Dissertations / Theses on the topic 'Enhancing'

Grammatical Evolution (GE) is a method of utilising a general purpose evolutionary algorithm to ???evolve??? programs written in an arbitrary BNF grammar. This thesis extends GE as follows: GE as an extension of Genetic Programming (GP) A novel method of automatically extracting information from the grammar is introduced. This additional information allows the use of GP style crossover which in turn allows GE to perform identically to a strongly typed GP system as well as a non-typed (or canonical) GP system. Two test problems are presented one which is more easily solved by the GP style crossover and one which favours the tradition GE ???Ripple Crossover???. With this new crossover operator GE can now emulate GP (as well as retaining its own unique features) and can therefore now be seen as an extension of GP. Dynamically Defined Functions An extension to the BNF grammar is presented which allows the use of dynamically defined functions (DDFs). DDFs provide an alternative to the traditional approach of Automatically Defined Functions (ADFs) but have the advantage that the number of functions and their parameters do not need to be specified by the user in advance. In addition DDFs allow the architecture of individuals to change dynamically throughout the course of the run without requiring the introduction of any new form of operator. Experimental results are presented confirming the effectiveness of DDFs. Self-Selecting (or variable) crossover. A self-selecting operator is introduced which allows the system to determine, during the course of the run, which crossover operator to apply; this is tested over several problem domains and (especially where small populations are used) is shown to be effective in aiding the system to overcome local optima. Spatial Co-Evolution in Age Layered Planes (SCALP) A method of combining Hornby???s ALPS metaheuristic and a spatial co-evolution system used by Mitchell is presented; the new SCALP system is tested over three problem domains of increasing difficulty and performs extremely well in each of them.

Web browsing has become an integral part of our lives, and we use browsers to perform many important activities almost everyday and everywhere. However, due to the vulnerabilities in Web browsers and Web applications and also due to Web users' lack of security knowledge, browser-based attacks are rampant over the Internet and have caused substantial damage to both Web users and service providers. Enhancing Web browsing security is therefore of great need and importance.;This dissertation concentrates on enhancing the Web browsing security through exploring and experimenting with new approaches and software systems. Specifically, we have systematically studied four challenging Web browsing security problems: HTTP cookie management, phishing, insecure JavaScript practices, and browsing on untrusted public computers. We have proposed new approaches to address these problems, and built unique systems to validate our approaches.;To manage HTTP cookies, we have proposed an approach to automatically validate the usefulness of HTTP cookies at the client-side on behalf of users. By automatically removing useless cookies, our approach helps a user to strike an appropriate balance between maximizing usability and minimizing security risks. to protect against phishing attacks, we have proposed an approach to transparently feed a relatively large number of bogus credentials into a suspected phishing site. Using those bogus credentials, our approach conceals victims' real credentials and enables a legitimate website to identify stolen credentials in a timely manner. to identify insecure JavaScript practices, we have proposed an execution-based measurement approach and performed a large-scale measurement study. Our work sheds light on the insecure JavaScript practices and especially reveals the severity and nature of insecure JavaScript inclusion and dynamic generation practices on the Web. to achieve secure and convenient Web browsing on untrusted public computers, we have proposed a simple approach that enables an extended browser on a mobile device and a regular browser on a public computer to collaboratively support a Web session. A user can securely perform sensitive interactions on the mobile device and conveniently perform other browsing interactions on the public computer.

ASSISTments is an online adaptive tutoring system with the ability to provide assistance to students in the form of hints and scaffolding. ASSISTments has many features to help students improve their knowledge. Researchers run studies in order to discover ways for students to learn better but ASSISTments is missing one major aspect for researchers: student level personalization. It is easy to create an assignment for a particular class or school but it would take much longer to create an assignment for each student and it would be difficult for the teacher to look through many assignment reports. One of the strongest code blocks in coding is the if-then; allowing the program to branch off to another set of code under certain circumstances. ASSISTments needed an if-then system in order for students to branch off to other parts of the assignment under certain circumstances. With this, researchers would be able to personalize assignments to give more help to lower knowledge students or allow students to get a choice of what kind of tutoring they would like to receive. With this idea in mind, the basic if-then structure was implemented into ASSISTments using problem or problem set correctness as the condition statement. Once the if-then system was created opportunities opened to create additional experiments and run studies in ASSISTments. The basic if-then was limited in using correctness only for its condition statement. This meant that a new if-then system would need to be implemented to include custom condition statements that allowed the researcher to have the assignment branch on any condition using all the information recorded in the assignment. While work was being done on the if-then system, research was being done and two papers were written on partial credit in ASSISTments. Partial credit was found out to be as accurate as knowledge tracing in determining student performance on the next problem. Once a partial credit algorithm was found, a study using if-then was analyzed. It was found that there was no statistically significant difference between students who were given a choice on their feedback and students who received no choice.

A review of navigation systems nowadays shows that new features are required in the automotive field. One such feature is suggesting a parking space within a positioning system. In the new global context of navigation, finding a parkingplace has become a central issue for all drivers. The research question for this study is what happens when you get to the destination or when you don’t need to use a GPS to arrive to your destination? This thesis has two major purposes:(1) to investigate an efficient solution for detecting the parking behavior of a moving car; (2) to implement and integrate an environment-friendly solution for HERE in a way that would give the company a competitive edge. By examining only the latitude and longitude from all the input GPS data received in a navigation system, the author defines the best configuration for a parking detection algorithm. Once the best configuration was found, an implementation was proposed. An extensive series of tests has been carried out on the final implementation. Data for tests was obtained using internal tools from HERE for producing different testing routes as navigation files (.nmea files). Creating the input files manually offers flexibility and gives the opportunity to touch all the unexpected behaviors, knowing the expected result in any case. The results obtained from the analysis of the algorithm are encouraging.It has been shown that the configuration chosen for implementation is cheap and effective in predicting parking behavior. In conclusion, the implementation of the algorithm was successfully integrated with the existing HERE SDK. The new feature will be available for the following three automotive companies: Audi, BMW, and Daimler. The algorithm is designed such that it can be easily extended and improved. Future work might include adding parameters that should be adjustable by the user or client like speed of the car.
En genomgång av nutida navigationssystem visar att nya funktioner krävs för fordonsområdet. En sådan funktion är att föreslå en parkeringsplats inom ett positioneringssystem. I det nya globala sammanhanget för navigering har problemet att hitta en pa parkeringsplats blivit en central fråga för alla förare. Frågeställningen för denna studie är vad som händer när du kommer till destinationen eller när du inte behöver använda en GPS för att komma fram till din destination? Denna avhandling har två huvudsakliga syften: (1) att undersöka en effektiv lösning för detektering av parkeringsbeteende hos en bil som rör sig; (2) att genomföra och integrera en miljövänlig lösning för HERE på ett sätt som skulle ge bolaget en konkurrensfördel. Genom att endast undersöka latitud och longitud från all GPS-indata som mottags i ett navigationssystem definierar författaren den bästa konfigurationen för en parkeringdetekteringsalgoritm. När väl den bästa konfigurationen funnits föreslots ett genomförande. En omfattande serie tester har utförts på det slutliga genomförandet. Data för prov erhölls med hjälp av interna verktygfrån HERE för att producera olika provvägar som navigationsfiler (.nmea filer). Att skapa indatafiler manuellt erbjuder flexibilitet och ger möjlighet att vidröra alla oväntade beteenden, för att veta det förväntade resultatet i vilket fall som helst. De resultat som erhållits från analysen av algoritmen är uppmuntrande. Det har visats att konfigurationen som valts för genomförandet är billig och effektiv i att förutsäga parkeringsbeteende. Sammanfattningsvis har genomförandet av algoritmen framgångsrikt integrerats med den befintliga HERE SDK:n. Den nya funktionen kommer att finnas tillgänglig för följande tre bilföretag: Audi,BMW och Daimler. Algoritmen är utformad så att den lätt kan utvidgas och förbättras. Framtida arbete kan omfatta att lägga till parametrar som bör vara inställningsbara av användaren eller kunden som till exmpel hastigheten på bilen.

