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Title: The Frequency of The Twelve Verb Tenses in Academic Papers Written by Native Speakers.
Creator: Alzuhairy, Uthman, Folse, Keith, Farina, Marcella, Vitanova-Haralampiev, Gergana, University of Central Florida
Abstract / Description: Because of the significant and sensitive role of verb tenses in learning English, the current study examined the occurrence of the twelve verb tenses that native writers (NWs) utilized in their selected academic papers at the college level. In doing so, the study created a baseline of relative frequency of verb tense usage that may benefit further studies, especially those connected with the teaching grammar to English learners. The main linguistic items targeted for tabulation in this study...
Show moreBecause of the significant and sensitive role of verb tenses in learning English, the current study examined the occurrence of the twelve verb tenses that native writers (NWs) utilized in their selected academic papers at the college level. In doing so, the study created a baseline of relative frequency of verb tense usage that may benefit further studies, especially those connected with the teaching grammar to English learners. The main linguistic items targeted for tabulation in this study were the 12 verb tenses, modals, perfect modals, and imperatives. These items were elicited from an original corpus of 31 research papers written by undergraduate students studying at UCF. The total size of this original corpus is 103,181 words, with the length of papers varying from 1,964 words to 6,676 words. In order to analyze the data and facilitate a more accurate counting process, the researchers used a code coloring method.The results revealed that the most frequently used tenses were present simple, past simple, modals, and present perfect, while future progressive, future perfect, and past and future perfect progressive were almost never used by NWs. These findings could contribute toward the development of the methodology of teaching verb tenses as well as help English learners to comprehend and master this important grammatical area. The pedagogical implication of these results is in improving the teaching of the verb tenses to English learners, as it accentuates the difference between which of the twelve verb tenses could be given more class time as well as those that could be given less attention.
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Date Issued: 2016
Identifier: CFE0006435, ucf:51474
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006435

Title: THE EFFECT OF NEIGHBORHOOD SIZE AND MORPHOLOGY IN THE CHINESE LANGUAGE.
Creator: Nguyen, Long, Sims, Valerie, University of Central Florida
Abstract / Description: The Neighborhood Size Effect (NSE), characterized as the effect in word determination based on changing one orthographic aspect of that word. The amount of words that can be created through such manipulation is called a neighborhood size (NS). Number of other factors such as frequency, how often a word appears and morphology, the combination of meaningful word units, have been suggested to have an overriding effect on NSE. In addition, there is a lack of research on NSE with non-alphabetical...
Show moreThe Neighborhood Size Effect (NSE), characterized as the effect in word determination based on changing one orthographic aspect of that word. The amount of words that can be created through such manipulation is called a neighborhood size (NS). Number of other factors such as frequency, how often a word appears and morphology, the combination of meaningful word units, have been suggested to have an overriding effect on NSE. In addition, there is a lack of research on NSE with non-alphabetical languages such as Chinese, which uses characters comprising of a multitude of semantic or phonetic markers. In this experiment, participants coming from mainland China were presented with 60 individual characters and 59 characters with Chinese morphology made up of two characters which form single words. Both conditions, were manipulated with NS by adjusting the semantic or phonetical radical within a character and with frequency by using a website that measures how frequent a character appeared within the language. Both character conditions were found to have a significant effect with frequency and neighborhood size (NS) with characters with higher frequency and lower NS found to have higher accuracy and lower reaction times. With low frequency single characters, it was that those with higher neighborhood size had greater delay in reaction time and lower accuracy. With low frequency morphologically constructed characters, it was found that lower neighborhood size had higher accuracy, but no significant result with regards to reaction time. Due to differing accuracy results with NS and character condition, it is suggested that further factors such as morphological processing in single characters and bigram frequency in morphologically constructed characters might have an effect on word determination in conjunction with neighborhood size. Thus, it is a possibility that Chinese morphological may depend more on other factors than neighborhood size.
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Date Issued: 2016
Identifier: CFH2000098, ucf:45556
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000098

