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1
Formeister, Richard. "DIVERSITY BRANCH SELECTION IN REAL WORLD APPLICATION." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604498.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaMultipath propagation continues to be the dominant channel impairment in many aeronautical mobile telemetry (AMT) applications. Avoidance and diversity techniques continue to be the only practical means to combat this problem. In 2004 limited results from the development of a new post-detection, no-hit diversity selector were reported. Late breaking results from flight test were reported orally. A review of the methodology, flight test results and conclusions are presented in this paper. Also presented is an update describing enhancements of the implementation which emphasize operational flexibility as well as support for alternate demodulator products.
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Jefferis, Robert P. "TELEMETRY LINK RELIABILITY IMPROVEMENT VIA “NO-HIT” DIVERSITY BRANCH SELECTION." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605302.
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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaMultipath propagation consisting largely of specular reflection components is known to be the major channel impairment in many aeronautical mobile telemetry (AMT) applications. Adaptive equalizers are not effective against flat fading commonly created by strong power delay profile components representing small fractions of the transmitted symbol period. Avoidance and diversity techniques are the only practical means of combating this problem. A new post-detection, no-hit diversity branch selector is described in this paper. Laboratory and limited flight test data comparing non-diversity, selection diversity and intermediate frequency (IF) combining techniques are presented.
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Smith, Shaun. "Combining Markowitz's selection model with different investment styles." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/64816.
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Portfolio selection has been a well-researched topic since the mid 1950Õs. Researchers such as Harry Markowitz obtained the Noble Prize for his work on portfolio selection. His model, which is underpinned by the concept that the market is efficient, has been the cornerstone of many investment strategies over the years.
Recently, however, many authors have claimed that the markets are inefficient, and that one cannot rely on a model that assumes a linear and static relationship between risk and reward, making the Markowitz Portfolio Selection Model (MPSM) obsolete.
Literature suggests that much of this inefficiency is created through the use of different styles; that is, styles in which shares are grouped together based on certain fundamental characteristics, to inform the investment strategies of investors.
Therefore, this study endeavours to supplement the MPSM with different investment styles. Firstly, testing whether the risk adjustment afforded by the MPSM is positively influenced by the different investment styles. Secondly, to determine which style achieves the highest returns over the selected period.
Monthly total return data from the JSE was used and portfolio rebalancing took place every six months for a period of 10 years. The share weightings of the portfolios were informed by risk adjusted style based predicted returns. The performance of these portfolios was subsequently compared.
Results indicated that style influenced portfolios outperform the non-style influenced MPSM, with some styles providing greater returns than others over the period selected.Mini Dissertation (MBA)--University of Pretoria, 2017.
lt2018
Gordon Institute of Business Science (GIBS)
MBA
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Jensen, Richard. "Combining rough and fuzzy sets for feature selection." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/24740.
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Feature selection (FS) refers to the problem of selecting those input attributes that are most predictive of a given outcome; a problem encountered in many areas such as machine learning, pattern recognition and signal processing. Unlike other dimensionality reduction methods, feature selectors preserve the original meaning of the features after reduction. This has found application in tasks that involve datasets containing huge numbers of features (in the order of tens of thousands), which would be impossible to process further. Recent examples include text processing and web content classification. FS techniques have also been applied to small and medium-sized datasets in order to locate the most informative features for later use. Many feature selection methods have been developed and are reviewed critically in this thesis, with particular emphasis on their current limitations. The leading methods in this field are presented in a consistent algorithmic framework. One of the many successful applications of rough set theory has been to this area. The rough set ideology of using only the supplied data and no other information has many benefits in FS, where most other methods require supplementary knowledge. However, the main limitation of rough set-based feature selection in the literature is the restrictive requirement that all data is discrete. In classical rough set theory, it is not possible to consider real-valued or noisy data. This thesis proposes and develops an approach based on fuzzy-rough sets, fuzzy rough feature selection (FRFS), that addresses these problems and retains dataset semantics. Complexity analysis of the underlying algorithms is included. FRFS is applied to two domains where a feature reducing step is important; namely, web content classification and complex systems monitoring. The utility of this approach is demonstrated and is compared empirically with several dimensionality reducers. In the experimental studies, FRFS is shown to equal or improve classification accuracy when compared to the results from unreduced data. Classifiers that use a lower dimensional set of attributes which are retained by fuzzy-rough reduction outperform those that employ more attributes returned by the existing crisp rough reduction method. In addition, it is shown that FRFS is more powerful than the other FS techniques in the comparative study. Based on the new fuzzy-rough measure of feature significance^ further development of the FRFS technique is presented in this thesis. This is developed from the new area of feature grouping that considers the selection of groups of attributes in the search for the best subset. A novel framework is also given for the application of ant-based search mechanisms within feature selection in general, with particular emphasis on its employment in FRFS. Both of these developments are employed and evaluated within the complex systems monitoring application.
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JAIN, VISHESH. "PERFORMANCE ANALYSIS OF GENERALIZED SELECTION COMBINING IN ARBITRARILY CORRELATED NAKAGAMI FADING CHANNELS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1131175492.
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Zhu, Chao. "Performance Analysis of Minimum Selection GSC with Channel Estimation Errors in Rayleigh Fading Channels." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250184723.
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Suen, Martin L. "Syndrome selection diversity combining in an indoor mobile radio environment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0026/MQ31645.pdf.
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Romano, Eduardo O. "Selection indices for combining marker genetic data and animal model information /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192009-040546/.
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Romano, Eduardo. "Selection indices for combining marker genetic data and animal model information." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/44879.
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It was suggested that marker and phenotypic information be combined in order to obtain more accurate or earlier genetic evaluations. An improvement in accuracy or time of evaluation due to utilization of marker assisted selection (MAS) increases genetic progress. Fernando and Grossman (1989) suggested including marker information directly into the Animal Model, Best Linear Unbiased Prediction system, but several problems need to be solved before their approach becomes feasible. Other selection indices were suggested but either do not use all the available information or are suitable only for evaluation of the offspring of the sire from which the marker information was established.
A selection index combining marker and Animal Model information was developed to allow comparisons involving offspring, grandoffspring and great-grandoffspring of a sire. Marker information was assumed to be a least square estimate of the difference between the average effects of the two quantitative trait loci (QTL) alleles present in a sire (Dp) and the standard error of this estimate (SE(Dp)). Estimates may have been obtained from a daughter or granddaughter design. Comparisons among grandoffspring and great-grandoffspring also require an estimate of the recombination rate (r) between the marker and the QTL. The Animal Model information consists of predicted transmitting ability (PTA) and reliability of PTA. PTA was assumed not to include any marker information. The expected percentage of the gain in accuracy (PGA) due to the inclusion of marker information in the selection indices is affected by the degree of polymorphism at the marker locus. The polymorphism information content (PIC) of a marker locus was computed for the second and third generations and for mates genotyped or not. PGA increased with larger Dos lower SE(Dp), lower r, a smaller number of own and progeny records, and larger PIC. PGA and PIC reduce over generations. Marker information in dairy cattle is likely to be used in generations beyond offspring. Then, only the use of highly polymorphic markers with a large and accurately estimated effect may be economically justified.Master of Science
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Reid, Eric. "ENCRYPTED CORRELATING SOURCE SELECTOR." International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604265.
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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaModern telemetry and data streams are often encrypted. The majority of range testing activities require multiple ground stations to collect these streams and send them to a central processing location. Each of these streams currently needs to be individually decrypted before best source selection, processing and analysis. Using innovative techniques, it is possible to time correlate these encrypted streams, compare them with each other and create an output stream of better quality than any of the individual streams. This stream can then be decrypted by a single decryption device, greatly reducing cost and complexity.
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Kontodios, Pierros. "Performance analysis of noncoherent Binary Frequency Shift Keying using Equal Gain Combining and Post Detection Selection Combining over a Nakagami fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA354305.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 1998."September 1998." Thesis advisor(s): Tri T. Ha, Ralph D. Hippenstiel. Includes bibliographical references (p. 97). Also available online.
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Zhang, Yi. "Strategies for Combining Tree-Based Ensemble Models." NSUWorks, 2017. http://nsuworks.nova.edu/gscis_etd/1021.
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Ensemble models have proved effective in a variety of classification tasks. These models combine the predictions of several base models to achieve higher out-of-sample classification accuracy than the base models. Base models are typically trained using different subsets of training examples and input features. Ensemble classifiers are particularly effective when their constituent base models are diverse in terms of their prediction accuracy in different regions of the feature space. This dissertation investigated methods for combining ensemble models, treating them as base models. The goal is to develop a strategy for combining ensemble classifiers that results in higher classification accuracy than the constituent ensemble models. Three of the best performing tree-based ensemble methods – random forest, extremely randomized tree, and eXtreme gradient boosting model – were used to generate a set of base models. Outputs from classifiers generated by these methods were then combined to create an ensemble classifier. This dissertation systematically investigated methods for (1) selecting a set of diverse base models, and (2) combining the selected base models. The methods were evaluated using public domain data sets which have been extensively used for benchmarking classification models. The research established that applying random forest as the final ensemble method to integrate selected base models and factor scores of multiple correspondence analysis turned out to be the best ensemble approach.