Recursion is one of the most important and hardest topics in lower division computer science courses. As it is an advanced programming skill, the best way to learn it is through targeted practice exercises. But the best practice problems are hard to grade. As a consequence, students experience only a small number of problems. The dearth of feedback to students regarding whether they understand the material compounds the difficulty of teaching and learning CS2 topics. We present a new way for teaching such programming skills. Students view examples and visualizations, then practice a wide variety of automatically assessed, small-scale programming exercises that address the sub-skills required to learn recursion. The basic recursion tutorial (RecurTutor) teaches material typically encountered in CS2 courses. The advanced recursion in binary trees tutorial (BTRecurTutor) covers advanced recursion techniques most often encountered post CS2. It provides detailed feedback on the students' programming exercise answers by performing semantic code analysis on the student's code. Experiments showed that RecurTutor supports recursion learning for CS2 level students. Students who used RecurTutor had statistically significant better grades on recursion exam questions than did students who used a typical instruction. Students who experienced RecurTutor spent statistically significant more time on solving programming exercises than students who experienced typical instruction, and came out with a statistically significant higher confidence level. As a part of our effort in enhancing recursion learning, we have analyzed about 8000 CS2 exam responses on basic recursion questions. From those we discovered a collection of frequently repeated misconceptions, which allowed us to create a draft concept inventory that can be used to measure student's learning of basic recursion skills. We analyzed about 600 binary tree recursion programming exercises from CS3 exam responses. From these we found frequently recurring misconceptions. The main goal of this work is to enhance the learning of recursion. On one side, the recursion tutorials aim to enhance student learning of this topic through addressing the main misconceptions and allow students to do enough practice. On the other side, the recursion concept inventory assesses independently student learning of recursion regardless of the instructional methods.
Ph. D.

Quick Response code opens possibility to convey data in a unique way yet insufficient prevention and protection might lead into QR code being exploited on behalf of attackers. This thesis starts by presenting a general introduction of background and stating two problems regarding QR code security, which followed by a comprehensive research on both QR code itself and related issues. From the research a solution taking advantages of cloud and cryptography together with an implementation come after. We also give an objective evaluation on the outcome in comparison to existing QR products. They are based on the purpose of enhancing QR code security and aim to interpret how we have tackle the specified problems meanwhile to suggest possible further work for bringing security of QR code to a higher level.

In this thesis we present a new way of extracting relevant data from texts. We use the method presented in the paper by Patwardhan and Rilo (2007), with improvements of our own. Our approach modifes the input to the support vector machine, to construct a self-trained relevant sentence classi er. This classffer is used to identify relevant sentences on the MUC-4 terrorism corpus.We modify the input by removing stopwords, converting words to its stem and only using words that occur at least three times in the corpus. We also changed how each word is weighted, using TF x IDF as weighting function. By using the relevant sentence classiffer together with domain relevant extraction patterns, we achieved higher performance on the MUC-4 terrorism corpus than the original model.

The subject of this dissertation is the construction of privacy-enhancing technologies (PETs) for transparency logging, a technology at the intersection of privacy, transparency, and accountability. Transparency logging facilitates the transportation of data from service providers to users of services and is therefore a key enabler for ex-post transparency-enhancing tools (TETs). Ex-post transparency provides information to users about how their personal data have been processed by service providers, and is a prerequisite for accountability: you cannot hold a controller accountable for what is unknown. We present three generations of PETs for transparency logging to which we contributed. We start with early work that defined the setting as a foundation and build upon it to increase both the privacy protections and the utility of the data sent through transparency logging. Our contributions include the first provably secure privacy-preserving transparency logging scheme and a forward-secure append-only persistent authenticated data structure tailored to the transparency logging setting. Applications of our work range from notifications and deriving data disclosures for the Data Track tool (an ex-post TET) to secure evidence storage.
The subject of this dissertation is the construction of privacy-enhancing technologies (PETs) for transparency logging, a technology at the intersection of privacy, transparency, and accountability. Transparency logging facilitates the transportation of data from service providers to users of services and is therefore a key enabler for ex-post transparency-enhancing tools (TETs). Ex-post transparency provides information to users about how their personal data have been processed by service providers, and is a prerequisite for accountability: you cannot hold a controller accountable for what is unknown. We present three generations of PETs for transparency logging to which we contributed. We start with early work that defined the setting as a foundation and build upon it to increase both the privacy protections and the utility of the data sent through transparency logging. Our contributions include the first provably secure privacy-preserving transparency logging scheme and a forward-secure append-only persistent authenticated data structure tailored to the transparency logging setting. Applications of our work range from notifications and deriving data disclosures for the Data Track tool (an ex-post TET) to secure evidence storage.

The rapid growth of population and the increasing number of vehicles haveled to high accident rates and cause frequently traffic congestion, especiallyin densely populated countries. There is an urgent need to develop and deployIntelligent Transport Systems (ITSs), in order to improve traffic efficiencyand reduce traffic accidents. The emergence and development of advancedtechnologies lays a good foundation for ITSs; for example, wireless communicationand sensing technologies. To promote the popularity of ITSs, we proposesmartphone-based ITSs, in which a smartphone is a part of the ITSs and actsas an interactive interface for users. We choose the widely used and openAndroid operating system as our platform and we demonstrate how to developvehicular applications in Android by making use of Android Interface DefinitionLanguage (AIDL). Security is a critical requirement in development of allkinds of distributed systems, and it should be taken into consideration in thedevelopment of ITSs as well. We studied several security schemes designed forITSs and improved them to better fit the limited computation capabilities andpower of smartphones. The security modules and the client applications areseparated, which makes the applications easier to maintain and use. The projectcarried out evaluation for the implemented security schemes. Our evaluationresults show the practicality of our implementation, which means the securityschemes fit the limited resource of smartphone.

