Hyper-wideband communications represent the next frontier in spread spectrum RF systems with an excess of 10 GHz instantaneous bandwidth. In this thesis, an end-to-end physical layer link is implemented featuring 16k-OFDM with a 4 GHz-wide channel centered at 9 GHz. No a priori channel state information is assumed; channel information is derived from the preamble and comb pilot structure. Due to the unique expansive spectral properties, the channel estimator is primarily composed of least squares channel estimates combined with a robust support vector statistical learning approach using autonomously selected parameters. The system’s performance is demonstrated through indoor wireless experiments, including line-of-sight and near-line-of-sight links. Moreover, it is shown that the support vector approach performs superior to linear and cubic spline inter/extrapolation of the least squares channel estimates.

Data generated by complex, computational models can provide highly accurate predictions of hydrological and hydrodynamic data in multiple dimensions. Unfortunately, however, for large data sets, running these models is often timeconsuming and computationally expensive. Thus, finding a way to reduce the running time of these models, while still producing comparable results, is of notable interest. The Inference Engine is a proposed system for doing just this. It takes previously generated model data and uses them to predict additional data. Its performance, both accuracy and running time, has been compared to the performance of the actual models, in increasingly difficult data prediction tasks, and it is able, with sufficient accuracy, to quickly predict unknown model data.

This study seeks to investigate weather-related flight delay trends at 13 United States airports. Flight delay data were collected from 2004-2019 and normalized by airport operations data. Using Support Vector Regression (SVR), visual trends were identified. Further analysis was conducted by comparing all four meteorological seasons through computing 95% bootstrap confidence intervals on their means. Finally, precipitation and snowfall data were correlated with normalized delays to investigate how they are related. This study found that the season with the highest normalized delay values is heavily dependent upon location. Most airports saw a decrease in the SVR line at some point since 2004, but have since leveled off. It was also discovered that while precipitation trends are not changing drastically, delay variability has decreased at many airports in the last 10 years, which may be indicative of more effective mitigation strategies.

This thesis studies the problem of frequentist model averaging over a set of multiple $\epsilon$-support vector regression (SVR) models, where the support vector machine (SVM) algorithm was extended to function estimation involving continuous targets, instead of categorical ones. By assigning weights to a set of candidate models instead of selecting the least misspecified one, model averaging presents a strong alternative to model selection for tackling model uncertainty. Not only do we describe the construction of smoothed BIC/AIC model averaging weights, but we also propose a Mallows model averaging procedure which selects model weights by minimizing Mallows' criterion. We conduct two studies where the set of candidate models can either include or not include the true model by making use of simulated random samples obtained from different data-generating processes of analytic form. In terms of mean squared error, we demonstrate that our proposed method outperforms other model averaging and model selection methods that were tested, and the gain is more substantial for smaller sample sizes with larger signal-to-noise ratios. / Thesis / Master of Science (MSc)

Machine learning is emerging as a powerful tool to data science and is being applied in almost all subjects. In many applications, the number of features is com- parable to the number of samples, and both grow large. This setting is usually named the high-dimensional regime. In this regime, new challenges arise when it comes to the application of machine learning. In this work, we conduct a high-dimensional performance analysis of some popular classification and regression techniques. In a first part, discriminant analysis classifiers are considered. A major challenge towards the use of these classifiers in practice is that they depend on the inverse of covariance matrices that need to be estimated from training data. Several estimators for the inverse of the covariance matrices can be used. The most common ones are estimators based on the regularization approach. In this thesis, we propose new estimators that are shown to yield better performance. The main principle of our proposed approach is the design of an optimized inverse covariance matrix estimator based on the assumption that the covariance matrix is a low-rank perturbation of a scaled identity matrix. We show that not only the proposed classifiers are easier to implement but also, outperform the classical regularization-based discriminant analysis classifiers. In a second part, we carry out a high-dimensional statistical analysis of linear support vector regression. Under some plausible assumptions on the statistical dis- tribution of the data, we characterize the feasibility condition for the hard support vector regression and, when feasible, derive an asymptotic approximation for its risk. Similarly, we study the test risk for the soft support vector regression as a function of its parameters. The analysis is then extended to the case of kernel support vector regression under generalized linear models assumption. Based on our analysis, we illustrate that adding more samples may be harmful to the test performance of these regression algorithms, while it is always beneficial when the parameters are optimally selected. Our results pave the way to understand the effect of the underlying hyper- parameters and provide insights on how to optimally choose the kernel function.

Rotylenchulus reniformis is a nematode species affecting the cotton crop and quickly spreading throughout the southeastern United States. Effective use of nematicides at a variable rate is the only economic counter measure. It requires the intraield variable nematode population, which in turn depends on the collection of soil samples from the field and analyzing them in the laboratory. This process is economically prohibitive. Hence estimating the nematode infestation on the cotton crop using remote sensing and machine learning techniques which are cost and time effective is the motivation for this study. In the current research, the concept of multi-temporal remote sensing has been implemented in order to design a robust and generalized Nematode detection regression model. Finally, a user friendly web-service is created which is gives trustworthy results for the given input data and thereby reducing the nematode infestation in the crop and their expenses on nematicides.

