385 research outputs found
Advances in parallel computing technologies and applications/ edited by D. Jude Hemanth, Mohamed Elhosney, Tu N. Nguyen and Sairamesh Lakshmanan.
No full textIncludes index.1 online resourc
Dual-laser frequency-stabilized cavity ring-down spectroscopy for water vapor density measurements
No full textAbsolute measurements of water vapor densities have been carried out using a new concept of frequency-stabilized cavity ring-down spectroscopy. Our scheme is based on the use of a pair of phase-locked extended cavity diode lasers, emitting at 1.39 m, one of them being locked to a self-referenced optical frequency comb synthesizer. An intrinsically stable high-finesse optical cavity that tracks the laser frequency scans has been used. High quality, comb-calibrated, absorption spectra have been recorded in a certified HO/N gas mixture at different gas pressures, in coincidence with the 21transitionoftheHO + band. Water vapor mole fractions have been determined with a statistical uncertainty of 0.6 \%. Systematic deviations have been identified and carefully quantified, thus leading to an overall uncertainty of 0.8 \%
Mechanical properties of aluminium fused SiO2 particulate composites cast using metallic and non-metallic chills
No full textImplementation and verification of energy efficient software for ADCS
No full textThe Delfi-n3Xt was the second nanosatellite developed at the Delft University of Technology, and launched in 2013. Its successor Delfi-PQ is expected to be launched in first half of 2019. The Attitude of a satellite can be referred to as its orientation in space with respect to inertial reference frame. The Delfi-n3Xt was the first satellite from Delft University of Technology, to include three-axis Attitude Determination and Control System/Subsystem (ADCS). It was designed with 5 modes of operation. Four of these were advanced modes. In addition, the Delfi-PQ is not intended to include advanced modes of operation. Hence, this thesis considers using the Delfi-n3Xt ADCS software. This software is extended as a baseline implementation on MSP-EXP432E401Y launchpad. Nearly, 32 % of total nominal power is assigned to ADCS. Hence, energy efficient design alternatives could be considered for future satellite missions. In addition, ADCS is a critical subsystem, failure of ADCS means failure of satellite mission. This thesis aims to improve performance and energy consumption of ADCS. This thesis considers study of three different Digital Signal Processing (DSP) alternatives: Double Precision (DP), Single Precision (SP) and Fixed Point (FxP) arithmetic. Study in this thesis concludes that FxP alternative provides approximately 6.7 times better performance, and approximately 7 times better energy efficiency over baseline. Hence, this thesis proposes the use of FxP DSP alternative. It was also concluded that, the SP arithmetic has equivalent accuracy compared with DP. Moreover, SP provides approximately 3 times better performance, and approximately 2.7 times better energy efficiency over baseline. Therfore, future implementations could benefit from an SP alternative. A major part of the ADCS power is allocated to sensor and actuator. This leaves only 10 % of the total nominal power assigned to ADCS software. Hence, the proposed alternative might not provide considerable improvements on total nominal power. However, for future satellite missions, if there exists a computationally intensive algorithm assigned with more significant amount of total nominal power, then, the proposed alternative could serve as an initial study. However, this does not guarantee that the suggested alternative could satisfy more accurate requirements. In such case, FxP implementation might result in accuracy violation. And use of SP alternative is proposed. In such case, a new study is suggested in order to benefit from FxP alternative.Delfi-PocketQubeElectrical Engineering | Embedded System
On Applications of 3D-Warping and An Analysis of a RANSAC Heuristic
Get PDFIn recent years communication of the scene geometry is gaining importance. With development of technologies such as head mounted displays and Augmented Reality (AR) the need for efficient 3D scene communication is becoming vital. Depth sensors are being incorporated into smartphones for large scale deployment of AR applications. 3D-communication require synchronous capture of the scene from multiple viewpoints along with depth for each view, known as Multiview Plus Depth (MVD) data. The number of views required depends on application. Traditionally, it has been assumed that devices are static but for smartphones such an assumption is not valid. The availability of depth modality opens up several possibilities for efficient MVD data compression. In this work we have leveraged depth for better RGB-D data compression and efficient depth estimation. Using the depth information, the RGB-D device motion can be accurately tracked. 3D-warping along with the camera tracking can then be used to generate reference frames to improve compression efficiency of motion vectors. The same mechanism can be used to predict depth in stereo disparity estimation problem.
For robust tacking of the motion of camera array, we have used the Random Sample Consensus (RANSAC) algorithm. RANSAC is an iterative algorithm for robust model parameter estimation. A common practice among implementations of RANSAC is to take a few samples extra than the minimum required for estimation problem, but the implications of this heuristic is lacking in literature. We present a probabilistic analysis of this common heuristic.
We also present a depth data coding algorithm by employing planar segmentation of depth. While all prior work based on this approach remained restricted to images only and under noise-free conditions, we present an efficient solution for noisy depth videos
The Indian Ocean and Sri Lanka's foreign policy (1948 to 1977) : the development of the zone of Peace concept
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
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