The thesis is focused on the development and enhancement of the electrochemical properties of the carbon based supercapacitors and pseudocapacitors. To overcome the capacitance loss at the condition of fast charging in the carbon-based supercapacitors, a metal-oxide embedded porous carbon nanofiber with a 3-D electrode architecture is designed. This electrode reduces the electrode resistance and at the same time increases the associated values of capacitance at high rates. The investigation also indicates an essential role in the concentration of the metal oxide precursor towards the electrochemical behavior of the electrodes. This correlation could be useful to design better electrodes for supercapacitor, functioning with better energy and power density capabilities. Whereas, in the case of the water-based pseudocapacitors, it is shown that they suffer from low voltages. Two strategies were used to overcome this issue. (i) Exploring and improving the electrode material based non-carbon materials. In this regard, new materials from the family of MXenes are introduced, to achieve higher cell voltages. Under this frame, a new 2-D MXene based on Molybdenum Vanadium Carbide is proposed and its electrochemical characteristics were investigated. According to its characteristics, its coupling with 2-D Titanium Carbide MXene exhibits a higher cell voltage. The investigation reveals that the charge storage in 2-D molybdenum vanadium carbide MXene has the dependence on the type of electrolyte cations. For the case in point, small size monovalent cations, such as lithium and sodium ions, demonstrate lower hindrance to the charge storage, while large size monovalent potassium ions and bivalent magnesium ions suffer from hindrance effect, causing them to have lower charge storage than lithium and sodium ions. Therefore, the selection of appropriate electrolyte ions especially in the case of MXene based materials appears to be important, which is here found to be with the protonic and sodium ion based electrolytes. (ii) the proposed approach is based on the use of water-based super-concentrated salt solutions which are promising electrolytes to contribute to widening the cell voltage of aqueous pseudocapacitors. Likewise, besides this, it is also proposed that the coupling of 2-D Titanium Carbide MXene with the tunnel structures of Manganese Oxide using this super-concentrated electrolyte water in salt can enable a high voltage aqueous pseudocapacitive energy storage device. The investigation using this approach reveals that the concentration of the salt electrolyte plays a significant role in the values of charge storage in 2-D titanium carbides. Although an extremely high concentration of salt electrolytes widens the potential window, the electrolyte ions in such high concentration face difficulty to insert within the 2-D layers of titanium carbide MXene. On the contrary, the use of low concentrated salt solutions is not recommended, as they provide narrow potential windows. Consequently, during the cell assembling using super-concentrated electrolytes, a moderate concentration of salt electrolyte needs to be taken into attention. On this way, both wider potential window and high charge storage, can be achieved with pseudocapacitive materials like 2-D titanium carbides MXenes. The crystallographic tunnel size of manganese oxide plays a vital role in the charge storage. For instance, tunnel structures, both smaller and larger than the size of the electrolyte ions store fewer charges. As both of these tunnel phases of manganese oxide face difficulty for the insertion of the electrolyte ions. Therefore, manganese oxide with adequate tunnel size needs to be taken into account. Besides this, it is also essential to consider the electronic conductivity of the manganese oxide phase, as high electronic conductivity allows it to store more charges during the condition of fast charging. In regards of the cell assembly, after considering the above-mentioned understanding the practice of applying the voltage-hold test to determine the realistic cell voltage is helpful, as the cell assembled with such realistic voltages permits the cell to have long cycle life. Besides these understanding, remarkable performances were witnesses with the technologies developed in this thesis. For example: (i) the carbon-based electric double layer supercapacitor shows faster responses than the existing carbon-based supercapacitors, (ii) the pseudocapacitors shows high volumetric capacitances (> 35 F cm-3) than carbon-based supercapacitors. Besides this, pseudocapacitors also exhibit higher cells voltages than the existing pseudocapacitors. The pseudocapacitor cells developed in this exhibits high electrochemical stability (> 95 %) over thousands of cycles. Furthermore, the pseudocapacitor is more favorable than EDLCs in applications as they provide slower self-discharges than EDLCs. The above understanding, such as the selection of the electrode, electrode processing and the cell assembly is a tool for designing better supercapacitors.
La tesis se centra en el desarrollo del conocimiento orientado y conducido a la mejora de las propiedades electroquímicas de los supercapacitores, ya que sufren bajos valores de densidad de energía. Este inconveniente limita a los supercapacitores en las aplicaciones donde son necesarios tanto alta potencia como densidad de energía. Entonces, en este escenario, se identificaron dos problemas principales importantes: (a) las limitaciones de rendimiento del supercapacitor debido a la condición de carga rápida, y (b) el bajo voltaje de celda de los pseudocapacitores en electrolitos acuosos en comparación con los electrolitos orgánicos. Para superar la limitación de rendimiento en el primer problema, se muestra una alternativa original a través del electrospinning para diseñar nanofibras de carbono porosas con incrustaciones de óxido metálico con una arquitectura de electrodo 3D que contribuyen a reducir la resistencia del electrodo y al mismo tiempo aumentan los valores asociados de capacidad. La investigación indica un papel esencial en la concentración del precursor de óxido metálico hacia el comportamiento electroquímico de los electrodos. Esta correlación podría ser útil para diseñar mejores electrodos para supercapacitadores, funcionando con mejores capacidades de densidad de energía y potencia. En lo que respecta al problema relacionado con los bajos voltajes celulares en el pseudocapacitor acuoso, en lugar de utilizar materiales basados en carbono más estándar, se toma una metodología en términos de exploración y mejora basada en las propiedades del material del electrodo. Así, se introducen nuevos materiales de la familia de MXenes, para lograr voltajes de celda más altos. Bajo este marco, se propone un nuevo MXene 2-D basado en carburo de vanadio y molibdeno y se han investigado sus características electroquímicas. De acuerdo con sus características, su acoplamiento con carburo de titanio 2-D MXene exhibe un voltaje más alto en una celda pseudocapacitiva todo en MXene. Además de esto, el problema del bajo voltaje de la celda también se resuelve aplicando otro enfoque basado en la modificación del electrólito. El enfoque propuesto se basa en el uso de soluciones salinas superconcentradas a base de agua que son electrolitos prometedores en la ampliación del voltaje celular de los pseudocapacitores acuosos. Del mismo modo, también se propone que el acoplamiento del carburo de titanio 2-D MXene con las estructuras del túnel de óxido de manganeso utilizando este electrolito súper concentrado o agua en sal permite lograr una celda de pseudocapacitador acuoso de alto voltaje. En conjunto, la estrategia presentada a través de esta tesis en términos de preparación de electrodos, selección de materiales, ensamblaje celular y su evaluación de las propiedades electroquímicas es una herramienta para diseñar supercapacitores con mejores capacidades de energía y potencia.

The Australian Government expects universities to engage in technology transfer and commercialisation (TT&C) and almost all universities have established a technology transfer office (TTO) for this purpose. The primary aim of this research was to identify what would enhance the overall performance of Australian universities in research commercialisation and industry uptake of the university research commercialisation outcomes. Four research questions were enunciated: 1 What are the systemic barriers to research commercialisation within Australian universities? 2 How could Australian universities overcome the systemic barriers to the commercialisation of university research? 3 How, in particular, could Australian smaller and regional universities enhance their research commercialisation capacity and performance? 4 How could the uptake by industry of Australian university research outcomes be improved? Question 1 was answered using a qualitative content analysis on the substantial body of literature available. Questions 2 and 3 were answered using multiple-case analysis involving eight Australian university case studies and comparing Australian university practice with five benchmark universities œ two from the US, two from Canada, and one from New Zealand. The first major conclusion was that there are three essential criteria upon which university TT&C success is built: institutional and senior executive support for TT&C superior TTO management; and sufficient world-class research being conducted. The second major conclusion was that the same key criteria for success in TT&C apply across the board, whether a university is smaller, regional, technical, new or old, research-intensive or otherwise. Question 4 was answered using case studies developed on five SME companies in the electronics industry in one Australian State and comparing these results with the outcome of a narrative review conducted on the literature to permit methodological triangulation. The research found a rich engagement occurring between universities and industry, with the most important element involving individual personal relationships.

Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains xi, 87 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Renewable energy combined with energy efficiency can offer a viable and influential solution to minimise the harmful consequences of both fossil fuel depletion and increases in the cost of power generation. However, in most cases renewable energy technologies require high initial investments that may deter potential users. Pavement Energy Systems (PES) potentially offer a low-cost solution to sustainable and clean energy generation by utilising the thermo-physical properties and design features of new/existing pavement infrastructure. Within the PES, fluid-filled pipes are buried in the pavement at varying depths and transfer heat to and from the surrounding material, for application as a solar energy collector and/or thermal storage media. The fluid in the pipes can absorb/reject heat to the pavement and deliver useful energy to nearby buildings as well as benefiting the pavement structure and pavement users (in terms of reduced rutting, winter road maintenance, etc.). A significant advantage of such systems is that the pipes can be installed within pavements that are already needed for structural reasons and need not to be installed as single-function elements, as do conventional thermal utilisation systems. In this project, the effect of pavement materials and layer design optimisations on the performance of PES was investigated both theoretically and experimentally. The thermo-physical properties and load-bearing performance of concrete and asphalt pavements, consisting of conventional and unconventional components, were determined. In addition, pseudo 3D transient explicit finite-difference software was developed for modelling and performance analysis of the PES under various operating conditions and configurations. This software is capable of predicting the outlet fluid temperature and temperature distributions within the pavement structure. Furthermore, large-scale physical models of the PES were designed and constructed to compare the performance of the thermally modified pavement structures with those of conventional ones and also to validate the model. The physical model consisted of copper pipes embedded in pavements which were irradiated (causing surface heating) using halogen lamps. The results of thermo-physical optimisation of pavement materials, coupled with mechanical testing, showed that it was possible to achieve a wide range of thermally-modified pavements that can also meet the rigorous functional requirements of an airfield pavement. The experimental comparison between the thermally modified and unmodified concrete pavements revealed that there was potential to enhance both the heat collection and storage capability of concrete pavement structures. In addition, the model’s predicted temperatures in concrete pavements were in good agreement with the experimental ones with a mean error of less than 1°C. A similar comparison on asphalt pavements showed that although the surface temperature was lowered by asphalt modification, there were significant discrepancies between the measured and predicted surface temperatures for both modified and unmodified pavements. Further study was conducted on the pipe/pavement interface using X-Ray Computed Tomography (XRCT). The X-ray images revealed improper bonding between the pavement’s matrix and the pipe that was evidenced by the presence of air voids accumulation around the pipe perimeter, and could explain the significant discrepancy in the modelled temperatures. Furthermore, the validated model was used, for genuine temperature patterns, to simulate the relative influence of both the thermo-physical properties of pavement materials and the pavement layer sequences on the performance of the PES and to determine the implications for pavement design. It was concluded that the enhancements could allow pipes tobe installed deeper within the pavement without having any negative effect on their thermal performances. Pipe installation deeper in the pavement is expected to reduce ‘reflective cracking' under traffic loading as well as enabling future resurfacing of the pavement without damaging the pipe network.

Fouling of filter media and physico-chemical properties of suspensions decrease the efficiency of filtration devices in a wide range of process industries. Environmental protection causes increasing demand to clean effluent waters to higher standards and to recycle process waters more completely. Conventional deliquoring processes are mainly based on a single driving force, usually gravity, underpressure or pressure. Today, multiforce deliquoring processes based on a combination of ultrasonic and/or other nonmechanical forces, like an electric field, are being developed. These new technological applications, namely electro-acoustic deliquoring techniques, will most probably enable higher deliquoring rates and final solid contents than conventional methods have been able to yield. Results from an experimental study of electric and/or ultrasonic field assisted filtrations are presented in this thesis. Both electric and ultrasonic fields can reduce fouling of the filtration medium and have a significant influence on filtration capacity. The extent of filtration improvement is affected mostly by particle size, surface charge, acoustic frequency, intensity and field strengths. Theoretical examinations of the use of electric and/or ultrasonic fields to enhance filtration efficiency are laid out. Some aspects regarding orthokinetic interaction in acoustic agglomeration have been considered, and energy consumptions of the filtrations of different suspensions used in experiments were also determined. Using electric field as a pre-treatment, biolfiber suspension filtration can be enhanced 4-fold and energy consumption of electric field enhancing the filtration (kWh kg1 separated water; product final dry solid content 23 % by mass) was only about 17 % of the total energy consumption of conventional vacuum filtration. Pre-treatment units can be connected to the filtration unit, for instance before the filter drum. Possible pre-treatment apparatuses could be electroflotation equipment or a pre-treatment tube technique introduced in this Ph.D. Thesis…

GT-ITMis a topology generation tool. Since its release GTITMis widely used in the scientific community for network simulations. GTITM is extended to support routing on its topology. The routing algorithm used for interdomain routing attempts to emulate the BGP routing protocol seen on the internet. It uses a policy file if supplied to make routing decisions. An additional functionality provided with the tool is the ability to automatically generate policy file for large graphs.

The effect of xylan from different plant species on tensile properties of spruce pulp was studied. Xylans from spruce, birch, wheat straw and rice husks were mixed with the fresh white liquor and added at the later stages of separate kraft cooks, in exchange of the black liquor removed from the system at that time. Results show that xylans, from rice husk, wheat straw and birch, gave stronger pulps. However it was only possible to attach small quantities of xylans onto the fibers. Moreover, pulps containing birch and rice xylan were easier to beat than the other pulps in the study.

The first part of this study is devoted to assessing the suitability of soft proofs as a surrogate for the final print in judging colour-reproduction quality. Two sets of psychophysical experiments were carried out. The first investigated whether the type of medium used to generate a stimulus influenced its appearance, while the second attempted to determine whether judgments made on the basis of hardcopy simulation are transferable to prints. The second part of this study is devoted to improve the accuracy of soft proofing by increasing the amount of information rendered on screen. We present a workflow that extends traditional colorimetry beyond simple colour appearance prediction to a higher dimensional representation, which includes gloss. The intention is to provide a full goniometric simulation of the spatial distribution of light reflected by a print based upon data gathered with simple and inexpensive instruments, glossmeters and spectrophotometers.

Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2009.
Committee Chair: Ling Liu; Committee Member: Brian Cooper; Committee Member: Calton Pu; Committee Member: Douglas Blough; Committee Member: Karsten Schwan. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This thesis explores underwater imaging solutions in order to alleviate the poor contrast and the distortion in the perception of colour caused by the processes of scattering and absorption. We demonstrate through simulated experiments that imaging systems with higher spectral resolution than RGB could be useful for underwater imaging tasks such as estimating illumination and spectral reflectance values. We also tested hyperspectral imagers in real world experiments and found that the current technology is limited for underwater image enhancement applications. To address the problem of poor visibility in underwater scenes we introduce dehazing methods for underwater RGB images and videos. Current underwater dehazing methods suffer from limitations such as estimated parameters being biased towards pixels of bright objects in a scene and artefacts being created in regions that contain pure haze. Bright objects in a scene are avoided by using texture features during the estimation of parameters and local bias is avoided by taking information from an image at different spatial resolutions. We inhibit noise and artefacts being created in the pure haze regions by segmenting these areas and treating them as a special case. We address the spectral distortion present in underwater scenes by applying a water-type dependent white balancing step. We also demonstrate the application of our method to underwater videos with a weighted temporal smoothing of the estimated parameters and a Gaussian normalisation step that ensures segmentation of pure haze regions is stable across frames. We evaluate our methods both on quantitative metrics and through subjective experiments and demonstrate an improved performance in comparison to the state of the art in underwater image and video enhancement. We also show how no-reference underwater image quality assessment metrics do not always correspond with human judgement and provide suggestions on how they could be improved.

