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Full-Text Articles in Engineering

The Optimized Synthesis Of Copper Nanowire For High-Quality And Fabrication Of Core-Shell Nanowire, Suhyun Lee Dec 2019

The Optimized Synthesis Of Copper Nanowire For High-Quality And Fabrication Of Core-Shell Nanowire, Suhyun Lee

Dissertations and Theses

Flexible electronics are the promising technology for prospective application in foldable phones. Currently, indium tin oxide (ITO) has been widely used for electronic devices including flat-panel display. However, it is brittle and expensive. Metal nanowires are considered as alternative materials. Among various metal nanowires, copper nanowires are attractive because of its high electrical conductivity, better flexibility, and low cost compared with ITO. However, copper nanowires are very prone to oxidize, which causes subsequent degradation of electrical conductivity. Due to this oxidation issue, core-shell structure nanowires, which are formed silver shell having high conductivity and low resistivity on the surfaces of ...


Early Detection Of Corrosion Via Hydrogel-Based Spectroelectrochemical Sensors, Capri Ann Price Nov 2018

Early Detection Of Corrosion Via Hydrogel-Based Spectroelectrochemical Sensors, Capri Ann Price

Dissertations and Theses

The backbone of the industrialized world is comprised of refined, zerovalent metal, a material which thermodynamically favors an oxidative return to more chemically stable states. There are many methods used to slow or delay this process, such as protective coatings, sacrificial anodes, and alloys, but no method can entirely prevent corrosion. This body of work instead proposes detecting the earliest chemical markers of corrosion: that is, metal ions as they solubilize from a metal surface. Such information would allow maintenance personnel to make informed decisions about the necessity or lack thereof of preventive maintenance, and intervene before advanced damage has ...


Novel 2d Structure Nanomaterials Synthesis And Ir Absorption, Suming Wang Aug 2018

Novel 2d Structure Nanomaterials Synthesis And Ir Absorption, Suming Wang

Dissertations and Theses

Nanomaterials have gained much attention as in energy storage application for its unique electrical properties. Many research groups have developed various methods to fabricate nanomaterials for various applications. However, there exists much possibilities of developing cost-effective methods for nanomaterial fabrication. No one has studied using natural organic compound A as solution base for wet process nanomaterial synthesis.

In this study, a new method of fabricating two-dimensional structure nanomaterials is proposed. This method is applicable for multiple metal elements such as copper oxide, copper hydroxide, and iron oxide. The two dimensional structure nanomaterials have prestige properties because of their large surface ...


Microstructure And Mechanical Properties Of Additive Manufacturing Titanium Alloys After Thermal Processing, Ahmet Alptug Tanrikulu Dec 2017

Microstructure And Mechanical Properties Of Additive Manufacturing Titanium Alloys After Thermal Processing, Ahmet Alptug Tanrikulu

Dissertations and Theses

Titanium alloys are widely used for aerospace and biomaterial applications since their high specific strength, and high corrosion resistivity. Besides these properties, titanium is an excellent biocompatible material widely used for internal body implants. Because the products have complex geometries in both applications, Additive Manufacturing (AM) methods have been recently applied for production. AM methods can process a direct 3-D shape of the final product, decrease total production time and cost. However, high residual stress of the final product limits the application of AM components, especially the ones that are exposed to cyclic loading. In the present study, the initial ...


Building Energy Model Calibration For Retrofit Decision Making, Nicolas R. Johnson Mar 2017

Building Energy Model Calibration For Retrofit Decision Making, Nicolas R. Johnson

Dissertations and Theses

Accommodating the continued increase in energy demand in the face of global climate change has been a worldwide concern. With buildings in the US consuming nearly 40% of national energy, a concerted effort must be given to reduce building energy consumption. As new buildings continue to improve their efficiency through more restrictive energy codes, the other 76.9 billion square feet of current building stock falls further behind. The rate at which current buildings are being retrofit is not enough and better tools are needed to access the benefits of retrofits and the uncertainties associated with them. This study proposes ...


