Digital predictions of complex cylinder packed columns

A digital computational approach has been developed to simulate realistic structures of packed beds. The underlying principle of the method is digitisation of the particles and packing space, enabling the generation of realistic structures. Previous publications [Caulkin, R., Fairweather, M., Jia, X., Gopinathan, N., & Williams, R.A. (2006). An investigation of packed columns using a digital packing algorithm. Computers & Chemical Engineering, 30, 1178–1188; Caulkin, R., Ahmad, A., Fairweather, M., Jia, X., & Williams, R. A. (2007). An investigation of sphere packed shell-side columns using a digital packing algorithm. Computers & Chemical Engineering, 31, 1715–1724] have demonstrated the ability of the code in predicting the packing of spheres. For cylindrical particles, however, the original, random walk-based code proved less effective at predicting bed structure. In response to this, the algorithm has been modified to make use of collisions to guide particle movement in a way which does not sacrifice the advantage of simulation speed. Results of both the original and modified code are presented, with bulk and local voidage values compared with data derived by experimental methods. The results demonstrate that collisions and their impact on packing structure cannot be disregarded if realistic packing structures are to be obtained

Do consumers really care about corporate responsibility? Highlighting the attitude-behaviour gap

According to the press at the turn of the year 1999—2000, a good corporate reputation for responsible marketing is a key element in business success. One justification for this is the assumption that consumers are interested in how companies behave and this has an influence upon their consumption behaviour. There is also the suggestion that a financial pay-off is to be gained from good behaviour. Conflicting reports in previous research cast doubt upon the reliability of these assumptions, and there are few studies which unequivocally support positive consumer purchasing in return for responsible marketing. This paper reviews current opinion and evidence in relation to the growing interest in corporate reputation, and reports findings from focus group research which casts doubt upon the efficacy of corporate reputation in influencing positive consumer purchase behaviour

Creative Requirement: A Neglected Construct in the Study of Employee Creativity?

We identify the creative requirement of a job as a neglected predictor of employee creativity and propose that it may account for relationships between traditional work factors and creativity. As such, it may represent a more effective means of increasing creativity than changes in job design. Using structural equation modeling, we tested this model against four competing models, using a sample of 1083 health service employees. Creative requirement was found to account for much of the variance by fully mediating the effects of supportive leadership and role requirements and partially mediating those of empowerment and time demands. We conclude that creative requirement is an important proximal determinant of employee creativity and a potentially significant intervention

Validation of DigiPac Simulations of packed columns using x-ray microtomography

peer reviewe

Simulations of structures in packed columns and validation by X-ray tomography

Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray computerized tomography (CT). Two modified versions of what was previously a purely geometrical, digitally based packing algorithm were implemented. Both are aimed at incorporating the effects of particle interaction forces, one utilizing the distinct element method (DigiDEM) and the other an intermediate solution (collision-guided packing or DigiCGP). This article summarizes the models and the simulations performed using these two modified versions of DigiPac and, for model validation purposes, compares the predicted results with the corresponding X-ray tomographic scans of packed columns, in terms of bulk density, local packing density profiles, and pellet orientation distributions. For packed beds of relatively large and identical pellets, the simulation results indicate that particle-particle and particle-wall interactions cannot be ignored if realistic packing structures are to be obtained by simulation and even a simplistic treatment of these interactions can produce significantly more realistic packing structure than none at all. © 2009 American Chemical Society.R. Caulkin, X. Jia, C. Xu, M. Fairweather, R. A. Williams, H. Stitt, M. Nijemeisland, S. Aferka, M. Crine, A. Leonard, D. Toye and P. Marcho