Engineering Commons^™

Atomic-Layer-Deposited Al2o3 On Bi2te3 For Topological Insulator Field-Effect Transistors, Han Liu, Peide D. Ye

Birck and NCN Publications

We report dual-gate modulation of topological insulator field-effect transistors (TI FETs) made on Bi2Te3 thin flakes with integration of atomic-layer-deposited (ALD) Al2O3 high-k dielectric. Atomic force microscopy study shows that ALD Al2O3 is uniformly grown on this layer-structured channel material. Electrical characterization reveals that the right selection of ALD precursors and the related surface chemistry play a critical role in device performance of Bi2Te3 based TI FETs. We realize both top-gate and bottom-gate control on these devices, and the highest modulation rate of 76.1% is achieved by using simultaneous dual gate control. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622306]

Characterization Of Parallel Application Runtime Sensitivity On Multi-Core High Performance Computing Systems, Padma Priya Veeraraghavan

Purdue Polytechnic Masters Theses

A commonly seen behavior of parallel applications is that their runtime is influenced by network communication load. The way a parallel application is run in a network and the presence of other applications and processes in the network can contribute to a wide range of variations in the runtime. Therefore, in order to achieve consistent and optimal runtimes, it is important to understand and characterize the runtime sensitivity of parallel applications with respect to execution under the presence of network communication load.

In this research, runtime sensitivities for various parallel applications were studied by applying additional network communication load. In …

Miniature Mass Spectrometry: Rf Amplitude Control System Design, Matthew Allen Kirleis

Purdue Polytechnic Masters Theses

This thesis covers the methods used to construct and characterize a custom digital RF amplitude control system. Many types of mass spectrometers exist, but few have been miniaturized as much as the Mini instruments developed at Purdue University. The goal of this research was to improve upon an earlier amplitude control system consisting of analog circuits first implemented in the Mini 11.5 mass spectrometer developed at Purdue University.

A custom set of control and data acquisition electronics were developed for testing the digital and analog control systems in a Mini 11.5 mass spectrometer chassis. A MATLAB Simulink simulation was done …

Automating The Fret Slotting Process Using A Plc Controlled 1.5 Axis Mill, James Stratton

Purdue Polytechnic Masters Theses

Stratton, James A. M.S., Purdue University, August 2011. Automating the Fret Slotting Process Using a PLC Controlled 1.5 Axis CNC Mill. Major Professor: Richard Mark French.

Can automation assist small job shops and hobbyists in the production of stringed instruments? This research set out to answer the question using a quantitative approach to determine if an economical CNC machine could be produced in such a fashion as to seamlessly join the workshop as an affordable, yet precise instrument to aid in the production of stringed instruments. The key was to incorporate common industrial automation equipment into the operation of the …

Do Wind Turbines Affect Weather Conditions?: A Case Study In Indiana, Meghan F. Henschen, Brittany Herrholtz, Lacey Rhudy, Kathryn Demchak, Brian Doogs, Joshua Holland, Erik Larson, Johnny Martin, Matthew Rudkin

The Journal of Purdue Undergraduate Research

Wind turbines are becoming increasingly widespread in the United States as the world looks for cleaner sources of energy. Scientists, policymakers, and citizens have strong opinions regarding the positive and negative effects of wind energy projects, and there is a great deal of misinformation about wind energy circulating on the Web and other media sources. The purpose of this study is to gain a better understanding of how the rotation of hundreds of turbines can influence local weather conditions within a wind farm and in the surrounding areas. This experiment measures temperature, atmospheric pressure, wind speed, wind direction, relative humidity, …

The Future Of Aerospace Propulsion: Visco-Elastic Non-Newtonian Liquids, Nicole Arockiam

The Journal of Purdue Undergraduate Research

Aerospace propulsion often involves the spray and combustion of liquids. When a liquid is sprayed, large drops form first, in a process known as primary atomization. Then, each drop breaks up into smaller droplets, in a process known as secondary atomization. This determines final drop sizes, which affect the liquid’s evaporation and mixing rates and ultimately influence combustor efficiency. Little has been published concerning the secondary atomization of visco-elastic non-Newtonian liquids, such as gels. These substances have special potential as aerospace propellants, because they are safer to handle than their Newtonian liquid counterparts, such as water. Additionally, they can be …

