Root-Locus Analysis of Delayed First and Second Order Systems

For finite dimensional linear system the root-locus method is well established however for the case of delayed systems the method has some problems due to the transcendental term involved. This work intends to illustrate the problems that arises when a root-locus diagram is performed as well as to develop a Matlab function that provides the root-locus diagram for delayed low order systems. In this way, some comments about the problems that should be tackled to obtain a generalization of the computational method for delayed systems with real m poles and n zero

Synthesis of Ternary Borocarbonitrides by High Temperature Pyrolysis of Ethane 1,2-Diamineborane

Ethane 1,2-diamineborane (EDAB) is an alkyl-containing amine-borane adduct with improved hydrogen desorption properties as compared to ammonia borane. In this work, it is reported the high temperature thermolytic decomposition of EDAB. Thermolysis of EDAB has been investigated by concomitant thermogravimetry-differential thermal analysis-mass spectrometry experiments. EDAB shows up to four H2 desorption events below 1000 °C. Small fractions of CH4, C2H4 and CO/CO2 are also observed at moderate-high temperatures. The solid-state thermolysis product has been characterized by means of different structural and chemical methods, such as X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, Elemental analysis, and X-ray photoelectron spectroscopy (XPS). The obtained results indicate the formation of a ternary borocarbonitride compound with a poorly-crystalline graphitic-like structure. By contrast, XPS measurements show that the surface is rich in carbon and nitrogen oxides, which is quite different to the bulk of the materialSome authors (Fabrice Leardini, Lorenzo Massimi, Maria Grazia Betti and Carlo Mariani) also thank Sapienza Università di Roma for financial support under “Progetti di Ateneo”, and the Italian Ministry of Education and Research (MIUR) for the PRIN grant “GRAF” n. 20105ZZTS

CP--violating Chargino Contributions to the Higgs Coupling to Photon Pairs in the Decoupling Regime of Higgs Sector

In most supersymmetric theories, charginos $\tilde{\chi}^\pm_{1,2}$ belong to the class of the lightest supersymmetric particles and the couplings of Higgs bosons to charginos are in general complex so that the CP--violating chargino contributions to the loop--induced coupling of the lightest Higgs boson to photon pairs can be sizable even in the decoupling limit of large pseudoscalar mass $m_A$ with only the lightest Higgs boson kinematically accessible at future high energy colliders. We introduce a specific benchmark scenario of CP violation consistent with the electric dipole moment constraints and with a commonly accepted baryogenesis mechanism in the minimal supersymmetric Standard Model. Based on the benchmark scenario of CP violation, we demonstrate that the fusion of the lightest Higgs boson in linearly polarized photon--photon collisions can allow us to confirm the existence of the CP--violating chargino contributions {\it even in the decoupling regime of the Higgs sector} for nearly degenerate SU(2) gaugino and higgsino mass parameters of about the electroweak scale.Comment: 1+13 pages, 3 eps figure

Lubricated revolute joints in rigid multibody systems

The main purpose of this work is to present a general methodology for modeling lubricated revolute joints in constrained rigid multibody systems. In the dynamic analysis of journal-bearings, the hydrodynamic forces, which include both squeeze and wedge effects, generated by the lubricant fluid, oppose the journal motion. The hydrodynamic forces are obtained by integrating the pressure distribution evaluated with the aid of Reynolds’ equation, written for the dynamic regime. The hydrodynamic forces built up by the lubricant fluid are evaluated from the system state variables and included into the equations of motion of the multibody system. Numerical examples are presented in order to demonstrate the use of the methodologies and procedures described in this work.Fundação para a Ciência e a Tecnologia (FCT

Jacobi-Lie systems: Fundamentals and low-dimensional classification

A Lie system is a system of differential equations describing the integral curves of a $t$-dependent vector field taking values in a finite-dimensional real Lie algebra of vector fields, a Vessiot-Guldberg Lie algebra. We define and analyze Lie systems possessing a Vessiot-Guldberg Lie algebra of Hamiltonian vector fields relative to a Jacobi manifold, the hereafter called Jacobi-Lie systems. We classify Jacobi-Lie systems on $\mathbb{R}$ and $\mathbb{R}^2$. Our results shall be illustrated through examples of physical and mathematical interest.Comment: 15 pages. Examples, references and comments added. Based on the contribution presented at "The 10th AIMS Conference on Dynamical Systems, Differential Equations and Applications", July 07-11, 2014, Madrid, Spain. To appear in the Proceedings of the 10th AIMS Conferenc

