Masonry is one of the oldest forms of construction materials that is still in use today. However, construction practices in the modern age demand faster and more economical practices. Dry-stack masonry, or masonry that doesn't use mortar to bind the blocks together, is a unique system to make masonry more economical. Though several systems of dry-stack masonry have been suggested little to no data exists as most of these systems are patented. This research used dry-stacked normal weight concrete masonry units with an eccentrically placed reinforcement. The wall system is connected through a surface bond and lacks any geometric connection. Previously, research has been conducted on the wall system for its axial compressive capacity, but little information is known about its ability to withstand lateral forces such as earthquakes. Research was conducted on the wall system in order to determine the seismic parameters, including the force reduction factor, overstrength factor, and the displacement amplification factor. To determine these factors the guidelines from the Federal Emergency Management Agency (FEMA) Quantification of Building Seismic Performance Factors 2009 were followed. The guidelines are explicit that both experimental data and computer modeling are needed to quantify these parameters. Experimental data was obtained from a diagonal tension test, and an in-plane shear test. The diagonal tensions test provided preliminary values on the shear modulus and shear resistance. The in-plane shear test was of primary interest and what would be used to verify the computer model. Computer modeling of the wall system was accomplished with Vector 2. Initially the computer modeling was done to reproduce experimental data. Then, a parametric study was performed using the model to see what component of the wall most effected its capacity. This analysis showed that the surface bond was the component of the wall that most affects its capacity. Finally, the computer model was run through the FEMA Far-Field earthquake suite to gather data on the strength and ductility. Values of the force reduction factor, overstrength factor, and displacement amplification factor were determined based on the time history analysis and pushover analysis on the computer model.

Developers are often tasked with maintaining complex systems. Regardless of prior experience, there will inevitably be times in which they must interact with parts of the system with which they are unfamiliar. In such cases, recommendation systems may serve as a valuable tool to assist the developer in implementing a solution. Many recommendation systems in software engineering utilize the Stack Overflow knowledge-base as the basis of forming their recommendations. Traditionally, these systems have relied on the developer to explicitly invoke them, typically in the form of specifying a query. However, there may be cases in which the developer is in need of a recommendation but unaware that their need exists. A new class of recommendation systems deemed Behavior-Driven Recommendation Systems for Software Engineering seeks to address this issue by relying on developer behavior to determine when a recommendation is needed, and once such a determination is made, formulate a search query based on the software engineering task context. This thesis presents one such system, StackInTheFlow, a plug-in integrating into the IntelliJ family of Java IDEs. StackInTheFlow allows the user to intervi act with it as a traditional recommendation system, manually specifying queries and browsing returned Stack Overflow posts. However, it also provides facilities for detecting when the developer is in need of a recommendation, defined when the developer has encountered an error messages or a difficulty detection model based on indicators of developer progress is fired. Once such a determination has been made, a query formulation model constructed based on a periodic data dump of Stack Overflow posts will automatically form a query from the software engineering task context extracted from source code currently open within the IDE. StackInTheFlow also provides mechanisms to personalize, over time, the results displayed to a specific set of Stack Overflow tags based on the results previously selected by the user. The effectiveness of these mechanisms are examined and results based the collection of anonymous user logs and a small scale study are presented. Based on the results of these evaluations, it was found that some of the queries issued by the tool are effective, however there are limitations regarding the extraction of the appropriate context of the software engineering task yet to overcome.

