Active-Passive Networked Multiagent Systems,
2014
Missouri University of Science and Technology
Active-Passive Networked Multiagent Systems, Tansel Yucelen, John Daniel Peterson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper introduces an active-passive networked multiagent system framework, which consists of agents subject to exogenous inputs (active agents) and agents without any inputs (passive agents) and analyze its convergence using Lyapunov stability. Apart from the existing relevant literature, where either none of the agents are subject to exogenous inputs (i.e., average consensus problem) or all agents are subject to these inputs (i.e., dynamic average consensus problem), the key feature of our approach is that the states of all agents converge to the average of the exogenous inputs applied only to the active agents, where these inputs may or may …
Assessment Of Multi-Mode Spacecraft Micropropulsion Systems,
2014
Missouri University of Science and Technology
Assessment Of Multi-Mode Spacecraft Micropropulsion Systems, Steven P. Berg, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multi-mode spacecraft micro propulsion systems which include a high-thrust chemical mode and high-specific impulse electric mode are assessed with specific reference to cube sat-sized satellite applications. Both cold gas Freon-14 propellant and ionic liquid chemical monopropellant modes were investigated alongside pulsed plasma, electrospray, and helicon electric thruster modes. Systems involving chemical monopropellants have the highest payload mass fractions for a reference mission of a 500 m/s delta-V and 6U sized cube sat for electric propulsion usage below 55% of total delta-V. For higher electric propulsion usage, cold gas thrusters delivered a higher payload mass fraction due to lower system inert …
Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models,
2014
Missouri University of Science and Technology
Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models, Mehrdad Pakmehr, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper develops a new model reference adaptive control approach for uncertain systems with gain scheduled reference models in a multi-input multi-output (MIMO) setting. Specifically, adaptive state feedback for output tracking control problem of MIMO nonlinear systems is studied and gain scheduled reference model system is used for generating desired state trajectories. Using convex optimization tools, a single Lyapunov matrix is computed for multiple linearization's near equilibrium and non-equilibrium points of the nonlinear closed loop gain scheduled reference system. This approach guarantees stability of the closed loop gain scheduled system. Adaptive state feedback control scheme is then developed, and its …
Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models And Constrained Control Inputs,
2014
Missouri University of Science and Technology
Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models And Constrained Control Inputs, Mehrdad Pakmehr, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper develops a new state feedback model reference adaptive control approach for uncertain systems with gain scheduled reference models in a multi-input multi-output (MIMO) setting with constrained control inputs. A single Lyapunov matrix is computed for multiple linearization of the nonlinear closed loop gain scheduled reference system, using convex optimization tools. This approach guarantees stability of the closed loop gain scheduled reference model. Adaptive state feedback control architecture is then developed, and its stability is proven for the case with constrained control inputs. The resulting closed-loop system is shown to have bounded solutions with bounded tracking error, with the …
Decentralized Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models,
2014
Missouri University of Science and Technology
Decentralized Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models, Mehrdad Pakmehr, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Control theoretic concepts for decentralized adaptive control of uncertain systems with gain scheduled reference model is developed. For each subsystem a single Lyapunov matrix is computed, using convex optimization tools, for multiple linearization near equilibrium and non-equilibrium points of the nonlinear closed loop gain scheduled reference subsystem. This approach guarantees stability of the closed loop gain scheduled reference model. Then, decentralized adaptive state feedback control architecture is developed and its stability is proved. Specifically, the resulting closed-loop system is shown to have bounded solutions with bounded tracking error for all the subsystems. Simulation results for two different models of a …
Adaptive Architectures For Distributed Control Of Modular Systems,
2014
Missouri University of Science and Technology
Adaptive Architectures For Distributed Control Of Modular Systems, Tansel Yucelen, Jeff S. Shamma
