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Articles 541 - 570 of 1144
Full-Text Articles in Mechanical Engineering
Planning Freeform Extrusion Fabrication Processes With Consideration Of Horizontal Staircase Effect, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers
Planning Freeform Extrusion Fabrication Processes With Consideration Of Horizontal Staircase Effect, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An algorithm has been developed to estimate the “horizontal” staircase effect and a technique is proposed to reduce this type of geometrical error for freeform extrusion fabrication processes of 3D “solid” parts. The adaptive rastering technique, proposed in this paper, analyzes the geometry of each layer and changes the width of each line of the raster adaptively in order to reduce the staircase error and increase the productivity simultaneously. For each line, the maximum width that results in a staircase error smaller than a predefined threshold is determined for decreasing the fabrication time or increasing the dimensional accuracy, or both. …
A Framework For Large Scale Fused Pellet Modeling (Fpm) By An Industry Robot, Zhiyuan Wang, Renwei Liu, Todd E. Sparks, Frank W. Liou
A Framework For Large Scale Fused Pellet Modeling (Fpm) By An Industry Robot, Zhiyuan Wang, Renwei Liu, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fused pellet modeling (FPM) is an important method in additive manufacturing technology, where granular material is used instead of filaments. In FPM, prototypes are constructed by the sequential deposition of material layers. As the size of the part increases, the problem of long build times and part deformation becomes critical. In this paper, methods for eliminating the void density during deposition and accuracy control principles for large scale FPM processes are studied. By analyzing the ab initio principles of this process, a mini extruder with variable pitch and progressive diameter screw for the large scale fused deposition is proposed. Based …
Consensus With Reduced Communication Links Via Relative Neighboring Velocity Information, Gerardo De La Torre, Tansel Yucelen
Consensus With Reduced Communication Links Via Relative Neighboring Velocity Information, Gerardo De La Torre, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper, a consensus protocol is introduced to virtually manipulate the communication topology of a given networked multiagent system - without adding physical edges to the graph. The proposed protocol achieves this objective by utilizing not only neighboring agents' relative position information but also their possibly delayed velocity information. It is shown that the stability of the proposed framework is not dependent on the possible time delay present in the neighboring velocity information. In addition, it is formally proven that utilization of the proposed consensus protocol is equivalent to the addition of virtual communication links in a standard consensus …
Adaptive Control With Nonlinear Reference Systems, Tansel Yucelen, Benjamin Gruenwald, Jonathan A. Muse, Gerardo De La Torre
Adaptive Control With Nonlinear Reference Systems, Tansel Yucelen, Benjamin Gruenwald, Jonathan A. Muse, Gerardo De La Torre
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Although reference systems with linear dynamics are common in the adaptive control literature, they can lead to limitations on the achievable closed-loop dynamical system performance. This is due to the fact that linear reference systems can only approximate the desired closed-loop behavior of nonlinear dynamical systems in narrow regions of the state-space. In this paper, we study a new adaptive control architecture for uncertain dynamical systems based on a nonlinear reference system. It is shown that the system error between the uncertain dynamical system and the nonlinear reference system asymptotically vanishes in steady-state, and its performance is guaranteed during the …
Exploitation Of Heterogeneity In Distributed Sensing: An Active-Passive Networked Multiagent Systems Approach, John Daniel Peterson, Tansel Yucelen, Girish Chowdhary, Suresh Kannan
