| Nonlinear Symplectic Attitude Estimation for Small Satellites |
AUG 2006 |
|
| Authors:
James M. Valpiani; Philip L. Palmer; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
 | A novel method for efficient high-accuracy satellite attitude estimation is presented to address the increasing performance requirements of resource-constrained small satellites. Symplectic numerical methods are applied to the nonlinear estimation problem for Hamiltonian systems, leading to a new general solution that exactly preserves state probability density functions and conserves invariant properties of the dynamics when solving for the state estimate. This nonlinear Symplectic Filter is applied to a standard small ... |
|
| Combined Singularity Avoidance for Variable Speed Control Moment Gyroscope Clusters |
18 APR 2006 |
16 pages |
| Authors:
David J. Richie; Vaios J. Lappas; Sajjad Asghar; Phil L. Palmer; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
 | Variable Speed Control Moment Gyroscopes (VSCMGs), defined by Schaub in [1], effectively applied to combined energy storage and attitude control in [2,3], and further studied by Yoon and Tsiotras in [4,5], can avoid attitude singularities by varying wheel speed. However, this device's key advantage lies in torque amplification via gimballing (i.e. operating in its CMG mode). The primary limitation of this CMG mode, though, is the existence of gimbal-lock singularity ... |
|
| Sizing/Optimization of a Small Satellite Energy Storage and Attitude Control System |
14 APR 2006 |
|
| Authors:
David J. Richie; Vaios J. Lappas; Phil L. Palmer; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The recent advent of miniature single gimbal control moment gyroscopes has spawned interest in variable speed versions for combined energy storage and attitude control systems on small satellites. Although much has been studied on the theory behind such a system, little has been done In optimally sizing these actuators for small satellite applications. Therefore this paper investigates the fundamental design concepts, optimal sizing, and mission benefits for these actuators. Given ... |
|
| A Proposal to Develop and Test a Fibre-Optic Coupled Solar Thermal Propulsion System for Microsatellites |
MAR 2006 |
94 pages |
| Authors:
Paul Henshall; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| This report results from a contract tasking University of Surrey. Solar Thermal Propulsion (STP) previously envisioned for large spacecraft and capable of high levels of propulsive performance ( |
|
| Symplectic Attitude Estimation for Small Satellites |
JAN 2006 |
21 pages |
| Authors:
James M. Valpiani; Phillip L. Palmer; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| In this paper, a novel method for efficient high-accuracy satellite attitude estimation is presented. Symplectic numerical methods are applied to the Extended Kalman Filter (EKF) algorithm to give the SKF, which outperforms the standard EKF in the presence of nonlinearity and low measurement noise in the 1-D case. Building on this result, a six-state SKF is compared to an EKF of the same order for satellite attitude estimation. Simulation of ... |
|
| Super Resolution: An Overview |
25 JUL 2005 |
|
| Authors:
C. Papathanassiou; M. Petrou; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| Super-resolution algorithms produce a single high-resolution image from a set of several, low-resolution images of the desired scene. The low-resolution frames are shifted differently with respect to the high resolution frame with subpixel increments. This paper presents first a theoretical overview of super-resolution algorithms. The most important methods, namely, the iterative back-projection, projection onto convex sets, and maximum a posteriori estimation are then compared within the same framework of implementation. ... |
|
| The Evaluation of Un-Cooled Detectors for Low-Cost Thermal-IR Earth Observation at the Surrey Space Center |
02 FEB 2005 |
5 pages |
| Authors:
