Experimental study of main rotor tip geometry and tail rotor interactions in hover. Volume 1. Text and figures

A model scale hover test was conducted in the Sikorsky Aircraft Model rotor hover Facility to identify and quantify the impact of the tail rotor on the demonstrated advantages of advanced geometry tip configurations. The test was conducted using the Basic Model Test Rig and two scaled main rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWK and the others a 1/4.71 scale S-76. Eight alternate rotor tip configurations were tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these tips were then selected for testing in close proximity to an operating tail rotor (operating in both tractor and pusher modes) to determine if the performance advantages that could be obtained from the use of advanced geometry tips in a main rotor only environment would still exist in the more complex flow field involving a tail rotor. The test showed that overall the tail rotor effects on the advanced tip configurations tested are not substantially different from the effects on conventional tips

Hybrid perturbation/Bubnov-Galerkin technique for nonlinear thermal analysis

A two step hybrid analysis technique to predict the nonlinear steady state temperature distribution in structures and solids is presented. The technique is based on the regular perturbation expansion and the classical Bubnov-Galerkin approximation. The functions are obtained by using the regular perturbation method. These functions are selected as coordinate functions and the classical Bubnov-Galerkin technique is used to compute their amplitudes. The potential of the proposed hybrid technique for the solution of nonlinear thermal problems is discussed. The effectiveness of this technique is demonstrated by the effects of conduction, convection, and radiation modes of heat transfer. It is indicated that the hybrid technique overcomes the two major drawbacks of the classical techniques: (1) the requirement of using a small parameter in the regular perturbation method; and (2) the arbitrariness in the choice of the coordinate functions in the Bubnov-Galerkin technique. The proposed technique extends the range of applicability of the regular perturbation method and enhances the effectiveness of the Bubnov-Galerkin technique

A Life\u27s Philosophy by D.E. Balch, UND Spring Commencement: June 10, 1952

Text of speech delivered by D.E. Balch at the UND Summer Commencement on June 10, 1952. Balch was the Vice President for Personnel Administration at General Mills in Minneapolis, Minnesota. He entitled his remarks: A Life\u27s Philosophy

Experimental study of main rotor tip geometry and tail rotor interactions in hover. Volume 2: Run log and tabulated data

A model scale hover test was conducted in the Sikorsky Aircraft Model Rotor hover Facility to identify and quantify the impact of the tail rotor on the demonstrated advantages of advanced geometry tip configurations. The existence of mutual interference between hovering main rotor and a tail rotor was acknowledged in the test. The test was conducted using the Basic Model Test Rig and two scaled main rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWK and the others a 1/4.71 scale S-76. Eight alternate rotor tip configurations were tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these tips were then selected for testing in close proximity to an operating tail rotor (operating in both tractor and pusher modes) to determine if the performance advantages that could be obtained from the use of advanced geometry tips in a main rotor only environment would still exist in the more complex flow field involving a tail rotor. This volume contains the test run log and tabulated data

Spatially Extended Dislocations Produced by the Dispersive Swift-Hohenberg Equation

Motivated by previous results showing that the addition of a linear dispersive term to the two-dimensional Kuramoto-Sivashinsky equation has a dramatic effect on the pattern formation, we study the Swift-Hohenberg equation with an added linear dispersive term, the dispersive Swift-Hohenberg equation (DSHE). The DSHE produces stripe patterns with spatially extended dislocations that we call seam defects. In contrast to the dispersive Kuramoto-Sivashinsky equation, the DSHE has a narrow band of unstable wavelengths close to an instability threshold. This allows for analytical progress to be made. We show that the amplitude equation for the DSHE close to threshold is a special case of the anisotropic complex Ginzburg-Landau equation (ACGLE) and that seams in the DSHE correspond to spiral waves in the ACGLE. Seam defects and the corresponding spiral waves tend to organize themselves into chains, and we obtain formulas for the velocity of the spiral wave cores and for the spacing between them. In the limit of strong dispersion, a perturbative analysis yields a relationship between the amplitude and wavelength of a stripe pattern and its propagation velocity. Numerical integrations of the ACGLE and the DSHE confirm these analytical results

