Engineering Commons^™

Simulations Of Vapor/Ice Dynamics In A Freeze-Dryer Condenser, Arnab Ganguly, A Venkattraman, Alina A. Alexeenko

School of Aeronautics and Astronautics Faculty Publications

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. Key performance characteristics of a freeze-dryer condenser are largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlow (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor molecular model is applied in the DSMC …

Model Uncertainties In A Sharp Leading-Edge Hypersonic Boundary Layer, Marat Kulakhmetov, Alina A. Alexeenko

School of Aeronautics and Astronautics Faculty Publications

The effects of uncertainties in the gas-surface interaction and intermolecular interaction models on the hypersonic boundary layer development are investigated using the nonintrusive generalized polynomial chaos method. In particular, uncertainties in the surface shear stress, normal stress, heat flux, flowfield temperature and density resulting from uncertain viscosity exponent, surface temperature and accommodation coefficient are considered. The polynomial chaos expansion approach is used to reconstruct the probability density function, calculate mean, standard deviation and skewness of the dependent variables from the DSMC calculations. The uncertainty analysis shows that surface fluxes and flowfields in the hypersonic boundary layer are more sensitive to …

Unsteady 3d Rarefied Flow Solver Based On Boltzmann-Esbgk Model Kinetic Equations, Sruti Chigullapalli, Alina A. Alexeenko

School of Aeronautics and Astronautics Faculty Publications

Formulation and verification of unsteady rarefied flow solver based on BoltzmannESBGK equations in arbitrary three-dimensional geometries is presented. The solver is based on the finite volume method in physical space and the discrete ordinate method in velocity space with an implicit time discretization. Verification is carried out for an unsteady approach to equilibrium, a steady one-dimensional Couette flow and a two-dimensional quasi-steady gas damping problem. Finally, the application of the full 3D parallel solver is considered to simulate unsteady microscale gas damping in a micro-electro-mechanical system switch.

Doctoral Students As Course Instructors: Three Engineering Teaching Assistants' Socialization Experiences, Irene Mena, Heidi Diefes-Dux, Brenda Capobianco

School of Engineering Education Graduate Student Series

The purpose of this study was to explore and understand the types of socialization experiences that result from engineering graduate teaching assistants‟ (TAs) roles as course instructors. Socialization refers to an individual‟s process of becoming a part of a group. In the context of doctoral education, socialization can be a complex area to study, largely because there are many roles and groups for which graduate students can be socialized.

Using situated learning, more specifically the communities of practice literature, as the theoretical framework, this study looked at how three doctoral engineering TAs, with experience as course instructors, become members of …

Exploring The Motivations For Migration Among Engineering Students, Ida Ngambeki, Demetra Evangelou Dr, Matthew Ohland, George Dante Ricco

School of Engineering Education Graduate Student Series

Students often graduate from a major other than that in which they first enrolled. A large proportion of this migration happens within engineering with students moving from one discipline of engineering to another. This movement between disciplines sometimes happens several times. While there has been extensive examination of why students leave engineering,very little research has looked into why students leave one engineering discipline for another.Longitudinal data collected from several engineering colleges has shown that there are definite trends within the movement of engineering students.This study examines the reasons for some of these trends using a unique approach which combines both …

Design Concepts Of Terahertz Quantum Cascade Lasers: Proposal For Terahertz Laser Efficiency Improvements, Tillmann Kubis, Saumitra Raj Mehrotra, Gerhard Klimeck

Birck and NCN Publications

Conceptual disadvantages of typical resonant phonon terahertz quantum cascade lasers 􏰎THz-QCLs􏰍 are analyzed. Alternative designs and their combination within a concrete device proposal are discussed to improve the QCL performance. The improvements are 􏰎1􏰍 indirect pumping of the upper laser level, 􏰎2􏰍 diagonal optical transitions, 􏰎3􏰍 complete electron thermalization, and 􏰎4􏰍 materials with low effective electron masses. The nonequilibrium Green’s function method is applied to predict stationary electron transport and optical gain. The proposed THz-QCL shows a higher optical gain, a lower threshold current, and a higher operation temperature. Alloy disorder scattering can worsen the QCL performance.

