316 research outputs found
Inflation Dynamics’ Micro Foundations: How Important is Imperfect Competition Really?
This paper analyzes price formation and dynamics according to the industry structure. It divides manufacturing industries of Mexico into two groups: perfectly and imperfectly competitive. The results show that imperfectly competitive industries predominate. Then this classification is used to build consumer price sub indexes for the goods of both sectors. These sub indexes’ inflation dynamics indicate that the exchange rate pass-through in the perfectly competitive sector is significantly higher than in the imperfectly competitive sector, while wage pass-through only affects the imperfectly competitive sector. Also, that inflation inertia is lower in the former than in the latter; adding up in more volatility of the perfectly competitive inflation rate. For policy makers an interesting feature of the perfectly competitive price index is that the evidence suggests that its variations precede those of the imperfectly competitive price index. For economic theorists these features validate recent macroeconomic models with heterogeneous price setting behaviorPanzar-Rosse, Industry Structure, Inflation, Price Dynamics, Price Indexes
Embedded Object Detection and Mapping in Soft Materials Using Optical Tactile Sensing
In this paper, we present a methodology that uses an optical tactile sensor
for efficient tactile exploration of embedded objects within soft materials.
The methodology consists of an exploration phase, where a probabilistic
estimate of the location of the embedded objects is built using a Bayesian
approach. The exploration phase is then followed by a mapping phase which
exploits the probabilistic map to reconstruct the underlying topography of the
workspace by sampling in more detail regions where there is expected to be
embedded objects. To demonstrate the effectiveness of the method, we tested our
approach on an experimental setup that consists of a series of quartz beads
located underneath a polyethylene foam that prevents direct observation of the
configuration and requires the use of tactile exploration to recover the
location of the beads. We show the performance of our methodology using ten
different configurations of the beads where the proposed approach is able to
approximate the underlying configuration. We benchmark our results against a
random sampling policy
Event-triggered attitude control for flying robots using an event approach based on the control
International audienceThis paper presents the development of a quaternion-based nonlinear event-triggered control for the attitude stabilization of Flying robots. Firstly, it is proved the existence of a Control Lyapunov Function. Unlike some previously proposed schemes, the aim of this paper is to propose a new and simpler event function. The control law ensures the asymptotic stability of the closed-loop system to the desired attitude. The approach is validated in real-time using a quadrotor mini-helicopter. The experiments show that the event driven controller reduces the control update without deteriorating the closed-loop system performance
Event-triggered attitude control for flying robots using an event approach based on the control
International audienceThis paper presents the development of a quaternion-based nonlinear event-triggered control for the attitude stabilization of Flying robots. Firstly, it is proved the existence of a Control Lyapunov Function. Unlike some previously proposed schemes, the aim of this paper is to propose a new and simpler event function. The control law ensures the asymptotic stability of the closed-loop system to the desired attitude. The approach is validated in real-time using a quadrotor mini-helicopter. The experiments show that the event driven controller reduces the control update without deteriorating the closed-loop system performance
A survey on active simultaneous localization and mapping: state of the art and new frontiers
Active simultaneous localization and mapping (SLAM) is the problem of planning and controlling the motion of a robot to build the most accurate and complete model of the surrounding environment. Since the first foundational work in active perception appeared, more than three decades ago, this field has received increasing attention across different scientific communities. This has brought about many different approaches and formulations, and makes a review of the current trends necessary and extremely valuable for both new and experienced researchers. In this article, we survey the state of the art in active SLAM and take an in-depth look at the open challenges that still require attention to meet the needs of modern applications. After providing a historical perspective, we present a unified problem formulation and review the well-established modular solution scheme, which decouples the problem into three stages that identify, select, and execute potential navigation actions. We then analyze alternative approaches, including belief-space planning and deep reinforcement learning techniques, and review related work on multirobot coordination. This article concludes with a discussion of new research directions, addressing reproducible research, active spatial perception, and practical applications, among other topics
Event-based control strategy for consensus of a group of VTOL-UAVs
International audienceThis paper presents the development of a collaborative event-based control applied to the problem of consensus and formation of a group of VTOL-UAVs (Vertical Takeoff and Landing, Unmanned Aerial Vehicles). Each VTOL-UAV decides, based on the difference of its current state (linear position and velocity) and its latest broadcast state, when it has to send a new value to its neighbors. The asymptotic convergence to average consensus or desired formation is depicted via numerical simulations
Evaluación de fallas en un transportador de cangilones. Caso de estudio
A failure in the bottom sheet of a bucket conveyor (KZBQ.AUMUND)
during service was investigated. Sheets are
coupled to the chain throught a screw connection; they
operate in variable load scenarios causing fatigue. A
chemical and microstructural analysis was made showing
that sheet was built in steel with 0.15 % of Carbone without
alloying elements that contribute to the refined grain and
resistance increase. Strength calculation, used to
determinate safety factor, consider load system and type
material. Results concluded that geometry and thickness
value do not provide an adequate fatigue resistance
coefficient.Es investigada la falla en las láminas del fondo de un
transportador de cangilones KZB-Q.AUMUND durante su
servicio. Las láminas están acopladas a una cadena a través
de uniones atornilladas y operan bajo un régimen de cargas
variables causándoles fatiga. Se realiza un análisis químico y
microestructural el cual evidencia que las láminas fueron
elaboradas de un acero con 0,15 % de carbono sin
elementos de aleación que contribuyan al afinamiento del
grano y al incremento de la resistencia. Se calculan las
tensiones para determinar el coeficiente de seguridad a la
fatiga considerando el sistema de cargas y el material de las
láminas. Los resultados concluyen que la geometría y los
valores de espesor no le proporcionan a las láminas un
adecuado coeficiente de resistencia a la fatiga
Room Temperature Exciton-Polariton Condensation in Silicon Metasurfaces Emerging from Bound States in the Continuum
We show the first experimental demonstration of room-temperature
exciton-polariton (EP) condensation from a bound state in the continuum (BIC).
This demonstration is achieved by strongly coupling stable excitons in an
organic perylene dye with the extremely long-lived BIC in a dielectric
metasurface of silicon nanoparticles. The long lifetime of the BIC, mainly due
to the suppression of radiation leakage, allows for EP thermalization to the
ground state before decaying. This property results in a condensation threshold
of less than 5 \mu J cm^{-2}, one order of magnitude lower that the lasing
threshold reported in similar systems in the weak coupling limit
Nonlinear control of a nano-hexacopter carrying a manipulator arm
International audienceThis paper proposes a simple solution for stabilization of a nano-hexacopter carrying a manipulator arm in order to increase the type of missions achievable by these types of systems. The manipulator arm is attached to the lower part of the hexacopter. The motion of the arm induces a change of the center of mass of the whole body, which induces torques which can produce the loss of stability. The present work deals with the stabilization of the whole system-that is hexacopter and arm-by means of a set of nonlinear control laws. First, an attitude control, stabilizes the hexacopter to a desired attitude taking into account the movement of the arm. Then, a suitable virtual control and the translational dynamics allow the formulation of a nonlinear controller, which drives the aerial vehicle to a desired position. Both controls consist in saturation functions. Experimental results validate the proposed control strategy and compares the results when the motion of the arm is taken into account or not
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