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Green, Michael C. "An Efficient Primer Selection Process Combining Progressive and Iterative Multiple Sequence Alignment Strategies: ClustalW and HMMER." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/547.
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This thesis describes a method for using a computationally efficient algorithm to identify candidate DNA primer sequences. DNA sequencing primers are a critical element of polymerase chain reaction (PCR) and DNA sequence analysis. A variety of methods for deriving DNA primers exist, but such methods are often computationally intensive, or do not use available sequence data that could potentially serve as a possible resource for primer identification. Though no current algorithm exists which will always yield a correct primer for every need, evaluation of multi-sequence alignments may provide a reliable source for primer candidates. However, an exact mathematical solution for multi-sequence alignments, using currently available computational resources, is only viable for a very small number of sequences. Any solution for a larger number of sequences will therefore use other computational methods and heuristics to estimate an alignment.
The solution presented here, featuring a combination of ClustalW and HMMER alignment tools, is able to identify conserved regions in sequence data in a computationally efficient manner, and from these regions, suggest viable primer candidates. Computational complexity for the HMMER alignment effort has been maintained at O(MN); the suggested process for creating sequence alignments lead to a 15-fold improvement in performance over conventional methods, while also successfully identifying fungal specific primers, with individual examples showing 90% or greater match for the given fungal phylum.
It was found that alignment quality could be further improved by using simple sorting methods against input sequence data.
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Conka, Tahir. "Performance analysis of noncoherent differential phase shift keying using Post-Detection Selection Combining over a Rayleigh fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA346398.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1998.Thesis advisor(s): Tri T. Ha, Ralph D. Hippenstiel. "June 1998." Includes bibliographical references (p. 77). Also available online.
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ISLAM, MD JAHERUL. "Performance Analysis of Diversity Techniques for Wireless Communication System." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1962.
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Different diversity techniques such as Maximal-Ratio Combining (MRC), Equal-Gain Combining (EGC) and Selection Combining (SC) are described and analyzed. Two branches (N=2) diversity systems that are used for pre-detection combining have been investigated and computed. The statistics of carrier to noise ratio (CNR) and carrier to interference ratio (CIR) without diversity assuming Rayleigh fading model have been examined and then measured for diversity systems. The probability of error (p_e) vs CNR and (p_e) versus CIR have also been obtained. The fading dynamic range of the instantaneous CNR and CIR is reduced remarkably when diversity systems are used [1]. For a certain average probability of error, a higher valued average CNR and CIR is in need for non-diversity systems [1]. But a smaller valued of CNR and CIR are compared to diversity systems. The overall conclusion is that maximal-ratio combining (MRC) achieves the best performance improvement compared to other combining methods. Diversity techniques are very useful to improve the performance of high speed wireless channel to transmit data and information. The problems which considered in this thesis are not new but I have tried to organize, prove and analyze in new ways.
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Polychronos, Theofanis. "Performance analysis of Binary FSK signals with L-Fold diversity selection combining techniques in a Nakagami-M fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA353062.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 1998."September 1998." Thesis advisor(s): Tri T. Ha, Ralph D. Hippenstiel. Includes bibliographical references (p. 61). Also available online.
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Silva, Glauco Barbosa da. "Combining data mining techniques with multicriteria decision aid in classification problems with composition probabilistc of preferences in trichotomic procedure (CPP-TRI)." Niterói, 2017. https://app.uff.br/riuff/handle/1/4079.
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Problem: From Modeling decision maker preferences, the Multicriteria Decision Aid (MCDA) is a field dedicated to the study of real-world decision-making problems that are, usually, too complex and not so well-structured to be considered through the examination of a single point of view (criteria). This feature of MCDA implies that a comprehensive model of a decision maker situation cannot be “created”, but instead, the model should be developed to meet the requirements of the Decision Maker (DM). In general, the development of such a model can only be achieved through an iterative and interactive process, until the preferences of the decision maker are consistently represented in the model. However, an interactive method is a procedure that consists of an alternation of calculation and discussion stages, which presumes that the decision maker is willing to answer a large number of relatively difficult questions. For instance, one of the main difficulties to be faced when interacting with a Decision Maker in order to build a decision aid procedure is the various parameters’ elicitation of the preference model. Methodology: In this thesis, as an alternative to interactive process, among the main streams of MCDA, a Preference Disaggregation Analysis method was used, which is considered to assess or to infer preference models from the given preferential structures and to address decision-aiding activities to elicit preferential information and to construct decision models from decision examples. Combining Composition Probabilistic of Preference with Data Mining techniques, a proposal of a three-step process is presented: attribute selection; clustering; and classification. The first and the second ones are data mining tasks and the last one is a multicriteria task. Purpose: This thesis aims to present a new approach with a Data Mining Layer (attribute selection and/or clustering) in Composition Probabilistic of Preferences in Trichotomic procedure (CPP-TRI), which combines data mining techniques with a Multicriteria Decision Aid method in classification (sorting) problems. Findings: The decision maker ability to comprehend without powerful tools has been exceeded. Therefore, important decisions are often made based not on the information-rich data stored in data repositories, but rather, on intuition of the decision maker. Involved in similar problems, the connections between disaggregation methods and data mining (identifying patterns, extracting knowledge from data, eliciting preferential information and constructing decision models from decision examples) are explored to combine and improve the CPP-TRI Method from Attribute Selection Techniques.
Problem: From Modeling decision maker preferences, the Multicriteria Decision Aid (MCDA) is a field dedicated to the study of real-world decision-making problems that are, usually, too complex and not so well-structured to be considered through the examination of a single point of view (criteria). This feature of MCDA implies that a comprehensive model of a decision maker situation cannot be “created”, but instead, the model should be developed to meet the requirements of the Decision Maker (DM). In general, the development of such a model can only be achieved through an iterative and interactive process, until the preferences of the decision maker are consistently represented in the model. However, an interactive method is a procedure that consists of an alternation of calculation and discussion stages, which presumes that the decision maker is willing to answer a large number of relatively difficult questions. For instance, one of the main difficulties to be faced when interacting with a Decision Maker in order to build a decision aid procedure is the various parameters’ elicitation of the preference model. Methodology: In this thesis, as an alternative to interactive process, among the main streams of MCDA, a Preference Disaggregation Analysis method was used, which is considered to assess or to infer preference models from the given preferential structures and to address decision-aiding activities to elicit preferential information and to construct decision models from decision examples. Combining Composition Probabilistic of Preference with Data Mining techniques, a proposal of a three-step process is presented: attribute selection; clustering; and classification. The first and the second ones are data mining tasks and the last one is a multicriteria task. Purpose: This thesis aims to present a new approach with a Data Mining Layer (attribute selection and/or clustering) in Composition Probabilistic of Preferences in Trichotomic procedure (CPP-TRI), which combines data mining techniques with a Multicriteria Decision Aid method in classification (sorting) problems. Findings: The decision maker ability to comprehend without powerful tools has been exceeded. Therefore, important decisions are often made based not on the information-rich data stored in data repositories, but rather, on intuition of the decision maker. Involved in similar problems, the connections between disaggregation methods and data mining (identifying patterns, extracting knowledge from data, eliciting preferential information and constructing decision models from decision examples) are explored to combine and improve the CPP-TRI Method from Attribute Selection Techniques.
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Hill, Terry. "Metrics and Test Procedures for Data Quality Estimation in the Aeronautical Telemetry Channel." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596445.
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ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVThere is great potential in using Best Source Selectors (BSS) to improve link availability in aeronautical telemetry applications. While the general notion that diverse data sources can be used to construct a consolidated stream of "better" data is well founded, there is no standardized means of determining the quality of the data streams being merged together. Absent this uniform quality data, the BSS has no analytically sound way of knowing which streams are better, or best. This problem is further exacerbated when one imagines that multiple vendors are developing data quality estimation schemes, with no standard definition of how to measure data quality. In this paper, we present measured performance for a specific Data Quality Metric (DQM) implementation, demonstrating that the signals present in the demodulator can be used to quickly and accurately measure the data quality, and we propose test methods for calibrating DQM over a wide variety of channel impairments. We also propose an efficient means of encapsulating this DQM information with the data, to simplify processing by the BSS. This work leads toward a potential standardization that would allow data quality estimators and best source selectors from multiple vendors to interoperate.
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Chi, Zhanjiang. "Performance Analysis of Maximal-Ratio Combining and Space-Time Block Codes with Transmit Antenna Selection over Nakagami-m Fading Channels." School of Electrical and Information Engineering, 2007. http://hdl.handle.net/2123/2012.
