@article{54966, abstract = {{Piezoresponse force microscopy (PFM) is one of the most widespread methods for investigating and visualizing ferroelectric domain structures down to the nanometer length scale. PFM makes use of the direct coupling of the piezoelectric response to the crystal lattice, and hence, it is most often applied to spatially map the three-dimensional (3D) near-surface domain distribution of any polar or ferroic sample. Nonetheless, since most samples investigated by PFM are at least semiconducting or fully insulating, the electric ac field emerging from the conductive scanning force microscopy (SFM) tip penetrates the sample and, hence, may also couple to polar features that are deeply buried into the bulk of the sample under investigation. Thus, in the work presented here, we experimentally and theoretically explore the contrast and depth resolution capabilities of PFM, by analyzing the dependence of several key parameters. These key parameters include the depth of the buried feature, i.e., here a domain wall (DW), as well as PFM-relevant technical parameters such as the tip radius, the PFM drive voltage and frequency, and the signal-to-noise ratio. The theoretical predictions are experimentally verified using x-cut periodically poled lithium niobate single crystals that are specially prepared into wedge-shaped samples, in order to allow the buried feature, here the DW, to be “positioned” at any depth into the bulk. This inspection essentially contributes to the fundamental understanding in PFM contrast analysis and to the reconstruction of 3D domain structures down to a 1 μm-penetration depth into the sample.}}, author = {{Roeper, Matthias and Seddon, Samuel D. and Amber, Zeeshan H. and Rüsing, Michael and Eng, Lukas M.}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, keywords = {{Ferroelectrics, lithium niobate, piezoresponse force microscopy}}, number = {{22}}, publisher = {{AIP Publishing}}, title = {{{Depth resolution in piezoresponse force microscopy}}}, doi = {{10.1063/5.0206784}}, volume = {{135}}, year = {{2024}}, } @article{43441, abstract = {{This paper reveals the 3D character of the intermetallic layer at the aluminum–steel interface which pops up above the original sample surface during annealing. Popping out of the intermetallics was proven using atomic force microscopy. The phase expands out of the plane due to the exothermic formation of the Al5Fe2 phase and the feasibility of surface diffusion. Milling by a focused ion beam enabled the comparison of the chemical composition of the surface layer with the bulk interface, showing no difference. The growth direction is both towards aluminum and steel — the main diffusion flux is from aluminum towards steel, and the new intermetallic phase emerges at the steel side. The shortage of Al atoms causes a shift of the intermetallic as a whole towards aluminum.}}, author = {{Šlapáková, Michaela and Kihoulou, Barbora and Veselý, Jozef and Minárik, Peter and Fekete, Klaudia and Knapek, Michal and Králík, Rostislav and Grydin, Olexandr and Stolbchenko, Mykhailo and Schaper, Mirko}}, issn = {{0042-207X}}, journal = {{Vacuum}}, keywords = {{Al-steel clad, twin-roll casting, 3D characterization, atomic force microscopy, diffusion direction, surface growth}}, publisher = {{Elsevier BV}}, title = {{{3D-structure of intermetallic interface layer in Al–steel clad material}}}, doi = {{10.1016/j.vacuum.2023.112043}}, volume = {{212}}, year = {{2023}}, } @inbook{34707, abstract = {{Of the many outstanding female philosophers of the European Enlightenment, Emilie Du Châtelet excelled as a physicist, a philosopher, and a mathematician, as well as a Bible critic. She was famous in her lifetime and was not completely forgotten thereafter. Among her admirers, correspondents and friends were the most acknowledged scholars of her time, including Voltaire, Clairault, Maupertuis, Diderot, Helvetius, La Mettrie, Buffon, Christian Wolff, Leonard Euler, and Johann II Bernoulli. Her philosophical work enjoyed high reputation and her opus magnum, the Institutions physiques, was translated into Italian and German and proved her to be an intellectual of European stature. Its defense of living forces and its implied forecast into dynamics as well as her methodological grounding of scientific knowledge as hypothetical, impacted philosophy and science. Reality must by nature escape us. What we perceive are phenomena. Du Châtelet explains the function of space and time to trace us back to the origin of phenomena. Her influence on Kant is evident. Next to her writings in physics, mathematics, philosophy, language, and logic, she contributed to morality and ethics. Du Châtelet left an opus of quite systematic breadth. This impressive publishing activity excels in the amount of its scientific and philosophical production to which a vast collection of manuscripts must be added.She argued against prejudice and idolatry in philosophy and science. Science is a cooperative undertaking over history and beyond nations. Her moral writings align with ideas of the French materialists. Du Châtelet translated and commented on Newton’s Principia, preparing thus the fertile soil of the generation of physicists to come in France.