Universality Of Non-Ohmic Shunt Leakage In Thin-Film Solar Cells, Sourabh Dongaonkar, J. D. Servaites, G. M. Ford, S. Loser, R. M. Gelfand, H. Mohseni, Hugh Hillhouse, R. Agrawal, M. A. Ratner, T. J. Marks, Mark S. Lundstrom, Muhammad A. Alam

Other Nanotechnology Publications

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In, Ga)Se-2 (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V < similar to 0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (I-sh), across all three solar cell types considered, is characterized by the following common phenomenological features: (a) voltage symmetry about V = 0, (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited (SCL) current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518509]

The Effects Of Electricity Pring On Phev Competitiveness, Shisheng Huang, Bri-Mathias S. Hodge, Farzad Taheripour, Joseph F. Pekny, Gintaras V. Reklaitis, Wallace E. Tyner

PPRI Digital Library

Plug-in Hybrid Electric Vehicles (PHEVs) will soon start to be introduced into the transportation sector, thereby raising a host of issues related to their use, adoption and effects on the electricity sector. Their introduction has the potential to significantly reduce carbon emissions from the transportation sector, which has led to government policies aimed at easing their introduction. If their wide-spread adoption is set as a target it is imperative to consider the effects of existing policies that may increase or decrease their adoption rate. In this study, we present a micro level electricity demand model that can gauge the effects …

Theory And Applications Of Compressive Sensing, Atul Divekar, Okan Ersoy

Department of Electrical and Computer Engineering Technical Reports

This thesis develops algorithms and applications for compressive sensing, a topic in signal processing that allows reconstruction of a signal from a limited number of linear combinations of the signal. New algorithms are described for common remote sensing problems including superresolution and fusion of images. The algorithms show superior results in comparison with conventional methods. We describe a method that uses compressive sensing to reduce the size of image databases used for content based image retrieval. The thesis also describes an improved estimator that enhances the performance of Matching Pursuit type algorithms, several variants of which have been developed for …

Network Science: Using Information Technology To Enable Collaboration, Arden L. Bement Jr.

PPRI Digital Library

No abstract provided.

Universality Of Non-Ohmic Shunt Leakage In Thin-Film Solar Cells, Sourabh Dongaonkar, Jonathan D. Servaites, Grayson M. Ford, Stephen Loser, James E. Moore, Ryan M. Gelfand, Hooman Mohseni, Hugh W. Hillhouse, Rakesh Agrawal, Mark A. Ratner, Tobin J. Marks, Mark Lundstrom, Muhammad A. Alam

Birck and NCN Publications

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In,Ga)Se₂ (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V< ∼ 0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (I_sh), across all three solar cell types considered, is characterized by the following common phenomenological features: (a) voltage symmetry about V = 0, (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from …

Uncertainty Propagation In A Multiscale Model Of Nanocrystalline Plasticity, Marisol Koslowski, Alejandro Strachan

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We characterize how uncertainties propagate across spatial and temporal scales in a physicsbased model of nanocrystalline plasticity of fcc metals. Our model combines molecular dynamics (MD) simulations to characterize atomic level processes that govern dislocation basedplastic deformation with a phase field approach to dislocation dynamics (PFDD) that describes how an ensemble of dislocations evolve and interact to determine the mechanical response of the material. We apply this approach to a nanocrystalline Ni specimen of interest in micro-electromechanical (MEMS) switches. Our approach enables us to quantify how internal stresses that result from the fabrication process affect the properties of dislocations (using …

Safety Enhancement Of The Indot Network Pavement Friction Testing Program: Macrotexture And Microtexture Testing Using Laser Sensors, Shuo Li, Samy Noureldin, Karen Zhu

