Dissertations / Theses: 'Structured Environments'

1

Friedlander, Ronn S. (Ronn Samuel). "Bacterial adhesion in structured environments." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95862.

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Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Biofilms-surface-bound communities of microbes-are a major medical concern, as they can be sources of infection that are difficult to eradicate. Their formation starts with the attachment of bacteria to available surfaces-often implantable biomaterials. The development of materials that prevent bacterial adhesion is therefore of paramount importance, and it requires a thorough understanding of the materials and bacterial surface properties that enable adhesive interactions. We herein design model surfaces and examine the interplay between micro-scale geometry, surface energy and bacterial surface properties with respect to adhesion, with the ultimate goal of understanding bacterial adhesion in structured environments, and establishing principles for design of novel surfaces that effectively repel bacteria. We first study adhesion of Escherichia coli to engineered surfaces possessing superficially unfavorable geometries. We show that cells can overcome geometric constraints with the aid of flagella, which are able to reach between narrow crevices, thus improving adhesion and expanding the range of surfaces to which cells can adhere. We examine binding of purified flagella to abiotic surfaces by means of quartz crystal microbalance (QCM) and show that flagella bind preferentially to hydrophobic surfaces, yet they do not appreciably bind to hydrophilic surfaces. Using mutant strains, we investigate the role of flagella in surface attachment of live cells and demonstrate that flagellated cells adhere best to hydrophobic substrates; however flagella may impede cell adhesion to hydrophilic surfaces. To further explore hydrophilic, structured environments with physiological relevance, we examine mucin-a natural hydrogel that typically harbors microbes in animals, while protecting the host. We purify mucins and use them in their native, three-dimensional configuration to probe bacterial swimming behavior and surface attachment in their presence. We demonstrate that mucins maintain-and possibly enhance-swimming ability for E. coli and Pseudomonas aeruginosa, and show that they greatly reduce adhesion to underlying substrates. Finally, we build on our established design principles and construct anti-adhesive surfaces by combining hydrophilic chemistries with topographic features smaller than cellular dimensions. This work suggests a path toward anti-adhesive materials that may be optimized for mechanical robustness, longevity and specific environments of application.
by Ronn S. Friedlander.
Ph. D.

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2

Almajano, Pablo. "Assisted Hybrid Structured 3D Virtual Environments." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285805.

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The blending of digital technologies, such as artificial intelligence, interactive systems, 3D interfaces and the Internet is enabling new services for users. In particular, Hybrid Structured 3D Virtual Environments (VE) provide users with a collaborative space not only for entertainment and socialization but also for developing “serious” applications such as e-learning, e-government and e-commerce. This thesis focuses on Hybrid Structured 3D VE, which are persistent multiuser systems where participants (both human users and software agents) develop “serious” activities. In these systems the 3D interface graphically represents the system and facilitates human participation, and an Organisation Centred Multi-Agent System (OCMAS) structures participants’ interactions. To do so, the OCMAS specifies the roles that participants can enact, the activities where complex tasks can be accomplished, and communication protocols that enable the prosecution of such tasks. Nevertheless, participating in these systems is not a straight-forward process. Specifically, when the system speci.cation is complex, participants have to perform intricate reasoning processes to understand their applicable regulations at current system state; and they do not have access to information about what happened before they entered the system, neither can further process this information. Moreover, software agents speak a computer-based language, which is usually hard to use by human users. Then, as human users interact with staff agents (software agents devoted to support the system activities) to complete tasks, human-agent interaction style becomes a key issue. In order to overcome these limitations, this work proposes Assisted Hybrid Structured 3D Virtual Environments, where both human users and software agents participation in the system is improved by both assistance and humanagent interaction mechanisms. The system is formalised as a two layered infrastructure. The Organisational Layer structures the interactions of participants, and the Assistance Layer is populated by a set of Personal Assistants in charge of providing with a set of Assistance services to a system participant. There are four types of Assistance services: i) an Information service that processes data about the organisation specification, the participant current state, and the organisational historical execution states; ii) a Justi.cation service that can be triggered once a participant tries to execute a non-valid or prohibited action; iii) an Estimation service that processes whether an action can be performed at current state prior to its execution or not and, if it is actually the case, then it also provides the next system state; and iv) an Advice service, which provides participants with a sequence of actions (i.e. plans) to achieve their goals. Moreover, this work implements and evaluates v-mWater, a virtual market based on trading water, modelled as an Assisted Hybrid Structured 3D Virtual Environment. The usability evaluation results of v-mWater show that it is perceived as a useful and powerful application that could facilitate everyday tasks in the future. Users like its learnability, its immersiveness, and how scenario settings facilitate task accomplishment. In general, users completed the proposed task well and they were able to go to the right destination in the scenario. After doing the test, users improved their opinion about 3D virtual environments. In addition, the overall opinion of the human-agent interaction was positive. Nevertheless, those users less familiar with new technologies experimented problems when using a command-based system to interact with staff agents. To support assistance services in the system, this work designs and evaluates an Assistance Architecture where the Information service is implemented for software agents; and the Justi.cation, Estimation and the planning Advice service for human users. Nonetheless, these four services could be offered interchangeably for both humans and software agents, since they all simplify the reasoning process as well as the cognitive load required to participate in these complex structured systems. Speci.cally, the Information service has been extended to help sellers to set the price in their transactions. The tests performed compare the values that different agent satisfaction parameters and system goals take when agents request for different information services, using as a base-line a con.guration without enabling assistance services. The experiments show that system performance and agent satisfaction (and thus, the quality of assistance service) increase with the addition of the information service. Furthermore, individual agents following alternative strategies can request di.erent information as a useful decision support tool. The planning Advice service is the most sophisticated one and makes use of the rest of services to provide a plan that has into account other participants actions and, executed at current system state, will lead to the user’s goal. It is implemented as an extension of A*, namely Plan-eA. Evaluation results indicate that assistance impacts positively in usability measures of efficiency, efficacy and satisfaction. Related to human-agent interaction, this work integrates a new conversational mechanism within VIXEE, an execution infrastructure for Hybrid Structured 3D Virtual Environments. This new mechanism includes a task-oriented conversational system, which allows staff agents to dialogue with human users using natural language conversations. To do so, this work proposes an extension of the well-known AIML language, namely Task-Oriented AIML, for dealing with task-oriented conversations, which are based on activities’ specification and current system state. Test results give good usability measures of efficiency, efficacy and user satisfaction for the conversational approach.

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Igarashi, Ayumi. "Fairness and stability in structured environments." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:739e1784-f88b-4285-93d4-02d019e0a684.

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In many social and economic situations, networks are the primary vehicle for strategic interactions among multiple players. On the one hand, networks connect individuals and represent how they interact with each other. On the other hand, networks describe relations between objects that are of interest to multiple decision-makers. The aims of the thesis are two-fold: first, to describe how the underlying network structures affect the existence of desirable outcomes of strategic interactions; and second, to discuss computational issues that arise when considering problems with connectivity constraints imposed by a network. In particular, we will consider two settings in which networks play a critical role: coalition formation and fair division restricted by networks. Specifically, we will study a model in which the space of feasible outcomes is restricted to the connected subgraphs of an underlying network. In essence, we show that acyclicity of a network is a necessary and sufficient condition for desirable outcomes to exist and to be efficiently computable.

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4

Rosenquist, Calle, and Andreas Evesson. "Visual Servoing In Semi-Structured Outdoor Environments." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-653.

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The field of autonomous vehicle navigation and localization is a highly active research

topic. The aim of this thesis is to evaluate the feasibility to use outdoor visual navigation in a semi-structured environment. The goal is to develop a visual navigation system for an autonomous golf ball collection vehicle operating on driving ranges.

The image feature extractors SIFT and PCA-SIFT was evaluated on an image database

consisting of images acquired from 19 outdoor locations over a period of several weeks to

allow different environmental conditions. The results from these tests show that SIFT-type

feature extractors are able to find and match image features with high accuracy. The results also show that this can be improved further by a combination of a lower nearest neighbour threshold and an outlier rejection method to allow more matches and a higher ratio of correct matches. Outliers were found and rejected by fitting the data to a homography model with the RANSAC robust estimator algorithm.

A simulator was developed to evaluate the suggested system with respect to pixel noise from illumination changes, weather and feature position accuracy as well as the distance to features, path shapes and the visual servoing target image (milestone) interval. The system was evaluated on a total of 3 paths, 40 test combinations and 137km driven. The results show that with the relatively simple visual servoing navigation system it is possible to use mono-vision as a sole sensor and navigate semi-structured outdoor environments such as driving ranges.

