Fernandez J.M.,University of Surrey |
Lappas V.J.,University of Surrey |
Daton-Lovett A.J.,Tech Hampshire
53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 | Year: 2012
This paper presents a novel architecture for solar sails based on the stripped sail concept. In here the beneficial uniaxial tension state in the membrane can still be achieved while minimizing system mass and complexity. For this, the square sail film is completely divided into independent strips parallel to the edges of the sail. The use of lighter open section composite tape springs as the supporting structure is enabled due to the tension provided by the strips that restrict twist and lateral movement. A 2.2m x 2.2m proof-of-concept sail prototype that uses bistable glass fiber tape springs was successfully deployed many times. A larger 5m x 5m sail engineering model has recently being built using 3.6m long bistable carbon fibre tape springs. It has been demonstrated experimentally that two sets of strip attached at the midpoint and tip of the booms provide enough support under gravity. The several advantages of the concept in terms of manufacturability, ease of folding and packing, scalability, space debris hazard reduction and sail shape determination will be presented. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Fernandez J.M.,University of Surrey |
Lappas V.J.,University of Surrey |
Daton-Lovett A.J.,Tech Hampshire
Acta Astronautica | Year: 2011
The Surrey Space Centre is currently working on CubeSail, a 5×5 m2 nano-solar sail spacecraft to be fitted inside a 3U Cubesat platform. The CubeSail mission has a two-fold aim: first, to demonstrate the concept of solar sailing using a 3-axis stabilized sail and second, to demonstrate the potential use of its large membrane as a drag augmentation device for de-orbiting satellites and launch vehicles upper stages in low Earth orbit (LEO). The novel solar sail concept presented here is a result of the highly restrictive area-to-mass ratio and volume constraints imposed by the mission requirements. Therefore, this concept can be readily scaled up to produce future very high performance sailcrafts. Research on ultra-lightweight deployable structures leads to the invention of a new bi-stable composite boom that entails a light and simple deployment subsystem. This simplicity is the key feature that enables the sail to be attached along the length of the booms, thus reducing the structural mass requirement of these support structures. In the completely stripped sail concept the previously considered square or quadrant membrane is split into a set of parallel strips, in order to achieve a uniaxial tension state in the film. Also, a test-bed created for the successful deployment under gravity conditions of the 5 m2 prototype sail is presented. © 2010 Elsevier Ltd. All rights reserved.
Agency: GTR | Branch: EPSRC | Program: | Phase: Research Grant | Award Amount: 2.46M | Year: 2012
The Gas-FACTS programme will provide important underpinning research for UK CCS development and deployment on natural gas power plants, particularly for gas turbine modifications and advanced post combustion capture technologies that are the principal candidates for deployment in a possible tens-of-£billions expansion of the CCS sector between 2020 and 2030, and then operation until 2050 or beyond, in order to meet UK CO2 (carbon dioxide) emission targets. Gas CCS R&D is an emerging field and many of the concepts and underlying scientific principles are still being invented. But on-going UK infrastructure investments and energy policy decisions are being made which would benefit from better information on relevant gas CCS technologies, making independent, fundamental studies by academic researchers a high priority. In addition, the results of this project will provide an essential basis for further work to extract the maximum research benefits from the UK CCS demonstration programme and help to develop more advanced gas CCS technologies for a second tranche of CCS deployment. The programme will also develop rigorous assessment methods and a framework to maximise pathways to impact that could support other RCUK research activities on gas CCS. Globally, there is already interest in gas CCS in Norway, California and the Middle East, and this is likely to become more widespread if cheaper gas leads to more widespread use. This work will be undertaken through work packages with the following aims: WP1: To quantify the scope of gas turbine modifications to improve the technical, environmental and economic performance of integrated CO2 capture on CCGT plants. Small gas turbines will be modified to run with steam or recycled flue gas replacing some of the normal air feed to increase back-end CO2 concentrations (which will help make the CO2 easier to capture). WP2: To quantify through modelling and experimental testing the scope for improving post-combustion capure system performance on CCGT plants through a combination of advanced liquid solvents, including novel amine mixtures, and improved transient performance. Solvents that are used to take up CO2 and then release it in a pure form that can be stored underground will be modified so that the amount of energy required to do this is reduced. The equipment the solvents are used in will also be designed to turn on and off quickly to allow CCS power plants to compensate for fluctuations in output from wind turbines. WP3: In close collaboration with an external Experts Group to undertake integration and whole systems performance assessments. This will include a Gas-FACTS Impact Handbook combining impact tables with state-of-the-art surveys to ensure that pathways to impact pursued by Gas-FACTS researchers are co-ordinated with other significant activities, including excellent science and stakeholder plans, to maximise their effectiveness. Gas-FACTS results will be implemented in the freely-available IECM package for access by any potential users. WP4: Impact delivery and expert interaction activities will be based on establishing an Experts Group including representatives of the UK CCS academic community, global academic community, UK policymakers, UK Regulators, NGOs, power utilities, Original Equipment Manufacturers (OEMs), SMEs (Small and Medium Enterprises). WP4 will also run a programme of engagement activities to impact, including project meetings, specialist meetings on topical issues and results, web-based dissemination and document publication (reports, responses to Parliamentary inquiries, journal papers, articles etc.)
