Engineering Commons^™

Quantum And Classical Magnetoresistance In Ambipolar Topological Insulator Transistors With Gate-Tunable Bulk And Surface Conduction, Jifa Tian, Cuizu Chang, Helin Cao, Ke He, Xucun Ma, Qikun Xue, Yong P. Chen

Birck and NCN Publications

Weak antilocalization (WAL) and linear magnetoresistance (LMR) are two most commonly observed magnetoresistance (MR) phenomena in topological insulators (TIs) and often attributed to the Dirac topological surface states (TSS). However, ambiguities exist because these phenomena could also come from bulk states (often carrying significant conduction in many TIs) and are observable even in non-TI materials. Here, we demonstrate back-gated ambipolar TI field-effect transistors in (Bi0.04Sb0.96)(2)Te-3 thin films grown by molecular beam epitaxy on SrTiO3(111), exhibiting a large carrier density tunability (by nearly 2 orders of magnitude) and a metal-insulator transition in the bulk (allowing switching off the bulk conduction). Tuning …

In-Situ Tem Observation Of The Response Of Ultrafine- And Nanocrystalline-Grained Tungsten To Extreme Irradiation Environments, Osman El-Atwani, J. A. Hinks, G. Greaves, Sean Gonderman, T. Qiu, M. Efe, Jean P. Allain

Birck and NCN Publications

The accumulation of defects, and in particular He bubbles, can have significant implications for the performance of materials exposed to the plasma in magnetic-confinement nuclear fusion reactors. Some of the most promising candidates for deployment into such environments are nanocrystalline materials as the engineering of grain boundary density offers the possibility of tailoring their radiation resistance properties. In order to investigate the microstructural evolution of ultrafine- and nanocrystalline-grained tungsten under conditions similar to those in a reactor, a transmission electron microscopy study with in situ 2 keV He+ ion irradiation at 950 degrees C has been completed. A dynamic and …

Full Control Of Quadruple Quantum Dot Circuit Charge States In The Single Electron Regime, M. R. Delbecq, T. Nakajima, T. Otsuka, S. Amaha, J. D. Watson, Michael J. Manfra, S. Tarucha

Birck and NCN Publications

We report the realization of an array of four tunnel coupled quantum dots in the single electron regime, which is the first required step toward a scalable solid state spin qubit architecture. We achieve an efficient tunability of the system but also find out that the conditions to realize spin blockade readout are not as straightforwardly obtained as for double and triple quantum dot circuits. We use a simple capacitive model of the series quadruple quantum dots circuit to investigate its complex charge state diagrams and are able to find the most suitable configurations for future Pauli spin blockade measurements. …

Long-Term Behavior Of Hygrothermaly Conditioned Concrete-Filled Fiber-Reinforced Polymeric Tubes Subjected To Axial Load, Sergio Arambula, Felipe Acosta

Purdue Road School

No abstract provided.

Effect Of Cellular Phone And Radar Forensics On Search And Rescue Duration For General Aviation Aircraft Accidents In The Contiguous United States, Ryan J. Wallace

Journal of Aviation Technology and Engineering

Emergency Locator Transmitters (ELT) are generally the primary tool for locating distressed aircrews following an aircraft accident. In 2009, the International COSPAS-SARSAT organization ordered the cessation of 121.5 MHz ELT satellite monitoring to alleviate systemic false alarms and encourage pilots to upgrade ELTs to modern 406 MHz models. While most nations acquiesced to the mandate, the United States encountered severe resistance from pilot groups. As a result, 121.5 MHz ELTs are still in use in the U.S. but remain unmonitored by satellite systems. This study sought to assess the impact of alternative search methods such as radar and cellular phone …

Examining Young Students’ Problem Scoping In Engineering Design, Jessica Watkins, Kathleen Spencer, David Hammer

Journal of Pre-College Engineering Education Research (J-PEER)

Problem scoping—determining the nature and boundaries of a problem—is an essential aspect of the engineering design process. Some studies from engineering education suggest that beginning students tend to skip problem scoping or oversimplify a problem. However, the ways these studies often characterize students’ problem scoping often do not reflect the complexity found in experts’ designing and rely on the number of criteria a student mentions or the time spent problem scoping. In this paper, we argue for methodological approaches that take into account not just what students name as criteria, but also how they weigh, balance, and choose between criteria …

High School Student Information Access And Engineering Design Performance, Nathan Mentzer

Journal of Pre-College Engineering Education Research (J-PEER)

Developing solutions to engineering design problems requires access to information. Research has shown that appropriately accessing and using information in the design process improves solution quality. This quasi-experimental study provides two groups of high school students with a design problem in a three hour design experience. One group has access to the internet while the other does not. Quality of design solution was measured and the two groups were compared. Solution quality did not change significantly. Student information requests were categorized and the most commonly requested piece of information related to cost of materials. Students spent substantially more time in …

Shoot For The Moon! The Mentors And The Middle Schoolers Explore The Intersection Of Design Thinking And Stem, Maureen P. Carroll Ph.D.