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5

Snell, Eric Jeffrey. "Pest management program for structured urban environments." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-05022009-040516/.

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6

D'Cruz, Mirabelle. "Structured evaluation of training in virtual environments." Thesis, University of Nottingham, 1999. http://eprints.nottingham.ac.uk/11109/.

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Virtual Environments (VEs) created through Virtual Reality (VR) technologies have been suggested as potentially beneficial for a number of applications. However a review of VEs and VR has highlighted the main barriers to implementation as: current technological limitations; usability issues with various systems; a lack of real applications; and therefore little proven value of use. These barriers suggest that industry would benefit from some structured guidance for developing effective VEs. To examine this ‘training’ was chosen to be explored, as it has been suggested as a potential early use of VEs and is of importance to many sectors. A review of existing case studies on VE training applications (VETs) examined type of training applications and VR systems being considered; state of development of these applications and results of any evaluation studies. In light of these case studies, it was possible to focus this work on the structured evaluation of training psycho-motor skills using VEs created by desktop VR. In order to perform structured evaluation, existing theories of training and evaluation were also reviewed. Using these theories, a framework for developing VETs was suggested. Applying this framework, two VETs were proposed, specified, developed and evaluated. Conclusions of this work highlighted the many areas in the development process of an effective VET that still need addressing. In particular, in the proposal stage, it is necessary to provide some guidance on the appropriateness of VET for particular tasks. In the specification and building stages, standard formats and techniques are required in order to guide the VE developer(s) in producing an effective VET. Finally in the evaluation stage, there are still tools required that highlight the benefits of VET and many more evaluation studies needed to contribute information back to the development process. Therefore VEs are still in their early stages and this work unifies existing work in the area specifically on training and highlights the gaps that need to be addressed before widespread implementation.

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7

Harati, Ahad. "Simultaneous localization and mapping for structured indoor environments /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17938.

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8

Liu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231945394343-32656.

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The properties of a Rydberg atom immersed in an ultracold environment were investigated. Two scenarios were considered, one of which involves the neighbouring ground-state atoms arranged in a spatially structured configuration, while the other involves them distributed randomly in space. To calculate the influence of the multiple ground-state atoms on the Rydberg atom, Fermi-pseudopotential was used, which simplified greatly the numerical effort. In many cases, the few-body interaction can be written down analytically which reveals the symmetry properties of the system. In the structured case, we report the first prediction of the formation of ``Rydberg Borromean trimers''. The few-body interactions and the dynamics of the linear A-B-A trimer, where A is the ground-state atom and B is the Rydberg atom, were investigated in the framework of normal mode analysis. This exotic ultralong-range triatomic bound state exists despite that the Rydberg-ground-state interaction is repulsive. Their lifetimes were estimated using both quantum scattering calculations and semi-classical approximations which are found to be typically sub-microseconds. In the disordered case, the Rydberg-excitation spectra of a frozen-gas were simulated, where the nuclear degrees of freedom can be ignored. The systematic change of the spectral shape with respect to the density of the gas and the excitation of the Rydberg atom were found and studied. Some parts of the spectral shape can be described by simple scaling laws with exponents given by the basic properties of the atomic species such as the polarizability and the zero-energy electron-atom scattering length.

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9

Saretto, Cesare John. "Mediating User Interaction In Narrative-Structured Virtual Environments." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010803-153815.

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Films and novels effectively convey intriguing stories, powerful emotions, and meaningful messages to their audiences. Telling interactive stories in a virtual environment seems a natural progression of the narrative. Users find virtual environments more engaging when they perceive that they have agency within those environments. The greater the sense of freedom they have over choosing and executing their own actions, the greater their sense of agency will be. However, in order to maintain the coherence of their stories, current attempts at interactive narrative environments often limit a users sense of agency by restricting his ability to affect critical elements of the story. The process of mediation is designed to give users as great a sense of agency in an unfolding narrative as possible while still maintaining the narrative's coherence and goals. This is accomplished by making the system, user, and author collaborators in the production of the storyline. This collaboration takes the form of a mediation system constantly rewriting the narrative within the confines of the author's goals as the user interacts with characters and objects in the virtual environment.

Mediation assumes that an effective narrative storyline can be modeled by a fully ordered series of actions (know as a plan) performed by one or more virtual characters in a virtual environment. A mediation system is composed of three primary components: a speculative planner, a decision cache data structure, and an execution monitor. The speculative planner is constantly analyzing the storyline to determine what actions a user could perform that would prevent the storyline from reaching its end. For each such action it utilizes a narrative planner to determine if the storyline can be rewritten around the action or if the action must be prevented. One way of realistically preventing an action is modeled by failure modes. Failure modes are alternative actions that can be substituted by the system when necessary for user-attempted actions.

The decisions of the speculative planner are stored in the decision cache data structure that is used by the execution monitor. The execution monitor observes users in the virtual environment and the actions they perform. If any user attempts an action in the decision cache, the execution monitor alerts the speculative planner and takes preventive action if necessary.

Mediation is a prime candidate for use in narrative environments that require a great deal of user interaction and freedom. Most notable are entertainment and educational systems. More generally, mediation concepts can be applied to many varying collaborative application environments, such as on-screen agents that advise or assist users in the achievement of goals. Mediation frees users from the limitations of a system's author's ability to predict all combinations of actions a user may wish to perform in a virtual environment.

In this work we describe a prototype of the execution monitor component of mediation that has been implemented in Mimesis, a virtual environment architecture designed for interactive narrative [37].

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10

Calandriello, Daniele. "Efficient sequential learning in structured and constrained environments." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10216/document.

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L'avantage principal des méthodes d'apprentissage non-paramétriques réside dans le fait que la nombre de degrés de libertés du modèle appris s'adapte automatiquement au nombre d'échantillons. Ces méthodes sont cependant limitées par le "fléau de la kernelisation": apprendre le modèle requière dans un premier temps de construire une matrice de similitude entre tous les échantillons. La complexité est alors quadratique en temps et espace, ce qui s'avère rapidement trop coûteux pour les jeux de données de grande dimension. Cependant, la dimension "effective" d'un jeu de donnée est bien souvent beaucoup plus petite que le nombre d'échantillons lui-même. Il est alors possible de substituer le jeu de donnée réel par un jeu de données de taille réduite (appelé "dictionnaire") composé exclusivement d'échantillons informatifs. Malheureusement, les méthodes avec garanties théoriques utilisant des dictionnaires comme "Ridge Leverage Score" (RLS) ont aussi une complexité quadratique. Dans cette thèse nous présentons une nouvelle méthode d'échantillonage RLS qui met à jour le dictionnaire séquentiellement en ne comparant chaque nouvel échantillon qu'avec le dictionnaire actuel, et non avec l'ensemble des échantillons passés. Nous montrons que la taille de tous les dictionnaires ainsi construits est de l'ordre de la dimension effective du jeu de données final, garantissant ainsi une complexité en temps et espace à chaque étape indépendante du nombre total d'échantillons. Cette méthode présente l’avantage de pouvoir être parallélisée. Enfin, nous montrons que de nombreux problèmes d'apprentissage non-paramétriques peuvent être résolus de manière approchée grâce à notre méthode
The main advantage of non-parametric models is that the accuracy of the model (degrees of freedom) adapts to the number of samples. The main drawback is the so-called "curse of kernelization": to learn the model we must first compute a similarity matrix among all samples, which requires quadratic space and time and is unfeasible for large datasets. Nonetheless the underlying effective dimension (effective d.o.f.) of the dataset is often much smaller than its size, and we can replace the dataset with a subset (dictionary) of highly informative samples. Unfortunately, fast data-oblivious selection methods (e.g., uniform sampling) almost always discard useful information, while data-adaptive methods that provably construct an accurate dictionary, such as ridge leverage score (RLS) sampling, have a quadratic time/space cost. In this thesis we introduce a new single-pass streaming RLS sampling approach that sequentially construct the dictionary, where each step compares a new sample only with the current intermediate dictionary and not all past samples. We prove that the size of all intermediate dictionaries scales only with the effective dimension of the dataset, and therefore guarantee a per-step time and space complexity independent from the number of samples. This reduces the overall time required to construct provably accurate dictionaries from quadratic to near-linear, or even logarithmic when parallelized. Finally, for many non-parametric learning problems (e.g., K-PCA, graph SSL, online kernel learning) we we show that we can can use the generated dictionaries to compute approximate solutions in near-linear that are both provably accurate and empirically competitive

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11

Liu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23624.

