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MODELING AND CHARACTERIZATIONS OF NEW NOTIONS IN LIFE TESTING WITH STATISTICAL APPLICATIONS
Title
MODELING AND CHARACTERIZATIONS OF NEW NOTIONS IN LIFE TESTING WITH STATISTICAL APPLICATIONS.
Creator
Sepehrifar, Mohammad, Ahmad, Ibrahim, University of Central Florida
Abstract / Description
Knowing the class to which a life distribution belongs gives us an idea about the aging of the device or system the life distribution represents, and enables us to compare the aging properties of different systems. This research intends to establish several new nonparametric classes of life distributions defined by the concept of inactivity time of a unit with a guaranteed minimum life length. These classes play an important role in the study of reliability theory, survival analysis,...
Show moreKnowing the class to which a life distribution belongs gives us an idea about the aging of the device or system the life distribution represents, and enables us to compare the aging properties of different systems. This research intends to establish several new nonparametric classes of life distributions defined by the concept of inactivity time of a unit with a guaranteed minimum life length. These classes play an important role in the study of reliability theory, survival analysis, maintenance policies, economics, actuarial sciences and many other applied areas.
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Date Issued
2006
Identifier
CFE0001316, ucf:47030
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001316
SMOOTHING PARAMETER SELECTION IN NONPARAMETRIC FUNCTIONAL ESTIMATION
Title
SMOOTHING PARAMETER SELECTION IN NONPARAMETRIC FUNCTIONAL ESTIMATION.
Creator
Amezziane, Mohamed, Ahmad, Ibrahim, University of Central Florida
Abstract / Description
This study intends to build up new techniques for how to obtain completely data-driven choices of the smoothing parameter in functional estimation, within the confines of minimal assumptions. The focus of the study will be within the framework of the estimation of the distribution function, the density function and their multivariable extensions along with some of their functionals such as the location and the integrated squared derivatives.
Date Issued
2004
Identifier
CFE0000307, ucf:46314
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000307
LOW NOISE, NARROW OPTICAL LINEWIDTH SEMICONDUCTOR-BASED OPTICAL COMB SOURCE AND LOW NOISE RF SIGNAL GENERATION
Title
LOW NOISE, NARROW OPTICAL LINEWIDTH SEMICONDUCTOR-BASED OPTICAL COMB SOURCE AND LOW NOISE RF SIGNAL GENERATION.
Creator
Ozdur, Ibrahim, Delfyett, Peter, University of Central Florida
Abstract / Description
Recently optical frequency combs and low noise RF tones are drawing increased attention due to applications in spectroscopy, metrology, arbitrary waveform generation, optical signal processing etc. This thesis focuses on the generation of low noise RF tones and stabilized optical frequency combs. The optical frequency combs are generated by a semiconductor based external cavity mode-locked laser with a high finesse intracavity etalon. In order to get the lowest noise and broadest bandwidth...
Show moreRecently optical frequency combs and low noise RF tones are drawing increased attention due to applications in spectroscopy, metrology, arbitrary waveform generation, optical signal processing etc. This thesis focuses on the generation of low noise RF tones and stabilized optical frequency combs. The optical frequency combs are generated by a semiconductor based external cavity mode-locked laser with a high finesse intracavity etalon. In order to get the lowest noise and broadest bandwidth from the mode-locked laser, it is critical to know the free spectral range (FSR) of the etalon precisely. First the etalon FSR is measured by using the modified Pound-Drever-Hall (PDH) based method and obtained a resolution of 1 part in 106, which is 2 order of magnitude better than the standard PDH based method. After optimizing the cavity length, RF driving frequency and PDH cavity locking point, the mode-locked laser had an integrated timing jitter of 3 fs (1 Hz- 100 MHz) which is, to the best of our knowledge, the lowest jitter ever reported from a semiconductor based multigigahertz comb source. The mode-locked laser produces ~ 100 comb lines with 10 GHz spacing, a linewidth of ~500 Hz and 75 dB optical signal-to-noise ratio. The same system can also be driven as a regeneratively mode-locked laser with greatly improved noise performance. Another way of generating a low noise RF tone is using an opto-electronic oscillator which uses an optical cavity as a high Q element. Due to the harmonic nature of OEOs, a mode selection element is necessary. Standard OEOs use an RF filter having drawbacks such as broad pass band, high loss, and high thermal noise. In our work, a novel optoelectronic scheme which uses an optical filter (Fabry-Perot etalon) as the mode filter instead of an RF filter is demonstrated. This method has the advantage of having ultra-narrow filtering bandwidths ( ~ 10 kHz for a 10 GHz FSR and 106 finesse) and an extremely low noise RF signal. Experimental demonstration of the proposed method resulted in a 5-10 dB decrease of the OEO noise compared to the conventional OEO setup. Also, by modifying the etalon-based OEO, and using single side band modulation, an optically tunable optoelectronic oscillator is achieved with 10-20 dB lower noise than dual side band modulation. Noise properties of the OEO as a function of optical frequency detuning is also analyzed theoretically and the results are in agreement with experimental results.
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Date Issued
2011
Identifier
CFE0003573, ucf:48917
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003573
Improvement of Data-Intensive Applications Running on Cloud Computing Clusters
Title
Improvement of Data-Intensive Applications Running on Cloud Computing Clusters.
