219 research outputs found
An evaluation of the Psychosocial Impact of Assistive Devices Scale
The West Midlands Rehabilitation Centre (WMRC) is responsible for the National Health Service provision and maintenance of Environmental Control Equipment to patients across the West Midlands Region, England. It is important to measure outcome of provision using a paradigm that has meaning for those patients. The Psychosocial Impact of Assistive Devices Scale is a 26-item, self-rating questionnaire designed to measure user perceptions of how assistive devices affect quality of life. This outcome measure is being evaluated in the West Midland
Series of Satellite Encounters to Solve Autonomous Formation Assembly Problem
This paper addresses the problem of bringing two satellites on different orbital planes together and presents results of successful experiment done using two SSTL satellites: UoSat-2 and UoSat-12.A simple linearized Keplerian model with J2 dynamics included was used for initial approximation. A standard LQR controller is presented which by using the above model provides optimal along-track only firing strategy to bring the satellites within a few kilometres of each other. A high precision analytical propagation determines the exact geometry and time of closest approach. As the inclinations of the above two satellites differ by more than 30 degrees, the final step of bringing the two satellites into a stable formation was obviously left out, but radio receiver data from the fly-by are presented to validate the accuracy of the method. A nonlinear least squares filter was constructed to extract orbital elements from the radio data received, thus improving our knowledge of the relative orbits of the two satellites. We have brought the two satellites at closest 7.7 km, while other encounters happened at much larger distances. Clear radio signals were received when the satellites were even 150 km apart. For selected encounters for which we have good quality radio data, we were able to confirm that our prediction was 0.451 second accurate with respect timing and 2.29 km with respect closest approach distance (rms)
Precise Relative Orbit Determination of Low Earth Orbit Formation Flights using GPS Pseudorange and Carrier-Phase Measurements
Formation flying is emerging as an important technology on achieving the tight mission requirements of imaging and remote sensing systems, especially radio interferometry and synthetic aperture radar (SAR) applications. A higher absolute and relative position and orbit knowledge is always sought in these kinds of applications. Such requirements can be met to a large extent by manipulation of GPS data. Carrier-phase Differential GPS (CDGPS) measurements can also be used to further increase the accuracy in relative position and orbit determination dramatically. Using a geometric model has a clear advantage of generality and wide applicability, independent of complex dynamic models for different types of platforms. Hence, the proposed approach uses input from GPS receiver on the master satellite and pseudorange based absolute position estimates from the slave satellites. In addition, single-difference (SD) phase measurements between the master and the slave satellites are also required, which provide very accurate relative distance information. SD information is input into a Kalman filter to determine the relative orbits within the formation to a higher precision. In this paper, we present a geometrical approach to relative orbit determination and present an algorithm for the refinement of position estimates through combining carrier-phase and pseudorange data
Concentrator pointing control concept for fiber optic augmented solar thermal propulsion systems
Concentrator pointing control concept for fiber optic augmented solar thermal propulsion system
Phase Acquisition and Formationkeeping of a New Power Consumption Monitoring Satellite Constellation
A new satellite constellation proposed for global monitoring of electrical power consumption is described in the paper. The optimal small satellite constellation structure as well as its control accuracy required for serving the mission objective throughout the designed life span is examined. The orbital dynamics is analysed for the purposes of optimal phase acquisition and formationkeeping strategy design. A low-cost strategy for spreading all satellites onto their prescribed positions under both time and fuel consumption constraints is explained. The separation errors due to control system uncertainties are analysed, and the system requirements for the constellation phase acquisition are specified. A control strategy is investigated for keeping of the relative pattern of the constellation in spite of the perturbation effects from atmospheric drag and the potential harmonics of the non-spherical Earth, and fuel expenditure is minimised. The system feasibility is demonstrated via simulation results. The control system relies upon low-cost, practical flight-proven sensing and actuating systems for small satellite missions
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Hybrid Manufacturing: Integrating Direct Write and Stereolithography
A commercial stereolithography (SL) machine was modified to integrate fluid dispensing or
direct-write (DW) technology with SL in an integrated manufacturing environment for
automated and efficient hybrid manufacturing of complex electrical devices, combining threedimensional (3D) electrical circuitry with SL-manufactured parts. The modified SL system
operates similarly to a commercially available machine, although build interrupts were used to
stop and start the SL build while depositing fluid using the DW system. An additional linear
encoder was attached to the SL platform z-stage and used to maintain accurate part registration
during the SL and DW build processes. Individual STL files were required as part of the
manufacturing process plan. The DW system employed a three-axis translation mechanism that
was integrated with the commercial SL machine. Registration between the SL part, SL laser and
the DW nozzle was maintained through the use of 0.025-inch diameter cylindrical reference
holes manufactured in the part during SL. After depositing conductive ink using DW, the SL
laser was commanded to trace the profile until the ink was cured. The current system allows for
easy exchange between SL and DW in order to manufacture fully functional 3D electrical
circuits and structures in a semi-automated environment. To demonstrate the manufacturing
capabilities, the hybrid SL/DW setup was used to make a simple multi-layer SL part with
embedded circuitry. This hybrid system is not intended to function as a commercial system, it is
intended for experimental demonstration only. This hybrid SL/DW system has the potential for
manufacturing fully functional electromechanical devices that are more compact, less expensive,
and more reliable than their conventional predecessors, and work is ongoing in order to fully
automate the current system.Mechanical Engineerin
Surface-Based Structure-from-Motion Using Feature Groupings