Journal of Pre-College Engineering Education Research (J-PEER)

This paper describes the journey of a group of university students as they worked with underserved middle school students as mentors in a STEM-based afterschool program. Design thinking provided a frame within which students learned how to be mentors, how to create user-centered learning experiences, and how to share their experiences as developing STEM professionals with middle school students.

A Framework For Quality K-12 Engineering Education: Research And Development, Tamara J. Moore, Aran W. Glancy, Kristina M. Tank, Jennifer A. Kersten, Karl A. Smith, Micah S. Stohlmann

Journal of Pre-College Engineering Education Research (J-PEER)

Recent U.S. national documents have laid the foundation for highlighting the connection between science, technology, engineering and mathematics at the K-12 level. However, there is not a clear definition or a well-established tradition of what constitutes a quality engineering education at the K-12 level. The purpose of the current work has been the development of a framework for describing what constitutes a quality K-12 engineering education. The framework presented in this paper is the result of a research project focused on understanding and identifying the ways in which teachers and schools implement engineering and engineering design in their classrooms. The …

Electron Spin Magnetism Of Zigzag Graphene Nanoribbon Edge States, Kun Xu, Peide D. Ye

Birck and NCN Publications

The electron spin states of zigzag graphene nanoribbon (ZGNR) edge play a pivotal role in the applications of graphene nanoribbons. However, the exact arrangements of the electron spins remain unclear to date. In this report, the electronic spin states of the ZGNR edge have been elucidated through a combination of quantum chemical investigation and previous electron spin resonance experiment observations. An alternating alpha and beta spin configuration of the unpaired electrons along the ZGNR edge is established in ambient condition without any external magnetic field, and the origin of the spin magnetism of the ZGNR edge is revealed. It paves …

A Junction Tree Based Reinforcement Learning Algorithm For Coordinated Multi Agent Systems To Solve Network Level Signal Control Problems, Feng Zhu, Husain M. Abdul Aziz, Zinwu Qian, Satish Ukkusuri

Purdue Road School

No abstract provided.

A Meta-Heuristic Approach To Reposition Bicycles In A Public Bicycle Sharing System, Binh Luong, Pulkit Parikh, Satish Ukkusuri

Purdue Road School

No abstract provided.

Concrete Conductivity: Effects Of Temperature, Saturation And Air Content, Parth Panchmatia, Jan Olek, Nancy Whiting, Mike Byers, Tommy Nantung

Purdue Road School

No abstract provided.

Examining The Impact Of Pavement Rehabilitation Trigger Values And Annual Rehabilitation Funding On The Long-Term Network-Level Pavement Condition: A Case Study With The Indiana State Urban Road Network, Menna Noureldin, Jon D. Fricker, Kumares C. Sinha

Purdue Road School

Management of highway assets, including pavements, is immensely challenging in an era of uncertain funding for transportation agencies and higher service expectations from the public. Furthermore, the maintenance of pavement assets in good serviceable condition is one of the most cost-intensive operations for a highway agency.

Between 1996 and 2008, the Indiana DOT spending on improvement of pavement assets fluctuated between 35% and 50% of its asset management budget annually (Everett2012). Therefore, pavement managers are constantly exploring strategies to fulfill their mission of maintaining roads in good condition with the minimumbudget. Strategies may include examining the effectiveness of individual pavement …

Winter Storm Interstate Travel Times (January 5, 2014 Storm), Michelle Mekker, Darcy M. Bullock

Purdue Road School

No abstract provided.

Mobile Tools For Ltap Centers, Indiana Ltap

Purdue Road School

No abstract provided.

I-65/I-70 South Split Pavement Reconstruction: Documentation & Quantitative Analysis Using Time Lapse Photography, Steven Lavrenz, Teresa Morris, Darcy M. Bullock

Purdue Road School

No abstract provided.