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We consider the distributed control of large-scale modular systems, i.e., systems consist of physically interconnected (and possibly heterogeneous) submodules that use local information to achieve a given set of global objectives. A graph-theoretic approach is used to model the unknown physical interactions between submodules and utilize an adaptive control algorithm to learn and cancel the effect of such interactions as well as the submodule-level modeling uncertainties asymptotically by allowing submodules to locally communicate with each other through the graph. The key feature of our framework is to bound the mismatch error between the actual and desired closed-loop modular system performance …
Proper Orthogonal Decomposition Technique For Sub-Optimal Control Of Flexible Aircraft Wings Using Discrete Actuators,
2014
Missouri University of Science and Technology
Proper Orthogonal Decomposition Technique For Sub-Optimal Control Of Flexible Aircraft Wings Using Discrete Actuators, M. Kumar, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Distributed parameter systems are, generally, described by a set of partial differential equations. Control design of these systems is a very complex task as compared to that of the lumped parameter systems that are defined by a set of ordinary differential equations. In this paper, we present a stabilizing state-feedback control design approach for a class of second order system, where the system can be controlled by discrete actuators in the spatial domain. The control methodology is developed by combining the technique of 'Proper Orthogonal Decomposition' and Approximate Dynamic Programming. The Proper Orthogonal Decomposition technique is utilized to obtain a …
Resilient Networked Multiagent Systems: A Distributed Adaptive Control Approachy,
2014
Missouri University of Science and Technology
Resilient Networked Multiagent Systems: A Distributed Adaptive Control Approachy, Gerardo De La Torre, Tansel Yucelen, John Daniel Peterson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Control algorithms of networked multiagent systems are generally computed distributivity without having a centralized entity monitoring the activity of agents; and therefore, adverse events such as attacks to the communication network and/or failure of agent-wise components can easily result in system instability and prohibit the accomplishment of system-level objectives. This paper studies resilient coordination of networked multiagent systems in the presence of misbehaving agents, i.e., agents that are subject to such adverse events. In particular, we consider a class of adverse conditions consisting of exogenous disturbances and interagent uncertainties and present a distributed adaptive control architecture to retrieve the nominal …
Decomposition Of Ionic Liquid Ferrofluids For Multi-Mode Spacecraft Propulsion,
2014
Missouri University of Science and Technology
Decomposition Of Ionic Liquid Ferrofluids For Multi-Mode Spacecraft Propulsion, Steven P. Berg, Brynne Coleman, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Ionic liquid ferrofluids based on mixtures of [Emim][EtSO4] and [Bmim][NO3] fuels and hydroxylammonium nitrate oxidizer were synthesized by adding iron oxide nanoparticles. The resulting propellants were then tested for decomposition capability. Spot plate testing indicated that the temperature required to initiate rapid decomposition dropped from 115 °C to 75 °C with a 30% by weight addition of iron oxide for the [Bmim][NO3] propellant. Adding more iron oxide resulted in an increase in onset temperature. The [Emim][EtSO4] propellant had a much lower decrease in onset temperature, bottoming out at 90 °C. Batch reactor tests under vacuum showed that 10% addition of …
Reference Control Architecture In The Presence Of Measurement Noise And Actuator Dynamics,
2014
Missouri University of Science and Technology
Reference Control Architecture In The Presence Of Measurement Noise And Actuator Dynamics, Gerardo De La Torre, Tansel Yucelen, Eric Johnson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper the command governor-based model reference control architecture is developed and analyzed for uncertain dynamical systems in the presence measurement noise and actuator dynamics. Specifically, the command governor is a dynamical system that adjusts the trajectory of a given command in order to enable an uncertain system to be able to follow an ideal reference system capturing a desired closed-loop dynamical system behavior both in transient-time and steady-state. In this paper, we present modifications to the original command governor approach in order to increase its robustness properties against measurement noise and actuator dynamics. In particular, the modified architecture …
Control-Oriented Modeling Of Laser Metal Deposition As A Repetitive Process,
2014
Missouri University of Science and Technology
Control-Oriented Modeling Of Laser Metal Deposition As A Repetitive Process, Patrick M. Sammons, Douglas A. Bristow, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition (LMD) is an additive manufacturing process whose dynamics are driven by complex heat transfer and fluid flow phenomena. The LMD process, along with every additive manufacturing process, is fundamentally a two-dimensional process possessing both temporal (or spatial) domain dynamics and propagation of information from layer to layer. However, modeling the two-dimensionality of the process for use in control has received little attention. Here, a model aimed at capturing the important nonlinear two-dimensional physical processes of the melt pool shape, while maintaining simplicity, is presented. The model is expressed in a form that lends itself to the design …