Exploitation Of Heterogeneity In Distributed Sensing: An Active-Passive Networked Multiagent Systems Approach, John Daniel Peterson, Tansel Yucelen, Girish Chowdhary, Suresh Kannan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Most distributed sensing methods assume that the expected value of sensed information is same for all agents - ignoring differences in sensor capabilities due to, for example, environmental factors and sensors' quality and condition. In this paper, we present a distributed sensing framework to exploit heterogeneity in information provided about a dynamic environment using an active-passive networked multiagent systems approach. Specifically, this approach consists of agents subject to exogenous inputs (active agents) and agents without any inputs (passive agents). In addition, if an active agent senses a quantity accurately (resp., not accurately), then it is weighted high (resp., low) in …
Analysis And Design Of Adaptive Control Systems With Unmodeled Input Dynamics Via Multiobjective Convex Optimization, Mario Luca Fravolini, Tansel Yucelen, Jonathan Muse, Paolo Valigi
Analysis And Design Of Adaptive Control Systems With Unmodeled Input Dynamics Via Multiobjective Convex Optimization, Mario Luca Fravolini, Tansel Yucelen, Jonathan Muse, Paolo Valigi
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A challenging problem for adaptive control systems is the accurate characterization of the transient response in the presence of dynamic uncertainties such as a partially known actuator. Considering an actuator modelled as a first order filter with an uncertain control effectiveness and using a projection mechanism for parameters adaptation, we show that the tracking error dynamics behaves as a linear system perturbed by bounded uncertainties. This brings the advantage that the stability analysis can be cast in terms of LMIs so that convex optimization tools can be used for analysis and design. In this framework we propose a mixed linear/adaptive …
Aluminum Plasmonic Metamaterials For Structural Color Printing, F. Cheng, Jie Gao, L. Stan, D. Rosenmann, D. Czaplewski, Xiaodong Yang
Aluminum Plasmonic Metamaterials For Structural Color Printing, F. Cheng, Jie Gao, L. Stan, D. Rosenmann, D. Czaplewski, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Real-Time Monitoring Of Laser Powder Bed Fusion Process Using High-Speed X-Ray Imaging And Diffraction, C. Zhao, K. Fezzaa, R. W. Cunningham, H. Wen, F. De Carlo, Lianyi Chen, A. D. Rollett, T. Sun
Real-Time Monitoring Of Laser Powder Bed Fusion Process Using High-Speed X-Ray Imaging And Diffraction, C. Zhao, K. Fezzaa, R. W. Cunningham, H. Wen, F. De Carlo, Lianyi Chen, A. D. Rollett, T. Sun
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Structural Color Printing Based On Plasmonic Metasurfaces Of Perfect Light Absorption, F. Cheng, Jie Gao, T. S. Luk, Xiaodong Yang
Structural Color Printing Based On Plasmonic Metasurfaces Of Perfect Light Absorption, F. Cheng, Jie Gao, T. S. Luk, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Slip Length Crossover On A Graphene Surface, Zhi Liang, Pawel Keblinski
Slip Length Crossover On A Graphene Surface, Zhi Liang, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Equilibrium and Non-Equilibrium Molecular Dynamics Simulations, We Study the Flow of Argon Fluid above the Critical Temperature in a Planar Nanochannel Delimited by Graphene Walls. We Observe that, as a Function of Pressure, the Slip Length First Decreases Due to the Decreasing Mean Free Path of Gas Molecules, Reaches the Minimum Value When the Pressure is Close to the Critical Pressure, and Then Increases with Further Increase in Pressure. We Demonstrate that the Slip Length Increase at High Pressures is Due to the Fact that the Viscosity of Fluid Increases Much Faster with Pressure Than the Friction Coefficient between …
Control Of Fluid Dynamics By Nanoparticles In Laser Melting, Chao Ma, Lianyi Chen, Jiaquan Xu, Jingzhou Zhao, Xiaochun Li
Control Of Fluid Dynamics By Nanoparticles In Laser Melting, Chao Ma, Lianyi Chen, Jiaquan Xu, Jingzhou Zhao, Xiaochun Li
