Swarm keeping strategies for spacecraft under J2 and atmospheric drag perturbations

This thesis presents several new open-loop guidance methods for spacecraft swarms comprised of hundreds to thousands of agents with each spacecraft having modest capabilities. These methods have three main goals: preventing relative drift of the swarm, preventing collisions within the swarm, and minimizing the fuel used throughout the mission. The development of these methods progresses by eliminating drift using the Hill-Clohessy-Wiltshire equations, removing drift due to nonlinearity, and minimizing the $J_2$ drift. In order to verify these guidance methods, a new dynamic model for the relative motion of spacecraft is developed. These dynamics are exact and include the two main disturbances for spacecraft in Low Earth Orbit (LEO), $J_2$ and atmospheric drag. Using this dynamic model, numerical simulations are provided at each step to show the effectiveness of each method and to see where improvements can be made. The main result is a set of initial conditions for each spacecraft in the swarm which provides hundreds of collision-free orbits in the presence of $J_2$. Finally, a multi-burn strategy is developed in order to provide hundreds of collision free orbits under the influence of atmospheric drag. This last method works by enforcing the initial conditions multiple times throughout the mission thereby providing collision free motion for the duration of the mission

Knowledge and attitudes of preservice teachers towards students who are gay, lesbian, bisexual, or transgendered.

The study used a survey design to ascertain the levels of knowledge and attitudes of special education and non-special education preservice and inservice teachers towards students with different sexual orientations. The results of this study are based on 408 responses from preservice and inservice teachers enrolled at seven institutions of higher education within North Carolina, Virginia, and the District of Columbia offering teacher training programs in regular and/or special education. Two previously developed instruments were used to measure dependent variables in this study. Koch's modified version of The Knowledge about Homosexuality Questionnaire developep by Harris, Nightengale & Owen was used to measure the dependent variable of the preservice and inservice teacher's knowledge about homosexuality. Herek's Attitudes Toward Lesbians and Gay Men (ATLG) measured the dependent variable of attitudes towards homosexuals. The study found no significant differences reported mean scores for knowledge or attitude of homosexuality among the teacher groups surveyed: (a) special education preservice teachers, (b) non-special education preservice teachers, (c) special education inservice teachers, and (d) non-special education inservice teachers. Neither gender nor age were found to be factors in measures of knowledge or attitude of preservice or inservice teachers. Receiving prior instruction in serving the needs of GLBT students, or with a focus GLBT issues, contributed to higher levels of knowledge and more positive attitudes. This research identified current levels of knowledge and attitudes of preservice and inservice teachers towards GLBT youth, and this information may help outline areas of possible changes necessary in teacher preparation programs, research, and policy

Using Net Groundwater Extractions for Farm Level Groundwater Sustainability Monitoring

The Cal Poly Irrigation Training and Research Center (ITRC) has developed a method for computing net groundwater extraction and recharge at the farm level for district management and regulation of sustainable/safe yields. This method is called Net To/From Groundwater (NTFGW). Net groundwater extraction is preferred for assessing sustainable yield in unconfined aquifer systems over direct metering of gross groundwater pumping. A recent pilot project with the Lower Tule River and Pixley Irrigation Districts’ Groundwater Sustainability Agencies (GSAs) compared actual metered groundwater pumping, surface deliveries, and evapotranspiration to the NTFGW outputs on 19 farms within the GSAs over a 3-year period (2014-2016). In nearly all cases gross metered pumping was greater than net groundwater use, as it should be. In the few instances where this was not the case, intensive investigations identified the issues, which will be presented. The average difference between gross and net groundwater extractions was approximately 14”. The variation of this difference was substantial between farms, indicating the difficulty in using gross pumping from flow/volume metering of actual pumping for sustainability. The NTFGW can incorporate seepage and recharge basin operation on a GSA level. It is also capable of tracking banked groundwater supplies on a farm level

A microscopic simulation laboratory for advanced public transportation system evaluation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.Includes bibliographical references (p. 178-180).by Daniel J. Morgan.S.M

Is there a correlation between infection control performance and other hospital quality measures?

Quality measures are increasingly reported by hospitals to the Centers for Medicare and Medicaid Services (CMS), yet there may be tradeoffs in performance between infection control (IC) and other quality measures. Hospitals that performed best on IC measures did not perform well on most CMS non–IC quality measures