JTRP Technical Reports

The Indiana Department of Transportation has conducted annual network inventory friction testing using the locked wheel trailer to reduce wet pavement crashes. However, issues have arisen concerning the data credibility and field operation safety on high-speed highway facilities. Some researchers have investigated the evaluation of pavement friction using macrotexture measurements and found the relationship between friction and macrotexture is extremely weak. Currently, macrotexture can be readily measured at highway speeds, but microtexture is evaluated using friction at low speeds from a surrogate device. Microtexture plays an important role in friction force. The evaluation of pavement friction from texture measurements will …

Site Verification Of Weigh-In-Motion Traffic And Tirtl Classification Data, Shuo Li, Yingzi (Eliza) Du, Yi Jiang

JTRP Technical Reports

Quality weigh-in-motion (WIM) traffic data is essential not only in general transportation application, but also in pavement design. The new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for New and Rehabilitated Pavement Structures requires information on the detailed truck traffic, such as truck traffic volume, truck traffic monthly and hourly variations, vehicle class distribution, axle load, and axle load distributions, instead of the traditional ESALs. In addition, the Indiana Department of Transportation (INDOT) needs to collect traffic data frequently so as to timely provide accurate traffic information for planning, program development, operations, and pavement management. Currently, INDOT is using the pneumatic …

Small-Scale Solutions To Grand Challenges In Thermal Management, Suresh V. Garimella

Birck and NCN Publications

Research needs in the field of thermal management of microelectronics and microsystems are identified, followed by a brief discussion of recent advances in solution approaches. These include novel solutions that rely on two-phase flow at the microscale, micropumps, droplet actuation on structured surfaces, passive transport in wick structures, ion-driven and piezoelectrically driven airflow, nanostructured thermal materials, and novel diagnostic tools.

Using Performance Measures To Improve Signal System Performance, Ross Haseman, Christopher Day, Darcy Bullock

Indiana Local Technical Assistance Program (LTAP) Technical Reports

Recent emphasis on improving signal system performance has prompted research on the collection of enhanced quantitative data for making operational decisions, the development of a systematic method for monitoring and recording system performance and the definition of quantitative performance measures to identify opportunities to improve corridor traffic operations. This document summarizes the highlights from several publications which document the motivation, theory and application of traffic signal performance measures. Topics discussed include the advantages of monitoring signal system performance without labor intensive field observations. The benefits of real time monitoring and evaluation of signal system performance as well as system troubleshooting. …

Long Term Hydrologic Impact Assessment – Model Builder Approach, Cibin Raj

GIS Day

Climate change has significant impact on hydrology and water quality. A simple Long Term Hydrologic Impact Assessment tool has been developed using model builder in ArcGIS 9.3 to simulate hydrology and water quality. The model developed to read precipitation data from netCDF format to simulate runoff. The tool box developed to simulate hydrology based on the widely used USDA Curve Number method and water quality using EMC (event mean concentration) of pollutant. The model in GIS allows easier management of input and output data and allows critical spatial and visual interpretation. The model developed for Wisconsin State, where the precipitation …

Endogenous Sirnas And Noncoding Rna-Derived Small Rnas Are Expressed In Adult Mouse Hippocampus And Are Up-Regulated In Olfactory Discrimination Training., Neil Smalheiser, G Lugli, Jyothi Thimmapuram, E.H. Cook, J Larson

Cyber Center Publications

We previously proposed that endogenous siRNAs may regulate synaptic plasticity and long-term gene expression in the mammalian brain. Here, a hippocampal-dependent task was employed in which adult mice were trained to execute a nose-poke in a port containing one of two simultaneously present odors in order to obtain a reward. Mice demonstrating olfactory discrimination training were compared to pseudo-training and nose-poke control groups; size-selected hippocampal RNA was subjected to Illumina deep sequencing. Sequences that aligned uniquely and exactly to the genome without uncertain nucleotide assignments, within exons or introns of MGI annotated genes, were examined further. The data confirm that …

A Laboratory Study Of Bendway Weirs As A Bank Erosion Countermeasure, Dennis A. Lyn, R. Cunningham

JTRP Technical Reports

Bendway weirs are being considered by INDOT as a potential alternative countermeasure for bank erosion at channel bends that might be more environmentally sensitive than the traditional riprap. These are linear structures extending riverwards from the bank to be protected, but unlike the more familiar spur structure, they are intended to be overtopped by the design flow. The flow over the weir crest is supposed to be directed perpendicular to the plane of the weir, and so by appropriate placement of the weir(s), the flow can be directed away from the bank, thus protecting it.

Design guidelines for such structures …

Experimental Evaluation And Implementation Of Post-Tensioning In Concrete Bridge Decks, Julio A. Ramirez, Gerardo Aguilar

JTRP Technical Reports

A research program was conducted to evaluate the design recommendations for transverse post-tensioning of bridge decks developed in the FHWA/IN/JTRP/2002-26 (SPR-2409) report. The test specimen consisted of a 40x18 ft cast-in-place concrete deck on precast pretensioned girders. Thirty-two tests were carried out by applying different distributions of transverse post-tensioning force, in combination with a changing number of diaphragms, and two conditions of end-restraint at the supports. The transverse post-tensioning stress ranged from 400 to 1 200 psi and the number of diaphragms was reduced from five to zero.

The main findings support the notion that the presence of diaphragms affects …

Portland Cement Concrete Pavement Permeability Performance, Javier Castro, Robert Spragg, Phil Kompare, W. Jason Weiss

JTRP Technical Reports

The objective of this project was to evaluate the transport properties of concrete pavement in the state of Indiana using common testing procedures. Specifically this work evaluated the absorption of water, the absorption of deicing solutions, and electrical conductivity. A series of concrete paving mixtures were tested to provide a range of values that were typical for the state of Indiana. While similar mixture proportions were used for the mixtures in Indiana differences in the magnitude of water absorbed occurred. A series of mortars were tested to illustrate the effect of curing conditions, water to cement ratio, and paste volume. …

Control And Repair Of Bridge Deck Cracking, Robert J. Frosch, Sergio Gutierrez, Jacob S. Hoffman

JTRP Technical Reports

Cracking of bridge decks poses a significant threat to the lifespan of our nation’s bridges. Cracking has been shown to occur in various climates and geographical areas and can be seen on various types of superstructures. Often these cracks appear before or shortly after opening the bridge to live loads. Cracks in the deck create a path for water and deicing salts to reach the steel, often leading to corrosion of the reinforcement, greatly reducing the durability of the deck. Measures must be taken during design and construction to control bridge deck cracking and prolong the lifespan of bridges. In …

The Indiana Local Technical Assistance Program Roller Compacted Concrete Pavement Manual For Local Government Agencies, Kyung Joon Shin, Neal Carboneau

Indiana Local Technical Assistance Program (LTAP) Technical Reports

Interest in the use of Roller Compacted Concrete (RCC) pavement (RCCP) for local roads and streets has increased. The Indiana Local Technical Assistance Program (LTAP), which is a part of the Purdue University School of Civil Engineering, has developed this document to assist local agencies with the implementation of roller compacted concrete as a paving material. This manual is intended for those interested in planning, designing and constructing RCCP for local roads and streets. It provides design guidelines, construction guidelines, local case studies, guide specifications and paving plan guidelines.

Green Technology: Think Globally, Act Locally, Arden L. Bement Jr.

PPRI Digital Library

No abstract provided.

Forecasting Of Highway Revenues Under Various Options, Bismark R.D.K. Agbelie, Qiang Bai, Samuel Labi, Kumares C. Sinha

JTRP Technical Reports

Throughout the United States, state highway revenue, which is dominated by receipts from fuel taxes, has failed to keep up with expected investments required for infrastructure preservation and improvement. The reasons for this trend include the increasing fuel efficiency of vehicles, slowing of the growth in vehicle-miles of travel, and the erosion of the purchasing power of the dollar due to inflation. This development motivates highway agencies not only to seek revisions of existing funding structures but also to consider potential alternative sources.