Comparison Of Best Economy And Best Power Mixture Settings In The Purdue University Training Fleet, Charles G. Chrisman

Purdue Polytechnic Directed Projects

Purdue University operates a fleet of Cirrus SR20s as training aircraft. Standard operating procedures for the cruise portion of cross country training flights call for 65% power with a best power mixture, also called rich of peak, as opposed to a best economy setting, also called lean of peak. Previous work demonstrated that fuel consumption rates, cylinder head temperatures, and true airspeeds are lower when best economy is employed compared to best power for the same power output. This study confirmed that best economy is associated with a lower fuel consumption rate and lower cylinder head temperatures but was unable …

Comparison Of Turbine Engine Test Cell Airborne Nanoparticle Count Versus Ambient Background Particle Count, Ryne Larowe

Purdue Polytechnic Directed Projects

With the establishment of the National Test Facility for Aerospace Fuels and Propulsion at Purdue University in October of 2009, new equipment has been acquired to measure and classify exhaust emissions. This facility utilizes the Honeywell F109 turbofan and Pratt & Whitney PT-6 turboprop engine test cells to analyze the emissions and engine operation of new alternative aviation fuels. This observational study investigates what, if any difference there is in the amount of ambient residual Particulate Matter (PM) in the turbofan engine test cell when compared to ambient particle count associated with the Purdue University Airport (KLAF) property. The project …

Stereoscopic Vision's Impact On Spatial Ability Testing, George Takahashi

Purdue Polytechnic Masters Theses

A look into spatial ability testing tools and the variations that past researchers made to focus on key factors that affect test scores, will demonstrate the need for tuning traditional testing methods to accommodate a wider demographic and provide more accurate results. Due to technological limitations of the time, a large variety of past spatial tests were developed by hand-drawings. Within this research, the addition of stereoscopic vision is analyzed to determine the value of said changes on human perception of spatial entities.

Dislocation Pinning Effects Induced By Nano-Precipitates During Warm Laser Shock Peening: Dislocation Dynamic Simulation And Experiments, Yiliang Liao, Chang Ye, Huang Gao, Bong-Joong Kim, Sergey Suslov, Eric A. Stach, Gary J. Cheng

Birck and NCN Publications

Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the …

Periodically Changing Morphology Of The Growth Interface In Si, Ge, And Gap Nanowires, C-Y Wen, J. Tersoff, K. Hillerich, M.C. Reuter, J. H. Park, S. Kodambaka, Eric Stach, F.M. Ross

Birck and NCN Publications

Nanowire growth in the standard < 111 > direction is assumed to occur at a planar catalyst-nanowire interface, but recent reports contradict this picture. Here we show that a nonplanar growth interface is, in fact, a general phenomenon. Both III-V and group IV nanowires show a distinct region at the trijunction with a different orientation whose size oscillates during growth, synchronized with step flow. We develop an explicit model for this structure that agrees well with experiment and shows that the oscillations provide a direct visualization of catalyst supersaturation. We discuss the implications for wire growth and structure.

A Digital Hydraulic Valve, Actuated Using A Piezoelectric Linear Motor, Brian C. Bevill

Purdue Polytechnic Directed Projects

Proportional control in hydraulics is widely utilized. The most widely used current types of proportional valves utilize solenoid technology. While this technology has been around for decades and has been proven an effective means of control, there is always a demand for improved performance of advancing technologies. Integrating piezoelectric devices as a means to control hydraulic systems helps advance control for hydraulic systems.

