Skeleton-based human action and gesture recognition for human-robot collaboration

openThe continuous development of robotic and sensing technologies has led in recent years to an increased interest in human-robot collaborative systems, in which humans and robots perform tasks in shared spaces and interact with close and direct contacts. In these scenarios, it is fundamental for the robot to be aware of the behaviour that a person in its proximity has, to ensure their safety and anticipate their actions in performing a shared and collaborative task. To this end, human activity recognition (HAR) techniques have been often applied in human-robot collaboration (HRC) settings. The works in this field usually focus on case-specific applications. Instead, in this thesis we propose a general framework for human action and gesture recognition in a HRC scenario. In particular, a transfer learning enabled skeleton-based approach that employs as backbone the Shift-GCN architecture is used to classify general actions related to HRC scenarios. Pose-based body and hands features are exploited to recognise actions in a way that is independent from the environment in which these are performed and from the tools and objects involved in their execution. The fusion of small network modules, each dedicated to the recognition of either the body or hands movements, is then explored. This allows to better understand the importance of different body parts in the recognition of the actions as well as to improve the classification outcomes. For our experiments, we used the large-scale NTU RGB+D dataset to pre-train the networks. Moreover, a new HAR dataset, named IAS-Lab Collaborative HAR dataset, was collected, containing general actions and gestures related to HRC contexts. On this dataset, our approach reaches a 76.54% accuracy

A Practical Tool to Generate Complex Energy System Configuration Based on the SYNTHSEP Methodology

Traditional fossil fueledpower plants are commonly based on steam Rankine cycle or Brayton Joule cycle. Using water or air as working fluid is obviously the most obvious choice for the wide availability of these substances in nature. However, the scarcity of natural energy sources and the strong need of reducing environmental impact have necessarily drawn the research to new energy systems configurations operating with other working fluids, which are able to recover lower temperature sources, such as Sun or industrial wasted heat. The variety of new working fluids (refrigerants or organic fluids) widens the choice to a variety of configurations that can be tailored to the specific source characteristics and boundary constraints. It is not always easy or even possible to conceive the best configuration for given specifications withthe mere experience of a common designer. To design a new system configuration, the designer normally uses some \u201cnon-codified rules\u201d deriving from his knowledge of basic thermodynamics and energy engineering. This paper aims instead at showing a practicaltool that is based on a new methodology, named SYNTHSEP, to generate new energy system configurations. This methodology starts from the simple thermodynamic cycles operated by a given fluid made up of the four fundamental processes (compression, heating, expansion and cooling) and uses a rigorous set of codified rules to build the final system configuration. The paper presents the basics of the new methodology and how it has been implemented in a practical tool that simply requires the information about the elementary cycles and their shared processes as input data

The Karyology of Tisbe Reluctans (Copepoda, Harpacticoida)

SUMMARYThe diploid chromosome number, 2 n = 24, has been established, in both sexes of the harpacticoid copepod Tisbe reluctans. The chromosomes are metacentric or submetacentric and differentiated sex chromosomes are not present. In the male chiasmatic bivalents form at metaphase I. In the female, during the first meiotic division and before the diffuse stage, homologous chromosomes are closely associated so that chiasmata may occur. After the diffuse stage, the homologues separate but remain parallel and juxtaposed to each other till metaphase I. The chromosomes seem to have doubled into two chromatids during the post-diffuse stage

Techno-economic analysis of expander-based configurations for natural gas liquefaction

The use of liquefied natural gas (LNG) as a marine fuel is rapidly growing because of the possible economic advantages over conventional fuels and stricter environmental regulations. Production of LNG is energy intensive because of the required temperature level of around -160\ub0C. Three main types of refrigeration cycles have been developed. The present work focuses on the comparison of six expander-based configurations, which in spite of the higher power consumption, are more compact, flexible and easier to operate. They are optimised from a thermodynamic perspective: the exergetic efficiency is found to range between 17 % and 33 % for a specific power consumption down to 1340 kJ/kg. Multi-objective optimisations are performed to simultaneously minimise the net power consumption and the heat transfer conductance as an indicator of the required heat transfer area. The latter ranges between 50 kW/K and 300 kW/K. A trade-off between power consumption and heat transfer area is found, which justifies a further economic analysis. A simplified economic analysis is set based on a discounted cash flow model. The unitary profit ranges between 0.5 and 0.9 DKK/kg of produced LNG. The most profitable expander-based configuration is the dual-refrigerant cycle with nitrogen in the bottoming refrigeration cycle. Finally, the influence of the cost correlations on the economic outcome is assessed: the compressors represent the major costs, which leads to the coincidence of the thermodynamic and economic optima

Neutrophil extracellular traps : function in infectious and non-Infectious conditions

