Engineering Commons^™

Connecting Science With Engineering: Using Inquiry And Design In A Teacher Professional Development Course, Louis S. Nadelson, Patricia Pyke, Janet Callahan, Anne Hay, Joshua Pfiester, Mark A. Emmet

Curriculum, Instruction, and Foundational Studies Faculty Publications and Presentations

The engineering design process has evolved over time to be the central and effective framework that engineers use to conduct their work. Logically, K-12 STEM professional development efforts have then attempted to incorporate the design process into their work. There has been little in the STEM literature, though, of the explicit measurement of the growth in design process knowledge. Our study presents findings of significant improvements in knowledge of the design process that resulted over the course of a recent summer STEM institute and professional development program among K-5 teachers.

As more emphasis is placed on integrating STEM into the …

An Industry-University Partnership Case Study, Peter Schuster

Mechanical Engineering

At many universities, senior undergraduate mechanical engineers work in teams on industry-sponsored capstone design projects. These projects provide an excellent opportunity for students to synthesize their courses, work with the more realistic deadlines and expectations of industry, and interact with company representatives. It also give industrial partners a chance to become educational partners with the university, preview potential new hires, and complete some noncritical projects at low cost.

This paper presents a case study of a successful six-year partnership between the Automotive Bumper Project committee of the American Iron & Steel Institute (AISI) and a mechanical engineering department. The AISI …

Developing And Assessing Stem Curriculum With The Intent Of Promoting Technological Literacy, Scott Bartholomew, Geoff Wright, Ron Terry

Faculty Publications

Developing and Assessing STEM Curriculum with the Intent of Promoting Technological Literacy Technological literacy is a key component of President Barack Obama’s $260 Million STEM educational initiative (Office of the Press Secretary, 2009). Central to his plan is STEM teacher training and curriculum development. Both of these issues were addressed and are currently being measured by the research outlined in this paper. Spring2010 a collection of technology and engineering education graduate students developed with mentoring from two technology and engineering education professors 20 lesson unit and lesson plans promoting technological literacy. The lesson plans are currently being used and assessed …

Localization Of Objects Using Stochastic Tunneling, Mohammed Rana Basheer, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a novel wireless localization scheme in the three-dimensional domain that employs stochastic optimization with tunneling transformation to recursively estimate the location of wireless tags in a network from pair wise signal strength measurements. Spatially co-located wireless tags, receiving signals from a common transmitter, exhibit correlation in their Received Signal Strength Indicator (RSSI) values. Hence in a network of wireless tags, with pair wise correlation coefficients available, posterior distribution of the unknown tag separation is used to relatively localize them using maximum a posteriori (MAP) Estimator. However, due to the non-convex/non-tractable nature of this posterior distribution, deterministic optimization …

Multi-Hop Framework For Battery-Less Devices Using Passive Rf Communication, Vikram Reddy Surendra, Maciej Jan Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

Typical wireless multi-hop networks employ active communication where RF signal is actively generated by a sending node. in contrast, backscatter communication modulates backscattered RF signal that requires significantly less energy to operate than the active one. This paper proposes a novel, multi-hop architecture for such backscatter-Based communication that is not currently present in the literature. Such a system consists of a powerful reader and small, battery-less nodes. the reader generates the original RF signal, while the passive devices backscatter this signal to communicate among themselves thus enabling multihop transmission from far-away nodes. the paper presents the generic analysis of the …

Spectrum Management For Wireless Networks Using Adaptive Control And Game Theory, Swagoto Roy, Liuju Wu, Macie Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

Radio frequency spectrum in wireless communication is a common resource shared by all collocated devices. Most spectrum management schemes rely on a centralized base station-receiver station relaying architecture. in contrast, infrastructure-less systems including wireless ad hoc networks require a scalable, distributed methodology. Moreover, the access has to be coordinated among the nodes in the network in the aspects which include power and rate adaptation. the challenge is to find an optimal tradeoff between such parameters not only for a particular link but also for an entire multi-hop network. Several existing schemes address power, throughput and Signal-to-Interference ratio (SIR) control on …

Soft-Decision Feedback Turbo Equalization For Multiple Antenna Systems With Multilevel Modulations, Amirhossein Rafati, Huang Lou, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Many communication systems today encounter the problem of data transmission over a channel with inter-symbol interference (ISI). the purpose of this paper is to develop a low-complexity, iterative soft-decision feedback equalization (SDFE) receiver for severe, frequency selective ISI channels. the proposed SDFE algorithm offers a novel approach to combat error propagation. in addition, its computational complexity grows only linearly with the number of equalizer coefficients, compared to the quadratic complexity of minimum mean square error-Based linear turbo equalizer with time-varying coefficients. Performance of the proposed detection scheme is verified through simulations using different signal constellations. Simulation results show that our …

E-10a Mc2a Systems Engineering Case Study, Air Force Center For Systems Engineering, William Albery

AFIT Documents

No abstract provided.

