Designing lead-free piezoelectric ceramics with tailored electrical properties remains a critical challenge for various applications. In this paper we present a novel methodology integrating Machine Learning (ML) and optimization procedures to fine-tune electrical properties in lead-free (1-x) Na0.5 Bi0.5 TiO3 - x CaTiO3 piezoelectric ceramics. A comprehensive dataset of dielectric measurements serves as the foundation for training ML models that accurately predict the permittivity (𝜀′) and dielectric loss (tan 𝛿) as functions of Ca2+concentration (x % Ca), temperature and frequency. Two ML techniques are evaluated: random forest regression, and Multi-Layer Perceptron neural network Regression (MLPR). The MLPR model exhibited a superior regression performance, achieving a correlation coefficient of 0.931 and a root mean squared error of 0.029. The MLPR was then optimized by the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to maximizes 𝜀′ while minimizes tan 𝛿. Within the NSGA-II framework, the optimal values were found at the Pareto curve knee, corresponding to a frequency, temperature, and x % Ca of 609.739 kHz, 398.15 K, and 6.10, respectively, resulting in 𝜀′ equal to 857.87 and tan 𝛿 equal to 0.0120. This approach demonstrates the effectiveness of combining ML andoptimization for designing the electrical properties of piezoelectric ceramics, paving the way for more efficient and targeted material development.
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An important issue in the field of motion control of wheeled mobile robots is that the design of most controllers is based only on the robot’s kinematics. However, when high-speed movements and/or heavy load transportation are required, it becomes essential to consider the robot dynamics as well. The control signals generated by most dynamic controllers reported in the literature are torques or voltages for the robot motors, while commercial robots usually accept velocity commands. In this context, we present a velocity-based dynamic model for differential drive mobile robots that also includes the dynamics of the robot actuators. Such model has linear and angular velocities as inputs and has been included in Peter Corke’s Robotics Toolbox for MATLAB, therefore it can be easily integrated into simulation systems that have been built for the unicycle kinematics. We demonstrate that the proposed dynamic model has useful mathematical properties. We also present an application of such model on the design of an adaptive dynamic controller and the stability analysis of the complete system, while applying the proposed model properties. Finally, we show some simulation and experimental results and discuss the advantages and limitations of the proposed model.
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İnsan vücudu ile elektromanyetik dalgaların etkileşimi, dokuların ve hücrelerin dielektrik özellikleri gibi faktörlerin yanı sıra diğer etkenler tarafından da şekillenir. Mikrodalga hipertermi ve mikrodalga görüntüleme uygulamalarında, deney ortamı ölçüm düzeneklerinde simülasyon sonuçlarını doğrulamak için doku taklit eden materyallere ihtiyaç vardır. Bu çalışmada hipertermi uygulamalarında kullanılmak üzere kadın memelerine ait bazı doku taklit materyallerinin karakterizasyonu sunulmuştur. Karakterize edilen doku taklit malzemelerinin maliyeti ucuz ve üretim aşamaları kolaydır. Deri, kas, meme yağı ve kanserli dokular ISM bandı 434 MHz'de önerilmektedir. The interaction of electromagnetic waves with the human body is determined by the dielectric properties of tissues and cells along with other considerations. The complex dielectric properties of the materials are very important for the interaction of the electromagnetic waves within the human body. In microwave hyperthermia and microwave imaging applications, there is a need of tissue mimicking materials to validate the simulation results in in vitro measurement setups. In this paper, we presented the characterization of some tissue materials belonging to female breast to be used for hyperthermia applications. The characterized tissue mimicking materials are inexpensive and have simple recipes that are easy to formulate. Skin, muscle, breast fat and cancerous tissues are proposed at ISM band 434 MHz.