Evolution of Phenolic Content, Antioxidant Capacity and Phenolic Profile during Cold Pre-fermentative Maceration and Subsequent Fermentation of Cabernet Sauvignon Red Wine

The phenolic compound profile and content of red wines are modified during the maceration-fermentation process by several factors that alter the extractability of the compounds and by reactions that phenolic compounds undergo, and can be directly related to the quality of the final wine and its beneficial effects on the consumer. The aim of this study was to determine the change in phenolic content and profile during cold pre-fermentative maceration and fermentation without the removal of grape pomace. Total phenolics,flavonoids, anthocyanins, tannins and antioxidant capacity were determined by spectrophotometric methods, and the phenolic profile was determined by HPLC-MS on each day of the maceration-fermentation process. The results showed a variation in the content of phenolic compounds and antioxidant activity over time, but the final phenolic content showed no significative difference compared with the initial content (1 268 mg GAE/L and 1 115 mg GAE/L respectively). The phenolic profile showed that flavonoids were theprincipal compounds in wine and that they increased at the end of the winemaking. Condensed tannins also increased during fermentation, while anthocyanins and some phenolic acids decreased at the end of the process. The final content of phenolic compounds was similar to the initial one, but there was a change in the different fractions of phenolic compounds at the end of fermentation

Decentralized event-based leader-following consensus for a group of two-wheeled self-balancing robots

