2000-2019

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https://hdl.handle.net/10217/100538

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Open Access
A comparison of tri-polar concentric ring electrodes to disc electrodes for decoding real and imaginary finger movements
(Colorado State University. Libraries, 2019) Alzahrani, Saleh Ibrahim, author; Anderson, Charles W., advisor; Vigh, Jozsef, committee member; Rojas, Don, committee member; Abdel-Ghany, Salah, committee member
The electroencephalogram (EEG) is broadly used for diagnosis of brain diseases and research of brain activities. Although the EEG provides a good temporal resolution, it suffers from poor spatial resolution due to the blurring effects of volume conduction and signal-to-noise ratio. Many efforts have been devoted to the development of novel methods that can increase the EEG spatial resolution. The surface Laplacian, which is the second derivative of the surface potential, has been applied to EEG to improve the spatial resolution. Tri-polar concentric ring electrodes (TCREs) have been shown to estimate the surface Laplacian automatically with better spatial resolution than conventional disc electrodes. The aim of this research is to study how well the TCREs can be used to acquire EEG signals to decode real and imaginary finger movements. These EEG signals will be then translated into finger movements commands. We also compare the feasibility of discriminating finger movements from one hand using EEG recorded from TCREs and conventional disc electrodes. Furthermore, we evaluated two movement-related features, temporal EEG data and spectral features, in discriminating individual finger from one hand using non-invasive EEG. To do so, movement-related potentials (MRPs) are measured and analyzed from four TCREs and conventional disc electrodes while 13 subjects performed either motor execution or motor imagery of individual finger movements. The tri-polar-EEG (tEEG) and conventional EEG (cEEG) were recorded from electrodes placed according to the 10-20 International Electrode Positioning System over the motor cortex. Our results show that the TCREs achieved higher spatial resolution than conventional disc electrodes. Moreover, the results show that signals from TCREs generated higher decoding accuracy compared to signals from conventional disc electrodes. The average decoding accuracy of five-class classification for all subjects was of 70.04 ± 7.68% when we used temporal EEG data as feature and classified it using Artificial Neural Networks (ANNs) classifier. In addition, the results show that the TCRE EEG (tEEG) provides approximately a four times enhancement in the signal-to-noise ratio (SNR) compared to disc electrode signals. We also evaluated the interdependency level between neighboring electrodes from tri-polar, disc, and disc with Hjorth's Laplacian method in time and frequency domains by calculating the mutual information (MI) and coherence. The MRP signals recorded with the TCRE system have significantly less mutual information (MI) between electrodes than the conventional disc electrode system and disc electrodes with Hjorth's Laplacian method. Also, the results show that the mean coherence between neighboring tri-polar electrodes was found to be significantly smaller than disc electrode and disc electrode with Hjorth's method, especially at higher frequencies. This lower coherence in the high frequency band between neighboring tri polar electrodes suggests that the TCREs may record a more localized neuronal activity. The successful decoding of finger movements can provide extra degrees of freedom to drive brain computer interface (BCI) applications, especially for neurorehabilitation.