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The properties of a Rydberg atom immersed in an ultracold environment were investigated. Two scenarios were considered, one of which involves the neighbouring ground-state atoms arranged in a spatially structured configuration, while the other involves them distributed randomly in space. To calculate the influence of the multiple ground-state atoms on the Rydberg atom, Fermi-pseudopotential was used, which simplified greatly the numerical effort. In many cases, the few-body interaction can be written down analytically which reveals the symmetry properties of the system. In the structured case, we report the first prediction of the formation of ``Rydberg Borromean trimers''. The few-body interactions and the dynamics of the linear A-B-A trimer, where A is the ground-state atom and B is the Rydberg atom, were investigated in the framework of normal mode analysis. This exotic ultralong-range triatomic bound state exists despite that the Rydberg-ground-state interaction is repulsive. Their lifetimes were estimated using both quantum scattering calculations and semi-classical approximations which are found to be typically sub-microseconds. In the disordered case, the Rydberg-excitation spectra of a frozen-gas were simulated, where the nuclear degrees of freedom can be ignored. The systematic change of the spectral shape with respect to the density of the gas and the excitation of the Rydberg atom were found and studied. Some parts of the spectral shape can be described by simple scaling laws with exponents given by the basic properties of the atomic species such as the polarizability and the zero-energy electron-atom scattering length.

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12

Stephenson, Peter Reynolds. "Structured investigation of digital incidents in complex computing environments." Thesis, Oxford Brookes University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405872.

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13

VanMiddlesworth, Mark (Mark Allen). "Toward autonomous underwater mapping in partially structured 3D environments." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87791.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 93-100).
Motivated by inspection of complex underwater environments, we have developed a system for multi-sensor SLAM utilizing both structured and unstructured environmental features. We present a system for deriving planar constraints from sonar data, and jointly optimizing the vehicle and plane positions as nodes in a factor graph. We also present a system for outlier rejection and smoothing of 3D sonar data, and for generating loop closure constraints based on the alignment of smoothed submaps. Our factor graph SLAM backend combines loop closure constraints from sonar data with detections of visual ducial markers from camera imagery, and produces an online estimate of the full vehicle trajectory and landmark positions. We evaluate our technique on an inspection of a decomissioned aircraft carrier, as well as synthetic data and controlled indoor experiments, demonstrating improved trajectory estimates and reduced reprojection error in the final 3D map.
by Mark VanMiddlesworth.
S.M.

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14

Greenall, John Patrick. "High-level activity learning and recognition in structured environments." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/3231/.

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Automatic recognition of events in video is an immensly challenging problem. If solved, the number of potential domains in which such a system could be deployed is vast and growing; including traffic monitoring, surveillance, security, elderly care and semantic video search to name but a few. Much prior research in the area has focused on producing a solution that is tailored towards one of these applications, applying methods which are most appropriate given the constraints of the target domain. For the moment, this remains to some extent the only practical way to approach the problem. The aim in this thesis is to build a high-level framework for event recognition which is in the main generic and widely transferrable, yet allows domain-appropriate elements to be incorporated. A detector is constructed for low-level events which is based on dense extraction of Histograms of Optical Flow. This descriptor has only recently been adopted by the event detection community, and as such there are aspects of the features which have not been optimized. This thesis performs extensive experimentation on normalization scheme and finds that the strategy most widely in use is suboptimal compared to one of the alternatives proposed. The detector is then trained on a challenging real world domain to run in a sliding window fashion on continuous video input. A high level model which exploits temporal relations between different event types is constructed. The model is designed with transferrability and computational tractability in mind. Several methods are benchmarked for learning the distributions over time differences between pairs of events. Three different connection strategies are proposed and evaluated for creating a tree structured prior that permits fast, exact inference. An efficient iterative optimization scheme is presented for handling scenarios which contain unknown numbers of event instances. Finally, the model is extended in a Conditional Random Field framework that allows weights to be learned to balance the response from independent detectors with the pairwise temporal relationships.

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Repo, T. (Tapio). "Modeling of structured 3-D environments from monocular image sequences." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514268571.

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Abstract The purpose of this research has been to show with applications that polyhedral scenes can be modeled in real time with a single video camera. Sometimes this can be done very efficiently without any special image processing hardware. The developed vision sensor estimates its three-dimensional position with respect to the environment and models it simultaneously. Estimates become recursively more accurate when objects are approached and observed from different viewpoints. The modeling process starts by extracting interesting tokens, like lines and corners, from the first image. Those features are then tracked in subsequent image frames. Also some previously taught patterns can be used in tracking. A few features in the same image are extracted. By this way the processing can be done at a video frame rate. New features appearing can also be added to the environment structure. Kalman filtering is used in estimation. The parameters in motion estimation are location and orientation and their first derivates. The environment is considered a rigid object in respect to the camera. The environment structure consists of 3-D coordinates of the tracked features. The initial model lacks depth information. The relational depth is obtained by utilizing facts such as closer points move faster on the image plane than more distant ones during translational motion. Additional information is needed to obtain absolute coordinates. Special attention has been paid to modeling uncertainties. Measurements with high uncertainty get less weight when updating the motion and environment model. The rigidity assumption is utilized by using shapes of a thin pencil for initial model structure uncertainties. By observing continuously motion uncertainties, the performance of the modeler can be monitored. In contrast to the usual solution, the estimations are done in separate state vectors, which allows motion and 3-D structure to be estimated asynchronously. In addition to having a more distributed solution, this technique provides an efficient failure detection mechanism. Several trackers can estimate motion simultaneously, and only those with the most confident estimates are allowed to update the common environment model. Tests showed that motion with six degrees of freedom can be estimated in an unknown environment. The 3-D structure of the environment is estimated simultaneously. The achieved accuracies were millimeters at a distance of 1-2 meters, when simple toy-scenes and more demanding industrial pallet scenes were used in tests. This is enough to manipulate objects when the modeler is used to offer visual feedback.

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Eastgate, Richard Mark. "The structured development of virtual environments : enhancing functionality and interactivity." Thesis, University of Nottingham, 2001. http://eprints.nottingham.ac.uk/10954/.

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Desktop Virtual Reality (VR) is an easy and affordable way to implement VR technology within an organisation. It provides an experience that can be shared by many people, and its 3D, interactive capability facilitates the communication of ideas not possible using other media formats. There are a number of software toolkits available for the building and programming of Virtual Environments (VEs), but very few resources that can help developers acquire the skills and techniques required to give their VEs utility and usability. This thesis reviews existing research into VE design with an emphasis on interactivity and usability, and then uses a case study based approach to conceptualise the VE development process and develop exemplar guidance tools. The first group of case studies date from the early 1990s, with an emphasis on finding ways to build VEs incorporating functionality. The experience gained through these case studies was used to discover the issues most relevant to the VE developer and report on the techniques used to resolve them. Several models are then presented to explain these techniques and relate them to the VE development context. For the second set of case studies the emphasis moves to finding ways of making VEs more usable. Several approaches are presented and further conceptualisation results in a decision table based guidance tool. The third set of case studies was carried out within the framework provided by the Virtual Environment Development Structure (VEDS), developed jointly by the author and other members of the Virtual Reality Applications Research Team (VIRART) at the University of Nottingham. In the light of this practical application of the framework and the experience gained throughout the case studies, changes are made to the structure to make it more accurately represent the actual process employed by VE developers. This version of VEDS is then used to more effectively define the areas where VE development guidance tools are needed. Using this information, and based on the experience acquired and the techniques developed throughout this research, three exemplar tools are presented.

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Proenca, Pedro F. "Robust RGB-D odometry under depth uncertainty for structured environments." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/849961/.

