Higher Institute on Territorial Systems for Innovation
PORTO Publications Open Repository TOrinoNot a member yet
91193 research outputs found
Sort by
PRENOLIN: International Benchmark on 1D Nonlinear Site‐Response Analysis—Validation Phase Exercise
No full textThis article presents the main results of the validation phase of the PRENOLIN project. PRENOLIN is an international benchmark on 1D nonlinear (NL) site-response analysis. This project involved 19 teams with 23 different codes tested. It was divided into two phases; with the first phase verifying the numerical solution of these codes on idealized soil profiles using simple signals and real seismic records. The second phase described in this article referred to code validation for the analysis of real instrumented sites. This validation phase was performed on two sites (KSRH10 and Sendai) of the Japanese strong-motion networks KiK-net and Port and Airport Research Institute (PARI), respectively, with a pair of accelerometers at surface and depth. Extensive additional site characterizations were performed at both sites involving in situ and laboratory measurements of the soil properties. At each site, sets of input motions were selected to represent different peak ground acceleration (PGA) and frequency content. It was found that the code-to-code variability given by the standard deviation of the computed surface-response spectra is around 0.1 (in log10 scale) regardless of the site and input motions. This indicates a quite large influence of the numerical methods on site-effect assessment and more generally on seismic hazard. Besides, it was observed that sitespecific measurements are of primary importance for defining the input data in siteresponse analysis. The NL parameters obtained from the laboratory measurements should be compared with curves coming from the literature. Finally, the lessons learned from this exercise are synthesized, resulting also in a few recommendations for future benchmarking studies, and the use of 1D NL, total stress site-response analysis
Design and modeling of a space docking mechanism for cooperative on-orbit servicing
No full textThis dissertation addresses the design procedure of a docking mechanism for space applications, in particular, on-orbit servicing of cooperative satellites. The mechanism was conceived to comply with the technical specifications of the STRONG mission. The objective of this mission is to deploy satellite platforms using a space tug with electric propulsion. This mission is part of the SAPERE project, which focuses on space exploration and access to space. A docking mechanism is used for recovering the misalignments left by the guidance, navigation, and control system of the servicer satellite when approaching the customer spacecraft. However, most importantly, the mechanism must safely dissipate the energy associated with the relative velocities between the spacecraft upon contact. Five concepts were considered as possible candidates for the docking mechanism: a system based on the Stewart-Gough platform with a position controller, a Stewart-Gough platform with impedance control, a central passive mechanism (probe-drogue), a central active mechanism, and a mechanism equipped with articulated arms. Several trade-off criteria were defined and applied to the concepts. The result of this trade study was the selection of the central passive mechanism as the most balanced solution. This mechanism is composed of a probe and a conical frustum equipped with a socket to capture the probe. It was further developed and tested using mathematical models of the docking maneuver. The results of the simulations showed that the passiveness of the system prevented the docking maneuver from being fully accomplished. Consequently, a second design iteration was performed. In this new iteration, the degrees of freedom of the mechanism were increased by adding two controlled linear axes in series with the degrees of freedom of the preliminary design. The electromechanical actuators and transmissions of this mechanism were selected following the guidelines of The ECSS standards. Also, in this case, numerical models were used to assess the functioning of the docking system. The results produced by these models demonstrated the suitability of the mechanism for completing the docking operation defined by the mission's specifications. Furthermore, the results also showed the architecture and functioning of the mechanism to be possibly suitable for other cooperative docking operations between small and mid-sized satellites. In addition, the definition of the mechanical details as well as the control architecture led to the complete design of an engineering prototype for laboratory tests. In this regard, the laboratory tests were defined with the scope of verifying the different operating modes of the docking mechanism. The test rig was designed to be equipped with a serial manipulator connected to the female part of the mechanism through a force and torque module. The objective will be to simulate the relative motion between the docking halves using different techniques to generate the trajectory of the manipulator
