Engineering Commons^™

Fischer–Tropsch: Product Selectivity–The Fingerprint Of Synthetic Fuels, Wilson D. Shafer, Muthu Kumaran Gnanamani, Uschi M. Graham, Jia Yang, Cornelius M. Masuku, Gary Jacobs, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

The bulk of the products that were synthesized from Fischer–Tropsch synthesis (FTS) is a wide range (C₁–C₇₀₊) of hydrocarbons, primarily straight-chained paraffins. Additional hydrocarbon products, which can also be a majority, are linear olefins, specifically: 1-olefin, trans-2-olefin, and cis-2-olefin. Minor hydrocarbon products can include isomerized hydrocarbons, predominantly methyl-branched paraffin, cyclic hydrocarbons mainly derived from high-temperature FTS and internal olefins. Combined, these products provide 80–95% of the total products (excluding CO₂) generated from syngas. A vast number of different oxygenated species, such as aldehydes, ketones, acids, and alcohols, are also embedded in this product range. …

Effect Of Stoniness On The Hydraulic Properties Of A Soil From An Evaporation Experiment Using The Wind And Inverse Estimation Methods, Nerea Arias, Iñigo Virto, Alberto Enrique, Paloma Bescansa, Riley Walton, Ole O. Wendroth

Plant and Soil Sciences Faculty Publications

Stony soils are distributed all over the world. The study of their characteristics has gained importance lately due to their increasing use as agricultural soils. The effect that rock fragments exert on the soil hydraulic properties is difficult to measure in situ, and is usually derived from the fine earth properties. However, the corrections used so far do not seem accurate for all types of stony soils. Our objective was to assess the adequacy of estimating the hydraulic properties of a stony soil from the fine earth ones by correcting the latter by the volume occupied by rock fragments. To …

Limits To The World’S Green Water Resources For Food, Feed, Fiber, Timber, And Bioenergy, Joep F. Schyns, Arjen Y. Hoekstra, Martijn J. Booij, Rick J. Hogeboom, Mesfin Mekonnen

Daugherty Water for Food Global Institute: Faculty Publications

Green water––rainfall over land that eventually flows back to the atmosphere as evapotranspiration––is the main source of water to produce food, feed, fiber, timber, and bioenergy. To understand how freshwater scarcity constrains production of these goods, we need to consider limits to the green water footprint (WFg), the green water flow allocated to human society. However, research traditionally focuses on scarcity of blue water––groundwater and surface water. Here we expand the debate on water scarcity by considering green water scarcity (WSg). At 5 × 5 arc-minute spatial resolution, we quantify WFg and the maximum sustainable level to this footprint (WFg,m), …

Theoretical Research On The Ploughing Rock Breaking Properties Of New Conical Pdc Cutter, Ju Pei, Wang Chuanliu

Coal Geology & Exploration

The researches on the conical PDC cutter are now focused on numerical simulation, field and laboratory tests, the theoretical analysis on its mechanical properties has not been reported. Therefore, the tensile shear rock breaking mechanism and cutting load distribution characteristics of the conical PDC cutter are described by numerical simulation, the theoretical formula of the cutting load is derived according to the energy balance principle. Results show that comparing with the conventional cylindrical PDC cutter, the rock breaking process of conical PDC cutter is more stable, the cutting load is influenced by the rock properties, the parameters of cutter structure, …

Effect Of Pt Promotion On The Ni-Catalyzed Deoxygenation Of Tristearin To Fuel-Like Hydrocarbons, Ryan Loe, Kelsey Huff, Morgan Walli, Tonya Morgan, Dali Qian, Robert Pace, Yang Song, Mark Isaacs, Eduardo Santillan-Jimenez, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Pt represents an effective promoter of supported Ni catalysts in the transformation of tristearin to green diesel via decarbonylation/decarboxylation (deCO_x), conversion increasing from 2% over 20% Ni/Al₂O₃ to 100% over 20% Ni-0.5% Pt/Al₂O₃ at 260 °C. Catalyst characterization reveals that the superior activity of Ni-Pt relative to Ni-only catalysts is not a result of Ni particle size effects or surface area differences, but rather stems from several other phenomena, including the improved reducibility of NiO when Pt is present. Indeed, the addition of a small amount of Pt to the supported Ni …

