Spacecraft Attitude Maneuver Planning Using Genetic Algorithms

A key enabling technology that leads to greater spacecraft autonomy is the capability to autonomously and optimally slew the spacecraft from and to different attitudes while operating under a number of celestial and dynamic constraints. The task of finding an attitude trajectory that meets all the constraints is a formidable one, in particular for orbiting or fly-by spacecraft where the constraints and initial and final conditions are of time-varying nature. This approach for attitude path planning makes full use of a priori constraint knowledge and is computationally tractable enough to be executed onboard a spacecraft. The approach is based on incorporating the constraints into a cost function and using a Genetic Algorithm to iteratively search for and optimize the solution. This results in a directed random search that explores a large part of the solution space while maintaining the knowledge of good solutions from iteration to iteration. A solution obtained this way may be used as is or as an initial solution to initialize additional deterministic optimization algorithms. A number of representative case examples for time-fixed and time-varying conditions yielded search times that are typically on the order of minutes, thus demonstrating the viability of this method. This approach is applicable to all deep space and planet Earth missions requiring greater spacecraft autonomy, and greatly facilitates navigation and science observation planning

The Impact of GPS Velocity Based Flight Control on Flight Instrumentation Architecture

This thesis explores the use of velocity information obtained by a Global Positioning System (GPS) receiver to close the aircraft’s flight control loop. A novel framework to synthesize attitude information from GPS velocity vector measurements is discussed. The framework combines the benefits of high-quality GPS velocity measurements with a novel velocity vector based flight control paradigm to provide a means for the human operator or autopilot to close the aircraft flight control loop. Issues arising from limitations in GPS as well as the presence of a human in the aircraft control loop are addressed. Results from several flight tests demonstrate the viability of this novel concept and show that GPS velocity based attitude allows for equivalent aircraft control as traditional attitude. Two possible applications of GPS velocity based attitude, an autopilot and a tunnelin- the-sky trajectory guidance system, are demonstrated in flight. Unlike traditional autopilot and trajectory guidance systems, these applications rely solely on the information obtained from a single-antenna GPS receiver which makes them affordable to the larger General Aviation aircraft community. Finally, the impact of GPS velocity based flight control on the instrumentation architecture of flight vehicles is investigated.Rockwell-Collins, NASA/FAA Joint University Program for Air Transportation, Draper Laborator

Impact of Global Positioning System velocity based flight control on flight instrumentation architecture

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 191-195).This thesis explores the use of velocity information obtained by a Global Positioning System (GPS) receiver to close the aircraft's flight control loop. A novel framework to synthesize attitude information from GPS velocity vector measurements is discussed. The framework combines the benefits of high-quality GPS velocity measurements with a novel velocity vector based flight control paradigm to provide a means for the human operator or autopilot to close the aircraft flight control loop. Issues arising from limitations in GPS as well as the presence of a human in the aircraft control loop are addressed. Results from several flight tests demonstrate the viability of this novel concept and show that GPS velocity based attitude allows for equivalent aircraft control as traditional attitude. Two possible applications of GPS velocity based attitude, an autopilot and a tunnel-in- the-sky trajectory guidance system, are demonstrated in flight. Unlike traditional autopilot and trajectory guidance systems, these applications rely solely on the information obtained from a single-antenna GPS receiver which makes them affordable to the larger General Aviation aircraft community. Finally, the impact of GPS velocity based flight control on the instrumentation architecture of flight vehicles is investigated.by Richard P. Kornfeld.Ph.D

Hepatic growth hormone and glucocorticoid receptor signaling in body growth, steatosis and metabolic liver cancer development

Growth hormone (GH) and glucocorticoids (GCs) are involved in the control of processes that are essential for the maintenance of vital body functions including energy supply and growth control. GH and GCs have been well characterized to regulate systemic energy homeostasis, particular during certain conditions of physical stress. However, dysfunctional signaling in both pathways is linked to various metabolic disorders associated with aberrant carbohydrate and lipid metabolism. In liver, GH-dependent activation of the transcription factor signal transducer and activator of transcription (STAT) 5 controls a variety of physiologic functions within hepatocytes. Similarly, GCs, through activation of the glucocorticoid receptor (GR), influence many important liver functions such as gluconeogenesis. Studies in hepatic Stat5 or GR knockout mice have revealed that they similarly control liver function on their target gene level and indeed, the GR functions often as a cofactor of STAT5 for CH-induced genes. Gene sets, which require physical STAT5-GR interaction, include those controlling body growth and maturation. More recently, it has become evident that impairment of GH-STAT5 signaling in different experimental models correlates with metabolic liver disease, ranging from hepatic steatosis to hepatocellular carcinoma (HCC). While GH-activated STAT5 has a protective role in chronic liver disease, experimental disruption of GC-GR signaling rather seems to ameliorate metabolic disorders under metabolic challenge. In this review, we focus on the current knowledge about hepatic CH-STAT5 and GC-GR signaling in body growth, metabolism, and protection from fatty liver disease and HCC development. (c) 2012 Elsevier Ireland Ltd. All rights reserved