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This paper assesses wind resource characteristics and energy yield for micro wind turbines integrated on noise barriers. An experimental set-up with sonic anemometers placed on top of the barrier in reference positions is realized. The effect on wind speed magnitude, inflow angle and turbulence intensity is analysed. The annual energy yield of a micro wind turbine is estimated and compared using data from a micro-wind turbine wind tunnel experiment and field data. Electrical energy costs are discussed as well as structural integration cost reduction and the potential energy yield could decrease costs. It was found that instantaneous wind direction towards the barrier and the height of observation play an influential role for the results. Wind speed increases in perpendicular flows while decreases in parallel flow, by +35% down to −20% from the reference. The azimuth of the noise barrier expressed in wind field rotation angles was found to be influential resulted in 50%–130% changes with respect to annual energy yield. A micro wind turbine (0.375 kW) would produce between 100 and 600 kWh annually. Finally, cost analysis with cost reductions due to integration and the energy yield changes due to the barrier, show a LCOE reduction at 60%–90% of the reference value. https://doi.org/10.1016/j.jweia.2020.104206
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Electrification of transportation, communication, working and living continues worldwide. Televisions, telephones, servers are an important part of everyday life. These loads and most sustainable sources as well, have one thing in common: Direct Current. The Dutch research and educational programme ‘DC – road to its full potential’ studies the impact of feeding these appliances from a DC grid. An improvement in energy efficiency is expected, other benefits are unknown and practical considerations are needed to come to a proper comparison with an AC grid. This paper starts with a brief introduction of the programme and its first stages. These stages encompass firstly the commissioning, selection and implementation of a safe and user friendly testing facility, to compare performance of domestic appliances when powered with AC and DC. Secondly, the relationship between the DC-testing facility and existing modeling and simulation assignments is explained. Thirdly, first results are discussed in a broad sense. An improved energy efficiency of 3% to 5% is already demonstrated for domestic appliances. That opens up questions for the performance of a domestic DC system as a whole. The paper then ends with proposed minor changes in the programme and guidelines for future projects. These changes encompass further studying of domestic appliances for product-development purposes, leaving less means for new and costly high-power testing facilities. Possible gains are 1) material and component savings 2) simpler and cheaper exteriors 3) stable and safe in-house infrastructure 4) whilst combined with local sustainable generation. That is the road ahead. 10.1109/DUE.2014.6827758
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Binnen het projectonderwijs wordt nog vaak drooggezwommen. Enerzijds door de verstrekte projectopdrachten anderzijds door de suboptimalisatie van oplossingen. Deze zijn namelijk sterk afhankelijk van de verbonden modules en docenten. In de praktijk zijn de oplossingen echter altijd een afweging van tijd, geld en kwaliteit. Onze Human Engineers leren om daar op een goede manier mee om te gaan. Dit door de integratiemodule Integrated Product Development (IPD). IPD is een multidisciplinair project waarbij studenten van verschillende Fontys Instituten werken aan de commercikle en technische uitwerking van een bedrijfsopdracht. Marktonderzoek, doelgroep bepaling en productspecificatie zijn een vast onderdeel van een IPD project evenals het ontwerpen en bouwen van een prototype en het financieel onderbouwen van een Go/NO go advies aan de ondernemer. Het project vindt plaats in het laatste onderwijssemester, net vssr het afstuderen en is dus te zien als een open project met een bedrijf als opdrachtgever. De Human Engineering studenten zijn in deze projecten de verbindende schakel. De specialisten in de projectgroepen, de technische studenten, willen nogal eens zoeken naar mooie oplossingen vooral in technische zin. Daarbij gaan ze vaak volledig voorbij aan het belang van de ondernemer (winst maken) en het belang van de klant (kwaliteit en bedieningsgemak). Ook het projectwerk heeft een enorme sprong vooruit gemaakt door het team uit te breiden met Human Engineers. De Human Engineering studenten focussen vooral ook op het halen van targets (kosten) en deadlines (tijd), het maken en nakomen van afspraken en de communicatie binnen de groep en naar buiten toe (ondernemer en klant). Huidige studenten en alumni geven aan dat het project zeer realistisch is en dat het vergelijkbaar is met problemen die ze in hun werk tegen komen. Zeker blijven doen is hun advies. Organisatorisch vergt het wel een en ander omdat er bijvoorbeeld afstemming dient te komen tussen de verschillende instituten met betrekking tot: beoordeling van de studenten, afstemmen van lesroosters en vergoeding voor docenten. Ook het onderhouden van bedrijfsrelaties om bijvoorbeeld aan de opdrachten te komen blijft een moeilijke, tijdrovende zaak.
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Innovation seems to be the most important element of activities of companies to stay vital in a very competitive international market. Innovation is the process of developing products or services in an organisation for a market. Especially small and medium-sized companies, for which it is difficult to invest in innovation research and development, need to be provided with young professionals to help them make the right decisions on innovation development. At the moment higher professional education in the Netherlands is not preparing students enough as future professionals in SMEs, for the task if initiating and to developing innovations in these SME's. Therefore it is needed that higher professional education comprehensively implement these innovation competences in its curriculum. At the Fontys University of Applied Sciences in Eindhoven, the Netherlands, innovation has become an important element in teaching students innovation competences. In 2007/8 a pilot has been introduced the department of Engineering with first year students in a multidisciplinary and action-based setting. First year students of Mechanical and Electrical Engineering in a 5-credit programme try to find new patentable products. The outcome of this first try-out was that students realized the importance of innovation for the profession and they were eager to work in this innovative setting. Some adjustments in the education will be made as there are: timetable and project settings to timetables and schedules will have to be made.
