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Articles 1 - 10 of 10
Full-Text Articles in Engineering
Electrostatic Potential And Valence Modulation In La0.7sr0.3mno3 Thin Films, Robbyn Trappen, A. C. Garcia- Castro, Vu Thanh Tra, Chih-Yeh Huang, Wilfredo Ibarra-Hernandez, James Fitch, Sobhit Singh, Jingling Zhou, Guerau Cabrera, Ying-Hao Chu, James M. Lebeau, Aldo H. Romero, Mikel B. Holcomb
Electrostatic Potential And Valence Modulation In La0.7sr0.3mno3 Thin Films, Robbyn Trappen, A. C. Garcia- Castro, Vu Thanh Tra, Chih-Yeh Huang, Wilfredo Ibarra-Hernandez, James Fitch, Sobhit Singh, Jingling Zhou, Guerau Cabrera, Ying-Hao Chu, James M. Lebeau, Aldo H. Romero, Mikel B. Holcomb
Faculty & Staff Scholarship
The Mn valence in thin film La0.7Sr0.3MnO3 was studied as a function of film thickness in the range of 1–16 unit cells with a combination of non-destructive bulk and surface sensitive X-ray absorption spectroscopy techniques. Using a layer-by-layer valence model, it was found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface. These results were supported by first principles calculations. The surface valence increases to up to Mn3.7+, whereas the interface valence reduces down to Mn2.5+. The change in valence from the expected …
Analytical Cpg Model Driven By Limb Velocity Input Generates Accurate Temporal Locomotor Dynamics, Sergiy Yakovenko, Anton Sobinov, Valeriya Gritsenko
Analytical Cpg Model Driven By Limb Velocity Input Generates Accurate Temporal Locomotor Dynamics, Sergiy Yakovenko, Anton Sobinov, Valeriya Gritsenko
Faculty & Staff Scholarship
The ability of vertebrates to generate rhythm within their spinal neural networks is essential for walking, running, and other rhythmic behaviors. The central pattern generator (CPG) network responsible for these behaviors is well-characterized with experimental and theoretical studies, and it can be formulated as a nonlinear dynam- ical system. The underlying mechanism responsible for locomotor behavior can be expressed as the process of leaky integration with resetting states generating appropriate phases for changing body velocity. The low-dimensional input to the CPG model generates the bilateral pattern of swing and stance modulation for each limb and is consistent with the desired …
Fabrication And Thermoelectric Characterization Of Transition Metal Silicide-Based Composite Thermocouples, Gunes A. Yakaboylu, Rajalekshmi C. Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
Fabrication And Thermoelectric Characterization Of Transition Metal Silicide-Based Composite Thermocouples, Gunes A. Yakaboylu, Rajalekshmi C. Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
Faculty & Staff Scholarship
Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi2, WSi2, ZrSi2, or TaSi2 with an additional 10 vol % Al2O3 to form a silicide–oxide composite. The structural and high-temperature thermoelectric properties of the composite thermocouples were examined using X-ray diffraction, scanning electron microscopy and a typical hot–cold junction measurement technique. MoSi2-Al2O3 and WSi2-Al2O3 composites exhibited higher intrinsic Seebeck coefficients (22.2–30.0 μV/K) at high-temperature gradients, which were calculated from the thermoelectric data of …
Interval Fuzzy Model For Robust Aircraft Imu Sensors Fault Detection, Michele Crispoltoni, Mario Luca Fravolini, Fabio Balzano, Stephane D'Urso, Marcello Rosario Napolitano
Interval Fuzzy Model For Robust Aircraft Imu Sensors Fault Detection, Michele Crispoltoni, Mario Luca Fravolini, Fabio Balzano, Stephane D'Urso, Marcello Rosario Napolitano
Faculty & Staff Scholarship
This paper proposes a data-based approach for a robust fault detection (FD) of the inertial measurement unit (IMU) sensors of an aircraft. Fuzzy interval models (FIMs) have been introduced for coping with the significant modeling uncertainties caused by poorly modeled aerodynamics. The proposed FIMs are used to compute robust prediction intervals for the measurements provided by the IMU sensors. Specifically, a nonlinear neural network (NN) model is used as central prediction of the sensor response while the uncertainty around the central estimation is captured by the FIM model. The uncertainty has been also modelled using a conventional linear Interval Model …
Learning Local, Quenched Disorder In Plasticity And Other Crackling Noise Phenomena, Stefanos Papanikolaou
Learning Local, Quenched Disorder In Plasticity And Other Crackling Noise Phenomena, Stefanos Papanikolaou
Faculty & Staff Scholarship
When far from equilibrium, many-body systems display behavior that strongly depends on the initial conditions. A characteristic such example is the phenomenon of plasticity of crystalline and amorphous materials that strongly depends on the material history. In plasticity modeling, the history is captured by a quenched, local and disordered flow stress distribution. While it is this disorder that causes avalanches that are commonly observed during nanoscale plastic deformation, the functional form and scaling properties have remained elusive. In this paper, a generic formalism is developed for deriving local disorder distributions from field- response (e.g., stress/strain) timeseries in models of crackling …
