Search results for "synchronization"

Evidence of unbalanced regulatory mechanism of heart rate and systolic pressure after acute myocardial infarction

2002

The interactions between systolic arterial pressure (SAP) and R-R interval (RR) fluctuations after acute myocardial infarction (AMI) were investigated by measures of synchronization separating the feedback from the feedforward control and capturing both linear and nonlinear contributions. The causal synchronization, evaluating the ability of RR to predict SAP (χs/t) or vice versa (χt/s), and the global synchronization (χ) were estimated at rest and after head-up tilt in 35 post-AMI patients, 20 young and 12 old. Significance and nonlinearity of the coupling were assessed by surrogate data analysis. Tilting increased the number of young subjects in which RR-SAP link was significant (from 17…

Sectoral Business Cycle Synchronization in the European Union

2007

This paper analyses sectoral business cycle synchronization in an enlarged European Union using annual data for the period 1980-2005. In particular, we try to identify which sector for each country is driving the aggregate output business cycle synchronization. Overall, the sectors that provide the most relevant contribution are Industry, Building and Construction, and Agriculture, Fishery and Forestry. In contrast, the Services sector, the largest one in terms of valued added share, shows a relative low business cycle synchronization and volatility, implying that it contributes only marginally to the aggregate output business cycle synchronization.

A synchronization property of pure subsemigroups of a free semigroup

1981

LTE-based passive radars and applications: a review

2021

This paper provides an overview of the most recent passive radars based on long-term evolution (LTE). To begin, this paper investigates the various characteristics and requirements of 4 G LTE signals for radar, taking performance aspects such as range, velocity, range resolution, and velocity resolution into account. An ambiguity function analysis is performed on a measured LTE signal using the synchronization and reference signal components to evaluate key performance parameters such as Doppler and range characteristics. We also discuss how LTE passive radar can be used in a variety of applications. The detailed analysis of the LTE downlink signal, its structural overview, and the effect o…

Generalized power-angle control for grid-forming converters: A structural analysis

2022

Several control schemes have been recently proposed and studied as grid-forming controls for power converters. In all these schemes, the power-angle control loop is the part which defines the fundamental capabilities of the grid-forming control: that control loop governs in fact the inherent synchronization mechanism of the power converter, the power sharing with the other generation sources in the system and the oscillatory characteristics of the converter-based resource. This article introduces a general formulation for the power-angle control characterizing the grid-forming concept for power converters. The generalized power-angle control is based on a polynomial fraction formulation, an…

Methodological advances in brain connectivity

2012

Determining how distinct neurons or brain regions are connected and communicate with each other is a crucial point in neuroscience, as it allows to investigate how the functional integration of specialized neural populations enables the emergence of coherent cognitive and behavioral states. The general concept of brain connectivity encompasses different aspects: structural connectivity is related to the description of anatomical pathways and synaptic connections; functional connectivity investigates statistical dependencies between spatially separated brain regions; effective connectivity refers to models aimed at elucidating driver-response relationships. The study of these different modes…

Estimation of Granger causality through Artificial Neural Networks: applications to physiological systems and chaotic electronic oscillators

2021

One of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Sq…

Efficient distributed average consensus in wireless sensor networks

2020

International audience; Computing the distributed average consensus in Wireless Sensor Networks (WSNs) is investigated in this article. This problem, which is both natural and important, plays a significant role in various application fields such as mobile agents and fleet vehicle coordination, network synchronization, distributed voting and decision, load balancing of divisible loads in distributed computing network systems, and so on. By and large, the average consensus' objective is to have all nodes in the network converged to the average value of the initial nodes' measurements based only on local nodes' information states. In this paper, we introduce a fully distributed algorithm to a…

Can Ventricular Resynchronization Reduce Atrial Fibrillation Recurrences?

2003

In recent years a new pacing therapy has been proposed for patients affected by heart failure (HF) in order to reduce inter- [1,2], intra- [3,4], and atrioventricular [5] (AV) dyssynchrony. Cardiac resynchronization therapy (CRT) has the goal of correcting these hemodynamic disorders, thus improving left ventricular (LV) performance. The benefits of CRT have been evaluated in a series of clinical trials [6-10].

Near field improvements of stochastic collaborative beamforming in wireless sensor networks

2020

Wireless sensor networks (WSN) are groups of small devices that contain a microcontroller in which a large number of sensors can be added. They transmit data and communicate to each other in the ISM band, standard IEEE 802.15.4, exchanging packets using a multi-hop routing. These devices are named motes and are nodes of the WSN. They are very simple and easy to program, powered by batteries of 1.5Volts (AA and AAA). The nodes are autonomous elements that can be deployed implementing any type of network. In a typical deployment the nodes communicate with each other and with a master node or Base Station (BS), which in turn transmits the information to an external server, which collects the e…