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- Type:
- Article
- Descripción/Resumen:
- The present study deals with an AFCA (Adaptive Fuzzy Control Algorithm) for an Euler-Bernoulli approximation of a two-dimensional version of a cantilever beam-like orthogonal tetrahedral space truss. Transient disturbances, modeled as a unit impulse, excite all the modes of the beam. The resulting transverse displacement at the free end of the beam and its corresponding rate are observed by sensors placed there, and active control of the beam is provided by a collocated force actuator. A design methodology for the closed-loop control algorithm that is independent of an exact mathematical model (space-state model, F.E.M., etc.) of plant dynamics and which is based on fuzzy logic is presented. First, the behavior of the open-loop system is observed. Then, the control force applied to the system emulates the behavior of a dynamic vibration absorber which is tuned to the measured fundamental frequency. This approach not only assures inherent stability associated with passive absorbers, but also circumvents the phenomenon of modal spillover. The damping and the mass ratios of the absorber adapt themselves by using a fuzzy decision-making process. This results in relatively quick settling times, low overshoots and dying out of vibration within a few seconds. When the control force is turned off after a mere 16 seconds, almost all the vibrational energy is dissipated. In addition, the performance of the AFCA is insensitive to varying initial conditions. To demonstrate the robustness of the control system to changes in the temporal dynamics of the cantilever beam, the transient response to a considerably perturbed plant is simulated. The Young's modulus of the beam was raised as well as lowered substantially, thereby significantly perturbing the natural frequencies of vibration. The mode shapes, however, remain unchanged. For these cases, too, the AFCA provides similar settling times and rates of vibrational energy dissipation.
- Creador/Autor:
- Abramovich, Haim; Weller, T.; Cohen, Kelly, and Levitas, Joseph
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 1997-03
- Licencia:
- All rights reserved
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- Type:
- Article
- Descripción/Resumen:
- The present study deals with an AFCA (Adaptive Fuzzy Control Algorithm) for an Euler-Bemoulli approximation of a two-dimensional version of a cantilever beam-like orthogonal tetrahedral space truss. Transient disturbances, modeled as a unit impulse, excite all the modes of the beam. The resulting transverse displacement at the free end of the beam and its corresponding rate are observed by sensors placed there, and active control of the beam is provided by a collocated force actuator. A design methodology, based on fuzzy logic which assumes no a priori knowledge of plant dynamics, for the closed-loop control algorithm results in relatively quick settling times, low overshoots and dying out of vibration within a few seconds. The control algorithm is enhanced and made much faster by eliminating the need of repeatedly solving the set of differential equations of motion of an emulated dynamic vibration absorber. When the control force is turned off after a mere 15 seconds, almost all the vibrational energy is dissipated as the beam returns to its undisturbed state throughout its length. In addition, the performance of the AFCA is insensitive to varying initial conditions. To examine the robustness of the control system to changes in the temporal dynamics of the cantilever beam, the transient disturbance response to a considerably perturbed plant is simulated. The Young's modulus of the beam was raised as well as lowered by 60%, substantially perturbing the natural frequencies of vibration compared to the nominal plant. The AFCA provided similar settling times and rates of vibrational energy dissipation, satisfying the aim of plant model independence.
- Creador/Autor:
- Abramovich, Haim; Weller, Tanchum; Cohen, Kelly, and Levitas, Joseph
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 1996-03
- Licencia:
- All rights reserved
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- Type:
- Article
- Descripción/Resumen:
- For a Timoshenko beam model the equations of motion, representing the anisotropic continuum model of a two-dimensional, latticed, large space structure, are extended to include coupling between the extensional, shear and bending modes. This analytical model, applied to a 20-bay, orthogonal, tetrahedral, cantilevered truss structure, is used to determine the transient response when subjected to a unit impulse. It is demonstrated that for beam-like structures having a fixed bending stiffness and beam mass an increase in diagonal stiffness, on account of the stiffness of the vertical girder, leads to a rise in the transverse shear rigidity. This results in higher natural frequencies and a reduction in peak displacement. In addition, in an asymmetrical truss configuration, coupling between the extensional and shear modes raises the maximum peak displacement compared to that obtained for a symmetric truss. The model is modified to investigate the introduction of passive damping in the form of several dynamic vibration absorbers. For a fixed absorber mass budget, a simple yet efficient absorber parameter optimization procedure, based on the classical steady state criteria of a 2-DOF system, is developed to design several absorbers each tuned to a different modal frequency. It is found that inclusion of transverse shear rigidity, as a design parameter in damping augmentation studies, reduces settling time for predetermined maximum peak displacements.