One-Dimensional Nanostructure And Sensing Applications: Tin Dioxide Nanowires And Carbon Nanotubes, Hoang Anh Tran Feb 2016

One-Dimensional Nanostructure And Sensing Applications: Tin Dioxide Nanowires And Carbon Nanotubes, Hoang Anh Tran

Dissertations and Theses

The key challenge for a nanomaterial based sensor is how to synthesize in bulk quantity and fabricate an actual device with insightful understanding of operational mechanisms during performance. I report here effective, controllable methods that exploit the concepts of the "green approach" to synthesize two different one-dimensional nanostructures, including tin oxide nanowires and carbon nanotubes. The syntheses are followed by product characterization and sensing device fabrications as well as sensor performance understanding at the molecular level. Sensor-analyte response and recovery kinetics are also presented.

The first part of the thesis describes bulk-scale synthesis and characterization of tin oxide nanowires by ...


Constant Interface Temperature Reliability Assessment Method: An Alternative Method For Testing Thermal Interface Material In Products, Christian Amoah-Kusi May 2015

Constant Interface Temperature Reliability Assessment Method: An Alternative Method For Testing Thermal Interface Material In Products, Christian Amoah-Kusi

Dissertations and Theses

As electronic packages and their thermal solutions become more complex the reliability margins in the thermal solutions diminish and become less tolerant to errors in reliability predictions. The current method of thermally stress testing thermal solutions can be over or under predicting end of life thermal performance. Benefits of accurate testing and modeling are improved silicon yield in manufacturing, improved performance, lower cost thermal solutions, and shortened test times.

The current method of thermally stress testing is to place the entire unit in an elevated isothermal temperature and periodically measure thermal performance. Isothermally aging is not an accurate representation of ...


Measuring The Effect Of Vegetated Roofs On The Performance Of Photovoltaic Panels In Combined Systems, Hamid Hawi Kadham Ogaili May 2015

Measuring The Effect Of Vegetated Roofs On The Performance Of Photovoltaic Panels In Combined Systems, Hamid Hawi Kadham Ogaili

Dissertations and Theses

Recent studies suggest that integration of photovoltaic panels with green roofs may improve the performance of both. While vegetation may provide a benefit by reducing the net radiation load on the underside of the photovoltaic (PV) panels, it may also affect convective cooling of panels, and consequently, panel efficiency. Both effects likely diminish with the height of the PV panel above the roof, although placing PV panels too close to the vegetation increases the risk of the plants growing over the edges of, and shading the PV panel. There is a gap in the literature with respect to evaluating these ...


Experimental Investigation Of Lateral Cyclic Behavior Of Wood-Based Screen-Grid Insulated Concrete Form Walls, John Stuart Garth Jun 2014

Experimental Investigation Of Lateral Cyclic Behavior Of Wood-Based Screen-Grid Insulated Concrete Form Walls, John Stuart Garth

Dissertations and Theses

Insulated concrete forms (ICFs) are green building components that are primarily used for residential wall construction. Unlike most polystyrene based ICF variants, the Faswall ICFs used in these experiments were significantly denser because they were made from recycled wood particles and cement. The current design approach for structures constructed with this type of wall form only allows the designer to consider the contribution of the reinforced concrete cores. Previous research has shown that this approach may be conservative. This project experimentally evaluated the lateral structural response of these types of grid ICF walls under increasing amplitude of in-plane cyclic loading ...


Stress Analysis For Chip Scale Packages With Embedded Active Devices Under Thermal Cycling, Hyunwook Yeo Jun 2014

Stress Analysis For Chip Scale Packages With Embedded Active Devices Under Thermal Cycling, Hyunwook Yeo

Dissertations and Theses

One of the main challenges in the electronics manufacturing and packaging development is how to integrate more functions inside the same or even smaller size. To meet the demand for higher integration, the interest toward passive and active component embedding has been increasing during the past few years. One of the main reasons for the growing interest toward embedded active components, in addition to demand for higher packaging density, is the need for better electrical performance of the component assemblies. However, it is little known how embedded IC and passives affect the reliability of IC packaging.

Solder joints have been ...


