Bayesian Structural Equation Models for Cumulative Theory Building in Information Systems

Theories are sets of causal relationships between constructs and their proxy indicator variables. Theories are tested and their numerical parameters are estimated using statistical models of latent and observed variables. A considerable amount of theoretical development in Information Systems occurs by theory extension or adaptation. Moreover, researchers are encouraged to reuse existing measurement instruments when possible. As a consequence, there are many cases when a relationship between two variables (latent and/or observed) is re-estimated in a new study with a new sample or in a new context. To aid in cumulative theory building, a re-estimation of parameters should take into account our prior knowledge about their likely values. In this paper, we show how Bayesian statistical models can provide a statistically sound way of incorporating prior knowledge into parameter estimation, allowing researchers to keep a “running tally” of the best estimates of model parameters

Advanced control schemes for wind power plants and renewable energy-based islanded microgrids

Renewable energy sources are increasingly integrated in power grids, creating significant challenges for control and system operation. Among various renewable energy sources, wind power is one of the dominant forms, mainly generated from large-scale transmission-connected wind power plants (WPPs). The grid-connected WPPs are required to follow grid codes to maintain a predefined power factor range under normal operation and supply required reactive power under faulty conditions. To meet grid code requirements, a WPP control architecture is developed in this thesis. The control system consists of a central WPP controller and a local wind turbine generator (WTG) controller, both operate in the voltage control mode. Therefore, the controller can respond faster and is robust to communication failures. Under normal operating conditions, the proposed controller regulates the WPP’s operation within its steady-state reactive power capability and meets the power factor limits. Under faulty conditions, the controller forces the WPP to its maximum capability to contribute more reactive power support to the grid. Two mathematical models representing the steady-state and maximum reactive power capability of the WPP are developed through regression and analytic approaches, respectively. In the second part of the thesis, a model predictive control (MPC)-based distributed generation (DG) controller is proposed to regulate the voltage and frequency at the point of common coupling (PCC) in an islanded microgrid. A data-driven input-output Box-Jenkins polynomial predictive model for DG control is developed using the Gauss-Newton-based nonlinear least square method with the prediction optimization focus. The model inputs are direct- and quadrature-axis components of the control signal, and the model outputs are deviations of the voltage and frequency from their nominal values at the PCC. The proposed MPC controller operates using the PCC data and does not require the microgrid’s central controllers or DG-to-DG communication networks. It can effectively compensate voltage and frequency deviations at the PCC and ensure proportional reactive power sharing among DGs without a secondary controller and a virtual impedance loop. The integrated Kalman filter in the MPC structure enables a robust controller design when subjected to impedance variations and measurement noises

Three-dimensional tomographic reconstruction of an exceptionally well preserved ichnological assemblage from the Stainmore Foundation, Carboniferous, UK

This Ph.D. thesis addresses current issues with ichnotaxonomic practice, and characterizes an exceptionally well preserved ichnological assemblage from the Carboniferous Stainmore Formation, Northumberland, United Kingdom. Samples were collected from closely localized float representative of various units throughout the succession, which was deposited in a storm-dominated marine shoreface. Three dominant ichnotaxa were selected for three-dimensional morphological analysis due to their complicated morphology and/or unclear taxonomic status: 1) Dactyloidites jordii isp. nov.; 2) Beaconites capronus, and; 3) Neoeione moniliformis comb. nov. Using serial grinding and photography, these ichnotaxa were ground and modelled in true colour. High-resolution models of three taxa produced in this study are the basis of the first complete three-dimensional consideration of the traces, and forms the basis for refined palaeobiological and ethological analysis of these taxa. Dactyloidites jordii isp. nov. is a stellate to palmate burrow composed of numerous long, narrow rays that exhibit three orders of branching arranged into tiered galleries radiating from a central shaft. It is considered to be the feeding structure produced by a vermiform organism. Beaconites capronus is a winding trace with distinctly chevron-shaped, meniscate backfill demonstrated herein to backfill the vertical shafts associated with its burrows in a comparable fashion to the horizontal portion of the burrow. This lack of a surface connection would result in the trace making organism being exposed to low-oxygen porewater. Coping with this porewater dysoxia could be approached by burrowing organisms in a number of ways: 1) revisiting the sediment-water interface; 2) creating periodic shafts; or 3) employing anaerobic metabolism. Neoeione moniliformis was originally introduced as Eione moniliformis, however, the genus Eione Tate, 1859 is a junior homonym of Eione Rafinesque, 1814. This led to the transfer of Eione moniliformis to Parataenidium. Through careful examination and three-dimensional characterization of topotypes, the transfer to Parataenidium moniliformis is demonstrated herein to be problematic, as Parataenidium refers to primarily horizontal burrows with two distinct layers and Eione moniliformis is composed of one distinct level. As such, the new ichnogenus Neoeione is created to accommodate Neoeione moniliformis