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Visual odometry, the process of tracking the trajectory of a moving camera based on its captured video is a fundamental problem behind autonomous mobile robotics and augmented reality applications. Yet, despite almost 40 years of extensive research on the problem, state-of-the-art systems are still vulnerable to several pitfalls that arise in challenging environments due to specific sensor limitations and restrictive assumptions. This thesis, in particular, investigates the use of RGB-D cameras for robust visual odometry in man-made environments, such as industrial plants. These spaces, contrary to natural environments, follow mainly a rectilinear structure made of simple geometric entities. Thus, this work exploits this structure by taking a feature-based approach, where lines, planes and cylinder segments are explicitly extracted as visual cues for egomotion estimation. While the depth captured by RGB-D cameras helps to resolve the ambiguity inherent of passive cameras especially on uniform and low textured surfaces, these active cameras suffer from several limitations, which may deteriorate the performance of RGB-D Odometry, such as, limited operating range, near-infrared light interference and systematic errors, leading to incomplete and noisy depth maps. To address these issues, we have first developed a visual odometry framework that leverages both depth measurements from active sensing and depth estimates from temporal stereo obtained via probabilistic filtering. Our experiments demonstrate that this framework is able to operate on large indoor and outdoor spaces, where the absence and inaccuracy of depth measurements is too high to rely just on RGB-D Odometry. Secondly, this thesis considers the depth sensor error by proposing a depth fusion framework based on Mixture of Gaussians to denoise the depth measurements and model their uncertainties through spatio-temporal observations. Extensive results on RGB-D sequences show that applying this depth model to RGB-D odometry improves significantly its performance and supports our hypothesis that the uncertainty of fused depth needs to be exposed. To fully exploit this probabilistic depth model, the depth uncertainty needs to be propagated throughout the visual odometry pipeline. Therefore, we reformulated the visual odometry system as a probabilistic process by (i) deriving plane and 3D line fitting solutions that model the uncertainties of the feature parameters and (ii) estimating the camera pose by combining different feature-type matches weighted by their respective uncertainties. Lastly, this thesis addresses man-made environments made also of smooth curved surfaces by proposing a curve-aware plane and cylinder extraction algorithm which is shown empirically to be more efficient and accurate than an alternative state-of-the-art plane extraction approach, leading ultimately to better visual odometry performance in scenes made of cylindrical surfaces. To incorporate this feature extractor in visual odometry, the system described above is extended to handle cylinder primitives.

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Brändström, Samuel. "Invasion-analysis of stage-structured populations in temporally-varying environments." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149324.

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Climate change may cause epidemic threats as species spreading human diseases invades previously unpopulated areas. A species can establish in new areas if they fulfills an invasion criterion. Two common invasion criteria are the long-term exponential growth-rate, r, and the basic reproduction number, R0, that measures the population's exponential growth in time and growth between generations respectively. Previous work have determined the long-term exponential growth-rate of the mosquito Aedes aegypti, a vector spreading dengue, zika and yellow fever, in Europe. However, in epidemiology r is rarely used as invasion criterion, which makes their results difficult to communicate and interpret. A more commonly used invasion criterion is the basic reproduction number R0. From this number, public health receives information about high-risk areas where they can vaccinate the population and prevent the mosquitoes from establishing by reducing breeding habitats. Here we extend the previous work by developing a method to calculate R0 for Aedes aegypti and verify it by the results from previous studies. Using R0 as invasion criterion we then predict the global distribution of Aedes aegypti during different climate change scenarios in the 21st century. One related to high emissions of greenhouse gases, RCP8.5, and one to low emissions, RCP2.6. We predict that the distribution of Aedes aegypti will expand towards higher latitudes at great speed during the 21st century assuming the high emission scenario RCP8.5. Assuming the low emission scenario RCP2.6, the distribution will not reach higher latitudes at the end of the 21st century. In Europe, the distribution covered 1.8 % in the beginning of the 20th century and at the end of the 21st century the distribution will cover 10 % assuming RCP8.5 and 2.0 % assuming RCP2.6. This work underscores the importance of reducing global warming and to take other preventive actions to avoid major epidemic outbreaks. Since we also provide instructions and software to calculate both r and R0 for stage-structured models in periodic environments, we anticipate that this work will support more studies of this kind to better understand the epidemic threats from climate change.

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Bharadwaj, Akshay S. "A Perception Payload for Small-UAS Navigation in Structured Environments." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1533649419108963.

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Narayana, Keerthi. "Solutions for the localization of mobile mapping systems in structured environments." Paris, ENMP, 2011. http://pastel.archives-ouvertes.fr/docs/00/61/79/85/PDF/Solutions_de_localisation_des_SystA_mes_Mobiles_de_Cartographie_en_environnements_structurA_s.pdf.

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La localisation automatique est une fonctionnalité importante des systèmes de cartographie mobiles (Mobile Mapping Systems, MMS). La présente thèse présente des solutions complémentaires aux méthodes de localisation utilisées actuellement dans un système MMS terrestre, qui utilise des récepteurs GPS et des centrales à inertie (Inertial Measurement Units, IMU). Un post-traitement, par lissage des données, permet d'améliorer les cartes 3D générées par un MMS. Cette approche est cependant insuffisante pour corriger les erreurs à variations lentes des capteurs. La présente thèse propose une technique de localisation alternative, fondée sur des scanners 2D à lasers. La méthode présentée ici, d'odométrie par laser, utilise des repères plans, qui sont fréquents dans les environnements créés par l'Homme : ces repères fixes permettent de déterminer le déplacement opéré par la plateforme mobile. Contrairement à la technique du SLAM (Simultaneous Localization and Mapping), utilisée pour la navigation des robots à l'intérieur d'un bâtiment, la transformation 3D est calculée sans avoir recours à une carte préétablie, mais en exploitant des propriétés invariantes des caractéristiques extraites de l'environnement. Nous proposons une approche par "division pour régner" (divide and conquer, D&C) qui simplifie les tâches d'association des repères (data association, DA) et de reconstruction du mouvement
Automated localization is an important functionality for Mobile Mapping Systems (MMS). This thesis presents complimentary solutions to the current localization methods used in a terrestrial MMS, using GPS receivers and Inertial Measurement Units (IMU). A smoothing-based post-mission processing improves the 3D maps generated by MMS. However, this approach is still insufficient, when exposed to slowly varying input sensor errors. The thesis proposes an alternative localization method using 2D laser scanners. The proposed laser odometry approach uses planar landmarks in manmade environments, to detect and compute the transformation of the mobile platform. Unlike Simultaneous Localization and Mapping (SLAM) technique, used in indoor robotic navigation, the relative 3D transformation is computed without using a map, but by exploiting the time invariant properties of the extracted features. A new Divide & Conquer (D&C) approach is proposed to simplify the computation, involving both transformation and Data Association

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Vanek, Raymond, and Sophie Walker. "A study of inter-generational activities in structured environments for seniors." CSUSB ScholarWorks, 1996. https://scholarworks.lib.csusb.edu/etd-project/1236.

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This survey research project explored different factors influencing the desire of seniors living in structured residential centers to have inter-generational activities with children from their communities.

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Gaugaz, Julien [Verfasser]. "Schema-agnostic entity retrieval in highly heterogeneous semi-structured environments / Julien Gaugaz." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1077019424/34.

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Fahlström, Therése. "Distance and angle measurement in water and air for visual inspections in radioactive environments." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-310672.

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Ahlberg Cameras is a company that manufactures advanced camera systems and inspection equipment for the nuclear industry. Every nuclear plant shuts down their reactors approximately every 18 months to perform visual inspections of the vessels to find cracks and other damage. The company has received a request from Electric Power Research Institute (EPRI) to develop a distance meter that will operate in the reactor vessel, placed in an inspection camera. The device should measure the distance between the camera and an object, and the angle between them. The measurement is performed in air and underwater and the device has therefore a requirement to be waterproof and radiation tolerant. This thesis work has studied different possible technologies and technically excluded the ones that are not suitable for the intended application. A large part of the study has been about whether sound or light is a good enough source to use in the different technologies. The study has excluded to use sound mainly because the reflection back to the receiver at large angles becomes too weak. The choice of technology stands between structured light and a self-designed trigonometry technology, both using lasers. Tests have been made to determine if laser light underwater can be observed by the camera and the results indicates that lasers work well enough for this kind of application. Further in-depth studies into the sources of errors and measurement accuracy are needed for determining which of the two technologies is the most suitable.

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Kühn, Marco Julian [Verfasser]. "Screw thread motility of polarly flagellated bacteria enhances movement through structured environments / Marco Julian Kühn." Gießen : Universitätsbibliothek, 2019. http://d-nb.info/1192215060/34.

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Gonzalez, Villela Victor J. "Research on a semiautonomous mobile robot for loosely structured environments focused on transporting mail trolleys." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/34940.

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In this thesis is presented a novel approach to model, control, and planning the motion of a nonholonomic wheeled mobile robot that applies stable pushes and pulls to a nonholonomic cart (York mail trolley) in a loosely structured environment. The method is based on grasping and ungrasping the nonholonomic cart, as a result, the robot changes its kinematics properties. In consequence, two robot configurations are produced by the task of grasping and ungrasping the load, they are: the single-robot configuration and the robot-trolley configuration. Furthermore, in order to comply with the general planar motion law of rigid bodies and the kinematic constraints imposed by the robot wheels for each configuration, the robot has been provided with two motorized steerable wheels in order to have a flexible platform able to adapt to these restrictions.