Title: APPROXIMATING THE SPECTRAL WIDTH OF IRRADIANCE FLUCTUATIONS WITH QUASI-FREQUENCY.
Creator: Reel, Andrew, Andrews, Larry, University of Central Florida
Abstract / Description: Under weak turbulence theory, we will use the random thin phase screen model and the Kolmogorov power-law spectrum to derive approximate models for the scintillation index, covariance function of irradiance fluctuations, and temporal spectrum of irradiance fluctuations for collimated beams. In addition, we will provide an expression for the quasi-frequency of a collimated beam and investigate the relationship between the quasi-frequency and the maximum width of the normalized temporal...
Show moreUnder weak turbulence theory, we will use the random thin phase screen model and the Kolmogorov power-law spectrum to derive approximate models for the scintillation index, covariance function of irradiance fluctuations, and temporal spectrum of irradiance fluctuations for collimated beams. In addition, we will provide an expression for the quasi-frequency of a collimated beam and investigate the relationship between the quasi-frequency and the maximum width of the normalized temporal spectrum of irradiance for a collimated beam.
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Date Issued: 2008
Identifier: CFE0002047, ucf:47595
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002047

Title: THE WAVE STRUCTURE FUNCTION AND TEMPORAL FREQUENCY SPREAD IN WEAK TO STRONG OPTICAL TURBULENCE.
Creator: Masino, Aaron Joseph, Young, Cynthia Y., University of Central Florida
Abstract / Description: This paper presents analytic expressions for the wave structure function, frequency spread of the temporal frequency spectrum, and the temporal frequency spectrum of optical signals propagating through a random medium, specifically the Earth's atmosphere. The results are believed to be valid for all optical turbulence conditions. These expressions are developed using the Rytov approximation method. Generally, the validity of statistical quantities obtained via this method is restricted to...
Show moreThis paper presents analytic expressions for the wave structure function, frequency spread of the temporal frequency spectrum, and the temporal frequency spectrum of optical signals propagating through a random medium, specifically the Earth's atmosphere. The results are believed to be valid for all optical turbulence conditions. These expressions are developed using the Rytov approximation method. Generally, the validity of statistical quantities obtained via this method is restricted to conditions of weak optical turbulence. However, in this work, by using a modification of the effective atmospheric spectral model presented by Andrews et al. for scintillation index, wave structure function expressions have been derived that are valid in all turbulence conditions as evidenced by comparison to experimental data. Analytic wave structure function results are developed for plane, spherical, and Gaussian-beam waves for one-way propagation. For the special case of a spherical wave, comparisons are made with experimental data. The double pass case is also considered. Analytic expressions for the wave structure function are given that incorporate reflection from a smooth target for an incident spherical wave. Additionally, analytic expressions for the frequency spread of the temporal frequency spectrum and the temporal frequency spectrum itself, after one-way propagation for horizontal and slant paths, are derived for plane and spherical waves. These results are also based on the Rytov perturbation method . Expressions that are believed to be valid in all turbulence conditions are also developed by use of the effective atmospheric spectral model used in the wave structure function development. Finally, double pass frequency spread expressions are also presented. As in the case of the wave structure function, reflection from a smooth target with an incident spherical wave is considered.
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Date Issued: 2004
Identifier: CFE0000073, ucf:46106
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000073

Title: DESIGN AND DEMONSTRATION OF MEANDERLINE RETARDERS AT INFRARED FREQUENCIES.
Creator: Tharp, Jeffrey, Boreman, Glenn, University of Central Florida
Abstract / Description: Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral...
Show moreMeanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. Several novel applications are identified, including integrated circular polarizers, reflective waveplates, and large-area polarization tags.
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Date Issued: 2007
Identifier: CFE0001884, ucf:47396
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001884

Title: Large Area Conformal Infrared Frequency Selective Surfaces.
Creator: Darchangel, Jeffrey, Schoenfeld, Winston, Boreman, Glenn, Likamwa, Patrick, Kik, Pieter, Lail, Brian, University of Central Florida
Abstract / Description: Frequency selective surfaces (FSS) were originally developed for electromagnetic filtering applications at microwave frequencies. Electron-beam lithography has enabled the extension of FSS to infrared frequencies; however, these techniques create sample sizes that are seldom appropriate for real world applications due to the size and rigidity of the substrate. A new method of fabricating large area conformal infrared FSS is introduced, which involves releasing miniature FSS arrays from a...
Show moreFrequency selective surfaces (FSS) were originally developed for electromagnetic filtering applications at microwave frequencies. Electron-beam lithography has enabled the extension of FSS to infrared frequencies; however, these techniques create sample sizes that are seldom appropriate for real world applications due to the size and rigidity of the substrate. A new method of fabricating large area conformal infrared FSS is introduced, which involves releasing miniature FSS arrays from a substrate for implementation in a coating. A selective etching process is proposed and executed to create FSS particles from crossed-dipole and square-loop FSS arrays. When the fill-factor of the particles in the measurement area is accounted for, the spectral properties of the FSS flakes are similar to the full array from which they were created. As a step toward scalability of the process, a square-patch design is presented and formed into FSS flakes with geometry within the capability of ultraviolet optical lithography.Square-loop infrared FSS designs are investigated both in quasi-infinite arrays and in truncated sub-arrays. First, scattering-scanning near-field optical microscopy (s-SNOM) is introduced as a characterization method for square-loop arrays, and the near-field amplitude and phase results are discussed in terms of the resonant behavior observed in far-field measurements. Since the creation of FSS particles toward a large area coating inherently truncates the arrays, array truncation effects are investigated for square-loop arrays both in the near- and far-field. As an extension of the truncation study, small geometric changes in the design of square-loop arrays are introduced as a method to tune the resonant far-field wavelength back to that of the quasi-infinite arrays.
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Date Issued: 2014
Identifier: CFE0005476, ucf:50348
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005476