Biosurfactant production and applications in oil contaminate control

Surfactants are a versatile group of chemicals. They are amphiphilic compounds that exert impacts at interfaces among air, water, oil, and solid phases. Currently, the prevalent players in the market are chemically synthesized surfactants, which have concerns of considerable toxicity and low biodegradability. Because they are mainly derived from fossil fuels, they are not sustainable in the long run and the production costs are subjected to the price variance of raw materials. In view of these limitations, biosurfactants have been proposed as promising alternatives. They are surfactant molecules produced by microorganisms during their growth. Biosurfactants exist naturally in the environment and play some roles in the ecosystem even without human interferences. In this dissertation we define this virtue as “environmental friendly”. They are also renewable and non/less toxic. They have also been found with the intriguing advantages such as enormous structural diversity, lower critical micellar concentrations (CMCs), and the feasibility to use renewable and/or waste streams as the source of production. Biosurfactants are considered as multifunctional biomolecules of the 21st century with a thriving global market share. Their applications in environmental and oil industries are among the top market sectors thanks to their environmental friendly nature. In order to harness the power of biosurfactants, the economic effectiveness of production of these molecules needs improvements. The inocula/microorganisms are the engine of a production process, which determine the maximum yield potential and the functionality of biosurfactants, yet limited inocula have been reported. The functional diversity of biosurfactants includes emulsification, dissolution, dispersion, emulsion breaking, reduction in viscosity, and surface activity, which result in a broad spectrum of potential applications in oil contaminate control including soil washing, enhanced bioremediation, oily wastewater treatment, and spilled oil dispersion. However, limited research efforts have been placed into evaluating the application potential of biosurfactants in oil contaminate control. The objectives of this thesis are to 1) identify novel and robust biosurfactant producing microorganisms and develop hyper-production mutants; 2) examine the functionality of the produced biosurfactants; and 3) investigate the potential of using these produced biosurfactants in diverse applications of oil contaminate control. The outputs of the thesis include: (1) the successful isolation, identification, characterization and functionality analysis of one-hundred-and-fourteen biosurfactant producing and oil degrading marine bacteria; (2) the discovery of a novel bacterial species, Alcanivorax atlaticus for the first time and its proposed type strain with comprehensive genotype and phenotype characterizations; (3) an in-depth characterization, functionality analysis and application demonstration of a novel bioemulsifier (exmulsins) and its bacterium (Exiguobacterium sp. N4-1P); (4) reporting of thirty-seven novel oil-in-water emulsion breaking marine bacteria for oily wastewater treatment, and a recommended screening strategy for their identification; (5) the first attempt to genetically modify Rhodococcus strains for hyper production of biosurfactant and to investigate the dispersing abilities of the the produced biosurfactants; and (6) a comprehensive investigation of 4 types of biosurfactants produced from selected isolates and mutants as marine oil spill dispersants

Design and analysis of a community size solar powered reverse osmosis desalination water system for Pakistan