Developing A Regional Land Use Drought Index In Florida, Chi-Han Cheng, Fidelia Nnadi

2011 Symposium on Data-Driven Approaches to Droughts

Drought is a natural phenomenon that occurs when a significant decrease of water availability during a significant period of time and over a larger area. Drought indices can be a useful tool to assess and respond to drought. However, current drought indices could not fully show the land use effects and they have limitation in data sources. ENSO influence the climate of Florida; where El Niño years tend to be cooler and wetter, and La Niña years tend to be warmer and drier than normal in the fall through the spring, with the strongest effect in the winter. Both prolonged …

Review Of Gasoline, Diesel, And Ethanol Biofuels From Grasses And Plants, By Ram B. Gupta And Ayhan Demirbas., Adam J. Liska

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A new book on the production of biofuels by Gupta and Demirbas provides technical insight into the conversion processes that could provide a range of domestic fuels from plant materials to substitute for foreign oil. It focuses primarily on conversion processes for production of cellulosic ethanol, Fischer-Tropsch diesel, pyrolysis bio-oil, and hydrothermal biocrude from biomass resources, as well as "first-generation" grain ethanol and biodiesel from vegetable oil. In addition to a detailed summary of these chemical processes, the book provides a briefer treatment of related matters such as biofuel policy, economics, and environmental issues.

Reconfigurable Sampling For Enhanced Energy Efficiency In Power-Constrained Wireless Systems, Timothy Kurp

Master's Theses

Advancement in microelectronics and wireless communications has nurtured the development of low power and low cost wireless systems such as sensor networks. Each node is typically driven by a battery, which has a limited energy capacity that directly constrains node, and network lifetime. This presents a bottleneck for the widespread exploitation of wireless sensing technology. Therefore, improving the energy efficiency of wireless sensing devices is of critical importance and has attracted the attention of the research community.

In this work, a data-driven method has been proposed and systematically investigated. Specifically, this technique reconfigures, in real time, the rate of data …

Probabilistic Assessment Of Drought Characteristics Using A Hidden Markov Model, Ganeshchandra Mallya, Shivam Tripathi, Sergey Kirshner, Rao S. Govindaraju

2011 Symposium on Data-Driven Approaches to Droughts

Droughts are evaluated using drought indices that measure the departure of meteorological and hydrological variables such as precipitation and stream flow from their long-term averages. While there are many drought indices proposed in the literature, most of them use pre-defined thresholds for identifying drought classes ignoring the inherent uncertainties in characterizing droughts. In this study, a hidden Markov model (HMM) [1] is developed for probabilistic classification of drought states. The HMM captures space and time dependence in the data. The proposed model is applied to assess drought characteristics in Indiana using monthly precipitation and stream flow data. The comparison of …

Drought Regionalization Of Brazos River Basin Using An Entropy Approach, Deepthi Rajsekhar, Ashok Mishra, Vijay P. Singh

2011 Symposium on Data-Driven Approaches to Droughts

Assessment and understanding of past climate is an important step for drought mitigation and water resources planning. In this study, stream flows imulation obtained from the variable infiltration capacity(VIC) model was used for drought characterization, and subsequently regionalization was done based on the annual severity level, for the Brazos basin in Texas over a time span of 1949-2000. It is important to study drought characteristics with in a regional context. Hence, identification of homogenous drought regions is a prerequisite, so that the drought characteristics can be studied with in each of these regions. In this study, the concept of entropy …

A Look At 20th Century Droughts, Vijay P. Singh, Ashok K. Mishra

2011 Symposium on Data-Driven Approaches to Droughts

Droughts exercise a profound effect on the social and economic fabric of nations. Many nations of the world experienced droughts encompassing the full spectrum of severity, areal extent and duration. The result has been that the economic development was hampered and many countries have not yet recouped fully from the ravages of droughts. The first decade of the 21st century has also witnessed varying degrees of droughts across the globe. Therefore, we ask the following questions: (a) Do droughts affect every part of the world? (b) Are there similarities in major droughts around the world? (c) Are climate change and …

On The Physics Of Droughts, M. Levent Kavvas

2011 Symposium on Data-Driven Approaches to Droughts

By means of a simple general circulation model of the northern hemisphere the interaction of atmospheric and hydrologic processes during droughts will be analyzed at continental scale. It will be shown by numerical solutions of this model that the mechanism leading to droughts is a non-linear positive feedback mechanism in the sense that it feeds on itself. Imposing a temperature wave over western USA for a short period on the order of few months induces geophysical conditions in that region which tend to reduce the hydrologic water storage for a period on the order of years. The mechanisms for returning …