Tailings (mining waste) disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. This creates large volumes of tailings, which must be handled and stored responsibly to avoid potential environmental catastrophes. The most common form of tailings storage facility is the impoundment, where tailings are contained within a basin, with beaches forming around the perimeter of the impoundment and a pond standing in the middle. A relatively new method of tailings storage is to create a 'stack', whereby the tailings solids form a large heap, with the discharge of tailings slurry from the apex of the heap. It is of significant value for mine operators and tailings engineers to be able to predict the shape of the beach that forms in either of these disposal scenarios. The key to being able to do this relies on a method of prediction of the beach slope. The aim of this work is to develop a method of tailings beach slope prediction for tailings slurries that are sub-aerially discharged from a pipe. In this thesis a literature review is undertaken, investigating existing methods for the prediction of tailings beach slopes. These methods are validated against relevant industrial and experimental data. Two separate phases of experimental work have taken place in an effort to investigate tailings deposition behaviour, one at mine sites and the other in a laboratory on a small scale. Three new tailings beach slope prediction models are presented; a simple empirical model enabling quick approximate predictions; an a priori tailings beach slope prediction model based on existing theories of open channel flow, sediment transport and rheology, which is more powerful due to the greater degree of theory in its foundation; and a new semi-empirical model that shares some of the theoretical aspects of the a priori model but offers better predictions due to its empirical calibration to the experimental data. The experimental results, along with 3 other independently collected sets of relevant industrial and experimental data, are used to validate the beach slope prediction models found in the literature, as well as the new beach slope models presented in this thesis. Statistical evaluation of the performance of all of these models is presented to enable comparison. Finally, a new beach shape model is presented for the three dimensional geometric forecasting of the beach surface of a tailings stack. Historic tailings discharge data is run through the beach shape model, and the shapes predicted by the model are compared with aerial survey data of a real tailings stack for validation of the shape model. This work not only presents a new method of tailings stack shape prediction, but also a plausible theory for explaining the concavity of tailings beaches. The stack shape model also has the potential to be developed further for the three dimensional modelling of tailings beaches formed in other types of storage facilities, such as impoundments or valleys.

<p>Internet is growing every day and this is leading to an address depletion of the current IPv4 addresses. A new version of IPv4, called IPv6, is the protocol for addressing computers that will deal with this problem. IPv4 and IPv6 are unfortunately not compatible with each other. IPv4 and IPv6 have to co-exist for a long time until IPv6 will be the dominant protocol.</p><p>The purpose of this thesis is to examine how a transition could be done or more correctly, how to deploy IPv6 in an already existing IPv4 network. After that part of the report a case study at the local Internet service provider Junet AB will be conducted. This case study will investigate an IPv6 deployment scenario for Junet AB.</p><p>A theoretical background has been written that describes some steps an Internet service provider has to go through to deploy IPv6. The case study was conducted after the theoretical background was written. The result of this report shows that a deployment of IPv6 in an IPv4 network is technically achievable. All the main components to maintain and use IPv6 in a commercial network exist.</p><p>The case study indicates that it is possible to deploy IPv6 in Junet AB´s network. IPv4 and IPv6 could be used in their network without any major effort. IPv6 have been around for many years now but have not had that break through many early adopters have hoped for. A lack of documentation and experience is an obstacle for a deployment of IPv6.One thing that remains now is to prove that there is a need for IPv6, but that is out of scope for this thesis.</p>