Continuous Catalytic Deoxygenation Of Waste Free Fatty Acid-Based Feeds To Fuel-Like Hydrocarbons Over A Supported Ni-Cu Catalyst, Ryan Loe, Yasmeen Lavoignat, Miranda Maier, Mohanad Abdallah, Tonya Morgan, Dali Qian, Robert Pace, Eduardo Santillan-Jimenez, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

While commercial hydrodeoxygenation (HDO) processes convert fats, oils, and grease (FOG) to fuel-like hydrocarbons, alternative processes based on decarboxylation/decarbonylation (deCO_x) continue to attract interest. In this contribution, the activity of 20% Ni-5% Cu/Al₂O₃ in the deCO_x of waste free fatty acid (FFA)-based feeds—including brown grease (BG) and an FFA feed obtained by steam stripping a biodiesel feedstock—was investigated, along with the structure-activity relationships responsible for Ni promotion by Cu and the structural evolution of catalysts during use and regeneration. In eight-hour experiments, near quantitative conversion of the aforementioned feeds to diesel-like hydrocarbons was achieved. …

Irrigation Water Quality—A Contemporary Perspective, Arindam Malakar, Daniel D. Snow, Chittaranjan Ray

Nebraska Water Center: Faculty Publications

In the race to enhance agricultural productivity, irrigation will become more dependent on poorly characterized and virtually unmonitored sources of water. Increased use of irrigation water has led to impaired water and soil quality in many areas. Historically, soil salinization and reduced crop productivity have been the primary focus of irrigation water quality. Recently, there is increasing evidence for the occurrence of geogenic contaminants in water. The appearance of trace elements and an increase in the use of wastewater has highlighted the vulnerability and complexities of the composition of irrigation water and its role in ensuring proper crop growth, and …

Twenty-Three Unsolved Problems In Hydrology (Uph) – A Community Perspective, Günter Blöschl, Christopher M. U. Neale, A Cast Of Thousands

Daugherty Water for Food Global Institute: Faculty Publications

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused …

Cadmium Sulfide-Buffered Pv Systems: Assessing The Environmental, Health, And Economic Impacts, Maqsood Ali Mughal, Rajesh Sharma

Journal of the Arkansas Academy of Science

As the world’s population continues to grow, global energy crises are expected to rise in the future, thus accelerating the demand for renewable energy technology, particularly solar photovoltaics. The energy sector will face an increasingly complex array of interlocking challenges - technological, environmental, health, economic, and regulatory. In this paper, we study CdS, a widely used buffer material in thin film photovoltaics, to assess and monetize environmental, health, and socio-economic externalities associated with the use of the material. Currently, CdS has a significant advantage over other alternate buffer materials in terms of efficiency and low-cost production of large-area processing of …

Modeled And Measured Ecosystem Respiration In Maize–Soybean Systems Over 10 Years, Ming Zhan, Adam Liska, Anthony Nguy-Robertson, Andrew E. Suyker, Matthew P. Pelton, Haishun Yang

Adam Liska Papers

Crop residue is an abundant resource for the potential production of biofuels, but a better understanding of its use on net carbon emissions must be developed to mitigate climate change. This analysis combines two established crop growth models (Hybrid-Maize and SoySim) with a simple soil and crop residue respiration model to estimate daily ecosystem respiration (ERe) from maize and soybean; ERe was estimated to be the sum of CO₂ emissions from the oxidation of the growing crop, crop residue, and soil organic carbon (SOC). Model-estimated CO₂ fluxes from irrigated continuous maize and irrigated maize–soybean cropping systems in eastern …

Environmental Policy Assessment In The Ghanaian Gold Mining Industry: Insights From Stakeholders, Francis Tuokuu

Antioch University Dissertations & Theses

Environmental policy assessment has been recognized by critical stakeholders (e.g., governments, local communities, academics, environmental advocacy groups, and mining companies) as an effective way of identifying and dealing with the myriad of environmental problems confronting humanity, particularly those caused by mining activities. While the gold mining sector has contributed to the economies of countries in Sub-Saharan Africa since the introduction of structural adjustment programs (SAPs) in the 1980s by the Bretton Woods institutions (the World Bank and the International Monetary Fund; IMF), the sector has also contributed to environmental degradation including water pollution, land contaminations, and generally, human health concerns …

