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Results for “Function analysis”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

An exploration of function analysis and function allocation in the commercial flight domain

The applicability is explored of functional analysis methods to support cockpit design. Specifically, alternative techniques are studied for ensuring an effective division of responsibility between the flight crew and automation. A functional decomposition is performed of the commercial flight domain to provide the information necessary to support allocation decisions and demonstrate methodology for allocating functions to flight crew or to automation. The function analysis employed 'bottom up' and 'top down' analyses and demonstrated the comparability of identified functions, using the 'lift off' segment of the 'take off' phase as a test case. The normal flight mission and selected contingencies were addressed. Two alternative methods for using the functional description in the allocation of functions between man and machine were investigated. The two methods were compared in order to ascertain their relative strengths and weaknesses. Finally, conclusions were drawn regarding the practical utility of function analysis methods.

Mcguire, James C.↗
DOE OSTI2015

An Integrated Tool for Functional Requirements Analysis, Function Allocation and Task Analysis

The software application is called "HFE-Trace". This is an integrated method and tool for the management of Human Factors Engineering analyses and related data. Its primary purpose is to support the coherent and consistent application of the nuclear industry's best practices for human factors engineering work. The software is a custom Microsoft® Access® application. The application is used (in conjunction with other tools such as spreadsheets, checklists and normal documents where necessary) to collect data on the design of a new nuclear power plant from subject matter experts and other sources. This information is then used to identify potential system and functional breakdowns of the intended power plant design. This information is expanded by developing extensive descriptions of all functions, as well as system performance parameters, operating limits and constraints, and operational conditions. Once these have been verified, the human factors elements are added to each function, including intended operator role, function allocation considerations, prohibited actions, primary task categories, and primary work station. In addition, the application includes a computational method to assess a number of factors such as system and process complexity, workload, environmental conditions, procedures, regulations, etc.) that may shape operator performance. This is a unique methodology based upon principles described in NUREG/CR-3331 ("A methodology for allocating nuclear power plant control functions to human or automatic control") and it results in a semi-quantified allocation of functions to three or more levels of automation for a conceptual automation system. The aggregate of all this information is then linked to the Task Analysis section of the application where the existing information on all operator functions is transformed into task information and ultimately into design requirements for Human-System Interfaces and Control Rooms. This final step includes assessment of methods to prevent potential operator errors.

Hugo, Jacques↗
DOE OSTI2018

Survival function analysis of planet size distribution with Gaia Data Release 2 updates

Applying the survival function analysis to the planet radius distribution of the Kepler confirmed/candidate planets, we have identified two natural divisions of planet radius at 4 Earth radii (R ⊕ ) and 10 R ⊕ . These divisions place constraints on planet formation and interior structure model. The division at 4 R ⊕ separates small exoplanets from large exoplanets above. When combined with the recently discovered radius gap at 2 R ⊕ , it supports the treatment of planets in between 2 and 4 R ⊕ as a separate group, likely water worlds. For planets around solar-type FGK main-sequence stars, we argue that 2 R ⊕ is the separation between water-poor and water-rich planets, and 4 R ⊕ is the separation between gas-poor and gas-rich planets. Here, we confirm the slope of the survival function in between 4 and 10 R ⊕ to be shallower compared to either ends, indicating a relative paucity of planets in between 4 and 10 R ⊕ , namely the sub-Saturnian desert there. We name them transitional planets, as they form a bridge between the gas-poor small planets and gas giants. Accordingly, we propose the following classification scheme: (<2 R ⊕ ) rocky planets, (2–4 R ⊕ ) water worlds, (4–10 R ⊕ ) transitional planets, and (>10 R ⊕ ) gas giants.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Coupled-cluster Green's function: Analysis of properties originating in the exponential parametrization of the ground-state wave function

In this paper we derive basic properties of the Green’s function matrix elements stemming from the exponential coupled cluster (CC) parametrization of the ground-state wave function. We demon- strate that all intermediates used to express retarded (or equivalently, ionized) part of the Green’s function in the ω-representation can be expressed through connected diagrams only. Similar proper- ties are also shared by the first order ω-derivatives of the retarded part of the CC Green’s function. This property can be extended to any order ω-derivatives of the Green’s function. Through the Dyson equation of CC Green’s function, the derivatives of corresponding CC self-energy can be evaluated analytically. In analogy to the CC Green’s function, the corresponding CC self-energy is expressed in terms of connected diagrams only. Moreover, the ionized part of the CC Green’s func- tion satisfies the non-homogeneous linear system of ordinary differential equations, whose solution may be represented in the exponential form. Our analysis can be easily generalized to the advanced part of the CC Green’s function.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2014

Analysis of and remedies for unphysical ground states of the multireference averaged coupled-pair functional

A Multireference Configuration Interaction (MRCI) wavefunction includes both static and dynamic electron correlation. MRCI's well-known flaw, a lack of size extensivity, can be ameliorated with the Multireference Averaged Coupled-Pair Functional (MRACPF). However, the original MRACPF is frequently unstable, sometimes producing unphysical results. The more Multireference Averaged Quadratic Coupled-Cluster and MRACPF2 functionals also occasionally exhibit unphysical behavior. We find that these instabilities are avoided crossings with unphysical solutions to the MRACPF equations. We present two approaches to avoid the undesirable unphysical solutions.

74 ATOMIC AND MOLECULAR PHYSICS↗