Title: FREQUENCY DOMAIN INDEPENDENT COMPONENT ANALYSIS APPLIED TO WIRELESS COMMUNICATIONS OVER FREQUENCY-SELECTIVE CHANNELS.
Creator: Liu, Yuan, Mikhael, Wasfy, University of Central Florida
Abstract / Description: In wireless communications, frequency-selective fading is a major source of impairment for wireless communications. In this research, a novel Frequency-Domain Independent Component Analysis (ICA-F) approach is proposed to blindly separate and deconvolve signals traveling through frequency-selective, slow fading channels. Compared with existing time-domain approaches, the ICA-F is computationally efficient and possesses fast convergence properties. Simulation results confirm the effectiveness...
Show moreIn wireless communications, frequency-selective fading is a major source of impairment for wireless communications. In this research, a novel Frequency-Domain Independent Component Analysis (ICA-F) approach is proposed to blindly separate and deconvolve signals traveling through frequency-selective, slow fading channels. Compared with existing time-domain approaches, the ICA-F is computationally efficient and possesses fast convergence properties. Simulation results confirm the effectiveness of the proposed ICA-F. Orthogonal Frequency Division Multiplexing (OFDM) systems are widely used in wireless communications nowadays. However, OFDM systems are very sensitive to Carrier Frequency Offset (CFO). Thus, an accurate CFO compensation technique is required in order to achieve acceptable performance. In this dissertation, two novel blind approaches are proposed to estimate and compensate for CFO within the range of half subcarrier spacing: a Maximum Likelihood CFO Correction approach (ML-CFOC), and a high-performance, low-computation Blind CFO Estimator (BCFOE). The Bit Error Rate (BER) improvement of the ML-CFOC is achieved at the expense of a modest increase in the computational requirements without sacrificing the system bandwidth or increasing the hardware complexity. The BCFOE outperforms the existing blind CFO estimator [25, 128], referred to as the YG-CFO estimator, in terms of BER and Mean Square Error (MSE), without increasing the computational complexity, sacrificing the system bandwidth, or increasing the hardware complexity. While both proposed techniques outperform the YG-CFO estimator, the BCFOE is better than the ML-CFOC technique. Extensive simulation results illustrate the performance of the ML-CFOC and BCFOE approaches.
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Date Issued: 2005
Identifier: CFE0000756, ucf:46560
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000756

Title: The Frequency of the Passive Voice in Freshman Academic Books.
Creator: Moreb, Basma, Folse, Keith, Mihai, Florin, Young, Beth, University of Central Florida
Abstract / Description: The use of passive voice has long been an area of difficulty for English learners. Celce-Murcia (&) Larsen-Freeman (2015) noted that it is learning when to use the English passive that presents the greatest long-term challenge to ESL/EFL students(") (p. 352). Because textbooks are a source of language input for English learners, this study investigated the frequency of passive voice verbs in samples from four academic textbooks in courses commonly taken by freshmen. The study also examined...
Show moreThe use of passive voice has long been an area of difficulty for English learners. Celce-Murcia (&) Larsen-Freeman (2015) noted that it is learning when to use the English passive that presents the greatest long-term challenge to ESL/EFL students(") (p. 352). Because textbooks are a source of language input for English learners, this study investigated the frequency of passive voice verbs in samples from four academic textbooks in courses commonly taken by freshmen. The study also examined whether there are significant differences between the frequencies by textbook. The data was collected from four General Education Plan (GEP) subject textbooks used in freshman classes at a large metropolitan university in the southeastern United States, namely English composition, history, psychology, and biology. The data was then compiled into a corpus of approximately 20,000 words created specifically for the current study, with 5,000 words randomly and sequentially selected from each of the four textbooks. The study utilized a table created by Folse (2009) to analyze differences between the basic passive voice tenses found in the textbooks. The study examined the be-passives, get-passives, and have-passives and their frequency in different tenses. The findings revealed that passive voice occurred in academic textbooks with an overall frequency of 7.06% (of all conjugated verbs). The results also found significant differences between the academic genres (p (<) 0.05). In this particular corpus, passive voice occurred more in biology than in the other subjects. Therefore, the results of the study indicated a need to explicitly teach the basic be-passive voice to English language learners to all English learners, but teachers also need to be especially aware that certain university subjects (e.g., biology) use more passive voice verb forms than others.
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Date Issued: 2016
Identifier: CFE0006695, ucf:51929
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006695