Scattering Mechanisms In A High-Mobility Low-Density Carbon-Doped (100) Gaas Two-Dimensional Hole System, J. D. Watson, S. Mondal, G. A. Csathy, M. J. Manfra, E. H. Hwang, S. Das Sarma, L. N. Pfeiffer, K. W. West

Birck and NCN Publications

We report on a systematic study of the density dependence of mobility in a low-density carbon-doped (100) GaAs two-dimensional hole system (2DHS). At T = 50 mK, a mobility of 2.6 x 10(6) cm(2)/Vs at a density p = 6.2 x 10(10)cm(-2) was measured. This is the highest mobility reported for a 2DHS to date. Using a backgated sample geometry, the density dependence of mobility was studied from 2.8 x 10(10) cm(-2) to 1 x 10(11) cm(-2). The mobility vs density cannot be fit to a power law dependence of the form alpha similar to p(alpha) using a single exponent …

Supersymmetry Identifies Molecular Stark States Whose Eigenproperties Can Be Obtained Analytically, Mikhail Lemeshko, Mustafa Mustafa, Sabre Kais, Bretislav Friedrich

Birck and NCN Publications

We made use of supersymmetric (SUSY) quantum mechanics to find the condition under which the Stark effect problem for a polar and polarizable closed-shell diatomic molecule subjected to collinear electrostatic and nonresonant radiative fields becomes exactly solvable. The condition Delta omega = omega(2)/4(m+1)(2) connects values of the dimensionless parameters omega and Delta omega that characterize the strengths of the permanent and induced dipole interactions of the molecule with the respective fields. The exact solutions are obtained for the vertical bar(J) over tilde = m, m; omega, Delta omega > family of 'stretched' states. The field-free and strong-field limits of the combined-fields …

Surgical Cutting And Ablation By Energy Based Devices: Principles And Applications, Garrett Mcguinness, Joseph A. Mcgeough, Graham Gavin, Brendan O'Daly

Conference Papers

Advances in ultrasound, radiofrequency, and water jet systems are facilitating their increased use in new medical ablation or cutting applications in fields as diverse as cardiology, orthopaedics, ophthalmology, dermatology, oncology and neurosurgery. These methods involve controlled alteration or destruction of tissues via the application of thermal, electrical or kinetic energy. This market segment is characterised by advanced devices capable of heating or cooling tissue from -200°C to 400°C, or inducing vibrations of up to 60 kHz to cause tissue damage. The medical conditions targeted primarily pertain to chronic and age-related diseases, but elective and cosmetic procedures are also addressed. Medical …

An Evaluation Of Constitutive Laws And Their Ability To Predict Flow Stress Over Large Variations In Temperature, Strain, And Strain Rate Characteristic Of Friction Stir Welding, Katherine Lynn Kuykendall

Theses and Dissertations

Constitutive laws commonly used to model friction stir welding have been evaluated, both qualitatively and quantitatively, and a new application of a constitutive law which can be extended to materials commonly used in FSW is presented. Existing constitutive laws have been classified as path-dependent or path-independent. Path-independent laws have been further classified according to the physical phenomena they capture: strain hardening, strain rate hardening, and/or thermal softening. Path-dependent laws can track gradients in temperature and strain rate characteristic to friction stir welding; however, path-independent laws cannot. None of the path-independent constitutive laws evaluated has been validated over the full range …

The Effect Of Adding Organic Polymers To Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. Coughlan, N. M. Cummins, A. W. Wren, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

To conclude, the addition of polymers to GPCs resulted in little change to the Tw and Ts, however the compressive strength was found to decrease slightly. ASAP tests revealed that the cements may undergo some structural changes as a result of these additions. In the future perhaps the addition of organic polymers suspended in the liquid phase as part of the cement may yield improved results in this type of study. © 2011 IEEE.

Aluminium-Free Glass Polyalkenoate Spinal Cements, A. W. Wren, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Addition of Yitanium increased the Wt & St and the sf strength of these cements compared to the control (BT 101). © 2011 IEEE.

An Argument For The Importance Of Material Property Characterization Of Hydrogels, J. M. Zuidema, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrogels are being fabricated for use in many tissue engineering applications. In order to advance the field, material properties must be characterized to determine the most desirable attributes. The data presented shows the importance of both surface charge and mechanical properties on dorsal root ganglia neurite extension. © 2011 IEEE.

