Engineering Commons^™

Post-Liquefaction Residual Strength Assessment Of The Las Palmas, Chile Tailings Failure, Tristan Reyes Gebhart

Master's Theses

Assessment of post-liquefaction residual strength is needed for the development of empirically-based, predictive correlations for earthquake engineering design. Previous practice commonly assigned negligible strengths to liquefied materials for engineering analysis, producing overly-conservative designs. Increasingly available case history data, and improved analytical tools have allowed for more accurate and less overly-conservative estimation of soil residual strength, improving empirical predictive models. This study provides a new case history to the limited suite of (approximately 30) liquefaction failure case histories available for post-liquefaction in-situ strength predictive correlations.

This case history documents the Las Palmas gold mine tailings dam failure, resulting from seismic-induced liquefaction …

The Feasibility Of Utilising Compressed Natural Gas As Part Of A Systematic Approach To Establishing The Necessary Groundwork For The Hydrogen Based Transport Economy, James Brunton, John Howlett, David Kennedy

Conference Papers

One key objective for vehicle manufacturers is to develop technology and infrastructure to facilitate the progression from combustion to conversion by the year 2050. In the short to medium term however, the combustion of fossil fuels such as petrol and diesel, coupled with advanced transmission innovations and emission control technology that are governed by strict Euro VI regulations appears to be the main path forward for the transport sector and the environment. This paper presents the feasibility of utilising the developing compressed natural gas network capabilities as part of a systematic approach to establishing the necessary groundwork for a hydrogen …

Technological Assessment Of Different Solar-Biomass Systems For Hybrid Power Generation In Europe, Cm Iftekhar Hussain, Brian Norton, Aidan Duffy

Articles

Solar Tower thermal (ST), Parabolic Trough thermal (PT), Linear Fresnel thermal (LF) and Solar PV are discussed in the context of suitability for hybridization with biomass in Europe. Technical, economical and climate data have been compared to identify the key drivers of technology selection in setting up large scale solar-biomass hybrid power plants. The sole solar-biomass hybrid power plant is currently in operation in Spain uses PT technology due to its performance characteristics, comparatively easy installation process compared to ST and relatively higher heat and optical gain than LF. The climate condition in the EU shows that the region within …

Real-Time Monitoring Of Sand And Dust Storm Winds Using Wireless Sensor Technology, Hana Mohammed Mujlid

Theses and Dissertations

This dissertation proposes an empirical model for prediction of the radio path loss in Wireless Sensor Networks (WSNs). The model applies to WSNs that are deployed in environments with dust and sand storms. It is developed as a result of statistical analysis of the measured data collected during dust and sand storms. The measured data were obtained at 2.4GHz and for different levels of the storm severity. For the purpose of data collection a custom measurement system based on Xbee air interface was developed. The proposed model shows a very good agreement with the measured data. It is also demonstrated …

Environmental Damage Risk Assessment And Emergency Scheme Of Ship Oil Spill Around Xiamen Sea, Congchao Zhang

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

Abstracts From The 2016 Ahac Conference, Erick Agrimson

2017 Academic High Altitude Conference

This is a listing of Abstracts from AHAC 2016

Scientific Review Report, J D. Rossouw, M Musariri

Policy

This report provides the Scientific Review results and recommendations regarding the existing surface and groundwater monitoring sites for all nine Water Management Areas following the Regional WMA Network Design Workshops held in Nelspruit, Cape Town, Durban,King Williams Town, Bela-Bela and Bloemfontein from March to June 2016. During these workshops theoretical monitoring network considerations for each WMA were presented to various stakeholders, and the considerations were used to review the existing networks and obtain changes and improvements to the networks as recommendations. The main objectives of the workshops were to review the existing monitoring networks against the prioritized National Monitoring Objectives …

A Study Of Applications Of 3d Animation For Emergency Medicine Pedagogy, Huilong Zheng

Open Access Theses

There is ample precedent for the use of 3D animation in education, though little research on specific applications in the field of medicine. An experiment was carried out to assess the suitability of 3D animation for educational purposes in emergency medicine courses. Two groups of experimental participants were assessed on their ability to respond to three emergency medical situations in simulated test scenarios. Both groups received equivalent information on how to treat the three different medical emergencies. The control group received the information in traditional lecture format. The experimental group instead received the information from a set of 3D animations. …

