Scholars in science and technology studies have long been concerned with a variety of issues revolving around technological change, such as explaining the origins of technological innovation and arguing for or against technological determinism. This thesis reviews a number of theoretical models developed by historians, philosophers, sociologists, and other scholars to explain technological change. A case study of technological innovations in industnal forestry and timber harvesting practices provides a basis for a critique of these previously proposed models and for an argument for a new model. This model, an ecological model, suggests homeostatic pressures play a major role in the innovative processes within any technological system. / Master of Science

published_or_final_version / Comparative Literature / Master / Master of Philosophy

The theoretical basis for using electron mirrors as correctors of chromatic aberration is presented and an experimental verification of correction of chromatic aberration is demonstrated. A hyperbolic electrostatic electron mirror operating in its converging range and at unity magnification was used as a corrector. A novel separating system with deflections taking place at image planes was developed to implement the mirror without impairing the resolution. Correction was demonstrated in an electron optical probe system. The chromatic aberration was measured by means of the shadows cast by a fine mesh placed near the final image. The experimental method and equipment are described. The experiment serves as a verification of the theory as well as a successful test of the method of separating the electron beams traveling to and from the mirror.

Thesis (Ph. D.)--University of Delaware, 2007. / Principal faculty advisor: William Latham, III, Dept. of Economics. Includes bibliographical references.

The meteoric rise and prevalent usage of wireless networking technologies for mobile communication applications have captured the attention of media and imagination of public in the recent decade. One such proliferation is experienced in Wireless Sensor Networks (WSNs), where multimedia enabled elements are fused with integrated sensors to empower tightly coupled interaction with the physical world. As a promising alternative to antiquated wired systems and traditional WSNs in a multitude of novel application scenarios, the newly renovated WSNs have inspired a wide range of research among which investigation on data acquisition techniques is a fundamental one. In this dissertation, we address the problem of data acquisition in next generation WSNs. As wireless sensors are powered with limited energy resources while they are expected to work in an unattended manner for a long duration, energy conservation stands as the primal concern. Also, to enable in-situ sensing in different rate-constrained applications, routing decisions should care about the medium access feasibility of achievable end-to-end data rates. Driven by the fact, we first design cross-layer medium contention aware routing schemes for rate-constrained traffic in single-channel WSNs that maximize network lifetime. Three sufficient conditions on rate feasibility, referred to as rate-based, degree-based, and mixed constraints, are incorporated into the routing formulations to guarantee the practical viability of the routing solutions. Next, with the aim to mitigate interference and hence to enhance network capacity, we extend our work by proposing energy and cross-layer aware routing schemes for multichannel access WSNs that account for radio, MAC contention, and network constraints. In that context, we first derive three new sets of sufficient conditions that ensure feasibility of data rates in multichannel access WSNs. Then, utilizing these sets, we devise three different MAC-aware routing optimization schemes, each aiming to maximize the network lifetime while meeting data rate requirements of end-to-end flows. Finally, we perform extensive simulation studies to evaluate and compare the performance of the proposed routing approaches under various network conditions. So far works are done in milieu of WSNs with both fixed access node and sensor nodes. In the subsequent part of the dissertation, we present the continuation of our work focusing on reliable data acquisition in Mobile WSNs for a promising application namely free-ranging animal tracking/monitoring. To accomplish that goal, we concentrate on providing sufficient conditions on access-point density that limit the likelihood of buffer overflow. We first derive sufficient access-point density conditions that ensure that the data loss rates are statistically guaranteed to remain below a given threshold. Then, we evaluate and validate the derived theoretical results with both synthetic and real-world data. / Graduation date: 2012

Texte remanié de: Ph. D. dissertation--Management learning--University of Lancaster, 2004. / Bibliogr. p. 195-208.

Dissertation--Mannheim--Zemtrum für Europaïsche Wirtschaftsforschung, 2005. / Bibliogr. p. 183-194.

Proefschrift--Delft--Technische universiteit, 1998. / Bibliogr. p. 393-404. Résumé en anglais.

Thèse de doctorat : Sciences de gestion : Paris 12 : 2006. / Titre provenant de l'écran-titre.

Thèse de doctorat : Sciences de gestion : Lyon 2 : 1991. / Titre provenant de l'écran-titre.