In this paper we describe a complete system from feature extraction to reconstruction of 3D models of indoor environments. The system uses a novel matching algorithm which matches groupings of features associated with boundaries of objects in the scene. We also present an extension of our structure-from-motion algorithm to incorporate surface constraints. We describe how planar surfaces can be incorporated into the model update procedure, and are hypothesised from the matched groupings of features between image frames. We present reconstructions of environments taken by an autonomous robot to demonstrate the improvement that can be achieved by this approach
Old Ways for New Days
This Open Access book provides a critical reflection into how indigenous cultures are attempting to adapt to climate change. Through detailed first-hand accounts, the book describes the unique challenges facing indigenous peoples in the context of climate change adaptation, governance, communication strategies, and institutional pressures. The book shows how current climate change terminologies and communication strategies often perpetuate the marginalisation of indigenous peoples and suggests that new approaches that prioritise Indigenous voices, agency and survival are required. The book first introduces readers to Indigenous peoples and their struggles related to climate change, describing the impacts of climate change on their everyday lives and the adaptation strategies currently undertaken to address them. These strategies are then detailed through case studies which focus on how Indigenous knowledge and practices have been used to respond to and cope with climate change in a variety of environments, including urban settings. The book discusses specific governance challenges facing Indigenous peoples, and presents new methods for engagement that will bridge existing communication gaps to ensure Indigenous peoples are central to the implementation of climate change adaptation measures. This book is intended for an audience of Indigenous peoples, adaptation practitioners, academics, students, policy makers and government workers. ; Documents for the first time how some of the world's oldest living indigenous cultures are attempting to adapt to climate change Summarizes key issues facing indigenous peoples in the context of adaptation to climate change impacts Offers critical reflection on specific governance challenges faced by indigenous people
Old Ways for New Days
This Open Access book provides a critical reflection into how indigenous cultures are attempting to adapt to climate change. Through detailed first-hand accounts, the book describes the unique challenges facing indigenous peoples in the context of climate change adaptation, governance, communication strategies, and institutional pressures. The book shows how current climate change terminologies and communication strategies often perpetuate the marginalisation of indigenous peoples and suggests that new approaches that prioritise Indigenous voices, agency and survival are required. The book first introduces readers to Indigenous peoples and their struggles related to climate change, describing the impacts of climate change on their everyday lives and the adaptation strategies currently undertaken to address them. These strategies are then detailed through case studies which focus on how Indigenous knowledge and practices have been used to respond to and cope with climate change in a variety of environments, including urban settings. The book discusses specific governance challenges facing Indigenous peoples, and presents new methods for engagement that will bridge existing communication gaps to ensure Indigenous peoples are central to the implementation of climate change adaptation measures. This book is intended for an audience of Indigenous peoples, adaptation practitioners, academics, students, policy makers and government workers. ; Documents for the first time how some of the world's oldest living indigenous cultures are attempting to adapt to climate change Summarizes key issues facing indigenous peoples in the context of adaptation to climate change impacts Offers critical reflection on specific governance challenges faced by indigenous people
A randomized controlled trial of an intervention delivered by mobile phone app instant messaging to increase the acceptability of effective contraception among young people in Tajikistan.
BACKGROUND: Unintended pregnancy is associated with poorer health outcomes for women and their families. In Tajikistan, around 26% of married 15-24 year old women have an unmet need for contraception. There is some evidence that interventions delivered by mobile phone can affect contraceptive-related behaviour and knowledge. We developed an intervention delivered by mobile phone app instant messaging to improve acceptability of effective contraceptive methods among young people in Tajikistan. METHODS: This was a randomized controlled trial among Tajik people aged 16-24. Participants allocated to the intervention arm had access to an app plus intervention messages. Participants allocated to the control arm had access to the app plus control messages. The primary outcome was acceptability of at least one method of effective contraception at 4 months. Secondary outcomes were use of effective contraception at 4 months and during the study, acceptability of individual methods, service uptake, unintended pregnancy and induced abortion. Process outcomes were knowledge, perceived norms, personal agency and intention. Outcomes were analysed using logistic and linear regression. We conducted a pre-specified subgroup analysis and a post-hoc analysis of change in acceptability from baseline to follow-up. RESULTS: Five hundred and seventy-three participants were enrolled. Intervention content was included on the app, causing contamination. Four hundred and seventy-two (82%) completed follow-up for the primary outcome. There was no evidence of a difference in acceptability of effective contraception between the groups (66% in the intervention arm vs 64% in the control arm, adjusted OR 1.21, 95% CI .80-1.83, p = 0.36). There were no differences in the secondary or process outcomes between groups. There was some evidence that the effect of the intervention was greater among women compared to men (interaction test p = 0.03). There was an increase in acceptability of effective contraception from baseline to follow-up (2% to 65%, p < 0.001). CONCLUSIONS: The whole intervention delivered by instant messaging provided no additional benefit over a portion of the intervention delivered by app pages. The important increase in contraceptive acceptability from baseline to follow-up suggests that the intervention content included on the app may influence attitudes. Further research is needed to establish the effect of the intervention on attitudes towards and use of effective contraception among married/sexually active young people. TRIAL REGISTRATION: Clinicaltrial.gov NCT02905513 . Date of registration: 14 September 2016
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