Design of experiments for nonlinear system identification: A set membership approach

Design of Experiments (DoE) is an important step in system identification. Regardless of the chosen model structure and identification method, the DoE quality determines an upper bound on the accuracy of the identified models. One of the greatest challenges in this context is to design an experiment which gives the maximum information about the dynamics of the system of interest. In this paper, a novel DoE algorithm for input-constrained MISO nonlinear systems, based on set membership identification, is proposed. The DoE algorithm is aimed to minimize the so-called radius of information, a quantity giving the worst-case model error. Two numerical examples are presented, showing the effectiveness of the approach and its potential in view of real-world applications

Effect of processing conditions on the thermal and electrical conductivity of poly (butylene terephthalate) nanocomposites prepared via ring-opening polymerization

Successful preparation of polymer nanocomposites, exploiting graphene-related materials, via melt mixing technology requires precise design, optimization and control of processing. In the present work, the effect of different processing parameters during the preparation of poly (butylene terephthalate) nanocomposites, through ring-opening polymerization of cyclic butylene terephthalate in presence of graphite nanoplatelets (GNP), was thoroughly addressed. Processing temperature (240{\deg}C or 260{\deg}C), extrusion time (5 or 10 minutes) and shear rate (50 or 100 rpm) were varied by means of a full factorial design of experiment approach, leading to the preparation of polybutylene terephthalate/GNP nanocomposite in 8 different processing conditions. Morphology and quality of GNP were investigated by means of electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry and Raman spectroscopy. Molecular weight of the polymer matrix in nanocomposites and nanoflake dispersion were experimentally determined as a function of the different processing conditions. The effect of transformation parameters on electrical and thermal properties was studied by means of electrical and thermal conductivity measurement. Heat and charge transport performance evidenced a clear correlation with the dispersion and fragmentation of the GNP nanoflakes; in particular, gentle processing conditions (low shear rate, short mixing time) turned out to be the most favourable condition to obtain high conductivity values

Orchidaceae

Hierbas epífitas o terrestres, autótrofas o saprófitas, arbustos o bejucos (Fuera de Salta), con raíces engrosadas, generalmente carnosas por la presencia de un tejido hidrorreservante llamado “velamen”. Tallos cortos o alargados, frecuentemente engrosados en pseudobulbos. Hojas simples, solitarias, apareadas o numerosas, con lámina entera, membranácea o carnosa, venación mayormente paralelicurvada; a veces reducidas a escamas, raro ausentes. Inflorescencias terminales o laterales polimorfas, desde panojas muy copiosas o racimos espiciformes multifloros, hasta reducida a una sola flor. Flores muy variables, desde diminutas hasta grandes y vistosas, cíclicas, perfectas, raro imperfectas, zigomorfas. Perianto petaloide, formado por 2 verticilos trímeros, donde el externo posee los sépalos y pueden diferenciarse por su forma y tamaño en un sépalo mediano o superior y 2 laterales. Verticilo interno con 3 pétalos, el inferior más desarrollado llamado “labelo”, con superficie a veces ornamentada de diversas maneras: con pelos, callos, papilas o estrías; con o sin una giba o un espolón que, en casos extremos, llega a medir hasta 50 cm de long. Androceo soldado con el gineceo formando el ginostemio. Estambres y estilo reunidos en un solo órgano floral la columna, que soporta 1 ó 2 anteras en su ápice o costados. Estambres 3, de los cuales 2 generalmente abortan o se transforman en estaminodios y solo uno es funcional, conteniendo 1 ó 2 anteras fértiles. De los 3 estigmas generalmente 2 son receptivos, el tercero suele transformarse en un órgano estéril especializado el rostelo, que lleva las anteras. Polen reunido en polinias, formadas por 2 másulas de granos polínicos reunidas entre sí a través de 2 caudículas conectadas a un retináculo. Ovario ínfero, 3- carpelar, recto o resupinado, con torsión longitudinal de 180º; placentación parietal. Óvulos numerosísimos, hasta más de 3 millones por fruto en casos extremos, muy diminutos a su madurez. Fruto cápsula 3-carpelar, 1-3-locular, placentación generalmente axilar. Semillas, muy diminutas, exalbuminadas, desde ovoides a elipsoides hasta alargadas, casi filiformes, aplanadas y aladas. Cubierta finamente escobiforme, sin tegumentos. Embrión indiferenciado, rudimentario, reducido a una masa de células que se reconocen por su menor tamaño

Subspace Identification of a Glucose-Insulin model Using Meal Tracer Protocol Measurements