Water crisis and global warming are two of the biggest challenge of the world. Around 1.1 billion people in the world do not have access to clean water whereas producing water by different purification methods required extensive amount of energy which is generated by burning fossil fuels impacting the environment. This thesis proposes a design of a solar powered reverse osmosis desalination system for a community in Pakistan, which would address the water issue problem for a community in Karachi Pakistan. The design and system sizing of the solar powered reverse osmosis system was done in HOMER Pro followed by techno-economic feasibility analysis of the complete system. The comprehensive dynamic modelling of the system was carried out using the bond graph modelling approach where multidisciplinary systems are modelled using a common bond graph language. 20sim simulation software was used for dynamic analysis of the system. Moreover, a detailed instrumentation system design and control system design was made. After finalization of instrumentation and control design a low-cost, open-source, internet-of-things (IOT) based SCADA system as design was made using field instrument devices and Node-Red. A comprehensive alert system was further integrated with the SCADA design to provide status and updates to the community. Local database was also generated and data was imported by Grafana data analytics tool for making data-driven decisions. A complete laboratory experimental setup was made to verify the SCADA based alert system. Lastly, conclusions are provided based on the research conducted in each section of this thesis, and areas for future research have been identified. This work will provide solution for clean drinking water for a community in Pakistan with robust supervisory control and data acquisition system

A dynamic pressure distribution model for ice pressure load patches used in numerical simulations

The work presents a model for ice load pressure patch representation in numerical structural simulation that captures the non-uniform pressure distribution as a function of the ice-structure interface shape. For this purpose, the first step of the work was the analysis of pressure data from ice impact experiments. This work presents the ice pressure distribution recorded and analysed in high temporal- and spatial-resolutions. The results show regions of high- and low-pressure zones (i.e., HPZ and LPZ) at the ice-indenter interface, which agree with previous works. Furthermore, based on the visual analysis of the pressure maps and ice specimen test faces, it was possible to hypothesise that the pattern assumed by the HPZ could be explained by the shape of the contact area. Based on this observation a geometric model for HPZ and LPZ representation over any contact area was developed and it is presented in this work for the first time. The methodology uses the topological skeleton and distance field information of the ice contact area’s shape to define the HPZ and LPZ associated to a contact area from the high-strain-rate interaction between an ice feature and a flat structure. The results from this methodology compare favourably with experimental observations of the HPZ distribution patterns. Finally, this led to the development of a new energy-coupled ice load model called NILAS (Non-uniform Ice Load Application System). The NILAS is capable of accounting for structural deformation energy during the simulation, while also generating non-uniform ice load pressure patches. The NILAS is designed for use in numerical structural simulations for the assessment of damage to non-polar class structures and overloaded polar class structures. While simpler methods that use uniform pressure patches with correction factors (e.g., IACS UR I) can approximate the effects of load concentration caused by HPZ, the NILAS model can directly include these regions of pressure concentration into the load patch. Therefore, the new model can account for the path-dependent plasticity associated with localized deformation response to the HPZ, which is of particular importance for non-ice class ships and overloaded ice-class ships

Proposition de nouvelles fonctionnalités WikiSIG pour supporter le travail collaboratif en Geodesign

