Engineering Commons^™

Analysis And Mitigation Of Carrier Frequency Offset For Uplink Of Ofdma, Abhishek R. Panchal

Theses

Orthogonal Frequency Division Multiplexing (OFDM) is being used in many wireless standards because of its immunity to multipath fading, high spectral efficiency and simple implementation, making it suitable for high data rate multimedia wireless applications. One of the significant drawbacks of the OFDM is its sensitivity to Carrier Frequency Offset (CFO). CFO causes Inter Carrier Interference (ICI) between subcarriers and Multiple User Interference (MUI) at Uplink between different users. ICI and MUI at uplink cause significant degradation in the performance of the receiver, therefore, to improve the receiver performance up to acceptable level, compensation of the CFO becomes necessary.

In …

Soy Protein-Poly (L-Lactic Acid) Blend Nanofibers For Drug Delivery Of Nardostachys Jatamansi, Swetha Tiwari

Theses

Electrospun nanofibers when nanofi bers are impregnated with drugs play a significant role in drug delivery. Nanomedical approaches to drug delivery focus on developing nanoscale particles or molecules to improve the bioavailab ility of a drug.

Biodegradable nanofibers were developed using Poly (L – lactic acid) and Soy protein for the delivery of an ayurvedic drug, Nardostachys jatamansi. A weighed quantity of powdered drug – Nardostachys Jatamansi was subjected to Soxhlet extraction using water and ethanol in equal quantities. Various blends of the drug extract and soy protein solution are prepared and mixed in Poly (L-lactic acid). Nanofibers of …

Hydrogen Storage In Pt/Carbon Nanotube Sheets, An-Yu Ma

Theses

Three types of self-assembled carbon nanotube (CNT) sheets, for example, carboxylic functionalized multi-walled CNTs (MWNTs-COOH), pure multi-walled CNTs (MWNTs), and pure single-walled CNTs (SWNTs), were prepared as substrates by ambient environment vacuum filtration of suspensions of the nanotubes. To enhance hydrogen storage on the CNTs, platinum particles were deposited on the three types of CNT sheets using two processes: electrodeposition (ED) using a DC power source and electrochemical deposition under cyclic voltammetry (CV). To verify platinum deposition on the surface of the CNT sheets, a Scanning Electron Microscope (SEM) was used to obtain images, and Energy Dispersive X-ray (EDX) spectroscopy …

Dynamic Friction: Measurement And Results, Yanal Jij

Theses

Friction has been known as a phenomenon since Leonardo da Vinci era. From that time and through the last four centuries, scientists tried to understand this phenomenon in an effort to overcome its undesired side effects which include energy loss, parts wearing, and errors in control systems. Much has been achieved in studying friction and many experiments have been conducted in this field. These experiments resulted in a mounting evidence that friction is a dynamic phenomenon.

This thesis presents an apparatus that measures dynamic friction in linear motion and the results obtained using this apparatus. The apparatus consists of a …

Alendronate Treatment Elicits A Reduction In Fatigue-Life Of Canine Cortical Bone, Joseph Ryan Geissler

Theses

Bone serves contradictory needs; bone must be strong yet light, and stiff yet flexible. At the tissue level bone material withstands cyclic loading without failing by dissipating energy via the formation and accumulation of microdamage. Proper removal of this damage in exchange for fresh tissue is vital to bone maintenance, and is achieved through a remodeling process. Imbalanced remodeling leads to osteoporotic fractures. Bisphosphonate drugs are proven to reduce fracture risk. However, the long-term effects of bisphosphonates on tissue-level properties are unknown. This study characterized the fatigue-life of cortical bone tissue after bisphosphonate treatment with alendronate (Aln). 1 1th ribs …

Preparation Of Different Polyamide Nanofiltration Membranes By Interfacial Polymerization And The Effect Of Post-Polymerization Treatment On Separation Performance, Yu Qin

Theses

Interfacial polymerization (IP) is a powerful technique for fabrication of thin film composite (TFC) membranes. In this study, polyamide nanofiltration (NF) composite membranes ware prepared by interfacial polymerization of polyethylenimine (PEI) or m-phenylene diamine (MPD) with isophthaloyl dichloride (IPD) on the surface of a porous polyethersulfone (PES) support. Concentrations of monomer reactants for this reaction were decided by equivalent weight ratio. A standard IP procedure was applied to successfully coat PES flat films. After preparation, three different post-polymerization treatments were employed and one optimal treatment was proven after membrane testing.

