Characterisation of the microporous structure of activated carbons using immersion calorimetry

A method of determining the main parameters of the micropore structure of activated carbons is proposed, based on Dubinin's theory of micropore filling, but using data from immersion calorimetry and water vapor adsorption at different relative pressures p/p_s.     

Heat and mass transfer in packed beds—IV: Use of weighted moments to determine axial dispersion coefficients

The method of weighted moments is analysed on the basis of measured axial dispersion in a methanehydrogen mixture flowing through a bed of glass beads at various velocities. The optimum value of the Laplace parameter S is chosen as the one giving the minimum deviation between experiment and model in the integrand of the second weighted moment. The corresponding axial dispersion coefficients are lower than those determined with ordinary moments, and agree very closely with the best-fit values in the time domain. An equation proposed by Anderssen and White based on other considerations is shown to give a relatively good approximation of the optimum value of S. With the aid of this near-optimum S, calculating time for weighted moments can be shorter than for curve fitting in the time domain.     

On the Monte Carlo simulation of digital communication systems in Gaussian noise

We consider the general problem of the simulation of highly reliable systems operating in the presence of Gaussian noise. Our methodology uses importance sampling which has been shown to be a particularly effective method in the general discipline of rare-event simulation. The methods we propose are optimal in a certain sense, i.e., they are efficient. We also give a new class of simulation distributions that are universally efficient in the sense that they depend only on a single scalar parameter, regardless of the dimensionality of the underlying system or of the error sets to be simulated.     

Large-scale powder mixer simulations using massively parallel GPUarchitectures

Granular flows are extremely important for the pharmaceutical and chemical industry, as well as for other scientific areas. Thus, the understanding of the impact of particle size and related effects on the mean, as well as on the fluctuating flow field, in granular flows is critical for design and optimization of powder processing operations.We use a specialized simulation tool written in C and CUDA (Compute Unified Device Architecture), a massive parallelization technique which runs on the Graphics Processing Unit (GPU). We focus on both, a new implementation approach using CUDA/GPU, as well as on the flow fields and mixing properties obtained in the million-particlerange.We show that using CUDA and GPUs, we are able to simulate granular flows involving several millions of particles significantly faster than using currently available software. Our simulation results are intended as a basis for enhanced DEM simulations, where fluid spraying, wetting and fluid spreading inside the powder bed is considered.     

Force distribution analysis in loaded planar disc systems by means of FEM

This paper presents results of mechanical analyses of force distributions in three geometrically different loaded planar disc systems. For the calculations the disc systems are replaced by mechanically equivalent beam systems, and FEM then yields the contact forces in a simple way. There is a big influence of the geometrical arrangement of discs on force transmission and of disc diameters on the magnitudes of contact forces. The statistical analyses lead to a new probability distribution for the contact forces, namely the distribution of the absolute value of a Gaussian random variable. Received: 13 December 2001     

Comparing the personal lives of psychotherapists and research psychologists.

Being a psychotherapist is a complex challenge. Research has suggested that therapists are changed by their work, but it has not been clear whether these changes are the same for research psychologists and practitioners. 276 representatives of these 2 groups were surveyed. Although therapists reported more anxiety, depression, and emotional exhaustion than did researchers, they were also more satisfied with their lives and more likely than researchers to feel that their work had influenced them in positive ways. Therapists' work as practitioners may be emotionally stressful but it may also enrich their lives. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of the Classifying Efficiency of Spiral Jet Mills by Investigating the Flow Conditions and the Grinding Performance

The achievable grinding fineness of spiral jet mills does not only depend on the comminution efficiency in the region of the nozzle jets but is also significantly affected by the separation efficiency in the region of the product outlet. Therefore, the aim of this study is to investigate the influences of the product outlet diameter and different particle trap rings on the flow conditions and the grinding performance, optimizing the classifying efficiency of spiral jet mills. The velocity fields analyzed by particle image velocimetry and the experimental grinding results show that the classification process can be optimized by both reducing the product outlet diameter and installing a particle trap ring.