To establish and implement an effective and efficient financing strategy that incorporates potential new funding sources, it …

Long Term Performance Of A Porous Friction Course, Rebecca S. Mcdaniel, Karol J. Kowalski, Ayesha Shah, Jan Olek, Robert J. Bernhard

JTRP Technical Reports

In 2003, the Indiana Department of Transportation and the Federal Highway Administration allowed a test section of Porous Friction Course (PFC) to be placed on I74 east of Indianapolis. The design, construction and early performance of that surface were compared to an adjacent SMA surface and a conventional Superpave HMA surface in a report prepared for the Institute for Safe, Quiet and Durable Highways (1). The early performance indicated that the PFC offered several advantages over the SMA and the conventional surfaces, including reduced tire/pavement noise, high friction and surface texture, and reduced splash and spray. There was …

Quantifying Benefits Of Traffic Signal Retiming, Christopher M. Day, Thomas M. Brennan Jr., Hiromel Premachandra, Alexander M. Hainen, Stephen M. Remias, James R. Sturdevant, Greg Richards, Jason S. Wasson, Darcy M. Bullock

JTRP Technical Reports

Improvements in the quality of service on a signalized intersection or arterial can be interpreted as a reduction in the user cost of service, which is expected to induce demand based on economic theory. This report presents a methodology for measuring and interpreting changes to user costs, and determining whether demand was induced. High-resolution signal event data and Bluetooth device MAC address matching are demonstrated in three case studies with the purpose of quantifying the impacts of changes in signal timing plans. In the first case study, 21 months of vehicle volume data are used to test whether demand was …

Determining Of The Binder Content Of Hot Mix Asphalt Containing Dolomitic Aggregates Using The Ignition Oven, Karol K. Kowalski, Rebecca S. Mcdaniel, Jan Olek, Ayesha Shah

JTRP Technical Reports

The binder content of an HMA mix is one of the critical factors affecting the quality of the mix. The ignition oven is one widely used method for determining the binder content, however, its use is problematic with some types of aggregates, including dolomites. With these aggregates, the mass loss continues after the binder is burned off as the aggregates decompose and the test does not terminate at a stable mass. This study investigated the factors that affect this mass loss in problematic aggregates and developed a modified ignition oven procedure to limit this mass loss. The mass loss in …

Identification Of Laboratory Technique To Optimize Superpave Hma Surface Friction Characteristics, Karol J. Kowalski, Rebecca S. Mcdaniel, Jan Olek

JTRP Technical Reports

Wet pavement friction is known to be one of the most important roadway safety parameters. In this research, frictional properties of flexible (asphalt) pavements were investigated.

As a part of this study, a laboratory device to polish asphalt specimens was refined and a procedure to evaluate mixture frictional properties was proposed. Following this procedure, 46 different Superpave mixtures, one stone matrix asphalt (SMA) mixture and one porous friction course (PFC) mixture were tested. In addition, 23 different asphalt and two concrete field sections were also tested for friction and noise.

The results of both field and laboratory measurements were used …

Development Of Internally Cured Concrete For Increased Service Life, John Schlitter, Ryan Henkensiefken, Javier Castro, Kambiz Raoufi, Jason Weiss, Tommy Nantung

JTRP Technical Reports

Higher strength, lower water to cement ratio (w/c) concrete has been advocated over the last two decades due to its increased strength and reduced permeability. The lower w/c of these concretes makes them susceptible to autogenous shrinkage. This autogenous shrinkage can be significant and can be a contributing factor to early age cracking. Internal curing was investigated as a potential method to improve the durability of concrete pavements and bridge decks. Prewetted lightweight aggregate was used to supply water to the hydrating cement paste. This additional water can counteract the hindered strength development, suspended hydration, autogenous shrinkage, and early age …