Fuel cells are one of most environmental friendly energy sources; they have many advantages and may be used in many applications from portable electronic devices to automotive components. Proton exchange membrane (PEM) fuel cells are one of most reliable fuel cells and have advantage such as rapid-startup and ease of operation. This dissertation focuses on PEM fuel cell stack optimization based on operation experimental research and numerical modeling study. This dissertation presents three major research activities and the obtained results by the Ph.D candidate. A novel stack architecture design is introduced in order to decrease mal-distribution and non-uniform output performance between individual cells in order to improve the stack performance. Novel stack architecture includes a novel external bifurcation flow distribution delivery system. One major issue of uniform distribution of reactants inside individual fuel cells and between fuel cells in a fuel cell stack is solved by the novel stack architecture design. A novel method for uniform flow distribution was proposed, in which multiple levels of flow channel bifurcations were considered to uniformly distribute a flow into 2ⁿ flow channels at the final stage, after n levels of bifurcation. Some detailed parameters such as the flow channel length and width at each level of bifurcation as well as the curvature of the turning area of flow channels were particularly investigated. Computational fluid dynamics (CFD) based analysis and experimental tests were conducted to study the effect of the flow channel bifurcation structure and dimensions on the flow distribution uniformity. Optimization design and factors influential to the flow distribution uniformity were also delineated through the study. The flow field with the novel flow distribution was then considered to be used in a cooling plate for large fuel cell stacks and a possible method for cooling electronic devices. Details of the heat transfer performance, particularly the temperature distributions, on the heating surface as well as the pressure losses in the operation were obtained. In the second part of the research, experimental testing, analytical modeling, and CFD methods were employed for the study and optimization of flow fields and flow channel geometry in order to improve fuel cell performance. Based on the experimental results, a serpentine flow field is chosen for CFD and modeling analysis. Serpentine flow channel optimization is based on the parametrical study of many combinations of total channel width and rib ratio. Modeling analysis and in-house made computational code was used to optimize the dimensions of flow channels and channel walls. It is recommended that cell channel design should use a small total channel width and rib ratio. Proton exchange membrane fuel cells were fabricated based on the optimization results. Experimental tests were conducted and the results coincided with the numerical analysis; therefore, small total width and rib ratio design could significantly improve the fuel cell performance. Three dimensional (3D) CFD simulations for various PEM fuel cells were conducted to investigate information such as water and reactants distribution. The direct simulation results of current density distribution proclaim how the channel design influences the performance. The final section of research is stack bipolar plate flow field optimization. Optimized channel geometries are applied to the serpentine channel design for the stack. This serpentine channel design evolved to parallel-serpentine channel and symmetric serpentine channel design. Experimental tests of the stacks using the above flow fields are compared to one another and the results recommend use of the novel symmetric serpentine flow channel for stack bipolar design to achieve best performance.

Organic electronics have received significant development in the last few decades. p- Type materials are much more in availability than n-type now. There are only a few examples of air-stable n-type materials. The design and synthesis of novel air-stable ntype materials is still a focus of research. Herein is described a study to evaluate the effectiveness of a novel electron-withdrawing group, composed of three electronwithdrawing groups connected in series, to impart material properties known to be favorable for obtaining air-stable n-types. The smaller acenes, naphthalene and anthracene, carrying these electron-withdrawing groups were prepared and studied by UV-Vis absorption spectroscopy and solution electrochemical measurements to estimate changes in frontier molecular orbital energies and single crystal X-ray diffraction to determine packing motif. These measurements suggest that the new materials could be promising as n-type semiconductors in organic field effect transistor (OFET) and as acceptors for organic photovoltaic (OPV) cells. The reasons are based on: (1) the close intermolecular contacts seen in X-ray crystal structures, some of them showing 3D faceto- face stack. (2) Electrochemical measurements indicate LUMO energy levels suitable for air-stable n-type materials.

Stack Overflow is the most popular Q&A website among software developers. As a platform for knowledge sharing and acquisition, the questions posted in Stack Over- flow usually contain a code snippet. Stack Overflow relies on users to properly tag the programming language of a question and assumes that the programming language of the snippets inside a question is the same as the tag of the question itself. In this the- sis, a classifier is proposed to predict the programming language of questions posted in Stack Overflow using Natural Language Processing (NLP) and Machine Learning (ML). The classifier achieves an accuracy of 91.1% in predicting the 24 most popular programming languages by combining features from the title, body and code snippets of the question. We also propose a classifier that only uses the title and body of the question and has an accuracy of 81.1%. Finally, we propose a classifier of code snip- pets only that achieves an accuracy of 77.7%.Thus, deploying ML techniques on the combination of text and code snippets of a question provides the best performance. These results demonstrate that it is possible to identify the programming language of a snippet of only a few lines of source code. We visualize the feature space of two programming languages Java and SQL in order to identify some properties of the information inside the questions corresponding to these languages. / Graduate

The teachers at Linköpings University are currently using an emailclient to handle the sharing of information between teachers involved ina course. This is inefficient due to the difficulty of sharing existinginformation with new course memebers, sharing new information with existingcourse members and finding specific information is an issue because of thelack of course separation. Some features, such as handing over a courseto a new leading teacher, are also lacking which makes course managementdifficult. To solve this issue, we have developed a web application whichfocuses on its usability and efficiency to make it easier for coursestaff to share course information. By performing usability and efficiencytests where test subjects used the new application as well as the oldemail system we established that the newly developed application with itsadditional features became an improvement over the old email system.