Title: DEVELOPMENT OF A COMPACT BROADBAND OPTICAL PARAMETRIC OSCILLATOR FOR ULTRA-SENSITIVE MOLECULAR DETECTION.
Creator: Crystal, Sean O, Vodopyanov, Konstantin L., University of Central Florida
Abstract / Description: Every gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation...
Show moreEvery gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation patterned gallium-phosphide crystal. Periodically polled lithium niobate (PPLN), Gallium Arsenide (GaAs) and Gallium Phosphide are all crystals used to accomplish this task. GaP, in comparison to PPLN, has (i) a larger nonlinear coefficient, (ii) much deeper infrared transparency, and (iii) smaller group dispersion � to allow for achieving broad spectral coverage. GaP also has a larger band gap than GaAs; therefore it can still be pumped with a standard telecom C-band laser. An octave-wide spanning frequency comb system was achieved and the characterization of the system is presented. This system is specifically designed to be compact and portable for initial experimental testing in the applications of medical breath analysis and combustion gas investigation.
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Date Issued: 2017
Identifier: CFH2000274, ucf:45837
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000274

Title: THE EFFECTS OF RESISTANCE TRAINING FREQUENCY ON MUSCLE HYPERTOHY AND STRENGTH IN HEALTHY TRAINED INDIVIDUALS: LITERATURE REVIEW.
Creator: Boivin, Alexander C., Valdes, Anna, University of Central Florida
Abstract / Description: The purpose of this study is to determine the effects of increased resistance training frequency on strength and hypertrophy in trained individuals. Six Studies were deemed eligible based on the inclusion exclusion criteria. The inclusion criteria for this review were healthy trained individuals. "Trained" refers to over one year of resistance training experience. Exclusion Criteria were study's that examined either untrained or obese individuals as participants. The evidence indicates a dose...
Show moreThe purpose of this study is to determine the effects of increased resistance training frequency on strength and hypertrophy in trained individuals. Six Studies were deemed eligible based on the inclusion exclusion criteria. The inclusion criteria for this review were healthy trained individuals. "Trained" refers to over one year of resistance training experience. Exclusion Criteria were study's that examined either untrained or obese individuals as participants. The evidence indicates a dose-response trend in frequency. Resistance training each muscle group twice a week may be superior compared to once per week. Further more, resistance training each muscle group three times a week may enhance hypertrophy and strength adaptations even more compared to either once or twice a week. Recovery of the muscle may be reached in approximately 72 hours or 3 days. Mechanisms that may correlate to this phenomenon could be related to the more frequent elevations in muscle protein synthesis and physiological anabolic hormones. These results may help develop more specific guidelines in programming for intermediate to advanced athletes as well as lead way to more research on acute training variable manipulation.
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Date Issued: 2016
Identifier: CFH2000109, ucf:45953
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000109