}}, author = {{Hagengruber, Ruth}}, booktitle = {{Encyclopedia of Early Modern Philosophy and the Sciences}}, isbn = {{9783319207919}}, keywords = {{aura Bassi Luise Gottsched Immanuel Kant Dourtous de Mairan Johann II Bernoulli Algarotti Buffon d’Alembert La Mettrie Principle of contradiction Hypotheses Enlightenment Leibniz-Clarke Correspondence Living forces Dead forces, happiness Space Imaginary beings Monads Epicurus Ethics Women philosophers Newton’s laws Principia Motion inertia Active force Vis viva Vis mortua Hypothetic reasoning Hypotheses, a priori principles, Experience, Dead forces, Living forces, Energy Dynamics}}, publisher = {{Springer International Publishing}}, title = {{{Du Châtelet, Émilie (1706–1749)}}}, doi = {{10.1007/978-3-319-20791-9_410-1}}, year = {{2021}}, } @article{1452, abstract = {{Opinion leaders of an investment network can have a significant impact on capital mar-kets because their investment decisions are adopted by their peers and trigger large trad-ing cascades, increasing herding behavior and comovement among stock returns. This paper analyzes the interaction-based relations of traders from a large social trading plat-form and identifies the driving forces and the opinion leaders within a large online trading network as the nodes with the highest centrality and the highest force of infection, respec-tively. Relying on recent insights from epidemiological research, I maintain that central-ity identifies the most central traders in the network, while the expected force quantifies the most influential traders and their spreading power. I study the behavior and charac-teristics that set central and influential traders apart from other traders. The ability to identify focal points and their trading behavior within a trading network is important for investors, investment advisers, and policy makers.}}, author = {{Pelster, Matthias}}, journal = {{Proceedings of the International Conference on Information Systems}}, keywords = {{Online trading, investment advice, network modeling, Expected Force, herding.}}, title = {{{I’ll Have What S/he’s Having: A Case Study of a Social Trading Network}}}, year = {{2017}}, } @article{13241, abstract = {{The accuracy of water models derived from ab initio molecular dynamics simulations by means on an improved force-matching scheme is assessed for various thermodynamic, transport, and structural properties. It is found that although the resulting force-matched water models are typically less accurate than fully empirical force fields in predicting thermodynamic properties, they are nevertheless much more accurate than generally appreciated in reproducing the structure of liquid water and in fact superseding most of the commonly used empirical water models. This development demonstrates the feasibility to routinely parametrize computationally efficient yet predictive potential energy functions based on accurate ab initio molecular dynamics simulations for a large variety of different systems. © 2016 Wiley Periodicals, Inc.}}, author = {{Köster, Andreas and Spura, Thomas and Rutkai, Gábor and Kessler, Jan and Wiebeler, Hendrik and Vrabec, Jadran and Kühne, Thomas D.}}, journal = {{Journal of Computational Chemistry}}, keywords = {{liquid water, force matching, ab initio, molecular dynamics, Monte Carlo}}, number = {{19}}, pages = {{1828--1838}}, title = {{{Assessing the accuracy of improved force-matched water models derived from Ab initio molecular dynamics simulations}}}, doi = {{10.1002/jcc.24398}}, volume = {{37}}, year = {{2016}}, } @inproceedings{9868, abstract = {{In order to increase mechanical strength, heat dissipation and ampacity and to decrease failure through fatigue fracture, wedge copper wire bonding is being introduced as a standard interconnection method for mass production. To achieve the same process stability when using copper wire instead of aluminum wire a profound understanding of the bonding process is needed. Due to the higher hardness of copper compared to aluminum wire it is more difficult to approach the surfaces of wire and substrate to a level where van der Waals forces are able to arise between atoms. Also, enough friction energy referred to the total contact area has to be generated to activate the surfaces. Therefore, a friction model is used to simulate the