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Trevor, Alexander J. B. "Semantic mapping for service robots: building and using maps for mobile manipulators in semi-structured environments." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53583.

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Although much progress has been made in the field of robotic mapping, many challenges remain including: efficient semantic segmentation using RGB-D sensors, map representations that include complex features (structures and objects), and interfaces for interactive annotation of maps. This thesis addresses how prior knowledge of semi-structured human environments can be leveraged to improve segmentation, mapping, and semantic annotation of maps. We present an organized connected component approach for segmenting RGB-D data into planes and clusters. These segments serve as input to our mapping approach that utilizes them as planar landmarks and object landmarks for Simultaneous Localization and Mapping (SLAM), providing necessary information for service robot tasks and improving data association and loop closure. These features are meaningful to humans, enabling annotation of mapped features to establish common ground and simplifying tasking. A modular, open-source software framework, the OmniMapper, is also presented that allows a number of different sensors and features to be combined to generate a combined map representation, and enabling easy addition of new feature types.

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de, Bock Hendrik Pieter Jacobus. "Design and Experimental Validation of a Micro-Nano structured Thermal Ground Plane for high-g environments." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367937275.

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Le, Andrew Phong. "Design patterns for online learning environments: A structured approach for operationalizing and sharing theory-based design knowledge." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1439424.

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Schlechtriemen, Julian David [Verfasser], and Klaus-Dieter [Gutachter] Kuhnert. "Probabilistic freespace prediction in structured traffic environments for trajectory planning / Julian David Schlechtriemen ; Gutachter: Klaus-Dieter Kuhnert." Siegen : Universitätsbibliothek der Universität Siegen, 2021. http://d-nb.info/1235224082/34.

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Pratt, Justin M. "Undergraduate Students Teaching Chemistry in Informal Environments: Investigating Chemistry Outreach Practices and Conceptual Understanding." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami154203032638329.

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Pita, Ricardo Miguel Miguéns Cardoso Cadete. "Persistence and coexistence of spatially structured populations in heterogeneous environments : the case of Cabrera and water voles in mediterranean farmland." Doctoral thesis, Universidade de Évora, 2010. http://hdl.handle.net/10174/22819.

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Esta tese avalia o modo como as populações animais respondem à heterogeneidade ambiental analisando a sua importância para a persistência do rato de Cabrera (RC) em paisagens fragmentadas, e para a coexistência desta espécie com o potencial competidor dominante rato- de-água (RA). A ocorrência do RC foi parcialmente explicada pelo tamanho e isolamento das parcelas de habitat, de acordo com a teoria das metapopulações, embora a persistência dos fragmentos e a composição da matriz sejam também criticas para a persistência da espécie. A coexistência de RC e RA pode ser explicada pela segregação espacial dentro das parcelas de habitat, provavelmente devido à diferenciação do micro-habitat a múltiplas escalas. A partição temporal a escalas finas poderá igualmente favorecer a coexistência, embora provavelmente como um mecanismo secundário. Globalmente, este estudo sugere que a análise da heterogeneidade a múltiplas escalas será essencial para avaliar a persistência e coexistência de espécies ecologicamente semelhantes. ⓿⓿⓿ ABSTRACT: This thesis investigates how animal populations respond to environmental heterogeneity, by analysing its importance for the persistence of Cabrera voles in highly fragmented landscapes, and for the coexistence of this species with a potentially dominant competitor (the water vole). The occurrence of Cabrera voles was partly explained by the patch size and isolation paradigms of metapopulation theory, though patch persistence and the composition of the intervening matrix also appeared to be critical for species persistence. Coexistence of Cabrera and water voles could be reasonably explained by spatial segregation within patches, probably reflecting microhabitat differentiation across multiple spatial scales. There was also some time partitioning between vole species, but this was probably a secondary mechanism favoring their coexistence. Overall, results suggest that measurements on heterogeneity at multiple spatial and temporal scales may be essential to properly assess the persistence and coexistence of ecologically similar species.

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Paul, Ruma R. "An Empirical Study of the Global Behavior of Structured Overlay Networks as Complex Systems." Licentiate thesis, KTH, Programvaruteknik och Datorsystem, SCS, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174048.

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Distributed applications built on top of Structured Overlay Networks (SONs) operate based on certain self-* behaviors of the underlying Peer-to-Peer network. Among those, self-organization and self-healing are the two most prominent and assumed properties. The operating environment of distributed systems continues to be more inhospitable with the advance and demand of new technologies; for example in case of mobile and ad hoc networks Churn (node turnover) can be extremely high due to node mobility, frequent disconnects/reconnects and configuration changes. Also, in such dynamic environments, the system may face high Churn (node turnover) and Network partition in a frequent manner. The situation becomes worse if the self-healing behavior of underlying SON is not complete and well defined. This implies the following non-trivial questions: Can the maintenance mechanism of a SON heal the damage to the structure due to harshness of the operating environment and reverse it back? What are the pre-conditions; in other words, what properties the healing mechanism should possess in order to achieve reversibility against stressful environments? Existing literature lacks such assessment and verification study of the self-healing property of a SON. In this thesis, we investigate both the behavior and design of a system that operate in inhospitable environments. This work is relevant to systems with both peaks of high stress (e.g. partitions, churn, network dynamicity etc.) and continuous high stress. We evaluate existing overlay maintenance strategies, namely Correction-on-Change, Correction-on-Use, Periodic Stabilization, and Ring Merge. We define the reversibility property of a system as its ability to repair itself to its original state. We propose a new strategy, called Knowledge Base, to improve conditions for reversibility against inhospitable environments. By means of simulations, we demonstrate reversibility for overlay networks with high levels of partition and churn. We make general conclusions about the ability of the maintenance strategies to achieve reversibility. Identification of Phase Transitions in a SON can provide useful information about the properties of each state of the system. Also, this enables to find the critical points in the operating space and parameters influencing them. The applications running on top of the SON can potentially utilize this knowledge to adapt its operation accordingly in different system states. In this thesis, a representative ring-based SON, namely Beernet is chosen and extended to achieve reversibility. The resulting overlay, Beernet++ exhibits reversible phase transitions under churn. We analyze the critical points observed during such transitions. We present the behavior of Beernet++ for high level of churn and network partitioning, along with their interaction.

QC 20150929

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Wheeler, Sonya. "A structured technique for applying risk based internal auditing in information technology environments : (with specific reference to llA RBIA, King Report and CobiT) /." Link to the online version, 2005. http://hdl.handle.net/10019/1310.

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Wheeler, Sonya. "A structured technique for applying Risk Based Internal Auditing in information technology environments (with specific reference to IIA RBIA, King Report and CobiT)." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1016.

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Thesis (M.Comm. (Accountancy))--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: A technique that may be used to incorporate Risk Based Internal Auditing (RBIA) in the IT environment is to follow annual audit planning methodology steps. The IT infrastructure elements are linked to the business processes which they support. Their ranking are based on the risk assessments of the business process, the business process priority, the dependency of the business process on IT and the IT infrastructure element’s own risk assessment. CobiT is used as an auditing method, i.e. best practice guidance to audit against.

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Van, Wyk Frans-Pieter. "Simutaneous real-time object recognition and pose estimation for artificial systems operating in dynamic environments." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/33323.

