State Space Models in R

We give an overview of some of the software tools available in R, either as built- in functions or contributed packages, for the analysis of state space models. Several illustrative examples are included, covering constant and time-varying models for both univariate and multivariate time series. Maximum likelihood and Bayesian methods to obtain parameter estimates are considered.

Vanadium redox flow batteries: Potentials and challenges of an emerging storage technology

open4noIn this paper an overview of Vanadium Redox Flow Battery technologies, architectures, applications and power electronic interfaces is given. These systems show promising features for energy storage in smart grid applications, where the intermittent power produced by renewable sources must meet strict load requests and economical opportunities. This paper reviews the vanadium-based technology for redox flow batteries and highlights its strengths and weaknesses, outlining the research lines that aim at taking it to full commercial success.openSpagnuolo, Giovanni, Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni;Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni; Spagnuolo, Giovann

Distributed Maximum Power Point Tracking: Challenges and Commercial Solutions

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A Closed-Form Filter for Binary Time Series

Non-Gaussian state-space models arise in several applications. Within this framework, the binary time series setting is a source of constant interest due to its relevance in many studies. However, unlike Gaussian state-space models, where filtering, predictive and smoothing distributions are available in closed-form, binary state-space models require approximations or sequential Monte Carlo strategies for inference and prediction. This is due to the apparent absence of conjugacy between the Gaussian states and the likelihood induced by the observation equation for the binary data. In this article we prove that the filtering, predictive and smoothing distributions in dynamic probit models with Gaussian state variables are, in fact, available and belong to a class of unified skew-normals (SUN) whose parameters can be updated recursively in time via analytical expressions. Also the functionals of these distributions depend on known functions, but their calculation requires intractable numerical integration. Leveraging the SUN properties, we address this point via new Monte Carlo methods based on independent and identically distributed samples from the smoothing distribution, which can naturally be adapted to the filtering and predictive case, thereby improving state-of-the-art approximate or sequential Monte Carlo inference in small-to-moderate dimensional studies. A scalable and optimal particle filter which exploits the SUN properties is also developed to deal with online inference in high dimensions. Performance gains over competitors are outlined in a real-data financial application

A PSO-based Global MPPT technique for Distributed PV Power Generation

International audienc

Instrumentation of sprint and long jump tracks of an indoor athletics field to study athletes’ performances

Introduction: The in-depth study of the performances of athletes is crucial to evaluate and improve their technique. However, collecting representative data is not trivial, as several factors could affect the measurements. Laboratory measurements can lack in realism (artificial environment, athlete’s lack of challenge), whereas data collected in-field using on-board devices can be influenced by the instrumentation itself (weight, encumbrance) [1-2]. The aim of this work is the design of an instrumented track, which will allow to collect kinematic and kinetic data of able bodied and paralimpic athletes in their natural environment, ensuring that the influence of the sensory apparatus is negligible. Methods: The instrumentation set-up of the indoor athletics track of Padova (Padova, 35136, Italy) is represented in the plan view of figure 1a. Seven 60x90 cm and two 40x60 cm force platforms (AMTI, BMS600900 and BMS400600) will be installed following the disposition depicted in figure 1b on the eighth lane of the sprint track, leading to a total of 6.9 metres of force sensing lane. The two smaller force platforms will be installed side-by-side to allow the possibility of mounting one single starting block on each force transducer to collect separate right and left ground reaction forces during the starting phase of sprinting. An additional 60x90 cm force platform will be installed on the long jump track at 1.6 metres from the sand pit in order to collect the last step of the athlete before the flight phase of the long jump (figure 1c). Kinematic data will be collected using 10 optoelectronic motion capture cameras (Vicon, Vantage5), which will be installed on a double portal structure made of aluminium trusses with an overall size of 13 x 7 x 3.5 metres (length x width x height). The structure size allows more than one athlete to run simultanesously, in order to recreate the “challenge effect” typical of official races. Compared to other motion capture mounting solutions, such as using tripods to support each individual camera [3], the use of this single support structure offers the advantage of allowing to rigidly translate the motion capture calibrated volume in different part of the athletics field using wheels. This feature reduces drastically the set-up time of the motion capture system, particularly when the data collection focus has to be moved between the sprint and the long jump area. Moreover, this structure allows to avoid the presence of any cable on the track, as wires will pass through the trusses and descend via the vertical columns. Results and discussion: The design of the sensorized athletics track is complete and the installation of the instrumentation will take place in the next few months. This track will allow to collect insightfull in-field data regarding able bodied and paralimpic athletes performances outside the laboratory environment. Examples of these data will be presented in June at the ISEA 2022 conference

STIFFNESS COMPARISON OF RUNNING PROSTHETIC FEET OF DIFFERENT CATEGORIES AFTER BENCH TESTING

The purpose of the work is the comparison of stiffness properties of Running Prosthetic Feet (RPF) for transtibial amputee athletes after the introduction of test methods to collect and analyse their Load-deflection curves. The study explores the effect of the orientation of the socket (ϑG) with respect to ground during a load cycle.The three Ossur feet Cheetah Xtreme Category 4th, 5th ,6th underwent extensive testing on a multi-component test bench. Results show that the unit interval between categories does not matches with the interval in terms of equivalent stiffness Keq introduced as synthetic stiffness parameter

Analysis of the degradation of amorphous silicon-based modules after 11 years of exposure by means of IEC60891:2021 procedure 3

The degradation of two amorphous silicon-based photovoltaic (PV) modules, namely, of single junction amorphous silicon (a-Si) and of micromorph tandem (a-Si/μ-Si), after 11 years of exposure in the south of Spain is analyzed. Their I-V curves were measured outdoors to study the changes of the electrical parameters in the course of three different periods: during the initial days of exposure, during the first year, and in the subsequent 10-year period. The translation of the curves to an identical set of operating conditions, which enables a meaningful comparison, was done by the dif ferent correction procedures described in the standard IEC60891:2021, including the procedure 3, which does not require the knowledge of module parameters, whose values are typically not available. The annual power degradation rates over the entire 11-year period are 1.12% for the a-Si module, which is 3.02% for the first year, and 0.98% for the a-Si/μ-Si, which is 2.29% for the initial yearThis work is supported by Ministero dell'Istruzione, dell'Università e della Ricerca (Italy) (grant PRIN2020-HOTSPHOT 2020LB9TBC and grant PRIN2017-HEROGRIDS 2017WA5ZT3_003); Università degli Studi di Salerno (FARB funds); Ministerio de Ciencia, Innovacion y Universidades (Spain) (grant RTI2018-095097-B-I0)

GRF ANALYSIS OF TWO ELITE PARALYMPIC SPRINTERS IN STEADY AND RESISTED ACCELERATED TREADMILL RUNNING

Analysis of ground reaction forces (GRFs) allows evaluating performances of paralympic runners with transfemoral amputation. Instrumented treadmills are expensive and low-cost solutions to gather GRFs are worth to be studied. This study aimed to use a commercial treadmill placed on four force platforms to evaluate vertical impulse, braking and propulsive horizontal impulses during steady-speed (SSR) and resisted accelerated (RAR) running. The RAR vertical impulses of the unaffected limb (UL) of the two athletes doubled the values of the affected limb (AL) that has, however, on average 23% larger propulsive action than UL in SSR. The horizontal impulse of AL remains positive in the first 10 steps during RAR, as expected. Agreement between present results and literature confirms that the proposed setup gives sufficient confidence in the evaluation of the sprint technique