Using Cerebrospinal Fluid For In Situ Fabrication Of Injectable Alginate Hydrogels For Spinal Cord Repair, C. A. Mckay, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Severe mechanical trauma of the spinal cord induces a secondary injury response that contributes to post injury cell death and the formation of barriers inhibitory to neuronal regeneration. It is believed that engineered scaffolds produce favorable results when they mimic the properties of the t issue that they are aiming to replicate. Alginate hydrogels have been shown to be beneficial in a number of biomaterial applications and this study shows that alginate hydrogels formed in the presence of an artificial cerebrospinal fluid are able to form hydrogels with mechanical properties similar to those exhibited by neural tissue in the CNS. …

Aligned, Electrospun Topography For Use With External Stimulus Systems, S. G. Quallich, C. J. Rivet, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Variations in fiber density, diameter, and orientation can be used to direct cell migration and guide neurite growth. The characterization of electro spun fibers is essential prior to conducting further research that utilizes electro spun scaffolds to control the magnitude and direction of cell migration and neurite growth. The goal of this study is to create highly aligned, electro spun fibers on poly-L-lactic acid (PLLA) films in parallel and perpendicular orientations to the long axis of rectangular cover slips. Fibers were electro spun into scaffolds and scanning electron microscopy (SEM) was used to characterize fiber density and orientation. The construction …

Photogrammetric Measurement Of Recession Rates Of Low Temperature Ablators Subjected To High Speed Flow, David W. Callaway

Theses and Dissertations

This research advances a technique to simulate high temperature/high speed effects in a high speed/low temperature environment and to capture recession of the test article in three-dimensions. A method of fabricating dry ice test articles was developed, and the AFIT Mach 3 pressure-vacuum wind tunnel was used in combination with the dry ice test articles to collect three-dimensional ablation data for models of different shapes at stagnation pressures ranging from approximately 0.4 atm to 3 atm and stagnation temperatures equivalent to room temperature. High speed Schlieren photography was used for visualization, and the three dimensional shape change was quantified with …

Simulations For The Test Flight Of An Experimental Hale Aircraft, Brooke E. Kaszynski

Theses and Dissertations

Recent events, such as the crash of NASA's Helios aircraft during a test flight, show that more must be known about the nonlinear control of HALE aircraft. Shearer, Cesnik and their co-workers have developed a code that is a practical solution to the coupled nonlinear aeroelasticity and flight dynamics of very flexible aircraft called the University of Michigan's Nonlinear Aeroelastic Simulation Toolbox (UM/NAST). They are also in the process of developing a model HALE aircraft called X-HALE which will be used to validate this code experimentally. This research performs flight simulations with UM/NAST so as to make predictions about X-HALE's …

Study Of Varying Boundary Layer Height On Turret Flow Structures, Renato Jelic

Theses and Dissertations

The Air Force Institute of Technology and the Air Force Research Labs are investigating flows over turrets which are commonly encountered in directed energy integrations with air vehicles. In this work, the computational study was performed using the NASA developed time-marching finite volume code OVERFLOW 2.2 to analyze the effect of boundary layer height on symmetrical and non-symmetrical turret geometries. The effects of aerodynamics yield to the aberration of the laser beam through two methods, aero-optical and aero-mechanical jitter. The analysis of the flow features, pressure fluctuations, density fluctuations, and forces and moments on the various geometries was conducted to …

Host-Based Systemic Network Obfuscation System For Windows, Kevin E. Huber

Theses and Dissertations

Network traffic identifies the operating system and services of the host that created the traffic. Current obfuscation programs focus solely on the Transport and Internet layer protocols of the TCP/IP model. Few obfuscation programs were developed to run on a Windows operating system to provide host-based obfuscation. Systemic Network Obfuscation System (SNOS) was developed to provide a thorough obfuscation process for network traffic on the Windows operating system. SNOS modifies the protocols found at all layers of the TCP/IP model to effectively obfuscate the Windows operating system and services running on the host.

Coverage Of Continuous Regions In Euclidean Space Using Homogeneous Resources With Application To The Allocation Of The Phased Array Radar Systems, Kassandra M. Merritt

Theses and Dissertations

Air surveillance of United States territory is an essential Department of Defense function. In the event of an incoming aerial attack on North America, the DoD, Department of Homeland Security, and Federal Aviation Administration surveillance capabilities are critical to discovering and tracking the threat so that it can be eliminated. Many of the currently used surveillance radar will reach the end of their design life within ten to twenty years. By replacing the current radar network with a single integrated network of Multifunction Phased Array Radar (MPAR) units, surveillance capabilities can be enhanced and life cycle cost can be reduced. …

Fabrication And Analysis Of Variable Density Poly-(L)-Lactic Acid Fiber Scaffolds, N. W. Zaccor, C. J. Rivet, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Poly-L-lactic acid (PLLA) is an extensively studied synthetic polymer that has demonstrated utility as a scaffolding material. A common technique for the fabrication of PLLA scaffolds is electrospinning. The purpose of the present material study was to assess whether an electrospinning process could produce consistent and uniform PLLA scaffold densities. An 8% PLLA solution was made using a 1:1 chloroform: dichloromethane solution and was then run through an electrospinning apparatus. Samples were spun onto 4% PLLA films for 2- or 20-min. Scanning electron microscopy (SEM) was used for imaging the scaffolds. A nine-measurement data set was used for the assessment …