The imperfect hiding : some introductory concepts and preliminary issues on modularity

In this work we present a critical assessment of some problems and open questions on the debated notion of modularity. Modularity is greatly in fashion nowadays, being often proposed as the new approach to complex artefact production that enables to combine fast innovation pace, enhanced product variety and reduced need for co-ordination. In line with recent critical assessments of the managerial literature on modularity, we sustain that modularity is only one among several arrangements to cope with the complexity inherent in most high-technology artefact production, and by no means the best one. We first discuss relations between modularity and the broader (and much older within economics) notion of division of labour. Then we sustain that a modular approach to labour division aimed at eliminating technological interdependencies between components or phases of a complex production process may have, as a by-product, the creation of other types of interdependencies which may subsequently result in inefficiencies of various types. Hence, the choice of a modular design strategy implies the resolution of various tradeoffs. Depending on how such tradeoffs are solved, different organisational arrangements may be created to cope with ‘residual’ interdependencies. Hence, there is no need to postulate a perfect isomorphism, as some recent literature has proposed, between modularity at the product level and modularity at the organisational level

The imperfect hiding: Some introductory concepts and preliminary issues on modularity.

In this work we present a critical assessment of some problems and open questions on the debated notion of modularity. Modularity is greatly in fashion nowadays, being often proposed as the new approach to complex artefact production that enables to combine fast innovation pace, enhanced product variety and reduced need for co-ordination. In line with recent critical assessments of the managerial literature on modularity, we sustain that modularity is only one among several arrangements to cope with the complexity inherent in most high-technology artefact production, and by no means the best one. We first discuss relations between modularity and the broader (and much older within economics) notion of division of labour. Then we sustain that a modular approach to labour division aimed at eliminating technological interdependencies between components or phases of a complex production process may have, as a by-product, the creation of other types of interdependencies which may subsequently result in inefficiencies of various types. Hence, the choice of a modular design strategy implies the resolution of various tradeoffs. Depending on how such tradeoffs are solved, different organisational arrangements may be created to cope with 'residual' interdependencies. Hence, there is no need to postulate a perfect isomorphism, as some recent literature has proposed, between modularity at the product level and modularity at the organisational level.

Robust watermarking for magnetic resonance images with automatic region of interest detection

Medical image watermarking requires special considerations compared to ordinary watermarking methods. The first issue is the detection of an important area of the image called the Region of Interest (ROI) prior to starting the watermarking process. Most existing ROI detection procedures use manual-based methods, while in automated methods the robustness against intentional or unintentional attacks has not been considered extensively. The second issue is the robustness of the embedded watermark against different attacks. A common drawback of existing watermarking methods is their weakness against salt and pepper noise. The research carried out in this thesis addresses these issues of having automatic ROI detection for magnetic resonance images that are robust against attacks particularly the salt and pepper noise and designing a new watermarking method that can withstand high density salt and pepper noise. In the ROI detection part, combinations of several algorithms such as morphological reconstruction, adaptive thresholding and labelling are utilized. The noise-filtering algorithm and window size correction block are then introduced for further enhancement. The performance of the proposed ROI detection is evaluated by computing the Comparative Accuracy (CA). In the watermarking part, a combination of spatial method, channel coding and noise filtering schemes are used to increase the robustness against salt and pepper noise. The quality of watermarked image is evaluated using Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM), and the accuracy of the extracted watermark is assessed in terms of Bit Error Rate (BER). Based on experiments, the CA under eight different attacks (speckle noise, average filter, median filter, Wiener filter, Gaussian filter, sharpening filter, motion, and salt and pepper noise) is between 97.8% and 100%. The CA under different densities of salt and pepper noise (10%-90%) is in the range of 75.13% to 98.99%. In the watermarking part, the performance of the proposed method under different densities of salt and pepper noise measured by total PSNR, ROI PSNR, total SSIM and ROI SSIM has improved in the ranges of 3.48-23.03 (dB), 3.5-23.05 (dB), 0-0.4620 and 0-0.5335 to 21.75-42.08 (dB), 20.55-40.83 (dB), 0.5775-0.8874 and 0.4104-0.9742 respectively. In addition, the BER is reduced to the range of 0.02% to 41.7%. To conclude, the proposed method has managed to significantly improve the performance of existing medical image watermarking methods

Challenging the Computational Metaphor: Implications for How We Think

This paper explores the role of the traditional computational metaphor in our thinking as computer scientists, its influence on epistemological styles, and its implications for our understanding of cognition. It proposes to replace the conventional metaphor--a sequence of steps--with the notion of a community of interacting entities, and examines the ramifications of such a shift on these various ways in which we think

Open Source Software Production, Spontaneous Input, and Organizational Learning

This work shows that the modular organization of voluntary Open Source Software (OSS) production, whereby programmers supply effort of their accord, capitalizes more on division than on specialization of labor. This is so because voluntary OSS production is characterized by an organizational learning process that dominates the individual one. Organizational learning reveals production choices that would otherwise remain unknown, thereby increasing productivity and indirectly reinforcing incentives to undertake collective problem solving.Division of Labor; Mistake-ridden Learning; Modularity; Open Source Software; Self-selection; Voluntary Production

An empirical study of software design practices

Software engineers have developed a large body of software design theory and folklore, much of which was never validated. The results of an empirical study of software design practices in one specific environment are presented. The practices examined affect module size, module strength, data coupling, descendant span, unreferenced variables, and software reuse. Measures characteristic of these practices were extracted from 887 FORTRAN modules developed for five flight dynamics software projects monitored by the Software Engineering Laboratory (SEL). The relationship of these measures to cost and fault rate was analyzed using a contingency table procedure. The results show that some recommended design practices, despite their intuitive appeal, are ineffective in this environment, whereas others are very effective