Title: STABLE OPTICAL FREQUENCY COMB GENERATION AND APPLICATIONS IN ARBITRARY WAVEFORM GENERATION, SIGNAL PROCESSING AND OPTICAL DATA MINING.
Creator: Ozharar, Sarper, Delfyett, Peter, University of Central Florida
Abstract / Description: This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked...
Show moreThis thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the electronic waveform generator, and the RF carrier frequency is limited by the bandwidth of the photodetector. Similarly, using parabolic phase modulation together with time division multiplexing, RF chirp extension has been realized. Another application of the optical frequency combs studied in this thesis is real time data mining in a bit stream. A novel optoelectronic logic gate has been developed for this application and used to detect an 8 bit long target pattern. Also another approach based on orthogonal Hadamard codes have been proposed and explained in detail. Also novel intracavity modulation schemes have been investigated and applied for various applications such as a) improving rational harmonic modelocking for repetition rate multiplication and pulse to pulse amplitude equalization, b) frequency skewed pulse generation for ranging and c) intracavity active phase modulation in amplitude modulated modelocked lasers for supermode noise spur suppression and integrated jitter reduction. The thesis concludes with comments on the future work and next steps to improve some of the results presented in this work.
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Date Issued: 2008
Identifier: CFE0002388, ucf:47744
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002388

Title: NETWORK INTRUSION DETECTION: MONITORING, SIMULATION ANDVISUALIZATION.
Creator: Zhou, Mian, Lang, Sheau-Dong, University of Central Florida
Abstract / Description: This dissertation presents our work on network intrusion detection and intrusion sim- ulation. The work in intrusion detection consists of two different network anomaly-based approaches. The work in intrusion simulation introduces a model using explicit traffic gen- eration for the packet level traffic simulation. The process of anomaly detection is to first build profiles for the normal network activity and then mark any events or activities that deviate from the normal profiles as...
Show moreThis dissertation presents our work on network intrusion detection and intrusion sim- ulation. The work in intrusion detection consists of two different network anomaly-based approaches. The work in intrusion simulation introduces a model using explicit traffic gen- eration for the packet level traffic simulation. The process of anomaly detection is to first build profiles for the normal network activity and then mark any events or activities that deviate from the normal profiles as suspicious. Based on the different schemes of creating the normal activity profiles, we introduce two approaches for intrusion detection. The first one is a frequency-based approach which creates a normal frequency profile based on the periodical patterns existed in the time-series formed by the traffic. It aims at those attacks that are conducted by running pre-written scripts, which automate the process of attempting connections to various ports or sending packets with fabricated payloads, etc. The second approach builds the normal profile based on variations of connection-based behavior of each single computer. The deviations resulted from each individual computer are carried out by a weight assignment scheme and further used to build a weighted link graph representing the overall traffic abnormalities. The functionality of this system is of a distributed personal IDS system that also provides a centralized traffic analysis by graphical visualization. It provides a finer control over the internal network by focusing on connection-based behavior of each single computer. For network intrusion simulation, we explore an alternative method for network traffic simulation using explicit traffic generation. In particular, we build a model to replay the standard DARPA traffic data or the traffic data captured from a real environment. The replayed traffic data is mixed with the attacks, such as DOS and Probe attack, which can create apparent abnormal traffic flow patterns. With the explicit traffic generation, every packet that has ever been sent by the victim and attacker is formed in the simulation model and travels around strictly following the criteria of time and path that extracted from the real scenario. Thus, the model provides a promising aid in the study of intrusion detection techniques.
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Date Issued: 2005
Identifier: CFE0000679, ucf:46484
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000679

Title: THE EFFECT OF HOT CARRIER STRESS ON LOW NOISE AMPLIFIER RADIO FREQUENCY PERFORMANCE UNDER WEAK AND STRONG INVERSION.
Creator: Shen, Lin, Yuan, Jiann, University of Central Florida
Abstract / Description: This thesis work is mainly focused on studying RF performance degradation of a low noise amplifier (LNA) circuit due to hot carrier effect (HCE) in both the weak and strong inversion regions. Since the figures of merit for the RF circuit characterization are gain, noise figure, input, and output matching, the LNA RF performance drift is evaluated in a Cadence SpectreRF simulator subject to these features. This thesis presents hot carrier induced degradation results of an LNA to show that the...
Show moreThis thesis work is mainly focused on studying RF performance degradation of a low noise amplifier (LNA) circuit due to hot carrier effect (HCE) in both the weak and strong inversion regions. Since the figures of merit for the RF circuit characterization are gain, noise figure, input, and output matching, the LNA RF performance drift is evaluated in a Cadence SpectreRF simulator subject to these features. This thesis presents hot carrier induced degradation results of an LNA to show that the HCE phenomenon is one of the serious reliability issues in the aggressively scaled RF CMOS design, especially for long-term operation of these devices. The predicted degradation from simulation results can be used design reliable CMOS RF circuits.
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Date Issued: 2006
Identifier: CFE0000952, ucf:46763
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000952

