Summary of GPC/DV results for space exposed poly(arylene ether phosphine oxide)s

Gel Permeation Chromatography (GPC) was used to analyze poly(arylene ether phosphine oxide)s whose backbones were identical except for the ketone content and placement. These samples were exposed to low Earth orbit environment (predominantly atomic oxygen) on space shuttle flights. The materials and their unexposed controls were then characterized by GPC to investigate the effect of atomic oxygen on the molecular weight distributions. Analysis of the soluble portion of the samples revealed that there was significant loss of high molecular weight species. The presence of insoluble material also suggested that crosslinking was induced by the atomic oxygen exposure and that this very likely occurred at the high molecular weight portion of the molecular weight distribution

A fundamental approach to the sticking of insect residues to aircraft wings

A proposed testing scheme is described for obtaining data on the effects of surface roughness and surface energy on insect adhesion. The road test apparatus is discussed as well as surface preparation techniques. Uncoated and polymer coated metal substrates were analyzed by SEM/ESCA/IRS before and following collision with insects. Critical surface tensions of unexposed Nyebar and poly sulfone coatings were 10 and 33 dynes/cm, respectively, as determined from contact angles. A total of 95% of insect residues collected belong to order Diptera. Significantly less insect debris was detected on the coated plates as compared to the uncoated plates. Minimal contamination at the 5 nm level of both coated and uncoated plates occurs even after hours of exposure to road conditions as determined by ESCA analysis. The presence of nitrogen detected by ESCA on exposed plates is unequivocal evidence for insect residues left on plates

Notational Techniques for Accommodating User Intention Shifts

Good user interface designs allow for user intention shifts. The asynchronous nature of direct maniulation interfaces inherently demands consideration of user intention shifts during the performance of a task. Maintaining a focus on the primary function of a task while at the same time accommodating user intention shifts is difficult for interface designers when both these aspects are represented at the same design level. The User Action Notation (UAN), a technique for representing asynchronous interfaces, contains a mechanism for specifying points in a task where user intention shifts may occur. A complementary technique, Task Transition Diagrams (TTDs), is used to specify tasks that users can perform to interrupt their current task. The Task Transition Diagram is a notation that allows a designer to map out the set of tasks and intentions of users without having to be concerned with the minutiae of how a user accomplishes those tasks

Systems Analysis of Carbon Nanotubes: Opportunities and Challenges for Space Applications

Recent availability of carbon nanotubes (CNTs) in quantities and formats amenable to producing macroscale components invites consideration of these materials in space applications where their attractive properties can enable the realization of bold concepts for affordable space exploration. The challenge is to identify relevant systems and quantify the benefits at the systems level. Before significant investment or adoption of CNTs for large aerospace systems can be justified, there must be a plausible path to attain the perceived systems level benefits. This challenging step requires a close collaboration among experts on CNTs and aerospace system communities. This paper provides an overview of a few relevant potential CNTs applications for space systems and the gap that must be overcome for deployment of CNTs. It also provides a simple engineering-level systems analysis approach to quantify the benefits of using CNTs over state of the art material solutions

Mechanoresponsive Healing Polymers

Methods are provided to produce new mechanoresponsive healing systems. Additionally, various embodiments provide a two tier self-healing material system concept that provides a non-intrusive method to mitigate impact damage in a structure ranging from low velocity impact damage (e.g., crack damage) to high velocity impact damage (e.g., ballistic damage.) The various embodiments provide the mechanophore linked polymer PBG-BCB-PBG. The various embodiments provide methods for synthesizing PBG-BCB-PBG

Computer Analysis of User Interfaces

Interface evaluation is a necessary phase in the production of quality user interfaces. The usual evaluation techniques involve formal experiments or observation, and can be invasive. One non-invasive method that can be used at user sites is to record all user input and system output to a file. This transcript is then algorithmatically analyzed to determine interface problems. A new technique analyzes these transcripts by searching for maximal repeating patterns (MRPs), on the hypothesis that repeating sequences of user actions indicate interesting user behavior, and therefore may show problems in the interface. The technique was tested by using it to evaluate the human-computer interface of a large and complex image processing system in active use. Results show MRPs useful in detecting specific problems within the interface

Net Shaped Aerospace Multifunctional Structures Workshop

No abstract availabl

Structural Nanocomposites for Aerospace Applications

No abstract availabl

Nanotechnology: From Science Fiction to Reality

Nanotechnology promises unconventional solutions to challenging problems because of expectations that matter can be manipulated at the atomic scale to yield properties that exceed those predicted for bulk materials. The excitement at this possibility has been fueled by significant investments in this technology area. This talk will focus on three examples of where advances are being made to exploit unique properties made possible by nanoscale features for aerospace applications. The first two topics will involve the development of carbon nanotubes for (a) lightweight structural applications and (b) net shape fabricated multifunctional components. The third topic will highlight lessons learned from the demonstration of the effect of nanoengineered surfaces on insect residue adhesion. In all three cases, the approaches used to mature these emerging technologies are based on the acceleration of technology development through multidisciplinary collaborations