Investigation Of Exothermic Reaction Dynamics Via Computational Fluid Dynamics Coupled With A Feedback Controller, Siusan Choi

Mechanical and Aerospace Engineering Dissertations - Archive

The control of reaction temperature under continuous flow conditions is important in a variety of chemical manufacturing industries. For many reactions, operating at off-design temperatures can result in the production of undesired products, reduced feedstock conversion and, in some cases, reduced catalyst lifetime. In many exothermic reactions, maintaining a desired set point temperature at high reactant flow rates becomes challenging if the chemical kinetics exhibit highly non-linear behavior. In these situations, the interaction between commonly used linear controllers and the physical system can lead to unexpected dynamic response and undesired swings in reaction temperature. In this research, a computational model …

Evaluation Of Food Waste Diversion Potential And Economics Of Using Food Waste Dehydrators, Arindam Dhar

Civil Engineering Theses - Archive

According to US EPA (2013), food waste is the second largest component (14.6%) of MSW composition in the US, preceded only by paper. Apart from the negative environmental impacts of food waste through methane and leachate generation, it also incurs huge cost to landfill them. Hence, food waste diversion from landfills is becoming a major issue in landfills across many US states. Though biological treatment of food waste is a potential alternative for food waste diversion, the existing scale of this type of treatment is very narrow. On-site treatment of food waste is a suitable alternative as it can be …

Methods To Facilitate Community Participation In Humanitarian Engineering Projects: Laying The Foundation For A Learning Platform, Andrea Mazzurco

Open Access Dissertations

Humanitarian engineering (HE) is a new interdisciplinary field that is rapidly emerging worldwide. Many not-for-profit organizations such as Engineers Without Borders, Practical Action, and International Development Enterprise have been flourishing with the goal of providing technological solutions to those who need them the most. In engineering programs across the U.S., HE, service-learning, community engagement, and similar programs are gaining popularity because they offer an efficient way to meet ABET accreditation criteria, while also teaching valuable technical and professional skills to engineering students. However, the cultural, social, and political differences among communities and engineers often add degrees of difficulty that cannot …

The Influence Of The Electric Supply Industry On Economic Growth In Less Developed Countries, Edward Richard Bee

Dissertations

This study measures the impact that electrical outages have on manufacturing production in 135 less developed countries using stochastic frontier analysis and data from World Bank’s Investment Climate surveys. Outages of electricity, for firms with and without backup power sources, are the most frequently cited constraint on manufacturing growth in these surveys.

Outages are shown to reduce output below the production frontier by almost five percent in Africa and by a lower percentage in South Asia, Southeast Asia and the Middle East and North Africa. Production response to outages is quadratic in form. Outages also increase labor cost, reduce exports …

A Critical Review Of High Entropy Alloys (Heas) And Related Concepts, D.B. Miracle, O.N. Senkov

Beyond Nickel-Based Superalloys II

The field of high entropy alloys (HEAs) is barely 10 years old. It has stimulated new ideas and has inspired the exploration of the vast composition space. Here we give a critical review of this body of work, with the intent of summarizing key findings, uncovering major trends and providing guidance for future efforts. Based on detailed analysis, the following major results emerge. An intense focus is apparent on alloys based on first row transition metal elements. These efforts have discovered an extended, single-phase solid solution phase field and are exploring the extent and properties of this phase field. As …

Towards Nanoindentation At Application-Relevant Temperatures – A Study On Cmsx-4 Alloy And Amdry-386 Bond Coat, James Gibson, Sebastian Schröders, Christoffer Zehnder, Sandra Korte-Kerzel

Beyond Nickel-Based Superalloys II

With nickel-based superalloys reaching their fundamental limit in high-temperature applications, new alloys are required with improved mechanical properties. Small-scale mechanical testing – particularly nanoindentation – is of great benefit to alloy development, allowing hardness and modulus to be measured on small volumes of newly-developed materials.