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Master of Engineering (Research)The latest wireless communication techniques such as highspeed wireless internet application demand higher data rates and better quality of service (QoS). However, transmission reliability is still degraded by harsh propagation channels. Multiple-input multiple-output (MIMO) systems can increase the system capacity and improve transmission reliability. By transmitting multiple copies of data, a MIMO system can effectively combat the effects of fading. Due to the high hardware cost of a MIMO system, antenna selection techniques have been applied in MIMO system design to reduce the system complexity and cost. The Nakagami-m distribution has been considered for MIMO channel modeling since a wide range of fading channels, from severe to moderate, can be modeled by using Nakagami-m distribution. The Rayleigh distribution is a special case of the Nakagami-m distribution. In this thesis, we analyze the error performance of two MIMO schemes: maximal-ratio combining with transmit antenna selection (the TAS/MRC scheme) and space-time block codes with transmit antenna selection (the TAS/STBC scheme) over Nakagami-m fading channels. In the TAS/MRC scheme, one of multiple transmit antennas, which maximizes the total received signal-to-noise ratio (SNR), is selected for uncoded data transmission. First we use a moment generating function based (MGF-based) approach to derive the bit error rate (BER) expressions for binary phase shift keying (BPSK), the symbol error rate (SER) expressions for M-ray phase shift keying (MPSK) and M-ray quadrature amplitude modulation (MQAM) of the TAS/MRC scheme over Nakagami-m fading channels with arbitrary and integer fading parameters m. The asymptotic performance is also investigated. It is revealed that the asymptotic diversity order is equal to the product of the Nakagami fading parameter m, the number of transmit antenna Lt and the number of receive antenna Lr as if all transmit antenna were used. Then a Gaussian Q-functions approach is used to investigate the error performance of the TAS/STBC scheme over Nakagami-m fading channels. In the TAS/STBC scheme, two transmit antennas, which maximize the output SNR, are selected for transmission. The exact and asymptotic BER expressions for BPSK are obtained for the TAS/STBC schemes with three and four transmit antennas. It is shown that the TAS/STBC scheme can provide a full diversity order of mLtLr.
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Deora, Gautam Krishnakumar. "Simulation and Mathematical Tools for Performance Analysis of Low-Complexity Receivers." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31127.
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In recent years, research on the design and performance evaluation of suboptimal receiver implementations has received considerable attention owing to complexity in the realization of the optimal receiver algorithms over wireless channels. This thesis addresses the effects of using reduced complexity receivers for the Satellite Digital Audio Radio (SDAR), Code Division Multiple Access (CDMA) and UltraWideband (UWB) communications technologies.
A graphical-user-interface simulation tool has been developed to predict the link reliability performance of the SDAR services in the continental United States. Feasibility study of receiving both satellite and terrestrial repeater signals using a selection diversity (single antenna) receiver has also been performed.
The thesis also develops a general mathematical framework for studying the efficacy of a sub-optimal generalized selection combining (GSC) diversity receiver over generalized fading channel models. The GSC receiver adaptively combines a subset of M diversity paths with the highest instantaneous signal-to-noise ratios (SNR) out of the total L available diversity paths. The analytical framework is applicable for rake receiver designs in CDMA and UWB communications.Master of Science
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Haider, Iqbal Hasan, and MD Fazla Rabby. "Performance Analysis of Cognitive Radio Network over SIMO System." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3439.
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As resources are limited, radio spectrum becomes congested due to the growth of wireless applications. However, measurements address the fact that most of the licensed spectrums experience low utilization even in intensively teeming areas. In the exertion to improve the utilization of the limited spectrum resources, cognitive radio networks have emerged as a powerful technique to resolve this problem. There are two types of user in cognitive radio networks (CRNs) named as primary user (PU) and secondary user (SU). Therein, the CRN enables the SU to utilize the unused licensed frequency of the PU if it possibly finds the vacant spectrum or white space (known as opportunistic spectrum access). Alternatively, SU can transmit simultaneously with the PU provided that transmission power of SU does not cause any harmful interference to the PU (known as spectrum sharing systems). In this thesis work, we study fundamental knowledge of the CRNs and focus on the performance analysis of the single input multiple output (SIMO) system for spectrum sharing approach. We assume that a secondary transmitter (SU-Tx) has full channel state information (CSI). The SU-Tx can adjust its transmit power not to cause harmful interference to the PU and obtain an optimal transmit rate. In particular, we derive the closed-form expressions for the cumulative distribution function (CDF), outage probability and an analytical expression for symbol error probability (SEP).As resources are limited, radio spectrum becomes congested due to the growth of wireless applications. However, measurements address the fact that most of the licensed spectrums experience low utilization even in intensively teeming areas. In the exertion to improve the utilization of the limited spectrum resources, cognitive radio networks have emerged as a powerful technique to resolve this problem. There are two types of user in cognitive radio networks (CRNs) named as primary user (PU) and secondary user (SU). Therein, the CRN enables the SU to utilize the unused licensed frequency of the PU if it possibly finds the vacant spectrum or white space (known as opportunistic spectrum access). Alternatively, SU can transmit simultaneously with the PU provided that transmission power of SU does not cause any harmful interference to the PU (known as spectrum sharing systems). In this thesis work, we study fundamental knowledge of the CRNs and focus on the performance analysis of the single input multiple output (SIMO) system for spectrum sharing approach. We assume that a secondary transmitter (SU-Tx) has full channel state information (CSI). The SU-Tx can adjust its transmit power not to cause harmful interference to the PU and obtain an optimal transmit rate. In particular, we derive the closed-form expressions for the cumulative distribution function (CDF), outage probability and an analytical expression for symbol error probability (SEP).
Iqbal Hasan Haider, cell: +46704571807 MD. Fazla Rabby, cell: +46734965477
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Aldosari, Mansour. "Design and analysis of green mobile communication networks." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/design-and-analysis-of-green-mobile-communication-networks(37b5278a-45da-4a81-b89c-54c7d876586a).html.
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Increasing energy consumption is a result of the rapid growth in cellular communication technologies and a massive increase in the number of mobile terminals (MTs) and communication sites. In cellular communication networks, energy efficiency (EE) and spectral efficiency (SE) are two of the most important criteria employed to evaluate the performance of networks. A compromise between these two conflicting criteria is therefore required, in order to achieve the best cellular network performance. Fractional frequency reuse (FFR), classed as either strict FFR or soft frequency reuse (SFR), is an intercell interference coordination (ICIC) technique applied to manage interference when more spectrum is used, and to enhance the EE. A conventional cellular model's downlink is designed as a reference in the presence of inter-cell interference (ICI) and a general fading environment. Energy-efficient cellular models,such as cell zooming, cooperative BSs and relaying models are designed, analysed and compared with the reference model, in order to reduce network energy consumption without degrading the SE. New mathematical models are derived herein to design a distributed antenna system (DAS), in order to enhance the system's EE and SE. DAS is designed in the presence of ICI and composite fading and shadowing with FFR. A coordinate multi-point (CoMP) technique is applied, using maximum ratio transmission (MRT) to serve the mobile terminal (MT), with all distributed antenna elements (DAEs), transmit antenna selection (TAS) being applied to select the best DAE and general selection combining (GSC) being applied to select more than one DAE. Furthermore, a Cloud radio access network (C-RAN) is designed and analysed with two different schemes, using the high-power node (HPN) and a remote radio head (RRH), in order to improve the EE and SE of the system. Finally, a trade-off between the two conflicting criteria, EE and SE, is handled carefully in this thesis, in order to ensure a green cellular communication network.
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Terres, Laerte Reis. "Escolha de genitores e estratégias de seleção para caracteres de aparência de tubérculo, rendimento e qualidade de fritura, em batata." Universidade Federal de Pelotas, 2014. http://repositorio.ufpel.edu.br:8080/handle/prefix/3059.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Em programas de melhoramento genético de batata, a escolha de genitores e de estratégias de seleção devem ser definidos, cuidadosamente, e incorporados, como prática nos programas, para aumentar a eficiência e a eficácia. A pesquisa foi composta de cinco estudos. O primeiro teve como objetivo verificar as estimativas de capacidades de combinação de genitores de batata em gerações iniciais de seleção. Foram avaliadas 12 famílias segregantes, entre dois grupos de genitores de batata em um dialelo parcial (4x3). As famílias foram avaliadas para caracteres de aparência e rendimento de tubérculos. Os dados foram submetidos às analises de variância e dialélica parcial. Verificou-se que há predominância de efeitos aditivos dos genes para os caracteres uniformidade de formato, apontamento, curvatura, aparência geral, uniformidade de tamanho, número, massa e massa média de tubérculos. O segundo estudo teve como objetivo de estimar as respostas esperadas de seleção para caracteres de rendimento, de aparência e qualidade de fritura. Foram estudadas três populações segregantes de batata para caracteres de rendimento, aparência de tubérculos e qualidade de fritura. Os dados foram analisados estatisticamente segundo o modelo REML/BLUP. As respostas esperadas de seleção para qualidade de fritura sugerem que para se obter populações superiores deve-se utilizar ao menos um genitor de ótima qualidade de fritura. O terceiro estudo teve como objetivo principal estimar os parâmetros genéticos de caracteres componentes de rendimento e aparência de tubérculo nas primeiras gerações de seleção. Foram avaliadas 12 famílias segregantes de batata para caracteres de rendimento e aparência de tubérculos. Pode-se concluir que seleção pode ser aplicada com intensidade de leve a moderada na geração de plântula para os caracteres textura de película, aparência geral, número, massa e massa média de tubérculos. O quarto estudo objetivou verificar correlações entre e dentro de gerações para caracteres de aparência e rendimento de tubérculos, nas gerações iniciais de seleção e as implicações destas correlações na seleção. Foram VII avaliadas 12 famílias segregantes de batata nas gerações de plântula e primeira geração de campo, para caracteres de rendimento e aparência de tubérculo. Foram realizadas análises de correlação entre e dentro das gerações. Os resultados demonstraram que seleção de forma negativa pode ser aplicada na geração de plântula para apontamento, número e massa média de tubérculos, descartando os extremos. Ainda sugerem que a seleção para massa de tubérculos pode ser feita selecionando com leve intensidade para os caracteres tamanho e massa média. O quinto estudo teve como objetivo comparar a eficiência de diferentes índices de seleção de clones superiores de batata. Foram comparados seis índices de seleção. Foram estudadas três populações híbridas de batata, para caracteres de rendimento e aparência de tubérculos. O índice multiplicativo e o índice de “ranks” mostraram-se mais eficientes.