The first part of this thesis is concerned with the synthesis, characterisation and applications of surface functionalised carbon nanoparticles. Synthetic techniques are used to modify the existing surface architecture of carbon nanoparticles towards high surface area modified electrodes and pH sensing applications. Electrochemical and synthetic techniques have been used to study triple phase boundaries and enhance their properties towards a bulk synthetic technique, in which an electrolyte phase and redox probe phase are held separate. A salt matrix, ultrasound, high shear force and a carbon fibre membrane have all been used to form unique triple phase boundary environments in which electron and ion transfer processes can be studied and enhanced towards analytical and electrosynthetic applications. A number of electro-reduction reactions have been shown to be feasible using the triple phase boundary methodology. Alkenes, aldehydes and imines have all been successfully electro-reduced, analysed and optimised to elucidate the synthetic triple phase boundary mechanism.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 77-80).
Shielding critical links enhances network robustness and provides a new way of designing robust networks. We first consider shielding critical links to guarantee network connectivity after any failure under geographical and general failure models. We develop a mixed integer linear program (MILP) to obtain the minimum cost shielding to guarantee the connectivity of a single source-destination (SD) pair under a general failure model, and exploit geographical properties to decompose the shielding problem under a geographical failure model. We extend our MILP formulation to guarantee the connectivity of the entire network, and use Benders decomposition to significantly reduce the running time by exploiting its partial separable structure. We extend the algorithms to guarantee partial network connectivity, and observe that significantly less shielding is required, especially when the failure region is small. To mitigate the effect of random link failures on network connectivity, we consider increasing the effective min-cut of the network by shielding, where shielded links cannot be contained in effective cuts. For a single SD pair, we develop an efficient algorithm to increase the effective min-cut by one, and develop a MILP with a small number of constraints to increase the effective min-cut by an arbitrary value. Then we extend the MILP to obtain the optimal shielding to increase the effective min-cut for the entire network, which can be used to solve realistic size problems. Finally, we consider shielding critical nodes in random graphs. We demonstrate the importance of high degree nodes in random graphs constructed under the configuration model. The occupancy of higher degree nodes leads to a larger size of the giant component. Moreover, shielding a small fraction of nodes in power law random graphs guarantees the existence of a giant component if the exponent is less than three.
by Jianan Zhang.
S.M.

With the inherent functional flexibility of the computer it seemed inevitable that these machines would be put to use in assisting individuals with less functional ability such as the severely physically disabled. These functions would include Speaking, Writing, Controlling their surroundings and moving within those environments. The software applications which provide these functions have collectively become known as Integrated Electronic Assistive Technology (IEAT). This research investigation focused on the prescription of an IEAT prescribed for a particular individual using the Barnsley Wheelchair Interface (BWI) to enable the individual's function of mobility. The BWI controlled an electric wheelchair via a single switch pressed by the user, using her head and was prescribed using the "Multi-Disciplinary Service Model" process created and described by Hawley (1995).The subsequent enhancement of this prescription, from the model-based analysis of the automatically generated usage data logs, that were introduced by the PhD Research student and are one of the novel features of this work. The chosen method, using the analysis of data logs came about as a result of the PhD Research student's own severe physical disability rendering conventional techniques difficult and in some cases impossible. It is the model-based analysis processes that have been developed during this research and which inform the Assistive Technology Professional (ATP) with general information on the prescription, along with comprehensive information on 'Whole System Information', 'Functional Level Information' and 'Interface Level Information', which in all instances had previously been unavailable from assistive technology stakeholders. It is speculated that with the use of these analysis processes (tools) in addition to a software application called "Switch Environment Assessment Tool" (SEAT), in conjunction with the iterative process within the service model, the prescription should be enhanced, resulting in an increase in the user's quality of life.

The significant decline in flower-visiting invertebrate populations across Europe has been largely attributed to habitat loss and agricultural intensification. To facilitate and enhance population growth, reversal of biodiversity loss within the local landscapes should be addressed. This study identifies and assesses habitat features associated with flower-visiting invertebrates with the aim to develop management targets to enhance biodiversity. The abundance and diversity of flower-visiting invertebrates were compared between six habitat areas within the grounds of the Alcan Aluminium smelter. The majority of invertebrates were attracted to high flower density, rather than a particular habitat area. Underpinning the project, this study identified three priority habitats utilised by invertebrates; Grassland, Woodland, and Hedgerows. Within grassland, the impact of mowing regimes on flower-visiting invertebrates and flowering plants was assessed. A reduction in mowing frequency resulted in a significant increase of both flower density and diversity within the sward. Comparisons to local flower-rich grasslands showed that following appropriate management the grassland at the Alcan smelter was comparable, if not better in some cases in terms of flower density, along with increasing stability of the plant and invertebrate network. Steps to establish a diverse understorey within the woodland began with an assessment of the seedbank. Results closely mimicked the above ground flora, confirming a low abundance and diversity of flowering species. Germination trials followed to determine the suitability of current light levels to support woodland flowering plants; findings indicated the need for canopy management to enhance the woodland. Hedgerows are an important landscape feature for invertebrates, this study showed that species-rich hedgerows hosted a greater diversity of invertebrates than species poor hedgerows. Indicating the importance of hedgerow management, and the potential benefits of gap filling with native shrub species. Finally, the presence of suitable nesting habitat is another important consideration when managing habitats for invertebrates. Here we assessed the use of three different substrates for suitability in building artificial nests (aimed primarily at bees and wasps). The uptake of these nests increased with exposure length, suggesting that artificial nests do indeed support breeding invertebrates, and could be successfully used as a tool for invertebrate conservation in the future.

Since the inception of the 802. 11 standard in 1999, WLANs, which used to be exceptional, became a massive phenomenon together with the evolution of portable devices. At the same pace, research on wireless networks, where both simulation and experimentation are used to validate protocols, has evolved rapidly. Nevertheless, the models used in this area were adapted from the wired paradigm, which has led to a significant gap between the simulated and the experimental results. Therefore, to validate wireless protocols or algorithms, wireless experimentation becomes an important resource. This thesis explores the improvements to experimentation on WLANs, from a methodological point of view. In this thesis, we first create a new model for data abstraction to represent network events and aggregated data logs; second, we design a methodology to manage data in order to support a database model; and third we replace custom made processing scripts with data-oriented filter modules. These three key points converge into a wireless experimentation methodology to specify the experimental conditions and improve reproductibility. Furthermore, we present Wextool, an implementation of a Wireless Experimentation Tool which applies the methodology and finally we show the improvements through a wireless multicast experimentation use case and a performance evaluation of the process
Depuis la création de la norme 802. 11 en 1999 qui était exceptionnelle à l’époque, les réseaux locaux sans fil sont devenus un phénomène incontournable avec l’évolution des appareils mobiles. La recherche sur les réseaux sans-fil a rapidement évolué suivant des modèles adaptés du paradigme des réseaux filaires ce qui a conduit à un écart significatif entre la simulation et les résultats expérimentaux. En conséquence, afin de valider les protocoles sans fil ou les algorithmes, l’expérimentation sans fil devient un ressource importante. Cette thèse étudie les améliorations sur l’expérimentation sur les réseaux locaux sans fil, d’un point de vue méthodologique. Dans cette thèse, nous avons d’abord crée un nouveau modèle d’abstraction de données pour représenter les événements de réseau et de l’agrégation de données statistiques, en deuxième lieu, nous élaborons une méthodologie pour la gestion des données en vue de soutenir un modèle de base de données et enfin on remplace le traitement avec scripts sur mesure avec des modules de filtrage et de traitement. Ces trois principaux éléments convergent vers une méthodologie d’expérimentation qui pointe sur les conditions d’expérience et d’amélioration de la reproductibilité. De plus, nous présentons Wextool, outil de méthodologie pour la mise en oeuvre expérimentale sans fil et enfin, nous montrons les améliorations à travers une étude du multicast dans un scénario sans fil comme un cas d’utilisation et nous évaluons la performance du processus

