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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

The origins of the Mithraic mysteries : cosmology and salvation in the ancient world /

Ulansey, David. January 1991 (has links)
Texte remanié de: Diss.--religion--Princeton, 1988. / Bibliogr. p. 141-146. Index.
32

Towards accounting semiology : an interdisciplinary re-conceptualisation of IFRS asset recognition and measurement

Hayoun, Shaul January 2018 (has links)
In the spirit of interdisciplinary critical accounting studies and in light of the IASB’s on-going Conceptual Framework project, this thesis problematises and proposes a re-conceptualisation of two fundamental financial accounting practices: recognition and measurement of assets. In order to do so, the thesis steps outside financial accounting’s conventional disciplinary resources of economics and finance. It proposes to mobilise Ferdinand de Saussure’s semiology, which, defined as a theory of social sign systems, provides a meaningful delineation of financial accounting as a purposeful sign technology. With such a lens and with a research approach of going beyond IASB’s proclaimed concepts and narrative to its nuanced prescriptions, the thesis challenges taken-for-granted assumptions with regard to the market-based nature of Fair Value measurement and the characterisation of judgement involved in recognition. With respect to value measurement, the thesis harness semiology to fracture the dichotomy between the market and the entity perspectives, which is generally assumed in extant accounting research and policy-making. It is shown how the IASB’s Fair Value measurement prescriptions demonstrate semiology's two-dimensional 'value constellation', where the asset’s value is not merely relational (and not intrinsic) but, importantly, relational in two distinct dimensions. It is a product, first, of differentiation from other values in the market and, second, of interrelation with other values in the specific entity. With a semiological theorisation of the financial statement, market-based and entity-specific perspectives serve as complementary inputs rather than contradictory outputs. With respect to recognition, the thesis proposes to shift the locus of judgment from questions of recognition thresholds (probability and reliability) to the under-investigated issue of the asset’s separability from the firm’s general cash flow. It is shown how the IASB’s procedures manifest the semiological principle of ‘reciprocal articulation’: accounting entities (e.g., ‘assets’) are not passive representations of pre-existing economic resources, but rather a product of delimiting – carving out – the asset/resource from the broader category (or the entire firm). With such theorisation, the crux of recognition is separability, which is never natural or technical, but rather anchorless and reciprocal. The thesis thereby sheds light on the plasticity of recognition for both tangible and intangible assets. With its theory-informed analysis the thesis offers a set of conceptual instruments – value constellation and reciprocal articulation – as the logic of the balance sheet as a sign technology: its semio-logic. With Saussure’s ground-breaking linguistic semiology, it offers a parallel financial-numeric semiology: an Accounting Semiology.
33

Optimization of Modulation Constrained Digital Transmission Systems

Han, Yu January 2018 (has links)
The regular waterfilling(WF) policy maximizes the mutual information of parallel channels, when the inputs are Gaussian. However, Gaussian input is ideal, which does not exist in reality. Discrete constellations are usually used instead, such as $ M $-PAM and $ M $-QAM. As a result, the mercury/waterfilling (MWF) policy is introduced, which is a generalization of the regular WF. The MWF applies to inputs with arbitrary distributions, while the regular WF only applies to Gaussian inputs. The MWF-based optimal power allocation (OPA) is presented, for which an algorithm called the internal/external bisection method is introduced. The constellation-constrained capacity is discussed in the thesis, where explicit expressions are presented. The expression contains an integral, which does not have a closed-form solution. However, it can be evaluated via the Monte Carlo method. An approximation of the constellation-constrained capacity based on the sphere packing method is introduced, whose OPA is a convex optimization problem. The CVX was used initially, but it did not generate satisfactory results. Therefore, the bisection method is used instead. Capacities of the MWF and its sphere packing approximation are evaluated for various cases, and compared with each other. It turns out the sphere packing approximation has similar performances to the MWF, which validates the approximation. Unlike the MWF, the sphere packing approximation does not suffer from the loss of precision due to the structure of MMSE functions, which demonstrates its robustness.
34

CubeSat Constellation Analysis for Data Relaying

Smalarz, Bradley Ryan 01 December 2011 (has links)
Current CubeSat communication technology limits the amount of time, and number of accesses with ground stations. It has been proposed to use a constellation of CubeSats to improve relay performance and increase the number of accesses between a CubeSat and ground stations. By using the spatial and temporal analysis features of STK, coupled with the STK/Matlab interface a robust tool was created to analyze the performance of CubeSat constellations based on a store-and-forward communications model which is not currently supported by the STK Engine. Utilizing the Connect messaging format through a socket connection on the local machine, a Matlab graphical user interface, called SATCAT, was constructed in order to provide a user with the ability to control many aspects of the STK Engine externally. A function was created to use three Time Ordered Access (TOA) reports from STK to determine how long it would take for data to be relayed from a target to a ground station through a constellation of CubeSats. Three sample scenarios were created to demonstrate the use and performance analysis capabilities of SATCAT. The performance of a single CubeSat was analyzed and compared to the performance of a three CubeSat constellation and a thirty-seven CubeSat constellation. It was shown that a constellation of three CubeSats decreased the average relay time from 328 minutes to 149 minutes and a constellation of thirty-seven CubeSats further reduced the average relay time to only 3 minutes. While decreasing the average relay time, the constellation of three CubeSats also increased the number of accesses over a twenty-four hour period from 6 to 36, and the constellation of thirty-seven CubeSats allowed for 564 accesses.
35