Solid State Pre-Formed Electronics Adhesive (Spea), Alexander Randon Cope Sep 2013

Solid State Pre-Formed Electronics Adhesive (Spea), Alexander Randon Cope

Dissertations and Theses

In mobile and handheld consumer electronic markets, product use conditions drive the requirement for mechanical strength and device durability. The majority of relatively large form factor electronic components in a laptop, mobile internet device, PDA, or mobile phone use an adhesive as a stiffener to help protect the component from physical stresses imposed by daily wear and tear. Described herein is an innovative solution referred to as Solid State Pre-Formed Electronics Adhesive (SPEA), which enables a decrease in circuit board manufacturing throughput time while increasing mechanical durability with a consistent and characterized adhesive application process.

Today, many consumer electronic ODM ...


Capillarity-Driven Droplet Ejection, Andrew Paul Wollman Jun 2012

Capillarity-Driven Droplet Ejection, Andrew Paul Wollman

Dissertations and Theses

Drop Towers provide brief terrestrial access to microgravity environments. When used for capillary fluidics research, a drop tower allows for unique control over an experiment's initial conditions, which enables, enhances, or otherwise improves the study of capillary phenomena at significantly larger length scales than can normally be achieved on the ground. This thesis provides a historical context for the introduction of a new, highly accessible, 2.1s tower design used for capillary research and presents a variety of demonstrative experimental results for purely capillarity-driven flows leading to bubble ingestion, sinking flows, multiphase flows, and droplet ejections. The focus of ...


Fundamental Properties Of Functional Zinc Oxide Nanowires Obtained By Electrochemical Method And Their Device Applications, Athavan Nadarajah Jan 2012

Fundamental Properties Of Functional Zinc Oxide Nanowires Obtained By Electrochemical Method And Their Device Applications, Athavan Nadarajah

Dissertations and Theses

We report on the fundamental properties and device applications of semiconductor nanoparticles. ZnO nanowires and CdSe quantum dots were used, prepared, characterized, and assembled into novel light-emitting diodes and solar cells. ZnO nanowire films were grown electrochemically using aqueous soluble chloride-based electrolytes as precursors at temperatures below 90° C. Dopants were added to the electrolyte in the form of chloride compounds, which are AlCl3, CoCl2, CuCl2, and MnCl2. The optical, magnetic, and structural properties of undoped and transition-metal-ion doped ZnO nanowires were explored. Our results indicate that the as-grown nanowire structures have considerable internal strain, resulting ...


A Feasibility Study Of Model-Based Natural Ventilation Control In A Midrise Student Dormitory Building, Steven James Gross Jan 2011

A Feasibility Study Of Model-Based Natural Ventilation Control In A Midrise Student Dormitory Building, Steven James Gross

Dissertations and Theses

Past research has shown that natural ventilation can be used to satisfy upwards of 98% of the yearly cooling demand when utilized in the appropriate climate zone. Yet widespread implementation of natural ventilation has been limited in practice. This delay in market adoption is mainly due to lack of effective and reliable control. Historically, control of natural ventilation was left to the occupant (i.e. they are responsible for opening and closing their windows) because occupants are more readily satisfied when given control of the indoor environment. This strategy has been shown to be effective during summer months, but can ...


Phase Change Materials As A Thermal Storage Device For Passive Houses, Kevin Ryan Campbell Jan 2011

Phase Change Materials As A Thermal Storage Device For Passive Houses, Kevin Ryan Campbell

Dissertations and Theses

This study describes a simulation-based approach for informing the incorporation of Phase Change Materials (PCMs) in buildings designed to the "Passive House" standard. PCMs provide a minimally invasive method of adding thermal mass to a building, thus mitigating overheating events. Phase change transition temperature, quantity, and location of PCM were all considered while incrementally adding PCM to Passive House simulation models in multiple climate zones across the United States. Whole building energy simulations were performed using EnergyPlus from the US Department of Energy. A prototypical Passive House with a 1500 Watt electric heater and no mechanical cooling was modeled. The ...


The Influence Of Halloysite Content On The Shear Strength Of Kaolinite, Reka Katalin Gabor Jan 1981

The Influence Of Halloysite Content On The Shear Strength Of Kaolinite, Reka Katalin Gabor

Dissertations and Theses

The objective of this thesis is to determine the relative shear strengths of halloysite, kaolinite, synthetic mixtures, and local soils, to investigate the influence of halloysite content on the shear strength of kaolinite, and to explore the possibility that the strength properties of soil clays might be controlled by the relative content of their component minerals.


