In situ hot-stage TEM of the phase and domain evolution in quenched Na1/2Bi1/2TiO3–BaTiO3

Quenching relaxor ferroelectric 0.94(Na_1/2Bi_1/2)TiO₃–0.06BaTiO₃ (NBT-6BT) enhances the depolarization temperature (T_d), linked to the stabilization of ferroelectric order. The thermal evolution of the domain structure and phase assemblage provides insights about the onset of ferroelectric order in quenched materials. Unpoled furnace cooled and quenched NBT-6BT ceramics were studied using in situ temperature-dependent transmission electron microscopy. The rhombohedral to tetragonal structural transition in furnace cooled and quenched samples occurs in a comparable temperature range of 120°C–220°C. While the tetragonal phase is characterized by polar nanoregions (PNRs) and no domain contrast in the furnace cooled state, the quenched composition exhibits an increased fraction of lamellar domains, which are partially stable up to 300°C, thus benefiting the delayed depolarization. This is further corroborated by the dielectric data indicating earlier freezing of PNR dynamics in the quenched state. The reversibility of the phase transition is demonstrated by successive cooling, where quenched NBT-6BT features an increased grainy PNR contrast after the experiment, followed by a kinetically delayed coalescence of PNRs back into lamellar domains. This demonstrates that the stabilized ferroelectric state upon quenching is associated with the conversion of polar units on the nanometer scale into long-range domain structures.     

Head- and tail-end dehulling of soybeans

Head-end and tail-end dehulling systems are compared, including yield, investment costs, and energy consumption. A comparison of the European and US methods of using head-end and tail-end dehulling is provided. A combination of front-end and tail-end dehulling systems is shown, including the results in yield. Power consumption and investment costs are presented in comparison to front-end dehulling.     

Nonlinear control of three‐dimensional underactuated vehicles

This paper presents the derivation of robust trajectory‐tracking nonlinear control laws for general three‐dimensional vehicle models with one degree of underactuation where all of the state tracking errors are stabilized. The method is based on a novel transformation of the trajectory tracking problem into a reduced‐order error dynamics. Two traditional nonlinear controllers based on sliding mode and backstepping approaches are developed and shown to stabilize the trajectory tracking errors in presence of modeling uncertainties and bounded disturbances. The performance of the two controllers are compared in absence and presence of disturbances.     

Die BEM-FEM-Kopplungsmethode zur Behandlung dreidimensionaler nichtlinearer Abschirmungsprobleme niederfrequenter Felder am Beispiel des TEAM Problems 21

Übersicht Die Anwendung der BEM-FEM Kopplung zur numerischen Behandlung von Abschirmproblemen wird vorgestellt. Dazu werden die Potentialgleichungen hergeleitet und ein Verfahren diskutiert, das die Erfüllung der Eichbedingung sicherstellt. Ausgehend von der schwachen Form des Randwertproblems wird die Kopplung zwischen finiten Elementen (FEM) und Randelementen (BEM) ausführlich abgeleitet. Zur iterativen Behandlung nichtlinearer Medien wird ein modifiziertes M(B)-Verfahren vorgestellt. Als Beispiel wird das TEAM Problem 21 (TestingElectromagneticAnalysisMethods) untersucht.

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The BEM-FEM coupling method for the solution of three dimensional nonlinear shielding problems of low frequency fields considering TEAM problem 21

Contents The application of the BEM-FEM coupling for the numerical solution of shielding problems is presented. For this purpose the potential equations are derived and a procedure ensuring the gauge condition is discussed. Starting with the weak formulation of the boundary value problem the coupling of finite Elements (FEM) and boundary elements (BEM) is derived in detail. For the iterative treatment of nonlinear media a modified M(B)-scheme is presented. As an example TEAM problem 21 (TestingElectromagneticAnalysisMethods) is investigated.

     

Information: Does it Have To Be True?

Luciano Floridi (2003) offers a theory of information as a “strongly semantic” notion, according to which information encapsulates truth, thereby making truth a necessary condition for a sentence to qualify as “information”. While Floridi provides an impressive development of this position, the aspects of his approach of greatest philosophical significance are its foundations rather than its formalization. He rejects the conception of information as meaningful data, which entails at least three theses – that information can be false; that tautologies are information; and, that “It is true that ...” is non-redundant – appear to be defensible. This inquiry offers various logical, epistemic, and ordinary-language grounds to demonstrate that an account of his kind is too narrow to be true and that its adoption would hopelessly obscure crucial differences between information, misinformation, and disinformation.     

Focused Development of Magnesium Alloys Using the Calphad Approach

In traditional alloy development, experimental investigations with many different alloy compositions are performed. The selection criteria for multicomponent alloying elements and their compositions become diffuse in a traditional approach. Computational thermochemistry as used in the Calphad approach can provide a clear guideline for such selections and helps to avoid large scale experiments with less promising alloys. Thus, it is a powerful tool to cut down on cost and time during development of Mg‐alloys. An overview of the Calphad method is given. As an example of applications, recent developments of new creep resistant magnesium alloys that show about 100 times less creep than the best commercial alloys are reported. Also outlined are the methods used in our long‐term project of construction of the necessary thermodynamic magnesium alloy database for several alloying elements, such as Al, Li, Si, Mn, Ca, Sc, Y, and Zr, and rare earth elements (Ce, Gd, Nd), using the Calphad method combined with key experiments.