3,082 research outputs found

    On the Calculation of the Exponential Bound Parameter for Phase Quantized 8-PSK

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    The exponential bound parameter is numerically evaluated for 16-zone quantized 8-PSK for signal vectors bisecting decision regions and for signal vectors lying on decision boundaries. For decision regions of equal span, signal vectors lying on decision boundaries are superior, confirming the result of Parsons and Wilson (1990). Signal vectors bisecting decision regions are superior if span of decision regions not containing signal vectors is optimized. Using the partial derivative, it is shown that the optimal configuration depends on SNR. Furthermore, the optimal configuration is not necessarily one in which the decision boundaries are straight lines

    Quantization of Signals and Metrics in the Decoding of 8-PSK TCM

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    The performance of rate 2/3 8-PSK Trellis Coded Modulation was investigated as a function of the numerical resolution of the metrics and signal vectors used in decoding by the Viterbi algorithm. It was found that a 16 state Ungerboeck code using 5 bit I and Q with 7 bit metrics achieved roughly the same performance as pragmatic TCM. The findings were applied to the digital logic design of a TCM decoder

    Status epilepticus on the paediatric intensive care unit—the role of EEG monitoring

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    AbstractA pilot study was undertaken of the feasibility of continuous EEG monitoring of patients admitted to a Paediatric Intensive Care Unit (PICU) for management of status epilepticus or its immediate sequelae. Eight children were studied and seizure activity was recorded in four patients. Additional information influencing management was obtained: the bedside nurse considered decerebrate posturing in one patient to be a seizure: there were no epileptiform EEG changes. Another patient was considered to have seizures (clonic movements of both upper limbs) following cardiac arrest; the EEG showed electrocerebral silence, and thiopentone treatment was discontinued. In another patient, continuing epileptiform activity on EEG gave intensivists the confidence to use higher than usual doses of thiopentone. The problems encountered were delays in monitoring, once for a CT scan and once because of two admissions within hours of each other. We conclude that EEG monitoring on a PICU is feasible and provides clinically useful information

    Pragmatic Trellis Coded Modulation: A Simulation Using 24-Sector Quantized 8-PSK

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    Trellis Coded Modulation (TCM)[2,3,4], combines convolutional encoding with PSK or QAM signalling to provide spectrally efficient communication with forward error correction. Pragmatic TCM[1], uses the industry standard, 64-state, binary convolutional code. This paper presents a simulation of a pragmatic TCM system for 8-PSK. This system associates each sector of a quantized phase receiver[9] with a pair of weights to be used as soft decision inputs of the Viterbi decoder. This system approaches 3dB of coding gain at bit error rates of 10-5 and less

    On the Performance of Trellis Coded Modulation in a Concatenated Reed-Bolomon System

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    Concatenated systems combining the error correcting power of trellis codes and Reed-Solomon (RS) codes have been used to achieve error rates between 10-10 and 10-20 on satelite communications links [l]. The need for spectral efficiency has motivated consideration of of non-binary signalling with Ungerboeck [2,3] codes or the Pragmatic standard recently proposed by Viterbi [4], in place of quaternary signalling with rate 1/2 coding. In this paper we investigates the use of 8-PSK trellis-coded modulation (TCM) in a concatenated system using a (255,233) RS code. The use of the 8-PSK codes doubles the spectral efficiency with a performance cost of approximately 2 dB

    Assessing Hurricane Katrina Vegetation Damage at Stennis Space Center using IKONOS Image Classification Techniques

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    Hurricane Katrina hit southwestern Mississippi on August 29, 2005, at 9:45 a.m. CDT as a category 3 storm with surges up to approx. 9 m and sustained winds of approx. 120 mph. The hurricane's wind, rain, and flooding devastated several coastal towns, from New Orleans through Mobile. The storm also caused significant damage to infrastructure and vegetation of NASA's SSC (Stennis Space Center). Storm recovery at SSC involved not only repairs of critical infrastructure but also forest damage mitigation (via timber harvests and control burns to reduce fire risk). This presentation discusses an effort to use commercially available high spatial resolution multispectral IKONOS data for vegetation damage assessment, based on data collected over SSC on September 2, 2005

    Stochastic Real-time Optimal Control for Bearing-only Trajectory Planning

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    A method is presented to simultaneously solve the optimal control problem and the optimal estimation problem for a bearing-only sensor. For bearing-only systems that require a minimum level of certainty in position relative to a source for mission accomplishment, some amount of maneuver is required to measure range. Traditional methods of trajectory optimization and optimal estimation minimize an information metric. This paper proposes constraining the final value of the information states with known time propagation dynamics relative to a given trajectory which allows for attainment of the required level of information with minimal deviation from a general performance index that can be tailored to a specific vehicle. The proposed method does not suffer from compression of the information metric into a scalar, and provides a route that will attain a particular target estimate quality while maneuvering to a desired relative point or set. An algorithm is created to apply the method in real-time, iteratively estimating target position with an Unscented Kalman Filter and updating the trajectory with an efficient pseudospectral method. Methods and tools required for hardware implementation are presented that apply to any real-time optimal control (RTOC) system. The algorithm is validated with both simulation and flight test, autonomously landing a quadrotor on a wire

    An Allometric Analysis of Ontogenetic Changes (Variation) in the Cranial Morphology of Larvae of Hydaticus bimarginatus (Say) (Coleoptera: Dytiscidae: Dytiscinae)

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    Distortion coordinates (Cartesian transformations) are used to compare the ontogenetic allometry in cranial morphology of first, second, and third instars of Hydaticus bimarginatus (Say). The most significant difference in the dorsoventral view is the expansion of the posterior lateral margins. Cranial expansion is likely due to an increase in the mass of the adductor muscles which are responsible for closing the mandibles. The ontogenetic shift in head orientation to a more subprognathic position evident in the analysis of lateral silhouettes indicates that second and third instars may be adapted to feeding on substrate associated prey. These differences are thought to reflect possible changes in prey regimes and habitat preference occurring during larval development

    Pricing Derivatives the Martingale Way.

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    In recent years results from the theory of martingales has been successfully applied to problems in financial economics. In the present paper we show how efficient and elegant this "martingale technology" can be when solving for complex options. In particular we provide closed form solutions for several new classes of exotic options including the cliquet, the ladder, the discrete shout and the discrete lookback. We also provide a derivation of the price of an option on the maximum of n assets to demonstrate the power of the multi-dimensional Girsanov theorem. Although some of the results presented are well known, the treatment of the material in this paper is new in that it focuses on the application of the martingale technology to concrete problems in option pricing, methods that until now have mostly been used for purely theoretical purposes.

    Interacting Frobenius Algebras are Hopf

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    Theories featuring the interaction between a Frobenius algebra and a Hopf algebra have recently appeared in several areas in computer science: concurrent programming, control theory, and quantum computing, among others. Bonchi, Sobocinski, and Zanasi (2014) have shown that, given a suitable distributive law, a pair of Hopf algebras forms two Frobenius algebras. Here we take the opposite approach, and show that interacting Frobenius algebras form Hopf algebras. We generalise (BSZ 2014) by including non-trivial dynamics of the underlying object---the so-called phase group---and investigate the effects of finite dimensionality of the underlying model. We recover the system of Bonchi et al as a subtheory in the prime power dimensional case, but the more general theory does not arise from a distributive law.Comment: 32 pages; submitte
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