A Feasibility Analysis Of A Directly Sun-Pumped Carbon Dioxide Laser In Space, Seiichi Morimoto Jan 1979

A Feasibility Analysis Of A Directly Sun-Pumped Carbon Dioxide Laser In Space, Seiichi Morimoto

Dissertations and Theses

The possibility of using sunlight to pump a CW carbon dioxide laser has been analyzed. Such a laser could be of interest for such applications as space communication and power transmission. In order to optically pump CO2 using sunlight, the intense vibrational-rotational absorption bands of CO2 in the 4.3 micron spectral region would have to be utilized. The total pumping power from sunlight can be calculated from the known data of the solar spectral irradiance outside the atmosphere and the infrared absorption by carbon dioxide at 4.3 microns. The pumping power is proportional to the collector ...


Assessment Of Feasibility Of Proposed Bolted Connections For Tubular Structures, John Henry Tausch Nov 1977

Assessment Of Feasibility Of Proposed Bolted Connections For Tubular Structures, John Henry Tausch

Dissertations and Theses

The search for new and additional sources of energy -- from sun, wind, waves, and ocean currents -- is necessitating the development of structures in the open environment of the oceans as well as on land. The advantages of round or tubular members for use in such structures are shown; and to avoid the uncertainties of welded joints, two bolted connections are proposed and their feasibility explored.


An Automatic Rinse Tank Controller For Industrial Applications, Aliasghar Emami Jan 1974

An Automatic Rinse Tank Controller For Industrial Applications, Aliasghar Emami

Dissertations and Theses

This thesis describes an automatic Rinse Tank Control System used in detection and removal of contaminating agents from industrial plating rinse tanks. It automatically monitors the purity of the rinse water in sixteen separate rinse tanks, and permits fresh water to enter the tanks only when the conductivity of the rinse water in each tank exceeds a predetermined level. Its use will result in large savings in consumption of fresh water and the subsequent reduction in discharge of effluent to the treatment plants.


Recent Developments In The Use Of Precast Concrete Units For Buildings In The United States And Iran, Khosrow Ebadi Farshchi Aug 1973

Recent Developments In The Use Of Precast Concrete Units For Buildings In The United States And Iran, Khosrow Ebadi Farshchi

Dissertations and Theses

The object of this study was to investigate the recent developments in the use of precast prestressed concrete members for buildings in the United States and Iran. In the United States, the study was concerned with developments in the usage of members such as slabs, wall panels, beams and columns. The latest technical and engineering reports, along with personal interviews, were used, and a number of case studies were conducted on recently built structures. The author also studied the newest developments in the precast concrete industry in Iran. A questionnaire was formulated in both Persian (native language of Iran) and ...


Comparative Study Of Lightweight And Normal Weight Concrete In Flexure, Mohammad Zareh Jan 1971

Comparative Study Of Lightweight And Normal Weight Concrete In Flexure, Mohammad Zareh

Dissertations and Theses

This investigation represents a comparative study of the flexural behavior of lightweight and normal weight concrete. Both theoretical and experimental moment-curvature characteristics of the tested specimens were used to study the flexural behavior. A generalized computer program to determine the moment-curvature relationships of a singly reinforced rectangular concrete beam was developed. For this limited study it was observed that lightweight concrete beams when compared to normal concrete beams achieve comparable moment capacity (about 92% of normal weight concrete) but exhibit higher deflections (about 40% more than normal weight concrete).


Direct Design Of A Portal Frame, Angel Fajardo Ugaz Jan 1971

Direct Design Of A Portal Frame, Angel Fajardo Ugaz

Dissertations and Theses

This investigation was undertaken to develop plastic design aids to be used in the direct design of optimum frames. It uses the concept of minimum weight of plastically designed steel frames, and the concept of linear programming to obtain general solutions. Among the special characteristics of this study are: A. The integration of both gravity and combined loading conditions into one linear programming problem. B. The application of the revised simplex method to the dual of a parametric original problem. C. The application of A and B above in the development of design aids for the optimum design of symmetrical ...