Title: NOVEL COMPLEX ADAPTIVE SIGNAL PROCESSING TECHNIQUES EMPLOYING OPTIMALLY DERIVED TIME-VARYING CONVERGENCE FACTORS WITH APPLICATIONS IN DIGITAL SIGNAL PROCESSING AND WIRELESS COMMUNICATIONS.
Creator: Ranganathan, Raghuram, Mikhael, Wasfy, University of Central Florida
Abstract / Description: In digital signal processing in general, and wireless communications in particular, the increased usage of complex signal representations, and spectrally efficient complex modulation schemes such as QPSK and QAM has necessitated the need for efficient and fast-converging complex digital signal processing techniques. In this research, novel complex adaptive digital signal processing techniques are presented, which derive optimal convergence factors or step sizes for adjusting the adaptive...
Show moreIn digital signal processing in general, and wireless communications in particular, the increased usage of complex signal representations, and spectrally efficient complex modulation schemes such as QPSK and QAM has necessitated the need for efficient and fast-converging complex digital signal processing techniques. In this research, novel complex adaptive digital signal processing techniques are presented, which derive optimal convergence factors or step sizes for adjusting the adaptive system coefficients at each iteration. In addition, the real and imaginary components of the complex signal and complex adaptive filter coefficients are treated as separate entities, and are independently updated. As a result, the developed methods efficiently utilize the degrees of freedom of the adaptive system, thereby exhibiting improved convergence characteristics, even in dynamic environments. In wireless communications, acceptable co-channel, adjacent channel, and image interference rejection is often one of the most critical requirements for a receiver. In this regard, the fixed-point complex Independent Component Analysis (ICA) algorithm, called Complex FastICA, has been previously applied to realize digital blind interference suppression in stationary or slow fading environments. However, under dynamic flat fading channel conditions frequently encountered in practice, the performance of the Complex FastICA is significantly degraded. In this dissertation, novel complex block adaptive ICA algorithms employing optimal convergence factors are presented, which exhibit superior convergence speed and accuracy in time-varying flat fading channels, as compared to the Complex FastICA algorithm. The proposed algorithms are called Complex IA-ICA, Complex OBA-ICA, and Complex CBC-ICA. For adaptive filtering applications, the Complex Least Mean Square algorithm (Complex LMS) has been widely used in both block and sequential form, due to its computational simplicity. However, the main drawback of the Complex LMS algorithm is its slow convergence and dependence on the choice of the convergence factor. In this research, novel block and sequential based algorithms for complex adaptive digital filtering are presented, which overcome the inherent limitations of the existing Complex LMS. The block adaptive algorithms are called Complex OBA-LMS and Complex OBAI-LMS, and their sequential versions are named Complex HA-LMS and Complex IA-LMS, respectively. The performance of the developed techniques is tested in various adaptive filtering applications, such as channel estimation, and adaptive beamforming. The combination of Orthogonal Frequency Division Multiplexing (OFDM) and the Multiple-Input-Multiple-Output (MIMO) technique is being increasingly employed for broadband wireless systems operating in frequency selective channels. However, MIMO-OFDM systems are extremely sensitive to Intercarrier Interference (ICI), caused by Carrier Frequency Offset (CFO) between local oscillators in the transmitter and the receiver. This results in crosstalk between the various OFDM subcarriers resulting in severe deterioration in performance. In order to mitigate this problem, the previously proposed Complex OBA-ICA algorithm is employed to recover user signals in the presence of ICI and channel induced mixing. The effectiveness of the Complex OBA-ICA method in performing ICI mitigation and signal separation is tested for various values of CFO, rate of channel variation, and Signal to Noise Ratio (SNR).
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Date Issued: 2008
Identifier: CFE0002431, ucf:47765
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002431