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 79-85).
Security notification schemes hold great promise for improving both consumer cybersecurity and general network health as malware and other sources of malicious activity are becoming more prevalent on home networks. For example, botnets of Internet of Things devices engage in denial of service (DoS) attacks and ransomware holds data on personal and commercial systems hostage. Many of these threats are relatively opaque for an end user. An end user may not know that their smart device is participating in a DoS attack at all, unless they notice a protracted slowdown in network speeds. An upstream network provider like a consumer ISP has more visibility into the issue. Due to their privileged position, ISPs often have more data about the status of a malware infection, denial of service attack, or other malicious activity. This extra information can be of great benefit for the purposes of notification. For instance, an ISP may be able to notify a customer that a device on their network is being used for a DoS attackor that they see communication with a server involved in distributing ransomware. ISPs and other organizations that try and implement these schemes often run into a set of questions: How do I get the right data to power the notification? How do I ensure the user trusts the notification? Can I ensure the notification is not spoofed? Is there an optimal way to present the notification? How do I make sure a user takes the proper remedial action? This thesis presents a framework for new notification schemes to answer these questions by examining four key elements of a notification: form, delivery, and content. It also proposes multi-factor verification, a novel scheme to address trust and spoofing issues within a notification scheme. Finally, it provides a model for a new ISP-user security notification scheme within the context of the United States market and policy landscape.
by Nathaniel H. Fruchter.
S.M. in Technology and Policy
S.M.inTechnologyandPolicy Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program

This thesis presents four different techniques for improving the average-case performance of deterministic sequential circuit Automatic Test Patterns Generators (ATPG). Three techniques make use of information gathered during test generation to help identify more unjustifiable states with higher percentage of â donâ t careâ value. An approach for reducing the search space of the ATPG was introduced. The technique can significantly reduce the size of the search space but cannot ensure the completeness of the search. Results on ISCASâ 85 benchmark circuits show that all of the proposed techniques allow for better fault detection in shorter amounts of time. These techniques, when used together, produced test vectors with high fault coverages. Also investigated in this thesis is the Decision Inversion Problem which threatens the completeness of ATPG tools such as HITEC or ATOMS. We propose a technique which can eliminate this problem by forcing the ATPG to consider search space with certain flip-flops untouched. Results show that our technique eliminated the decision inversion problem, ensuring the soundness of the search algorithm under the 9-valued logic model.
Master of Science

One of the most important objectives for transportation engineers is to understand pavement surface properties and their positive and negative effects on the user. This can improve the design of the infrastructure, adequacy of tools, and consistency of methodologies that are essential for transportation practitioners regarding macrotexture characterization. Important pavement surface characteristics, or tire-pavement interactions, such as friction, tire-pavement noise, splash and spray, and rolling resistance, are significantly influenced by pavement macrotexture. This dissertation compares static and dynamic macrotexture measurements and proposes and enhanced method to quantify the macrotexture. Dynamic measurements performed with vehicle-mounted lasers have the advantage of measuring macrotexture at traffic speed. One drawback of these laser devices is the presence of 'spikes' in the collected data, which impact the texture measurements. The dissertation proposes two robust and innovative methods to overcome this limitation. The first method is a data-driven adaptive method that detects and removes the spikes from high-speed laser texture measurements. The method first calculates the discrete wavelet transform of the texture measurements. It then detects (at all levels) and removes the spikes from the obtained wavelet coefficients (or differences). Finally, it calculates the inverse discrete wavelet transform with the processed wavelet coefficients (without outliers) to obtain the Mean Profile Depth (MPD) from the measurements with the spikes removed. The method was validated by comparing the results with MPD measurements obtained with a Circular Texture Meter (CTMeter) that was chosen as the control device. Although this first method was able to successfully remove the spikes, it has the drawback that it depends on manual modeling of the distribution of the wavelet coefficients to correctly define an appropriate threshold. The next step of this dissertation proposes an enhanced to the spike removal methodology for macrotexture measurements taken with high-speed laser devices. This denoising methodology uses an algorithm that defines the distribution of texture measurements by using the family of Generalized Gaussian Distributions (GGD), along with the False Discovery Rate (FDR) method that controls the proportion of wrongly identified spikes among all identified spikes. The FDR control allows for an adaptive threshold selection that differentiates between valid measurements and spikes. The validation of the method showed that the MPD results obtained with denoised dynamic measurements are comparable to MPD results from the control devices. This second method is included as a crucial step in the last stage of this dissertation as explained following. The last part of the dissertation presents an enhanced macrotexture characterization index based on the Effective Area for Water Evacuation (EAWE), which: (1) Estimates the potential of the pavement to drain water and (2) Correlates better with two pavement surface properties affected by macrotexture (friction and noise) that the current MPD method. The proposed index is defined by a three-step process that: (1) removes the spikes, assuring the reliability of the texture profile data, (2) finds the enveloping profile that is necessary to delimit the area between the tire and the pavement when contact occurs, and (3) computes the EAWE. Comparisons of current (MPD) and proposed (EAWE) macrotexture characterization indices showed that the MPD overestimates the ability of the pavement for draining the surface water under a tire.
Ph. D.

This thesis involves restoration, reconstruction, and enhancement of a digitized library of hand-written documents. Imaging systems that perform this digitization often degrade the quality of the original documents. Many techniques exist for reconstructing, restoring, and enhancing digital images; however, many require a priori knowledge of the imaging system. In this study, only partial a priori knowledge is available, and therefore unknown parameters must be estimated before restoration, reconstruction, or enhancement is possible. The imaging system used to digitize the documents library has degraded the images in several ways. First, it has introduced a ringing that is apparent around each stroke. Second, the system has eliminated strokes of narrow widths. To restore these images, the imaging system is modeled by estimating the point spread function from sample impulse responses, and the image noise is estimated in an attempt to apply standard linear restoration techniques. The applicability of these techniques is investigated in the first part of this thesis. Then nonlinear filters, structural techniques, and enhancement techniques are applied to obtain substantial improvements in image quality.
Master of Science

Currently, there is an increasing need for novel analgesics that are potent but lack undesired side effects. Recent studies have shown that both 5-HT3 receptors and α2B- adrenoceptors play a role in antinociception. MD-354, N-(3-chlorophenyl)guanidine, has a high-affinity both for 5-HT3 and α2B- adrenoceptors and could be viewed as the first example of a rather selective 5-HT3/α2B- adrenoceptor ligand. MD-354, inactive by itself, potentiates the antinociceptive effects of an inactive dose of clonidine in the mouse tail- flick assay. An attempt to determine the underlying mechanism of this potentiating effect was the purpose of the present investigation. The studies focused on an examination of: i) MD-354 in the mouse hot-plate assay, ii) a more lipophilic analog of MD-354 in the tail-flick assay, iii) various analogs of MD-354 with different binding profiles in both mouse tail-flick and hot-plate assays. The present investigation suggests that both 5-HT3 and α2B- adrenoceptors are playing a role in the potentiation of clonidine analgesia by arylguanidines such as MD-354. Arylguanidines might represent a unique class of analgesia-enhancing agents with a dual (5-HT3/α2- adrenoceptor) mechanism of action.

