The role of structural dynamics in the design and operations of space systems: The history, the lessons, the technical challenges of the future

Structural dynamics and its auxiliary fields are the most progressive and challenging areas space system engineering design and operations face. Aerospace systems are dependent on structural dynamicists for their success. Past experiences (history) are colored with many dynamic issues, some producing ground or flight test failures. The innovation and creativity that was brought to these issues and problems are the aura from the past that lights the path to the future. Using this illumination to guide understanding of the dynamic phenomena and designing for its potential occurrence are the keys to successful space systems. Our great paradox, or challenge, is how we remain in depth specialists, yet become generalists to the degree that we make good team members and set the right priorities. This paper will deal with how we performed with acclaim in the past, the basic characteristics of structural dynamics (loads cycle, for example), and the challenges of the future

Structural Margins Assessment Approach

A general approach to the structural design and verification used to determine the structural margins of the space vehicle elements under Marshall Space Flight Center (MSFC) management is described. The Space Shuttle results and organization will be used as illustrations for techniques discussed. Given also are: (1) the system analyses performed or to be performed by, and (2) element analyses performed by MSFC and its contractors. Analysis approaches and their verification will be addressed. The Shuttle procedures are general in nature and apply to other than Shuttle space vehicles

Practices in Adequate Structural Design

Structural design and verification of space vehicles and space systems is a very tricky and awe inspiring business, particularly for manned missions. Failures in the missions with loss of life is devastating personally and nationally. The scope of the problem is driven by high performance requirements which push state-of-the-art technologies, creating high sensitivites to small variations and uncertainties. Insurance of safe, reliable flight dictates the use of sound principles, procedures, analysis, and testing. Many of those principles which were refocused by the Space Shuttle Challenger (51-L) accident on January 26, 1986, and the activities conducted to insure safe shuttle reflights are discussed. The emphasis will be focused on engineering, while recognizing that project and project management are also key to success

Assessing Responsiveness to RET by Individuals with Chronic Non-fluent Aphasia: A Clinical Perspective

Response elaboration training (RET) is a “loose training” program designed to increase the length and information content of verbal responses of patients with aphasia (Kearns, 1985). Patients have responded robustly to RET regardless of severity level or type of aphasia (Wambaugh, Wright, and Nessler, 2012). One difficulty faced by clinicians seeking to use RET is participants in research studies have usually been treated at a frequency and for a duration that far exceeds standard clinical practice. In order to examine RET from a “clinical perspective,” the researchers carried out a selective meta-analysis of RET focusing on a “window of treatment” that would be commensurate with standard clinical practice

A new approach for quantifying the effects of response elaboration training

Response Elaboration Training (RET; Kearns, 1985, 1986) is a content-driven treatment for individuals with aphasia. Several studies by Kearns and colleagues indicate RET’s unique “loose training” paradigm increases the amount of verbal information produced by individuals with non-fluent Broca’s aphasia in response to picture stimuli (Gaddie, Kearns, & Yedor, 1991; Kearns, 1985, 1986; Kearns & Scher, 1989; Kearns & Yedor, 1991; Nessler, 2009), and that in some cases, RET effects generalize to other speaking partners, stimuli, and settings (Bennett, Wambaugh, & Nesslar, 2005; Gaddie et al., 1991; Kearns & Yedor, 1991). In most RET research, training effects are quantified by having the participant describe the same pictures used in RET. This provision of pictorial support limits conclusions that can be drawn about the effectiveness of RET and its generalizability. The present study examined the effectiveness and generalizability of RET on speaking performance of individuals with non-fluent Broca’s aphasia with a sentence production task (SPT) that did not provide picture support

Computer Modeling of Graphene Field Effect Transistors

Graphene has been the centerpiece of numerous research projects since its discovery in 2004, greatly due to its multitude of unique properties. Its variable conductivity, relative strength, and electron mobility make graphene a prime candidate for applications in the field of radiation detection. While work has been performed in the past on testing radiation detection using graphene using Graphene Field Effect Transistors (GFET), due to its limited size, fabricating GFETs can be tedious and costly. Therefore, a need arose for a way to test potential GFET designs without the cost and limitations of fabricating GFETs for each test iteration. Using COMSOL Multiphysics, a model of graphene’s material properties and a model of a GFET detector were created to simulate the electric responses. The COMSOL simulation in this project provided data on the responses from the detector, as well as potential scaling information for idealized monolayer single crystal graphene. The results from the computer model are promising; however, experimental work is needed to verify the data. While theoretical information is available on the response of the GFET detector, this data is from an idealized environment based on past empirical and theoretical work. Additional work will need to be performed in the future to compare these results to GFETs in realistic environments

Building Connections to the Minute Man National Historic Park: Greenway Planning and Cultural Landscape Design

The Minute Man National Historic Park (NHP) in Massachusetts commemorates the Battle of Lexington and Concord (1775) that began the American Revolution. The National Park created in 1959 seeks to interpret the battle and restore the agricultural landscapes of the revolutionary period. The Park is situated within the larger Freedom’s Way National Heritage Area (FWNHA) that was designated in 2009 to preserve the extensive historic cultural resources of the region, including such gems as Thoreau’s Walden Pond. Unfortunately, the Minute Man NHP is divided into four units and bisected by a busy state highway that makes wayfinding challenging for visitors. Moreover, the National Trust for Historic Preservation listed the Minute Man NHP “as one of America’s most endangered Places” (NTHP, 2003) due to the impacts of surrounding traffic, noise, and incompatible developments. There are several existing and proposed projects including the Battle Road Trail, Minute Man Bike Trail and Scenic Byway that have the potential to link the Park’s resources, but key connections are missing to create a coherent network. To address these challenges, this project, a partnership between the US National Park Service, FWNHA, and the University of Massachusetts, Amherst uses greenways as an organizing element to improve pedestrian and bike connections from the Park to the many nearby historic, cultural, and recreation resources, while providing visitors an alternative to touring the park by car. An undergraduate landscape architecture studio under the direction of the authors developed a greenway plan for the surrounding area with regional connections, as well as designed key sites and corridors along this greenway network that act as gateways and nodes for cultural and historical interpretation. This project exemplifies the challenges of historic and cultural planning within a developed suburban setting where local and regional recreation demands put pressure on historic landscapes. In addition, the fact that several key sites are outside the jurisdiction of the National Park in municipal, non-profit, or private ownership exemplifies the need for collaborative planning efforts. Finally, the project shows the management issues that continue after designation of historic corridors