Status of advanced turboprop technology

Research is reviewed in the following areas: turboprop powered transport aircraft; wind tunnel aerodynamic and acoustics tests of model propellers; turboprop maintenance; and wind tunnel tests on airframe-turboprop interactions. Continued development of the technology for advanced turboprop transport was emphasized

Identification and verification of frequency-domain models for XV-15 tilt-rotor aircraft dynamics

Frequency-domain methods are used to extract the open-loop dynamics of the XV-15 tilt-rotor aircraft from flight test data for the cruise condition (V = 170 knots). The frequency responses are numerically fitted with transfer-function forms to identify equivalent model characteristics. The associated handling quality parameters meet or exceed Level 2, Category A, requirements for fixed-wing military aircraft. Step response matching is used to verify the time-domain fidelity of the transfer-function models for the cruise and hover flight conditions. The transient responses of the model and aircraft are in close agreement in all cases, except for the normal acceleration response to elevator deflection in cruise. This discrepancy is probably due to the unmodeled rotor rpm dynamics. The utility of the frequency-domain approach for dynamics identification and analysis is clearly demonstrated

Reparameterization Invariance to all Orders in Heavy Quark Effective Theory

Heavy Quark Effective Theory splits a heavy quark momentum into a large fixed momentum and a variable residual momentum, p = m_Q v + k. It thereby suffers a redundancy of description corresponding to small changes in the choice of the fixed velocity, v. The fact that full QCD is manifestly v-independent should lead to a non-trivial constraint on the form of the effective theory, known as Reparameterization Invariance. For spin-1/2 quarks, the precise form of the constraint and its solution at the level of the effective lagrangian have proven to be rather subtle, and the original proposal by Luke and Manohar has been questioned. In this paper I employ a version of Heavy Quark Effective Theory containing the ``anti-particle'' field as a non-propagating auxiliary field, which greatly simplifies keeping track of v-dependence. This permits a very simple derivation of Reparameterization Invariance from first principles. The auxiliary field can also be integrated out to return to the standard formulation of the effective theory, but with the effective lagrangian now satisfying the full reparameterization constraint. I compare this result with earlier proposals.Comment: 12 pages, LaTex. Important and confusing typographical error in eq. (15) corrected. To appear in Phys. Rev.

Rotational and vibrational effects in ion- dipole collisions

Rotational and vibration effects in ion dipole collisions demonstrated in color motion pictur

The NASA high-speed turboprop program

Technology readiness for Mach 0.7 to 0.8 turboprop powered aircraft with the potential for fuel savings and DOC reductions of up to 30 and 15 percent respectively relative to current in-service aircraft is addressed. The areas of propeller aeroacoustics, propeller structures, turboprop installed performance, aircraft cabin environment, and turboprop engine and aircraft studies are emphasized. Large scale propeller characteristics and high speed propeller flight research tests using a modified testbed aircraft are also considered

Research in development: the approach of AAS

The CGIAR Research Program on Aquatic Agricultural Systems (AAS) is pursuing a Research in Development approach that emphasizes the importance of embedding research in the development context. Reflecting this emphasis the six elements of this approach are a commitment to people and place, participatory action research, gender transformative research, learning and networking, partnerships, and capacity building. It is through the careful pursuit of these six elements that we believe that the program will achieve the development outcomes we aspire to, and do so at scale

In situ stress magnitude and rock strength in the Nankai accretionary complex: a novel approach using paired constraints from downhole data in two wells

We present a method to simultaneously constrain both far-field horizontal stress magnitudes (S hmin and S Hmax) and in situ rock unconfined compressive strength (UCS), using geophysical logging data from two boreholes located 70 m apart that access the uppermost accretionary prism of the Nankai subduction zone . The boreholes sample the same sediments and are affected by the same tectonic stress field, but were drilled with different annular pressures, thus providing a unique opportunity to refine estimates of both in situ stress magnitudes and rock strength. We develop a forward model to predict the angular width of compressional wellbore failures (borehole breakouts), and identify combinations of S Hmax and UCS that best match breakout widths observed in resistivity images from the two boreholes. The method requires knowledge of S hmin, which is defined by leak-off tests conducted during drilling. Our results define a normal to strike-slip stress regime from 900 to 1386 m below seafloor, consistent with observations from seismic and core data. Our analysis also suggests that in situ values of UCS are generally slightly lower that commonly assumed on the basis of published empirical relations between UCS and P-wave velocity

Reduction of leukocyte microvascular adherence and preservation of blood-brain barrier function by superoxide-lowering therapies in a piglet model of neonatal asphyxia

Background: Asphyxia is the most common cause of brain damage in newborns. Substantial evidence indicates that leukocyte recruitment in the cerebral vasculature during asphyxia contributes to this damage. We tested the hypothesis that superoxide radical (O2⋅_) promotes an acute post-asphyxial inflammatory response and blood-brain barrier (BBB) breakdown. We investigated the effects of removing O2⋅_ by superoxide dismutase (SOD) or C3, the cell-permeable SOD mimetic, in protecting against asphyxia-related leukocyte recruitment. We also tested the hypothesis that xanthine oxidase activity is one source of this radical.Methods: Anesthetized piglets were tracheostomized, ventilated, and equipped with closed cranial windows for the assessment of post-asphyxial rhodamine 6G-labeled leukocyte-endothelial adherence and microvascular permeability to sodium fluorescein in cortical venules. Asphyxia was induced by discontinuing ventilation. SOD and C3 were administered by cortical superfusion. The xanthine oxidase inhibitor oxypurinol was administered intravenously.Results: Leukocyte-venular adherence significantly increased during the initial 2 h of post-asphyxial reperfusion. BBB permeability was also elevated relative to non-asphyxial controls. Inhibition of O2⋅_ production by oxypurinol, or elimination of O2⋅_ by SOD or C3, significantly reduced rhodamine 6G-labeled leukocyte-endothelial adherence and improved BBB integrity, as measured by sodium fluorescein leak from cerebral microvessels.Conclusion: Using three different strategies to either prevent formation or enhance elimination of O2⋅_ during the post-asphyxial period, we saw both reduced leukocyte adherence and preserved BBB function with treatment. These findings suggest that agents which lower O2⋅_ in brain may be attractive new therapeutic interventions for the protection of the neonatal brain following asphyxia

Comment on "The Phenomenology of a Nonstandard Higgs Boson in W_L W_L Scattering"

We show that in Composite Higgs models, the coupling of the Higgs resonance to a pair of $W$ bosons is weaker than the corresponding Standard Model coupling, provided the Higgs arises from electroweak doublets only. This is partly due to the effects of the nonlinear realization of the chiral symmetries at the compositeness scale.Comment: 6 pages, BU-HEP 94-2