A computer module used to calculate the horizontal control surface size of a conceptual aircraft design

The creation of a computer module used to calculate the size of the horizontal control surfaces of a conceptual aircraft design is discussed. The control surface size is determined by first calculating the size needed to rotate the aircraft during takeoff, and, second, by determining if the calculated size is large enough to maintain stability of the aircraft throughout any specified mission. The tail size needed to rotate during takeoff is calculated from a summation of forces about the main landing gear of the aircraft. The stability of the aircraft is determined from a summation of forces about the center of gravity during different phases of the aircraft's flight. Included in the horizontal control surface analysis are: downwash effects on an aft tail, upwash effects on a forward canard, and effects due to flight in close proximity to the ground. Comparisons of production aircraft with numerical models show good accuracy for control surface sizing. A modified canard design verified the accuracy of the module for canard configurations. Added to this stability and control module is a subroutine that determines one of the three design variables, for a stable vectored thrust aircraft. These include forward thrust nozzle position, aft thrust nozzle angle, and forward thrust split

Simple pressure gauge for uranium hexafluoride

A sensitive detector and pressure gauge for uranium hexafluoride in high‐vacuum systems is described. Negative surface ionization of UF_6 occurs on ribbon filaments operated at temperatures too low for electron emission to be significant. The ion current measured on a cylindrical collector surrounding the filament assembly varies regularly with UF_6 pressure below 10^(−3) Torr. Different filament materials are considered, including rhenium, thoriated tungsten, and platinum. Rhenium is found to be the most satisfactory material for operation of diode emitters as a pressure gauge. Gauge constants (in A Torr^(−1)) are derived from comparing negative surface ionization currents with the response of a capacitance manometer and are shown to be independent of temperature within a reasonable operating range. The effects of exposing the rhenium filament to various gases is considered, and it is shown that brief exposure to acetylene substantially improves the operating characteristics of the gauge

\u3ci\u3eAnthidium Oblongatum\u3c/i\u3e (Apoidea: Megachilidae) Confirmed as a Michigan Resident, with Notes on Other Michigan \u3ci\u3eAnthidium\u3c/i\u3e Species

The Palearctic wool-carder bee, Anthidium oblongatum (Illiger) is newly documented in Michigan, with vouchers from Kent, Washtenaw, and Wayne Counties. Additional Michigan records are provided for Anthidium manicatum (L.) and the native Anthidium psoraleae Robertson

Down woody debris microsites for growing black huckleberry shrubs

Black huckleberry (Vaccinium membranaceum) is a shrub in the heather family (Ericaceae) that is ecologically, economically, and culturally important in the Pacific and Inland Northwest. Despite its abundance in many forest environments, black huckleberry requires very specific habitat conditions to successfully establish, grow, and produce berries. Ideal black huckleberry habitat includes a partial canopy (~40% shade) of mature conifers like Douglas-fir or mountain hemlock, often at elevations above approximately 3,000 ft. Because of these specific growing conditions and other factors, black huckleberry has not been commercially cultivated so usually has to be accessed by picking from naturally established shrub fields. As previously burned areas fill in with trees, with fewer new burned areas due to fire suppression efforts and curtailment of Native burning, black huckleberry habitat has declined from the mid-twentieth century forward, putting huckleberry restoration at the forefront of today’s conservation efforts. Our study identified down woody debris (DWD) as a tool to facilitate favorable black huckleberry growing conditions in the absence of one or more of their habitat requirements. This structure occurs naturally in forest environments but can also be supplemented through logging or tree-felling operations, especially with “cull” logs that will not be used for forest products. Recent research has shown that DWD on the forest floor creates small areas of more favorable growing conditions for seedling establishment, known as microsites, compared to surrounding environments

Planning, scheduling, and control for automatic telescopes

This paper presents an argument for the appropriateness of Entropy Reduction Engine (ERE) technology to the planning, scheduling, and control components of Automatic Photoelectric Telescope (APT) management. The paper is organized as follows. In the next section, we give a brief summary of the planning and scheduling requirements for APTs. Following this, in section 3, we give an ERE project precis, couched primarily in terms of project objectives. Section 4 gives a sketch of the match-up between problem and technology, and section 5 outlines where we want to go with this work

The APT/ERE planning and scheduling manifesto

The Entropy Reduction Engine, ERE project, is focusing on the construction of integrated planning and scheduling systems. Specifically, the project is studying the problem of integrating planning and scheduling in the context of the closed loop plan use. The results of this research are particularly relevant when there is some element of dynamism in the environment, and thus some chance that a previously formed plan will fail. After a preliminary study of the APT management and control problem, it was felt that it presents an excellent opportunity to show some of the ERE Project's technical results. Of course, the alignment between technology and problem is not perfect, so planning and scheduling for APTs presents some new and difficult challenges as well