In potato breeding programs, the choice of parents and selection of strategies must be carefully defined, and incorporated as a practice in programs trying to increase the efficiency and efficacy. The research consisted of five studies. The first study aimed to verify the combining ability of potato parents in early generations of selection. Twelve segregating potato families derived from crosses between two groups of parents in a partial diallel (3x4) were evaluated. The families were evaluated to tuber appearance and yield traits. Data were analyzed for variance and partial diallel analysis. It was found that there is predominance of additive effects of genes for skin color, tuber shape uniformity, tuber pointing, tuber curvature, general tuber appearance, tuber size uniformity, tuber number, tuber yield, and average tuber weight. The second study aimed to estimate the expected response to selection for yield, appearance and fry quality traits. Three hybrid potato populations were studied and evaluated to yield, appearance and fry quality. Data were statistically analyzed according to the REML/BLUP model. The expected response to selection for frying quality suggests that to obtain superior populations, at least one parent of good fry quality should be used. The third study aimed to estimate genetic parameters for yield and tuber appearance traits in early generations of selection. Twelve segregating potato families were evaluated to yield and appearance traits. The experimental design was randomized blocks. It was concluded that selection can be applied with mild to moderate intensity in seedling generating for skin texture, general tuber appearance, tuber number, tuber yield, and average tuber yield. The fourth study aimed to examine correlations between and within generations for tuber appearance and tuber yield in early generations of selection and their implications in the selection. Twelve segregating potato families were evaluated in seedling and first field generation to appearance and yield traits. Correlation analysis between and within generations were performed. The results showed that negative selection can be applied in the seedling generation for tuber IX pointing, tuber number, and average tuber weight. The results also suggest that selection for tuber yield can be applied at mild intensity for average tuber weight and tuber size. The fifth study aimed to compare the efficiency of different index selection methods for selection of superior potato clones. Three hybrid potato populations were studied. Six selection index were compared. The families were evaluated to yield and appearance traits. It was concluded that the multiplicative index and the index based on the sum of ranks are more efficient.
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Farias, Eder Jacques Porfirio. "AnÃlise de Sistemas OFDM Cooperativos AF com Amplificadores de PotÃncia NÃo Linearesâ." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10366.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorCooperation diversity and orthogonal frequency division multiplexing (OFDM) are two key technologies for the modern wireless communication systems. The cooperative communication systems considered through this work use the OFDM technology and they are composed of: one transmitter with a nonlinear power amplifier (PA), one or more amplify-and-forward (AF) relays, also having a nonlinear PAs, and one destination node. In this dissertaion, it is initially proposed an optimal receiver, in the signal to noise ratio (SNR) sense, for a nonlinear cooperative AF system. The proposed receiver uses the maximum ratio combining (MRC) diversity technique to combine the received signas, assuming that both the source-destination and source-relay-destination links are available. In the sequel, closed-form expressions for the instantaneous SNR and outage probability of the considered system are developed. The outage analysis is then extended to the case of a multi-hop system, that is, with multiple serial relays. Finally, an outage analysis is also proposed for a nonlinear AF OFDM system using a Selection Combining receiver, considering two cases: one relay and multiple parallel relays. Numerical simulation results are presented through the work, evaluating the performance of the proposed receiver and theoretical expressions.
A diversidade cooperativa e a multiplexaÃÃo por divisÃo de frequÃncias ortogonais (Orthogonal Frequency Division Multiplexing - OFDM) sÃo duas das principais tecnologias para os sistemas de comunicaÃÃo sem fio modernos. Os sistemas de comunicaÃÃo cooperativos considerados neste trabalho de dissertaÃÃo utilizam a tecnologia OFDM e possuem: uma fonte com amplificador de potÃncia nÃo linear, um ou mais repetidores (relays) do tipo amplifica-e-encaminha (Amplify-and-Forward - AF), tambÃm com amplificadores de potÃncia (Power Amplifier - PA) nÃo lineares, e um nà destino. PropÃe-se inicialmente um receptor Ãtimo, no sentido da razÃo sinal ruÃdo (Signal-to-Noise Ratio - SNR) para um sistema OFDM cooperativo nÃo linear. Usando a tÃcnica de diversidade por combinaÃÃo de razÃo mÃxima (Maximal Ratio Combining - MRC) para tratar os sinais recebidos, o receptor proposto considera tanto as informaÃÃes oriundas do caminho direto (fonte-destino) como as provenientes do repetidor. Posteriormente, sÃo apresentadas expressÃes para o cÃlculo da SNR instantÃnea e da probabilidade de outage do sistema proposto. Fez-se ainda, uma proposta de expressÃo para o cÃlculo da probabilidade de outage do sistema considerando mÃltiplos relays em sÃrie. Por fim, propÃe-se expressÃes para o cÃlculo da probabilidade de outage do sistema utilizando receptor Selection Combining para um e para mÃltiplos relays dispostos paralelamente. Resultados de simulaÃÃo sÃo apresentados durante todo o trabalho, evidenciando o desempenho do receptor e das expressÃes propostas.
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Cerovic, Stefan. "Cooperative wireless communications in the presence of limited feedback." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC079/document.
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Dans cette thèse, les techniques de coopération ont été étudiées pour un canal multi-accès multi-relais composé d'au moins deux sources qui communiquent avec une seule destination à l'aide d'au moins deux nœuds de relayage en mode semi-duplex. Le multiplexage par répartition dans le temps est supposé. Tout d'abord, l’algorithme d’adaptation de lien est exécuté par l'ordonnanceur centralisé. Durant la première phase de transmission, les sources transmettent chacune à leur tour leur message respectif pendant des intervalles de temps consécutifs. Dans chaque intervalle de temps dans la deuxième phase, la destination planifie un nœud pour transmettre les redondances, mettant en œuvre un protocole coopératif d'Hybrid Automatic Repeat reQuest (HARQ), où les canaux de contrôle limités bidirectionnels sont disponibles depuis les sources et les relais vers la destination. Dans la première partie de la thèse, les stratégies de sélection des nœuds centralisé sont proposées pour la deuxième phase de transmission. Les décisions d’ordonnancement sont prises en fonction de la connaissance des ensembles de sources correctement décodées par chaque noeud et ayant comme objectif de maximiser l’efficacité spectrale moyenne. L'analyse de la probabilité de coupure de l'information ainsi que les simulations Monte-Carlo (MC) sont effectués afin de valider ces stratégies. Dans la seconde partie, un algorithme d’adaptation de lien lent est proposé afin de maximiser l’efficacité spectrale moyenne sous contrainte de vérification d'une qualité de service individuelle cible pour une famille donnée de schémas de modulation et de codage, réposant sur l'information sur la distribution des canaux signalée. Les débits des sources discrets sont déterminés en utilisant l’approche "Genie-Aided" suivie d’un algorithme itératif de correction de débit. Les simulations MC montrent que l’algorithme d’adaptation de lien proposé offre des performances proches de celles de la recherche exhaustive. Dans la troisième partie, les performances de protocole HARQ à redondance incrémentale (IR) avec codage mono et multi-utilisateur, ainsi que l'HARQ de type Chase Combining avec codage mono-utilisateur sont comparées. Les simulations MC montrent que l'IR-HARQ avec codage mono-utilisateur offre le meilleur compromis entre performance et complexité pour le scénario de petit nombre de sources. Un schéma de codage pratique est proposé et validé à l'aide de simulations MCIn this thesis, cooperation techniques have been studied for Multiple Access Multiple Relay Channel, consisted of at least two sources which communicate with a single destination with the help of at least two half-duplex relaying nodes. Time Division Multiplexing is assumed. First, the link adaptation algorithm is performed at the centralised scheduler. Sources transmit in turns in consecutive time slots during the first transmission phase. In each time slot of the second phase, the destination schedules a node to transmit redundancies, implementing a cooperative Hybrid Automatic Repeat reQuest (HARQ) protocol, where bidirectional limited control channels are available from sources and relays towards the destination. In the first part of the thesis, centralized node selection strategies are proposed for the second phase. The scheduling decisions are made based on the knowledge of the correctly decoded source sets of each node, with the goal to maximize the average spectral efficiency. An information outage analysis is conducted and Monte-Carlo (MC) simulations are performed to evaluate their performance. In the second part, a slow-link adaptation algorithm is proposed which aims at maximizing the average spectral efficiency under individual QoS targets for a given modulation and coding scheme family relying on the reported Channel Distribution Information of all channels. Discrete source rates are first determined using the "Genie-Aided" assumption, which is followed by an iterative rate correction algorithm. The resulting link adaptation algorithm yields performance close to the exhaustive search approach as demonstrated by MC simulations. In the third part, performances of Incremental Redundancy (IR) HARQ with Single and Multi User encoding, as well as the Chase Combining HARQ with Single User encoding are compared. MC simulations demonstrate that IR-HARQ with Single User encoding offers the best trade-off between performance and complexity for a small number of sources in our setting. Practical coding scheme is proposed and validated using MC simulations
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Tsvetanov, Kamen A. "Combining behaviour, fMRI and MR spectroscopy to study selective attention in ageing." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4191/.