Internet is growing every day and this is leading to an address depletion of the current IPv4 addresses. A new version of IPv4, called IPv6, is the protocol for addressing computers that will deal with this problem. IPv4 and IPv6 are unfortunately not compatible with each other. IPv4 and IPv6 have to co-exist for a long time until IPv6 will be the dominant protocol. The purpose of this thesis is to examine how a transition could be done or more correctly, how to deploy IPv6 in an already existing IPv4 network. After that part of the report a case study at the local Internet service provider Junet AB will be conducted. This case study will investigate an IPv6 deployment scenario for Junet AB. A theoretical background has been written that describes some steps an Internet service provider has to go through to deploy IPv6. The case study was conducted after the theoretical background was written. The result of this report shows that a deployment of IPv6 in an IPv4 network is technically achievable. All the main components to maintain and use IPv6 in a commercial network exist. The case study indicates that it is possible to deploy IPv6 in Junet AB´s network. IPv4 and IPv6 could be used in their network without any major effort. IPv6 have been around for many years now but have not had that break through many early adopters have hoped for. A lack of documentation and experience is an obstacle for a deployment of IPv6.One thing that remains now is to prove that there is a need for IPv6, but that is out of scope for this thesis.

Des méthodes efficaces s'appuyant sur des outils statistiques pour réaliser dela reconnaissance de mouvement ont été développé. Ces méthodes reposent surl'apprentissage de primitives situé dans des espaces approprié, par exemplel'espace latent de l'espace articulaire et/ou d'espace de tâches adéquat. Lesprimitives apprises sont souvent séquentielle: un mouvement est segmenté selonl'axe des temps. Dans le cas d'un robot humanoïde, le mouvement peut êtredécomposé en plusieurs sous-tâches simultanées. Par exemple dans un scénario deserveur, le robot doit placer une assiette sur la table avec une main tout enmaintenant son plateau horizontal avec son autre main. La reconnaissance nepeut donc pas se limiter à une seule et unique tâche par segment de tempsconsécutif. La méthode présenté dans ces travaux utilise la connaissance destâches que le robot est capable d'accomplir, ainsi que des contrôleurs quigénèreront les mouvements pour réaliser une rétro ingénierie sur un mouvementobservé. Cette analyse est destinée à reconnaître des tâches qui ont été exécutéde manière simultanées. La méthode repose sur la fonction de tâche et lesprojections dans l'espace nul des tâches afin de découpler les contrôleurs.L'approche a été appliqué avec succès sur un vrai robot pour distinguer desmouvements visuellement très proches, mais sémantiquement différents / Efficient methods to perform motion recognition have been developed usingstatistical tools. Those methods rely on primitives learning in a suitablespace, for example the latent space of the joint angle and/or adequate taskspaces. The learned primitives are often sequential : a motion is segmentedaccording to the time axis. When working with a humanoid robot, a motion can bedecomposed into simultaneous sub-tasks. For example in a waiter scenario, therobot has to keep some plates horizontal with one of his arms, while placing aplate on the table with its free hand. Recognition can thus not be limited toone task per consecutive segment of time. The method presented in this worktakes advantage of the knowledge of what tasks the robot is able to do and howthe motion is generated from this set of known controllers to perform a reverseengineering of an observed motion. This analysis is intended to recognizesimultaneous tasks that have been used to generate a motion. The method relieson the task-function formalism and the projection operation into the null spaceof a task to decouple the controllers. The approach is successfully applied ona real robot to disambiguate motion in different scenarios where two motionslook similar but have different purposes