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Vibrational and structural properties of lead-free piezoelectric (1-x)Na0.5Bi0.5TiO3–xCaTiO3 (0 < x < 1.00) solid solutions have been investigated using Raman spectroscopy and X-ray diffraction. Different anomalies were detected and analyzed taking into consideration the phase transition from rhombohedral to orthorhombic phase at room temperature. All Raman bands were interpreted through the variation in the peak positions (frequency) and the corresponding half-widths at half maximum (HWHM) as a function of x. XRD used as a complementary technique to Raman spectroscopy, showed that the rhombohedral – orthorhombic phase transition went gradually through an intermediate phase consisting of a mixture of rhombohedral (R3c) and orthorhombic (Pnma) structures and that the fraction of orthorhombic phase increased with CT composition. The results show that the morphotropic phase boundary (MPB) is located between 0.09 and 0.15.
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In the rapidly evolving field of Machine Learning , selecting the most appropriate model for a given dataset is crucial. Understanding the characteristics of a dataset can significantly influence the outcomes of predictive modeling efforts, making the study of the properties of the dataset an essential component of data science. This study investigates the possibilities of using simulated human data for personalized applications, specifically for testing clustering approaches. In particular, the study focuses on the relationship between dataset characteristics and the selection of the optimal classification model for clusters of datasets. The results of this study provide critical insights for researchers and practitioners in machine learning, emphasizing the importance of dataset characteristics and variability in building and selecting robust models for diverse data conditions. The use of human simulation data provide valuable insights but requires further refinement to capture the full variability of real-world conditions.
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With a market demand for low cost, easy to produce, flexible and portable applications in healthcare, energy, biomedical or electronics markets, large research programs are initiated to develop new technologies to provide this demand with new innovative ideas. One of these fast developing technologies is organic printed electronics. As the term printed electronics implies, functional materials are printed via, e.g. inkjet, flexo or gravure printing techniques, on to a substrate material. Applications are, among others, organic light emitting diodes (OLED), sensors and Lab-on-a-chip devices. For all these applications, in some way, the interaction of fluids with the substrate is of great importance. The most used substrate materials for these low-cost devices are (coated) paper or plastic. Plastic substrates have a relatively low surface energy which frequently leads to poor wetting and/or poor adhesion of the fluids on the substrates during printing and/ or post-processing. Plasma technology has had a long history in treating materials in order to improve wetting or promote adhesion. The µPlasma patterning tool described in this thesis combines a digital inkjet printing platform with an atmospheric dielectric barrier discharge plasma tool. Thus enabling selective and local plasma treatment, at atmospheric pressure, of substrates without the use of any masking materials. In this thesis, we show that dependent on the gas composition the substrate surface can either be functionalized, thus increasing its surface energy, or material can be deposited on the surface, lowering its surface energy. Through XPS and ATR-FTIR analysis of the treated (polymer) substrate surfaces, chemical modification of the surface structure was confirmed. The chemical modification and wetting properties of the treated substrates remained present for at least one month after storage. Localized changes in wettability through µPlasma patterning were obtained with a resolution of 300µm. Next to the control of wettability of an ink on a substrate in printed electronics is the interaction of ink droplets with themselves of importance. In printing applications, coalescence of droplets is standard practice as consecutive droplets are printed onto, or close to each other. Understanding the behaviour of these droplets upon coalescence is therefore important, especially when the ink droplets are of different composition and/or volume. For droplets of equal volume, it was found that dye transport across the coalescence bridge could be fully described by diffusion only. This is as expected, as due to the droplet symmetry on either side of the bridge, the convective flows towards the bridge are of equal size but opposite in direction. For droplets of unequal volume, the symmetry across the bridge is no longer present. Experimental analysis of these merging droplets show that in the early stages of coalescence a convective flow from the small to large droplet is present. Also, a smaller convective flow of shorter duration from the large into the small droplet was identified. The origin of this flow might be due to the presence of vortices along the interface of the bridge, due to the strong transverse flow to open the bridge. To conclude, three potential applications were showcased. In the first application we used µPlasma patterning to create hydrophilic patterns on hydrophobic dodecyl-trichlorosilane (DTS) covered glass. Capillaries for a Lab-on-a-chip device were successfully created by placing two µPlasma patterned glass slides on top of each other separated by scotch tape. In the second application we showcased the production of a RFID tag via inkjet printing. Functional RFID-tags on paper were created via inkjet printing of silver nanoparticle ink connected to an integrated circuit. The optimal operating frequency of the produced tags is in the range of 860-865 MHz, making them usable for the European market, although the small working range of 1 m needs further improvement. Lastly, we showed the production of a chemresistor based gas sensor. In house synthesised polyemeraldine salt (PANi) was coated by hand on top of inkjet printed silver electrodes. The sensor proved to be equally sensitive to ethanol and water vapour, reducing its selectivity in detecting changes in gas composition.
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