Experiences of misfit as cues for sensemaking of ERPs

The adoption of computer-based enterprise resource planning systems (ERPs) has become an important feature of large organisations in both the public and private sectors. Successfully embedding ERP systems in organisational structures does, however, pose a significant array of technical and social (human) challenges. Chief among these is ensuring that ERP users successfully adapt to new/changed work processes and tasks post-adoption. In this study Karl Weick's theory of Sensemaking is adopted to investigate the process by which users develop the meaningful understandings of ERPs. It is proposed that experiences of misfit, that result from user ignorance or organisation-artefact misalignment, act as triggers for sensemaking. Based on an integrated interpretive framework a case study of a South African Metropolitan Municipality is used to analyse 34 experiences of misfit and their consequences. Findings suggest that experiences of misfit trigger various types of response strategies during which users’ understanding of and beliefs about ERP technology are updated

Ouaga 2007 : habiter, peupler, socialiser par les mobilités

Ce rapport dresse un panorama des mobilités et migrations qui traversent, forment et dynamisent Ouagadougou en 2007, date de l’enquête dont il présente les résultats. Il engage une observation des diverses mobilités formant la ville, observation qui sera actualisée en 2009 dans le cadre d’un projet plus large incluant d’autres capitales sahéliennes (Bamako, Niamey), avec la promesse de comparaisons instructives sur les évolutions urbaines de la sous-région. Dans cette étude, les migrations internationales sont centrales, mais elles sont replacées aux côtés des mouvements internes et des pratiques de multirésidence ou des migrations temporaires. En arrière-plan de l’analyse de ces mouvements, analyse déclinée selon l’âge, le sexe, l’éducation et le travail des individus, s’impose un questionnement sur les logiques de l’installation et du peuplement en ville. Dès lors, les migrations apparaissent comme une composante de la vulnérabilité urbaine, du caractère informel du travail. En effet, l’intensité des flux migratoires qui traversent et font la ville infléchit sa composition sociale et spatiale et ainsi son futur

A Bayesian approach for inferring the dynamics of partially observed endemic infectious diseases from space-time-genetic data

We describe a statistical framework for reconstructing the sequence of transmission events between observed cases of an endemic infectious disease using genetic, temporal and spatial information. Previous approaches to reconstructing transmission trees have assumed all infections in the study area originated from a single introduction and that a large fraction of cases were observed. There are as yet no approaches appropriate for endemic situations in which a disease is already well established in a host population and in which there may be multiple origins of infection, or that can enumerate unobserved infections missing from the sample. Our proposed framework addresses these shortcomings, enabling reconstruction of partially observed transmission trees and estimating the number of cases missing from the sample. Analyses of simulated datasets show the method to be accurate in identifying direct transmissions, while introductions and transmissions via one or more unsampled intermediate cases could be identified at high to moderate levels of case detection. When applied to partial genome sequences of rabies virus sampled from an endemic region of South Africa, our method reveals several distinct transmission cycles with little contact between them, and direct transmission over long distances suggesting significant anthropogenic influence in the movement of infected dogs

Instance-specific linear relaxations of semidefinite optimization problems

We present a simple yet flexible systematic way to significantly improve linear relaxations of semidefinite optimization programs (SDPs) using instance-specific information. We get inspiration for our approach by studying the celebrated SDP relaxation for max cut (GW) due to Poljak and Rendl [1995] and analyzed by Goemans and Williamson [1995]. Using the instance at hand, we provide a pair of closely related compact linear programs that sandwich the optimal value of the GW semidefinite program. The instance specific information allows us to trivially avoid hardness of approximation results of semidefinite programs using linear ones, such as Braun et al. [2015] and Kothari et al. [2021]. We give sufficient conditions that guarantee that the optimal value of both our programs match the optimal value of the semidefinite relaxation. We use these conditions to prove that our two bounds give the same value as the GW SDP for max cut on distance-regular graphs, and in particular, strongly regular graphs such as cycles and the Petersen graph. Further, we show that the approximation of the upper bounding problem is strictly better than the eigenvalue bounds of Mohar and Poljak [1990], Alon and Sudakov [2000] for max cut. To the best of our knowledge, no previously proposed linear program proposed for max cut has this guarantee. We extensively test our methodology on synthetic and real graphs, and show how our ideas perform in practice. Even though our methodology is inspired by the SDP relaxation for max cut, we show experimentally that our ideas can be applied successfully to obtain good solutions to other computationally hard SDPs such as sparse PCA and the Lovasz Theta number

