Design and application of electromechanical actuators for deep space missions

During the period 8/16/92 through 2/15/93, work has been focused on three major topics: (1) screw modeling and testing; (2) motor selection; and (3) health monitoring and fault diagnosis. Detailed theoretical analysis has been performed to specify a full dynamic model for the roller screw. A test stand has been designed for model parameter estimation and screw testing. In addition, the test stand is expected to be used to perform a study on transverse screw loading

Impact of a Charter School on House Capitalization in a Title I Environment

This study used a mixed-methods approach to determine whether a charter school could influence house capitalization and whether it could induce some families to stay in the school district. It examined home sale values around a charter school in an area covered by underperforming Title I schools. There was a positive but statistically insignificant change in a pre/post comparison of home sale prices, but the increase was consistent with nearby control schools. However, a survey of charter school families found that 25 percent would have left the district had they not been enrolled at the charter school. A plurality said they would leave the district upon completion of their child’s time at the charter school. This study finds that the charter school kept some residents in the school district, but the number of families was not large enough to register in the study of home sales

A St. Joseph Diary of 1839

Reverend Peter Haskew, of the Methodist Episcopal Church, while serving on the “St. Joseph Station and Apalachicola Mission” in 1839 wrote the diary from which extracts follow. It has been edited with notes by Mr. F. W. Hoskins, in whose possession it is. The Reverend Mr. Haskew was born in Alabama in 1803. He was licensed to preach on September 4, 1834. Joining the Alabama Conference on trial in the following December, he was admitted in full connection on January 4, 1837. His first appointment was the Cedar Creek Circuit, Mobile District, for 1835; followed by Monticello, Irwinton District, for 1896; Green, Greensboro District, for 1837; Winchester, Mobile District, for 1838. He was appointed to St. Joseph Station and Apalachicola Mission by the Conference in Montgomery, Alabama, January 4-6, 1839. When he reached St. Joseph is unknown. The day begins on April 24, but possibly earlier leaves have been lost. After leaving St. Joseph near the end of 1839 he served other appointments in the Alabama Conference until 1848 when he was transferred to the Arkansas Conference. Here he served on various appointments and as Presiding Elder until late in 1858 when he located at his own request

The effects of bag style on muscle activity of the trapezius, erector spinae and latissimus dorsi during walking in female university students

© by The Author(s). This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0)Back pain is common in adolescents which has been associated with carrying a bag. However, there is little research examining the effects of bag style in female adolescents. The aim of the study was to investigate the effects of different bag conditions on muscle activity of the trapezius, erector spinae and latissimus dorsi muscles in female university students during walking. Twelve female university students walked on a treadmill for 5 minutes at 1.1 m/s during five conditions; control, 1 strapped rucksack, 2 strapped rucksack, ipsilateral shoulder strap and contralateral shoulder strap, each containing 10% bodyweight. Electromyography for the trapezius, erector spinae and latissimus dorsi was recorded for the last 30 s of each condition. Two-way ANOVA and paired t-tests were used to identify differences between right and left muscles and between bag conditions. Results showed that muscle activity of the left trapezius was significantly higher than the right trapezius during the 1 strap rucksack condition. For the left trapezius, the 2 strapped rucksack and the control condition had significantly lower muscle activity compared to the 1 strapped rucksack and the ipsilateral shoulder strap. For the left erector spinae muscle, there was significantly greater muscle activity when wearing the contralateral shoulder strap compared to the control. For the right erector spinae, significantly lower muscle activity was observed when wearing the 2 strapped rucksack compared to the ipsilateral shoulder strap and contralateral shoulder strap. There were no significant differences in muscle activity of the latissimus dorsi muscles between any of the bag conditions. These findings suggest that a two strapped rucksack should be used when carrying loads to reduce spinal muscle activity which may, in turn, reduce reports of back pain in female adolescentPeer reviewedFinal Published versio

An investigation of teacher change within an intensive art and technology integration project.