The TFC flat film membranes were characterized by nanofiltration of …

Evanescent Field Coupling Between Two Parallel Close Contact Sms Fiber Structures, Qiang Wu, Youqiao Ma, Jinhui Yuan, Yuliya Semenova, Pengfei Wang, Chongxiu Yu, Gerald Farrell

Articles

We proposed a novel optical coupling technique based on two parallel singlemode-multimode- singlemode (SMS) fiber structures. This technique utilizes one SMS structure to excite multiple cladding modes within an output singlemode fiber. The excited multiple cladding modes will be coupled to the input SMF in the second SMS structure by placing the two SMS fiber structures in parallel and in close contact each other. The coupled cladding modes will be re-coupled to a guided core mode by the second SMS fiber structure. Theoretical analysis for such technique was provided and experimentally we have achieved a pass band spectral response with …

Second Generation Data-Logging System For Long-Duration Field Measurement Of Vibration Exposure And Grip Force, Robert H. Knapp Iii

Master's Theses

Millions of United States workers are exposed to vibration at their job, whether it is from a power tool that causes hand and arm vibration or from heavy machinery. These vibrations are known to result in physical disorders such as Hand-Arm Vibration Syndrome, which can be debilitating to the point where workers can no longer do their job effectively. Research groups have taken an interest in finding what vibration characteristics are most harmful and choose to record vibration information using data-logging devices. Often, many devices, whether they are commercial or custom-built devices, use frequency weightings and full day estimations to …

Design And Analysis Of Optical Networking Protocols, Rabindra Ghimire

Theses and Dissertations

The Internet has emerged as one of the most widely used infrastructures that supports multiple applications with varying service requirements. The communication infrastructure of the Internet has evolved into a hybrid architecture consisting of, for example, wireless, wireline, optical, and satellite networks, among others. Several challenges arise in offering end-to-end services over such a hybrid network, some of which being ensuring reliability, providing for recovery in the wake of failures, and offering services with quality of service (QoS). Various protocols have been developed to support QoS over the internet. The hybrid architecture supports multilayer network allowing multiple IP protocols to …

Novel Antennas Based On Innovations In Nano-Scale And Metamaterial Structures, Taha A. Elwi

Theses and Dissertations

This dissertation focuses on the use of nano-scale and metamaterial structures for modern antenna applications including wearable devices, Global Positioning Systems, and self-powered wearable systems. Conductive composites, thin films, and array crystallography are nanostructural materials with superior properties that can be applied to printed electronic circuits, antennas, and optoelectronic devices. The feasibility of using conductive multi-walled carbon nanotube composites for printing patch antennas operating in the microwave range is demonstrated for the first time. A flexible meander sinusoidal patch based on a thin film of copper is presented for wearable medical telemetry devices. The effects of twisting and bending on …

A Design Basis For Composite Cascode Stages Operating In The Subthreshold/Weak Inversion Regions, Taylor Matt Waddel

Theses and Dissertations

Composite cascode stages have been used in operational amplifier designs to achieve ultra-high gain at very low power. The flexibility and simplicity of the stage makes it an appealing choice for low power op-amp designs. Op-amp design using the composite cascode stage is often made more difficult through the lack of a design process. A design process to aid in the selection of the MOSFET dimensions is provided in this thesis. This process includes a table-based method for selection of the widths and lengths of the MOSFETs used in the composite cascode stage. Equations are also derived for the gain, …

Slides: Unconventional Gas And Oil – Potential Air Emissions, John Imse

Air Quality Impacts from Oil and Gas Development (January 27)

Presenter: John Imse, Hydrogeologist, ENVIRON International Corporation presents an overview of the current methods for developing a shale play and the typical site operations

10 slides

Slides: Air Monitoring And Litigation Update, John Jacus

Air Quality Impacts from Oil and Gas Development (January 27)

Presenter: John Jacus, Partner, Davis Graham & Stubbs LLP, reviews recent litigation aimed at oil and gas development activities with respect to air emissions impacts, and also several recent and ongoing studies and ambient monitoring efforts focused upon air emissions from oil and gas activities

23 slides

Slides: Air Quality - Oil And Gas Development, Paul R. Tourangeau

Air Quality Impacts from Oil and Gas Development (January 27)

Presenter: Paul Tourangeau, Assistant General Counsel, DCP Midstream, LP and former Director, Colorado Air Pollution Control Division, addresses regulatory requirements and policies related to air emissions from the oil and gas sector, including recent and current initiatives at the state and federal level

8 slides

Slides: Hydrofracking: Air Issues And Community Exposure, Debra A. Kaden

Air Quality Impacts from Oil and Gas Development (January 27)

Presenter: Debra Kaden, Ph.D., Toxicologist, ENVIRON International Corporation, discusses air concentrations of chemicals of potential health concern surrounding oil and gas development activities, as well as temporal and spatial patterns of these chemicals in the ambient environment. Such information is necessary to evaluate possible health impacts of the drilling process on air in surrounding communities.