Open Access
A data-driven approach for maximizing available wind energy through a dedicated pricing mechanism for charging residential plug-in electric vehicles
(Colorado State University. Libraries, 2019) Eldali, Fathalla, author; Suryanarayanan, Siddharth, advisor; Collins, George J., committee member; Zimmerle, Dan, committee member; Abdel-Ghany, Salah, committee member
Wind energy generation is growing significantly because of its favorable attributes such as cost-effectiveness and environment-friendliness. Electricity is the most perishable commodity as it must be consumed almost instantaneously as it is produced. Because of that, the variable nature of wind power generation and the challenges in forecasting the output power of wind impose problems of curtailment (excess of available wind energy than forecast) and deployment of reserves (deficit of available wind energy than forecast). Energy storage for wind power installations is a potential solution; however, storing large amounts of energy over long time periods is an expensive and inefficient solution. Plug-in electric vehicles (PEVs) are recognized as one of the assets to integrate energy storage on the distribution side of the electricity grid. Thus, PEVs charging presents an alternative solution for managing this excess energy in wind energy-rich grids. An accurate wind power forecasting (WPF) in the day-ahead market leads to a more predictable dispatch and unit-commitment (UC) of generators, thus reducing the need for reserves and storage. Typically, reserves to match the imbalance in supply and demand of electricity are provided by generators that are more expensive than the ones engaged in primary services. Markets in different regions of the world have specific designs, operation policies, and regulations when it comes to variable sources (e.g., wind, and solar). Independent system operators (ISOs), tasked with handling electricity markets in the US, must meet regulating reserve as directed by the North America Electric Reliability Council (NERC). One of these requirements is that the sufficient reserve must be available to cover the generation deficit. This deficit can be due to under-forecasting. There is also a case when ISOs need to curtail wind energy generation because of over-forecasting. In the first part of this dissertation, wind power data from the Electric Reliability Council of Texas (ERCOT) market is used to improve WPF as Texas has the highest installed wind energy capacity in the North American electricity grid. Autoregressive integrated moving average (ARIMA) model is used for WPF improvement. There is also a need to develop a coherent metric to quantify the improvements to WPF because different studies use different metrics. Also, using the statistical representation of the reduction in error does not necessarily reflect the overall benefit, especially the economic benefit, for ISOs. In the second part of this dissertation work, modifications of on risk-adjusted metrics used in investments assessments are developed and applied to the operation cost (OC). OC is the result of running the economic dispatch (ED) on realistic synthetic models of the actual Texas grid to evaluate the impact of the WPF improvement on the cost of operation. The modifications of the above-mentioned risk-adjusted metrics are also applied to deferring the capital investment on the distribution systems. Then, the metrics are used to assess the combination of photovoltaic (PV) and battery energy storage system (BESS) at the residential section of the distribution grid as explained in appendix A. The third part of this dissertation uses a data-driven approach to investigate existing pricing mechanisms for a Texan city (i.e., Austin) located in a wind energy-rich grid such as ERCOT with an increased adoption rate of PEVs. The study performed indicates the need for an alternative dynamic pricing mechanism dedicated to PEVs than the existing choices for maximizing the utility of available energy from wind in the absence of grid-level energy storage. Dynamic pricing produces an opportunity to avoid high costs for the power provider and benefits the consumers if they respond to the change of the price. However, achieving these benefits needs smart rate design and real data. After justifying the need for fair pricing mechanisms to benefit the utility and the customers for the coordination of wind energy and PEVs charging in wind energy-rich grid, this dissertation designs a time-varying pricing mechanism. This dissertation employs a data decomposition technique to design a dedicated pricing mechanism for PEVs. We use real data of a city with high projections of PEVs (Austin, Texas) located in a wind-rich electricity grid (ERCOT) to demonstrate this design of a dynamic pricing method.
