Neumann and Bargmann systems associated with an extension of the coupled KdV hierarchy

An eigenvalue problem with a reference function and the corresponding hierarchy of nonlinear evolution equations are proposed. The bi-Hamiltonian structure of the hierarchy is established by using the trace identity. The isospectral problem is nonlinearized as to be finite-dimensional completely integrable systems in Liouville sense under Neumann and Bargmann constraints

Modelling and analysis of CVD processes for ceramic membrane preparation

A mathematical model is presented that describes the modified chemical vapour deposition (CVD) process (which takes place in advance of the electrochemical vapour deposition (EVD) process) to deposit ZrO2 inside porous media for the preparation and modification of ceramic membranes. The isobaric model takes into account intrapore Knudsen diffusion of ZrCl4 and H2O, which enter the membrane from opposite sides, and Langmuir-Hinshelwood reaction of the solid product ZrO2 on the internal pore wall. The processes occurring in one single pore are investigated, and the change in pore geometry during deposition is taken into account. Based upon this model, the deposition profile is studied. The model fits reasonably well with experimental results

Bereiding en karakterisatie van α'-sialon

The article summarizes work of a Ph.D. thesis defended at the Eindhoven University of Technology. It describes research of the preparation and properties of a'-sialons and a'-ß'composite materials. X-ray diffraction and dilatometry were used to investigate the reaction sequence and densification under nitrogen pressures up to 100 bar and temperatures up to 1900°C. Hardness and bendingstrength were measured as a function of composition and microstructure

Neutron diffraction study of yttrium α'-sialon

The structure of yttrium a'-Sialon ceramic of compn. Y0.5Si9.75Al2.25N15.25O0.75 was examd. by powd. neutron diffraction and Rietfeld refinement of the data. [on SciFinder (R)

Bereiding en karakterisatie van α'-sialon

The article summarizes work of a Ph.D. thesis defended at the Eindhoven University of Technology. It describes research of the preparation and properties of a'-sialons and a'-ß'composite materials. X-ray diffraction and dilatometry were used to investigate the reaction sequence and densification under nitrogen pressures up to 100 bar and temperatures up to 1900°C. Hardness and bendingstrength were measured as a function of composition and microstructure

Microstructural development, electrical properties and oxygen permeation of zirconia-palladium composites

Yttria-stabilized cubic zirconia (YSZ)-palladium dual phase composites have been investigated. The percolative composite containing 40 vol% Pd (ZYPd40) showed a much larger oxygen permeability than that of the non-percolative composite containing 30 vol% Pd (ZYPd30). For a 2.0 mm thick percolative composite, an oxygen flux of 4.3 × 10−8 mol/cm2/s was measured at 1100 °C with oxygen partial pressures at the feed and permeate sides being 0.209 and 0.014 atm, respectively. This value is two orders of magnitude larger than that observed for a 2.0 mm thick non-percolative composite at the same temperature with the oxygen partial pressures at the feed and permeate sides being 0.209 and 1.5 × 10−4 atm, respectively. From the dependence of the oxygen permeation on the temperature and on the oxygen partial pressures, it was concluded that the transport of the oxygen ions through the YSZ phase in the percolative system was the rate limiting step

Wear and friction of Y-TZP spheres reciprocating against various Sialon plates

The friction and wear characteristics of various Y2O3-stabilized tetragonal ZrO2 polycrystal (Y-TZP)-Sialon sliding systems were examd. These systems consisted of a Y-TZP sphere reciprocating against various Sialon plates. The Sialons differed in phase content and compn. They range from a-Sialons to b-Sialons and include a-b composites. The length of the wear tracks was 10 mm, the loads used were 2 and 8 N, the frequencies 1, 4 and 8 Hz and the humidity was controlled by flushing with dry nitrogen. The tests were continued for 8, 24 and 72 h at room temp. The total vertical displacement and the friction coeff. were measured continuously and sampled. Various addnl. measurements were performed after each test and the worn surfaces were obsd. microscopically. It was concluded that the a-b composites show less wear than the single-phase a- and b-Sialons. It was also concluded that the amt. of wear increases approx. linearly with increasing load and increases significantly more than linearly with increasing frequency. A wear mechanism was derived incorporating the measured data and the observations. [on SciFinder (R)

Mid-infrared Suspended Waveguide Platform and Building Blocks

In this work we present our recent progress in the development of a platform for the mid-infrared wavelength range, based on suspended silicon waveguide with subwavelength metamaterial cladding. The platform has some intrinsic advantages, which make it a very promising candidate for sensing applications in the fingerprint region. Specifically, it can cover the full transparency window of silicon (up to a wavelength of 8 μm), only requires one lithographic etch-step and can be designed for strong light-matter interaction. Design rules, practical aspects of the fabrication process and experimental results of a complete set of elemental building blocks operating at two very different wavelengths, 3.8 μm and 7.67 μm, will be discussed. Propagation losses as low as 0.82 dB/cm at λo=3.8 μm and 3.1 dB/cm at λo=7.67 μm are attained, for the interconnecting waveguides.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech