Manufacturing processes for fabricating graphite/PMR 15 polyimide structural elements

Investigations were conducted to obtain commercially available graphite/PMR-15 polyimide prepreg, develop an autoclave manufacturing process, and demonstrate the process by manufacturing structural elements. Controls were established on polymer, prepreg, composite fabrication, and quality assurance, Successful material quality control and processes were demonstrated by fabricating major structural elements including flat laminates, hat sections, I beam sections, honeycomb sandwich structures, and molded graphite reinforced fittings. Successful fabrication of structural elements and simulated section of the space shuttle aft body flap shows that the graphite/PMR-15 polyimide system and the developed processes are ready for further evaluation in flight test hardware

Military helicopters: have the seeds of future accidents already been sown?

Military helicopters provide ideal conditions for the nucleation and propagation of failure damage. Very few modern machines are expected to perform under such diverse loading and environmental conditions. It is often assumed that failures are a direct consequence of these extreme operating conditions. This paper aims to demonstrate that the originating causes of failure can be introduced at any point in the life of a component, including the design, materials processing, manufacturing or during the service life of the component. Solutions to prevent recurrence of problems cannot be developed without identification of the root cause. Details of four investigations will be presented. Each case study will demonstrate a physical cause residing in an action/inaction occurring during one (or more) of the key life stages of a component, Design, Processing, Manufacture and Service

The Sensewheel: An Adjunct to Wheelchair Skills Training

The purpose of this study was to investigate the influence of real time verbal feedback to optimise push arc during over ground manual wheelchair propulsion. 10 healthy non wheelchair users pushed a manual wheelchair for a distance of 25 metres on level paving, initially with no feedback and then with real time verbal feedback aimed at controlling push arc within a range of 85˚-100˚. The real time feedback was provided by a physiotherapist walking behind the wheelchair, viewing real time data on a tablet personal computer received from the Sensewheel, a lightweight instrumented wheelchair wheel. The real time verbal feedback enabled the participants to significantly increase their push arc. This increase in push arc resulted in a non-significant reduction in push rate and a significant increase in peak force application. The intervention enabled participants to complete the task at a higher mean velocity using significantly fewer pushes. This was achieved via a significant increase in the power generated during the push phase. This study identifies that a lightweight instrumented wheelchair wheel such as the Sensewheel is a useful adjunct to wheelchair skills training. Targeting the optimisation of push arc resulted in beneficial changes in propulsion technique

Agency Design and State Administrators: Political Insulation and Managers’ Views of Their Workplace

This paper examines the impact of agency design upon the perceived workplace conditions within state agencies. The research examines whether insulating features of agency structure such as independent commission status, removal of officers only for cause, and fixed terms for agency leaders are associated with perceptions by state agency managers that their work processes and environments are free of micromanagement and interference from political actors. Data are drawn from the National Administrative Studies Project III, with additional information collected from state agency web sites and statutes. We largely find that administrators working within agencies headed by officials with fixed terms of service believe that top management trusts employees much more than do employees in other agencies. They also have much more pride in the agencies in which they work. We also find that agencies having a commission structure have managers that are perceived to be willing to take risks

Determinants of CO Exposure in the English Housing Stock: Modelling Current and Future Risks

This report investigates the current distribution of low-level CO concentrations in the English housing stock, and prevalence of dwellings exceeding recommended background exposure levels, using advanced modelling techniques informed by empirical data from a number of disparate sources. By bringing these sources of data together in the models, it is possible to produce new insights into the variation in background CO exposure across dwelling types and geographical location. The model also considers the impact on indoor domestic CO concentrations of the application of energy efficiency measures on the same stock. Although the health effects of long-term low-level CO exposure are still uncertain, this report provides evidence for further discussion and research. There are a number of assumptions listed within the main report, that drive the results. These should be taken into consideration when interpreting outcomes

Early growth response gene 2 (Egr-2) controls the self-tolerance of T cells and prevents the development of lupuslike autoimmune disease

© 2008 Zhu et al. This article is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).Maintaining tolerance of T cells to self-antigens is essential to avoid autoimmune disease. How self-reactive T cells are kept functionally inactive is, however, unknown. In this study, we show that early growth response gene 2 (Egr-2), a zinc-finger transcription factor, is expressed in CD44(high) T cells and controls their proliferation and activation. In the absence of Egr-2, CD44(high), but not CD44(low) T cells, are hyperreactive and hyperproliferative in vivo. The accumulation of activated CD4(+)CD44(high) T cells leads to the development of a late onset lupuslike autoimmune disease characterized by the accumulation of interferon (IFN)-gamma and interleukin (IL)-17-producing CD4(+) T cells, loss of tolerance to nuclear antigens, massive infiltration of T cells into multiple organs and glomerulonephritis. We found that the expression of cyclin-dependent kinase inhibitor p21cip1 was impaired in Egr-2-deficient T cells, whereas the expression of IFN-gamma and IL-17 in response to T cell receptor ligation was significantly increased, suggesting that Egr-2 activates the expression of genes involved in the negative regulation of T cell proliferation and inflammation. These results demonstrate that Egr-2 is an intrinsic regulator of effector T cells and controls the expansion of self-reactive T cells and development of autoimmune disease.The Biotechnology and Biological Sciences Research Council, the Medical Research Council and the Wellcome Trust

The effect of sampling techniques used in the multiconfigurational Ehrenfest method

In this paper, we compare and contrast basis set sampling techniques recently developed for use in the ab initio multiple cloning method, a direct dynamics extension to the multiconfigurational Ehrenfest approach, used recently for the quantum simulation of ultrafast photochemistry. We demonstrate that simultaneous use of basis set cloning and basis function trains can produce results which are converged to the exact quantum result. To demonstrate this, we employ these sampling methods in simulations of quantum dynamics in the spin boson model with a broad range of parameters and compare the results to accurate benchmarks

A real-time plant discrimination system utilising discrete reflectance spectroscopy

An advanced, proof-of-concept real-time plant discrimination system is presented that employs two visible (red) laser diodes (635. nm, 685. nm) and one near-infrared (NIR) laser diode (785. nm). The lasers sequentially illuminate the target ground area and a linear sensor array measures the intensities of the reflected laser beams. The spectral reflectance measurements are then processed by an embedded microcontroller running a discrimination algorithm based on dual Normalised Difference Vegetation Indices (NDVI). Pre-determined plant spectral signatures are used to define unique regions-of-classification for use by the discrimination algorithm. Measured aggregated NDVI values that fall within a region-of-classification (RoC) representing an unwanted plant generate a spray control signal that activates an external spray module, thus allowing for a targeted spraying operation. Dynamic outdoor evaluation of the advanced, proof-of-concept real-time plant discrimination system, using three different plant species and control data determined under static laboratory conditions, shows that the system can perform green-from-green plant detection and accomplish practical discrimination for a vehicle speed of 3. km/h