In the first part of this work, the electrical conductivity of vanadium phosphorous oxide (VPO) catalyst was investigated by means of the 2-probe EIS method. The VPO showed an extremely low conductivity at low oxygen partial pressure, which is the prevailing condition in the anodic compartment in an electrochemical membrane reactor (EMR). In the second part of this study, fresh as well as VPO catalyst already used in an EMR were characterised with XRD, XPS and temperature programmed oxidation (TPO). The XRD measurements revealed an unchanged bulk phase structure after operation in the EMR. Significant differences in the average oxidation states of vanadium in the catalyst layer in the EMR were determined via XPS, where the catalyst surface facing the electrolyte membrane was more oxidised than the surface facing the anodic gas compartment. The lowered uptake and release of oxygen was observed in TPO experiments for the catalyst used in the EMR.

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Bulk and surface properties of a VPO catalyst used in an electrochemical membrane reactor : conductivity-, XRD-, TPO- and XPS-study

This paper introduces a new modular software approach combining symbolical and numerical methods for the simulation of the dynamics of mechanical systems. It is based on an exact, noniterative object-oriented algorithm, which is applicable to mechanisms with any joint type and any topology, including branches and kinematic loops. The simulation of big well-partitioned systems has complexity O(N), where N is the total number of simulated bodies. A new design software Virtual System Designer (VSD) integrates this method with the three-dimensional computer aided design tool Autodesk Inventor, which minimizes the cost of the development of models and the training of design engineers. The most time-expensive routine of the simulation process in VSD is the calculation of the accelerations of each body, which needs to find the roots of matrix equations. Accounting for the sparsity of matrices can significantly improve the numerical efficiency of the routine. The preprocessing module, developed using Maple software, performs the symbolic simplification of the matrix multiplication's and QR decomposition's procedures. The new coordinate projection method is demonstrated. The results of the simulation of the dynamics of a double insulator chain example show the method's stability and effectiveness.

A New Software Approach for the Simulation of Multibody Dynamics

This paper presents a recursive algorithm for calculating the forward dynamics of general rigid-body systems using a subsystem approach. It is an exact, non-iterative algorithm that is applicable to mechanisms with any joint type and any topology, including branches and kinematic loops. As stabilization is done also in a modular way, the method is well suited for distributed processing. The calculation of accelerations has O(log(n)) time complexity on O(n) processors, that is comparable with the fastest available parallel algorithms. The method was implemented in an object-oriented simulation tool, which can translate models from Autodesk Inventor.

Otto-von-Guericke-University Magdeburg

Papers

Modular forward dynamic simulation of constrained mechanical systems