Regime mapping and the role of the intermediate region in wall-coated microreactors

Operation of a wall-coated microreactor can occur in several mass transfer-reaction regimes. We define these regimes analytically in several planes of a multi-parametric map, taking into account the different degrees of concentration profile development, as well as the influence of non-unity orders of reaction and reactant inhibition in the kinetic law. It was found that the regions where conversion can be calculated from simplified mass transfer models are not discriminated by common results for entrance-length. We also illustrate the trade-offs that exist across this operating map concerning the catalyst design (costs associated with loading and volume) and overall system performance (evaluated in terms of reactant conversion, flow efficiency and microreactor effectiveness). It is shown that under certain conditions, the existence of moderate mass transfer resistance can be advantageous (even if internal limitations cannot be avoided), clarifying the role of the intermediate transport-reaction region

Constrained set-up of the tGAP structure for progressive vector data transfer

A promising approach to submit a vector map from a server to a mobile client is to send a coarse representation first, which then is incrementally refined. We consider the problem of defining a sequence of such increments for areas of different land-cover classes in a planar partition. In order to submit well-generalised datasets, we propose a method of two stages: First, we create a generalised representation from a detailed dataset, using an optimisation approach that satisfies certain cartographic constraints. Second, we define a sequence of basic merge and simplification operations that transforms the most detailed dataset gradually into the generalised dataset. The obtained sequence of gradual transformations is stored without geometrical redundancy in a structure that builds up on the previously developed tGAP (topological Generalised Area Partitioning) structure. This structure and the algorithm for intermediate levels of detail (LoD) have been implemented in an object-relational database and tested for land-cover data from the official German topographic dataset ATKIS at scale 1:50 000 to the target scale 1:250 000. Results of these tests allow us to conclude that the data at lowest LoD and at intermediate LoDs is well generalised. Applying specialised heuristics the applied optimisation method copes with large datasets; the tGAP structure allows users to efficiently query and retrieve a dataset at a specified LoD. Data are sent progressively from the server to the client: First a coarse representation is sent, which is refined until the requested LoD is reached

Exploring Uncertainty in Geodemographics with Interactive Graphics

Geodemographic classifiers characterise populations by categorising geographical areas according to the demographic and lifestyle characteristics of those who live within them. The dimension-reducing quality of such classifiers provides a simple and effective means of characterising population through a manageable set of categories, but inevitably hides heterogeneity, which varies within and between the demographic categories and geographical areas, sometimes systematically. This may have implications for their use, which is widespread in government and commerce for planning, marketing and related activities. We use novel interactive graphics to delve into OAC – a free and open geodemographic classifier that classifies the UK population in over 200,000 small geographical areas into 7 super-groups, 21 groups and 52 sub-groups. Our graphics provide access to the original 41 demographic variables used in the classification and the uncertainty associated with the classification of each geographical area on-demand. It also supports comparison geographically and by category. This serves the dual purpose of helping understand the classifier itself leading to its more informed use and providing a more comprehensive view of population in a comprehensible manner. We assess the impact of these interactive graphics on experienced OAC users who explored the details of the classification, its uncertainty and the nature of between – and within – class variation and then reflect on their experiences. Visualization of the complexities and subtleties of the classification proved to be a thought-provoking exercise both confirming and challenging users’ understanding of population, the OAC classifier and the way it is used in their organisations. Users identified three contexts for which the techniques were deemed useful in the context of local government, confirming the validity of the proposed methods

Analysis of a duffing oscillator that exhibits hysteresis with varying excitation frequency and amplitude

Hysteresis, or jump phenomenon, are a common and severe nonlinear behaviour associated with the Duffing oscillator and the multi-valued properties of the response solution. Jump phenomenon can be induced by either varying the amplitude or the frequency of excitation. In this paper a new time and frequency domain analysis is applied to this class of system based on the response curve and the response spectrum map