Control-Oriented Modeling For Open-Cathode Fuel Cell Systems,
2014
Missouri University of Science and Technology
Control-Oriented Modeling For Open-Cathode Fuel Cell Systems, Joseph Ishaku, Nima Lotfi, Hesam Zomorodi, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Due to numerous advantages of Polymer Electrolyte Fuel Cells (PEMFCs), they are becoming the mainstream fuel cell of choice for different applications. Open-cathode PEMFCs, in particular, are gaining increased popularity in low to medium power applications due to their simple structure and low parasitic losses. However, in order to achieve safe operation, increased durability and optimal performance, advanced control algorithms, which typically require control-oriented models, need to be implemented on open-cathode fuel cell systems. The open-cathode fuel cell system includes the fuel cell stack and all of the auxiliary components that are vital for its operation. In this paper, control-oriented …
Thermal-Electromagnetic Analysis Of Infrared Antennas,
2014
Missouri University of Science and Technology
Thermal-Electromagnetic Analysis Of Infrared Antennas, Edward C. Kinzel, Brian Slovick, James Ginn, Brian Lail, Glenn Boreman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Antenna-coupled Metal-Oxide-Metal (MOM) diodes have been demonstrated for sensing and proposed for energy harvesting at THz, infrared, and even visible frequencies. The design of the antenna allows engineering of the response of the device with respect to polarization, wavelength and angle of incidence. The classic understanding of the antenna coupled MOM diode is that the electric field generated by the antenna causes electrons to tunnel through the barrier oxide. This is supported by the fact that when the oxide separates metals with different work functions, a properly polarized field can produce an asymmetric tunnel current under zero bias. Losses in …
Verifiable Frequency-Limited Adaptive Control Performance Based On Linear Matrix Inequalities,
2014
Missouri University of Science and Technology
Verifiable Frequency-Limited Adaptive Control Performance Based On Linear Matrix Inequalities, Mario Luca Fravolini, Tansel Yucelen, Daniel Wagner, Ali Albattat, Paolo Valigi
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Adaptive controllers are often criticized for the lack of clear and easy verification procedures that relate design parameters to time domain performance especially during transients. For this reason, it is a challenge to rigorously certify existing adaptive control algorithms. To that end, we propose a validation framework where stability and performance requirements are formulated in terms of Linear Matrix Inequalities. This brings the advantage that adaptive controller design and verification can be analyzed and optimized via the solution of a convex optimization whose objective is to guarantee the evolution of the error components within an a-priori specified domain. This approach …
Thermomechanical Properties And Stress Analysis Of 3-D Textile Composites By Asymptotic Expansion Homogenization Method,
2014
Missouri University of Science and Technlogy
Thermomechanical Properties And Stress Analysis Of 3-D Textile Composites By Asymptotic Expansion Homogenization Method, Muhammad Ridlo Erdata Nasution, Naoyuki Watanabe, Atsushi Kondo, Arief Yudhanto
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper formulates asymptotic expansion homogenization method for the analysis of 3-D composites whereby thermomechanical effects are considered. The equivalent thermomechanical properties, viz. elastic constants and coefficient of thermal expansion, of 3-D orthogonal interlock composites are obtained based on a unit-cell derived from the optical microscopy observation. The Young's modulus and Poisson's ratio obtained from the analysis are compared with those obtained by experiments. The results show a good agreement especially for the Young's modulus. Localization analysis based on the present formulation is also presented to assess the stresses within the constituents of 3-D composites (fiber tows and resin region) …
Crystallization In Nano-Confinement Seeded By A Nanocrystal -- A Molecular Dynamics Study,
2014
Missouri University of Science and Technology
Crystallization In Nano-Confinement Seeded By A Nanocrystal -- A Molecular Dynamics Study, Heng Pan, Costas Grigoropoulos
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Seeded crystallization and solidification in nanoscale confinement volumes have become an important and complex topic. Due to the complexity and limitations in observing nanoscale crystallization, computer simulation can provide valuable details for supporting and interpreting experimental observations. In this article, seeded crystallization from nano-confined liquid, as represented by the crystallization of a suspended gold nano-droplet seeded by a pre-existing gold nanocrystal seed, was investigated using molecular dynamics simulations in canonical (NVT) ensemble. We found that the crystallization temperature depends on nano-confinement volume, crystal orientation, and seed size as explained by classical two-sphere model and Gibbs-Thomson effect.
