1,191 research outputs found

    Blade row dynamic digital compression program. Volume 2: J85 circumferential distortion redistribution model, effect of Stator characteristics, and stage characteristics sensitivity study

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    The results of dynamic digital blade row compressor model studies of a J85-13 engine are reported. The initial portion of the study was concerned with the calculation of the circumferential redistribution effects in the blade-free volumes forward and aft of the compression component. Although blade-free redistribution effects were estimated, no significant improvement over the parallel-compressor type solution in the prediction of total-pressure inlet distortion stability limit was obtained for the J85-13 engine. Further analysis was directed to identifying the rotor dynamic response to spatial circumferential distortions. Inclusion of the rotor dynamic response led to a considerable gain in the ability of the model to match the test data. The impact of variable stator loss on the prediction of the stability limit was evaluated. An assessment of measurement error on the derivation of the stage characteristics and predicted stability limit of the compressor was also performed

    Blade row dynamic digital compressor program. Volume 1: J85 clean inlet flow and parallel compressor models

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    The results are presented of a one-dimensional dynamic digital blade row compressor model study of a J85-13 engine operating with uniform and with circumferentially distorted inlet flow. Details of the geometry and the derived blade row characteristics used to simulate the clean inlet performance are given. A stability criterion based upon the self developing unsteady internal flows near surge provided an accurate determination of the clean inlet surge line. The basic model was modified to include an arbitrary extent multi-sector parallel compressor configuration for investigating 180 deg 1/rev total pressure, total temperature, and combined total pressure and total temperature distortions. The combined distortions included opposed, coincident, and 90 deg overlapped patterns. The predicted losses in surge pressure ratio matched the measured data trends at all speeds and gave accurate predictions at high corrected speeds where the slope of the speed lines approached the vertical

    Linearized blade row compression component model. Stability and frequency response analysis of a J85-3 compressor

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    NASA developed stability and frequency response analysis techniques were applied to a dynamic blade row compression component stability model to provide a more economic approach to surge line and frequency response determination than that provided by time-dependent methods. This blade row model was linearized and the Jacobian matrix was formed. The clean-inlet-flow stability characteristics of the compressors of two J85-13 engines were predicted by applying the alternate Routh-Hurwitz stability criterion to the Jacobian matrix. The predicted surge line agreed with the clean-inlet-flow surge line predicted by the time-dependent method to a high degree except for one engine at 94% corrected speed. No satisfactory explanation of this discrepancy was found. The frequency response of the linearized system was determined by evaluating its Laplace transfer function. The results of the linearized-frequency-response analysis agree with the time-dependent results when the time-dependent inlet total-pressure and exit-flow function amplitude boundary conditions are less than 1 percent and 3 percent, respectively. The stability analysis technique was extended to a two-sector parallel compressor model with and without interstage crossflow and predictions were carried out for total-pressure distortion extents of 180 deg, 90 deg, 60 deg, and 30 deg

    Conceptual mechanization studies for a horizon definition spacecraft attitude control subsystem, phase A, part II, 10 October 1966 - 29 May 1967

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    Attitude control subsystem for spin stabilized spacecraft for mapping earths infrared horizon radiance profiles in 15 micron carbon dioxide absorption ban

    ARTIFICIAL INTELLIGENCE-ENABLED MULTI-MISSION RESOURCE ALLOCATION TACTICAL DECISION AID

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    The Department of Defense supports many military platforms that execute multiple missions simultaneously. Platforms such as watercraft, aircraft, and land convoys support multiple missions over domains such as air and missile defense, anti-submarine warfare, strike operations, fires in support of ground operations, intelligence sensing and reconnaissance. However, major challenges to the human decision-maker exist in allocating these multi-mission resources such as the growth in battle-tempo, scale, and complexity of available platforms. This capstone study seeks to apply systems engineering to analyze the multi-mission resource allocation (MMRA) problem set to further enable artificial intelligence (AI) and machine learning tools to aid human decision-makers for initial and dynamic re-planning. To approach this problem, the study characterizes inputs and outputs of a potential MMRA process, then analyzes the scalability and complexity across three unique use cases: directed energy convoy protection, aviation support, and a carrier strike group. The critical findings of these diverse use cases were then assessed for similarities and differences to further understand commonalities for a joint AI-enabled MMRA tool.Civilian, Department of the ArmyCivilian, Department of the ArmyCivilian, Department of the NavyApproved for public release. Distribution is unlimited

