executive summary of the ground operations assessments performed during the first year of the contract, a configuration-independent vehicle health management system requirements report, a copy of all major TA-2 contract presentations, a copy of the FLO launch vehicle final report, and references to Pratt & Whitney's TA-2 sponsored final reports regarding the identification of Russian main propulsion technologies.

Source record↗
NASA NTRS2002

Neural Correlates of Birth: Labor Contractions Induce C-Fos Expression In Newborn Rat Brain

At birth, the newborn mammal must make rapid adaptations to the extrauterine environment to survive. We have previously shown that labor contractions augment the appearance of adaptive responses at birth, viz., postpartum breathing and the onset of suckling. Since neuronal activity has been shown to upregulate the activity of immediate early genes (IEGs) in the brain, we analyzed the neural distribution of c-Fos protein expression in newborn rats using immunohistochemistry. Previous studies have reported a burst of c-Fos mRNA expression in mouse and rat brain at birth however relationships to labor and delivery have not been examined. In the present study, we exposed near-term rat fetuses to elements of the vaginal birth process: 1) Simulated labor contractions. 2) Postpartum cooling (22 deg C). 3) Umbilical cord occlusion. and 4) Stroking to mimic postpartum licking by the dam. Cardinally delivered newborns (VG) were compared with those delivered by cesarean section following either prenatal exposure to compressions (C) [simulated labor contractions], or no compressions (NC) [no labor contractions]. Similar patterns of c-fos activation were observed throughout hypothalamic and thalamic nuclei, hippocampus and cerebral cortex in VG and C newborns that were not apparent in NC newborns. Our results indicate that labor contractions play a role in the induction of widespread neural activation in the newborn brain.

Ronca, A. E.↗
DOE OSTI2024

Best Practices for Smart Grid-Interactive Efficient Building Ready Performance Contracts

Grid-interactive efficient building (GEB) measures reduce costs and optimize energy use for additional grid services by coordinating building energy loads and providing continuous demand management. Incorporating GEB energy conservation measures (ECMs) in performance contracts is reliant upon multiple factors. These factors include site selection with utility tariffs and incentives favorable to GEB, the identification of GEB as a priority in the initial stages of the contracting process, integration of GEB within comprehensive performance contracts with multiple other ECMs, and careful consideration of GEB measurement and verification (M&V) for energy savings performance contracts (ESPCs) and performance assurance for utility energy service contracts (UESCs).

building energy loads↗
DOE OSTI2025

Construction of 3D MHD pressure drop correlation and flow characterization in the contraction region of a fusion blanket manifold

Inlet and outlet manifolds are typical components of liquid metal (LM) blanket designs of a fusion power reactor to be used to distribute the LM flow into breeding channels and collect it at the exit of the blanket. High pressure loss in the magnetohydrodynamic (MHD) flows featuring abrupt geometrical changes is one of the main feasibility issues of such designs. Recently, optimization studies were conducted to construct 3D MHD pressure drop correlations for a LM flow in an electrically insulating manifold with gradual expansion. Here, the 3D computational approach developed in that study is applied to the outlet manifold featuring gradual contraction. A systematic analysis was performed with a total number of 135 flow cases computed with COMSOL Multiphysics for Hartmann numbers 1000 < Ha < 10,000, Reynolds numbers 100 < Re < 12,000, and contraction angles 45° < θ < 75° for a fixed contraction ratio of 4. The effects of Ha, Re and θ on the flow recirculation, development length and the total pressure drop were carefully examined. A linear regression analysis was used to determine the power rule of pressure drop coefficient k related to Ha and Re, demonstrating a good match with the Ludford layer theory. Eventually, a correlation for the 3D MHD pressure drop coefficient was constructed as a function of Ha, Re and θ. Further, the results were compared against the inlet manifold. It was found that the flow in the inlet manifold exhibits larger recirculation zones. In the investigated range of Ha, Re and θ, the pressure drop coefficient k of the LM MHD flow in the gradual contraction is only slightly lower (< 8 %) than that in the gradual expansion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Performance Assurance Planning Guide for Utility Energy Service Contracts: 2025 Edition