Experimental Studies Of Lox/Ch4 Uni-Element Shear Coaxial Injector Geometry,
2014
University of Texas at El Paso
Experimental Studies Of Lox/Ch4 Uni-Element Shear Coaxial Injector Geometry, Vanessa Dorado-Martinez
Open Access Theses & Dissertations
The Center for Space Exploration Technology Research (cSETR) has developed a set of shear coaxial injectors as part of a system-level approach to study LOX/CH4 combustion. This Thesis describes the experimental studies involved in the characterization of the effects produced by two design injection face plate variables: post thickness and recession length. A testing program was developed to study the injectors' atomization process using LN2 as a substitute for LOX in cold flow and the flame anchoring mechanisms in hot firings. The cold flow testing stage was conducted to obtain liquid core measurements and compare its behavior between the different …
Importance Of Sources Using The Repeated Fusion Method And The Proportional Conflict Redistribution Rules #5 And #6,
2014
University of New Mexico
Importance Of Sources Using The Repeated Fusion Method And The Proportional Conflict Redistribution Rules #5 And #6, Florentin Smarandache, Jean Dezert
Branch Mathematics and Statistics Faculty and Staff Publications
We present in this paper some examples of how to compute by hand the PCR5 fusion rule for three sources, so the reader will better understand its mechanism. We also take into consideration the importance of sources, which is different from the classical discounting of sources.
Improving Scoliosis Rehabilitation,
2014
University of Texas at Arlington
Improving Scoliosis Rehabilitation, Ryan Neufeld
Mechanical and Aerospace Engineering Theses - Archive
Scoliosis, a disease that mainly affects children, is a deformity of the spinal column in all three dimensions. Treatment for scoliosis aims at straightening the spine with minimal discomfort to the patient. Current treatments involve wearing a polymeric brace that based on its design, exerts force on the spine in order to straighten it. The shape of the brace and the locations where the brace should apply forces are defined based on the experience of the orthotics specialist. Currently used braces are not equipped with sensors to monitor the loads generated and possibly aid in the rehabilitation process. The rehabilitation …
Computational Study Of Data Center Hotspot Mitigation With Snorkels As An Alternative Rack-Level Containment Strategy,
2014
University of Texas at Arlington
Computational Study Of Data Center Hotspot Mitigation With Snorkels As An Alternative Rack-Level Containment Strategy, Chris Onyiorah
Mechanical and Aerospace Engineering Theses - Archive
One of the major concerns of companies around the world is business continuity and with that comes the need to prevent operational dysfunction by keeping their information systems available and functional. IT professionals therefore, are constantly striving towards network sustainability by boosting the cooling cycle and infrastructure in data centers, while also reducing overall energy consumption. The combination of increasing IT workloads and packaging densities place stringent requirements on data center cooling systems and so, various traditional airflow management technologies have been implemented that propose significant energy savings and potential reduction in net annual cost for running data centers.In this …