    Task 4 stage data and performance report for casing treatment investigations. Evaluation of range and distortion tolerance for high Mach number transonic fan stages, volume 2

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    Tabulations of blade element and circumferential distortion flow data in tests of high Mach number transonic fan stages with various rotor tip casing treatment configuration

    Characterisation, expression and ontogeny of interleukin-6 and its receptors in zebrafish (Danio rerio)

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    10 páginas, 8 figuras, 2 tablasInterleukin-6 (IL-6) is one of the most pleiotropic cytokines due to its importance in both innate and adaptive immune responses and other physiological processes. In this study, we identified the zebrafish (Danio rerio) IL-6 homologue by investigating the synteny between the human (Homo sapiens), the fugu (Takifugu rubripes) and the zebrafish genome. Although zebrafish IL-6 showed a low sequence homology with other IL-6 sequences in other species, it presented a high structural similarity to human IL-6. We also analysed IL-6 expression in several different tissues, along with analysis of the expression of the genes that form the IL-6 receptor complex, IL-6R and gp130. After treatment with bacterial or viral stimuli, zebrafish IL-6 expression was modulated in a manner similar to that of other proinflammatory molecules, such as IL-1β and TNF-α. The expression of IL-6, IL-6R and gp130 was also studied during the ontogeny of zebrafish larvae using quantitative PCR and in situ hybridisation. Our results indicated that the transcripts were detected very early, increased during the first week of life and were predominantly expressed in the head, epidermis and neuromasts of the anterior and posterior lateral line system, suggesting their involvement in the normal development of these tissues.We want to thank the funding from the project CSD2007-00002 “Aquagenomics” of the program Consolider-Ingenio 2010 from the Spanish Ministerio de Ciencia e Innovación. M. Varela gratefully acknowledges the JAE Program, co financed by CSIC and European Social Funds, for a predoctoral grant.Peer reviewe

    Optimal control theory for unitary transformations

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    The dynamics of a quantum system driven by an external field is well described by a unitary transformation generated by a time dependent Hamiltonian. The inverse problem of finding the field that generates a specific unitary transformation is the subject of study. The unitary transformation which can represent an algorithm in a quantum computation is imposed on a subset of quantum states embedded in a larger Hilbert space. Optimal control theory (OCT) is used to solve the inversion problem irrespective of the initial input state. A unified formalism, based on the Krotov method is developed leading to a new scheme. The schemes are compared for the inversion of a two-qubit Fourier transform using as registers the vibrational levels of the X1Σg+X^1\Sigma^+_g electronic state of Na2_2. Raman-like transitions through the A1Σu+A^1\Sigma^+_u electronic state induce the transitions. Light fields are found that are able to implement the Fourier transform within a picosecond time scale. Such fields can be obtained by pulse-shaping techniques of a femtosecond pulse. Out of the schemes studied the square modulus scheme converges fastest. A study of the implementation of the QQ qubit Fourier transform in the Na2_2 molecule was carried out for up to 5 qubits. The classical computation effort required to obtain the algorithm with a given fidelity is estimated to scale exponentially with the number of levels. The observed moderate scaling of the pulse intensity with the number of qubits in the transformation is rationalized.Comment: 32 pages, 6 figure

    High brightness inductively coupled plasma source for high current focused ion beam applications

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    A high brightnessplasmaion source has been developed to address focused ion beam(FIB) applications not satisfied by the liquid metal ion source (LMIS) based FIB. The plasmaFIB described here is capable of satisfying applications requiring high mill rates (>100μm³/s) with non-gallium ions and has demonstrated imaging capabilities with sub- 100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasmasource has exhibited a reduced brightness(βr) of 5.4×10³Am⁻²sr⁻¹V⁻¹, with a full width half maximum axial energy spread (ΔE) of 10eV when operated with argon. With xenon, βr=9.1×10³Am⁻²sr⁻¹V⁻¹ and ΔE=7eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30keV and 1pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more amenable to creating high current focused beams, in the regime where spherical aberration dominates the LMIS-FIB. The source has been operated on a two lens ion column and has demonstrated a current density that exceeds that of the LMIS-FIB for current greater than 50nA. Source lifetime and current stability are excellent with inert and reactive gases. Additionally, it should be possible to improve both the brightness and energy spread of this source, such that the (βr/ΔE₂) figure-of-merit could be within an order of magnitude of a LMIS
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