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Advancing age is associated with marked atrophy in prefrontal brain structures coupled with behavioural differences across multiple cognitive domains, and yet evidence from functional neuroimaging frequently indicates overactivation for older relative to young adults. This rather paradoxical result, arising from the unimodal application of different techniques, has led to multiple theories of cognitive ageing, where each of the theories provides a unique interpretation of its technique-related findings. To overcome this we need to develop multimodal approaches where the relations between brain function and behaviour can be mapped at molecular, functional and behavioural levels. In particular, investigating the links between neuronal activity, the neurochemical environment and the effects of ageing on behaviour are essential to progress in understanding age-related deficits in cognition. Localizing neural activity with functional magnetic imaging (fMRI) provides good spatial resolution and is useful to the application of magnetic resonance spectroscopy (MRS), where a priori knowledge of the brain function is needed to investigate the concentration levels of neurotransmitters. One of the neurotransmitters measured by MRS is the main inhibitory neurotransmitter γ-Aminobyturic Acid (GABA), which has been suggested to play an important role in the modulation of cognition, neuronal activity and ageing. Therefore, one of the main aims of the thesis is to correlate GABA levels to neural activity and cognitive performance by combining GABA-edited MRS and BOLD fMRI correlates in response to a specific cognitive task in young and older adults. Furthermore, existing cognitive theories in ageing were extended with predictions about the multimodal data acquired in the thesis.
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Ghani, Sarfraz M. "Improving the Performance of Wireless Systems via Selective Interference Nulling and Adaptive Medium Access Control Design." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34041.
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Escalating demands for high performance wireless systems requires the confluence of smart communication methods, network protocols and ongoing advances in fabrication technologies, in order to bring smaller form factor mobile handsets to market. On par with these trends, this thesis focuses on two main areas, namely, Multiple Antenna Systems and Adaptive MAC Design to improve wireless system performance.
The first part of this research work presents a mathematical framework for characterizing the performance of cellular mobile radio systems equipped with smart antennas at the mobile handset to suppress a few dominant cochannel interferers (CCI) out of a total of L active independent but non-identically distributed Rayleigh faded CCI signals. Earlier works on this subject chose an unrealistic i.i.d assumption for the cochannel interferers. Since the CCI signals are of dissimilar signal strengths in practical operating environments, the premise of i.n.d fading statistics for the cochannel interferers is more realistic. In the subsequent section an analytical framework to investigate the benefits of a hybrid antenna array using selective interference nulling (SIN) and maximal ratio combining (MRC) in mobile radio environments is developed.
In the second part of this thesis, we explore the performance gains that can be achieved by exploiting the synergy resulting from the combination of the MAC and the physical layer of a wireless network. As in a traditional design, the physical layer is responsible for providing error protection for the transmission packets while the MAC layer allocates transmission bandwidth to the contending users. However, in the proposed scheme the MAC layer makes slot assignment decisions based on the channel state information (CSI) from the physical layer.Master of Science
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Ben, Salem Aymen. "The Application of Multiuser Detection to Spectrally Efficient MIMO or Virtual MIMO SC-FDMA Uplinks in LTE Systems." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30351.
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Single Carrier Frequency Division Multiple Access (SC-FDMA) is a multiple access transmission scheme that has been adopted in the 4th generation 3GPP Long Term Evolution (LTE) of cellular systems. In fact, its relatively low peak-to-average power ratio (PAPR) makes it ideal for the uplink transmission where the transmit power efficiency is of paramount importance. Multiple access among users is made possible by assigning different users to different sets of non-overlapping subcarriers. With the current LTE specifications, if an SC-FDMA system is operating at its full capacity and a new user requests channel access, the system redistributes the subcarriers in such a way that it can accommodate all of the users. Having less subcarriers for transmission, every user has to increase its modulation order (for example from QPSK to 16QAM) in order to keep the same transmission rate. However, increasing the modulation order is not always possible in practice and may introduce considerable complexity to the system. The technique presented in this thesis report describes a new way of adding more users to an SC-FDMA system by assigning the same sets of subcarriers to different users. The main advantage of this technique is that it allows the system to accommodate more users than conventional
SC-FDMA and this corresponds to increasing the spectral efficiency without requiring a higher modulation order or using more bandwidth. During this work, special attentions wee paid to the cases where two and three source signals are being transmitted on the same set of subcarriers, which leads respectively to doubling and tripling the spectral efficiency. Simulation results show that by using the proposed technique, it is possible to add more users to any SC-FDMA system without increasing the bandwidth or the modulation order while keeping the same performance in terms of bit error rate (BER) as the conventional SC-FDMA. This is realized by slightly increasing the energy per bit to noise power spectral density ratio (Eb/N0) at the transmitters.
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Carvalho, Renato Sérgio Batista. "Performance de cruzamentos de soja em gerações sucessivas de endogamia, com ênfase em produtividade, reação à ferrugem e precocidade." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-22092015-155546/.
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Entre as principais demandas da agricultura brasileira nos últimos anos, destaca-se a necessidade de cultivares de soja com elevado potencial produtivo, resistentes/tolerantes a doenças, em especial à ferrugem asiática da soja e com ciclo reduzido. O trabalho teve como objetivo principal avaliar cruzamentos de soja em diferentes gerações de endogamia e seleção, com ênfase nos caracteres produtividade de grãos, resistência/tolerância à ferrugem e ciclo (precocidade). Os 49 cruzamentos foram obtidos em um dialelo parcial 7x7, avaliados nas gerações F2 e F2:3 por Oliveira (2011) e, neste trabalho, nas gerações F2:4, F2:5, F5:6 e F5:7. Um total de dez experimentos (combinações de anos agrícolas, locais e manejos de doenças) foram realizados em blocos aumentados e ou blocos casualizados. Os dois manejos de doenças compreenderam um experimento com controle das doenças de fim de ciclo (DFC) e da ferrugem, enquanto que no segundo experimento envolveu somente o controle das DFC. Os caracteres avaliados foram: produtividade de grãos (PG), peso de cem sementes (PCS, representando o tamanho das sementes), número de dias para a maturidade (NDM), altura da planta na maturidade (APM), acamamento (AC), valor agronômico (VA), notas de severidade da ferrugem (NF) e taxas de reação à ferrugem (TRF). As TRFs foram estimadas para cada caráter por meio da diferença entre as médias ajustadas de cada genótipo nos dois experimentos com manejos de doenças. Foram realizadas análises de variância, estimativas de herdabilidade, capacidades médias de combinação (CMC), correlações das CMC entre as gerações, correlações entre caracteres, seleção de linhagens experimentais superiores e estimativas dos ganhos com a seleção. As metodologias de avaliação da resistência (NF) e da tolerância (TRF) possibilitaram a discriminação de genótipos superiores quanto à reação à ferrugem, demonstrando evidências de serem complementares e úteis para uso em conjunto. Observou-se maior tendência de haver correlações das CMC entre as gerações para caracteres de alta herdabilidade. A magnitude da variabilidade dentro de cruzamentos oscilou em consequência da seleção e da abertura de progênies e ou linhagens para a maior parte dos caracteres. Apesar das correlações entre os caracteres (NDM x PG e NDM x NF), foram observados ganhos na seleção de genótipos superiores. Os genitores que mais contribuíram para a obtenção de linhagens experimentais com alta produtividade de grãos, resistentes/tolerantes à ferrugem e precoces foram M-Soy 8001 e IAC 100 no Grupo I e USP 70.080 e USP 70.123 no Grupo II do dialelo.Among the main demands of Brazilian agriculture in recent years highlights the need for soybean cultivars with high yield potential, resistance / tolerance to diseases, mainly Asian soybean rust (FAS) and reduced cycle. The research aimed to study the genetic relationships of soybean crosses in different generations of inbreeding and selection, with an emphasis on the seed yield, resistance/tolerance to rust and cycle (earliness). The 49 crosses was obtained in a partial diallel 7x7, researching the generations F2 and F2: 3 by Oliveira (2011) and, in this work, the generations F2:4, F2:5, F5:6 and F5:7. A total of ten experiments (combinations of agricultural years, locations and disease managements) were performed in augmented block and or randomized complete-block designs. The two managements involved one experiment with control of the late season leaf diseases (DFC) and rust, whereas the second experiment only involved the control of the DFC. The following traits were evaluated : seed yield (PG), one hundred seed weight (PCS, representing the seed size), number of days to maturity (NDM), plant height at maturity (APM), lodging (AC), agronomic value (VA), notes of rust severity (NF) and the rust reaction rates (TRF). The TRFs for each trait were estimated by the difference between the adjusted means of each genotype in the two experiments with diseases managements. There were obtained analyses of variance and estimates of heritability, average combining ability (CMC), the CMC correlations between generations, correlations between traits, selection of superior experimental lines and the selection gains. The methodologies for measuring the rust resistance by severity notes (NF) and the rust tolerance (TRF) allowed the discrimination of genotypes and showed evidences of being complementary and with benefits for use together. Higher evidences of CMC correlations between generations were observed in the high heritability traits. The magnitude of the variability within crosses oscillated due the selection and the progeny/line opening, for most of the traits. Even with negative correlations between traits ( NDM x PG and NDM x NF), there were observed gains in the selection of superior genotypes. The parents who contributed most to obtain experimental lines with high seed yield, rust resistance / tolerance and earliness were M-Soy 8001 and IAC 100 in the Group I, and USP 70.080 and USP 70.123 in the Group II of the diallel.
