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71.
Design of LTCC with High Thermal Expansion 总被引:1,自引:0,他引:1
Markus Eberstein Carsten Glitzky Marion Gemeinert Torsten Rabe Wolfgang A. Schiller Christina Modes 《International Journal of Applied Ceramic Technology》2009,6(1):1-8
New applications of low-temperature co-fired ceramics (LTCC), such as pressure sensors or integrated functional layers, require materials that possess higher coefficients of thermal expansion (CTE). To fabricate LTCC with elevated CTE, two methods of material design are examined: firstly, glass ceramic composites (GCC), which consist of >50 vol% glass in the starting powder, and, secondly, glass-bonded ceramics (GBC), where glass is added as a sintering aid only. The CTE of GBC is mainly determined by the crystalline component. For GCC, the CTE can be well predicted, if CTE and elastic data of each phase in the microstructure are known. A nonlinear characteristic of the CTE versus phase composition was found with increasing E crystals / E glass ratio and absolute CTE difference between the components. The glass composition and glass amount can be used to compensate the fixed properties of a crystalline material in a desired way. However, because the CTE and permittivity of a glass cannot be chosen independently, an optimum glass composition has to be found. For a given LTCC, it is possible to control the devitrification by shifting the glass composition. In this way, the resulting CTE values can be predicted more exactly and tailoring becomes possible. Different LTCC materials, based on the crystalline compounds Ba(La,Nd)2 Ti4 O12 , ZrO2 (Y-TZP), SiO2 (quartz), and specially developed glasses, possessing an elevated CTE of around 10 × 10−6 K−1 while showing permittivity ɛr between 6 and 63, are introduced. 相似文献
72.
Uniform Pointwise Convergence of Finite Difference Schemes Using Grid Equidistribution 总被引:1,自引:0,他引:1
Torsten Linß 《Computing》2001,66(1):27-39
A singularly perturbed quasilinear two-point boundary value problem is considered. The problem is discretized using a simple
upwind finite difference scheme on adapted meshes using grid equidistribution of monitor functions. We derive sufficient conditions
on the monitor function that guarantee uniform convergence in the discrete maximum norm no matter how small the perturbation
parameter is. These results can be used to deduce uniform convergence of the scheme for a number of layer-adapted meshes.
We also propose an adaptive procedure for the numerical treatment of the boundary value problem. Numerical experiments for
the schemes are presented.
Received November 12, 1999; revised April 20, 2000 相似文献
73.
The authors investigated the impact of response activation on dual-task performance by presenting a subliminal prime before the stimulus in Task 2 (S2) of a psychological refractory period (PRP) task. Congruence between prime and S2 modulated the reaction times in Task 2 at short stimulus onset asynchrony despite a PRP effect. This Task 2 congruence effect was paralleled by a Task 1 congruence effect and emerged exclusively under conditions of cross talk, whereas it did not occur under dual-task conditions preventing cross talk between tasks. This suggests that response activation operates during the PRP in dual tasks and affects the response times in Task 2 via cross talk between common processing elements at prebottleneck stages but not by directly affecting the postbottleneck stages. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Jacob L. Jones Alain B. Kounga Emil Aulbach Torsten Granzow 《Journal of the American Ceramic Society》2008,91(5):1586-1590
In many polycrystalline piezoelectric ceramics, domain switching during the poling process leads to the development of a macroscopic polarization and piezoelectric behavior. Traditionally, poling involves the application of electric fields across two parallel electrodes. In the present work, a radial mechanical compressive stress is applied transverse to the electric field, increasing the potential for domain alignment during poling by taking advantage of ferroelasticity. Experiments demonstrate that poling of lead zirconate titanate using a combination of an electric field and a transverse mechanical compressive stress increases the d 33 coefficient from 435 to 489 pC/N. Using neutron diffraction and pole figure inversion methods, the degree of non-180° domain switching is described using pole density distributions of the tetragonal c -axis (002). The degree of 002 domain alignment parallel to the electric field after the electromechanical poling process increases from 1.30 multiples of a random distribution (mrd) to >1.40 mrd at stresses exceeding 40 MPa. 相似文献
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Reza Mirzaeitalarposhti Michael Scott Demyan Frank Rasche Maxim Poltoradnev Georg Cadisch Torsten Müller 《Nutrient Cycling in Agroecosystems》2015,102(2):265-283
Development of spectroscopic prediction models via partial least squares regression (PLSR) suggests that model performance is highly affected by means of calibration and nature of the dataset. This study compares the predictive performance of PLSR models obtained by cross-validation and independent validation to quantify physico-chemical soil properties from their mid-infrared diffuse reflectance Fourier transform spectra (midDRIFTS) across two contrasting regions, Kraichgau (K) and Swabian Alb (SA), in Southwest Germany. We evaluated the capability of midDRIFTS-PLSR models for predicting total carbon (TC), organic carbon (TOC), inorganic carbon (TIC), nitrogen (TN), mineral N (Nmin), C:N ratio, hot water extractable C and N (CHWE, NHWE), microbial biomass C and N (Cmic, Nmic), pH, bulk density, and clay, silt and sand contents of 126 soil samples. Based on calibrated models, most soil properties were predicted successfully using either calibration approach with residual prediction deviations ≥3 and R2 > 0.9, except for Nmin, C/N ratio, pH, bulk density and sand. However, predictive performance of generic independent validation derived models (GIC) of test set was considerably higher than generic cross-validation models. Validation using GIC models gave relatively the same predictive performance with those obtained in calibration except for Nmin. Validation of region specific cross-validated models, however, resulted in successful predictions only for TC, TIC, TOC and TN in SA and TC and TIC and TOC in K. Our results show the superiority of independent validation over both generic and region specific cross-validation as a robust tool for predicting soil properties without further laboratory measurements. 相似文献
79.
Kostantine Katcko Etienne Urbain Franck Ngassam Lalit Kandpal Bhavishya Chowrira Filip Schleicher Ufuk Halisdemir Di Wang Torsten Scherer Damien Mertz Benoit Leconte Nicolas Beyer Daniel Spor Pierre Panissod Arnaud Boulard Jacek Arabski Christophe Kieber Emmanuel Sternitzky Victor Da Costa Michel Hehn François Montaigne Armel Bahouka Wolfgang Weber Eric Beaurepaire Christian Kübel Daniel Lacour Mébarek Alouani Samy Boukari Martin Bowen 《Advanced functional materials》2021,31(15):2009467
The quantum states of nano-objects can drive electrical transport properties across lateral and local-probe junctions. This raises the prospect, in a solid-state device, of electrically encoding information at the quantum level using spin-flip excitations between electron spins. However, this electronic state has no defined magnetic orientation and is short-lived. Using a novel vertical nanojunction process, these limitations are overcome and this steady-state capability is experimentally demonstrated in solid-state spintronic devices. The excited quantum state of a spin chain formed by Co phthalocyanine molecules coupled to a ferromagnetic electrode constitutes a distinct magnetic unit endowed with a coercive field. This generates a specific steady-state magnetoresistance trace that is tied to the spin-flip conductance channel, and is opposite in sign to the ground state magnetoresistance term, as expected from spin excitation transition rules. The experimental 5.9 meV thermal energy barrier between the ground and excited spin states is confirmed by density functional theory, in line with macrospin phenomenological modeling of magnetotransport results. This low-voltage control over a spin chain's quantum state and spintronic contribution lay a path for transmitting spin wave-encoded information across molecular layers in devices. It should also stimulate quantum prospects for the antiferromagnetic spintronics and oxides electronics communities. 相似文献
80.