L’émergence du Web 2.0 se matérialise par de nouvelles technologies (API, Ajax…), de nouvelles pratiques (mashup, geotagging…) et de nouveaux outils (wiki, blog…). Il repose principalement sur le principe de participation et de collaboration. Dans cette dynamique, le Web à caractère spatial et cartographique c’est-à-dire, le Web géospatial (ou GéoWeb) connait lui aussi de fortes transformations technologiques et sociales. Le GéoWeb 2.0 participatif se matérialise en particulier par des mashups entre wikis et géobrowsers (ArgooMap, Geowiki, WikiMapia, etc.). Les nouvelles applications nées de ces mashups évoluent vers des formes plus interactives d’intelligence collective. Mais ces applications ne prennent pas en compte les spécificités du travail collaboratif, en particulier la gestion de traçabilité ou l’accès dynamique à l’historique des contributions. Le Geodesign est un nouveau domaine fruit de l’association des SIG et du design, permettant à une équipe multidisciplinaire de travailler ensemble. Compte tenu de son caractère émergent, le Geodesign n’est pas assez défini et il requiert une base théorique innovante, de nouveaux outils, supports, technologies et pratiques afin de s'adapter à ses exigences complexes. Nous proposons dans cette thèse de nouvelles fonctionnalités de type WikiSIG, bâties sur les principes et technologies du GéoWeb 2.0 et visant en particulier à supporter la dimension collaborative du processus de Geodesign. Le WikiSIG est doté de fonctionnalités wiki dédiées à la donnée géospatiale (y compris dans sa composante géométrique : forme et localisation) permettant d’assurer, de manière dynamique, la gestion documentée des versions des objets et l’accès à ces versions (et de leurs métadonnées), facilitant ainsi le travail collaboratif en Geodesign. Nous proposons également la deltification qui consiste en la capacité de comparer et d’afficher les différences entre deux versions de projets. Finalement la pertinence de quelques outils du géotraitement et « sketching » est évoquée. Les principales contributions de cette thèse sont d’une part d’identifier les besoins, les exigences et les contraintes du processus de Geodesign collaboratif, et d’autre part de proposer des nouvelles fonctionnalités WikiSIG répondant au mieux à la dimension collaborative du processus. Pour ce faire, un cadre théorique est dressé où nous avons identifié les exigences du travail collaboratif de Geodesign et proposé certaines fonctionnalités WikiSIG innovantes qui sont par la suite formalisés en diagrammes UML. Une maquette informatique est aussi développée de façon à mettre en oeuvre ces fonctionnalités, lesquelles sont illustrées à partir d’un cas d’étude simulé, traité comme preuve du concept. La pertinence de ces fonctionnalités développées proposées est finalement validée par des experts à travers un questionnaire et des entrevues. En résumé, nous montrons dans cette thèse l’importance de la gestion de la traçabilité et comment accéder dynamiquement à l’historique dans un processus de Geodesign. Nous proposons aussi d’autres fonctionnalités comme la deltification, le volet multimédia supportant l’argumentation, les paramètres qualifiant les données produites, et la prise de décision collective par consensus, etc.The emergence of Web 2.0 is materialized by new technologies (APIs, Ajax ...), by new practices (mashup, geotagging ...) and by new tools (wiki, blog ...). It is primarily based on the principle of participation and collaboration. In this dynamic, the web mapping with spatial character or simply called Geospatial Web (or Geoweb) evolves by strong technological and social changes. Participatory GeoWeb 2.0 is materialized in particular by mashups among wikis and géobrowsers (ArgooMap, Geowiki, WikiMapia, etc.). The new applications resulting from these mashups are moving towards more interactive forms of collective intelligence. However, these applications do not take into account the collaborative work or the traceability management or the dynamic access to the history of contributions. The Geodesign is a new area, which is the coupling between GIS and design, allowing a multidisciplinary team to work together. As it is an emergent term, the Geodesign has not be well defined and it requires innovative theoretical basis, new tools, media, technologies and practices to fit its complex requirements. We propose precisely in this thesis new features of WikiGIS, which is built on Web 2.0 technologies, and GeoWeb 2.0 aiming in particular to support the collaborative dimension of Geodesign process. The WikiGIS consists of wiki features for the geospatial data (including its geometric component: shape and location) to ensure, dynamically, the documented release management objects and access to these versions (and metadata), facilitating collaborative work on Geodesign. It aims to produce geographic information, while ensuring the quality and credibility of data created. We propose the “deltification” as one of the innovative features of WikiGIS, it is the ability to compare and display the differences between two versions of a project. Finally, the relevance of some geoprocessing and "sketching" tools is mentioned. The main contributions of the present thesis are firstly identifying the needs, requirements and constraints of collaborative Geodesign process, and secondly to offer new features of WikiSIG best meeting to the collaborative dimension of this process. For this, a theoretical framework is drawn up which we identified the requirements of the collaborative Geodesign process and we proposed some innovative features that are subsequently formalized by UML. A user mock-up is developed in order to show the WikiGIS features, which are illustrated on a simulated case study, treated as proof of concept. Finally, these concepts are ultimately validated by experts through a questionnaire and interviews. Briefly, we have amply demonstrated in this thesis the importance of traceability management and how to dynamically access in the historic of Geodesign process and we have proposed other features like deltification, multi-media component that supports the arguments, parameters describing the data produced, decision making by consensus, etc