Administered by the U.S. Department of Energy's (DOE) Federal Energy Management Program (FEMP), the Utility Program has fostered collaboration among federal agencies and their serving utilities for more than 25 years. The Utility Program supports agencies using Utility Energy Service Contracts (UESCs), a well-developed, effective contracting vehicle that enable the latest approaches to cost-effective energy management at federal sites. Federal agencies have successfully used UESCs to award over 2,000 energy and water efficiency and renewable energy projects, investing approximately $\$$2.8 billion in furthering the Federal Government's efforts to reduce energy intensity. Authorized by 42 U.S. Code section 8256 (10 U.S. Code section 2913 for the Department of Defense), a UESC is a limited-source acquisition between a federal agency and an eligible serving utility for energy management services that generate savings from the implementation of energy- and water -conservation measures (collectively referred to as ECMs), with 42 U.S. Code section 8287 (Defense Federal Acquisition Regulation Supplement, Part 241), providing the term of a UESC, which may extend up to 25 years. Through a UESC, the utility partner assesses designs, and implements the desired ECMs - which can range from lighting retrofits and renewable energy systems, to combined heat and power plants or other technologies and strategies, and may provide financing for the project. The agency may use any combination of appropriations and third-party financing to pay for the project, providing useful flexibility. There is no limit to the project size, big or small, that can be implemented using a UESC. To assist agencies implementing a UESC, FEMP has developed a Utility Energy Service Contract Guide and this companion guidance document to help agencies and their utility partners better understand the best practices for to ensure UESCs continue to perform and generate savings throughout their performance period. These best practices utilize a combination of effective project management, communication, documentation, and a detailed Performance Assurance Plan. This plan is a project specific set of actionable protocols that define important tasks and responsibilities throughout the contract term and reflects the site conditions, complexities, agency capabilities, and operating and maintaining planned ECMs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Two-Way Option Contracts That Facilitate Adaptive Water Reallocation in the Western United States

Many water markets in the western United States (U.S.) have the ability to reallocate water temporarily during drought, often as short-term water rights leases from lower value irrigated activities to higher value urban uses. Regulatory approval of water transfers, however, typically takes time and involves high transaction costs that arise from technical and legal analyses, discouraging short-term leasing. This leads municipalities to protect against drought-related shortfalls by purchasing large volumes of infrequently used permanent water rights. High transaction costs also result in municipal water rights rarely being leased back to irrigators in wet or normal years, reducing agricultural productivity. This research explores the development of a multi-year two-way option (TWO) contract that facilitates leasing from agricultural-to-urban users during drought and leasing from urban-to agricultural users during wet periods. The modeling framework developed to assess performance of the TWO contracts includes consideration of the hydrologic, engineered, and institutional systems governing the South Platte River Basin in Colorado where there is growing competition for water between municipalities (e.g., the city of Boulder) and irrigators. The modeling framework is built around StateMod, a network-based water allocation model used by state regulators to evaluate water rights allocations and potential rights transfers. Results suggest that the TWO contracts could allow municipalities to maintain supply reliability with significantly reduced rights holdings at lower cost, while increasing agricultural productivity in wet and normal years. Additionally, the TWO contracts provide irrigators with additional revenues via net payments of option fees from municipalities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Analysis of Ground Source Heat Pump ECMs: Implemented Under DOE ESPC IDIQ Contract

Several federal performance and decarbonization objectives are driving the U.S. government to transition to net-zero emissions across the federal building portfolio. The overarching purpose of this Federal Energy Management Program (FEMP)-Geothermal Technologies Office (GTO) work is to support federal facilities in accomplishing the administration’s federal building decarbonization goals. Creating awareness of existing geothermal (or ground-source) heat pump (GHP) systems deployed on federal property, implemented using performance contracts and evaluating the energy and environmental impacts of these systems, this work will assist federal facilities in considering inclusion of GHP technology energy conservation measures (ECMs) in future performance contracting project awards. This report summarizes analyses of data from GHP ECMs installed under the DOE ESPC IDIQ contract across various climate areas and geographic locations, agencies, and building use types. Through the analysis of proposed GHP ECMs and understanding key metrics on implemented GHP systems in a variety of applications, FEMP and GTO can further support federal agencies in meeting decarbonization and net-zero building goals by evaluating and incorporating GHP systems into performance contracts and communicate the benefits of this technology.

