Search results for "95"

COVID-19 Drives Consumer Behaviour and Agro-Food Markets towards Healthier and More Sustainable Patterns

2020

This study examines the extant state of research into our understanding of the impact of the coronavirus pandemic in its early stages on food-purchasing behaviour. As such, it includes a summary and categorisation of the findings, extending to consumption preferences worldwide. After the indiscriminate stockpiling of food, which was witnessed in many countries following the implementation of the lockdown, the impact of COVID-19 (COronaVIrus Disease-2019) on consumer habits has inversely varied in function of personal attitudes, individual and household experiences, and characteristics. Specific contexts, and the financial, economic, and logistic nature of these contexts, have also been foun…

Elementi di Contabilità Nazionale

2009

mplicit Identification of Contact Parameters in a Continuous Chain Model

2011

Accurate contact modeling is of great importance in the field of dynamic chain simulations. In this paper emphasis is on contact dynamics for a time-domain simulation model of large chains guided in a closed loop track. The chain model is based on theory for unconstrained rigid multibody dynamics where contact within the chain and with the track is defined through continuous point contacts using the contact indentation and rate as means. This paper presents an implicit method to determine contact parameters of the chain model through the use of none gradient optimization methods. The set of model parameters are estimated by minimizing the residual between simulated and measured results. The…

Discrete Learning Control with Application to Hydraulic Actuators

2015

In this paper the robustness of a class of learning control algorithms to state disturbances, output noise, and errors in initial conditions is studied. We present a simple learning algorithm and exhibit, via a concise proof, bounds on the asymptotic trajectory errors for the learned input and the corresponding state and output trajectories. Furthermore, these bounds are continuous functions of the bounds on the initial condition errors, state disturbance, and output noise, and the bounds are zero in the absence of these disturbances.

Computing Euclidean Steiner trees over segments

2020

In the classical Euclidean Steiner minimum tree (SMT) problem, we are given a set of points in the Euclidean plane and we are supposed to find the minimum length tree that connects all these points, allowing the addition of arbitrary additional points. We investigate the variant of the problem where the input is a set of line segments. We allow these segments to have length 0, i.e., they are points and hence we generalize the classical problem. Furthermore, they are allowed to intersect such that we can model polygonal input. As in the GeoSteiner approach of Juhl et al. (Math Program Comput 10(2):487–532, 2018) for the classical case, we use a two-phase approach where we construct a superse…

Experimental System Identification and Black Box Modeling of Hydraulic Directional Control Valve

2015

Directional control valves play a large role in most hydraulic systems. When modeling the hydraulic systems, it is important that both the steady state and dynamic characteristics of the valves are modeled correctly to reproduce the dynamic characteristics of the entire system. In this paper, a proportional valve (Brevini HPV 41) is investigated to identify its dynamic and steady state characteristics. The steady state characteristics are identified by experimental flow curves. The dynamics are determined through frequency response analysis and identified using several transfer functions. The paper also presents a simulation model of the valve describing both steady state and dynamic charac…

Analysis of Offshore Knuckle Boom Crane - Part Two: Motion Control

2013

In this paper design of electro-hydraulic motion control systems for offshore knuckle boom cranes is discussed. The influence of the control valve bandwidth along with the ramp time for the control signal are investigated both analytically with simplified system models and numerically with an experimentally verified crane model. The results of both types of investigations are related to general design rules for selection of control valves and ramp times and the relevance of these design rules is discussed. Generally, they are useful but may be too conservative for offshore knuckle boom cranes. However, as demonstrated in the paper, the only proper way to determine this is to evaluate the mo…

Hacia la convergencia de las estadísticas de las finanzas públicas y la contabilidad pública en Europa a nivel central y local

2018

[EN] The main aim of this paper is to study the convergence between micro and macro systems of government accounting information, looking to contribute to the analysis of accounting harmonization process in the EU, as a tool to improve the comparability of financial, budgetary, and aggregated statistical reports, in order to improve social, political and economic decision-making and accountability. All this is obviously located in the current context of the EU, with a high degree of harmonization of accounting standards between the International Public Sector Accounting Standards (IPSAS), and those applied for the preparation of national accounts, ruled by European System of National and Re…

A Playful Experiential Learning System With Educational Robotics

2020

This article reports on two studies that aimed to evaluate the effective impact of educational robotics in learning concepts related to Physics and Geography. The reported studies involved two courses from an upper secondary school and two courses from a lower secondary school. Upper secondary school classes studied topics of motion physics, and lower secondary school classes explored issues related to geography. In each grade, there was an “experimental group” that carried out their study using robotics and cooperative learning and a “control group” that studied the same concepts without robots. Students in both classes were subjected to tests before and after the robotics laboratory, to c…

Direct Instruction vs. Cooperative Learning in Physical Education: Effects on Student Learning, Behaviors, and Subjective Experience

2020

(1) Background: The objective was to analyze if cooperative learning (CL) can have benefits compared to direct instruction (DI) in learning, behavior, and subjective experience of pupils. (2) Methods: An intervention was performed with a counterbalanced within-subjects design. To perform the intervention, 75 schoolchildren aged 10 to 12 from four primary classes were divided into two groups, and two units were taught in each one, namely &ldquo