Neutrophil extracellular traps (NETs) are composed of a backbone of chromatin, decorated with microbicidal peptides and proteolytic enzymes, and are used by neutrophils as a weapon against pathogens. Since their initial discovery in 2004, NETs have challenged scientists in terms of the nature of the triggers and the mechanisms of neutrophil release of NETs, as well as the implication of these extracellular structures in infectious and non-infectious human diseases. The work presented in this thesis, performed in an interdisciplinary perspective using an array of different methodologies, aims to deepen the knowledge on the functionality and dysfunctionality of NETs, including the mechanism of NET disposal and its immunological consequences. Once NETs have fulfilled their anti-microbial function, the timely clearance of these structures is needed in order to avoid a misguided autoinflammatory response. In Paper I, we showed that primary human macrophages employ TREX1, while dendritic cells use DNase1L3 to digest NETs purified from activated neutrophils. In addition, on the basis of cytokine profiling, we showed that NETs have immunomodulatory effects on phagocytes. In Paper II, we showed that JAGN1 is required for efficient fungal killing in NETs. Patients suffering from severe congenital neutropenia (SCN) present homozygous mutations in the gene encoding JAGN1 and are susceptible to bacterial and fungal infections. We found that JAGN1-deficient neutrophils isolated from an SCN patient, as well as neutrophil-like HL-60 cells with silenced JAGN1 expression, released NETs, but the expression of myeloperoxidase (MPO) was altered. In Paper III and IV we explored the interactions of NETs with graphene oxide (GO), a carbon-based 2-D material. Using ToF-SIMS, a mass spectrometry-based surface analytical method, we could show in Paper III that GO interacts with the plasma membrane of neutrophils, promoting cholesterol oxidation. In addition, we could define a size-dependent mechanism of GO induced release of NETs. Furthermore, we showed in Paper IV that GO undergoes efficient extracellular degradation through neutrophil degranulation or in NETs in a process dependent on MPO. Moreover, intermediate degradation products of GO did not cause DNA damage in lung cells. Overall, the work presented in this thesis has shed light on the clearance and degradation of NETs by phagocytic cells and the involvement of several endonucleases in a cell type-specific manner, and has confirmed the importance of NETs in fungal killing, with new evidence for a role of JAGN1 in this process. In addition, we have shown for the first time that GO triggers NETs and reported that GO may also undergo degradation in NETs in a similar manner as pathogens. Our studies have thus revealed that MPO expressed in NETs is a key element in eliminating infectious as well as non-infectious agents

Optimum design and performance of a solar dish microturbine using tailored component characteristics

Versión revisada. Embargo 24 mesesThe aim of the paper is to find the optimum design and performance of solar microturbines powered by parabolic dish collectors using an innovative methodology which integrates the design and off-design models of the total system. In contrast to the common practice of assigning an estimated efficiency to the engine turbomachinery (generalized performance maps), the procedure hereinafter produces the specific geometry and the characteristic maps of compressor and turbine, according to their inlet/outlet thermodynamic states and working cycle boundary conditions. With this global approach, a sensitivity analysis is performed to search for the pressure ratio that maximizes the solar-to-electric efficiency at design point for a constant air mass flow rate and turbine inlet temperature. Maximum values in the range 18.0–21.7% are obtained for a pressure ratio of 3.2 when the turbine inlet temperature changes between 800 °C (base-case system) and 900 °C. The methodology allows also to simulate the performance of the system when different design DNIs are considered with the aim to maximize the annual yield of the system. Simulations performed for Beijing, Seville and San Diego showed that quite different DNIs (610–815 W/m2) are to be chosen to get the maximum annual (average) efficiency: 11–16% for the base-case system and 14–19% for a more advanced design.Comisión Europea Grant Agreement No. 30895

Research of efficiency of the organic Rankine cycle on a mathematical model

The object of the study are the organic Rankine cycle. The purpose of research is to evaluate the impact on the net efficiency of the initial and final properties of the cycle at work on a saturated and superheated steam. Investigations were carried out on the basis of a mathematical model, in which the thermodynamic properties of materials are determined on the basis of "REFPROP". On the basis of the available scientific publications on the use of working fluids in an organic Rankine cycle analysis was selected ozone-safe pentane. A mathematical model has been developed on condition that condenser is used as air cooler which allows the substance to condense at a temperature below 0 С. Numerical study on the mathematical model shown that net efficiency at work on pentane linearly depends on the condensation temperature and parabolically depends on the initial temperature with the saturated steam. During work at the superheated steam efficiency strongly depends on both the initial temperature and of the initial pressure. With rising initial temperature is necessary to gradually increase the initial pressure under certain conditions

Experimental performance evaluation of a multi-diaphragm pump of a micro-ORC system

Abstract The performance of micro-scale ORC systems strongly depends on the performance of their key components. While the heat exchangers and expander have been extensively investigated, the pump has only received limited attention. The main purpose of this work is the experimental characterization of a multi-diaphragm positive displacement pump, integrated in an experimental ORC system with a rated power output of 4kWel. The study focuses on the experimental evaluation of the pump performance and on cavitation phenomena. A detailed presentation of the experimental procedure and results is supplied. A great effort has been spent in calculating the global and volumetric pump efficiencies for a wide range of operational conditions, which reach maximum values around 45-48% and 95%, respectively. With regards to cavitation issues, the effect of the available Net Positive Suction Head at the pump inlet has been deeply investigated both at partial and full load to obtain guidelines for stable operation. Finally, an extensive dataset of steady-state operating points has been used to calibrate an improved version of a semi-empirical model previously developed for positive displacement ORC pumps. Special attention has been given to the ability of the model to accurately predict the behaviour and performance of the pump at different, properly chosen, steady-state conditions. Relative errors in between 0.5%, for the outlet temperature, and 10%, for the electric power consumption, are achieved

Riduzione delle perdite al camino e delle emissioni nocive grazie ai nuovi bruciatori recuperativi a canali suddivisi e rigenerativi

La riduzione delle perdite di calore al camino, spesso, rappresentala via più efficace e conveniente peraumentare il rendimento dei forni industriali. I bruciatoririgenerativi offrono un rendimento termico superiore,a fronte di una spesa maggiore in termini di cicli di accensionee di aspirazione dei fumi; i nuovi bruciatori conrecuperatore di calore integrato a canali suddivisi offrono in un sistema recuperativo lo stesso rendimentotermico dei bruciatori rigenerativi. Entrambi i modelli di bruciatore utilizzano la tecnologia della combustionesenza fiamma per la riduzione delle emissioni di NOx