Chalk-Ex—fate of CaCO3 particles in the mixed layer : evolution of patch optical properties

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): C07020, doi:10.1029/2008JC004902.The fate of particles in the mixed layer is of great relevance to the global carbon cycle as well as to the propagation of light in the sea. We conducted four manipulative field experiments called “Chalk-Ex” in which known quantities of uniform, calcium carbonate particles were injected into the surface mixed layer. Since the production term for these patches was known to high precision, the experimental design allowed us to focus on terms associated with particle loss. The mass of chalk in the patches was evaluated using the well-calibrated light-scattering properties of the chalk plus measurements from a variety of optical measurements and platforms. Patches were surveyed with a temporal resolution of hours over spatial scales of tens of kilometers. Our results demonstrated exponential loss of the chalk particles with time from the patches. There was little evidence for rapid sinking of the chalk. Instead, horizontal eddy diffusion appeared to be the major factor affecting the dispersion of the chalk to concentrations below the limits of detection. There was unequivocal evidence of subduction of the chalk along isopycnals and subsequent formation of thin layers. Shear dispersion is the most likely mechanism to explain these results. Calculations of horizontal eddy diffusivity were consistent with other mixed layer patch experiments. Our results provide insight into the importance of physics in the formation of subsurface particle maxima in the sea, as well as the importance of rapid coccolith production and critical patch size for maintenance of natural coccolithophore blooms in nature.We would like to thank the Office of Naval Research/Optical and Biological Oceanography Program for their support of Chalk-Ex with awards N000140110042 (WMB) and N00014-01-1-0141 (AJP). Additional funding for this work came from ONR (N00014-05-1- 0111) and NASA (NNG04Gl11G, NNX08AC27G, NNG04HZ25C) to W.M.B

Quantitating the epigenetic transformation contributing to cholesterol homeostasis using Gaussian process.

To understand the impact of epigenetics on human misfolding disease, we apply Gaussian-process regression (GPR) based machine learning (ML) (GPR-ML) through variation spatial profiling (VSP). VSP generates population-based matrices describing the spatial covariance (SCV) relationships that link genetic diversity to fitness of the individual in response to histone deacetylases inhibitors (HDACi). Niemann-Pick C1 (NPC1) is a Mendelian disorder caused by >300 variants in the NPC1 gene that disrupt cholesterol homeostasis leading to the rapid onset and progression of neurodegenerative disease. We determine the sequence-to-function-to-structure relationships of the NPC1 polypeptide fold required for membrane trafficking and generation of a tunnel that mediates cholesterol flux in late endosomal/lysosomal (LE/Ly) compartments. HDACi treatment reveals unanticipated epigenomic plasticity in SCV relationships that restore NPC1 functionality. GPR-ML based matrices capture the epigenetic processes impacting information flow through central dogma, providing a framework for quantifying the effect of the environment on the healthspan of the individual

Experimental study of main rotor/tail rotor/airframe interactions in hover. Volume 1: Text and figures

To assist in identifying and quantifying the relevant parameters associated with the complex topic of main rotor/fuselage/tail rotor interference, a model scale hover test was conducted in the Model Rotor Hover Facility. The test was conducted using the basic model test rig, fuselage skins to represent a UH-60A BLACK HAWK helicopter, 4 sets of rotor blades of varying geometry (i.e., twist, airfoils and solidity) and a model tail rotor that could be relocated to give changes in rotor clearance (axially, laterally, and vertically), can't angle and operating model (pusher or tractor). The description of the models and the tests, data analysis and summary (including plots) are included. The customary system of units gas used for principal measurements and calculations. Expressions in both SI units and customary units are used with the SI units stated first and the customary units afterwords, in parenthesis