Brian Oelrich; Craig Underwood; Stephen Mackin; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| In 2004, the four-micro-satellite Disaster Monitoring Constellation (DMC) became operational. While the constellation currently utilizes visible and near-infrared (IR) imagers, a candidate instrument for future DMC satellites is one operating in the thermal-infrared (TIR). In this research program, a prototype TIR imaging radiometer compatible with the DMC imaging suite was engineered. The 2.5 kg prototype instrument uses a 2-dimensional, commercial- off-the-shelf (COTS) uncooled micro-bolometer array to collect data in any ... |
|
| Solar Thermal Propulsion for Microsatellite Manoeuvring |
SEP 2004 |
|
| Authors:
F. G. Kennedy; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The thesis will trace the development of the microsatellite solar thermal engine from conception through mission analysis design, modelling, fabrication, component, and system testing. On-sun testing of 14-cm and 56-cm diameter solar concentrating mirrors has clearly validated initial optical ray trace modelling and suggests that there is significant performance margin built into test concentrators. Electrical heating tests on two solar cavity receivers the Mk. I and Mk. II, have demonstrated ... |
|
| A Low-Cost Mid-Wave IR Microsatellite Imager Concept Based on Uncooled Technology |
22 JUL 2004 |
10 pages |
| Authors:
Brian D. Oelrich; Arnaud Crastes; Craig I. Underwood; Stephen Mackin; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| A new class of lowcost midwave infrared (MWIR) Earth observation (EO) data will become available with the flight of miniature MWIR EO instruments in satellite constellations. Due to the frequent ground repeat times inherent in constellations, this data set would provide a unique alternative for those wishing to analyse trends or rapidly detect anomalous changes in the MWIR characteristics of the earth's surface (e.g fire detection) or atmosphere. To date, ... |
|
| Low-Cost Satellite Infrared Imager Study |
12 MAR 2004 |
42 pages |
| Authors:
Craig Underwood; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| During the period of this study, the Surrey Space Centre, University of Surrey has conducted a theoretical and laboratory experiment investigation into low-cost thermal infrared imager concepts suitable for flight on very small satellite platforms. The investigation and resulting design concept(s) has emphasized the use of low-cost commercially available components while, at the same time, maximizing performance. The foundation of this research has been based on a commercially available uncooled ... |
|
| Development of a Next Generation Low Power Small Satellite Thruster |
12 MAR 2004 |
28 pages |
| Authors:
David M. Gibbon; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| This report results from a contract tasking Surrey Satellite Technology, Ltd., as follows: The Grantee will investigate the performance trade-offs for micro-satellite propulsion between a next-generation resistojet using xenon propellant and carbon heaters, and other methods. These include existing resistojets and micro-pulsed plasma thrusters. Development and testing of carbon monolith heaters and a prototype thruster will be performed. Pressure and temperature of the gas in stagnation chamber will be measured. ... |
|
| Texture Features That Correlate With the Mini Mental State Examination (MMSE) Score |
25 OCT 2001 |
|
| Authors:
Manuel Segovia-Martinez; Maria Petrou; William Crum; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| We present some 2D and 3D texture features computed from the gray values of MRI-T1 data. The features show strong correlation with the score in the Mini Mental State Examination (MMSE) used routinely to help diagnose Alzheimer's disease. |
|
| Diagnostic Features of Alzheimer's Disease Extracted From FDG Pet Images |
25 OCT 2001 |
|
| Authors:
A. Sayeed; M. Petrou; R. Maguire; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| FDG-PET images of patients suffering from Alzheimers disease (AD) were obtained from Paul Scherre Institute, Villingen, Switzerland. The data were from a CTI/Siemens ECAT 933/04-16 scanner, comprising of 7 image slices 128 x 128 pixels. The study included 48 Clinically diagnosed AD patients and 73 normal controls. Using an invariant feature extraction method features were extracted. The features are invariant to translation and rotation of object(s) within the image. The ... |
|