Title: Point Cloud Technology for Analysis of Existing Structures.
Creator: Cano, Jacob, Catbas, Necati, Apostolakis, Georgios, Zaurin, Ricardo, Walters, Lori, University of Central Florida
Abstract / Description: For this thesis, a study was completed on two different structures on the UCF Orlando campus through the use of both structural plans and point cloud technology. The results sought to understand the viability of point cloud technology as an accurate tool for the static and dynamic modal analysis of existing structures. For static analysis, a portion of the framing of Spectrum Stadium was rendered, modeled, analyzed and compared to a previous case study. The results emphasized how different...
Show moreFor this thesis, a study was completed on two different structures on the UCF Orlando campus through the use of both structural plans and point cloud technology. The results sought to understand the viability of point cloud technology as an accurate tool for the static and dynamic modal analysis of existing structures. For static analysis, a portion of the framing of Spectrum Stadium was rendered, modeled, analyzed and compared to a previous case study. The results emphasized how different users can render dissimilar member sizes and lengths due to human judgment on point cloud visuals. The study also found that structural plans cannot always be relied upon as the most accurate source for analysis as the new point cloud produced more accurate results than the structural plans when compared to the control model. For the pedestrian bridge, the structure was scanned, rendered and modeled for both static and dynamic modal analysis. The point cloud produced from scanning the bridge was modified twice in order to have three distinct point clouds with varying densities: fine, medium and coarse. These three cases were compared to structural plans in a static analysis. The fine point cloud produced the most accurate displacement results with an accuracy above 96%. The data sources were also compared to experimental data under dynamic modal analysis to discover how lessening the density of point clouds affect the accuracy of results. The analysis showed that point cloud technology can give you an accuracy of 88% and above for frequency while also producing MAC values exceeding 0.9 consistently. Also, changes in density were found to change the accuracy of results but the numeric values stayed within close proximity by not differing more than 10%. This thesis shines a light on the accuracy point cloud technology can ascertain and the potential it has within engineering.
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Date Issued: 2019
Identifier: CFE0007438, ucf:52724
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007438

Title: Broadband Mid-infrared Frequency Combs Generated via Frequency Division.
Creator: Ru, Qitian, Vodopyanov, Konstantin, Fathpour, Sasan, Wu, Shintson, Peale, Robert, University of Central Florida
Abstract / Description: Frequency combs have revolutionized metrology and demonstrated numerous applications in science and technology. Combs operating in the mid-infrared region could be beneficial for molecular spectroscopy for several reasons. First, numerous molecules have their spectroscopic signatures in this region. Furthermore, the atmospheric window (3-5(&)#181;m and 8-14(&)#181;m) is located here. Additionally, a mid-infrared frequency comb could be employed as a diagnostic tool for the many components of...
Show moreFrequency combs have revolutionized metrology and demonstrated numerous applications in science and technology. Combs operating in the mid-infrared region could be beneficial for molecular spectroscopy for several reasons. First, numerous molecules have their spectroscopic signatures in this region. Furthermore, the atmospheric window (3-5(&)#181;m and 8-14(&)#181;m) is located here. Additionally, a mid-infrared frequency comb could be employed as a diagnostic tool for the many components of human breath, as well as for detection of harmful gases and contaminants in the atmosphere. In this thesis, I used synchronously pumped subharmonic optical parametric oscillators (OPOs) operating at degeneracy to produce ultra-broadband outputs near half of the pump laser frequency. One attractive property of the subharmonic OPOs is that the signal/idler waves of the OPO are frequency- and phase-locked to the pump frequency comb. We explored three new nonlinear materials in the subharmonic OPO and demonstrated a broadband spectrum for mid-infrared frequency comb generation. (1) Orientation-patterned (OP) gallium arsenide (GaAs) was selected as the first material because it has high nonlinearity. We found that the OP-GaAs based OPO yielded an approximately two-octave wide spectrum (2.8(-)11(&)#181;m). (2) Gallium phosphide (GaP) has near zero group velocity dispersion (GVD) at 4.7 (&)#181;m and a large bandgap. The OP-GaP OPO yielded a spectrum of more than two octaves (3(-)12.5(&)#181;m). Also, because of the large bandgap, GaP is suitable for telecom 1.56-(&)#181;m pumping, having the advantage of much smaller GVD than in periodically-poled-lithium-niobite (PPLN). The telecom laser (1.56(&)#181;m) pumped OP-GaP OPO was demonstrated with more than one octave wide spectrum. (3) Finally, we explored the phenomenon of random phase matching in the zinc selenide (ZnSe) polycrystalline material. The first random phase matched OPO was demonstrated with more than one octave spectrum (3.1(-) 9(&)#181;m), which is also the first OPO based on ZnSe.
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Date Issued: 2019
Identifier: CFE0007718, ucf:52430
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007718