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Recent advances in technology have increased awareness of the necessity for automated systems in people’s everyday lives. Artificial systems are more frequently being introduced into environments previously thought to be too perilous for humans to operate in. Some robots can be used to extract potentially hazardous materials from sites inaccessible to humans, while others are being developed to aid humans with laborious tasks. A crucial aspect of all artificial systems is the manner in which they interact with their immediate surroundings. Developing such a deceivingly simply aspect has proven to be significantly challenging, as it not only entails the methods through which the system perceives its environment, but also its ability to perform critical tasks. These undertakings often involve the coordination of numerous subsystems, each performing its own complex duty. To complicate matters further, it is nowadays becoming increasingly important for these artificial systems to be able to perform their tasks in real-time. The task of object recognition is typically described as the process of retrieving the object in a database that is most similar to an unknown, or query, object. Pose estimation, on the other hand, involves estimating the position and orientation of an object in three-dimensional space, as seen from an observer’s viewpoint. These two tasks are regarded as vital to many computer vision techniques and regularly serve as input to more complex perception algorithms. An approach is presented which regards the object recognition and pose estimation procedures as mutually dependent. The core idea is that dissimilar objects might appear similar when observed from certain viewpoints. A feature-based conceptualisation, which makes use of a database, is implemented and used to perform simultaneous object recognition and pose estimation. The design incorporates data compression techniques, originally suggested by the image-processing community, to facilitate fast processing of large databases. System performance is quantified primarily on object recognition, pose estimation and execution time characteristics. These aspects are investigated under ideal conditions by exploiting three-dimensional models of relevant objects. The performance of the system is also analysed for practical scenarios by acquiring input data from a structured light implementation, which resembles that obtained from many commercial range scanners. Practical experiments indicate that the system was capable of performing simultaneous object recognition and pose estimation in approximately 230 ms once a novel object has been sensed. An average object recognition accuracy of approximately 73% was achieved. The pose estimation results were reasonable but prompted further research. The results are comparable to what has been achieved using other suggested approaches such as Viewpoint Feature Histograms and Spin Images.
Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
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Winner-Leoni, Melissa D. "An Investigation of the Security Designs of a Structured Query Language (SQL) Database and its Middleware Application and their Secure Implementation within Thinclient Environments." [Denver, Colo.] : Regis University, 2008. http://165.236.235.140/lib/MWinnerLeoni2008.pdf.

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Van, Noordwyk Arina. "Quantifying the sustainability of the built environment : the development of a complete environmental life cycle assessment tool." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96923.

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Thesis (MEng)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Sustainability is becoming an increasingly important aspect in all facets of engineering. It is in particular an important consideration in the structural engineering industry, due to the prominence of the negative impact this industry has on the environment, both on a national and international scale. The problem, however, is that sustainability is a mostly unknown and highly debated topic. It is not only difficult to quantify, but even difficult just to define. In the field of structural engineering it is an especially difficult task to consider sustainability. It is still a very new field of research and difficult to apply. It is therefore important that continued research be done in order for there to be a better understanding of how sustainability should be considered and applied in the context of structures. In an attempt to assess the environmental impact of building structures, there are two basic approaches that are followed. The first, the application-oriented method, is a simple, points-based system. The second, the analysis-oriented method, makes use of detailed indices and factors to quantify the impact. This study aims to develop an analysis-oriented method, specifically designed for the complete life cycle of buildings in the South African environment. This is accomplished by continuing the work that was started by Brewis (2011), and continued by Brits (2012). Brewis developed the approach for the pre-use phase, while Brits developed the approach for the end-of-life phase. Both focussed their application on low-cost housing development. However, the approach is defined for the use of the analysis of a building envelope. The details of developing the environmental life cycle assessment (LCA), as well as the approaches for the pre-use phase and the end-of life phase are discussed in Chapter 3. The study develops the use phase of the proposed environmental life cycle assessment for buildings in Chapter 4. It discusses in detail the two main components of the use phase, namely maintenance and operation. While maintenance is concerned with the replacement of building materials in the structure, the operation component is concerned with the energy needs during the use phase. It is determined that the energy use that is directly related to the building envelope is the energy required for the space heating and cooling of the building. This is due to the fact that the thermal properties of the building envelope influence the thermal environment within the building, and thereby impact the use of energy to regulate that thermal environment. In order to make the most use of both of these components within the application of the proposed LCA, it was decided to model a residential building structure that uses consistent energy to regulate the thermal environment within the structure. However, it is not only the objective to use the proposed LCA as an assessment tool, but also as a comparative and optimisation tool. Therefore one component, the external walls, was selected as a variable component. This component was varied to form a total of nine different buildings. These nine buildings were then used in a comparative study in order to try to determine an optimum choice of external walling system, based on the results of the environmental impacts determined in the LCA. It is also used to try to explain exactly how and to what extent the external walling system contributes to the environmental impact, and what useful application value we can gain from this knowledge. The results showed that a minor increase in the materials impact (due to attempts to improve the thermal capacity of the external walls) were in most cases countered by a decrease in the energy impact, which in seven of the eight alternative external walling systems led to a net decrease in environmental impact (EI) categories one to four. It was also found that with the increase of the R-value of the external walling systems, the environmental impact of the building steadily decreased, in terms of four of the five impact categories. The only exception to these trends was found in the fifth impact category: waste generation. The reason for this is the fact that energy impact in this environmental impact category is negligible, and therefore does not contribute much to the net change in environmental impact.
AFRIKAANSE OPSOMMING: Die belangrikheid van volhoubaarheid neem al hoe meer toe in alle aspekte van ingenieurswese. In die industrie van struktuuringenieurswese is dit van besonderse belang as gevolg van die prominente negatiewe impak van hierdie industrie op die omgewing, op beide ’n nasionale en internasionale skaal. Die probleem is egter dat volhoubaarheid nog meestal gesien word as ŉ onderwerp wat onbekend en hoogs debatteerbaar is. Dit is nie net moeilik om te kwantifiseer nie, maar selfs moeilik om dit net te definieer. In struktuuringenieurswese is dit veral ŉ moeilike taak om volhoubaarheid in ag te neem. Dit is nog ŉ baie jong studieveld wat moeilik is om toe te pas. Dit is dus van uiterse belang dat verdere navorsing gedoen word sodat daar ŉ beter begrip kan wees van hoe volhoubaarheid op die lewensiklus van strukture toegepas kan word. In 'n poging om die omgewingsimpak van die geboustrukture te evalueer, is daar twee basiese benaderings wat gevolg kan word. Die eerste, die toepassingsgeoriënteerde metode, is 'n eenvoudige, punte-gebaseerde stelsel. Die tweede, die analise-georiënteerde metode maak gebruik van gedetailleerde indekse en faktore om die omgewingsimpak te kwantifiseer. Hierdie studie beoog om 'n analise-georiënteerde metode te ontwikkel, wat spesifiek ontwerp is vir die analise van die volledige lewensiklus van geboue in die Suid-Afrikaanse omgewing. Dit word gedoen deur die voortsetting van die werk wat begin is deur Brewis (2011), en voortgesit is deur Brits (2012). Brewis het die benadering vir die eerste fase (voor-gebruik) ontwikkel, terwyl Brits die benadering vir die finale fase (einde-van-lewe) ontwikkel het. Beide het die fokus van hul toepassings geplaas op lae-koste behuising. Die benaderings is egter gedefinieer vir die algemene analise van ŉ gebou se raamwerk. Die besonderhede van die ontwikkeling van die omgewingslewensiklus analise (OLA), asook die benaderings vir die eerste en finale fases, word in Hoofstuk 3 bespreek. Die studie ontwikkel die gebruiksfase van die voorgestelde omgewingslewensiklus analise vir geboue in Hoofstuk 4. Dit bespreek die twee hoofkomponente van die gebruiksfase, naamlik die instandhouding en bedryf. Terwyl instandhouding gemoeid is met die vervanging van boumateriale in die struktuur, is die bedryfskomponent gemoeid met die energie behoeftes tydens die gebruiksfase. Dit word bepaal dat die energie verbruik wat ŉ direkte verband het met die gebou se raamwerk, die energie is wat nodig is vir die verhitting en verkoeling van die gebou. Dit is te danke aan die feit dat die termiese eienskappe van die gebou se raamwerk die termiese omgewing binne die gebou beïnvloed, en sodoende 'n impak het op die energie wat benodig word om die temperatuur te reguleer. In ŉ poging om die spektrum van die voorgestelde OLA ten volle te benut, is dit besluit om die toepassing daarvan te illustreer op 'n residensiële gebou wat van konsekwente energieverbruik gebruik maak om die termiese omgewing binne die gebou te reguleer. Dit is egter nie net die doel om die voorgestelde OLA te gebruik as 'n assesseringsinstrument nie, maar ook om die OLA se funksie as ’n vergelykende en optimaliseringshulpmiddel te illustreer. Dus is een komponent, die eksterne mure, gekies as 'n veranderlike komponent. Hierdie komponent is gewissel om 'n totaal van nege verskillende geboue te vorm. Hierdie nege geboue is gebruik in 'n vergelykende studie in 'n poging om 'n optimale keuse van eksterne mure te bepaal, gebaseer op die resultate van die omgewingsimpak wat in die OLA te bepaal is. Dit word ook gebruik om te probeer om te verduidelik presies hoe en tot watter mate die eksterne mure bydra by tot die omgewingsimpak, en watter nuttige toepassingswaarde geput kan word uit hierdie kennis. Die resultate het getoon dat 'n toename in die materiaal impak (weens pogings om die termiese kapasiteit van die eksterne mure te verbeter) in die meeste gevalle teengewerk is deur 'n afname in die energie impak. In sewe van die agt alternatiewe eksterne muurstelsels het dit gelei tot 'n netto afname in omgewingsimpak vir kategorieë een tot vier. Dit is ook gevind dat die omgewingsimpak van die gebou stelselmatig gedaal het met die toename van die Rwaarde van die eksterne muurstelsels, ook in terme van kategorieë een tot vier. Die enigste uitsondering op hierdie tendense is gevind in die vyfde impak kategorie: die afval wat gegenereer word. Die feit dat die effek van energie verbruik gering is in hierdie omgewingsimpak kategorie, lei tot die feit dat dit nie veel bydra tot die netto verandering in die omgewingsimpak nie.

