Modeling and Model Predictive Control of an Industrial Hydraulic System

This thesis aims to illustrate the construction of a mathematical model of a hydraulic system, oriented to the design of a model predictive control (MPC) algorithm. The modeling procedure starts with the basic formulation of a piston-servovalve system. The latter is a complex non linear system with some unknown and not measurable effects that constitute a challenging problem for the modeling procedure. The first level of approximation for system parameters is obtained basing on datasheet informations, provided workbench tests and other data from the company. Then, to validate and refine the model, open-loop simulations have been made for data matching with the characteristics obtained from real acquisitions. The final developed set of ODEs captures all the main peculiarities of the system despite some characteristics due to highly varying and unknown hydraulic effects, like the unmodeled resistive elements of the pipes. After an accurate analysis, since the model presents many internal complexities, a simplified version is presented. The latter is used to linearize and discretize correctly the non linear model. Basing on that, a MPC algorithm for reference tracking with linear constraints is implemented. The results obtained show the potential of MPC in this kind of industrial applications, thus a high quality tracking performances while satisfying state and input constraints. The increased robustness and flexibility are evident with respect to the standard control techniques, such as PID controllers, adopted for these systems. The simulations for model validation and the controlled system have been carried out in a Python code environment.

Modeling, characterization and microalgal cultivation in an airlift panel photobioreactors.

Microalgae cultures are attracting great attentions in many industrial applications. However, one of the technical challenges is to cut down the capital and operational costs of microalgae production systems, with special difficulty in reactor design and scale-up. The thesis work open with an overview on the microalgae cultures as a possible answer to solve some of the upcoming planet issues and their applications in several fields. After the work offers a general outline on the state of the art of microalgae culture systems, taking a special look to the enclosed photobioreactors (PBRs). The overall objective of this study is to advance the knowledge of PBRs design and lead to innovative large scale processes of microalgae cultivation. An airlift flat panel photobioreactor was designed, modeled and experimentally characterized. The gas holdup, liquid flow velocity and oxygen mass transfer of the reactor were experimentally determined and mathematically modeled, and the performance of the reactor was tested by cultivation of microalgae. The model predicted data correlated well with experimental data, and the high concentration of suspension cell culture could be achieved with controlled conditions. The reactor was inoculated with the algal strain Scenedesmus obliquus sp. first and with Chlorella sp. later and sparged with air. The reactor was operated in batch mode and daily monitored for pH, temperature, and biomass concentration and activity. The productivity of the novel device was determined, suggesting the proposed design can be effectively and economically used in carbon dioxide mitigation technologies and in the production of algal biomass for biofuel and other bioproducts. Those research results favored the possibility of scaling the reactor up into industrial scales based on the models employed, and the potential advantages and disadvantages were discussed for this novel industrial design.

Numerical and experimental investigation of turbulent dissipation

Turbulent energy dissipation is presented in the theoretical context of the famous Kolmogorov theory, formulated in 1941. Some remarks and comments about this theory help the reader understand the approach to turbulence study, as well as give some basic insights to the problem. A clear distinction is made amongst dissipation, pseudo-dissipation and dissipation surrogates. Dissipation regulates how turbulent kinetic energy in a flow gets transformed into internal energy, which makes this quantity a fundamental characteristic to investigate in order to enhance our understanding of turbulence. The dissertation focuses on experimental investigation of the pseudo-dissipation. Indeed this quantity is difficult to measure as it requires the knowledge of all the possible derivatives of the three dimensional velocity field. Once considering an hot-wire technique to measure dissipation we need to deal with surrogates of dissipation, since not all the terms can be measured. The analysis of surrogates is the main topic of this work. In particular two flows, the turbulent channel and the turbulent jet, are considered. These canonic flows, introduced in a brief fashion, are often used as a benchmark for CFD solvers and experimental equipment due to their simple structure. Observations made in the canonic flows are often transferable to more complicated and interesting cases, with many industrial applications. The main tools of investigation are DNS simulations and experimental measures. DNS data are used as a benchmark for the experimental results since all the components of dissipation are known within the numerical simulation. The results of some DNS were already available at the start of this thesis, so the main work consisted in reading and processing the data. Experiments were carried out by means of hot-wire anemometry, described in detail on a theoretical and practical level. The study of DNS data of a turbulent channel at Re=298 reveals that the traditional surrogate can be improved Consequently two new surrogates are proposed and analysed, based on terms of the velocity gradient that are easy to measure experimentally. We manage to find a formulation that improves the accuracy of surrogates by an order of magnitude. For the jet flow results from a DNS at Re=1600 of a temporal jet, and results from our experimental facility CAT at Re=70000, are compared to validate the experiment. It is found that the ratio between components of the dissipation differs between DNS and experimental data. Possible errors in both sets of data are discussed, and some ways to improve the data are proposed.