Evaluation and performance enhancement of cooling tower spray zones

Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The performance of wet cooling towers can be improved by installing spray nozzles that distribute the cooling water uniformly onto the fill whilst operating at a low pressure head. In this thesis, three commercial spray nozzles are experimentally evaluated in terms of flow and pressure loss characteristics as well as water distribution patterns. The results of the evaluation process highlight the need for spray nozzles with enhanced performance characteristics. The theory required to implement the results of the evaluation process in the design of a cooling tower is presented and discussed. A systematic approach to enhance the performance of a spray nozzle through minor alterations is applied to one of the commercial spray nozzles that was evaluated. The fluid dynamics of an orifice nozzle, such as the effect of a change in pressure head, spray angle, spray height, orifice diameter and wall thickness on drop diameter and spray distance, is experimentally investigated and a model with which a spray nozzle can be designed is finally presented. Two prototype spray nozzles show that it is possible to enhance the performance of spray nozzles and thus wet cooling towers by means of the methods presented.AFRIKAANSE OPSOMMING: Die werkverrigting van natkoeltorings kan verbeter word deur sproeiers te installeer wat die verkoelingswater uniform versprei op die pakking teen 'n lae pomp drukhoogte. In hierdie tesis word drie kommersiële sproeiers eksperimenteel geëvalueer in terme van vloei en drukverlies eienskappe sowel as water verdelings patrone. Die resultate van die evaluasie proses beklemtoon die behoefte aan sproeiers met verbeterde werkverrigtingseienskappe. Die teorie wat benodig word om die resultate van die evaluasie proses te implementeer in die ontwerp van 'n natkoeltoring word bespreek. 'n Stelselmatige benadering om die werkverrigtings van 'n sproeier te verhoog deur klein veranderinge aan die ontwerp aan te bring, word toegepas op een van die sproeiers wat getoets is. Die vloeidinamika van 'n plaatmondstuk, soos die effek van 'n verandering in drukhoogte, sproeihoek, sproeihoogte, gatdiameter en wanddikte op druppel diameter en sproeiafstand, is eksperimenteel ondersoek en 'n model word aangebied waarmee 'n sproeier ontwerp kan word. Twee prototipe sproeiers wys dat dit moontlik is om die werkverrigting van sproeiers, en dus ook natkoeltorings, te verbeter deur die metodes wat in die tesis aangebied word, toe te pas

Simultaneous-FETI and Block-FETI: robust domain decomposition with multiple search directions.

International audienceDomain Decomposition methods often exhibit very poor performance when applied to engineering problems with large heterogeneities. In particular for heterogeneities along domain interfaces the iterative techniques to solve the interface problem are lacking an efficient preconditioner. Recently a robust approach, named FETI-Geneo, was proposed where troublesome modes are precomputed and deflated from the interface problem. The cost of the FETI-Geneo is however high. We propose in this paper techniques that share similar ideas with FETI-Geneo but where no pre-processing is needed and that can be easily and efficiently implemented as an alternative to standard Domain Decomposition methods. In the block iterative approaches presented in this paper, the search space at every iteration on the interface problem contains as many directions as there are domains in the decomposition. Those search directions originate either from the domain-wise preconditioner (in the Simultaneous FETI method) or from the block structure of the right-hand side of the interface problem (Block FETI). We show on 2D structural examples that both methods are robust and provide good convergence in the presence of high heterogeneities, even when the interface is jagged or when the domains have a bad aspect ratio. The Simultaneous FETI was also efficiently implemented in an optimized parallel code and exhibited excellent performance compared to the regular FETI method

Boundary feedback controller over a bluff body for prescribed drag and lift coefficients

This paper presents an improved boundary feedback controller for the two and three-dimensional Navier-Stokes equations, in a bounded domain Ω, for prescribed drag and lift coefficients. In order to determine the feedback control law, we consider an extended system coupling the equations governing the Navier-Stokes problem with an equation satisfied by the control on the bluff body, which is a part of the domain boundary. By using the Faedo-Galerkin method and a priori estimation techniques, a stabilizing boundary control is built. This control law ensures the stability of the controlled discrete system. A compactness result then allows us to pass to the limit in the non linear system satisfied by the approximated solutions