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Green, Paula. "Studies of combining specificities of endogenous lectins : mannose-6-phosphate receptor, L-selectin and mannan-binding protein." Thesis, Open University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333975.
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Segkos, Michail. "Advanced techniques to improve the performance of OFDM Wireless LAN." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSegkos.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Applied Physics)--Naval Postgraduate School, June 2004.Thesis advisor(s): Tri T. Ha, Brett H. Borden. Includes bibliographical references (p. 107-109). Also available online.
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Ong, Choon Kwee. "Performance analysis of DPSK signals with selection combing and convolutional coding in fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA344673.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1998."June 1998." Thesis advisor(s): Tri T. Ha, Ralph D. Hippenstiel. Only one copy of this Thesis was sent, still waiting for second copy. Includes bibliographical references (p. 55-56). Also available online.
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Chi, Xuan. "The Impact of Channel Estimation Error on Space-Time Block and Trellis Codes in Flat and Frequency Selective Channels." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33963.
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Recently multiple antenna systems have received significant attention from researchers as a means to improve the energy and spectral efficiency of wireless systems. Among many classes of schemes, Space-Time Block codes (STBC) and Space-Time Trellis codes (STTC) have been the subject of many investigations.Both techniques provide a means for combatting the effects of multipath fading without adding much complexity to the receiver. This is especially useful in the downlink of wireless systems. In this thesis we investigate the impact of channel estimation error on the performance of both STBC and STTC.
Channel estimation is especially important to consider in multiple antenna systems since (A) for coherent systems there are more channels to estimate due to multiple antennas and (B) the decoupling of data streams relies on correct channel estimation. The latter effect is due to the intentional cross-talk introduced into STBC.
Master of Science
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Šilhavá, Jana. "Metody pro predikci s vysokodimenzionálními daty genových expresí." Doctoral thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-261222.
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Dizertační práce se zabývá predikcí vysokodimenzionálních dat genových expresí. Množství dostupných genomických dat významně vzrostlo v průběhu posledního desetiletí. Kombinování dat genových expresí s dalšími daty nachází uplatnění v mnoha oblastech. Například v klinickém řízení rakoviny (clinical cancer management) může přispět k přesnějšímu určení prognózy nemocí. Hlavní část této dizertační práce je zaměřena na kombinování dat genových expresí a klinických dat. Používáme logistické regresní modely vytvořené prostřednictvím různých regularizačních technik. Generalizované lineární modely umožňují kombinování modelů s různou strukturou dat. V dizertační práci je ukázáno, že kombinování modelu dat genových expresí a klinických dat může vést ke zpřesnění výsledku predikce oproti vytvoření modelu pouze z dat genových expresí nebo klinických dat. Navrhované postupy přitom nejsou výpočetně náročné. Testování je provedeno nejprve se simulovanými datovými sadami v různých nastaveních a následně s~reálnými srovnávacími daty. Také se zde zabýváme určením přídavné hodnoty microarray dat. Dizertační práce obsahuje porovnání příznaků vybraných pomocí klasifikátoru genových expresí na pěti různých sadách dat týkajících se rakoviny prsu. Navrhujeme také postup výběru příznaků, který kombinuje data genových expresí a znalosti z genových ontologií.
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Lu, Tongda, Jiawen Ji, and Jingming Zhang. "An empirical study of the co-branding partner selection strategy : A perception from the negative perspective combing with consumer psychology." Thesis, Internationella Handelshögskolan, Jönköping University, IHH, Företagsekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-48948.
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In recent years, the fashion industry has set off a trend of co-branding, and co-branding has become a unique marketing strategy for major brands to obtain benefits. However, there are potential risks when brands are selecting joint partners. The literature in this paper addresses both the positive effects of co-branding and how it is viewed from a business and customer perspective related to customer loyalty. Besides, previous researches on how to correctly select joint partners have not been explored in the collected literature. Therefore, the purpose of this study is to provide a deeper understanding of the strategy of choosing partners for brands from a negative aspect under the current trend of brand cooperation，and to propose relevant implications through case analysis. The research method used in this paper is qualitative research by conducting case studies and four focus groups. The findings indicate that communication and connection are the basis for two brands to having success. Furthermore, the enterprise needs to evaluate and estimate the capabilities of the partners by analyzing the external environment and opportunities. Besides, with the help of co-brand partners, brands can make up for their shortcomings and work together to achieve the expected goal.
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Barbier, Maxime. "Histoire évolutive et propagation de la tuberculose à échelle planétaire : vers une approche intégrée combinant la génomique des populations et le typage multi-locus." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEP051/document.