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Effective control of fluid dynamics is of remarkable scientific and practical significance. It is hypothesized that nanoparticles could offer a novel means to control fluid dynamics. In this study, laser melting was used to investigate the feasibility of tuning fluid dynamics by nanoparticles and possibly breaking existing limits of conventional laser processing techniques. Alumina nanoparticles reinforced nickel samples, fabricated through electrocodeposition, were used for laser melting experiments. Since the melt pool surface is controlled by the fluid dynamics, surface topographies were carefully studied to reveal the nanoparticle effect on the fluid dynamics. Characterizations of surface topographies and microstructures of pure …
An Interoperable System For Automated Diagnosis Of Cardiac Abnormalities From Electrocardiogram Data, Thidarat Tinnakornsrisuphap, Richard E. Billo
An Interoperable System For Automated Diagnosis Of Cardiac Abnormalities From Electrocardiogram Data, Thidarat Tinnakornsrisuphap, Richard E. Billo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electrocardiogram (ECG) data are stored and analyzed in different formats, devices, and computer platforms. As a result, ECG data from different monitoring devices cannot be displayed unless the user has access to the proprietary software of each particular device. This research describes an ontology and encoding for representation of ECG data that allows open exchange and display of ECG data in a web browser. The ontology is based on the Health Level Seven (HL7) medical device communication standard. It integrates ECG waveform data, HL7 standard ECG data descriptions, and cardiac diagnosis rules, providing a capability to both represent ECG waveforms …
Effect Of A Dc Preionization Source On Energy Deposition In A Pulsed Inductive Plasma, Ryan A. Pahl, Joshua L. Rovey
Effect Of A Dc Preionization Source On Energy Deposition In A Pulsed Inductive Plasma, Ryan A. Pahl, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Time-Resolved Argon Theta-Pinch Plasma Properties By Line Ratio Method With Collisional-Radiative Model, Warner C. Meeks, Joshua L. Rovey
Time-Resolved Argon Theta-Pinch Plasma Properties By Line Ratio Method With Collisional-Radiative Model, Warner C. Meeks, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Electrospray Of An Energetic Ionic Liquid Monopropellant For Multi-Mode Micropropulsion Applications, Steven P. Berg, Joshua L. Rovey, Benjamin D. Prince, Shawn W. Miller, Raymond J. Bemish
Electrospray Of An Energetic Ionic Liquid Monopropellant For Multi-Mode Micropropulsion Applications, Steven P. Berg, Joshua L. Rovey, Benjamin D. Prince, Shawn W. Miller, Raymond J. Bemish
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The multi-mode chemical-electric propulsion capable energetic ionic liquid propellant [Emim][EtSO4]-HAN is electro sprayed in a 100 µm capillary emitter to test the electric-mode performance of the propellant. The ionic liquid exhibits stable electrospray emission in both cation and anion extraction modes at a nominal extraction voltage of 3400 V. Near field measurements of current and mass flow rate distribution are taken at flow rates from 0.19 nL/s to 3.06 nL/s. Total emission current, as measured by Faraday cup and integrated, increases from 754 nA to 3195 nA for cation emission and from 552 nA to 2012 nA for anion emission. …
Performance Oriented Adaptive Architectures With Guaranteed Bounds, Benjamin Gruenwald, Tansel Yucelen, Mario Fravolini
Performance Oriented Adaptive Architectures With Guaranteed Bounds, Benjamin Gruenwald, Tansel Yucelen, Mario Fravolini
Mechanical and Aerospace Engineering Faculty Research & Creative Works
While adaptive control has been used in numerous applications to achieve given system stabilization or command following criteria, the ability to obtain a predictable transient performance is a challenging problem when there is no a priori knowledge about system uncertainties (e.g., their upper bounds and/or domains). In order to address this problem, a new method is presented in [1, 2] utilizing artificial basis functions in the update law of an adaptive control design. This approach is predicated on a gradient minimization procedure and achieves a predictable transient performance without inducing oscillations in the system response as the constant gain due …
Directional Thermal Emission From A Leaky-Wave Frequency-Selective Surface, Edward C. Kinzel, J. C. Ginn, L. A. Florence, B. A. Lail, G. D. Boreman