Creator
Ibrahim, Ibrahim, Bassiouni, Mostafa, Lin, Mingjie, Zhou, Qun, Ewetz, Rickard, Garibay, Ivan, University of Central Florida
Abstract / Description
MapReduce, designed by Google, is widely used as the most popular distributed programmingmodel in cloud environments. Hadoop, an open-source implementation of MapReduce, is a data management framework on large cluster of commodity machines to handle data-intensive applications. Many famous enterprises including Facebook, Twitter, and Adobehave been using Hadoop for their data-intensive processing needs. Task stragglers in MapReduce jobs dramatically impede job execution on massive datasets in...
Show moreMapReduce, designed by Google, is widely used as the most popular distributed programmingmodel in cloud environments. Hadoop, an open-source implementation of MapReduce, is a data management framework on large cluster of commodity machines to handle data-intensive applications. Many famous enterprises including Facebook, Twitter, and Adobehave been using Hadoop for their data-intensive processing needs. Task stragglers in MapReduce jobs dramatically impede job execution on massive datasets in cloud computing systems. This impedance is due to the uneven distribution of input data and computation load among cluster nodes, heterogeneous data nodes, data skew in reduce phase, resource contention situations, and network configurations. All these reasons may cause delay failure and the violation of job completion time. One of the key issues that can significantly affect the performance of cloud computing is the computation load balancing among cluster nodes. Replica placement in Hadoop distributed file system plays a significant role in data availability and the balanced utilization of clusters. In the current replica placement policy (RPP) of Hadoop distributed file system (HDFS), the replicas of data blocks cannot be evenly distributed across cluster's nodes. The current HDFS must rely on a load balancing utility for balancing the distribution of replicas, which results in extra overhead for time and resources. This dissertation addresses data load balancing problem and presents an innovative replica placement policy for HDFS. It can perfectly balance the data load among cluster's nodes. The heterogeneity of cluster nodes exacerbates the issue of computational load balancing; therefore, another replica placement algorithm has been proposed in this dissertation for heterogeneous cluster environments. The timing of identifying the straggler map task is very important for straggler mitigation in data-intensive cloud computing. To mitigate the straggler map task, Present progress and Feedback based Speculative Execution (PFSE) algorithm has been proposed in this dissertation. PFSE is a new straggler identification scheme to identify the straggler map tasks based on the feedback information received from completed tasks beside the progress of the current running task. Straggler reduce task aggravates the violation of MapReduce job completion time. Straggler reduce task is typically the result of bad data partitioning during the reduce phase. The Hash partitioner employed by Hadoop may cause intermediate data skew, which results in straggler reduce task. In this dissertation a new partitioning scheme, named Balanced Data Clusters Partitioner (BDCP), is proposed to mitigate straggler reduce tasks. BDCP is based on sampling of input data and feedback information about the current processing task. BDCP can assist in straggler mitigation during the reduce phase and minimize the job completion time in MapReduce jobs. The results of extensive experiments corroborate that the algorithms and policies proposed in this dissertation can improve the performance of data-intensive applications running on cloud platforms.
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Date Issued
2019
Identifier
CFE0007818, ucf:52804
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007818
Unicondylar Knee Arthroplasty in the Inpatient vs Outpatient Setting: Impact on Process Time, Quality Outcomes, and Patient Satisfaction
Title
Unicondylar Knee Arthroplasty in the Inpatient vs Outpatient Setting: Impact on Process Time, Quality Outcomes, and Patient Satisfaction.
Creator
Zeini, Ibrahim, Ramirez, Bernardo, Noblin, Alice, Liu, Albert Xinliang, Sivo, Stephen, University of Central Florida
Abstract / Description
The implications of rising healthcare expenditures are of great concern nationally and internationally. Performing procedures in the outpatient setting can be one solution to this crisis. However, there is a lack of research on systematic approaches for transitioning procedures to the outpatient setting. Unicondylar knee arthroplasty (UKA) presents an opportunity, as it is already in the early stages of transitioning to the outpatient setting. The key step in facilitating an effective...
Show moreThe implications of rising healthcare expenditures are of great concern nationally and internationally. Performing procedures in the outpatient setting can be one solution to this crisis. However, there is a lack of research on systematic approaches for transitioning procedures to the outpatient setting. Unicondylar knee arthroplasty (UKA) presents an opportunity, as it is already in the early stages of transitioning to the outpatient setting. The key step in facilitating an effective transition to the outpatient setting is comparing outpatient UKAs with inpatient UKAs with a focus on process time, quality outcomes, and patient satisfaction. This study retrospectively compares 400 UKA patients in the outpatient setting with 675 UKA patients in the inpatient setting. The primary analytical tools for this study are Ordinary Least Squares Regression, Logistic Regression, and Ordinal Regression adjusting for comorbidity, social history, demographics, and surgery related characteristics. Outpatient UKAs outperformed inpatient UKAs across 11 of 18 variables analyzed. Process Time will be less for outpatient UKAs in all phases with the exception of Surgery Breakdown Time. The risk-adjusted quality outcomes of UKAs in the outpatient setting were better across Non-Surgery Related Complications, Follow-Up Pain, and Follow-Up Functional Range of Motion Limitation. Patient Satisfaction was higher for outpatient UKAs. There was a lack of consistent and appropriate information to conduct a substantial statistical analysis of the costs. These findings point towards outpatient UKAs being a viable option in the future. This research serves as a platform to launch a system-wide effort of transitioning procedures to the outpatient setting across different specialties.
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Date Issued
2015
Identifier
CFE0006427, ucf:51489
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006427