Process for the preparation of catalytically active cross-linked metal silicate

Highly active and selective hydroisomerization catalysts are prepared by heating to 300 DEG -450 DEG C. at subatmospheric pressure, a mixture of nickel synthetic mica montmorillonite (Ni-SMM) with a hydroxy aluminum polymeric solution. The resulting pillared Ni-SMM catalyst, preferably Pd-loaded, is especially useful in hydroisomerizing C4-C7 paraffins

A comment on free-fermion conditions for lattice models in two and more dimensions

We analyze free-fermion conditions on vertex models. We show --by examining examples of vertex models on square, triangular, and cubic lattices-- how they amount to degeneration conditions for known symmetries of the Boltzmann weights, and propose a general scheme for such a process in two and more dimensions.Comment: 12 pages, plain Late

Random Matrix Theory and Classical Statistical Mechanics. I. Vertex Models

A connection between integrability properties and general statistical properties of the spectra of symmetric transfer matrices of the asymmetric eight-vertex model is studied using random matrix theory (eigenvalue spacing distribution and spectral rigidity). For Yang-Baxter integrable cases, including free-fermion solutions, we have found a Poissonian behavior, whereas level repulsion close to the Wigner distribution is found for non-integrable models. For the asymmetric eight-vertex model, however, the level repulsion can also disappearand the Poisson distribution be recovered on (non Yang--Baxter integrable) algebraic varieties, the so-called disorder varieties. We also present an infinite set of algebraic varieties which are stable under the action of an infinite discrete symmetry group of the parameter space. These varieties are possible loci for free parafermions. Using our numerical criterion we have tested the generic calculability of the model on these algebraic varieties.Comment: 25 pages, 7 PostScript Figure

Effective water storage as flood protection; the Rijnstrangen study case

Climate change is expected to cause higher discharge levels in the river Rhine at the Dutch-German border. In this study group project that was commissioned by Rijkswaterstaat , we investigate the possibility of flooding the Rijnstrangen area as a protective measure. We identify three subproblems. We first analyze the data recorded by Rijkswaterstaat and estimate the likelihood and the duration of extremely large discharges at the German border into the river. Next, we investigate how a change in discharge levels affects the water height in the first 35 kilometer section in the Netherlands. Finally we study the design of weirs and floodgates to allow diverting a sufficiently large amount of water flow from the river into the retention area. Our statistical analysis shows that an extreme discharge level is expected to occur once every 1250 years and to last for about three and a half days. Our numerical flow model shows the water height reaches equilibrium on a time scale that is much smaller than the one on which flooding occurs. The flow can thus be considered quasi-stationary. Passive weirs finally are shown to be too long to be feasible. Actively controlled floodgates are therefore recommended.Delft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc

Nonlinear cochlear dynamics

In this report we examine a model for human hearing. The unknown parameters in the model are estimated using experimental data and standard optimisation methods as described in the text. Additionally, we suggest possible improvements to the model as well as proposing a method to use the current model in locating which frequencies are aected in a damaged ear. Keywords: cochlear model, delay dierential equation, parameter es-timation, hearing los