Steady and transient mass transport phenomena within an inverted, stagnation-flow, cold-wall CVD reactor were investigated by observing the concentration of a tracer species (CH4) with in situ Raman spectroscopy. The transient studies revealed that the use of matched reactor inlet velocities is crucial to minimize recirculating flow patterns and that the magnitude of the gas velocity is also im...

We report on simulations of two-dimensional turbulence in the inverse energy cascade regime. Focusing on the statistics of Lagrangian tracer particles, scaling behavior of the probability density functions of velocity fluctuations is investigated. The results are compared to the three-dimensional case. In particular an analysis in terms of compensated cumulants reveals the transition from a str...

The generic mechanisms of anomalous transport in porous media are investigated by computer simulations of two-dimensional model systems. In order to bridge the gap between the strongly idealized Lorentz model and realistic models of porous media, two models of increasing complexity are considered: a cherry-pit model with hard-core correlations as well as a soft-potential model. An ideal gas of ...

We describe a method for computing a continuous time estimate of dynamic changes in tracer density using list mode PET data. The tracer density in each voxel is modeled as an inhomogeneous Poisson process whose rate function can be represented using a cubic B-spline basis. An estimate of these rate functions is obtained by maximizing the likelihood of the arrival times of each detected photon p...

In the Tabas coal preparation plant (SE Iran), -50 + 6 mm raw coal was treated in a 700 mm two-stage two-density Tri-Flo dynamic dense medium separator. In order to study the circuit performance and to evaluate the separator efficiency, 32 mm cubic density tracers were used in the range of 1.28-2.1 g/cm3 and under different operational conditions. The performance of Tri-Flo was evaluated in a r...

A high-resolution finite element method is developed for numerical simulation of Z-pinch-like implosions using a phenomenological model for the magnetic drive source term. The momentum and energy equations of the Euler system are extended by adding radial body forces proportional to the concentration of a scalar tracer field. The evolution of the tracer is governed by an additional transport eq...

We introduce the tracer mass estimator. This is a new and simple way to estimate the enclosed mass from the projected positions and line of sight velocities of a tracer population (such as globular clusters, halo stars and planetary nebulae). Like the projected mass estimator, it works by averaging (projected distance)× (radial velocity)/G over the sample. However, it applies to the commonest c...

To enable the mechanistic description of mixing larger particles in gas-fluidized beds models (e.g. fuel combustors), knowledge about rheology bed emulsion is required. Here, it crucial to determine drag on large fuel-alike particles. This work presents experimental fate 13 different solid spheres falling or rising through a air and glass beads at minimum fluidization. The trajectories tracer a...

I review 1 recent progress in the study of the large-scale structure of the Universe through the distribution of clusters of galaxies, concentrating on new results using X-ray selected samples. After discussing the importance of understanding the properties of the tracers used to map structure and their relation to the underlying mass, I elaborate on the advantages and disadvantages of clusters...