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D’après un rapport de l’OMS, la tuberculose reste en 2015 l’une des 10 premières causes de décès à l’échelle mondiale. De ce fait, en matière de santé, éradiquer la maladie à l’horizon 2030 est un des objectifs majeurs fixés par les Nations Unies. La bactérie responsable de cette infection, Mycobacterium tuberculosis, est un pathogène obligatoire dont l’origine et l’évolution sont intrinsèquement liées à celles de son hôte principal, Homo sapiens. En effet, les souches actuelles de tuberculose présentent, tout comme l’homme, une forte structure phylogénétique, trace de leur origine géographique. Les pays pauvres et en développement sont les plus touchés par l’épidémie globale, favorisée par des systèmes de santé défaillants et une haute prévalence du VIH. Les pays occidentaux ne sont pas épargnés, menacés par l’émergence de souches de plus en plus résistantes aux antibiotiques provenant en grande partie de l’ex URSS. Au cours de cette thèse, j’analyse l’histoire évolutive, la propagation et l’acquisition de résistances aux antibiotiques de plusieurs épidémies de tuberculose en me basant sur des données génétiques et génomiques. Dans un premier temps je m’intéresse aux effets d’une campagne nationale de traitements en Asie Centrale sur le développement de souches multi-résistantes et met également en lumière le rôle clef de certaines mutations dans le succès des clones présentés. Ainsi cette campagne a été partiellement mise en échec par la présence de souches pré-résistantes, grâce à la survenue de mutations avant même la mise en place des traitements antibiotiques. Par la suite je me suis focalisé sur un clade particulier de souches multi-résistantes, le clone Russe W148. Je présente sa dispersion géographique et temporelle à travers l’Eurasie et démontre l’importance des mutations compensatoires dans son succès épidémique. De plus, la tuberculose ne touche pas seulement les hommes mais infecte également plusieurs autres mammifères. Afin d’appréhender les contraintes adaptatives accompagnants ces changements d’hôtes, j’ai effectué divers tests de sélection dans le but d’identifier les gènes impliqués. Pour finir, nous avons développé un indice souche spécifique, permettant de mesurer le succès épidémique de celles-ci à un niveau individuel. Dans le cadre d’études épidémiologiques, cette mesure peut être croisée avec des informations sur le patient, la souche ou même socio-économiquesAccording to a 2015 WHO report, tuberculosis remains one of the top 10 causes of death worldwide. Despite considerable efforts by the United Nations to eradicate the disease by 2030, a global TB epidemic still persists. Its causative agent, the bacterium Mycobacterium tuberculosis, an obligate pathogen, has been plaguing humanity since it originated, and has coevolved with its main host, Homo sapiens, over thousands of years. Contemporary tuberculosis strains exhibit a structured phylogeographic pattern, carrying the genetic print of their geographic origin. The Koch bacillus infects and kills in large numbers, in poor and developing countries, where fragile health care systems, combined with high HIV prevalence, facilitate epidemic spread. In western countries, the major current threats are the multiplication and propagation of antibiotic resistant strains (MDR/XDR) coming predominantly from former Soviet republics. In this thesis, I unravel the evolutionary history, propagation, and acquisition of drug resistance-conferring mutations in different settings, by implementing multiple genetic and genomic data sets. First, focusing on Central Asia, using whole genome sequencing and Bayesian statistics, I assess the effects of a treatment campaign on the development of MDR strains and highlight key mutations in successful strains. More importantly, the success of DOTs campaigns was compromised by the genetic make-up of these outbreak clades (pre-treatment low frequency resistance SNPs). Special attention was also given to a particular outbreak of MDR strains, i.e. the Russian W148 clone. I present its westward spatial and temporal propagation at a continental scale during the last century, and underline the key contribution of compensatory mutations in its epidemic success. However, tuberculosis does not only infect humans, but also has experienced successive mammalian host jumps. To decipher the adaptive constraints accompanying such secondary events, a systemic gene screen with selection signature-detecting algorithms was implemented to identify putative targets during diversifying selection. Finally, novel mathematical tools and indices that reflect the epidemicity of a strain were developed, jumping from a population-driven approach to a strain specific one, with broader epidemiological applications. This allows us to correlate strain fitness with patient, lineage, and socio-economic information
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Morel, Daphné. "Identifying Synthetic Lethal and Selective Approaches to Target PBRM1-Deficiency in Clear Cell Renal Cell Carcinoma PBRM1 Deficiency in Cancer is Synthetic Lethal with DNA Repair Inhibitors Exploiting Epigenetic Vulnerabilities in Solid Tumors: Novel Therapeutic Opportunities in the Treatment of SWI/SNF-Defective Cancers Combining Epigenetic Drugs with other Therapies for Solid Tumours — Past Lessons and Future Promise Targeting Chromatin Defects in Selected Solid Tumors Based on Oncogene Addiction, Synthetic Lethality and Epigenetic Antagonism." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL017.
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L’inactivation de polybromo-1 (PBRM1) est un évènement fréquent dans de nombreux cancers. En particulier, les carcinomes rénaux à cellules claires présentent une déficience en PBRM1 dans 40 à 50% des cas. A ce jour, il n’existe pas d’approche de médecine précision connue capable de cibler spécifiquement les cellules tumorales déficientes en PBRM1.Pour identifier des cibles de létalité synthétique associées à la perte de PBRM1, nous avons (i) réalisé un criblage pharmacologique à haut débit évaluant la sensibilité à 167 molécules dans un modèle cellulaire isogénique pour PBRM1, et (ii) étudié l’impact transcriptomique et protéomique de la perte de PBRM1 dans ce même modèle.Nous avons ensuite caractérisé les mécanismes sous-jacents à la relation de létalité synthétique découverte.Nous avons identifié et validé une relation de létalité synthétique existante entre la perte tumorale de PBRM1 et l’inhibition pharmacologique de PARP, pouvant être potentialisée par l’ajout d’un inhibiteur d’ATR.Cette relation de létalité synthétique était caractérisée par un niveau basal élevé de stress cellulaire chez les cellules déficientes en PBRM1, associant anomalies mitotiques, stress transcriptionnel et stress réplicatif – tous ces phénomènes étant exacerbés à l’ajout d’inhibiteurs de PARP, jusqu’à dépasser les capacités cellulaires à maintenir un phénotype compatible avec la survie.Ces observations apportent la preuve de concept préclinique que les inhibiteurs de PARP sont de potentiels candidats thérapeutiques pour cibler spécifiquement les tumeurs déficientes en PBRM1Polybromo-1 (PBRM1) inactivation occurs in multiple malignancies and is of particular importance in clear cell renal cell carcinomas (ccRCC), as it drives 40 to 50% of cases. Currently, no precision-medicine approach uses PBRM1 deficiency to specifically target tumour cells. To uncover novel synthetic lethal approaches to treat PBRM1-defective cancers, we performed (i) a high-throughput pharmacological screening, evaluating the sensitivity to 167 small molecules in a PBRM1-isogenic cellular model, and the (ii) systematic mapping of the whole transcriptomic and proteomic profiles associated with PBRM1 loss-of-function within this model. We further investigated the mechanism underlying this synthetic lethal relationship.We identified and validated synthetic lethal effects between PBRM1 loss and both PARP and ATR inhibition. Combinatorial use of PARP with ATR inhibitors exerted additive cytotoxic effects in PBRM1-defective tumor cells. These synthetic lethal relationships were characterized by a pre-existing replication stress in PBRM1-deficient cells associated with mitosis and DNA damage repair abnormalities, which were exacerbated upon PARP inhibition selectively in PBRM1-defective cells.These data provide the preclinical basis for evaluating PARP inhibitors as a monotherapy or in combination in patients with PBRM1-deficient ccRCC
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Kuo, Yen-Ming, and 郭彥銘. "Combining Feature Selection and Instance Selection in Sentiment Analysis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/y7e529.
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碩士國立中正大學
資訊管理系研究所
104
In recent years, due to advances of new technological product (e.g., smart phone, table, etc.), the mobile device has become more popular and created a new community model which affected everyone’s life. Sentiment analysis through analyze the text people write on the web then can guess the emotion they represented at that time can be applied to many different fields of research. Since, sentiment analysis is one of popular research topics today and many researchers devote to propose a way to increase classification accuracy. Hence, feature selection and instance selection in sentiment analysis are used in my research. Three datasets which is public and different sizes from twitter are collected in this research. We used feature selection to select attributes as a representative and reduce the dimension. Moreover, we added instance selection to select instance as a representative and reduce the number of instance. At last, we used J48, Naïve Bayes and simple logistic methods to build prediction models, and compare with base-line. The results show that, if we added feature selection and instance selection, the emotion classification accuracy will be better than traditional methods. And we also found that there are two factors which affect the results, one is the size of datasets and the other is instance selection. In addition, the better result we will get in big dataset when we choose DROP3 of instance selection.
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Wolf, Lior, and Stanley Bileschi. "Combining Variable Selection with Dimensionality Reduction." 2005. http://hdl.handle.net/1721.1/30531.
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This paper bridges the gap between variable selection methods (e.g., Pearson coefficients, KS test) and dimensionality reductionalgorithms (e.g., PCA, LDA). Variable selection algorithms encounter difficulties dealing with highly correlated data,since many features are similar in quality. Dimensionality reduction algorithms tend to combine all variables and cannotselect a subset of significant variables.Our approach combines both methodologies by applying variable selection followed by dimensionality reduction. Thiscombination makes sense only when using the same utility function in both stages, which we do. The resulting algorithmbenefits from complex features as variable selection algorithms do, and at the same time enjoys the benefits of dimensionalityreduction.1
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Yi-Wei, Chen. "Combining SVMs with Various Feature Selection Strategies." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1107200513131700.
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Chen, Yi-Wei, and 陳奕瑋. "Combining SVMs with Various Feature Selection Strategies." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/94847510804922841814.
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碩士國立臺灣大學
資訊工程學研究所
93
Feature selection is an important issue in many research areas. There are some reasons for selecting important features such as reducing the learning time, improving the accuracy, etc. This thesis investigates the performance of combining support vector machines (SVM) and various feature selection strategies. The first part of the thesis mainly describes the existing feature selection methods and our experience on using those methods to attend a competition. The second part studies more feature selection strategies using the SVM.
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Hsiao, Yu-Chieh, and 蕭鈺潔. "Stock Prediction by Combining Multiple Feature Selection Methods." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/00304036090036697532.
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碩士國立中正大學
會計與資訊科技研究所
97
Stock investment has become a popular investment activity in Taiwan. To effectively predict stock price for investors, it is a very important research problem and challenging. In literature, data mining techniques have been applied to stock price prediction. As feature selection is an important pre-processing step to select more representative variables for effective prediction, previous studies do not take all relevant variables into consideration seriously. In addition, they do not attempt to further combine multiple feature selection methods to filtering out more redundant variables. Therefore, the thesis takes fundamental indexes and macroeconomic indexes into consideration based on the TEJ dataset. Artificial Neural Network (ANN) is applied as the base-line prediction model. In particular, three well-known feature selection methods, which are principal component analysis (PCA), genetic algorithms (GA) and Decision Tree (DT), are used to filter out the redundant variables individually. Regarding the experimental result in this thesis, the combination of PCA and GA and the multi-intersection combination approach provide the better prediction performances. No matter the number of variables, the accuracy and the error rate for predicting stocks rise, these two models perform the best.