- Creador/Autor:
- Weller, T. and Cohen, Kelly
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 1994-08
- Licencia:
- All rights reserved
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- Type:
- Article
- Descripción/Resumen:
- Breakthroughs in genetic fuzzy systems, most notably the development of the Genetic Fuzzy Tree methodology, have allowed fuzzy logic based Artificial Intelligences to be developed that can be applied to incredibly complex problems. The ability to have extreme performance and computational efficiency as well as to be robust to uncertainties and randomness, adaptable to changing scenarios, verified and validated to follow safety specifications and operating doctrines via formal methods, and easily designed and implemented are just some of the strengths that this type of control brings. Within this white paper, the authors introduce ALPHA, an Artificial Intelligence that controls flights of Unmanned Combat Aerial Vehicles in aerial combat missions within an extreme-fidelity simulation environment. To this day, this represents the most complex application of a fuzzy-logic based Artificial Intelligence to an Unmanned Combat Aerial Vehicle control problem. While development is on-going, the version of ALPHA presented withinwas assessed by Colonel (retired)Gene Lee who described ALPHA as “the most aggressive, responsive, dynamic and credible AI (he’s) seen-to-date.” The quality of these preliminary results in a problem that is not only complex and rife with uncertainties but also contains an intelligent and unrestricted hostile force has significant implications for this type of Artificial Intelligence. This work adds immensely to the body of evidence that this methodology is an ideal solution to a very wide array of problems.
- Creador/Autor:
- Schumacher, Corey; Cohen, Kelly; Ernest, Nicholas; Carroll, David; Lee, Gene, and Clark, Matthew
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 2016-03
- Licencia:
- All rights reserved
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- Type:
- Article
- Descripción/Resumen:
- This work presents a methodology for real-time estimation of wildland fire growth, utilizing afire growth model based on a set of partial differential equations for prediction, and harnessing concepts of space-time Kalman filtering and Proper Orthogonal Decomposition techniques towards low dimensional estimation of potentially large spatio-temporal states. The estimation framework is discussed in its criticality towards potential applications such as forest fire surveillance with unmanned systems equipped with onboard sensor suites. The effectiveness of the estimation process is evaluated numerically over fire growth data simulated using a well-established fire growth model described by coupled partial differential equations. The methodology is shown to be fairly accurate in estimating spatio-temporal process states through noise-ridden measurements for real-time deploy ability.
- Creador/Autor:
- Sharma, Balaji R.; Cohen, Kelly, and Kumar, Manish
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 2013-10
- Licencia:
- All rights reserved
-
- Type:
- Article
- Descripción/Resumen:
- Not Available.
- Creador/Autor:
- Cancelas, Jose A. and Taniguchi, E.
- Peticionario:
- Jose Cancelas
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/10/2017
- Fecha de creacion:
- 2012-09-01
- Licencia:
- All rights reserved
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- Type:
- Article
- Descripción/Resumen:
- The methods and outcome of a senior undergraduate project related to the control of a turbulent cylinder wake flow using plasma actuators are summarized in this article. The study integrates computational fluid dynamics (CFD) with experimentation and combines fluid mechanics with flow control research, crossing the boundaries between engineering disciplines.Comput. Appl. Eng. Educ.
- Creador/Autor:
- Cohen, Kelly; McLaughlin, Thomas; Seaver, Christopher A., and Aradag, Selin
- Peticionario:
- Kelly Cohen
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/05/2017
- Fecha de creacion:
- 2009-02
- Licencia:
- All rights reserved
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Insertional Mutagenesis Identifies a STAT3/Arid1b/ b-catenin Pathway Driving Neurofibroma Initiation
- Type:
- Article
- Descripción/Resumen:
- Wu et al. map an Nf1-Stat3-Arid1b/ b-catenin pathway that initiates Neurofibromatosis type 1 (Nf1) neurofibromas, using unbiased insertional mutagenesis screening. Stat3 transcriptionally represses Gsk3b and Arid1b, thereby activating b-catenin in Schwann cell precursors and resulting in neurofibroma initiation and maintenance. Stat3-mediated modification plays a role in early tumorigenesis.