19 slides

Agenda: Air Quality Impacts From Oil And Gas Development, University Of Colorado Boulder. Natural Resources Law Center

Air Quality Impacts from Oil and Gas Development (January 27)

Oil and gas development and hydraulic fracturing have received enormous attention over the past few years, and most of that attention has focused on the potential impacts of such development on water quality. However, the potential impacts on air quality from oil and gas development have received far less public and media attention and discussion. This two-hour program will assess the current scientific knowledge, regulatory requirements and policies regarding the impacts on air quality from oil and gas development and will address current initiatives at the state and national levels to further regulate and control those impacts.

An All-Silicon Passive Optical Diode, Li Fan, Jian Wang, Leo T. Varghese, Hao Shen, Ben Niu, Yi Xuan, Andrew M. Weiner, Minghao Qi

Birck and NCN Publications

A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

Size Effects In Niti From Density Functional Theory Calculations, Karthik Guda Vishnu, Alejandro Strachan

Birck and NCN Publications

We use density functional theory to characterize how size affects the relative stability of thin NiTi slabs of different crystal structures and its implication on the martensitic phase transition that governs shape memory. We calculate the surface energies of B2' phase (austenite), B19 (orthorhombic), B19' (martensite), and a body-centered orthorhombic phase, the theoretically predicted ground state. We find that (110)(B2) surfaces with in-plane atomic displacements stabilize the austenite phase with respect to B19' and BCO; thus, slabs with such orientations are predicted to exhibit a decrease in martensite transition temperature with decreasing thickness. Our calculations predict a critical thickness of …

A Nano-Cheese-Cutter To Directly Measure Interfacial Adhesion Of Freestanding Nano-Fibers, Xin Wang, Johnny F. Najem, Shing Chung Josh Wong, Kai-Tak Wan

Mechanical Engineering Faculty Research

A nano-cheese-cutter is fabricated to directly measure the adhesion between two freestanding nano-fibers. A single electrospun fiber is attached to the free end of an atomic force microscope cantilever, while a similar fiber is similarly prepared on a mica substrate in an orthogonal direction. External load is applied to deform the two fibers into complementary V-shapes, and the force measurement allows the elastic modulus to be determined. At a critical tensile load, “pull-off” occurs when the adhering fibers spontaneously detach from each other, yielding the interfacial adhesion energy. Loading-unloading cycles are performed to investigate repeated adhesion-detachment and surface degradation.

Investigation Of A New Material For Heart Valve Tissue Engineering, Claire Brougham, Nian Shen, Allison Cudsworth, Thomas Flanagan, Stefan Jockenhoevel, Fergal O'Brien

Conference Papers

No abstract provided.

Resolving Structure And Mechanical Properties At The Nanoscale Of Viruses With Frequency Modulation Atomic Force Microscopy, David Martinez-Martin, Carolina Carrasco, Mercedes Hernando-Perez, Pedro J. De Pablo, Julio Gomez-Herrero, Rebeca Perez, Mauricio G. Mateu, Jose L. Carrascosa, Daniel Kiracofe, John Melcher, Arvind Raman

Birck and NCN Publications

Structural Biology (SB) techniques are particularly successful in solving virus structures. Taking advantage of the symmetries, a heavy averaging on the data of a large number of specimens, results in an accurate determination of the structure of the sample. However, these techniques do not provide true single molecule information of viruses in physiological conditions. To answer many fundamental questions about the quickly expanding physical virology it is important to develop techniques with the capability to reach nanometer scale resolution on both structure and physical properties of individual molecules in physiological conditions. Atomic force microscopy (AFM) fulfills these requirements providing images …

Application Of Image Processing To Track Twin Boundary Motion In Magnetic Shape Memory Alloys, Adrian Rothenbuhler, Elisa Barney Smith, Peter Müllner

Electrical and Computer Engineering Faculty Publications and Presentations

Materials scientists make use of image processing tools more and more as technology advances and the data volume that needs to be analyzed increases. We propose a method to optically measure magnetic eld induced strain (MFIS) as well as twin boundary movement in Ni₂MnGa single crystal shape memory alloys to facilitate spatially resolved tracking of deformation. Current magneto-mechanical experiments used to measure MFIS can measure strain only in one direction and do not provide information about the movement of individual twin boundaries. A sequence of images captured from a high resolution camera is analyzed by a boundary detection …

Estimation Of Performance Indices For The Planning Of Sustainable Transportation Systems, Pankaj Maheshwari, Alexander Paz, Pushkin Kachroo

Graduate Publications & Presentations

What is sustainable transportation system?