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Wang, Chun-Chi, and 王俊祺. "Genetic Algorithm combining Risky Analysis for Stock Selection System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/32286058382739360276.
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碩士國立暨南國際大學
資訊工程學系
102
In the study, We proposed a stock selection method, based on the theories “Portfolio Selection” and “A Theory of Market Equilibrium under Conditions of Risk” proposed in 1952 and 1964 respectively, by the Economist Nobel Prize-winner in 1990, Harry Markowitz and William F. Sharpe. We used the methods proposed how to assess the risk value, the expected rate of return and Sharpe indicator used to assess the risk of over-expected of units. Then using Genetic Algorithm(GA) to find the best solution for all stock portfolios based on the fitness function which was designed with the risk of over-expected of units based from Sharpe indicator. For finding which set of parameters is the optimal for solving the stock selection problem using GA and which method of stock portfolios is the best, we also made a lot of experiments to find the most optimal set of parameters and the best method of stock portfolio. Finally, we could get a stock portfolio which could give consideration to risk and the return of investment.
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Lien, Hsin-Chung, and 連信仲. "Combining Feature Selection with Decision Theory for Yarn Grading." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/75613754882714006806.
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博士國立中央大學
機械工程研究所
91
The present research investigates a simple and effective system for grading textile yarns by pattern recognition theory. During the learning processes of textile yarn grading, yarn property vectors (PVs) can be transferred to the principal axis vector (PAV) of the orthonormal function with Karhunen-Loeve (K-L) expansion, so as to select features and then reduce dimensions. Whereas, through the Bayes Classifier (BC) or the Minimum Distance (MD) method, the decision function for evaluating textile yarns grading can be obtained. Then under the premise of not sacrificing identification rate, the learning process can be repeated to search for the transfer matrix and the decision function with PAVs of the lowest identifiable dimension. The present system is shown to create a quick and effective grading system for textile yarns by using PAVs of only one dimension, thus both simplifying the identification system and providing objective grading results. The grade of textile yarns is an important index in evaluating the yarn’s market value. This paper uses the backpropagation neural network (BNN) and Karhunen-Loeve (K-L) expansion method to construct a new and highly accurate grading system. Outcomes show that a highly accurate and neutral grading system can be obtained if the BNN learning sample is comprehensive or by adopting BNN with relearning technique (Self-Healing). Considering the possibility of reducing the dimension of BNN input vectors without losing the accuracy, this paper preprocesses the BNN grading system using the K-L expansion. Experiments demonstrate that the K-L expansion provides a way to reduce the input dimensions, and that a single principle axis value of BNN with K-L expansion grading system is able to grade textile yarns. In addition, the experiment demonstrates that as the input dimensions are reduced to four in a self-healing neural network with K-L expansion, the grading system provides the high accuracy and robustness. By using the effective distance between clusters (EDC) as the basis for feature selection, this paper achieves a significant and effective feature for textile yarn grading, and further upgrades the operational efficiency of such grading. The results, such as the feature selection processing to principal axis vectors (PAVs) by EDC, show that The features’ average number and average total distance of mistaken ranking by EDC were only 33.3% and 16.7% of those by the Karhunen-Loeve (K-L) expansion, respectively. Furthermore, EDC can be applied directly to the feature selection of property vectors (PVs) and reduce the measured items of PVs without lowering the identification precision. Compared with the textile yarn grading proposed earlier, EDC provides 16.7% greater efficiency both in measuring PVs and in calculating PAV1 time.
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Tu, Jhih-yu, and 塗智宇. "Combining SWRL with User Profile in Web Service Selection." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/t3t73a.
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碩士國立中央大學
軟體工程研究所
97
Selecting suitable web services is difficult, as the search usually gives enormous unsuitable results. In order to enhance precision of the selection, this paper presents a Semantic Web Service Selector, which combines semantic web rule language (SWRL) with user profile. The selector compares with the semantics of OWL-S based web services to select the web services that fit user’s requirement. Whenever a web service is modified, the service ontology can obtain its latest information from the universal referential identifier (URI) to ensure that all the services can be used.
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Yuan, Wei-Cheng, and 袁瑋成. "Nowcasting Inflation by Combining Variable Selection and Mixed Frequency Methods." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ztxs43.
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Chou, Chen-Wei, and 周承緯. "Study of Receiver and Transmit Selection-Combining Schemes for MIMO Systems." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/79399031613945861052.
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碩士國立暨南國際大學
通訊工程研究所
97
In the MIMO system, using the selection combining technique can improve the performance of the STBC scheme. Therefore, the three research topics of this thesis are all related to the STBC scheme with selection combining. In the first research topic of this thesis, we study several selection criteria for the selection combining technique. We found that these selection criteria can result in the further performance improvements or can simplify the implementations. The second research topic of this thesis incorporates the transmit antenna selection into the selection combining technique. Simulation results show that such an integration of the receive antenna selection and the transmit antenna selection can further reduce the bit error probability. The selection combining technique needs to know the channel information, thus the third research topic of this thesis deals with the channel estimation for the selection combining technique. We found from simulation results that the accuracy of the channel information can affect the performance of the selection combining technique.
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Chen, Tzu-Li, and 陳子立. "Combining Feature Selection with Coefficient of Determination to Grow Model Trees." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/28047601362583479751.
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碩士國立成功大學
工業管理科學系碩博士班
91
Model trees are similar to decision trees, while they have a linear regression model at each leaf node for prediction, instead of a majority class for classification. It is a useful method for realistic numeric prediction problems. The growing procedure of the model tree is based on a measure called standard deviation reduction (SDR). The property of the SDR will gather instances with relatively close class values into the same node to derive linear regression models. Growing model trees in this way does not consider the linear relations between attributes and class, hence may distort the meanings of data. Thus, we define a new measure called FAR, which quotes the concept of feature selection and coefficient of determination to consider the linear relations between the attribute values and the class values, to grow model trees. This new scheme hopefully could mine more valuable information for the problems of interest. Our experimental results show that the model trees grown by the FAR achieve almost the same prediction accuracy as the ones grown by the SDR and generally have a smaller size to make the interpretation on the learning results easier.
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Chen-HaoKuo and 郭宸豪. "Combining Correlation Induction and Control Variates in Screening and Selection Procedures." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/76595930276664800928.
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碩士國立成功大學
工業與資訊管理學系碩博士班
98
The propose of using Ranking and Selection Procedures is to find superior systems form all of candidate systems. However, if the variance of system output is large, we need to sampling more sample to find best system to guarantee confidence level. Therefore, we apply Variance Reduction Technique to procedures, replacing the origin estimator, sample mean, to accomplish the propose of reducing variance; and further, decrease the number of samples we need. In our research, we establish four model of combining Correlation Induction and Control Variates in Screening Procedure, Multistage Selection Procedure, Two-stage Selection Procedure, and Fully Sequential Selection Procedure, and by inference or proving that each procedure will guarantee confidence level, and we also analyze in what condition our combine procedure will be better than CV procedure. Through empirical results and a realistic illustration, we find that the probability of correct selection of all procedures will conform to confidence level guarantee, and when the problem is more complicated, then we can get more benefit form our combine procedures. In the end of our research we conclude that, for Screening Procedure, we recommend using Model 3 when the number of samples and the number of controls is close; using Model 4 when the problem is complex with setting large samples to do; in the other condition we suggest using Model 1. For Multistage Selection Procedure and Fully Sequential Selection Procedure, we recommend using Model 1 when facing a complicated problem, but otherwise using the CV procedure. Finally, for Two-stage Procedure we recommend using Model 1 in all situations.
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Huang, Jian-Kai, and 黃建凱. "Combining technical indicators and feature selection methods to predict Bitcoin price." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/qccd3r.
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碩士國立東華大學
資訊管理學系
107
With the rapid development of blockchain, cryptocurrency has attracted more and more attention. Bitcoin has become the most popular virtual currency in recent years. Many investors regard bitcoin as a stock-like investment tool. However, the price of Bitcoin fluctuates drastically, the investors can not accurately predict the price of Bitcoin. In view of the fact that technical indicators can effectively predict stock prices and feature extraction methods are helpful in forecasting stock price and bankruptcy, we propose using 24 popular stock market technical indicators, e.g., Moving Average Convergence Divergence(MACD), Bollinger Bands, Stochastic Oscillator(KD), Williams %R(W%R), to predict the price of bitcoin. Next, six feature selection methods e.g., Information gain, Principal components analysis, are used to select more useful indicators. Finally, eight classification algorithms and five prediction algorithms are employed to predict the trend of bitcoin price and the bitcoin price. The experiments uses the sliding window scheme to maintain the temporal correlation of training data and test data. The experiment results show that the technical indicator can effectively predict Bitcoin price and also indicate the technical indicators and algorithms which are effective in prediction.