| Nitrous Oxide Resistojets for Hybrid Rocket Application |
04 JAN 98 |
53 pages |
| Authors:
Malcolm Paul; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| This report results from a contract tasking Surrey Satellite Technology, Ltd. as follows: (1) The contractor will investigate N2O combustion initiation processes in hybrid rockets. (2) A modified resistojet was developed for superheating N2O to initiate hybrid combustion. |
|
| Interconnection of Broadband Islands via Satellite-Experiments on the Race II Catalyst Project |
1996 |
16 pages |
| Authors:
Z. Sun; T. Ors; B. G. Evans; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| This paper presents the performance studies of ATM via satellite based on experiments implemented by the RACE II CATALYST project R2074. The purpose of the project was to develop an ATM satellite link for the future B- ISDN services, particularly for the interconnections of the ATM testbeds which are in the form of broadband islands. Then initial ATM based B-ISDN can be introduced by interconnections ... |
|
| The Three-Dimensional Fourier Series Method for the Calculation of Stress and Strain: Application to Strained-Layer Structures. |
1994 |
|
| Authors:
David A. Faux; Jonathan Gill; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
|
| Automatic Registration of Aerial Photographs and Digitized Maps. |
JUN 1993 |
|
| Authors:
S. Z. Li; J. Kittler; M. Petrou; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| We have developed a method of matching and recognizing aerial road network images based on road network models. The input is a list of line segments of an image obtained from a preprocessing stage, which is usually fragmentary and contains extraneous noisy segments. The output if the correspondences between the image line segments and model line segments. We use attributed relational graphs (ARG) to describe images and models. An ARG ... |
|
| International Symposium on Macrocyclic Ligands for the Design of Ne Materials Held in Guildford, Surrey, UK on September 14 -16, 1992. Programme and Abstracts |
16 SEP 92 |
|
| Authors:
SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| Topics included: Synthetic aspects: Design of Anion Receptors - Applications; Redox-Responsive Ammonium Cation Receptors; Asymmetric Synthesis of Chiral Macrocyclic Ligands; Natural Lypophilic Sequestering Agents; Complexation Properties of Macrocycles Containing Main Group Elements; Tetra- Azamacrocycles Derived from N-Substituted Aromatic Heterocycles: Synthesis and Some Properties; Crown-Ether Phthalocyanines as Alkali-Metal Reagents; Synthesis of a Cu(II) Complex of Macrocyclic Octaamine and its Spectral and Electrochemical Characterisation; New Redox-Active Tetrathiafulvalene and Ferrocene Macrocyclic Receptor Molecules; ... |
|
| Ion Implantation Technology: Proceedings of the International Conference on Ion Implantation Technology (8th) Held at the University of Surrey, Guildford, UK on 30 July - 3 August 1990 |
91 |
|
| Authors:
K. G. Stephens; P. L. Hemment; K. J. Reeson; B. J. Sealy; J. S. Colligon; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The implantation of semiconductor devices as a manufacturing routine is a relatively recent development. But there is a much longer-standing tradition of scientific interest in the production of focussed beams of heavy ions and in the various ways in which they interact with surfaces. This has its origins in Goldstein's 1886 description of Kanalstrahlen in an electric discharge. However, the real significance of this - almost inadvertent - observation of ... |
|
| Workshop on MQW Mixing and its Application to Optoelectronic Devices Held in St. Helier, Jersey on 18-21 September 1990 |
AUG 90 |
|
| Authors:
B. L. Weiss; J. M. Zavada; B. J. Sealy; D. Sadana; M. Littlejohn; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| Partial Contents: GaInAs(P)-InP MQW Mixing by Zn Diffusion, Ge and S Implantation for Optoelectronic Applications, Cation Diffusion in InP/In(0.53) Ga(0.47)As Superlattices: Strain Build-Up and Relaxation, Advanced Materials Characterisation of Electronic Device Structures, Order-Disorder Ternary Alloys by Atomic Layer Epitaxy, Disordering of Superlattices for Laser Applications, Non-Destructive Characterisation of A1As/GaAs Superlattices by Optical Reflection, Disordered Delineated Waveguides in GaA1As/GaAs and GaInAs/InP MQW Structures, Post Growth Tailoring of the Optical Properties of ... |