In this study, the problem of identifying a low complexity state space model describing glucose and insulin dynamics from low sample meal tracer experiments is investigated. Triple tracer meal protocol measurements (sampled as low as 15 samples per meal) together with continuous glucose monitoring measurements, measured concurrently at a rate of 5 minutes per sample, are used. A new formulation to estimate the missing input and output measurements at such low sample rates is developed. Nuclear norm minimization is used to exploit low rankness of the stacked input and output matrix, while the {ell1} norm is used to exploit an available sparse basis for the glucose flux profiles. Simulation results, using the UVa Padova simulator, show that the technique outperforms previous methods and also demonstrate the possibility of identifying state space models from triple tracer measurements with good prediction performance under non-ideal conditions

Control design for UAV quadrotors via embedded model control

In this paper, a control system for unmanned aerial vehicles (UAVs) is designed, tested in simulation by means of a high-fidelity simulator, and then applied to a real quadrotor UAV. A novel approach is proposed for the control design, based on the combination of two methodologies: feedback linearization (FL) and embedded model control (EMC). FL allows us to properly transform the UAV dynamics into a form suitable for EMC; EMC is then used to control the transformed system. A key feature of EMC is that it encompasses a so-called extended state observer (ESO), which not only recovers the system state but also gives a real-time estimate of all the disturbances/uncertainties affecting the system. This estimate is used by the FL-EMC control law to reject the aforementioned disturbances/uncertainties, including those collected via the FL, allowing a robustness and performance enhancement. This approach allows us to combine FL and EMC strengths. Most notably, the entire process is made systematic and application oriented. To set-up a reliable UAV attitude observer, an effective attitude sensors fusion is proposed and also benchmarked with an enhanced complementary filter. Finally, to enhance the closed-loop performance, a complete tuning procedure, encompassing frequency requirements, is outlined, based on suitably defined stability and performance metrics

Approaches to Daily Monitoring of the SARS-CoV-2 Outbreak in Northern Italy

Italy was the first European country affected by the Sars-Cov-2 pandemic, with the first autochthonous case identified on Feb 21st. Specific control measures restricting social contacts were introduced by the Italian government starting from the beginning of March. In the current study we analyzed public data from the four most affected Italian regions. We (i) estimated the time-varying reproduction number (Rt), the average number of secondary cases that each infected individual would infect at time t, to monitor the positive impact of restriction measures; (ii) applied the generalized logistic and the modified Richards models to describe the epidemic pattern and obtain short-term forecasts. We observed a monotonic decrease of Rt over time in all regions, and the peak of incident cases ~2 weeks after the implementation of the first strict containment measures. Our results show that phenomenological approaches may be useful to monitor the epidemic growth in its initial phases and suggest that costly and disruptive public health controls might have had a positive impact in limiting the Sars-Cov-2 spread in Northern Italy

Steering Behavior of an Articulated Amphibious All-Terrain Tracked Vehicle

This paper presents a study related to an Articulated Amphibious All-Terrain Tracked Vehicle (ATV) characterized by a modular architecture. The ATV is composed by two modules: The first one hosts mainly the vehicle engine and powertrain components, meanwhile the second one can be used for goods transportation, personnel carrier, crane and so on. The engine torque is transmitted to the front axle sprocket wheel of each module and finally distributed on the ground through a track mechanism. The two modules are connected through a multiaxial joint designed to guarantee four relative degrees of freedom. To steer the ATV, an Electro Hydraulic Power System (EHPS) is adopted, thus letting the vehicle steerable on any kind of terrain without a differential tracks speed. The paper aims to analyze the steady-state lateral behavior of the ATV on a flat road, through a non-linear mathematical vehicle model built in Matlab/Simulink environment. The model describes the vehicle main planar motion and the interaction between the two modules through the application of a hydraulic steering torque. The model simulates steady-state handling maneuvers in Matlab/Simulink. Two scenarios are considered: One with the application of an open-loop hydraulic steering torque without any vehicle feedback; the second one with a closed-loop steering torque actuation based on the relative angle between the two modules (hitch angle). Finally, the influence of the ATV longitudinal speed on vehicle lateral characteristics is also presented

New trends in teacher\u2019s education. Educational placement of the adopted child

In Italy, the number of adopted school-age children is increasing. According to the Commission of Intercountry Adoption (2013), 3106 children were adopted, 47.5% of them are between 5 and 9 years old. The present action-research aims at exploring the spread of good approaches in schools in terms of welcoming of adopted children. For this purpose, 268 teachers of primary schools were involved in analyzing the social representation about adopted children and their family. The results show a simplified vision of the adoptive family, which is described as heroic family or, on the contrary, as a family with difficulty