We show that it is now possible to carry out such tests in vacuum up to 1000˚C, paving the way for candidate alloys and coatings to be tested at operation-relevant conditions. In this work, a <001> oriented single-crystal CMSX4 sample and a 200 µm Amdry-386 bond coat were tested using a modified MicroMaterials NanoTest indenter. 1 …

Γ/Γ' Co-Base Superalloys – New High Temperature Materials Beyond Ni-Base Superalloys?, Steffen Neumeier, Christopher H. Zenk, Lisa P. Freund, Mathias Göken

Beyond Nickel-Based Superalloys II

In 2006 a new L1₂ phase, Co₃(Al,W), was discovered in the Co-Al-W system which has led to the development of novel Co-base superalloys with g/g¢ microstructures similar to those of the well-established Ni-base superalloys. First investigations on simple ternary alloys could show that these Co-Al-W based alloys exhibit higher solidus temperatures and show less segregations after casting compared to typical Ni-base superalloys. This leads to the question whether this g/g¢ Co-base superalloys can be regarded as new class of high temperature materials that can compete with or even supersede established Ni-base superalloys.

In the first part of …

Microstructural Analysis And High Temperature Creep Of Mo-9si-8b Alloys With Al And Ge Additions, Peter Kellner, Rainer Völkl, Uwe Glatzel

Beyond Nickel-Based Superalloys II

Refractory metals and their alloys show potential for high temperature applications, due to the increased melting point and creep resistance. Spark plasma sintering technology as well as argon arc melting is used to prepare quaternary and quinternary Mo-9Si-8B-xAl-yGe (x is 0 or 2; y is 0 or 2) samples. Compositions are stated in at.%. All the compositions consist of a Mo solid solution (α-Mo) and two intermetallic phases: Mo₃Si (A15) and Mo₅SiB₂ (T₂). On the one hand, no zirconium is added to the alloys to avoid evaporation of MoO₃ due to the …

Enhanced Oxidation Resistance Of Ti-Rich Mo-Si-B Alloys By Pack-Cementation Process, Camelia Gombola, Daniel Schliephake, Martin Heilmaier, John H. Perepezko

Beyond Nickel-Based Superalloys II

To increase efficiency by higher combustion temperatures of aircraft engines and energy generation, new high temperature materials are inevitable. Mo-Si-B alloys for example satisfy several requirements such as good oxidation and creep resistance. Recently, novel Ti-rich Mo-Si-B alloys have shown an increased creep resistance compared to Ti-free Mo-Si-B alloys by the formation of Ti-silicide precipitates during processing. However, due to the formation of a duplex SiO₂ – TiO₂ oxide layer, where fast inwards diffusion of oxygen takes place, the oxidation resistance is poor.

In this study we show that oxidation resistance of Mo-Si-B-Ti alloys can be enhanced drastically …

Microstructural Stability Of Co-Re-Cr-Ta-C Alloy Strengthened By Tac Precipitates, Debashis Mukherji, Ralph Gilles, Lukas Karge, Pavel Strunz, Přemysl Beran, Joachim Rösler

Beyond Nickel-Based Superalloys II

It is becoming increasingly clear that new materials that can operate at substantially higher temperatures than Ni-base superalloys are needed for future gas turbines. High melting Co-Re-Cr based alloy strengthened by carbides, particularly the MC type carbide, shows promise [1]. A fine dispersion of globular TaC precipitate is exploited for this purpose. Additionally Cr, which is mainly added to improve oxidation resistance, also stabilizes lamellar M₂₃C₆ type Cr carbide. The microstructure of a Co-Re-Cr-Ta-C alloy with the two types of carbides is seen in Fig. 1.

Please click Additional Files below to see the full abstract.