Scheduling of a Constellation of Satellites: Improving a Simulated Annealing Model by Creating a Mixed-Integer Linear Model

Monmousseau, Philippe January 2015 (has links)
The purpose of this thesis is to provide a new scheduling model of a large constellation of imaging satellites that does not use a heuristic solving method. The objective is to create a mixed-integer linear model that would be competitive in speed and in its closeness to reality against a current model using simulated annealing, while trying to improve both models. Each satellite has the choice between a number of possible events, each event having a utility and a cost, and the chosen schedule must take into account numerous time-related constraints. The main difficulties appeared in modeling realistically a battery level and in handling infeasible configurations due to inaccurate parameters. The obtained linear model has enabled a better understanding of the performance of the simulated annealing solver, and could also be adapted to different real-world scheduling problems.
36

Satellite swarms for auroral plasma science

Parham, Jonathan Brent 28 February 2019 (has links)
With the growing accessibility of space, this thesis work sets out to explore space-based swarms to do multipoint magnetometer measurements of current systems embedded within the Aurora Borealis as an initial foray into concepts for space physics applications using swarms of small spacecraft. As a pathfinder, ANDESITE---a 6U CubeSat with eight deployable picosatellites---was built as part of this research. The mission will fly a local network of magnetometers above the Northern Lights. With the spacecraft due to launch on an upcoming ELaNa mission, here we discuss the details of the science motivation, the mathematical framework for current field reconstruction, the particular hardware implementation selected, the calibration procedures, and the pragmatic management needed to realize the spacecraft. After describing ANDESITE and defining its capability, we also propose a follow-on that uses propulsive nodes in a swarm, allowing measurements that can adaptively change to capture the physical phenomena of interest. To do this a flock of satellites needs to fall into the desired formation and maintain it for the duration of the science mission. A simple optimal controller is developed to model the deployment of the satellites. Using a Monte Carlo approach for the uncertain initial conditions, we bound the fuel cost of the mission and test the feasibility of the concept. To illustrate the system analysis needed to effectively design such swarms, this thesis also develops a framework that characterizes the spatial frequency response of the kilometer-scale filter created by the swarm as it flies through various current density structures in the ionospheric plasma. We then subjugate a nominal ANDESITE formation and the controlled swarm specified to the same analysis framework. The choice of sampling scheme and rigorous basic mathematical analysis are essential in the development of a multipoint-measurement mission. We then turn to a novel capability exploiting current trends in the commercial industry. Magnetometers deployed on the largest constellation to date are leveraged as a space-based magnetometer network. The constellation, operated by Planet Labs Inc., consists of nearly 200 satellites in two polar sun-synchronous orbits, with median spacecraft separations on the order of 375 km, and some occasions of opportunity providing much closer spacing. Each spacecraft contains a magneto-inductive magnetometer, able to sample the ambient magnetic field at 0.1 Hz to 10 Hz with <200 nT sensitivity. A feasibility study is presented wherein seven satellites from the Planet constellation were used to investigate space-time patterns in the current systems overlying an active auroral arc over a 10-minute interval. Throughout the this work advantages, limitations, and caveats in exploiting networks of lower quality magnetometers are discussed, pointing out the path forward to creating a global network that can monitor the space environment.
37

A Look to Burst the Brightest Neon Hearts: Attempts

Fershtman, Eric 01 January 2014 (has links)
A Look to Burst the Brightest Neon Hearts is an inquiry, via constellation of stories diffuse in structure and subject matter, into the various (and really weird) phenomena comprising contemporary American existence. Cumulatively, the stories seek to: (1) kick up, like bottom feeders searching biogenous sediment, an underlying value system, and (2) explore how language both breastfeeds and like, weans this value system-e.g., what dark matter is it that tethers bromances to reality TV? Quantum mechanics to pop music? How can a country be responsible for both the world's highest incarceration rates, and OKCupid? These stories also explore various American conceptions and embodiments of love, plotting out a strange attractor of cultural reflection and refraction.
38

BEIDOU AND GPS DUAL CONSTELLATION VECTOR TRACKING DURING IONOSPHERE SCINTILLATION AT EQUATORIAL REGION

Xu, Dongyang 14 August 2014 (has links)
No description available.
39

Performance Analysis of Asymmetric Constellation in Concatenation with Trellis Coded Modulation for use in Intelligent Systems

Saboowala, Abbas Firoz 22 May 2011 (has links)
No description available.
40

A comparative study of advanced multipath mitigating global positioning system receiver architectures

Kalyanaraman, Sai K. January 1999 (has links)
No description available.

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