Offshore Wind Farms And Maritime Navigational Risks, Syed Raza Ali Mehdi

World Maritime University Ph.D. Dissertations

The offshore wind energy sector (OWE) has experienced significant growth in the last few decades. Since the inception of the very first offshore wind farm (OWF) – Vindeby – in 1991, there have been major improvements in materials, structures, aerodynamics, hydrodynamics technologies, as well as substantial developments in installation, operations, maintenance and decommissioning strategies. These advances have led to a rapid increase in the numbers and sizes of both offshore winds turbines (OWTs) and OWFs, and driven down the cost of OWE generation. With further improvements imminent, and increasing societal popularity, the strong evolution of the OWE sector is predicted …

Water, Energy, And Carbon Footprints Of Bioethanol From The U.S. And Brazil, Mesfin Mekonnen, Thiago L. Romanelli, Chittaranjan Ray, Arjen Y. Hoekstra, Adam Liska, Christopher M. U. Neale

Adam Liska Papers

Driven by biofuel policies, which aim to reduce greenhouse gas (GHG) emissions and increase domestic energy supply, global production and consumption of bioethanol have doubled between 2007 and 2016, with rapid growth in corn-based bioethanol in the U.S. and sugar cane-based bioethanol in Brazil. Advances in crop yields, energy use efficiency in fertilizer production, biomass-to-ethanol conversion rates, and energy efficiency in ethanol production have improved the energy balance and GHG emission reduction potential of bioethanol. In the current study, the water, energy, and carbon footprints of bioethanol from corn in the U.S. and sugar cane in Brazil were assessed. The …

Including Farmer Irrigation Behavior In A Sociohydrological Modeling Framework With Application In North India, Jimmy O’Keeffe, Simon Moulds, Emma Bergin, Nick Brozovic, Ana Mijic, Wouter Buytaert

Daugherty Water for Food Global Institute: Faculty Publications

Understanding water user behavior and its potential outcomes is important for the development of suitable water resource management options. Computational models are commonly used to assist water resource management decision making; however, while natural processes are increasingly well modeled, the inclusion of human behavior has lagged behind. Improved representation of irrigation water user behavior within models can provide more accurate and relevant information for irrigation management in the agricultural sector. This paper outlines a model that conceptualizes and proceduralizes observed farmer irrigation practices, highlighting impacts and interactions between the environment and behavior. It is developed using a bottom-up approach, informed …

Recent Trends In The Frequency And Duration Of Global Floods, Nasser Najibi, Naresh Devineni

Publications and Research

Frequency and duration of floods are analyzed using the global flood database of the Dartmouth Flood Observatory (DFO) to explore evidence of trends during 1985–2015 at global and latitudinal scales. Three classes of flood duration (i.e., short: 1–7, moderate: 8–20, and long: 21 days and above) are also considered for this analysis. The nonparametric Mann–Kendall trend analysis is used to evaluate three hypotheses addressing potential monotonic trends in the frequency of flood, moments of duration, and frequency of specific flood duration types. We also evaluated if trends could be related to large-scale atmospheric teleconnections using a generalized linear model framework. …

Sustainable Agriculture: Integration Of Aquaponics At Punta Leona Hotel And Club In Costa Rica, Cailin Sierra Dyer, Paris Riley Smith

Senior Honors Projects, 2010-2019

Sustainable agriculture is becoming an increasingly important method of food production. As human populations continue to grow, attendant food demand has been increasingly met via agribusiness, including monoculture crop production and factory farming. As is well documented, the rise of agribusiness has led to resource degradation and declining stocks on which “sustainable agriculture” relies. This paper describes a local attempt to re-establish “sustainable agriculture” through the development of an aquaculture system that mimics a naturally occurring cycle that integrates fish and plants. The system was constructed over a three-week period in Punta Leona, Costa Rica. First, the ground was cleared …