CaO-Al 2 O 3 glass-ceramic as a joining material for SiC based components: A microstructural study of the effect of Si-ion irradiation
No full textPerformance indicators and automatic identification systems in inland freight terminals for intermodal transport
No full textMuscle activation patterns during gait: A hierarchical clustering analysis
No full textHuman gait is characterized by a large stride-to-stride variability of the muscle activation patterns (onset-offset timings). For this reason prolonged walking sessions lasting several minutes are analyzed. To interpret correctly the electromyographic (EMG) data collected during gait, it is important to group strides sharing similar EMG activation patterns. The aim of this work is to present and validate a method, based on hierarchical clustering, able to group strides showing homogeneous onset-offset activation intervals. Results show that the variability of the onset-offset timing is significantly reduced after clustering, for all of the five lower limb muscles considered to test this method. A by-product of the clustering procedure is the possibility to define and extract the principal activations of a muscle during gait. We define principal activations those activations that are necessary for the specific muscle contribution to the biomechanical function of walking. This concept may be useful whenever the dynamic performance of the muscle has to be compared in subsequent times, such as in patient's follow-up or when the performance of a specific subject is to be compared to that of a group of selected subjects. The contribution presented in this work could be beneficial in implementing a personalized medicine approach to rehabilitation. Clinical gait analysis, enriched by hierarchical clustering of EMG patterns as well as by the quantitative assessment of muscles principal activations, could greatly contribute to the design of therapeutic treatments tailored on the patient's needs
Analysis of laminated composites and sandwich structures by variable-kinematic MITC9 plate elements
No full textSome thermodynamic considerations on low frequency electromagnetic waves effects on cancer invasion and metastasis
No full textCell membranes are the reason of the cell energy transfer. In cells energy transfer, thermo-electro-chemical processes and transports phenomena occur through their membranes. Cells can actively modify their behaviours in relation to any change of their environment. They waste heat into their environment. The analysis of irreversibility related to this wasted heat, to the ions transport and the related cell-environment pH changes represents a new useful approach to the study of the cells behaviour. This analysis allows also the explanation of the effects of electromagnetic fields on the cell behaviour, and to suggest how low intensity electromagnetic fields could represent a useful support to the present anticancer therapies
Using Virtual Sensors in Industrial Manipulators for Service Algorithms Like Payload Checking
No full textIndustrial manipulators are usually equipped with a set of basic sensors (encoders and current sensors) that could not be sufficient to implement more advanced service and control algorithms, like the Payload Check, the Impedance Control or the Cartesian Soft Servo. A software layer between the real sensors and the algorithms is developed in order to provide a new set of "measures". Such a layer, called Virtual Sensor, exploits the information provided by the real sensors to compute new virtual measures, to be used in the algorithms layer to implement new services. The Virtual Sensor is introduced in a standard COMAU controller and its effectiveness is tested in a service algorithm, called Payload Check, able to detect a wrong declaration of the robot payload. Good performances have been obtained for a wide range of COMAUmanipulators
Application of a non-noble Fe-N-C catalyst for oxygen reduction reaction in an alkaline direct ethanol fuel cell
No full textA Fe-N-C non-noble metal (NNM) catalyst for oxygen reduction reaction (ORR) catalyst was prepared via hard templating method using Fe(II)-phthalocyanine. Its electrochemical behavior towards the ORR was tested in alkaline conditions using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. The kinetics of the reduction of the adsorbed oxygen, the selectivity, and the activity towards hydrogen peroxide reduction reaction (HPRR), were investigated. The ethanol tolerance and the stability in alkaline conditions were also assessed with the purpose to verify the good potentiality of this catalyst to be used in an alkaline direct ethanol fuel cell (DEFC). The results evidence that the ORR occurs mainly following the direct 4 e- reduction to OH-, and that the Fe-N-C catalysts is highly ethanol tolerant with a promising stability. The alkaline DEFC tests, performed after the optimization of the ionomer amount used for the preparation of the catalyst ink, show good results at low-intermediate currents, with a maximum power density of 62 mW cm-2. The initial DEFC performance can be partially recovered after a purge-drying procedure