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38

Greggains, A. "A structured computing environment." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304375.

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39

Read, Shari P. "An exploration of the structure and structural consequences of environmental concern." Thesis, Read, Shari P. (2002) An exploration of the structure and structural consequences of environmental concern. PhD thesis, Murdoch University, 2002. https://researchrepository.murdoch.edu.au/id/eprint/50459/.

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This thesis explores the psychological structure of environmental concern. It deals with the possibility of there being two different types of environmental concern; environmental/optimal use concern and ecological/preservationist concern. The thesis is unique in its assertion that the difference between the two types of concern exists as a structural separation within the social cognition of individuals. The thesis is founded on the idea that environmental attitudes are embedded within socio-political cognition more so than attitudes concerned primarily with ecology. The first part of the thesis establishes the empirical evidence supporting the existence of two separate types of environmental concern and demonstrates their differential relationships with socio-political attitudes as a representation of the Dominant Social Paradigm. Specifically, the first study focuses on the relationship between environmental attitudes, ecological attitudes, socio-political attitudes and beliefs about money. A cross-sectional survey of first year students at Murdoch University revealed that socio-political attitudes and beliefs about money each had a predictive relationship with environmental attitudes, while no such relationships were present for ecological attitudes. These results were replicated in a subsequent study that also explored associations between environmental attitudes and knowledge. The second part of the thesis concentrates on the differential effects of priming people to either their environmental attitudes or their ecological attitudes to further test the separation of these cognitive structures. Study Three was designed to manipulate responses to environmentally relevant word stimuli. The results supported the separability of the two types of environmental concern, revealing environmental attitudes, but not ecological attitudes, to be embedded within the network of socio-political attitudes. Results from Study Four showed that spontaneous word associations to the concepts, ‘environmental protection’ and ‘economic development’, differ significantly when participants are primed to their environmental attitudes as opposed to their ecological attitudes. This study also explores the structure of each of these types of environmental concern separately to validate the respective conceptualizations of ‘environmental’ and ‘ecological’ concern. Findings suggest that environmental concern is strongly associated with economic and political constructs while ecological attitudes are specifically ‘green’. Chapter eight presents Study Five that further explores the structure of environmental and ecological attitudes. The study specifically examines the effects of priming on attitude accessibility and extremity. Findings reveal that the relative importance of an attitude object is a primary predictor of the extremity of environmental attitudes. The results also show that evaluations of environmental stimuli can be influenced by increasing the salience of ecological concern. The thesis then extends to consider the behavioural consequences of the structural separability of environmental and ecological attitudes. Three environmental dilemmas were used in Study Six to examine the effects of priming on behavioural intentions. Chapter nine presents findings which illustrate, that although the primes had little influence over decisions about the dilemmas, a manipulation of the economic context of the dilemma had a significant effect on participants’ responses. Chapter ten provides an integration and discussion of the implications of the structural separability of environmental and ecological attitudes. It also reviews the findings presented within the thesis that demonstrate the prevailing dominance of the Dominant Social Paradigm. It is concluded that the thesis is successful in its endeavor to provide empirical support for the hypothesis that environmentalism and ecologism represent two distinct forms of concern for the natural environment.

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Shafieezadeh, Abdollah. "Application Of Structural Control For Civil Engineering Structures." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/142.

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This study presents the application of control methods in seismic mitigation of structural responses. The study consists of two parts. In the first section, fractional order filters are utilized to enhance the performance of the conventional LQR method for optimal robust control of a simple civil structure. The introduced filters modify the state variables fed back to the constant gain controller. Four combinations of fractional order filter and LQR are considered and optimized based on a new performance criterion defined in the paper. Introducing fractional order filters is shown to improve the results considerably for both the artificially generated ground motions and previously recorded earthquake data. In the second part, frequency dependent filters are introduced to improve the effectiveness of active control systems designed to mitigate the seismic response of large scale civil structures. These filters are introduced as band pass pre-filters to the optimally designed H2/LQG controller to reduce the maximum singular value response of input-output transfer matrices over a defined frequency range. Furthermore, a structured uncertainty model is proposed to evaluate robustness of stability and performance considering nonlinear force-deformation behavior of structures. The proposed perturbation model characterizes variations in the stiffness matrix more accurately, thereby reducing overconservatism in the estimated destabilizing perturbations. The aforementioned techniques are applied to the nonlinear SAC three story steel building. Numerical results indicate that introducing filters can enhance the performance of the system in almost all response measures, while preserving robustness of stability and performance.

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Perry, Michael John. "Discomfort glare, light scatter, and scene structure." Thesis, Open University, 1995. http://oro.open.ac.uk/57561/.

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Since the start of the Industrial Revolution there has been a general improvement in working conditions. As part of this process, light in the work place was recognised as an important environmental factor. In the early years of the 20th century it was also recognised that in providing adequate lighting for a particular working environment, there was a need to avoid the potential negative effects of too much, or inappropriately distributed, light. One of the negative effects of light in the work place was glare. Holladay (Holladay, (1926)) attributed the negative effects of glare to impairment of vision caused by light scatter. Stiles (Stiles, (1929)) refuted Holladay's case by arguing that only a small proportion of the reduction in task visibility could be attributed to light scatter effects (where task visibility is a measure of how far above the visual threshold a task's contrast is). Stiles distinguished disability glare, a light scatter effect, from discomfort glare which was glare that could not be attributed to light scatter. The distinction made by Stiles resulted in the separate development of discomfort and disability glare models. Very few, if any, studies since Stiles have re-evaluated the potential association between subjectively rated discomfort glare, and physically based disability glare. In the study reported here, subjects were asked to set the appearance of a 2° glare source so that it appeared at the Borderline between Comfort and Discomfort, or BCD (Guth, (1963)). Each subject's visual threshold for a 4 cycle per degree spatial grating was measured under BCD and control conditions, and a comparison made to assess if light scatter effects from the glare source influenced threshold contrast, C_th. The results of the study indicate that C_th, can be lower in the presence of the glare source set to BCD. This anomaly may be explained by improvement in image quality caused by the glare source driving the pupil to a smaller diameter. More significantly, there was found to be a strong correlation between subjective BCD settings and age, and also between BCD settings and control condition C_th. Both of these results suggest an influence of light scatter on BCD settings of discomfort glare. This conclusion was further supported by the fitting to the data of the independently reported stray light function of Ijspeert et al (Ijspeert et al, (1990)). Thus the results strongly suggest a correlation between subjective BCD settings of a glare source and light scatter function. A conclusion that substantially weakens Stiles' argument that discomfort glare is not dependent on light scatter effects. Using the results of the study, a new threshold type model for assessing discomfort glare is proposed, which explicitly includes age as a parameter. However, much variance remains to be explained in the glare data. Therefore, a second theme investigated in the dissertation is the possible association between scene visual structure and visual discomfort. The results of this study indicate that there is a small but significant difference in the image structure of natural and man made environments. This difference may contribute to visual discomfort, but will require further investigation.

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Norman, Michael John. "SSDE : structured software development environment." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/15899.

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Bibliography: pages 219-230.
Software engineers have identified many problem areas regarding the development of software. There is a need for improving system and program quality at design level, ensuring that design costs remain within the budget, and increasing the productivity of designers. Structured Software Development Environment (SSDE) provides the system designer with an interactive menu-driven environment, and a framework within which he can conveniently express and manipulate his proposed solution. This representation is in terms of both a conceptual model and a detailed software logic definition. Thus SSDE provides tools for both high-level (or logical) and low-level (or physical) design. It allows a user to follow his own preferred methodology rather than restricting him to one specific strategy. SSDE builds and maintains databases that record all design decisions. It provides the system designer with a mechanism whereby systems can easily be modified and new systems can evolve from similar existing systems. There are several auxiliary facilities as productivity aids. SSDE generates PASCAL code for low-level design constructs, ·full documentation of both the high- and low-level designs for inclusion in the project file, as well as a skeleton manual. The system was evaluated by a number of independent users. This exercise clearly demonstrated its success as an aid in expressing, understanding, manipulating and solving software development problems.