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium, …

Single-Stage, Venturi-Driven Desalination System, Brandon Proetto

Mechanical & Aerospace Engineering Theses & Dissertations

Water demand is increasing at a rapid pace due to population increase, industrial expansion, and agricultural development. The use of desalination technology to meet the high water demands has increased global online desalination capacity from 47 million m^3/d in 2007 to 92.5 million m^3/d as of June 2017 [49]. Membrane and thermal processes are the two mainstream desalination categories used worldwide for desalination plants. Reverse Osmosis (RO) is the most widely used membrane process and it has become the dominant technology for building desalination plants over recent decades. Thermal distillation, however, has become less and less competitive due to its …

Assessment Of Drinking Water Quality Management And A Treatment Feasibility Study For Brick By Brick Water Storage Tanks In Rakai Uganda, James V. Murduca

USF Tampa Graduate Theses and Dissertations

Reliable access to safe drinking water is one necessity for humans to live without concern for major health risks. The overall goal of this research is to improve the public health, through improved drinking water, for communities in the Rakai District in Uganda, directly, and other communities in the world, indirectly, via dissemination of knowledge. This study specifically assessed the knowledge of drinking water quality in regards to public health, their sanitation measures, and water treatment methods for users of Brick by Brick rainwater harvesting tanks in the Rakai District (N = 28) by using a knowledge, attitudes, and practice …

Design And Implementation Of A Ferrocement Improved Cookstove In Rural Panama, Josh Donegan

USF Tampa Graduate Theses and Dissertations

Household air pollution contributes to the premature death of more than 4 million people annually. Improved cookstoves are one technological intervention that can potentially reduce exposure to household air pollution. However, improved cookstove implementation programs need to consider measures to increase sustainability and promote long-term adoption. The objectives of this research were 1) to develop and implement a new ferrocement cookstove for Peña Blanca, a rural indigenous community in the Ngäbe-Bugle region of Panama, 2) to evaluate its potential sustainability in comparison to the most common cooking technologies observed in the community, 3) to prepare a construction manual for the …

Apprehensive Drought Characteristics Over Iraq: Results Of A Multidecadal Spatiotemporal Assessment, Maysoun Ayad Hameed, Ali Ahmadalipour, Hamid Moradkhani

Civil and Environmental Engineering Faculty Publications and Presentations

Drought is an extreme climate phenomenon that happens slowly and periodically threatens the environmental and socio-economic sectors. Iraq is one of the countries in the Middle East that has been dealing with serious drought-related issues in the 21st century. Here, we investigate meteorological drought across Iraq from 1948 to 2009 at 0.25° spatial resolution. The Standardized Precipitation Evapotranspiration Index (SPEI) has been utilized as a multi-scalar drought index accounting for the effects of temperature variability on drought. Four of the main characteristics of drought including extent, intensity, frequency and duration are studied and the associated spatiotemporal patterns are investigated for …

Global Anthropogenic Phosphorus Loads To Freshwater And Associated Grey Water Footprints And Water Pollution Levels: A High-Resolution Global Study, Mesfin Mekonnen, Arjen Y. Hoekstra

Daugherty Water for Food Global Institute: Faculty Publications

We estimate the global anthropogenic phosphorus (P) loads to freshwater and the associated grey water footprints (GWFs) for the period 2002–2010, at a spatial resolution of 5 3 5 arc min, and com- pare the GWF per river basin to runoff to assess the P-related water pollution level (WPL). The global anthro- pogenic P load to freshwater systems from both diffuse and point sources is estimated at 1.5 Tg/yr. More than half of this total load was in Asia, followed by Europe (19%) and Latin America and the Caribbean (13%). The domestic sector contributed 54% to the total, agriculture 38%, …

Modeling Water Availability, Risk And Resilience In A Semi-Arid Basin In Southern Africa, Esther N. Mosase

Electronic Theses and Dissertations

Climate variability need to be incorporated into the management and planning of water resources, particularly in arid and semi-arid regions, where water availability is more sensitive to rainfall and air temperature. This study used modified Man-Kendall trend analysis test and ArcGIS to process data. Annual means of rainfall, minimum temperature and maximum temperature in the Limpopo River Basin (LRB) varied between 160 and 1109 mm, 8 °C to 20 °C and 23 °C to 32 °C respectively. The spatial pattern is generally increasing from west to east for rainfall and minimum temperature while maximum temperature increases from south to north …