Studio fluidodinamico di un reattore continuo agitato meccanicamente tramite tecniche PIV e PLIF

The study and understanding of the motion of the fluid phases in a mechanically stirred reactor has always been, and still are, an open problem which absorbs the study and the work of many researchers. In recent decades, thanks to the growing opportunities offered by the development of technology, we have made great strides in the understanding of mixing, one of the major unit operations at the base of many industrial processes. A complete understanding of this process and its optimization for industrial applications is a challenging task due to the complex interactions between the many factors at play that include physical, chemical and biological. The purpose of this thesis is the study of a fluid-mechanically-agitated continuous reactor through the use of optical diagnostic techniques, which allowed to determine the range of motion and the time of perfect homogenization in a reactor of standard geometry in different operating conditions.

Development of an instrumented customizable total knee prosthesis for experimental tests.

Total knee arthroplasty (TKA) has revolutionized the life of millions of patients and it is the most efficient treatment in cases of osteoarthritis. The increase in life expectancy has lowered the average age of the patient, which requires a more enduring and performing prosthesis. To improve the design of implants and satisfying the patient's needs, a deep understanding of the knee Biomechanics is needed. To overcome the uncertainties of numerical models, recently instrumented knee prostheses are spreading. The aim of the thesis was to design and manifacture a new prototype of instrumented implant, able to measure kinetics and kinematics (in terms of medial and lateral forces and patellofemoral forces) of different interchangeable designs of prosthesis during experiments tests within a research laboratory, on robotic knee simulator. Unlike previous prototypes it was not aimed for industrial applications, but purely focusing on research. After a careful study of the literature, and a preliminary analytic study, the device was created modifying the structure of a commercial prosthesis and transforming it in a load cell. For monitoring the kinematics of the femoral component a three-layers, piezoelettric position sensor was manifactured using a Velostat foil. This sensor has responded well to pilot test. Once completed, such device can be used to validate existing numerical models of the knee and of TKA and create new ones, more accurate.It can lead to refinement of surgical techniques, to enhancement of prosthetic designs and, once validated, and if properly modified, it can be used also intraoperatively.

Synthesis of KOH-based geopolymers for innovative applications

This study presents an evaluation on compressive strength of metakaolin-based geopolymers synthetized by using different activators, KOH and NaOH. The influence of NaOH/KOH concentration ratio together with curing temperature and time were investigated to find the best results from the compressive strength tests of metakaolin-based geopolymers, synthesized with a commercial metakaolin. Aggregates of small grain size referred as fillers, were added to reduce brittleness, and minimize the pore size and shrinkage of the final mixture creating a stronger network. In this work, silt recovered from industrial processes of wash water used for aggregates production was used as a filler in the production of KOH-based geopolymers, examining the possible influence on the mechanical strength of the final product. The curing temperatures chosen for the synthesis were 85°C, 60°C and 40°C. The samples were tested after 7 days and 28 days, according to the UNI EN 1015-11:2019 applied on Ca-based cements, analyzing the differences in mechanical strength comparing samples with similar and different compositions. The study presented in total 72 synthetized geopolymer specimens that were analyzed with unconfined compression test (UCT). The characterization of the starting materials metakaolin and silt was carried out using X- ray diffraction analysis (XRD). Whereas, the formed geopolymers were analyzed using X- ray diffraction (XRD), and scanning electron microscopy (SEM) with energy dispersive X- ray spectroscopy (EDS).