Graphical Performance Measures For Practitioners To Triage Split Failure Trouble Calls, Richard S. Freije, Alexander M. Hainen, Amanda L. Stevens, Howell Li, W Benjamin Smith, Hayley Summers, Christopher M. Day, James R. Sturdevant, Darcy M. Bullock

Purdue Road School

Detector occupancy is commonly used to measure traffic signal performance. Despite improvements in controller computational power, there have been relatively few innovations in occupancy-based performance measures or integration with other data. This paper introduces and demonstrates the use of graphical performance measures based on detector occupancy ratios to verify potential split failures and other signal timing shortcomings reported to practitioners by the public. The proposed performance measures combine detector occupancy during the green phase, detector occupancy during the first five seconds of the red phase, and phase termination cause (gap out or force off). These are summarized by time of …

"Elemental Decomposition And Multi-Criteria Method For Valuing Transportation Infrastructure Elemental Decomposition And Multi-Criteria Method For Valuing Transportation Infrastructure ", Michelle S. Dojutrek, Samuel Labi

Purdue Road School

No abstract provided.

Observation Of Coulomb Repulsion Between Cu Intercalants In Cuxbi2se3, Chris Mann, Damien West, Ireneusz Miotkowski, Yong P. Chen, Shengbai Zhang, Chih-Kang Shih

Birck and NCN Publications

Using scanning tunneling microscopy and ab initio simulations, we have identified several configurations for Cu dopants in CuxBi2Se3, with Cu intercalants being the most abundant. Through statistical analysis, we show strong short-range repulsive interactions between Cu intercalants. At intermediate range (>5 nm), the pair distribution function shows oscillatory structure along the < 10 (1) over bar > directions, which appear to be influenced by different diffusion barriers along the < 10 (1) over bar > and < 2 (1) over bar(1) over bar > directions.

Effect Of Ionic Crosslinking On The Swelling And Mechanical Response Of Model Superabsorbent Polymer Hydrogels For Internally Cured Concrete, Qian Zhu, Christopher W. Barney, Kendra Erk

School of Materials Engineering Faculty Publications

The chemical and physical structure-property relationships of model superabsorbent polymer (SAP) hydrogels were characterized with respect to swelling behavior and mechanical properties in different ionic solutions (Na+, Ca2+, and Al3+). The model hydrogels were composed of poly(sodium acrylate-acrylamide) (PANa-PAM) copolymer with varying concentrations of PANa (0, 17, 33, 67, and 83 wt.%) and covalent crosslinking densities of 1, 1.5, and 2 wt.%. By synthesizing the hydrogels in-house, systems with independently tunable amounts of covalent crosslinking and anionic functional groups were created, allowing for the relative effects of covalent and ionic crosslinking on the properties of the hydrogels to be directly …

Droplet Evaporation On Heated Hydrophobic And Superhydrophobic Surfaces, Susmita Dash, Suresh V. Garimella

Birck and NCN Publications

The evaporation characteristics of sessile water droplets on smooth hydrophobic and structured superhydrophobic heated surfaces are experimentally investigated. Droplets placed on the hierarchical superhydrophobic surface subtend a very high contact angle (similar to 160 degrees) and demonstrate low roll-off angle (similar to 1 degrees), while the hydrophobic substrate supports corresponding values of 120 degrees and similar to 10 degrees. The substrates are heated to different constant temperatures in the range of 40-60 degrees C, which causes the droplet to evaporate much faster than in the case of natural evaporation without heating. The geometric parameters of the droplet, such as contact …

Variable-Cell Method For Stress-Controlled Jamming Of Athermal, Frictionless Grains, Kyle C. Smith, Ishan Srivastava, Timothy Fisher, Meheboob Alam

Birck and NCN Publications

A method is introduced to simulate jamming of polyhedral grains under controlled stress that incorporates global degrees of freedom through the metric tensor of a periodic cell containing grains. Jamming under hydrostatic (isotropic) stress and athermal conditions leads to a precise definition of the ideal jamming point at zero shear stress. The structures of tetrahedra jammed hydrostatically exhibit less translational order and lower jamming-point density than previously described maximally random jammed hard tetrahedra. Under the same conditions, cubes jam with negligible nematic order. Grains with octahedral symmetry having s > 0.5 (where s interpolates from octahedra [s = 0] to cubes …

Autonomous Indoor Localization For Fire Safety And Resource Location Via Field Mapping Techniques, Jaeyoung Kim, Kartik Ariyur, Yan Cui, Benjamin D. Branch, Joshua Ebung Umo

Libraries Faculty and Staff Presentations

An overall result of this collaboration between the Mechanical Engineering Dept. and the Purdue University Libraries (PUL) should result in building a big data framework that make have knowledge transfer for similar large scale geospatial data implementations. Such may promote best practices of data management where the library skill sets may aid faculty research and student learning. Here, the PUL is concerned with advancing the Mechanical Engineering‘s STEM pipeline capacity with this type of research, collaboration and data management engagement.