The thesis consists of four articles and this summarizing part. All parts have focused on bringing some insights into how to design a didactical situation including dynamic software (GeoGebra) to support students’ mathematical problem solving and creative reasoning as means for learning. The four included articles are: I. Granberg, C., & Olsson, J. (2015). ICT-supported problem solving and collaborative creative reasoning: Exploring linear functions using dynamic mathematics software. The Journal of Mathematical Behavior, 37, 48-62. II. Olsson, J. (2017). The Contribution of Reasoning to the Utilization of Feedback from Software When Solving Mathematical Problems. International Journal of Science and Mathematics Education, 1-21. III. Olsson, J. Relations between task design and students’ utilization of GeoGebra. Mathematical Thinking and Learning. (Under review) IV. Olsson, J., & Granberg, C. Dynamic software, problem solving with or without guidelines, and learning outcome. Technology, Knowledge and Learning. (Under review) Background A common way of teaching mathematics is to provide students with solution methods, for example strategies and algorithms that, if followed correctly, will solve specific tasks. However, questions have been raised whether these teaching methods will support students to develop general mathematical competencies, such as problem solving skills, ability to reason and acquire mathematical knowledge. To merely follow provided methods students might develop strategies of memorizing procedures usable to solve specific tasks rather than drawing general conclusions. If students instead of being provided with algorithms, are given the responsibility to construct solution methods, they may produce arguments for why the method will solve the task. There is research suggesting that if those arguments are based on mathematics they are more likely to develop problem solving and reasoning-skill, and learn the included mathematics better. In such didactic situations, where students construct solutions, it is important that students have instructions and tasks that frame the activity and clarify goals without revealing solution methods. Furthermore, the environment must be responsive. That is, students need to receive responses on their actions. If students have an idea on how to solve (parts of) the given problem they need to test their method and receive feedback to verify or falsify ideas and/or hypotheses. Such activities could be supported by dynamic software. Dynamic software such as GeoGebra provides features that support students to quickly and easily create mathematical objects that GeoGebra will display as visual representations like algebraic expressions and corresponding graphs. These representations are dynamically linked, if anything is changed in one representation the other representations will be altered accordingly, circumstances that could be used to explore and investigate different aspects and relations of these objects. The first three studies included in the thesis investigate in what way GeoGebra supports creative reasoning and collaboration. These studies focus questions about how students apply feedback from GeoGebra to support their reasoning and how students utilize the potentials of GeoGebra to construct solutions during problem solving. The fourth study examine students’ learning outcome from solving tasks by constructing their methods. Methods A didactical situation was designed to engage students in problem solving and reasoning supported by GeoGebra. That is, the given problems were not accompanied with any guidelines how to solve the task and the students were supposed to construct their own methods supported by GeoGebra. The students were working in pairs and their activities and dialogues were recorded and used as data to analyse their engagement in reasoning and problem solving together with their use of GeoGebra. This design was used in all four studies. A second didactical situation, differing only with respect of providing students with guidelines how to solve the task was designed. These didactical situations were used to compare students’ use of GeoGebra, their engagement in problem solving and reasoning (study III) and students’ learning outcome (study IV) whether the students solved the task with or without guidelines. In the fourth study a quantitative method was applied. The data from study IV consisted of students’ results during training (whether they managed to solve the task or not), their results on the post-test, and their grades. Statistical analysis where applied. Results The results of the first three studies show qualitative aspects of students solving of task with assistance of GeoGebra. GeoGebra was shown to support collaboration, creative mathematical reasoning, and problem solving by providing students with a shared working space and feedback on their actions. Students used GeoGebra to test their ideas by formulating and submitting input according to their questions and hypotheses. GeoGebra’ s output was then used as feedback to answer questions and verify/falsify hypotheses. These interactions with GeoGebra were used to move the constructing of solutions forward. However, the way students engage in problem solving and reasoning, and using GeoGebra to do so, is dependent on whether they were provided with guidelines or not. Study III and IV showed that merely the students who solved unguided tasks utilized the potential of GeoGebra to explore and investigate the given task. Furthermore, the unguided students engaged to a larger extent in problem solving and creative reasoning and they expressed a greater understanding of their solutions. Finally study IV showed that the students who managed to solve the unguided task outperformed, on posttest the students who successfully solved the guided task. Conclusions The aim of this thesis was to bring some insights into how to design a didactical situation, including dynamic software (GeoGebra), to support students' mathematical problem solving and creative reasoning as means for learning. Taking the results of the four studies included in this thesis as a starting point, one conclusion is that a didactical design that engage students to construct solutions by creative reasoning supported by GeoGebra may enhance their learning of mathematics. Furthermore, the mere presence of GeoGebra will not ensure that students will utilize its potential for exploration and analysis of mathematical concepts and relations during problem solving. The design of the given tasks will affect if this will happen or not. The instructions of the task should include clear goals and frames for the activity, but no guidelines for how to construct the solution. It was also found that when students reasoning included predictive argumentation for the outcomes of operations carried out by the software, they could better utilize the potential of GeoGebra than if they just, for example, submitted an algebraic representation of a linear function and then focused on interpreting the graphical output.
Det övergripande syftet med avhandlingen har varit att nå insikter i hur man kan designa en didaktisk situation inklusive en dynamisk programvara (GeoGebra) för att stödja elevernas lärande genom matematisk problemlösning och kreativt resonemang. En bärande idé har varit att elever som själva konstruerar lösningsmetoder till problembaserade uppgifter lär sig matematik bättre än elever som får en metod att följa. Resultaten visar att GeoGebra är ett stöd vid konstruerandet av lösningsmetoder och att elever då också resonerar kreativt. Det vill säga, de skapar en för dem en ny resonemangssekvens som innehåller en lösningsmetod som stöds av argument förankrade i matematik. Idén med att elever på egen hand konstruerar lösningen på uppgifter har även belysts genom att jämföra med elever som löser uppgifter där de får vägledning till lösningsmetoden. Resultaten visar att elever som får en lösningsmetod inte resonerar kreativt, de utnyttjar inte GeoGebras potential att stödja ett undersökande arbetssätt, och de lär sig mindre av den matematik som ingår i uppgifterna. Denna avhandling består av 4 artiklar och en kappa. De fyra artiklarna är: I. Granberg, C., & Olsson, J. (2015). ICT-supported problem solving and collaborative creative reasoning: Exploring linear functions using dynamic mathematics software. The Journal of Mathematical Behavior, 37, 48-62. II. Olsson, J. (2017). The Contribution of Reasoning to the Utilization of Feedback from Software When Solving Mathematical Problems. International Journal of Science and Mathematics Education, 1-21. III. Olsson, J. Relations between task design and students’ utilization of GeoGebra. Mathematical Thinking and Learning. (Under review) IV. Olsson, J., & Granberg, C. Dynamic software, problem solving with or without guidelines, and learning outcome. Technology, Knowledge and Learning. (Under review) Artikel 2 och 3 är jag ensam författare till. Det innebär att jag designat studien, planerat och genomfört datainsamling, analyserat data och formulerat slutsatser, samt skrivit texten och korresponderat med tidskrifter. Artikel 1 och 4 har jag skrivit i samarbete med Carina Granberg. Vi bedömer att arbetet med artikel 1 fördelats lika. Allt skrivarbete har fortgått genom åtskilliga granskningar av varandras utkast och diskussioner om slutgiltiga formuleringar. I arbetet med artikel 4 har jag haft huvudansvaret för designen av studien och planering för datainsamlingen. Skrivarbetet har genomförts på samma sätt som i arbetet med artikel 1.