Denna studie har syftet att undersöka sambandet mellan luftföroreningar och olika fordonsvariabler, såsom årsmodell, bränsletyp och fordonstyp, på Hornsgatan i Stockholm. Studien avser att besvara vilka faktorer som har störst inverkan på luftkvaliteten. Utförandet baseras på maskininlärningsalgoritmerna Random Forest och Support Vector Regression, vilka jämförs utifrån R² och RMSE. Modellerna skapade med Random Forest överträffar Support Vector Regression för de olika luftföroreningarna. Den modell som presterade bäst var modellen för kolmonoxid vilken hade ett R²-värde på 99.7%. Den modell som gav prediktioner med lägst R²-värde, 68.4%, var modellen för kvävedioxid. Överlag var resultaten goda i relation till tidigare studier. Utifrån modellerna diskuteras variablers inverkan och olika åtgärder som kan införas i Stockholm Stad och på Hornsgatan för att förbättra luftkvaliteten. / This study aims to investigate the relationship between multiple air pollution and different vehicle variables, such as vehicle year, fuel type and vehicle type, on Hornsgatan in Stockholm. The study intends to answer which factors have the greatest impact on air quality. The implementation is based on the two machine learning algorithms Random Forest and Support Vector Regression, which are compared based on R² and RMSE. The models created with Random Forest outperform Support Vector Regression for the various air pollutants. The best performing model was the carbon monoxide model which had an R²-value of 99.7%. The model that gave predictions with the lowest R²-value, 68.4%, was the model for nitrogen dioxide. Overall, the results were good in relation to previous studies. With regards to these models, the impact of variables and different measures that can be introduced in the City of Stockholm and on Hornsgatan to improve air quality are discussed.

Denna studie har syftet att undersöka sambandet mellan luftföroreningar och olika fordonsvariabler, såsom årsmodell, bränsletyp och fordonstyp, på Hornsgatan i Stockholm. Studien avser att besvara vilka faktorer som har störst inverkan på luftkvaliteten. Utförandet baseras på maskininlärningsalgoritmerna Random Forest och Support Vector Regression, vilka jämförs utifrån R^2 och RMSE. Modellerna skapade med Random Forest överträffar Support Vector Regression för de olika luftföroreningarna. Den modell som presterade bäst var modellen för kolmonoxid vilken hade ett R^2-värde på 99.7%. Den modell som gav prediktioner med lägst R^2-värde, 68.4%, var modellen för kvävedioxid. Överlag var resultaten goda i relation till tidigare studier. Utifrån modellerna diskuteras variablers inverkan och olika åtgärder som kan införas i Stockholm Stad och på Hornsgatan för att förbättra luftkvaliteten. / This study aims to investigate the relationship between multiple air pollution and different vehicle variables, such as vehicle year, fuel type and vehicle type, on Hornsgatan in Stockholm. The study intends to answer which factors have the greatest impact on air quality. The implementation is based on the two machine learning algorithms Random Forest and Support Vector Regression, which are compared based on R^2 and RMSE. The models created with Random Forest outperform Support Vector Regression for the various air pollutants. The best performing model was the carbon monoxide model which had an R^2-value of 99.7%. The model that gave predictions with the lowest R^2-value, 68.4%, was the model for nitrogen dioxide. Overall, the results were good in relation to previous studies. With regards to these models, the impact of variables and different measures that can be introduced in the City of Stockholm and on Hornsgatan to improve air quality are discussed.

Antibiotic resistant bacteria, a growing health crisis, arise due to antibiotic overuse and misuse. Resistant infections endanger the lives of patients and are financially burdensome. Aggregate antimicrobial susceptibility reports, called antibiograms, are critical for tracking antibiotic susceptibility and evaluating the likelihood of the effectiveness of different antibiotics to treat an infection prior to the availability of patient specific susceptibility data. This research leverages the Massachusetts Statewide Antibiogram database, a rich dataset composed of antibiograms for $754$ antibiotic-bacteria pairs collected by the Massachusetts Department of Public Health from $2002$ to $2016$. However, these antibiograms are at least a year old, meaning antibiotics are prescribed based on outdated data which unnecessarily furthers resistance. Our objective is to employ data science techniques on these antibiograms to assist in developing more responsible antibiotic prescription practices. First, we use model selectors with regression-based techniques to forecast the current antimicrobial resistance. Next, we develop an assistant to immediately identify clinically and statistically significant changes in antimicrobial resistance between years once the most recent year of antibiograms are collected. Lastly, we use k-means clustering on resistance trends to detect antibiotic-bacteria pairs with resistance trends for which forecasting will not be effective. These three strategies can be implemented to guide more responsible antibiotic prescription practices and thus reduce unnecessary increases in antibiotic resistance.

Antibiotic resistant bacteria, a growing health crisis, arise due to antibiotic overuse and misuse. Resistant infections endanger the lives of patients and are financially burdensome. Aggregate antimicrobial susceptibility reports, called antibiograms, are critical for tracking antibiotic susceptibility and evaluating the likelihood of the effectiveness of different antibiotics to treat an infection prior to the availability of patient specific susceptibility data. This research leverages the Massachusetts Statewide Antibiogram database, a rich dataset composed of antibiograms for $754$ antibiotic-bacteria pairs collected by the Massachusetts Department of Public Health from $2002$ to $2016$. However, these antibiograms are at least a year old, meaning antibiotics are prescribed based on outdated data which unnecessarily furthers resistance. Our objective is to employ data science techniques on these antibiograms to assist in developing more responsible antibiotic prescription practices. First, we use model selectors with regression-based techniques to forecast the current antimicrobial resistance. Next, we develop an assistant to immediately identify clinically and statistically significant changes in antimicrobial resistance between years once the most recent year of antibiograms are collected. Lastly, we use k-means clustering on resistance trends to detect antibiotic-bacteria pairs with resistance trends for which forecasting will not be effective. These three strategies can be implemented to guide more responsible antibiotic prescription practices and thus reduce unnecessary increases in antibiotic resistance.