Insights Into The Magnetic Dead Layer In La0.7sr0.3mno3 Thin Films From Temperature, Magnetic Field And Thickness Dependence Of Their Magnetization, N. Mottaghi, M.S. Seehra, R. Trappen, S. Kumari, Chih-Yeh Huang, S. Yousefi, G.B. Cabrera, A.H. Romero, M.B. Holcomb
Insights Into The Magnetic Dead Layer In La0.7sr0.3mno3 Thin Films From Temperature, Magnetic Field And Thickness Dependence Of Their Magnetization, N. Mottaghi, M.S. Seehra, R. Trappen, S. Kumari, Chih-Yeh Huang, S. Yousefi, G.B. Cabrera, A.H. Romero, M.B. Holcomb
Faculty & Staff Scholarship
Experimental investigations of the magnetic dead layer in 7.6 nm thick film of La0.7Sr0.3MnO3 (LSMO) are reported. The dc magnetization (M) measurements for a sample cooled to T = 5 K in applied field H = 0 reveal the presence of negative remanent magnetization (NRM) in the M vs. H (magnetic field) measurements as well as in the M vs. T measurements in H = 50 Oe and 100 Oe. The M vs. T data in ZFC (zero-field-cooled) and FC (field-cooled) protocols are used to determine the blocking temperature TB in different H. Isothermal hysteresis loops at differ- ent T …
Parametric Investigation Of Combustion And Heat Transfer Characteristics Of Oscillating Linear Engine Alternator, Mehar Bade, Nigel N. Clark, Matthew C. Robinson, Parviz Famouri
Parametric Investigation Of Combustion And Heat Transfer Characteristics Of Oscillating Linear Engine Alternator, Mehar Bade, Nigel N. Clark, Matthew C. Robinson, Parviz Famouri
Faculty & Staff Scholarship
An Oscillating Linear Engine Alternator (OLEA) has the potential to overcome the thermal, mechanical, and combustion inadequacies encountered by the conventional slider-crank engines. The linear engines convert the reciprocating piston motion into electricity, thereby eliminating needless crankshaft linkages and rotational motion. As the dead center positions are not explicitly identified unlike crankshaft engines, the linear engine exhibits different stroke and compression ratio every cycle and should manage the unfavorable events like misfire, rapid load changes, and overfueling without the energy storage of a flywheel. Further, the apparatus control and management strategy is difficult for OLEA when compared to conventional engines …
Performance Trades For Multiantenna Gnss Multisensor Attitude Determination Systems, Nathan A. Tehrani, Jason N. Gross
Performance Trades For Multiantenna Gnss Multisensor Attitude Determination Systems, Nathan A. Tehrani, Jason N. Gross
Faculty & Staff Scholarship
We present various performance trades for multiantenna global navigation satellite system (GNSS) multisensor attitude estimation systems. In particular, attitude estimation performance sensitivity to various error sources and system configurations is assessed. This study is motivated by the need for system designers, scientists, and engineers of airborne astronomical and remote sensing platforms to better determine which system configuration is most suitable for their specific application. In order to assess performance trade-offs, the attitude estimation performance of various approaches is tested using a simulation that is based on a stratospheric balloon platform. For GNSS errors, attention is focused on multipath, receiver measurement …
Study Of Material Compatibility For A Thermal Energy Storage System With Phase Change Material, Songgang Qiu, Laura Solomon, Ming Fang
Study Of Material Compatibility For A Thermal Energy Storage System With Phase Change Material, Songgang Qiu, Laura Solomon, Ming Fang
Faculty & Staff Scholarship
The suitability of stainless steel 316L and Inconel 625 for use in a latent heat thermal energy storage (TES) system was investigated. A NaCl–NaF eutectic mixture with a melting temperature of 680 ◦C was used as the phase change material (PCM). Containers were filled with the PCM prior to heating to 750 ◦C, then examined after 100 and 2500 h of high-temperature exposure by analyzing the material surface and cross-section areas. A small amount of corrosion was present in both samples after 100 h. Neither sample suffered significant damage after 2500 h. The undesirable inter-granular grain boundary attack found in …
Air Data Sensor Fault Detection With An Augmented Floating Limiter, Fabio Balzano, Mario Luca Fravolini, Marcello R. Napolitano, Stephane D'Urso, Michele Crispoltoni, Giuseppe Del Core
Air Data Sensor Fault Detection With An Augmented Floating Limiter, Fabio Balzano, Mario Luca Fravolini, Marcello R. Napolitano, Stephane D'Urso, Michele Crispoltoni, Giuseppe Del Core
Faculty & Staff Scholarship
Although very uncommon, the sequential failures of all aircraft Pitot tubes, with the consequent loss of signals for all the dynamic parameters from the Air Data System, have been found to be the cause of a number of catastrophic accidents in aviation history. This paper proposes a robust data-driven method to detect faulty measurements of aircraft airspeed, angle of attack, and angle of sideslip. This approach first consists in the appropriate selection of suitable sets of model regressors to be used as inputs of neural network-based estimators to be used online for failure detection. The setup of the proposed fault …