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2019

Portland State University

Theses/Dissertations

Dissertations and Theses

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Articles 31 - 37 of 37

Full-Text Articles in Engineering

On The Drought Recovery And Resiliency: How Terrestrial And Riverine Ecosystems Recover From Agricultural And Hydrological Droughts, Behzad Ahmadi Mar 2019

On The Drought Recovery And Resiliency: How Terrestrial And Riverine Ecosystems Recover From Agricultural And Hydrological Droughts, Behzad Ahmadi

Dissertations and Theses

Climate extremes, in particular droughts are significant driving forces towards riverine and terrestrial ecosystems disturbance. Drought impacts on stream ecosystems include losses that can either be direct (e.g. destruction of habitat for aquatic species) or indirect (e.g. deterioration of water quality, soil quality, and increased chance of wildfires). This study investigates hydrological and agricultural droughts and their recovery durations. For the riverine ecosystems, this study combines hydrologic drought and water quality changes during droughts and represents a multi-stage framework to detect and characterize hydrological droughts, while considering water quality parameters. Hydrological droughts are categorized into three stages of growth, persistence, …


Efficient Methods For Robust Circuit Design And Performance Optimization For Carbon Nanotube Field Effect Transistors, Muhammad Ali Mar 2019

Efficient Methods For Robust Circuit Design And Performance Optimization For Carbon Nanotube Field Effect Transistors, Muhammad Ali

Dissertations and Theses

Carbon nanotube field-effect transistors (CNFETs) are considered to be promising candidate beyond the conventional CMOSFET due to their higher current drive capability, ballistic transport, lesser power delay product and higher thermal stability. CNFETs show great potential to build digital systems on advanced technology nodes with big benefits in terms of power, performance and area (PPA). Hence, there is a great need to develop proven models and CAD tools for performance evaluation of CNFET-based circuits. CNFETs specific parameters, such as number of tubes, pitch (spacing between the tubes) and diameter of CNTs determine current driving capability, speed, power consumption and area …


Behavior Of Non-Ductile Slender Reinforced Concrete Columns Retrofit By Cfrp Under Cyclic Loading, Wisam Amer Aules Mar 2019

Behavior Of Non-Ductile Slender Reinforced Concrete Columns Retrofit By Cfrp Under Cyclic Loading, Wisam Amer Aules

Dissertations and Theses

In the Middle East region and many countries in the world, older reinforced concrete (RC) columns are deemed to be weak in seismic resistance because of their low amount of reinforcement, low grades of concrete, and large spacing between the transverse reinforcement. The capacity of older RC columns that are also slender is further reduced due to the secondary moments. Appropriate retrofit techniques can improve the capacity and behavior of concrete members. In this study, externally bonded Carbon Fiber Reinforced Polymer (CFRP) retrofit technique was implemented to improve the behavior of RC columns tested under constant axial load and cyclic …


Seismic Behavior Of Screen Grid Core Insulated Concrete Form Walls, Anwer Sabah Mohammed Mohammed Mar 2019

Seismic Behavior Of Screen Grid Core Insulated Concrete Form Walls, Anwer Sabah Mohammed Mohammed

Dissertations and Theses

The use of the insulated concrete form (ICF) walls in residential buildings has increased over the past few decades. Much research has been conducted to evaluate the lateral strength of these walls by applying monotonic and cyclic loadings. In the current study, full-scale shake table experiments were employed to evaluate the in-plane behavior of four screen grid insulated concrete form (SGICF) walls. The first two wall specimens utilized dry fit insulated form blocks made from recycled expanded polystyrene granules that were bonded together with cement. When stacked, the cavities in the blocks formed a grid of cores that are evenly …


Spectral Clustering For Electrical Phase Identification Using Advanced Metering Infrastructure Voltage Time Series, Logan Blakely Jan 2019

Spectral Clustering For Electrical Phase Identification Using Advanced Metering Infrastructure Voltage Time Series, Logan Blakely

Dissertations and Theses

The increasing demand for and prevalence of distributed energy resources (DER) such as solar power, electric vehicles, and energy storage, present a unique set of challenges for integration into a legacy power grid, and accurate models of the low-voltage distribution systems are critical for accurate simulations of DER. Accurate labeling of the phase connections for each customer in a utility model is one area of grid topology that is known to have errors and has implications for the safety, efficiency, and hosting capacity of a distribution system. This research presents a methodology for the phase identification of customers solely using …


Application Of Improved Feature Selection Algorithm In Svm Based Market Trend Prediction Model, Qi Li Jan 2019

Application Of Improved Feature Selection Algorithm In Svm Based Market Trend Prediction Model, Qi Li

Dissertations and Theses

In this study, a Prediction Accuracy Based Hill Climbing Feature Selection Algorithm (AHCFS) is created and compared with an Error Rate Based Sequential Feature Selection Algorithm (ERFS) which is an existing Matlab algorithm. The goal of the study is to create a new piece of an algorithm that has potential to outperform the existing Matlab sequential feature selection algorithm in predicting the movement of S&P 500 (^GSPC) prices under certain circumstances. The two algorithms are tested based on historical data of ^GSPC, and Support Vector Machine (SVM) is employed by both as the classifier. A prediction without feature selection algorithm …


From Drought To Food-Energy-Water-Security Nexus: An Assessment Of Food Insecurity In The Middle East, Maysoun Ayad Hameed Jan 2019

From Drought To Food-Energy-Water-Security Nexus: An Assessment Of Food Insecurity In The Middle East, Maysoun Ayad Hameed

Dissertations and Theses

Drought is an extreme climate phenomenon that happens slowly and periodically threatens the environmental and socio-economic sectors. Developing countries have experienced crucial conditions in meeting the needs for food, energy, and water security. Natural disasters contribute as risky sources of food insecurity and vulnerability in the Middle East. This dissertation presents a country-level review and quantitative assessment of the current issues associated with the Food-Energy-Water-Security (FEWS) Nexus in the Middle East. In this study, sixteen countries in the Middle East are chosen, namely, Arabian Peninsula, Iran, Syria, Lebanon, Israel, Palestine, Egypt, and Turkey. The most recent datasets are used to …