Breakthroughs and emerging insights from ongoing design science projects: Research-in-progress papers and poster presentations from the 11th international conference on design science research in information systems and technology (DESRIST) 2016. St. John, Newfoundland, Canada, May 23-25

This volume contains selected research-in-progress papers and poster presentations from DESRIST 2016 - the 11th International Conference on Design Science Research in Information Systems and Technology held during 24-25 May 2016 at St. John's, Newfoundland, Canada. DESRIST provides a platform for researchers and practitioners to present and discuss Design Science research. The 11th DESRIST built on the foundation of ten prior highly successful international conferences held in Claremont, Pasadena, Atlanta, Philadelphia, St. Gallen, Milwaukee, Las Vegas, Helsinki, Miami, and Dublin. This year's conference places a special emphasis on using Design Science to engage with the growing challenges that face society, including (but not limited to) demands on health care systems, climate change, and security. With these challenges in mind, individuals from academia and industry came together to discuss important ongoing work and to share emerging knowledge and ideas. Design Science projects often involve multiple sub-problems, meaning there may be a delay before the final set of findings can be laid out. Hence, this volume "Breakthroughs and Observations from Ongoing Design Science Projects" presents preliminary findings from studies that are still underway. Completed research from DESRIST 2016 is presented in a separate volume entitled "Tackling Society's Grand Challenges with Design Science", which is published by Springer International Publishing, Switzerland. The final set of accepted papers in this volume reflects those presented at DESRIST 2016, including 11 research-in-progress papers and 4 abstracts for poster presentations. Each research-in-progress paper and each poster abstract was reviewed by a minimum of two referees. We would like to thank the authors who submitted their research-in-progress papers and poster presentations to DESRIST 2016, the referees who took the time to construct detailed and constructive reviews, and the Program Committee who made the event possible. Furthermore we thank the sponsoring organisations, in particular Maynooth University, Claremont Graduate University, and Memorial University of Newfoundland, for their financial support. We believe the research described in this volume addresses some of the most topical and interesting design challenges facing the field of information systems. We hope that readers find the insights provided by authors as valuable and thought-provoking as we have, and that the discussion of such early findings can help to maximise their impact

Sedimentology and palaeontology of the Withycombe Farm Borehole, Oxfordshire, England

The pre-trilobitic lower Cambrian of the Withycombe Formation is a 194 m thick siliciclastic succession dominated by interbedded offshore red to purple and green pyritic mudstone with minor sandstone. The mudstone contains a hyolith-dominated small shelly fauna including: orthothecid hyoliths, hyolithid hyoliths, the rostroconch Watsonella crosbyi, early brachiopods, the foraminiferan Platysolenites antiquissimus, the coiled gastropod-like Aldanella attleborensis, halkieriids, gastropods and a low diversity ichnofauna including evidence of predation by a vagile infaunal predator. The assemblage contains a number of important index fossils (Watsonella, Platysolenites, Aldanella and the trace fossil Teichichnus) that enable correlation of strata around the base of Cambrian Stage 2 from Avalonia to Baltica, as well as the assessment of the stratigraphy within the context of the lower Cambrian stratigraphic standards of southeastern Newfoundland. The pyritized nature of the assemblage has enabled the study of some of the biota using micro-CT, augmented with petrographic studies, revealing pyritized microbial filaments of probable giant sulfur bacteria. We aim to produce the first complete description of the core and the abundant small pyritized fossils preserved in it, and develop a taphonomic model for the pyritization of the “small” shelly fossils