On the Role of Automatic Guided Vehicles in the 4th Industrial Revolution

Elaborate presents automated guided vehicle state-of-art, describing AGVs' types and employed technologies. AGVs' applications is going to be exposed by means of performed work during Toyota's internship. It will be presented the acquired experience on automatic forklifts' implementation and tools employed in a realization of an AGV system. Morover, it will be presented the development of a python program able to retrieve data, stored in a database, and elaborate them to produce heatmaps on vehicles' errors. The said program has been tested live on customer's sites and obtained result will be explained. Finally, it is going to be presented the analysis on natural navigation technology applied to Toyota's AGVs. Tests on natural navigation have been run in warehouses to estimate capabilities and possible application in logistic field.

Polymerization of isatin towards polymers for anion exchange membranes and gas separation applications

In a world where the problem of energy resources, pollution and all aspects related to these issues become more and more dominant, a greater commitment is needed in the search for solutions. The goal of this project is to make a contribution to the research and development of new materials to reduce the environmental impact in some fields. First of all, we tried to synthesize and prepare an isatin-based membrane which has the potential for use in separating industrial gases. Furthermore, ion exchange membranes, specifically hydroxide exchange membranes (HEMs) derived from the same product can be developed for fuel cells (HEMFC) applications. These materials are essential for energy conversion and storage. The most difficult challenge is to guarantee their thermal stability and stability in corrosive environments such as alkali without losing efficiency. In recent years the poly- hydroxyalkylation catalysed with superacids, e.g. TFSA, has become increasingly studied. This reaction is exploited for the synthesis of the compounds of this thesis. After a preliminary optimization of the reaction conditions it was concluded that due to the rigidity and excessive reactivity of the system, it was not possible to obtain the isatin-based membrane to evaluate the gas separation properties. The synthesis of precursor materials for HEMs was successful by using 1-(4-bromobutyl)indoline-2,3-dione (BID) instead of isatin. A characterization of the obtained polymers was carried out using NMR, TGA and DSC analyses, and subsequently the membranes were functionalized with different ammonium-based cations. Unfortunately, this last step was not successful due to the appearance of side reactions. Future studies on the mechanism and kinetics of the reaction solve this obstacle.

HBIM to Virtual Reality Workflow for Industrial Archaeology Immovable Assets’ Management: A Case Study

As a witness on the industrialization in Bologna, since its first generation was born in the late 1760, the Battiferro lock has been coping with the innovation that the city experienced throughout the centuries, until it has lost its functionality due to the technological development for which Bologna’s canals were gradually covered starting from the 1950s under Giuseppe Dozza ’s administration, as part of the reconstruction, reclamation and urban requalification that was carried out in the aftermath the World War II and which involved the whole city. The interest of the research carried out on this case study was primarily to reintroduce the landmark that is still intact, to what is considered to be the fourth generation of the industrial revolution, namely in the construction field, which is recognized as Construction 4.0, by means of the Historic (or Heritage) Information Modeling HBIM and Virtual Reality (VR) application. A scan-to-BIM approach was followed to create 3D as-built BIM model, as a first step towards the storytelling of the abandoned industrial built asset in VR environment, or as a seed for future applications such as Digital Twins (DT), heritage digital learning, sustainable impact studies, and/or interface with other interfaces such as GIS. Based on the HBIM product, examples of the primary BIM deliverables such as 2D layouts is given, then a workflow to VR is proposed and investigated the reliability of data and the type of users that may benefit of the VR experience, then the potential future development of the model is investigated, with comparison of a relatively similar experience in the UK.