Open Access
Analysis of genome-wide targets of Arabidopsis signal responsive 1 (AtSR1) transcription factor and its transcript stability in response to stress
(Colorado State University. Libraries, 2017) Abdel-Hameed, Amira, author; Reddy, A. S. N., advisor; Bush, Daniel, committee member; Leach, Jan, committee member; Abdel-Ghany, Salah, committee member
Abiotic and biotic stresses cause significant yield losses in all crops. Acquisition of stress tolerance in plants requires rapid reprogramming of gene expression. SR1/CAMTA3, a member of signal responsive transcription factors (TFs), functions both as a positive and a negative regulator of biotic stress responses and as a positive regulator of cold stress-induced gene expression. Using high throughput RNA-seq, we identified ~3000 SR1-regulated genes. Promoters of about 60% of the differentially expressed genes have a known DNA binding site for SR1, suggesting that they are likely direct targets. Gene ontology analysis of SR1-regulated genes confirmed previously known functions of SR1 and uncovered a potential role for this TF in salt stress. Our results showed that SR1 mutant is more tolerant to salt stress than the wild type and complemented line. Improved tolerance of sr1 seedlings to salt is accompanied with the induction of salt-responsive genes. Furthermore, ChIP-PCR results showed that SR1 binds to promoters of several salt-responsive genes. These results suggest that SR1 acts as a negative regulator of salt tolerance by directly repressing the expression of salt-responsive genes. Overall, this study identified SR1-regulated genes globally and uncovered a previously uncharacterized role for SR1 in salt stress response. Soil salinity, one of the most prevalent environmental stresses, causes enormous losses in global crop yields every year. Therefore, it is imperative to generate salt tolerant cultivars. To achieve this goal, it is essential to understand the mechanisms by which plants respond to and cope with salt stress. Stress-induced reprogramming of gene expression at multiple levels contributes to the survival of plants under adverse environmental conditions. The control of mRNA stability is one of the post-transcriptional mechanisms that is highly regulated under stress conditions leading to changes in expression pattern of many genes. In this study, we show that salt stress increases the level of SR1 mRNA, by enhancing its stability. Multiple lines of evidence indicate that ROS generated by NADPH oxidase activity mediate salt-induced SR1 transcript stability. Furthermore, cycloheximide (CHX), a protein synthesis inhibitor, also increased SR1 mRNA stability, albeit to a higher level than in the presence of salt, suggesting a role for one or more labile proteins in SR1 mRNA turnover. Similar to salt, ROS generated by NADPH oxidase is also involved in CHX-induced SR1 mRNA accumulation. To gain further insights into mechanisms involved in saltand CHX-induced SR1 stability, the roles of different mRNA degradation pathways were examined in mutants that are impaired in either nonsense-mediated decay (NMD) or mRNA decapping pathways. These studies have revealed that neither the NMD pathway nor the decapping of SR1 mRNA is required for its decay. However, decapping activity is required for saltand CHXaccumulation of SR1 mRNA. To identify any specific regions within the open reading frame of the SR1 transcript (~3 kb) that are responsible for the salt-induced accumulation of SR1 mRNA, we generated transgenic lines expressing several truncated versions of the SR1 coding region in the sr1 mutant background. Then, we analyzed accumulation of each version in response to salt stress and CHX. Interestingly, we identified a 500 nts region in the 3' end of the SR1 coding sequence to be required for both saltand CHX-induced stability of SR1 mRNA. Potential mechanisms by which this region confers SR1 transcript stability in response to salt and CHX are discussed.
Open Access
Learner-centered comparison study between American native speakers and Saudi English language learners in forming English requests and refusals in academic setting
(Colorado State University. Libraries, 2018) Alqarawi, Nahlah, author; Delahunty, Gerald, advisor; Becker, Anthony, committee member; Abdel-Ghany, Salah, committee member
Native speakers of a language may not consider cultural differences when performing speech acts which can lead to misunderstandings between people from different cultures. Therefore, this study investigates differences between Saudi Arabic learners of English and American English speakers in how requests and refusals are realized. Specifically, the goal of this research is to look at different factors that go into forming a request or a refusal such as formality, social status, and scale of directness. Using a Discourse Completion Task, this study examined the significant differences between American Native Speakers (n=15) and Saudi Native Speakers (n=15) to explore the frequency of request and refusal strategies. Overall, findings in the study resulted in statistically significant differences in participant's requests. It was also found that ANSs used significantly more requests than did SNSs. Additionally, ANSs used way more sub-strategies than did SNSs. For refusals however, no statistically significant difference was found. There was a wider use of refusal strategies by SNSs; ANSs used certain refusal strategies more extensively. Some implications for the findings include identifying authentic requests and refusals selected from an American academic spoken corpus or by role plays with hypothetical request and refusal situations.

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Browsing 2000-2019 by Author "Abdel-Ghany, Salah, committee member"

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