Socioeconomic and Geographic Disparities in Health Information Seeking and Internet Use in Puerto Rico

BACKGROUND: Geographically isolated Hispanic populations, such as those living in Puerto Rico, may face unique barriers to health information access. However, little is known about health information access and health information-seeking behaviors of this population. OBJECTIVE: To examine differences in health and cancer information seeking among survey respondents who ever used the Internet and those who did not, and to explore sociodemographic and geographic trends. METHODS: Data for our analyses were from a special implementation of the Health Information National Trends Survey conducted in Puerto Rico in 2009. We collected data through random digit dialing, computer-assisted telephone interviews (N = 639). The sample was drawn from the eight geographic regions of the Puerto Rico Department of Health. To account for complex survey design and perform weighted analyses to obtain population estimates, we analyzed the data using SUDAAN. Frequencies, cross-tabulation with chi-square, and logistic regression analyses were conducted. Geographic information system maps were developed to examine geographic distributions of Internet use and information seeking. RESULTS: Of 639 participants, 142 (weighted percentage 32.7%) indicated that they had ever gone online to access the Internet or World Wide Web; this proportion was substantially lower than that of US mainland Hispanics who reported using the Internet (49%). While 101 of 142 (weighted percentage 59.6%) respondents who used the Web had ever sought health information, only 118 of 497 (weighted percentage 20.0%) of those who did not use the Web had sought health information. The pattern was similar for cancer information: 76 of 142 respondents (weighted percentage 47.2%) who used the Web had ever sought cancer information compared with 105 of 497 (weighted percentage 18.8%) of those who had not used the Web. These results were slightly lower but generally consistent with US mainland Hispanics\u27 health (50.9%) and cancer (26.4%) information seeking. Results of separate logistic regression models controlling for sociodemographic characteristics demonstrated that, compared with individuals who did not seek health or cancer information, those who did were over 5 times as likely to have used the Internet (odds ratio 5.11, P \u3c .001). Those who sought cancer information were over twice as likely to have used the Internet (odds ratio 2.5, P \u3c .05). The frequency of Internet use and health and cancer information seeking was higher in the San Juan metro region than in more rural areas. CONCLUSIONS: Our results contribute to the evidence base for health and cancer communication planning for Puerto Rico, and suggest that health education and outreach efforts should explore the use of available and trusted methods of dissemination such as radio and television, as well as community-based health care providers and organizations, to supplement and encourage use of the Internet as a source of health information

Health and Cancer Information Seeking Practices and Preferences in Puerto Rico: Creating an Evidence Base for Cancer Communication Efforts

Effective communication around cancer control requires understanding of population information seeking practices and their cancer-relevant risk behaviors, attitudes, and knowledge. The Health Information National Trends Survey (HINTS) developed by the U.S. National Cancer Institute (NCI) provides surveillance of the nation's investment in cancer communication tracking the effects of the changing communication environment on cancer-related knowledge, attitudes, and behaviors. The University of Puerto Rico Comprehensive Cancer Center (UPRCCC), the Puerto Rico Behavioral Risk Factors Surveillance System (PRBRFSS), and the NCI implemented HINTS in Puerto Rico in 2009. In this article we describe the health and cancer information seeking behaviors, sources of information, trust in information sources, and experiences seeking information among the population of Puerto Rico. A total of 639 (603 complete and 36 partially complete) interviews were conducted. Nearly one-third of respondents had ever looked for information about health (32.9%) or about cancer (28.1%). The Internet was the most frequently reported source of information. College educated (odds ratio [OR] = 7.6) and females (OR = 2.8) were more likely to seek health information. Similarly, college educated (OR = 5.4) and females (OR = 2.0) were more likely to seek cancer information. Only 32.7% of respondents had ever accessed the Internet, and college educated were more likely to use it (OR = 12.2). Results provide insights into the health and cancer information seeking behaviors and experiences of the population in Puerto Rico and contribute to the evidence base for cancer control planning on the island