Directional Thermal Emission From A Leaky-Wave Frequency-Selective Surface, Edward C. Kinzel, J. C. Ginn, L. A. Florence, B. A. Lail, G. D. Boreman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Stochastic Interdigitation As A Toughening Mechanism At The Interface Between Tendon And Bone, Y. Hu, Victor Birman, A. Demyier-Black, A. G. Schwartz, S. Thomopoulos, G. M. Genin
Stochastic Interdigitation As A Toughening Mechanism At The Interface Between Tendon And Bone, Y. Hu, Victor Birman, A. Demyier-Black, A. G. Schwartz, S. Thomopoulos, G. M. Genin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Fano Resonances Realized In Thz Metamaterials Composed Of Continuous Metallic Wires And Split Ring Resonators, Z. Li, S. Cakmakyapan, B. Butun, C. Daskalaki, S. Tzortzakis, Xiaodong Yang, E. Ozbay
Fano Resonances Realized In Thz Metamaterials Composed Of Continuous Metallic Wires And Split Ring Resonators, Z. Li, S. Cakmakyapan, B. Butun, C. Daskalaki, S. Tzortzakis, Xiaodong Yang, E. Ozbay
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara, Greg Hilmas, William Fahrenholtz
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara, Greg Hilmas, William Fahrenholtz
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Solid Waste As Renewable Source Of Energy: Current And Future Possibility In Libya, Tarek A. Hamad, Abdulhakim A. Agll, Yousif M. Hamad, John W. Sheffield
Solid Waste As Renewable Source Of Energy: Current And Future Possibility In Libya, Tarek A. Hamad, Abdulhakim A. Agll, Yousif M. Hamad, John W. Sheffield
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Solid waste holds the greatest potential as biomass source in Libya. The rapid expansion of industry has led to increased urbanization and growing population. These factors have dramatically increased the amount of MSW (municipal solid waste) generated in Libya. However, issues related to environmentally sound MSW management - including waste decrease and clearance - have not been addressed sufficiently. This study presents an overview on solid waste that can be used as a source of bioenergy in Libya including MSW, ISW (industrial solid waste), and HSW (health care wastes) as biomass sources. The management of solid waste and valorization is …
Study Of Energy Recovery And Power Generation From Alternative Energy Source, Abdulhakim Amer A. Agll, Yousif M. Hamad, Tarek A. Hamad, John W. Sheffield
Study Of Energy Recovery And Power Generation From Alternative Energy Source, Abdulhakim Amer A. Agll, Yousif M. Hamad, Tarek A. Hamad, John W. Sheffield
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The energy requirement pattern of world is growing up and developing technology. The available sources, while exhausting and not friendly to the environment, are highly used. Looking at partial supply and different options of environment problems associated with usage, renewable energy sources are getting attention. MSW (Municipal solid waste) composition data had been collected from 1997 to 2009, in Benghazi Libya, to evaluate the waste enthalpy. An incinerator with capacity of 47,250 kg/h was confirmed to burn all the quantity of waste generated by the city through the next 15 years. Initial study was performed to investigate energy flow and …
Stress Amplification During Development Of The Tendon-To-Bone Attachment, Y. Liu, A. G. Schwartz, Victor Birman, S. Thomopoulos, G. M. Genin
Stress Amplification During Development Of The Tendon-To-Bone Attachment, Y. Liu, A. G. Schwartz, Victor Birman, S. Thomopoulos, G. M. Genin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Design Of A Frequency-Selective Surface Strain Sensor, Edward C. Kinzel
Design Of A Frequency-Selective Surface Strain Sensor, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Frequency Selective Surfaces (FSS) have long been used in the RF/microwave community to control radar cross-section. The scattering parameters of the FSS form a signature which is a function of the frequency, element size and spacing, as well as the local electromagnetic environment. This paper considers a FSS as a strain sensor on the surface of a structural element. By interrogating the FSS with a series of polarized far-field measurements in a bistatic configuration the biaxial plane strain, including shear, can be resolved.