Fulfill the needs of current generations without compromising the ability of future generations

Utilize resources without compromising their health and productivity Leads to development that improves quality of life

Assimilate economic, ecological, social, and bio-physical components of resource ecosystems

Minimize the use of renewable and non-renewable resources, provide affordability and equity between generations

A Global Assessment Of The Water Footprint Of Farm Animal Products, Mesfin Mekonnen, Arjen Y. Hoekstra

Daugherty Water for Food Global Institute: Faculty Publications

The increase in the consumption of animal products is likely to put further pressure on the world’s freshwater resources. This paper provides a comprehensive account of the water footprint of animal products, considering different production systems and feed composition per animal type and country. Nearly one-third of the total water footprint of agriculture in the world is related to the production of animal products. The water footprint of any animal product is larger than the water footprint of crop products with equivalent nutritional value. The average water footprint per calorie for beef is 20 times larger than for cereals and …

Ceas E-News 01.24.2012, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Engineers Week, TAPPI Award Winner, Career Fair, Monroe-Brown Internships

Canopy Radiation Transmission For An Energy Balance Snowmelt Model, Vinod Mahat, David G. Tarboton

Civil and Environmental Engineering Faculty Publications

To better estimate the radiation energy within and beneath the forest canopy for energy balance snowmelt models, a two stream radiation transfer model that explicitly accounts for canopy scattering, absorption and reflection was developed. Upward and downward radiation streams represented by two differential equations using a single path assumption were solved analytically to approximate the radiation transmitted through or reflected by the canopy with multiple scattering. This approximation results in an exponential decrease of radiation intensity with canopy depth, similar to Beer's law for a deep canopy. The solution for a finite canopy is obtained by applying recursive superposition of …

Hydrogen Silsesquioxane (Hsq) For Use In Nano Imprint Lithography, Nathaniel Clark

Theses and Dissertations

Innovations are being researched, using materials science, in the areas of sub- 100nm feature production. Current methods such as electron beam lithography (EBL), Extreme Ultra-Violet Lithography (EUV), and Nano-imprint lithography (NIL) are currently being studied to deliver a high throughput, low-cost process, and high field size for nano-lithography. EBL is a technique which can generate very small features (sub-10nm) but is a serial process which has undesirable time constraints. EUV is the latest generation of photo-lithography which can produce 35nm features, but has a limited area of exposure. NIL is a high resolution high throughput process, but still has time …

Using Hard Macros To Accelerate Fpga Compilation For Xilinx Fpgas, Christopher Michael Lavin

Theses and Dissertations

Field programmable gate arrays (FPGAs) offer an attractive compute platform because of their highly parallel and customizable nature in addition to the potential of being reconfigurable to any almost any desired circuit. However, compilation time (the time it takes to convert user design input into a functional implementation on the FPGA) has been a growing problem and is stifling designer productivity. This dissertation presents a new approach to FPGA compilation that more closely follows the software compilation model than that of the application specific integrated circuit (ASIC). Instead of re-compiling every module in the design for each invocation of the …

Carbon Dioxide Transfer Through Hollow Fiber Membranes, Pavlo Kostetskyy

Theses and Dissertations

Studies on absorption of CO2 into an aqueous solution using hydrophobic microporous hollow fiber membranes (HFM's) were performed. The use of HFM's for CO2 transfer could significantly improve the biomass growth rate in a photobioreactor for algal biofuel production. The membrane modules were operated in a sealed-end, parallel flow configuration. Several modules were constructed that ranged in interfacial surface area from 466 to 1397 m2/m3. The mass transfer coefficients were calculated based on a model of the system that included a prediction of the internal axial gas concentrations within the fiber lumen. This model was validated by measuring bulk gas …

Modeling Groundwater Levels On The Calera Aquifer Region In Central Mexico Using Modflow, Jairo E. Hernández, Prasanna H. Gowda, Terry A. Howell, Jean L. Steiner, Francisco Mojarro, Ernesto P. Núñez, José R. Avila

Civil Engineering Faculty Publications and Presentations

A conceptual model for the Calera Aquifer has been created to represent the aquifer system beneath the Calera Aquifer Region (CAR) in the State of Zacatecas, Mexico. The CAR area was uniformly partitioned into a 500 X 500 m grid generating a high resolution model that represented the natural boundaries of the aquifer. A computer model was calibrated and validated to verify output from the model corresponding to situations that matched the historical aquifer performance. Predicted groundwater levels were compared with measured data collected from nine observation wells between 1954 and 2004 to evaluate model performance. The main objective of …