Mo-9si-8b Alloys With Additons Of Zr – Microstructure And Creep Properties, Uwe Glatzel, Christian Hochmuth, Rainer Völkl

Beyond Nickel-Based Superalloys II

Three phase Mo-9Si-8B (at.%) alloys are a prominent example for a potential new high temperature structural material. Due to their high melting point and excellent creep resistance. In this study the effect of Zr addition (0…4 at.%) on the microstructure and creep properties of Mo-9Si-8B (at.%) alloys is investigated. Two powder metallurgical processes, hot isostatic pressing (HIP) and spark plasma sintering (SPS), are used to prepare specimens. The resulting microstructures are examined using SEM and TEM analysis. SPS alloys exhibit smaller grain sizes and fewer oxides compared to the HIP alloys, because of the oxygen availability during HIP. The more …

Microstructure And Creep Resistance Of Ti-Rich Mo + Mo5si3 + Mo5sib2 Alloys, Daniel Schliephake, Martin Heilmaier

Beyond Nickel-Based Superalloys II

New materials are necessary to increase efficiency of power generation and aircraft engines by higher combustion temperatures. Recently, it was found that alloying with high amounts of Ti replaces Mo₃Si by Mo₅Si₃ and stabilizes the phase field Mo + Mo₅Si₃ + Mo₅SiB₂, which could be beneficial for higher oxidation resistance, since Mo₅Si₃ is more oxidation resistant than Mo₃Si. Additional, Ti-rich Mo-Si-B alloys show an increased creep resistance compared to Ti-free Mo-Si-B alloys and a significant reduction in the alloy density. However, using the …

Design Of Gamma-Prime-Strengthened Co-Based Superalloys: Where We Are And Where We Need To Go, Eric A. Lass

Beyond Nickel-Based Superalloys II

Since the first report of a stable two-phase g-g’ (FCC-L12) phase field in ternary Co-Al-W in 2006, there has been significant research effort in developing this new class of Co-based g’-strengthened superalloys for high temperature applications. Much of the focus has been on characterizing and improving high temperature properties such as the g’ solvus temperature, high temperature strength and creep resistance, corrosion and oxidation behavior. Much of this work has been conducted experimentally utilizing the wealth of knowledge of Ni-based superalloys gathered over the last several decades. Efforts into developing effective modeling tools, such as thermodynamic and diffusion databases, have …

Improving The Oxidation Resistance Of Refractory Metals Via Aluminum Diffusion Coatings And Halogen Effect, A.S. Ulrich, M.C. Galetz

Beyond Nickel-Based Superalloys II

Recently, refractory metals and their alloys have received increasing attention for the purpose of substituting Ni-based single crystal superalloys. Compared to commonly used materials, refractory metals have significantly higher melting points while their mechanical properties seem adequate at high temperatures. The main challenge for their application is, that refractory metals show low oxidation resistances at elevated temperatures. Aluminum diffusion layers are promising coatings to suppress harmful oxidation by forming a protective oxide layer. This study deals with the application of such aluminum reservoir layers and with the investigation of their protective properties. Four different unalloyed refractory metals, molybdenum, tantalum, tungsten …

Conference Program, Howard J. Stone

Beyond Nickel-Based Superalloys II

No abstract provided.

E3.Pt – An E3 Portabledyme Model For Portugal, Anett Großmann, Frank Hohmann

International Congress on Environmental Modelling and Software

E3 models are environmentally extended economic models. They are extensively used for impact assessment of energy, climate and resource policies at national and international level. E3 models have proven to be suitable tools for quantifying effects on the economy, environment and energy system. Usually, the structure and documentation of such models are only accessible by the model builders. They are facing the allegation to be a "black box" meaning that only their creators are able to operate and fully understand the model system. Decision makers are often only engaged at the end of the model building process to discuss the …

A Framework For Decision-Making In Cases Of Invasive Species, Peter A. Khaiter, Marina G. Erechtchoukova, Sina Roushan

International Congress on Environmental Modelling and Software

Invasion of nonindigenous species is one of the most pressing global challenges, causing substantial environmental, economic and social harm. Invasion of alien species alters the composition, structure and functioning of invaded ecosystems as well as the services they generated before the invasion. Decisions about the management of invasive cases are inherently difficult because of the multifactorial and multiattribute scope of the problem. In particular, the resilience limits of invaded ecosystems to fully recover original, pre-invaded states remain unclear. To facilitate management efforts, decision-makers and environmental practitioners require a framework integrating relevant knowledge and acting as a supporting expert system. The …