The Effects Of Electrode Size And Configuration On Plasma Actuator Thrust And Effectiveness At Low Pressure, Paul Daniel Friz, Joshua L. Rovey
The Effects Of Electrode Size And Configuration On Plasma Actuator Thrust And Effectiveness At Low Pressure, Paul Daniel Friz, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Experimental Characterization Of Optical Nonlocalities In Metal-Dielectric Multilayer Metamaterials, L. Sun, F. Cheng, C. J. Mathai, S. Gangopadhyay, Jie Gao, Xiaodong Yang
Experimental Characterization Of Optical Nonlocalities In Metal-Dielectric Multilayer Metamaterials, L. Sun, F. Cheng, C. J. Mathai, S. Gangopadhyay, Jie Gao, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Finite-Size Effects On Molecular Dynamics Interfacial Thermal-Resistance Predictions, Zhi Liang, Pawel Keblinski
Finite-Size Effects On Molecular Dynamics Interfacial Thermal-Resistance Predictions, Zhi Liang, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Molecular Dynamics Simulations, We Study the Role of Finite Size Effects on the Determination of Interfacial Thermal Resistance between Two Solids Characterized by High Phonon Mean Free Paths. in Particular, We Will Show that a Direct, Heat Source-Sink Method Leads to Strong Size Effect, Associated with Ballistic Phonon Transport to and From, and Specular Reflections at the Simulation Domain Boundary. Lack of Proper Account for These Effects Can Lead to Incorrect Predictions About the Role of Interfacial Bonding and Structure on Interfacial Thermal Resistance. We Also Show that the Finite Size Effect Can Be Dramatically Reduced by Introduction of …
Thermal Transport Across A Substrate-Thin-Film Interface: Effects Of Film Thickness And Surface Roughness, Zhi Liang, Kiran Sasikumar, Pawel Keblinski
Thermal Transport Across A Substrate-Thin-Film Interface: Effects Of Film Thickness And Surface Roughness, Zhi Liang, Kiran Sasikumar, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Molecular Dynamics Simulations and a Model AlN-GaN Interface, We Demonstrate that the Interfacial Thermal Resistance RK (Kapitza Resistance) between a Substrate and Thin Film Depends on the Thickness of the Film and the Film Surface Roughness When the Phonon Mean Free Path is Larger Than Film Thickness. in Particular, When the Film (External) Surface is Atomistically Smooth, Phonons Transmitted from the Substrate Can Travel Ballistically in the Thin Film, Be Scattered Specularly at the Surface, and Return to the Substrate Without Energy Transfer. If the External Surface Scatters Phonons Diffusely, Which is Characteristic of Rough Surfaces, RK is Independent …
A Mechanical Testing Methodology For Additive Manufacturing Processes, Sujitkumar Dongare, Todd E. Sparks, Joseph William Newkirk, Frank W. Liou
A Mechanical Testing Methodology For Additive Manufacturing Processes, Sujitkumar Dongare, Todd E. Sparks, Joseph William Newkirk, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Most additive manufacturing processes are layer-by-layer deposition, thus its mechanical properties could be very different than those made from traditional manufacturing processes. This paper summarizes a mini-tensile testing methodology for additive manufacturing. Research concerning the tensile testing of metallic material has been conducted and test methods have been defined. It encompasses the methods for determination of yield strength, yield point elongation, tensile strength, elongation, and reduction of area. The study of positional variation and cooling-rate dependency in case of additive manufacturing proves to be expensive and time consuming with the full-size test specimens. Thus, this paper discussed a technique for …
Investigation Of Forged-Like Microstructure Produced By A Hybrid Manufacturing Process, Romy Francis, Joseph William Newkirk, Frank W. Liou
Investigation Of Forged-Like Microstructure Produced By A Hybrid Manufacturing Process, Romy Francis, Joseph William Newkirk, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition (LMD) is an additive manufacturing technique for manufacturing complex near net shaped components. The grain size of the typical deposition microstructure in case of Ti-6Al-4V can range between 100µm-600µm, which is much larger than that of forged-like microstructures. Friction Stir Processing (FSP) has been investigated as a method for surface modification to form refined microstructure at the surface of the Ti-6Al-4V components manufactured from the LMD method. Integration of FSP and LMD can greatly improve the product properties. Friction stir processing of the laser deposited Ti-6Al-4V deposits was performed and optimum processing parameters were obtained using this …