joining process. This model calculates the resulting energy of partial areas in the contact surface and provides information about the adhesion process of each area. The focus here is on the arising of micro joints in the contact area depending on the location in the contact and time. To validate the model, different touchdown forces are used to vary the initial contact areas of wire and substrate. Additionally, a piezoelectric tri-axial force sensor is built up to identify the known phases of pre-deforming, cleaning, adhering and diffusing for the real bonding process to map with the model. Test substrates as DBC and copper plate are used to show the different formations of a wedge bond connection due to hardness and reaction propensity. The experiments were done by using 500 $\mu$m copper wire and a standard V-groove tool.}}, author = {{Althoff, Simon and Neuhaus, Jan and Hemsel, Tobias and Sextro, Walter}}, booktitle = {{Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th}}, keywords = {{adhesion, circuit reliability, deformation, diffusion, fatigue cracks, friction, interconnections, lead bonding, van der Waals forces, Cu, adhering process, adhesion process, ampacity improvement, bond quality improvement, cleaning process, diffusing process, fatigue fracture failure, friction energy, friction model, heat dissipation, mechanical strength, piezoelectric triaxial force sensor, predeforming process, size 500 mum, total contact area, van der Waals forces, wedge copper wire bonding, Bonding, Copper, Finite element analysis, Force, Friction, Substrates, Wires}}, pages = {{1549--1555}}, title = {{{Improving the bond quality of copper wire bonds using a friction model approach}}}, doi = {{10.1109/ECTC.2014.6897500}}, year = {{2014}}, } @inproceedings{9568, abstract = {{A simple pre-stress estimate method of Langevin transducers is studied. The measurement setup consists of a capacitor, an impedance converter and a voltmeter. Based on the piezoelectric equation and the basic circuit theory, the mathematical expression between the pre-stress and the voltage across the capacitor is derived. The pre-stress level can then be calculated out of the measurement of the capacitor voltage. In order to evaluate the precision of this method, a force washer is used to measure the pre-stress of the Langevin transducer. The result shows the pre-stress level obtained from this method is 30-40\% higher than the pre-stress level measured by the force washer. This method is simple and can be used to estimate the pre-stress of various Langevin transducers. The precision of this method can be raised if d33 is identified under different pre-stress levels.}}, author = {{Bo, Fu and Ting, Li and Hemsel, Tobias}}, booktitle = {{Piezoelectricity, Acoustic Waves, and Device Applications, 2008. SPAWDA 2008. Symposium on}}, keywords = {{capacitors, impedance convertors, piezoelectric transducers, stress analysis, Langevin transducers, basic circuit theory, capacitor, impedance converter, piezoelectric equation, pre-stress estimating method, voltmeter, Capacitors, Educational institutions, Equations, Force measurement, Impedance measurement, Manufacturing, Mechatronics, Piezoelectric transducers, Voltage, Voltmeters, Langevin transducer, capacitor, piezoelectric element, pre-stress}}, pages = {{324--327}}, title = {{{A simple pre-stress estimating method of langevin transducers}}}, doi = {{10.1109/SPAWDA.2008.4775801}}, year = {{2008}}, } @inproceedings{8915, abstract = {{Ultrasonic linear motors have now been investigated for several years. Their key features are high thrust forces related to their volume and good position-accuracy. This contribution consists of two main parts. In the first part we describe the state-of-the-art of linear piezoelectric motors. Characteristics like no-load velocity, maximum thrust force and other technical properties of commercially available devices will be reported as well as those of prototypes. In the second part we report an ongoing research and development project aiming at a linear piezoelectric motor, which is capable of surpassing some of the shortcomings of other piezoelectric motors}}, author = {{Hemsel, Tobias and Wallaschek, Jörg}}, booktitle = {{Ultrasonics Symposium, 2000 IEEE}}, issn = {{1051-0117}}, keywords = {{linear motors, ultrasonic motors, linear piezoelectric motor, maximum thrust force, no-load velocity, ultrasonic linear motor, Electromagnetic devices, Electromagnetic fields, Frequency, Friction, Gears, Materials science and technology, Piezoelectric materials, Research and development, Vibrations, Wheels}}, pages = {{663--666 vol.1}}, title = {{{State of the art and development trends of ultrasonic linear motors}}}, doi = {{10.1109/ULTSYM.2000.922635}}, volume = {{1}}, year = {{2000}}, }