Helicopter low-speed yaw control

A system for improving yaw control at low speeds consists of one strake placed on the upper portion of the fuselage facing the retreating rotor blade and another strake placed on the lower portion of the fuselage facing the advancing rotor blade. These strakes spoil the airflow on the helicopter tail boom during hover, low speed flight, and right or left sidewards flight so that less side thrust is required from the tail rotor

Helicopter Anti-Torque System Using Strakes

A helicopter is disclosed with a system for controlling main-rotor torque which reduces the power and size requirements of conventional anti-torque means. The torque countering forces are generated by disrupting the main rotor downwash flowing around the fuselage. The downwash flow is separated from the fuselage surface by a strake positioned at a specified location on the fuselage. This location is determined by the particular helicopter wash pattern and fuselage configuration, generally being located between 20 deg before top dead center (TDC) and 80 deg from TDC on the fuselage side to which the main rotor blade approaches during rotation. The strake extends along the fuselage from the cabin section to the aft end and can be continuous or separated for aerodynamic surfaces such as a horizontal stabilizer

Two-dimensional aerodynamic characteristics of several polygon-shaped cross-sectional models applicable to helicopter fuselages

A wind-tunnel investigation was conducted to determine 2-D aerodynamic characteristics of nine polygon-shaped models applicable to helicopter fuselages. The models varied from 1/2 to 1/5 scale and were nominally triangular, diamond, and rectangular in shape. Side force and normal force were obtained at increments of angle of flow incidence from -45 to 90 degrees. The data were compared with results from a baseline UH-60 tail-boom cross-section model. The results indicate that the overall shapes of the plots of normal force and side force were similar to the characteristic shape of the baseline data; however, there were important differences in magnitude. At a flow incidence of 0 degrees, larger values of normal force for the polygon models indicate an increase in fuselage down load of 1 to 2.5 percent of main-rotor thrust compared with the baseline value. Also, potential was indicated among some of the configurations to produce high fuselage side forces and yawing moments compared with the baseline model

Time-dependent density functional theory on a lattice

A time-dependent density functional theory (TDDFT) for a quantum many-body system on a lattice is formulated rigorously. We prove the uniqueness of the density-to-potential mapping and demonstrate that a given density is $v$-representable if the initial many-body state and the density satisfy certain well defined conditions. In particular, we show that for a system evolving from its ground state any density with a continuous second time derivative is $v$-representable and therefore the lattice TDDFT is guaranteed to exist. The TDDFT existence and uniqueness theorem is valid for any connected lattice, independently of its size, geometry and/or spatial dimensionality. The general statements of the existence theorem are illustrated on a pedagogical exactly solvable example which displays all details and subtleties of the proof in a transparent form. In conclusion we briefly discuss remaining open problems and directions for a future research.Comment: 12 pages, 1 figur

Geometry-induced pulse instability in microdesigned catalysts: the effect of boundary curvature

We explore the effect of boundary curvature on the instability of reactive pulses in the catalytic oxidation of CO on microdesigned Pt catalysts. Using ring-shaped domains of various radii, we find that the pulses disappear (decollate from the inert boundary) at a turning point bifurcation, and trace this boundary in both physical and geometrical parameter space. These computations corroborate experimental observations of pulse decollation.Comment: submitted to Phys. Rev.

Chapter Three. EED library as a basis for systematic reviews

3.1 Defining Systematic Review Question Priorities 3.2 Determining Relevance to the Systematic Review 3.3 Acquisition of References and Copyright Fair Use Compliance 3.4 Documenting Relevance to the Systematic Review 3.5 Data Extraction for the Systematic Review 3.6 EED Library: Search Results Overview 3.7 Quality Control 3.8 EED Library Statushttps://digitalcommons.wustl.edu/tropicalenteropathybook/1004/thumbnail.jp

Chapter Five. Systematic review results by biomarker classifications

5.1 Markers of Absorption and Permeability Overview 5.2 Markers of Absorption 5.3 Markers of Permeability 5.4 Markers of Digestion 5.5 Markers of Intestinal Inflammation and Intestinal Immune Activation 5.6 Markers of Systemic Inflammation and Systemic Immune Activation 5.7 Markers of Microbial Drivers 5.8 Markers of Nonspecific Intestinal Injury 5.9 Markers of Extra-Small Intestinal Function 5.10 Relationships Between Markers of EED, Including Histopathology 5.11 Relationships between EED Biomarkers and Growth or Other Outcomes of Interesthttps://digitalcommons.wustl.edu/tropicalenteropathybook/1006/thumbnail.jp

Lateral Load Strength of Screw Connections in 29ga Metal

The results of 300 tests on screwed connections in shear are presented. The load capacity of screws in a row is shown to be additive and screws placed in narrow ribs of 29ga steel have the same strength as screws placed in flat sheets. The AISI equation for tilting strength of screw connections under predicts the strength of the screw connections tested. A regression equation is developed for tilting and compared to the AISI tilting equation and a third party test data. The regression equation is more accurate but less precise than the AISI equation