Teachers are trying to adapt to many changes in the classroom as they prepare students to become effective learners and contributors in our rapidly advancing technological society. They are also undergoing many learning experiences themselves, as they embrace their own professional development to help prepare them to lead students into the twenty-first century. This study examined some of the changes that teachers encountered while participating in an intensive art and technology integration project. This project, entitled The Community Discovered: The Search for Meaning Through the Integration of Art and Technology in K-12 Education, is a U. S. Department of Education Technology Innovation Challenge Grant. The general mission of this project, and the other Challenge Grants, is to provide a model of innovation in the use of educational technology in today\u27s classroom. The Community Discovered Project seeks to accomplish this through the applied use of new technologies promoting constructivist curricula, interdisciplinary collaboration, and the integration of the arts and technology into core subject areas. This study examined the first year of the project, and sought to identify some of the changes that teachers experienced in their teaching strategies related to: (1) the facilitation of constructivist learning environments; (2) interdisciplinary collaboration for planning and teaching; (3) the incorporation of technology; and (4) the implementation of discipline-based art education. Teacher change is a complex, multifaceted, and ongoing process. Therefore, multiple instruments were used in the process of gathering data. These instruments included surveys, videotape analysis, and classroom based observations. Survey responses indicated that participating teachers had indeed grown in their knowledge and application of constructivist learning, technology, and discipline-based art instruction. Videotapes submitted by teacher participants were also analyzed and scored with a developed rubric. Although some general patterns were noted, specific teacher changes were more difficult to detect in the videotape analysis. Classroom and field observations were also completed and generally supported the survey results. The study results suggested that the professional development directed through The Community Discovered did indeed encourage teachers to initiate personal changes that facilitated constructivist learning, interdisciplinary collaboration, the incorporation of appropriate and effective technology, and the application of Discipline-Based Art Education

Design and application of electromechanical actuators for deep space missions

This progress report documents research and development efforts performed from August 16, 1993 through February 15, 1994 on NASA Grant NAG8-240, 'Design and Application of Electromechanical Actuators for Deep Space Missions.' Following the executive summary are four report sections: Motor Selection, Tests Stand Development, Health Monitoring and Fault Management, and Experiment Planning. Three specific motor types have been considered as prime movers for TVC EMA applications: the brushless dc motor, the permanent magnet synchronous motor, and the induction motor. The fundamental finding was that, in general, the primary performance issues were energy efficiency and thermal dissipation (rotor heating). In terms of all other issues, the three motor types were found to compare quite equally. Among the design changes made to the test stand since the last progress report is the addition of more mounting holes in the side beams. These additional holes allow the movable end beam to be attached in a greater number of positions than previously. With this change the movable end beam can move from full forward to full back in three inch increments. Specific mathematical details on the approach that have been employed for health monitoring and fault management (HMFM) have been reported previously. This approach is based on and adaptive Kalman filter strategy. In general, a bank of filters can be implemented for each primary fault type. Presently under consideration for the brushless dc machine are the following faults: armature winding open-circuits, armature winding short-circuits (phase-to-phase and phase-to-ground), bearing degradation, and rotor flux weakening. The mechanically oriented experiments include transient loading experiments, transverse loading experiment, friction experiment, motor performance experiment, and HMFM experiment

Design and application of electromechanical actuators for deep space missions

This third semi-annual progress report covers the reporting period from August 16, 1994 through February 15, 1995 on NASA Grant NAG8-240, 'Design and Application of Electromechanical Actuators for Deep Space Missions'. There are two major report sections: Motor Control Status/Electrical Experiment Planning and Experiment Planning and Initial Results. The primary emphasis of our efforts during the reporting period has been final construction and testing of the laboratory facilities. As a result, this report is dedicated to that topic

Design and application of electromechanical actuators for deep space missions

The annual report Design and Application of Electromechanical Actuators for Deep Space Missions is presented. The reporting period is 16 Aug. 1992 to 15 Aug. 1993. However, the primary focus will be work performed since submission of our semi-annual progress report in Feb. 1993. Substantial progress was made. We currently feel confident in providing guidelines for motor and control strategy selection in electromechanical actuators to be used in thrust vector control (TVC) applications. A small portion was presented in the semi-annual report. At this point, we have implemented highly detailed simulations of various motor/drive systems. The primary motor candidates were the brushless dc machine, permanent magnet synchronous machine, and the induction machine. The primary control implementations were pulse width modulation and hysteresis current control. Each of the two control strategies were applied to each of the three motor choices. With either pulse width modulation or hysteresis current control, the induction machine was always vector controlled. A standard test position command sequence for system performance evaluation is defined. Currently, we are gathering all of the necessary data for formal presentation of the results. Briefly stated for TVC application, we feel that the brushless dc machine operating under PWM current control is the best option. Substantial details on the topic, with supporting simulation results, will be provided later, in the form of a technical paper prepared for submission and also in the next progress report with more detail than allowed for paper publication

Design and application of electromechanical actuators for deep space missions

This progress report documents research and development efforts performed from August 16, 1993 through August 15, 1994 on NASA Grant NAG8-240, 'Design and Application of Electromechanical Actuators for Deep Space Missions.' Since the submission of our last progress report in February 1994, our efforts have been almost entirely focused on final construction of the test stand and experiment design. Hence, this report is dedicated solely to these topics. However, updates on our research personnel and our health monitoring and fault management efforts are provided in this summary. Following this executive summary are two report sections. The first is devoted to the motor drive being constructed for the test stand. The thrust of the next section is the mechanical and hydraulic design and construction based on the planned experimental requirements. Following both major sections are three appendices