4,132 research outputs found
Control of a human-powered helicopter in hover
The study of a control system for the Da Vinci 2 human-powered helicopter in hovering flight is documented. This helicopter has two very large, slowly rotating rotor blades and is considered to be unstable in hover. The control system is designed to introduce stability in hover by maintaining level rotors through the use of rotor tip mounted control surfaces. A five degree of freedom kinematic model was developed to study this control system and is documented. Results of this study show that the unaugmented configuration is unstable due to the large Lock Number, and the augmented configuration is stable. The role of NASA in this study included the development and analysis of the kinematic model and control laws. Both analytical and numerical techniques were used
Land Grant Application- Patterson, Joseph (Saco)
Land grant application submitted to the Maine Land Office on behalf of Joseph Patterson for service in the Revolutionary War, by their widow Lucretia.https://digitalmaine.com/revolutionary_war_me_land_office/1706/thumbnail.jp
Superhumps in V348 Pup
The eclipsing novalike cataclysmic variable star V348 Pup exhibits a
persistent luminosity modulation with a period 6 per cent longer than its 2.44
hour orbital-period (Porb). This has been interpreted as a `positive superhump'
resulting from a slowly precessing non-axisymmetric accretion disc
gravitationally interacting with the secondary. We find a clear modulation of
mid-eclipse times on the superhump period, which agrees well with the
predictions of a simple precessing eccentric disc model. Our modelling shows
that the disc light centre is on the far side of the disc from the donor star
when the superhump reaches maximum light. This phasing suggests a link between
superhumps in V348 Pup and late superhumps in SU UMa systems. Modelling of the
full lightcurve and maximum entropy eclipse mapping both show that the disc
emission is concentrated closer to the white dwarf at superhump maximum than at
superhump minimum. We detect additional signals consistent with the beat
periods between the implied disc precession period and both (1/2)Porb and
(1/3)Porb.Comment: 13 pages, 13 figures, accepted for publication in MNRA
A Novel Controlled Release Platform For In Situ Vascular Tissue Engineering
Autologous tissue engineered vascular grafts (TEVGs) are limited by graft stenosis. Small diameter TEVGs implanted as unseeded scaffolds are prone to failure by occlusive luminal proliferation of smooth muscle cells derived from endothelial precursors within a critical period of two weeks. The development, validation, and application novel platform for controlling TEVG performance by local delivery of peptide and/or small molecule therapeutic agents from the TEVG scaffold is presented with insights into the autologous TEVG biology and development.
We hypothesized that inhibition of TGF-βR1 by local delivery of SB-431542, a competitive inhibitor of ALK5/TGFβR1 signaling, is superior to systemic administration of SB-431542 in the prevention of EndMT-mediated neointimal hyperplastic stenosis of a TEVG during the critical period for graft failure in a mouse model. Specific aims included the development of a multiplexed hybrid drug release platform for delivery of small molecule and/or protein species from a TEVG scaffold; validation of the clinical utility of local versus systemic delivery of SB-431542 in the prevention of TEVG neointimal hyperplastic stenosis in a small animal model; and exploration of TGF-β1 signaling in EndMT and TEVG neointimal hyperplastic stenosis.
Local delivery of SB-431542 or recombinant human TGF-β1 prevented stenosis of a small diameter TEVG. Optimization of the local delivery platform achieved maximum therapeutic efficacy with lower costs than systemic therapy. TGF-β1 signaling is central to endothelial-mesenchymal transition in TEVG dysfunction. Translation of this technology for vascular interventional therapy the hypoplastic left heart syndrome has the potential to improve clinical outcomes
Many Key Issues Still Left Unaddressed In the Securities and Exchange Commission\u27s Attempt to Modernize Its Rules of Practice
This Note analyzes and explains the current issues and criticism regarding the SEC’s use of ALJs. In particular, this Note recommends that the SEC ratify its ALJs in accordance with constitutional requirements, create a rigid formula for its forum selection, and amend its Rules of Practice to align more closely to the procedural due process rights in federal district courts. As many of these topics are currently being discussed in federal courts of appeals and within the SEC—through its proposed amendments to the Rules of Practice—this Note intends to add to the discussion on a topic with very little scholarly research. In the SEC’s defense, the SEC’s mission to “protect investors, maintain fair, orderly, and efficient markets, and facilitate capital formation” is a necessary and important mission. Regardless of the mission, individuals are still guaranteed constitutional rights to procedural due process of law when there is a possibility of being “deprived of life, liberty or property .” The first Part of this Note will discuss the historical expansion of the SEC’s enforcement powers. Part II will discuss the current enforcement procedures and the SEC’s recently proposed amendments to its Rules of Practice. Part III will discuss the recent constitutional challenges that defendants have brought against the SEC and the issues regarding subject matter jurisdiction in federal district courts. Part IV will propose three recommendations that the SEC should follow to avoid future criticism of its administrative proceedings
Personality and television program preference
The first step in this process is to define what is implied by the term Uses and Gratifications and to elaborate on current perspectives of the uses and gratifications paradigm in order to understand the need for the present research. As the second step in this process. a discussion of the variable of audience personality will be explored in order to describe why some of the people exhibit different preferences for different television program content. The end result of this discussion on personality and program preference will be a contribution to the body or heuristic knowledge surrounding the reasons for specific television behaviors by the audience
White Dwarf Pulsars
Work on NAG5-3288 ("White Dwarf Pulsars") has been fully integrated with the identically titled project NAG5-4734. The final report below is the same, since the data analysis and interpretative work are integrated, as are the resulting (previous and in-pipeline) publications. The proposal was designed to study pulse and orbital modulations in candidate DQ Herculis stars. Data on 5 stars were obtained. The best results were obtained on YY Draconis, which exhibited a strongly pulsed hard X-ray flux, and even suggested a transition between one-pole and two-pole emission during the course of the observation. This result is being readied for inclusion in a comprehensive study of YY Draconis. A strong pulsation appeared to be present also in H0857-242, but with a period of - 50 minutes, confusion with the first harmonic of the satellite's orbital frequency is possible. So that result is uncertain and is "on ice". A negative result was obtained on 4UO608-49 (V347 Pup), suggesting either that the X-ray identification is incorrect, or that the source is very transient. Finally, data was obtained on V1432 Aql and WZ Sge, respectively the slowest and fastest of these stars. Combined with the ASCA data, the high-energy data demonstrates the latter to contain a white dwarf rotating with P = 27.87 s (Patterson et al. 1998, PASP, 110, 403). Optical photometry contemporaneous with the X-ray data was obtained of V1432 Aql, in order to study the variations in the eclipse waveform. As anticipated, the width and centroid of the eclipse appeared to vary with the 50-day "supercycle"
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