|
| The Influence of Antistatic Liquid Treatment on the Adhesion of Fresh Coal Fly Ash Particles to Acrylic Fibres, |
1990 |
|
| Authors:
S. V. Rafailidis; J. A. Reizes; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| An experimental study was performed on the effects of antistatic liquid treatment on the deposition of fresh fly ash onto acrylic fibers of fabric filter bags. It was observed that a thin crust of very fine particles was deposited on the treated fibers; and that this crust was not influenced by the material from which the fibers were made. In contrast, on untreated fibers, medium and large particles were deposited. ... |
|
| The Strength of Tungsten-Cored Silicon-Carbide Fibres and the Influence of a Polymer Matrix |
89 |
|
| Authors:
M. G. Bader; D. A. Clarke; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
|
| STATISTICAL INFERENCE ABOUT STRESS CONCENTRATIONS IN FIBRE-MATRIX COMPOSITES. |
1989 |
|
| Authors:
L. C. Wolstenholme; R. L. Smith; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
|
| International Symposium on Solubility Phenomena (3rd) Held in Guildford, Surrey England on 23 - 26 August 1988 |
26 AUG 88 |
|
| Authors:
SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The Six Sessions of the Symposiums Consisted of Presentations of the following Topics: Microcalorimetry and Solubility Studies; Models For Studies of Solutions; Solubility of pollutants an other Inorganic Substances; Thermodynamics and Solubility studies; Solubility of Gases; Macrocyclic Systems and Organic Electrolytes; and Polymers, Miscelles and Miscellaneous Topics. Invited Lectures and Poster Sessions were also presented. Great Britain. (AW) |
|
| The Characterization of Solutes and Solvent Phases |
14 OCT 87 |
|
| Authors:
Michael H. Abraham; Gary S. Whiting; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The characterization of five gas liquid chromatographic stationary phases, using retention data obtained by Laffort and co-workers for 240 solutes, has been carried out by the method of multiple linear regression analysis. Relative gas liquid partition coefficients for as many solutes as possible were correlated against various combinations of parameters. |
|
| A New Method for the Characterization of Solutes and Solvent Phases Using Solvotochromic Parameters |
87 |
|
| Authors:
Michael H. Abraham; Gary S. Whiting; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| Several hundred new secondary log L16 values, obtained by correlation with published data, are presented in this report. Additionally, there are 35 secondary log L16 values from data obtained experimentally on Apiezon L, by the gas chromatographic method and 26 new log L16 values determined directly on hexadecane. These are all collected in Section 1. Now that we have an extended set of parameters, we have repeated the regressions on ... |
|
| THE INDUSTRIAL CONTEXT OF CHEMICAL WARFARE. |
1986 |
|
| Authors:
M. L. BURSTALL; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| THIS PAPER WILL REVIEW THE CURRENT INDUSTRIAL POTENTIAL FOR THE PRODUCTION OF CW AGENTS, AND ATTEMPT TO IDENTIFY FACTORS WHICH ARE DIRECTLY AND INDIRECTLY RELATED TO IT. IT WILL CONSIDER MORE BRIEFLY THE WAYS IN WHICH TECHNICAL CHANGE IN THE FUTURE MIGHT ALTER THE NATURE AND DISTRIBUTION OF THIS CAPACITY. AS FAR AS POSSIBLE A WORLD-WIDE PERSPECTIVE WILL BE ADOPTED, AND POSSIBILITIES OF MONITORING CW ACTIVITY EMPHASIZED. |
|
| Composites in Context |
85 |
|
| Authors:
A. Kelly; SURREY UNIV GUILDFORD (UNITED KINGDOM)
|
| The large scale social changes which influence the development of new materials are reviewed and the new materials and processing methods being developed in response to these are described and contrasted with some recent advances in composite materials science. the particular technologies described are injection casting and superplastic forming, high temperature reinforcement by in situ composites and mechanical alloying. aluminium lithium alloys are compared with carbon fibre reinforced plastics and ... |
|
Reports by Corporate Author
