In this paper, we present simulation results for the bit error rate (BER) performance and the fading penalty of a BPSK subcarrier intensity modulation (BPSK-SIM) free-space optical (FSO) communication link in a log-no...
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ISBN:
(纸本)9781424449637
In this paper, we present simulation results for the bit error rate (BER) performance and the fading penalty of a BPSK subcarrier intensity modulation (BPSK-SIM) free-space optical (FSO) communication link in a log-normal atmospheric turbulence model. The results obtained are based on the Monte-Carlo simulation. Multiple subcarrier modulation schemes offer increased system throughput and require no knowledge of the channel fading in deciding what symbol has been received. In an atmospheric channel with a fading strength σ l 2 of 0.1 obtaining a BER of 10 -6 using a 2-subcarrier system will require a signal-tonoise (SNR) of 23.1 dB. The required SNR increases with the fading strength and at a BER of 10 -9 the fading penalty due to the atmospheric turbulence is ~ 41 dB for σ l 2 = 0.9. The comparative studies of the OOK and BPSK-SIM schemes showed that for similar electrical SNR, BPSK-SIM offered improved performance across all range of turbulence variance.
Background: It has been apparent in the last few years that small non coding RNAs (ncRNA) play a very significant role in biological regulation. Among these microRNAs (miRNAs), 22-23 nucleotide small regulatory RNAs, ...
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Background: It has been apparent in the last few years that small non coding RNAs (ncRNA) play a very significant role in biological regulation. Among these microRNAs (miRNAs), 22-23 nucleotide small regulatory RNAs, have been a major object of study as these have been found to be involved in some basic biological processes. So far about 706 miRNAs have been identified in humans alone. However, it is expected that there may be many more miRNAs encoded in the human genome. In this report, a "context-sensitive" Hidden Markov Model (CSHMM) to represent miRNA structures has been proposed and tested extensively. We also demonstrate how this model can be used in conjunction with filters as an ab initio method for miRNA identification. Results: The probabilities of the CSHMM model were estimated using known human miRNA sequences. A classifier for miRNAs based on the likelihood score of this "trained" CSHMM was evaluated by: (a) cross-validation estimates using known human sequences, (b) predictions on a dataset of known miRNAs, and (c) prediction on a dataset of non coding RNAs. The CSHMM is compared with two recently developed methods, miPred and CID-miRNA. The results suggest that the CSHMM performs better than these methods. In addition, the CSHMM was used in a pipeline that includes filters that check for the presence of EST matches and the presence of Drosha cutting sites. This pipeline was used to scan and identify potential miRNAs from the human chromosome 19. It was also used to identify novel miRNAs from small RNA sequences of human normal leukocytes obtained by the Deep sequencing (Solexa) methodology. A total of 49 and 308 novel miRNAs were predicted from chromosome 19 and from the small RNA sequences respectively Conclusion: The results suggest that the CSHMM is likely to be a useful tool for miRNA discovery either for analysis of individual sequences or for genome scan. Our pipeline, consisting of a CSHMM and filters to reduce false positives shows promise as
Reducing packet latency is an important requirement in embedded networks. Source routing can be used to reduce processing delay at intermediate nodes and thereby reduce the overall packet latency. However source routi...
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Due to the geographical distribution, different cognitive capacity, and different domain competency of workers or learners, many misunderstandings can occur during Web based remote collaboration, leading to inefficien...
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Different learners have different needs;they differ, for example, in their learning goals, their prior knowledge, their learning styles, and their cognitive abilities. Adaptive web-based educational systems aim to cat...
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In this paper, we propose a novel method to measure the distance between two Gaussian Mixture Models. The proposed distance measure is based on the minimum cost that must paid to transform from one Gaussian Mixture Mo...
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ISBN:
(纸本)9781605588407
In this paper, we propose a novel method to measure the distance between two Gaussian Mixture Models. The proposed distance measure is based on the minimum cost that must paid to transform from one Gaussian Mixture Model into the other. We parameterize the components of a Gaussian Mixture Model which are Gaussian probability density functions (pdf) as positive definite lower triangular transformation matrices. Then we identify that Gaussian pdfs form a Lie group. Based on Lie group theory, the geodesic length can be used to measure the minimum cost that must paid to transform from one Gaussian pdf into the other. Combining geodesic length with the earth mover's distance, we propose the Lie group earth mover's distance for Gaussian Mixture Models. We test our distance measure in image retrieval. The experimental results indicate that our distance measure is more effective than other measures including the Kullback-Liebler divergence. Copyright 2009 ACM.
In grid and cloud computing infrastructures, the integrity of a computing platform is a critical security requirement in order to provide secure and honest computing environments to service providers and resource cons...
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Security and privacy are widely held to be fundamental requirements for establishing trust in digital business. This paper examines the relationship between the factors, and the different strategies that may be needed...
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