15 GEOTHERMAL ENERGY↗
DOE OSTI2026

Performance contracting centers of expertise: a framework for federal implementation

This report examines the establishment and operation of Energy Performance Contracting (EPC) Centers of Expertise (COEs) within the federal government. EPCs, including Energy Savings Performance Contracts (ESPCs) and Utility Energy Service Contracts (UESCs), are critical mechanisms for advancing energy efficiency, resilience, and infrastructure modernization without the need for significant upfront appropriations. However, EPCs require specialized knowledge in project development, contracting, financing, legal parameters and technical project oversight. Currently federal agencies have varying levels of expertise and institutionalized policy to effectively and consistently use congressionally authorized EPCs which have decades of proven and impactful use. To address these challenges, several federal agencies have created COEs to centralize expertise, standardize practices, and streamline implementation. This report reviews statutory and policy drivers, highlights the benefits and challenges and presents case studies from the General Services Administration (GSA), the Department of Veterans Affairs (VA) and the U.S. Army Engineering and Support Center Huntsville (HNC). Recommendations are also provided for agencies considering the establishment of EPC COEs, which will bring much needed structure, consistency and lead to implementation of these energy and infrastructure building projects to save costs for U.S. taxpayers.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1981

Oxidation-induced contraction and strengthening of boron fibers

An investigation of the physical and mechanical effects of thermal treatment in a controlled oxygen-argon atmosphere on boron fibers is reported, with attention to the optimization of such treatment as a secondary processing method for improvement of fiber strength. The strengthening mechanism is comprised of an oxidation-induced axial contraction of the fiber, accompanied by axial compression of strength-limiting flaws within the fiber's tungsten boride core. It was found that after an oxidation contraction of 0.3% near 900 C, and a slight surface etch near 100 C, the average tensile strength of 203-micron fibers increased from 500 to 800 ksi. Various physical observations are used to develop mechanistic models of oxidation, contraction, and the formation of new flaws in the boron sheath at contractions greater than 0.3%.

Dicarlo, J. A.↗
NASA NTRS1983

Rapid distortion of small-scale turbulence by an axisymmetric contraction

The rapid distortion of small-scale turbulence by an axisymmetric internal contracting flow has been investigated. The analysis is an example of the modern version of rapid distortion theory in that the effects of vortex bending and tilting are included. On the axis of symmetry, the classical results are recovered. The longitudinal and lateral velocity components are suppressed and amplified, respectively, with increasing contraction ratio. These effects are enhanced with increasing radial position. The numerical calculations also show that the correlation between the streamwise and radial velocity components increases monotonically with respect to both the radial location and the contraction ratio. The longitudinal and lateral one-dimensional spectra show a shift towards higher and lower wavenumbers, respectively, as the contraction ratio increases. Here, these effects become less pronounced for larger radii. These results also show that the downstream longitudinal integral length scale based on the streamwise velocity as well as the one based on the transverse velocity increase with the radial coordinate.

Hultgren, L. S.↗
NASA NTRS1985

The effect of contraction on a homogeneous turbulent shear flow

In the present study, a homogeneous flow was generated and allowed to reach its asymptotic state. A two-dimensional contraction was inserted a short distance downstream. Both mean velocity and turbulence-stress profiles (normal and shear) were measured at several points along the flow direction. The pressure-strain terms were evaluated from the energy balance made along the wind-tunnel axis. On the basis of the obtained results, it is concluded that a uniformly sheared turbulent flow with approximate transverse homogeneity remains in its condition at all stages of its development through a two-dimensional contraction. Small deviations from homogeneity observed upstream of contraction become much less visible towards the end of contraction. The mean-flow development can be predicted adequately by the Bernoulli equation.

Sreenivasan, K. R.↗
NASA NTRS1985

The application of contraction theory to an iterative formulation of electromagnetic scattering

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

Brand, J. C.↗