[EN] This paper deals with the development of a decentralized event-based control strategy applied to the leader-following consensus problem of a group of two-wheeled self-balancing robots so called mobile inverted pendulum (MIP). The MIP’s nonlinear mathematical model which includes the dynamics of the actuators is presented. Then, the model around an operating point is considered which allows to exploit the differential flatness property of the system, permitting a complete parametrization in terms of the flat output. Assuming that the vehicle network exchange information through a directed and strongly connected graph, a decentralized control law is designed, and an event-based algorithm is developed. Then each MIP decides, based on the difference of its current state and its latest broadcast state, when it has to send a new value to its neighbors. The stability of the complete system is carried out in the Lyapunov sense together with the ISS (Input-to-State Stability) approach. Numerical results show the advantages \textit{wrt} information exchange between MIPs, as well as a good performance in the angular stabilization under two scenarios: regulation and tracking problem.[ES] El trabajo presenta el diseno de una estrategia de control distribuido con comunicación activada por eventos, que resuelve el problema de consenso líder-seguidor, de un conjunto de robots móviles tipo péndulo invertido (RMPI). La linealización de las ecuaciones de movimiento de los RMPI, alrededor del punto de equilibrio, permiten explotar las propiedades de planitud diferencial, dando lugar a una reparametrización del sistema mediante la salida plana. Asumiendo que los vehículos se comunican mediante una red, cuya topología es representada por un grafo no dirigido y fuertemente conectado, se disena una ley de control distribuido y una funcion de evento que indica el instante en el que el i-ésimo vehículo debe transmitir informacion (su estado) a sus vecinos. El resultado es un intercambio asíncrono de información entre vehículos y donde el tiempo entre eventos no es equidistante. El análisis de estabilidad se lleva a cabo en el sentido de Lyapunov y en el sentido entrada-estado ISS (Input-to-State Stability). Los resultados en simulación numérica muestran el buen desempeño del consenso de la red de vehículos en dos escenarios representativos: regulación y seguimiento de trayectoria.Ramírez-Cárdenas, O.; Guerrero-Castellanos, J.; Linares-Flores, J.; Durand, S.; Guerrero-Sánchez, W. (2019). Control descentralizado basado en eventos para el consenso de múltiples robots tipo péndulo invertido en el esquema líder-seguidor. Revista Iberoamericana de Automática e Informática. 16(4):435-446. https://doi.org/10.4995/riai.2019.11113SWORD435446164Ahmed, N., Cortes, J., Martinez, S., 2016a. Distributed control and estimation of robotic vehicle networks: Overview of the special issue. 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Sliding mode control of two-wheeled welding mobile robot for tracking smooth curved welding path. KSME International Journal 18 (7), 1094-1106. https://doi.org/10.1007/BF02983284Dimarogonas, D. V., Frazzoli, E., Johansson, K. H., 2012. Distributed eventtriggered control for multi-agent systems. IEEE Transactions on Automatic Control 57 (5), 1291-1297. https://doi.org/10.1109/TAC.2011.2174666Durand, S., Marchand, N., Aug 2009. Further results on event-based pid controller. In: Control Conference (ECC), 2009 European. pp. 1979-1984. https://doi.org/10.23919/ECC.2009.7074694Frías, O. O. G., 2013. Estabilización del péndulo invertido sobre dos ruedas mediante el método de lyapunov. Revista Iberoamericana de Automática e Informática Industrial RIAI 10 (1), 30 - 36. https://doi.org/10.1016/j.riai.2012.11.003Garcia, E., Cao, Y., Wang, X., Casbeer, D. W., July 2015. Decentralized eventtriggered consensus of linear multi-agent systems under directed graphs. In: 2015 American Control Conference (ACC). pp. 5764-5769. https://doi.org/10.1109/ACC.2015.7172242Ge, X., Han, Q. L., 2017. Distributed formation control of networked multiagent systems using a dynamic event-triggered communication mechanism. IEEE Transactions on Industrial Electronics PP (99), 1-1.Grasser, F., D'Arrigo, A., Colombi, S., Rufer, A. C., Feb 2002. Joe: a mobile, inverted pendulum. IEEE Transactions on Industrial Electronics 49 (1), 107-114. https://doi.org/10.1109/41.982254Guerrero Castellanos, J. F., Vega-Alonzo, A., Marchand, N., Durand, S., Linares-Flores, J., Mino-Aguilar, G., 2017. Real-time event-based formation control of a group of vtol-uavs. In: Proceedings of the 3rd IEEE International Conference on Event-Based Control, Communication and Signal Processing (EBCCSP). Hal-01527633. https://doi.org/10.1109/EBCCSP.2017.8022817Guinaldo, M., Fábregas, E., Farias, G., Dormido-Canto, S., Chaos, D., Sánchez, J., Dormido, S., 2013. A mobile robots experimental environment with event-based wireless communication. Sensors 13 (7), 9396-9413. https://doi.org/10.3390/s130709396Hebertt Sira-Ramírez, Alberto Luviano-Juárez, M. R.-N. E.-W. Z.-B., 2017. Active Disturbance Rejection Control of Dynamic Systems. Butterworth- Heinemann.Lewis, F. L., Zhang, H., Hengster-Movric, K., Das, A., 2013. Cooperative control of multi-agent systems: optimal and adaptive design approaches. Springer Science & Business Media. https://doi.org/10.1007/978-1-4471-5574-4Li, Z., Yang, C., Fan, L., 2003. Advanced Control of Wheeled Inverted Pendulum Systems. Springer-Verlag London.Marchand, N., Durand, S., Guerrero-Castellanos, J. F., 2013. A general formula for event-based stabilization of nonlinear systems. Automatic Control, IEEE Transactions on 58 (5), 1332-1337. https://doi.org/10.1109/TAC.2012.2225493Müllhaupt, P., 2009. Introduction à l'analyse et à la commande des systèmes non linéaires. 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Recoil Order Chiral Corrections to Baryon Octet Axial Currents and Large NcN_c QCD

We compute the chiral corrections to octet baryon axial currents through ${\cal O}(p^3)$ in heavy baryon chiral perturbation theory, including both octet and decuplet baryon intermediate states. We include the latter in a consistent way by using the small scale expansion. We find that, in contrast to the situation at ${\cal O}(p^2)$, there exist no cancellations between octet and decuplet contributions at ${\cal O}(p^3)$. Consequently, the ${\cal O}(p^3)$ corrections spoil the expected scaling behavior of the chiral expansion. We discuss this result in terms of the $1/N_c$ expansion. We also consider the implications for determination of the strange quark contribution to the nucleon spin from polarized deep inelastic scattering data.Comment: 7 page