44 research outputs found

    State transition and electrocaloric effect of BaZrx_{x}Ti1−x_{1-x}O3_3: simulation and experiment

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    The electrocaloric effect (ECE) of BaZrx_{x}Ti1−x_{1-x}O3_3 (BZT) is closely related to the relaxor state transition of the materials. This work presents a systematic study on the ECE and the state transition of the BZT, using a combined canonical and microcanonical Monte Carlo simulations based a lattice-based on a Ginzburg-Landau-type Hamiltonian. For comparison and verification, experimental measurements have been carried on BTO and BZT (x=0.12x=0.12 and 0.20.2) samples, including the ECE at various temperatures, domain patterns by Piezoresponse Force Microscopy at room temperature, and the P-E loops at various temperatures. Results show that the dependency of BZT behavior of the Zr-concentration can be classified into three different stages. In the composition range of 0≀x≀0.2 0 \leq x \leq 0.2 , ferroelectric domains are visible, but ECE peak drops with increasing Zr-concentration harshly. In the range of 0.3≀x≀0.7 0.3 \leq x \leq 0.7 , relaxor features become prominent, and the decrease of ECE with Zr-concentration is moderate. In the high concentration range of x≄0.8 x \geq 0.8 , the material is almost nonpolar, and there is no ECE peak visible. Results suggest that BZT with certain low range of Zr-concentration around x=0.12∌0.3x=0.12 \sim 0.3 can be a good candidate with relatively high ECE and simutaneously wide temperature application range at rather low temperature

    Thick film PZT transducer arrays for particle manipulation

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    This paper reports the fabrication and evaluation of a two-dimensional thick film PZT ultrasonic transducer array operating at about 7.5 MHz for particle manipulation. All layers on the array are screen-printed and sintered on an Al2O3 substrate without further processes or patterning. The measured dielectric constant of the PZT is 2250 ± 100, and the dielectric loss is 0.09 ± 0.005 at 10 kHz. Finite element analysis has been used to predict the behaviour of the array and impedance spectroscopy and laser vibrometry have been used to characterise its performance. The measured deflection of a single activate element is on the order of tens of nanometres with 20 Vpp input. Particle manipulation experiments have been performed by coupling the thick film array to a capillary containing polystyrene microspheres in water

    IAB-Haushaltspanel LebensqualitÀt und soziale Sicherung : Interviewerhandbuch Welle 5 - 2011

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    "Im Zeitraum von Februar bis Juni 2011 werden ca. 12.000 Haushalte und etwa 20.000 Personen in Deutschland zu ihrer sozialen Sicherung und LebensqualitĂ€t befragt. Es handelt sich hierbei um die fĂŒnfte Befragungswelle der IAB-Panelstudie PASS. Der grĂ¶ĂŸte Teil der Haushalte wurde bereits viermal befragt und hat das EinverstĂ€ndnis fĂŒr ein weiteres Interview gegeben. Daneben wurden in jeder Welle auch neue Haushalte fĂŒr die Langzeitstudie ausgewĂ€hlt. Diese ca. 1.000 Haushalte werden jeweils zum ersten Mal befragt." Der Methodenreport gibt den Interviewern Hinweise zu den HintergrĂŒnden der Studie, zur DurchfĂŒhrung der Befragung, zur Kontaktaufnahme mit den Befragungshaushalten und zum Interviewer-Verhalten. Weiterhin werden Informationen zum Fragebogen gegeben. (IAB2)IAB-Haushaltspanel, Befragung - Handbuch, DurchfĂŒhrungsanweisung, Datengewinnung

    Computational Models for Clinical Applications in Personalized Medicine—Guidelines and Recommendations for Data Integration and Model Validation

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    The future development of personalized medicine depends on a vast exchange of data from different sources, as well as harmonized integrative analysis of large-scale clinical health and sample data. Computational-modelling approaches play a key role in the analysis of the underlying molecular processes and pathways that characterize human biology, but they also lead to a more profound understanding of the mechanisms and factors that drive diseases; hence, they allow personalized treatment strategies that are guided by central clinical questions. However, despite the growing popularity of computational-modelling approaches in different stakeholder communities, there are still many hurdles to overcome for their clinical routine implementation in the future. Especially the integration of heterogeneous data from multiple sources and types are challenging tasks that require clear guidelines that also have to comply with high ethical and legal standards. Here, we discuss the most relevant computational models for personalized medicine in detail that can be considered as best-practice guidelines for application in clinical care. We define specific challenges and provide applicable guidelines and recommendations for study design, data acquisition, and operation as well as for model validation and clinical translation and other research areas

    Screen-printed ultrasonic 2-D matrix array transducers for microparticle manipulation