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Johnson, Brian. "Can Education Improve the Environment? Applying the Pressure-State-Response Environmental Indicator Framework to Environmental Education Program Outcomes." Antioch University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=antioch1375367966.

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Ogletree, Roy Duncan. "Rules to a structured urban environment." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/22369.

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Aydemir, Alper. "Exploiting structure in man-made environments." Doctoral thesis, KTH, Datorseende och robotik, CVAP, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104410.

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Robots are envisioned to take on jobs that are dirty, dangerous and dull, the three D's of robotics. With this mission, robotic technology today is ubiquitous on the factory floor. However, the same level of success has not occurred when it comes to robots that operate in everyday living spaces, such as homes and offices. A big part of this is attributed to domestic environments being complex and unstructured as opposed to factory settings which can be set up and precisely known in advance. In this thesis we challenge the point of view which regards man-made environments as unstructured and that robots should operate without prior assumptions about the world. Instead, we argue that robots should make use of the inherent structure of everyday living spaces across various scales and applications, in the form of contextual and prior information, and that doing so can improve the performance of robotic tasks. To investigate this premise, we start by attempting to solve a hard and realistic problem, active visual search. The particular scenario considered is that of a mobile robot tasked with finding an object on an entire unexplored building floor. We show that a search strategy which exploits the structure of indoor environments offers significant improvements on state of the art and is comparable to humans in terms of search performance. Based on the work on active visual search, we present two specific ways of making use of the structure of space. First, we propose to use the local 3D geometry as a strong indicator of objects in indoor scenes. By learning a 3D context model for various object categories, we demonstrate a method that can reliably predict the location of objects. Second, we turn our attention to predicting what lies in the unexplored part of the environment at the scale of rooms and building floors. By analyzing a large dataset, we propose that indoor environments can be thought of as being composed out of frequently occurring functional subparts. Utilizing these, we present a method that can make informed predictions about the unknown part of a given indoor environment. The ideas presented in this thesis explore various sides of the same idea: modeling and exploiting the structure inherent in indoor environments for the sake of improving robot's performance on various applications. We believe that in addition to contributing some answers, the work presented in this thesis will generate additional, fruitful questions.

QC 20121105

CogX

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Hakl, Henri. "Structure-from-motion for enclosed environments." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019.1/1195.

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Park, Gyuhae. "Assessing Structural Integrity using Mechatronic Impedance Transducers with Applications in Extreme Environments." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27719.

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This research reviews and extends the impedance-based structural health monitoring technique in order to detect and identify structural damage on various complex structures. The basic principle behind this technique is to apply high frequency structural excitations (typically higher than 30 kHz) through the surface-bonded piezoelectric transducers, and measure the impedance of structures by monitoring the current and voltage applied to the transducers. Changes in impedance indicate changes in the structure, which in turn can indicate that damage has occurred. Several case studies, including a pipeline structure, a composite reinforced aluminum plate, a precision part (gear), a quarter-scale bridge section, and a steel pipe header, demonstrate how this technique can be used to detect damage in real-time. A method to process impedance measurements to prevent significant temperature and boundary condition changes registering as damage has been developed and implemented. Furthermore, the feasibility of using the technique for high temperature structures and for condition monitoring of critical facilities subjected to a severe natural disaster has been investigated. While the impedance-based structural health monitoring technique indicates qualitatively that damage has occurred, more information on the nature of damage is necessary for remote structures. In this research, two different damage identification schemes have been combined with the impedance method in order to quantitatively assess the state of structures. One is based on a wave propagation modeling, and the other is the use of artificial neural networks. A newly developed wave propagation model has been developed and combined with the impedance method in order to estimate the severity of damage. Numerical and experimental investigations on 1-dimensional structures were presented to illustrate the effectiveness of the combined approach. Furthermore, to avoid the complexity introduced by conventional computational methods in high frequency ranges, multiple sets of artificial neural networks were integrated with the impedance-based health monitoring technique. By incorporating neural network features, the technique is able to detect damage in its early stage and to determine the severity of damage without prior knowledge of the model of structures. The dissertation concludes with experimental examples, investigations on a quarter-scale steel bridge section and a space truss structure, in order to verify the performance of the proposed methodology.
Ph. D.

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Uzun, Murat. "Learning Structures : fusing deconvolution-based seismic interferometry with Bayesian inference for structural health assessment." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115801.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 129-135).
Monitoring vibration responses of civil structures is crucial to the assessment of their health status and reliability against natural hazards. In this study, we present a two-step computational methodology for structural identification and damage detection via fusing the concepts of seismic interferometry and Bayesian inference. Firstly, a deconvolution-based seismic interferometry approach is employed to obtain the wave-forms that represent the impulse response functions (IRFs) with respect to a reference excitation source. Using the deconvolved waveforms, key structural characteristics that correspond to the current state of the structure (e.g., shear wave velocity) can be extracted. Changes in these features can be used as a qualitative damage metric (e.g., to determine if the structure is damaged). We study the following two different damage detection methods that utilize shear wave velocity variations: (1) the arrival picking method (APM) and (2) the stretching method (SM). Secondly, a hierarchical Bayesian inference framework is employed to update a finite element model minimizing the gap between the predicted and the measured time histories of the IRFs. We employ a sequential Markov Chain Monte Carlo (MCMC) sampling to obtain a baseline structural model. Through the comparison of the model parameter distributions with the baseline information, we show that the damage localization and quantification is possible. We initially test our procedure utilizing the synthetic records of a 10-story shear type building. Despite high noise contamination, identification results realized through our approach for both stiffness and damping parameters show good correlation with their true values. For further deployment, we analyze the shake-table experiment dataset that contains various damage scenarios. We show that the variations in the shear wave velocity can be used for qualitative/quick damage detection, and that the velocity reduction is more evident for the more severely damaged states. We then update our FEM by the presented Bayesian learning framework by utilizing the extracted IRFs of the experimental structure. Induced damage, i.e. bolt-loosening on the first floor, affects the posterior distributions quite noticeably. Finally, the structural damage detection problem is addressed by studying an experimental data set of full-scale seven story building slice, that was progressively damaged via previously recorded historical earthquake records utilizing the Network for Earthquake Engineering Simulations (NEES) shake-table. Our results indicate that the developed framework is promising for monitoring structural systems. It allows for non-invasive determination of structural parameters.
by Murat Uzun.
S.M.

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Ma, Mo. "Navigation using one camera in structured environment /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20MA.

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Kayser, Matthew R. (Matthew Russell). "RM methods for multiple fare structure environments." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44681.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.
Includes bibliographical references (p. 110-115).
The rapid growth of Low Cost Carriers (LCC) and their simplified fare structures has created "semi-restricted" fare structures where lower classes are undifferentiated except for price, while higher fare classes are still differentiated by various advance purchase and booking restrictions. The problem this causes is two-fold: first, traditional revenue management systems, which operate based on the assumption of demand independence, will see demand "spiral down" into the lowest booking classes as passengers will buy the lowest available fare in the absence of fare restrictions. Second, airlines must maximize network revenues across two different fare structures, a more-restricted structure used on markets without an LCC presence, and the semirestricted structure for markets where LCC competition exists. This thesis describes methods of dealing with these two problems: Hybrid Forecasting (HF), which forecasts "product-oriented" demand using traditional forecasting methods while simultaneously forecasting "price-oriented" demand for those passengers who will buy the lowest available fare, and Fare Adjustment (FA), which is used at the booking limit optimizer level to account for the sell-up potential of passengers (probability a passenger will book in a higher class if his original booking class is denied). Fare Adjustment allows the airline to deal with multiple fare structures separately. The goal of this thesis is to provide a comprehensive summary of results when an airline uses HF and FA simultaneously in two different multiple fare structure, competitive networks. An alternate Fare Adjustment formulation will also be introduced and tested in these competitive environments.
(cont.) Results from the Passenger Origin-Destination Simulator (PODS) demonstrate that in a more restrictive network, HF and FA used in conjunction with one another achieve revenue increases of approximately 2-4% above traditional forecasting methods. In an environment with a fully unrestricted fare structure for LCC markets, HF and FA together generate revenue gains of over 20% above traditional methods.
by Matthew R. Kayser.
S.M.

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Dissertations / Theses on the topic 'Structured Environments'

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