- Creador/Autor:
- Spinner, R. J.; Ratner, N.; Largaespada, D. A.; Keng, V.; Patmore, D. M.; Wu, J., and Cancelas, Jose A.
- Peticionario:
- Jose Cancelas
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/10/2017
- Fecha de creacion:
- 2016-02
- Licencia:
- All rights reserved
-
- Type:
- Article
- Descripción/Resumen:
- PM-18. EGFR-STAT3 ACTIVATES b-CATENIN SIGNALING TO DRIVE NEUROFIBROMA INITIATION IN NF1, AND PLAYS A ROLE IN TUMOR MAINTENANCE Nancy Ratner1, Vincent Keng2, Deanna M. Patmore1, Jed K. Kendall1, Edwin Jousma1, Kwangmin Choi1, Danhua Fan2, Eric B. Schwartz2, James R. Fuchs2, Yuanshu Zou2, Mi-Ok Kim1, Eva Dombi5, David E. Levy6, Jose A. Cancelas1, Anat Stemmer-Rachamimov4, Robert J. Spinner3, and David A. Largaespada2; 1 Cincinnati Children’s, Cincinnati, OH, USA; 2 University of Minnesota, Minneapolis, MN, USA; 3 Mayo Clinic, Rochester, MN, USA; 4 Massachusetts General Hospital, Boston, MA, USA; 5 National Cancer Institute Pediatric Branch, Bethesda, MD, USA; 6 New York University School of Medicine, New York, NY, USA To identify genes and signaling pathways that drive peripheral nerve tumor initiationand growth beyond the Ras-MAPK pathwaywe used unbiased insertional mutagenesis screening. We identified Stat3 as a potential driver of Neurofibromatosis type 1 neurofibroma. Targeted genetic deletion of Stat3 in Schwann cell precursors (SCPs) and Schwann cells (SCs) largely prevented neurofibroma formation, and self-renewal of tumor initiating cells. Genetic gain- and loss-of-function identified EGFR as the major upstream regulator of P-Stat3 in mouse and human neurofibroma SCP and in neurofibroma initiation; IL-6 reinforced EGFR/Jak/Stat signaling. Preclinical tests of a Jak2/ Stat3 inhibitor reduced established neurofibroma growth, supporting an additional role for Stat3 in benign nerve tumor maintenance. Unexpectedly, downstream of Stat3, we identified b-catenin, and b-catenin expression rescued phenotypic effects of Stat3 loss in SCPs. Phosphorylated STAT3 (Y705) and b-catenin were strongly correlated in NF1 human plexiform neurofibromas. The data support testing of JAK/STAT inhibition and Wnt/ b-catenin pathway inhibition in neurofibroma therapeutic trials. Supported by: NIH R01 NS28840 to N.R. and NIH P50 NS057531 to N.R. and D.L.), a DAMD New Investigator Award (W81XWH-11-1-0259) and an Ohio State University Comprehensive Cancer Center Pelotonia Idea Grant (to J.W.). The American Cancer Society (IRG-67-003-44) supported J.R.F.
- Creador/Autor:
- Schwartz, E. B.; Ratner, N.; Largaespada, D. A.; Cancelas, Jose A., and Stemmer-Rachamimov, A. O.
- Peticionario:
- Jose Cancelas
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/10/2017
- Fecha de creacion:
- 2014-11
- Licencia:
- All rights reserved
-
- Type:
- Article
- Descripción/Resumen:
- Overnight, room temperature hold (ONH) of whole blood before component processing offers several benefits. This study evaluated the storage and in vivo recovery characteristics of ONH red blood cells (RBCs) stored in additive solution-7 (AS-7).
- Creador/Autor:
- Szczerpiorkowski, Z. M.; Whitley, P.; Maes, L. A.; Dumont, L. J.; Cancelas, Jose A.; Zia, M.; Hess, J. R.; Rugg, N., and Herschel, L.
- Peticionario:
- Jose Cancelas
- Fecha modificada:
- 02/08/2017
- Fecha modificada:
- 04/10/2017
- Fecha de creacion:
- 2014-10
- Licencia:
- All rights reserved