Simulating Spatial Changes In Vegetation-Livestock Interactions Under Different Landscape Structures: A Multi-Agent System Applied To Agro-Pastoral Territories, Mamadou Sané, Jonathan Vayssières, Myriam Grillot, Alassane Bah, Alexandre Ickowicz

International Congress on Environmental Modelling and Software

Free-range and common-grazing ruminants play a major role in the functioning and the provision of ecosystem services by agro- and silvo-pastoral ecosystems in sub-Saharan Africa. To assess how landscape structure affects the nature of environment-herd-services interactions, this paper describes a Multi-Agent System (MAS) that simulates daily herd movements in a dynamic environment. The model is used to study how the overall productivity of an agricultural territory is affected by the spatial organization of its different landscape units. The originality of this model lies in fine representation, in hourly time steps, of a herd’s movements and activities over the seasons depending …

Evapotranspiration Mapping Using Sebal Algorithms To Account For Agricultural Water Uses In The Upper Pangani, Tanzania, Anna Msigwa, Ann Van Griensven, Hans C. Komakech, Boud Verbeiren, Tim Hessels, Wim G. M. Bastiaanssen

International Congress on Environmental Modelling and Software

To make informed decisions, river basin managers requires information on demands and actual usage from different sectors in the basin. Such water use information has to be adequate in terms of quantities used per sector, where and when. However, because of high costs of maintaining equipment for monitoring use, it is very difficult to obtain this information in developing arid and semi- arid areas of Sub-Saharan Africa. The use of proxy method such as calculation of evapotranspiration is proposed as a cheaper means for such data acquisition. Water consumption through crop evapotranspiration (ET) is a major component of water withdrawal, …

Up In The Air: Understanding Vulnerability When Toilets Fly, Amy Krakowka Richmond, Suzanne Pierce, Sethi Gautam

International Congress on Environmental Modelling and Software

Across sub-Saharan Africa, both natural and social factors contribute to household level vulnerability. This case study focuses specifically on Uganda, which has made progress towards meeting the United Nation’s Millennium Development Goals, most notably halving the proportion of the population that is below the poverty line. Despite these impressive achievements, many households remain vulnerable to multiple social and environmental stressors. A better understanding of the drivers of household level vulnerability will assist stakeholders and policy-makers in determining what drives vulnerability at a household level, where vulnerable populations are, and suggest what type of aid to target specific locations to be …

Hindcasting The Dynamics Of An Eastern Mediterranean Marine Ecosystem Under The Impacts Of Multiple And Cumulative Stressors, X. Corrales, M. Coll, E. Ofir, M. Goren, D. Edelist, J. J. Heymans, G. Gal

International Congress on Environmental Modelling and Software

An important challenge for conserving and managing marine ecosystems is to advance our understanding of how multiple human stressors, environmental factors and marine resources interact and influence each other. The ecosystems of the Israeli Mediterranean coast have undergone significant ecological changes in recent decades caused primarily by the introduction of invasive species through the Suez Canal, intense fishing activities and the effects of climate change. An Ecopath model representing the continental shelf of the Israeli Mediterranean coast was calibrated and fitted to the available time series from early 1990’s to 2010 using the Ecosim temporal dynamic modeling approach. The model …

Application Of The Swat Model To Investigate Surface Runoff And Nitrate Flux Towards The Mediterranean Sea: Case Of The Tafna Catchment (North-West Of Africa), Amin Zettam, Amina Taleb, Sabine Sauvage, José Miguel Sanchez-Perez, Laurie Boithias, Nouria Belaidi

International Congress on Environmental Modelling and Software

Water in North-West of Africa is an increasingly valuable resource due to high competition between agriculture, industry and drinking water supply, accentuated by frequent drought conditions in a semi-arid climate. For a few decades, the demographic explosion, the development of agriculture and industry, and the building of water infrastructures (dams) have modified the water fluxes and the biogeochemical cycle of nitrogen towards an increased production of nitrates in waters. The objectives of this study are to propose a modelling approach to quantify the contribution of the Tafna coastal watershed (North-West of Africa) to the flux of nitrates into the Mediterranean …