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    This paper reports the development of a two-dimensional thick film lead zirconate titanate (PZT) ultrasonic transducer array, operating at frequency approximately 7.5 MHz, to demonstrate the potential of this fabrication technique for microparticle manipulation. All layers of the array are screen-printed then sintered on an alumina substrate without any subsequent patterning processes. The thickness of the thick film PZT is 139 ± 2 ÎŒm, the element pitch of the array is 2.3 mm, and the dimension of each individual PZT element is 2 × 2 mm2 with top electrode 1.7 × 1.7 mm2. The measured relative dielectric constant of the PZT is 2250 ± 100 and the dielectric loss is 0.09 ± 0.005 at 10 kHz. Finite element analysis was used to predict the behaviour of the array and to optimise its configuration. Electrical impedance spectroscopy and laser vibrometry were used to characterise the array experimentally. The measured surface motion of a single element is on the order of tens of nanometres with a 10 Vpeak continuous sinusoidal excitation. Particle manipulation experiments have been demonstrated with the array by manipulating Ø10 ÎŒm polystyrene microspheres in degassed water. The simplified array fabrication process and the bulk production capability of screen-printing suggest potential for the commercialisation of multilayer planar resonant devices for ultrasonic particle manipulation

    PMN-8PT device structures for electrocaloric cooling applications

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    Based on fundamental research carried out on PMN-8PT bulk ceramics, screen-printed thick films and multilayer ceramic (MLC) structures have been developed. The influence of device design on the microstructural, dielectric, ferroelectric and electrocaloric properties has been investigated in detail. MLC structures turned out to be promising candidates for implementation into electrocaloric cooling systems providing large refrigerant volume and low single layer thickness. The latter allows for the application of high electric fields under low operation voltages. An electrocaloric temperature change of DT = 0.21 K was measured directly, by application/withdrawal of an electric field ofDE = 2.1 kVmm-1

    »SensoTool«. Intelligente Produktionssysteme

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    Die Anforderungen an innovative Produkte werden zunehmend komplexer und die Angebotspalette kundenspezifischer. Dies erfordert eine Flexibilisierung und stĂ€ndige Kontrolle der Produktionssysteme. Das ist ein Ziel der sogenannten vierten industriellen Revolution. Um dieses zu erreichen, ist eine exakte echtzeitfĂ€hige Bestimmung des Prozesszustandes Grundvoraussetzung. Mit dem ProzessĂŒberwachungssystem "SensoTool" ist es erstmals möglich, den Zustand spanender Prozesse mittels wirkstellennaher Schnittkraftsensorik zu bestimmen

    Influence of Sintering Additives on Modified (Ba,Sr)(Sn,Ti)O<sub>3</sub> for Electrocaloric Application

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    This paper reports on the influence of sintering additives CuO and MgO on the recently developed lead-free electrocaloric (EC) material Ba0.82Sr0.18Sn0.065Ti0.935O3 (BSSnT-18-6.5). Details on the sintering behavior and the resulting microstructure of bulk ceramic samples prepared through solid-state synthesis and their dielectric, ferroelectric, and electrocaloric properties are presented. On the one hand, the addition of CuO (xCuO = 2%) significantly reduced the sintering temperature from 1400 °C to 1150 °C. On the other hand, the addition of MgO (xMgO = 1%) dramatically reduced the average grain size from 40 ”m to 0.4 ”m, leading to an increase in dielectric breakdown strength from 4.4 V ”m−1 to 7.7 V ”m−1. Thus, BSSnT-18-6.5 with the addition of MgO to bulk ceramic samples could achieve maximum EC temperature changes (|ΔTEC|) of 0.27 K around 30 °C with almost no aberration within a broad temperature range from 5 °C to 50 °C under an applied electric field change of 5 V ”m−1. The results show the potential of this material for the fabrication of multilayer ceramic (MLC) components for future electrocaloric applications

    Influence of Grain-Growth Inhibitors on Modified (Ba,Sr)(Sn,Ti)O<sub>3</sub> for Electrocaloric Application

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    The paper reports on effect of grain-growth inhibitors MgO, Y2O3 and MnCO3 as well as Ca modification on the microstructure, dielectric, ferroelectric and electrocaloric (EC) properties of Ba0.82Sr0.18Sn0.065Ti0.935O3 (BSSnT). Furthermore, the effects of the sintering time and temperature on the microstructure and the electrical properties of the most promising material system Ba0.62Ca0.20Sr0.18Sn0.065Ti0.935O3 (BCSSnT-20) are investigated. Additions of MgO (xMgO = 1%), Y2O3 (xY2O3 = 0.25%) and MnCO3 (xMnCO3 = 1%) significantly decreased the mean grain size of BSSnT to 0.4 ”m, 0.8 ”m and 0.4 ”m, respectively. Ba0.62Ca0.20Sr0.18Sn0.065Ti0.935O3 (BCSSnT-20) gained a homogeneous fine-grained microstructure with an average grain size of 1.5 ”m, leading to a maximum electrocaloric temperature change |ΔTEC| of 0.49 K at 40 °C with a broad peak of |ΔTEC| > 0.33 K in the temperature range from 10 °C to 75 °C under an electric field change of 5 V ”m−1. By increasing the sintering temperature of BCSSnT-20 from 1350 °C to 1425 °C, the grain size increased from 1.5 ”m to 7.3 ”m and the maximum electrocaloric temperature change |ΔTEC| increased from 0.15 K at 35 °C to 0.37 K at 20 °C under an electric field change of 2 V ”m−1. Our results show that under all investigated material systems, BCSSnT-20 is the most promising candidate for future application in multilayer ceramic (MLC) components for EC cooling devices
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