Piezoelectric stack devices have been used to control hydraulic systems with success. Advantages of these stacks include being relatively small with a high power to weight ratio, using less energy than solenoid operations, and being fast acting. …

Direct Simulation Monte Carlo Study Of Effects Of Thermal Nonuniformities In Electron-Beam Physical Vapor Deposition, A. Venkattraman, Alina A. Alexeenko

Birck and NCN Publications

In a typical electron-beam physical vapor deposition system, there is limited control over how the high-power electron beam heats the metal surface. This leads to thermal nonuniformities at the melt. Three-dimensional direct simulation Monte Carlo simulations were performed with the aim of quantifying the effect of such spatial variations of source temperature in thin film depositions using an electron-beam physical vapor deposition system. The source temperature distribution from a typical deposition process was used in the direct simulation Monte Carlo simulations performed for various mass flow rates. The use of an area-averaged temperature is insufficient for all mass flow rates …

Schottky-Barrier Height Modulation Of Metal/In0.53ga0.47as Interfaces By Insertion Of Atomic-Layer Deposited Ultrathin Al2o3, Runsheng Wang, Min Xu, Peide D. Ye, Ru Huang

Birck and NCN Publications

The improvement of the metal/InGaAs interface is essential for the future application of InGaAs metal source/drain Schottky-barrier metal-oxide-semiconductor field-effect-transistors. In this article, on In0.53Ga0.47As, the authors examine the recently proposed method of inserting an ultrathin insulator to modulate the effective Schottky-barrier height (SBH) at the metal/semiconductor interface. Both n-type and p-type In0.53Ga0.47As are investigated by inserting an atomic-layer deposited Al2O3 interlayer. The results indicate that SBH modulation is more effective at the n-InGaAs interface than the p-InGaAs interface for the same Al2O3 thickness. However, the Fermi level at the metal/InGaAs interface is still weakly pinned even after inserting 2 nm …

Numerical Modeling Of Plasmonic Nanoantennas With Realistic 3d Roughness And Distortion, Alexander V. Kildishev, Joshua D. Borneman, Kuo-Ping Chen, Vladimir P. Drachev

Birck and NCN Publications

Nanostructured plasmonic metamaterials, including optical nanoantenna arrays, are important for advanced optical sensing and imaging applications including surface-enhanced fluorescence, chemiluminescence, and Raman scattering. Although designs typically use ideally smooth geometries, realistic nanoantennas have nonzero roughness, which typically results in a modified enhancement factor that should be involved in their design. Herein we aim to treat roughness by introducing a realistic roughened geometry into the finite element (FE) model. Even if the roughness does not result in significant loss, it does result in a spectral shift and inhomogeneous broadening of the resonance, which could be critical when fitting the FE simulations …

Development Of Guidelines For The Rating, Inspection, And Acquisition Of Railroad Flatcars For Use As Highway Bridges On Low-Volume Roads, Jason T. Provines, Robert Connor

Indiana Local Technical Assistance Program (LTAP) Technical Reports

Due to budget constraints, many state and county highway agencies are often forced to develop innovative and economical rehabilitation strategies for deteriorated bridges. One such option is to use a retired railroad flatcar for a bridge superstructure. Railroad flatcars can be found in many lengths, making them versatile options for replacing bridges of a range of span lengths up to about 90 feet. Railroad flatcars are also completely modular and lightweight, allowing for quick construction. Within Indiana, as well as other states, several of these bridge structures have been in service for many years.

Although their performance has been satisfactory, …

Estimating Highway Maintenance Work, Fifth Edition, Ohio Department Of Transportation, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Publications

This manual is founded upon a problem index that walks through a number of equations that will estimate the maintenance work required in areas such as bridge deck repair, chip and seal, crack sealing, mowing, road salt application, salt spreader calibration, and many more everyday road maintenance operations. The manual also includes an appendix to help with lengths, areas, volumes, rates, equivalents, and rules.

Virtual Prototyping Of A Mechatronics Device, Ryne P. Mchugh

Purdue Polytechnic Directed Projects

Mechanical, electrical, and embedded software engineering are being combined in modern products. This combination has come to be known as mechatronics. The high level of multidisciplinary interaction makes it difficult for collaboration and use of computers in Mechatronics’ design.

