Search results for "Partial"
showing 10 items of 1477 documents
Crystal Structure of New Heusler Compounds
2009
Heusler compounds are promising materials in many fields of contemporary research. The spectrum of their possible applications ranges from magnetic and magneto-mechanical materials over semiconductors and thermoelectrics to superconductors. An important feature of the Heusler compounds is the possibility of controlling the valence electron concentration by partial substitution of elements. On the other hand, the properties also depend on the degree of ordering of the the crystal structure. In general, Heusler compounds crystallize in the Cu2MnAl-type structure but in many cases certain types of disorder are observed. In this paper a detailed description of the different types of disordered …
Morphology transitions in ZnO nanorods grown by MOCVD
2012
Morphology transitions (nanorods–nanowalls and nanorods–nanotubes-layer) were induced in the growth of ZnO nanostructures by metal organic chemical vapor deposition (MOCVD) on c-sapphire, using helium as carrier gas, and dimethylzinc–triethylamine and nitrous oxide as zinc and oxygen sources, respectively. A systematic study of the influence of the VI/II ratio and precursor flow-rates on the morphology of ZnO nanorod arrays has been carried out, taking advantage of the ability of MOCVD to individually control the precursor partial pressures. Growth mechanisms are discussed to understand the evolution of the nanostructures morphology for different growth conditions. In particular, the influe…
Approximation von extremalflächenstücken (hyperbolischen typs) durch charakteristische räumliche vierecke
1982
We consider solutions z of the Cauchy-problem for hyperbolic Euler-Lagrange equations derived from a general Lagrangian f(x, y, z; zx, zy) in two independent variables x, y. z is supposed to be an extremal of the corresponding variational problem. Visualizing z as a surface in R3 we give a geometric interpretation of Lewy's well-known characteristic approximation scheme for the numerical solution of second order hyperbolic equations by approximating z via a polyhedral construction built up from subunits which consist of two characteristic triangles having one side in common but lying on different planes in R3. Utilizing ideas from Cartan-geometry one can (in an appropriate sense) introduce …
A general 4th-order PDE method to generate Bézier surfaces from the boundary
2006
In this paper we present a method for generating Bezier surfaces from the boundary information based on a general 4th-order PDE. This is a generalisation of our previous work on harmonic and biharmonic Bezier surfaces whereby we studied the Bezier solutions for Laplace and the standard biharmonic equation, respectively. Here we study the Bezier solutions of the Euler-Lagrange equation associated with the most general quadratic functional. We show that there is a large class of fourth-order operators for which Bezier solutions exist and hence we show that such operators can be utilised to generate Bezier surfaces from the boundary information. As part of this work we present a general method…
Monotony Based Imaging in EIT
2010
We consider the problem of determining conductivity anomalies inside a body from voltage‐current measurements on its surface. By combining the monotonicity method of Tamburrino and Rubinacci with the concept of localized potentials, we derive a new imaging method that is capable of reconstructing the exact (outer) shape of the anomalies. We furthermore show that the method can be implemented without solving any non‐homogeneous forward problems and show a first numerical result.
Stefan-Boltzmann Radiation on Non-convex Surfaces
1997
We consider the stationary heat equation for a non-convex body with Stefan–Boltzmann radiation condition on the surface. The main virtue of the resulting problem is non-locality of the boundary condition. Moreover, the problem is non-linear and in the general case also non-coercive and non-monotone. We show that the boundary value problem has a maximum principle. Hence, we can prove the existence of a weak solution assuming the existence of upper and lower solutions. In the two dimensional case or when a part of the radiation can escape the system we obtain coercivity and stronger existence result. © 1997 by B.G. Teubner Stuttgart-John Wiley & Sons, Ltd.
Seifert manifolds admitting partially hyperbolic diffeomorphisms
2017
We characterize which 3-dimensional Seifert manifolds admit transitive partially hyperbolic diffeomorphisms. In particular, a circle bundle over a higher-genus surface admits a transitive partially hyperbolic diffeomorphism if and only if it admits an Anosov flow.
AES and CEMS analysis of the formation of layers on Si steel under thermal treatment in a flux of H2/water vapour
1991
The near surface diffusion and reaction processes in iron-silicon steel (3.1 wt.%Si) during 10 min decarburization in water vapour/hydrogen have been studied. The decarburization temperature has been varied between 506 and 714°C for the fixed partial pressure ratio pH2O/pH2=0.017. An outer layer of SiO2 forms on the surface with its thickness increasing with temperature. From 600°C upwards, the decarburization process is hindered and a cementite layer is formed below the SiO2 layer. The formation of fayalite at the surface has been studied at a fixed decarburization temperature with pH2O/pH2 ranging from 0.017 to 0.49. The scale thickness reduces abruptly just before the ratio pH2O/pH2 nece…
Modeling of PAH elimination by adiabatic steam stripping and intraparticle desorption
2003
The decontamination process of solids loaded with PAH in a pilot plant is modeled. This process is separated into two main stages: fast steam stripping at the entrance of the separation tube and the subsequent slow desorption of PAH from the interior of the soil particles. The stripping process also occurs in two stages: fast diffusion controlled saturation of the partial pressures followed by the heat transfer controlled evaporation. The phase diagram of PAH/water is constructed using both the microscopic model and empirical relationships for systems with wide miscibility gaps. The numerical basis for the calculations describing desorption from the soil particles is discussed. The model fo…
Performance of EasyBreath® Decathlon Snorkeling mask for Delivering Continuous Positive Airway Pressure
2020
ABSTRACTBackgroundDuring the COVID-19 pandemic, the need for noninvasive respiratory support devices has dramatically increased, sometimes exceeding hospital capacity. The full-face Decathlon snorkeling mask, EasyBreath® (EB® mask), has been adapted to deliver continuous positive airway pressure (CPAP) as an emergency respiratory interface. We aimed to assess the performance of this modified EB® mask.MethodsCPAP set at 5, 10, and 15 cmH2O was delivered to 10 healthy volunteers with a high-flow system generator set at 40, 80, and 120 L min-1 and with a turbine-driven ventilator during both spontaneous and loaded (resistor) breathing. Inspiratory CO2 partial pressure (PiCO2), pressure inside …