Title: INNOVATIVE POLLUTANT LOAD MONITORING.
Creator: Gurr, Eric, Nnadi, Fidelia, University of Central Florida
Abstract / Description: Modern streamflow measuring equipment, water quality sampling techniques and a better understanding of pollutant washoff are continuously being developed as today's society is in critical need of improving water management, minimizing developmental impacts and preventing environmental hazards. In particular, the study of the spatial, temporal and volumetric characteristics of annual pollutant loading caused by variations in precipitation, land use and other anthropogenic factors is of great...
Show moreModern streamflow measuring equipment, water quality sampling techniques and a better understanding of pollutant washoff are continuously being developed as today's society is in critical need of improving water management, minimizing developmental impacts and preventing environmental hazards. In particular, the study of the spatial, temporal and volumetric characteristics of annual pollutant loading caused by variations in precipitation, land use and other anthropogenic factors is of great significance due to their relation to future global water demands. The research presented here falls in three parts. In the first part of the dissertation, an acoustical doppler velocity profiler installed in a submerged concrete channel is proposed to continually measure the annual fluctuation in streamflow levels down to dry channel conditions. The tailwater influenced, intermittent streamflow conditions for the City of Kissimmee, Florida were selected for the evaluation of this approach under a 3-year study from 2006 to 2008. The performance of these concrete channels were systematically evaluated by comparisons with established field measurement techniques over various stream configurations and flow conditions. The second part of this research investigates the dynamics of flood wave detection with respect to enabling an automatic water quality sampler to start collecting samples. The main focus was on the accurate detection of flood waves in the absence of rainfall and the presence of fluctuating baseflows and stream stages. In the 3-year study, it was shown that a dual parameter trigger, utilizing independent measuring equipment, resulted in accurate flood wave detection with minimal false triggering of the autosampler. In addition, an incremental or percent deviation from a moving average of stage or flow proved to be a more consistent indicator for the presence of a flood wave. In the third part of this work, the frequency of water quality sampling and the associated level of detail for sampling of rainfall events were investigated with respect to accurately depicting annual pollutant loads. It was found that the seasonal variations in baseflow pollutant loads are not accurately represented by current 4-quarter grab sampling. Also, significant pollutant loading within rainfall events may not be captured by only performing grab sampling during baseflow conditions. In addition, although increased pollutant concentrations were observed within the initial 30 minutes of the flood wave, their actual loadings did not represent a significant impact on the annual pollutant loads. A bi-weekly grab sampling frequency was found to be adequate in many cases to depict the annual pollutant loads, but depending upon the targeted constituent and particular streamflow condition, rainfall event sampling might also be necessary. The results of this research complemented with other studies will promote better understanding of intermittent streamflows, accurate flood wave detection, and assessment of annual pollutant loads to our nation's waterbodies.
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Date Issued: 2011
Identifier: CFE0004002, ucf:49159
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004002

Title: Wavelength scale resonant structures for integrated photonic applications.
Creator: Weed, Matthew, Schoenfeld, Winston, Moharam, M., Likamwa, Patrick, Delfyett, Peter, Leuenberger, Michael, University of Central Florida
Abstract / Description: An approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled...
Show moreAn approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled cavity systems offer the designer slow light propagation which increases photon lifetime, reduces size limitations toward on-chip integration, and offers enhanced light-matter interaction. A unique resonant structure explained by various numerical models enables comb-like resonant clusters in systems that otherwise have no such regular resonant landscape (e.g. photonic crystal cavities). Through design, simulation, fabrication and test, the work presented here is a thorough validation for the future potential of coupled-resonator filters in frequency comb laser sources.
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Date Issued: 2013
Identifier: CFE0004957, ucf:49568
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004957

Title: Error Rates in Narrow-band Digital FM Systems Operating Various Interference Environments.
Creator: Rodriguez, Arthur M., Mathews, B.E., Engineering
Abstract / Description: Florida Technological University College of Engineering Thesis
Date Issued: 1975
Identifier: CFR0004778, ucf:52971
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFR0004778

Title: HJB Equation and Statistical Arbitrage applied to High Frequency Trading.
Creator: Park, Yonggi, Yong, Jiongmin, Swanson, Jason, Richardson, Gary, Shuai, Zhisheng, University of Central Florida
Abstract / Description: In this thesis we investigate some properties of market making and statistical arbitrage applied to High Frequency Trading (HFT). Using the Hamilton-Jacobi-Bellman(HJB) model developed by Guilbaud, Fabien and Pham, Huyen in 2012, we studied how market making works to obtain optimal strategy during limit order and market order. Also we develop the best investment strategy through Moving Average, Exponential Moving Average, Relative Strength Index, Sharpe Ratio.
Date Issued: 2013
Identifier: CFE0004907, ucf:49628
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004907

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