Chaplin R.A.,Tech Hampshire
31st AIAA Applied Aerodynamics Conference | Year: 2013
Lateral reaction jets can be used to control modern weapons and offer faster actuation times than conventional control surfaces. The main disadvantage is the complex interaction flowfield which results between the jet and the crossflow. The aim of this paper is to assess the ability of Computational Fluid Dynamics (CFD) to predict this flowfield for a supersonic lateral jet injected into a transonic crossflow on a flat plate. The predicted jet interaction flowfield was highly sensitive to the turbulence model used, with the Spalart-Allmaras model performing best. The key interaction flow features were well predicted by the CFD across a range of jet pressure ratios and Mach numbers although there were some discrepancies in the predicted jet plume and vortex locations. The predicted results showed that the jet interaction flowfield was relatively insensitive to freestream Mach number.
Cleminson J.R.,Tech Hampshire
AIAA Aerodynamic Decelerator Systems (ADS) Conference 2013 | Year: 2013
The problem of path planning for the precision landing of autonomously-guided parafoil-payload systems is considered for the class of systems that are unpowered and controlled only through the application of lateral steering. The problem is challenging because there is little control over forward speed or descent rate, yet there is strong dependence on wind conditions, which can significantly influence the shape of the trajectory or indeed the feasibility of the problem; there is only one chance at a precision landing. A formulation based on discrete, deterministic Dynamic Programming is proposed to analyse the problem and provide a means of generating feasible trajectories. The formulation accounts for the kinematics of the parafoil in a wind field in a simplified manner to render solutions more tractable and computationally efficient, albeit at the expense of some fidelity. © British Crown Copyright 2013/DSTL.
Reed-Nickerson L.,Tech Hampshire
9th Conference and Exhibition of the SMPTE Australia Section | Year: 2016
This paper is of interest to anyone who is responsible for operating and maintaining a DVB-T (COFDM) transmitter. We examine the OFDM Transmitter starting with the interface to the exciter. We look at data randomizing, Reed-Solomon Coding, Convolutional encoding, Trellis encoding and Viterbi Decoding. Each scheme is described in a simplified matter so the audience will have an understanding how each works. We then explore testing and monitoring methodology and examine how distortions common to the RF sections of a transmitter effect the OFDM signal. The paper also looks at hardware and describes how the manufactures have designed their transmitter. The final part of the paper looks at the recommended DVB-T measurements required to assure optimum performance and coverage, how these measurements should be made, and what is acceptable performance. © 1999 Society of Motion Picture and Television Engineers, Inc.
Orfanoudakis G.I.,University of Southampton |
Yuratich M.A.,Tech Hampshire |
Sharkh S.M.,University of Southampton
IEEE Transactions on Power Electronics | Year: 2013
Nearest vector (NV) modulation strategies for the neutral-point-clamped converter are known to generate low-frequency neutral point (NP) voltage oscillations. Non-NV strategies can eliminate these oscillations, but at the expense of higher switching losses and output voltage harmonic distortion. This letter proposes a simple way of creating hybrid strategies, as combinations of NV and non-NV strategies, which are also able to eliminate NP voltage oscillations. The approach minimizes the participation of non-NV strategies and hence their drawbacks, while it can be applied to any type of load (nonlinear and/or unbalanced). Simulations in MATLAB-Simulink are used to illustrate its operation. © 1986-2012 IEEE.
Brown A.,Tech Hampshire
22nd International Congress on Sound and Vibration, ICSV 2015 | Year: 2015
Free-running ray-trace models operate by repeated calculation of the change in direction of the ray direction using Snell's Law; an iterative technique using small range steps. This process is straightforward, however it has been considered to be computationally inefficient. Faster techniques, using large range steps, have been adopted using assumptions regarding the variation of sound speed in the vertical and horizontal plane. Increased computational speed and memory capacity render the computational inefficiency of free-running ray-trace models largely irrelevant. Hence it is worthwhile revisiting the potential benefits of freerunning ray-trace models with their reduced need for assumptions on sound speed variation. The initial flexibility is in terms of the vertical sound speed profile with the removal of the need for a piecewise linear approximation. Subsequently a free-running ray-trace model can be used to investigate the impact of variation of sound speed with range. Features such as variable wind speed and depth are also readily introduced into free-running ray-trace models.
Agency: GTR | Branch: STFC | Program: | Phase: Research Grant | Award Amount: 8.00K | Year: 2012
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