Evaluating E. Coli Particle Attachment And The Impact On Transport During High Flows, Louis Amegbletor

Electronic Theses and Dissertations

Fecal indicator bacteria, including E. coli, are the leading cause of water quality impairments within assessed waters in the United States. The source of E. coli includes WWTP, leaking sewers, animal manure, wildlife, livestock, and stream bed sediment. Storm events contribute to bacteria loading within waters through wash-in of land sources of bacteria and resuspension of bacteria within sediments. Bacteria introduced into the water column are either attached to particles or are unattached (or free-living). The goal of this study was to examine the attachment of E. coli to different particle sizes, including their impact on contributing to water …

Evaluating The Role Of Energy Demand Prediction And Renewable Energy Utilization On Energy Dependency Management: A Generic System Dynamics Model, Emad Rabiei Hosseinabad

Graduate Research Theses & Dissertations

Supplying energy has become one of the biggest concerns of developed countries due to the growing energy needs in the last decades. Security of energy supply has forced countries to rely more on energy imports from external sources, and become energy dependent to a greater extent. Utilizing available renewable energy resources has been characterized as a reliable indicator to mitigate energy dependency in countries as well as securing the supplying of energy-based needs in the future. This research explores the impact of renewable energies as trustful resources in mitigating energy imports form external sources with investigation of its viability with …

Predicting Energy And Water Consumption On Dairy Farms Through Statistical Analysis And Machine-Learning Methods, Philip Shine

Theses

With the abolishment of milking quotas across all European Union member states in April 2015, dairy farmers must adjust their farming practises to minimise milk production costs to adequately prepare for potential periods of reduced revenue. Milk production is an intense energy and water consuming process. Coupled with challenging European greenhouse gas reduction targets and legislation regarding the prevention of groundwater pollution and deterioration, increasing the production of milk in Ireland must be met with the sustainable consumption of on-farm energy and direct water resources, to ensure the future monetary and environmental sustainability of Ireland’s dairy industry. Thus, this body …

Abiotic- And Biotic-Formation Of Manganese Oxides And Their Fate In Environmental Systems, Haesung Jung

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese (hydr)oxide (Mn (hydr)oxide) minerals are ubiquitous in aquatic and terrestrial environments. These minerals have high surface areas and are highly sorptive and redox active. From decades of accumulated knowledge about natural redox cycling, we have found that Mn (hydr)oxides play critical roles as electron donors and acceptors in elemental geochemical cycling and biological metabolisms in nature. Thus, Mn (hydr)oxides have garnered increasing interest to understand natural systems. Considering the variety of redox reactions with Mn (hydr)oxides in nature, it is also expected that there should be diverse pathways to form Mn (hydr)oxides through abiotic and biotic processes. Previous studies …

College Of Engineering Senior Design Competition Fall 2017, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

Evaluation Of Water Resources And Hydraulic Influences In The Restoration Of The Western Part Of The Mesopotamian Marshlands, Ali Kareem Al-Quraishi

Graduate Theses and Dissertations

The purpose of this study is to assess the water resources and water conveyance system of the western part of the Mesopotamian marshes (Al-Hammar marsh) as well as develop a water conveyance system to distribute water throughout the western Al-Hammar marsh. These processes are significant to identify the current restoration problems and help to create restoration strategies for the marsh. Also, proper management strategy to the Al-Hammar marsh is necessary to preserve the marsh ecosystem, irrigate lands, and provide domestic necessities in the villages.

The overall project is divided into three main chapters which address the current ecological and hydrological …

Sustainability Of Community-Managed Rural Water Supply Systems In Amazonas, Peru: Assessing Monitoring Tools And External Support Provision, Jacob E. Mangum

USF Tampa Graduate Theses and Dissertations

Globally, there is still a large number of people without access to safe drinking water; a known health risk. In rural areas of countries like Peru, when potable water systems are built the responsibility for maintaining these systems is given to volunteer water committees. Despite its prevalence as a management model, there is a consensus that community management alone cannot ensure sustainable water service. Therefore, the overall goal of this research is to assess the sustainability of community-managed water systems in rural areas of the department of Amazonas, Peru. Specifically, this research examines two mechanisms that have been shown to …