Università degli Studi eCampus

About: Università degli Studi eCampus is a education organization based out in Novedrate, Italy. It is known for research contribution in the topics: Anxiety & Planck. The organization has 124 authors who have published 538 publications receiving 21483 citations. The organization is also known as: Universita degli Studi eCampus.

Experimental analysis of a fractional-order control applied to a second order linear system

Abstract: This paper presents the application of a PDD1/2 fractional order controller to a purely inertial second order system, with the aim of deepening the study of the half-derivative contribution on control performances, in particular on settling time and settling energy of a step response. An approximation of the half-derivative term is proposed for a discrete time version of the controller. The choice is justified by the results obtained by an analysis of order and sampling time influence on accuracy and computation time of a discrete-time fractional derivative. Afterwards, simulation results, all obtained in dimensionless form, are extended to the physical case by means of experimental tests on a rotary axis. In the end it is shown that the half-derivative approximation still allows to improve the system dynamics if compared with a conventional PD controller.

On the creep performance of the Ti-6Al-4V alloy processed by Additive Manufacturing

Abstract: The creep response of a Ti-6Al-4V alloy produced by additive manufacturing was investigated at 500, 600, and 650 °C using constant load experiments. A collection of recent data from the literature on Ti-6Al-4V produced by conventional technologies and heat treated to produce different microstructures was analysed to determine the effect of the microstructure on the creep behaviour of this material. A unique constitutive equation derived from a model developed for face-centred cubic (fcc) metals was successfully used to describe the creep response, irrespective of the different microstructures. The same constitutive model was able to provide an excellent description of the minimum creep rate dependence on the applied stress for the alloy produced by additive manufacturing, notwithstanding the obvious differences in the microstructures. These observations led to the reconsideration of some consolidated opinions on the behaviour of Ti-6Al-4V, shedding light on the substantial similarities in the creep responses when the microstructure has different morphologies. The initial microstructural features, which have traditionally been thought to greatly influence the creep response, indeed played an important role because they determined the magnitude of the ultimate tensile strength, but this effect gradually disappeared at high temperatures and low stresses.

Validity and reliability of the GYKO inertial sensor system for the assessment of the elbow range of motion.

Abstract: BACKGROUND The evaluation of joints range of motion (ROM) represents a fundamental step in the diagnosis of joint disorders. Assessors usually measure the ROM angle through a universal goniometer (UG). GYKO inertial system (Microgate, Bolzano, Italy) represent a noninvasive, easy-to-use, Inertial Measurement Unit (IMU) method for the measurement of the elbow ROM. The aim of this study was to validate the GYKO digital device comparing it with the gold standard UG in the measurement of elbow flexion-extension ROM in healthy subjects. METHODS Thirty healthy subjects (15 females, 15 males; mean age: 34 years, range 25-58 years) were enrolled. The elbow ROM of the dominant arm was measured with two methods, UG and GYKO. Active flexion-extension movement of the elbow was measured by two operators with UG (A1_UG; A2_UG) and with GYKO (A1_GYKO; A2_GYKO; B_GYKO). Intra-rater reliability, inter-rater reliability, and concurrent validity were analyzed by intraclass correlation coefficient (ICC) values. Bland-Altman plot was used to compare UG and GYKO. RESULTS Both methods were very reliable (P<0.001). Intra-rater reliability showed strong correlation respectively for the UG (ICC=0.798) and for GYKO (ICC=0.859) while inter-rater reliability showed moderate correlation with UG (ICC=0.726) and strong correlation with GYKO (ICC=0.942). The concurrent validity, obtained by three comparisons (A1, A2 and B) showed moderate correlation (ICC: 0.576-0.776). CONCLUSIONS The results of this study support the use of GYKO as useful as the UG for the assessment of the active flexion-extension ROM of the elbow.

Characterization of a mini-channel heat exchanger for a heat pump system

Abstract: In this paper a mini-channel aluminum heat exchanger used in a reversible heat pump is presented. Mini-channel finned heat exchangers are getting more and more interest for refrigeration systems, especially when compactness and low refrigerant charge are desired. Purpose of this paper was to characterize the mini-channel heat exchanger used as evaporator in terms of heat transfer performance and to study the refrigerant distribution in the manifold. The heat exchanger characterization was performed experimentally by means of a test rig built up for this purpose. It is composed of an air-to-air heat pump, air channels for the external and internal air circulation arranged in a closed loop, measurement sensors and an acquisition system. The overall heat transfer capacity was assessed. Moreover, in order to characterize the flow field of the refrigerant in the manifold of the heat exchanger, a numerical investigation of the fluid flow by means of CFD was performed. It was meant to evaluate the goodness of the present design and to identify possible solutions for the future improvement of the manifold design.

Hot Recycling of Reclaimed Asphalt Using a Bio-based Additive

Abstract: Hot recycling of reclaimed asphalt (RA) has increasing interest worldwide due to economical and environmental benefits. In particular, the use of RA in place of virgin aggregates reduces of aggregate supply and disposal of RA. Moreover, the hot recycling process allows reusing the aged bitumen from the RA, implying a reduction of the required amount of new bitumen. However, the ageing process, which occurs from the production throughout the service life of the pavement, affects physical and chemical properties of bitumen, determining its hardening. For this reason, when high amounts of RA has to be reused (more than 20 % by aggregate weight), the use of specific additives is strongly recommended in order to reach the desired bitumen properties and consequently to produce an asphalt concrete (AC) with high performance. This experimental project focused on the use of a bio-based additive (A) for the production of an AC for binder course with a high amount of RA. The experimental program consisted of two main phases: the first phase dealt with the mix design of three mixtures containing respectively no RA, 40 % of RA, 40 % of RA treated with A; the second phase aimed at producing and laying down in a trial section selected mixtures for the validation of the full-scale hot recycling process.