Dassault Systems’ SolidWorks and National Instruments’ LabVIEW are industrial grade softwares that can be used in the development and deployment phase of engineering design. SolidWorks is used for physical modeling and analysis of geometric parts, while LabVIEW is used as a programming language for control logic and data acquisition. National Instruments has developed a module, known as SoftMotion, which allows communication …

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 …

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 …

Quantifying Multiple Types Of Damping Acting On Bronze-Wound Guitar Strings, Jonathan Christian

Purdue Polytechnic Masters Theses

The goal of this study was to quantify the contributions of multiple damping types acting on guitar strings for each mode over a wide frequency range so that design variables could be identified to one day create frequency based damping in guitar strings. Structural dynamic testing was used to obtain the time-response of a vibrating string in open air and in a vacuum. From this signal, each harmonic was filtered and the decay envelope was curve-fitted with a function that was a linear summation of decay functions. From the curve-fits, the damping coefficients for aerodynamic, friction, and material damping were …

Room Temperature Device Performance Of Electrodeposited Insb Nanowire Field Effect Transistors, Suprem Das, Collin J. Delker, Dmitri Zakharov, Yong P. Chen, Timothy D. Sands, David B. Janes

Birck and NCN Publications

InSb nanowires have been formed by electrodeposition in porous anodic alumina templates and employed as transistor channels. The 100 nm diameter nanowires had a zinc blende crystal structure. Single-nanowire field-effect transistors (NW-FETs) with a channel length of 500 nm exhibited on-currents of similar to 40 mu A, on/off ratios of similar to 16-20, drain conductances of similar to 71 mu S and field-effect electron mobility of similar to 1200 cm(2) V(-1) s(-1). Compared with reported NW-FETs, the on-current is large and the current saturation occurs at low source-drain voltages. These characteristics can be understood in terms of velocity saturation effects …

Dynamics Of Entanglement In A Two-Dimensional Spin System, Qing Xu, Gehad Sadiek, Sabre Kais

Birck and NCN Publications

We consider the time evolution of entanglement in a finite two-dimensional transverse Ising model. The model consists of a set of seven localized spin-1/2 particles in a two-dimensional triangular lattice coupled through nearest-neighbor exchange interaction in the presence of an external time-dependent magnetic field. The magnetic field is applied in different function forms: step, exponential, hyperbolic, and periodic. We found that the time evolution of the entanglement shows an ergodic behavior under the effect of the time-dependent magnetic fields. Also, we found that while the step magnetic field causes great disturbance to the system, creating rapid oscillations, the system shows …

Comparison Of Photothermal And Piezoacoustic Excitation Methods For Frequency And Phase Modulation Atomic Force Microscopy In Liquid Environments, A. Labuda, K. Kobayashi, Daniel Kiracofe, K. Suzuki, P. H. Gruetter, H. Yamada

Birck and NCN Publications

In attempting to perform frequency modulation atomic force microscopy (FM-AFM) in liquids, a non-flat phase transfer function in the self-excitation system prevents proper tracking of the cantilever natural frequency. This results in frequency-and-phase modulation atomic force microscopy (FPM-AFM) which lies in between phase modulation atomic force microscopy (PM-AFM) and FM-AFM. We derive the theory necessary to recover the conservative force and damping in such a situation, where standard FM-AFM theory no longer applies. Although our recovery procedure applies to all cantilever excitation methods in principle, its practical implementation may be difficult, or even impossible, if the cantilever is driven piezoacoustically. …

Formation Of Silicon Nanodots Via Ion Beam Sputtering Of Ultrathin Gold Thin Film Coatings On Si, Osman El-Atwani, Sami Ortoleva, Alex Cimaroli, Jean Paul Allain

Birck and NCN Publications

Ion beam sputtering of ultrathin film Au coatings used as a physical catalyst for self-organization of Si nanostructures has been achieved by tuning the incident particle energy. This approach holds promise as a scalable nanomanufacturing parallel processing alternative to candidate nanolithography techniques. Structures of 11- to 14-nm Si nanodots are formed with normal incidence low-energy Ar ions of 200 eV and fluences above 2 x 10(17) cm(-2). In situ surface characterization during ion irradiation elucidates early stage ion mixing migration mechanism for nanodot self-organization. In particular, the evolution from gold film islands to the formation of ion-induced metastable gold silicide …