Transparency is a key principle in democratic societies. For example, the public sector is in part kept honest and fair with the help of transparency through different freedom of information (FOI) legislations. In the last decades, while FOI legislations have been adopted by more and more countries worldwide, we have entered the information age enabled by the rapid development of information technology. This has led to the need for technological solutions that enhance transparency, for example to ensure that FOI legislation can be adhered to in the digital world. These solutions are called transparency-enhancing tools (TETs), and consist of both technological and legal tools. TETs, and transparency in general, can be in conflict with the privacy principle of data minimisation. The goal of transparency is to make information available, while the goal of data minimisation is to minimise the amount of available information. This thesis presents two privacy-preserving TETs: one cryptographic system forenabling transparency logging, and one cryptographic scheme for storing the data for the so called Data Track tool at a cloud provider. The goal of the transparency logging TET is to make data processing by data controllers transparent to the user whose data is being processed. Our work ensures that the process in which the data processing is logged does not leak sensitive information about the user, and thatthe user can anonymously read the information logged on their behalf. The goal of the Data Track is to make it transparent to users which data controllers they have disclosed data to under which conditions. Furthermore, the Data Track intends to empower users to exercise their rights, online and potentially anonymously, with regard to their disclosed data at the recipient data controllers. Our work ensures that the data kept by the Data Track can be stored at acloud storage provider, enabling easy synchronisation across multiple devices, while preserving the privacy of users by making their storage anonymous toward the provider and by enabling users to hold the provider accountable for the data it stores.

This study was aimed to provide insight about affective teaching practices that influence students'
affective characteristics in physics lessons using mixed methodology. Affective characteristics consisted of attitudes and motivation. For this purpose Keller'
s ARCS (attention, relevance, confidence, satisfaction) model was revised by adding Communication category. The Affective Teaching Practices Questionnaire, including these categories, was administered to 1,138 students and 31 physics teachers in Ankara. Moreover, the Affective Characteristics Questionnaire was administered to students to find out the relationship between students'
affective characteristics and their perceptions about the teaching practices used by teachers. Four physics teachers, who were performing teaching practices frequently, were purposefully selected according to results of quantitative phase. In qualitative phase, observations were conducted in these teachers'
classrooms to find out teaching practices used to enhance affective characteristics and their effects. Besides, interviews were conducted to support observations. The quantitative data were analyzed by descriptive statistics, while qualitative data were analyzed by cross case analysis. Results revealed that affective teaching practices are related to students'
affective characteristics. Assisting comprehension and providing role models to students are effective for enhancing affective characteristics. Similarly, providing students concrete materials
arousing their inquiry
organizing what is taught from simple to difficult
attributing success to effort
relating topic to students'
experience
stating clearly what is expected of students
providing feedback
using positive outcomes
giving enough time to students
using clear, understandable, fluent language in lessons
caring about teaching
being self-confident
caring about students
and providing an atmosphere suitable for learning are also effective.

Designing a secured network is the most important task in any enterprise or organization development. Securing a network mainly involves applying policies and procedures to protect different network devices from unauthorized access. Servers such as web servers, file servers, mail servers, etc., are the important devices in a network. Therefore, securing these servers is the first and foremost step followed in every security implementation mechanism. To implement this, it is very important to analyse and study the security mechanisms provided by the operating system. This makes it easier for security implementation in a network. This thesis work demonstrates the tasks needed to enhance the network security in Linux environment. The various security modules existing in Linux makes it different from other operating systems. The security measures which are mainly needed to enhance the system security are documented as a baseline for practical implementation. After analysing the security measures for implementing network security, it is important to understand the role of network monitoring tools and Linux inbuilt log management in maintaining the security of a network. This is accomplished by presenting a detailed discussion on network monitoring tools and log management in Linux. In order to test the network security, a network is designed using Linux systems by configuring different servers and application firewall for packet filtering. The security measures configured on each server to enhance its security are presented as part of the implementation. The results obtained while an unauthorized user accessing the servers from the external network are also documented along with attack information retrieved by different network monitoring tools and Linux inbuilt log messages.

Aluminum powder when ball milled with secondary particles will corrode in water releasing hydrogen. With corrosion rates approaching 90% of available aluminum within 20 minutes, this process is of interest as a portable hydrogen source. Electrochemical polarization and hydrogen capture tests are used to study changes in solution pH and temperature during the reaction as well as calculate the activation energy for corrosion of the ball milled powder. Evidence that the ball milled aluminum is increasing the solution pH is presented along with tests indicating the pH shift is not sufficient to account for the increase in corrosion rate. The effect of solution temperature on reaction products and corrosion rate for aluminum powders is measured, and the hypothesis that the exothermic nature of the reaction combined with a deformed surface is creating high temperature micro-environments is discounted. Activation energy for the rate limiting step in the corrosion of ball milled aluminum is calculated between 72 – 74 kJ/mol, similar to that seen for aluminum disks at a similar pH. Finally BET measurements show an increase in surface area of the aluminum particles after ball milling between 10x-20x. The amount of hydrogen evolved in the first hour is seen to correlate almost exactly with the aluminum surface area. The addition of alumina powder without ball milling is shown to increase the corrosion rate of aluminum powders by an order of magnitude or greater and to delay or prevent passivation of the aluminum. Two models are proposed to explain this observation and tests run to support them. The high surface area (10m²/g) of alumina is thought to provide an alternative deposition site for hydroxide formed during aluminum corrosion and the positive surface charge alumina acquires at pH 7 to provide a source of protons for hydrogen evolution. The hydrogen exchange current densities on aluminum and platinum surfaces are shown to increase by over an order of magnitude in the presence of alumina particles. The acceleration of aluminum corrosion is only seen with electrical contact between the aluminum and alumina, but contact is not required to delay passivation.

Resistance responses of Abutilon theophrasti were investigated to determine defense mechanisms of the weed against Colletotrichum coccodes and to verify if some chemical suppression of the resistance mechanism could be exploited to enhance the virulence. Induced resistance in A. theophrasti has been confirmed in treatments with C. coccodes, benzothiadiazole, bentazon, and acifluorfen. Induction of peroxidase and phenylalanine ammonia lyase (PAL) activities in the leaves that did not contact with the inducing agents was observed after the localized stresses to the first leaf or the root of the plant with those agents. alpha-Amino-oxy acetic acid (AOA), 2-deoxy-D-glucose (DDG), mannose, oxalic acid, and analogues of oxalic acid and mannose were tested to enhance C. coccodes virulence. However, the compounds did not enhance C. coccodes virulence or affect A. theophrasti growth. Strong antifungal effects, poor inhibitory effects on plant defense mechanisms, or minor dependence of A. theophrasti on the defense mechanisms that the chemicals affected could be reasons. The efficacy of C. coccodes increased in the presence of 0.25 kg a.i. ha-1 bentazon more than when C. coccodes was applied alone, while the effect of glyphosate was minimal. Peroxidase activity was strongly induced by the treatment of C. coccodes and increased over time. PAL and activation of peroxidase was inhibited in the presence of bentazon, suggesting the synergy effect by bentazon is probably due to the suppression on the two defense-related enzymes. In conclusion, A. theophrasti exploits various biochemical and morphological types of defense mechanisms against C. coccodes infection. However, the activation of the defense responses can be suppressed or by-passed in an integrated weed management system.