Autonomous Indoor Localization For Fire Safety And Resource Location Via Field Mapping Techniques (Android Version), Joshua Ebung Umo, Yan Cui, Kartik Ariyur, Benjamin D. Branch, Jaeyoung Kim

Libraries Faculty and Staff Presentations

An overall result of this collaboration between the Mechanical Engineering Dept. and the Purdue University Libraries (PUL) should result in building a big data framework that make have knowledge transfer for similar large scale geospatial data implementations. Such may promote best practices of data management where the library skill sets may aid faculty research and student learning. Here, the PUL is concerned with advancing the Mechanical Engineering‘s STEM pipeline capacity with this type of research, collaboration and data management engagement.

Processing And Characterization Of Zr-Based Metallic Glass By Laser Direct Depositon, Heehun Bae

Open Access Theses

Bulk Metallic Glass has become famous for its exceptional mechanical and corrosion properties. Especially, Zirconium has been the prominent constituent in Bulk Metallic Glass due to its superior glass forming ability, the ability to form amorphous phase with low cooling rate, thereby giving advantages in structural applications.

In this study, Zirconium powder was alloyed with Aluminum, Nickel and Copper powder at an atomic ratio of 65:10:10:15, respectively. Using the ball milling process to mix the powders, Zr65 Al10 Ni 10 Cu15 amorphous structure was manufactured by laser direct deposition.

Laser power and laser scanning speed were optimized to increase the …

Shear Rheological Characterization Of Gel Healing Response And Construction Of Rheo-Piv System, Abhishek Deepak Bawiskar

Open Access Theses

Thermo-reversible gels are solvent-filled 3D networks of polymer chains interconnected by physical (transient) crosslinks. On applying a high shear stress, the crosslinks are broken and these gels show a typical stress-strain behavior due to cohesive fracture of the gel. When heated above a critical temperature and cooled back to room temperature, all the crosslinks are re-formed. Interestingly, partial to full recovery of broken crosslinks is also observed by simply letting the gel stand at room temperature. In this study, the fracture and healing behavior of a model acrylic triblock copolymer gel has been characterized by shear rheometry. A mathematical model …

Phase Field Modeling Of Shear Yielding And Crazing In Glassy Polymer, Yunzhe Mao

Open Access Theses

Glassy polymers are very important in industrial and commercial components manufacturing. For instance, it is used to manufacture polymer-matrix composites, the type of composite used in the Dreamliner 787. But this kind of material is also limited by its tendency to fail in brittle manner. In this study, we use phase field model to characterize the yielding condition of glassy amorphous polymer under a wide range of loading conditions. The main failure mechanisms in amorphous glassy polymers, such as poly-methyl-methacrylate (PMMA), are crazing and shear yielding. Crazing is formed because of the nucleation of micro-voids in the location of stress …

A Framework For Synthesizing Agent-Based Heterogeneous Population Model For Epidemic Simulation, Madih Sahar

Open Access Theses

Social interactions play an important role in spread of a disease. In this thesis we propose a probabilistic approach to synthesize an agent-based heterogeneous population interaction model to study the spatio-temporal dynamics of an air-born epidemic, such as influenza, in a metropolitan area. The proposed methodology is generic in nature and can generate a baseline population for the cities for which detailed population summary tables are not available. The joint probabilities of population demographics are estimated using the International Public Use Microsimulation Data (IPUMS) sample data set. Based on the population density and the socio-economic status, the population is divided …

A Sensor Ontology For The Domain Of Firefighting Robots, Amy Renae Wagoner

Open Access Theses

Fires create thousands of dollars in damage and thousands of deaths each year. Firefighters risk their lives everyday and are often killed in action. Firefighting robots may be able to reduce the loss of lives and damage due to fires. Robots are often used for redundant tasks that require the consistency and efficiency of a machine. They are especially optimal for tasks that require strength that exceeds that of a typical human being or for environments that are hazardous to people. Robots' metallic exteriors are far more durable and easier to replace than flesh and blood, thus they are ideal …