Control System Optimization for Saturn 5 Launch Vehicles Using Gradient Techniques Final Report

Control system optimization for Saturn 5 launch vehicles using gradient technique

The application of optimal control technqiues to advanced manned missions, volume 1

Two problems are presented in the area of optimal control and its application to the design of attitude control systems for advanced complex aerospace vehicles. The problems discussed are specification of performance criteria in terms of structural load minimization and/or maximum orbital payload injection requirements of the controlled vehicle; and formulation and solution of the optimization problem such that practical control systems are obtained

A study for development of aerothermodynamic test model materials and fabrication technique

A literature survey, materials reformulation and tailoring, fabrication problems, and materials selection and evaluation for fabricating models to be used with the phase-change technique for obtaining quantitative aerodynamic heat transfer data are presented. The study resulted in the selection of two best materials, stycast 2762 FT, and an alumina ceramic. Characteristics of these materials and detailed fabrication methods are presented

Low altitude temperature and humidity profile data for application to aircraft noise propagation

A data search of the weather statistics from 11 widely dispersed geographical locations within the continental United States was conducted. The sites, located long both sea-coasts and in the interior, span the northern, southern, and middle latitudes. The weather statistics, retrieved from the records of these 11 sites, consist of two daily observations taken over a 10-year period. The data were sorted with respect to precipitation and surface winds and classified into temperature intervals of 5 C and relative humidity intervals of 10 percent for the lower 1400 meters of the atmosphere. These data were assembled in a statistical format and further classified into altitude increments of 200 meters. The data are presented as sets of tables for each site by season of the year and include both daily observations

Noise characteristics of the O-1 airplane and some approaches to noise reduction

A brief study of the O-1A airplane to determine possible means for reducing the aircraft aural detection distance was conducted. This effort involved measuring the noise signature of the basic airplane, devising methods to attenuate the noise, and then estimating the effect of several selected modifications on the aural detection distance of the aircraft. A relatively simple modification utilizing a 6.5 ft diameter, six-blade propeller and including a muffler having a volume of 0.725 cu ft is indicated to reduce the aural detection distance of the O-1 aircraft from about 6 miles at an altitude of 1,000 ft and 2 to 3 miles at an altitude of 300 ft to approximately half these values. The flyover noise data suggest that routing the exhaust stacks up and over the wing would provide immediate noise reduction of about 5 dB with an attendant reduction in detection distance. Furthermore, all these studies confirm the work of other investigators that the 1/3 octave band (center frequency=125 cps) is the most critical in reducing aural detection distance

The application of optimal control techniques to advanced manned missions, volume 2

The hybrid optimization techique for attitude control design is described in detail. The technque is capable of optimizing an n-dimensional adjustable parameter vector, but a 1-dimensional vector is used as an example to explain the procedure. This permits an easier explanation as opposed to a multidimensional case. The procedure used to derive the perturbation equations of motion describing the 6-DOF shuttle ascent phase is presented. These equations were programmed on the EAI 8800 analog computer to describe the perturbations of the shuttle vehicle from a nominal zero lift trajectory due to wind disturbances. Included are the control system equations, trim equations, and wind angle of attack equations. Analog wiring diagrams, raw data and time-varying coefficients, and state variable responses during shuttle ascent are also considered

Noise reduction studies for the OV-1 airplane

A study has been conducted to define possible modifications to the OV-1 aircraft to reduce its aural detection distance. This effort involved documenting the noise characteristics of the airplane, devising modifications to reduce the noise, estimating the reduction in detection distance, and evaluating aircraft performance as a result of these modifications. It was found that the main noise source on this aircraft is the propeller and hence modifications only to the propeller and the propeller drive system are proposed. Modifications involving only the propeller are noted to involve no increase in weight but they result in only a modest decrease in aural detection distance. In order to obtain substantial decreases in aural detection distance, modifications involving changes both to the propeller and the engine-propeller gearing are required

Dental safety net capacity: An innovative use of existing data to measure dentists’ clinical engagement in state Medicaid programs

Background The demand for dentists available for state Medicaid populations has long outpaced the supply of such providers. To help understand the workforce dynamics, this study sought to develop a novel approach to measuring dentists’ relative contribution to the dental safety net and, using this new measurement, identify demographic and practice characteristics predictive of dentists’ willingness to participate in Indiana's Medicaid program. Methods We examined Medicaid claims data for 1,023 Indiana dentists. We fit generalized ordered logistic regression models to measure dentists’ level of clinical engagement with Medicaid. Using a partial proportional odds specification model, we estimated proportional adjusted odds ratios for covariates and separate estimates for each contrast of nonproportional covariates. Results Though 75% of Medicaid‐enrolled dentists were active providers, only 27% of them had 800 or more claims during fiscal year 2015. As has been shown in previous studies, our findings from the proportional odds model reinforced certain demographic and practice characteristics to be predictive of dentists’ participation in state Medicaid programs. Conclusions In addition to confirming predictive factors for Medicaid enrollment, this study validated the clinical engagement measure as a reliable method to assess the level of Medicaid participation. Prior studies have been limited by self‐reported data and variations in Medicaid claims reporting

State policy environment and the dental safety net: a case study of professional practice environments’ effect on dental service availability in Federally Qualified Health Centers

Objectives To determine whether and to what extent the state policy environment for the dental hygiene workforce affects the availability of dental services at Federally Qualified Health Centers (FQHCs). Methods We examined data drawn from the Uniform Data System on 1,135 unique FQHC grantees receiving community health center funding from the U.S. Health Center program between 2004 and 2012. The Dental Hygiene Professional Practice Index was used to quantify variations in state policy environment. We then examined the influence of state policy environment on the availability of dental care through generalized linear mixed-effects models. Results Approximately 80% of FQHCs reported delivering dental services. We consistently observed that FQHCs with favorable levels of state support had the highest proportion of FQHCs that delivered dental services, even more so than FQHCs with extremely high support. FQHCs located in the most restrictive states had 0.28 the odds of delivering dental services as did those located in the most supportive states. Conclusions The state policy environment for the dental hygiene workforce is likely associated with the availability of dental services at FQHCs. The greatest proportion of FQHCs delivering dental services was found in states with policy provisions supporting professional independence in public health settings. Nevertheless, additional research is needed to understand the specific mechanism by which these policies affect FQHCs

A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed

The question of whether galaxy mergers are linked to the triggering of active galactic nuclei (AGN) continues to be a topic of considerable debate. The issue can be broken down into two distinct questions: 1) Can galaxy mergers trigger AGN? 2) Are galaxy mergers the dominant AGN triggering mechanism? A complete picture of the AGN-merger connection requires that both of these questions are addressed with the same dataset. In previous work, we have shown that galaxy mergers selected from the Sloan Digital Sky Survey (SDSS) show an excess of both optically-selected, and mid-IR colour-selected AGN, demonstrating that the answer to the first of the above questions is affirmative. Here, we use the same optical and mid-IR AGN selection to address the second question, by quantifying the frequency of morphological disturbances in low surface brightness r-band images from the Canada France Imaging Survey (CFIS). Only ~30 per cent of optical AGN host galaxies are morphologically disturbed, indicating that recent interactions are not the dominant trigger. However, almost 60 per cent of mid-IR AGN hosts show signs of visual disturbance, indicating that interactions play a more significant role in nuclear feeding. Both mid-IR and optically selected AGN have interacting fractions that are a factor of two greater than a mass and redshift matched non-AGN control sample, an excess that increases with both AGN luminosity and host galaxy stellar mass.Comment: Accepted for publication in MNRA