This work extends a previously developed finite-volume overset-grid fluid flow solver to enable the characterisation of rigid-body-fluid interaction problems. To this end, several essential components have been developed and blended together. The inherent time-dependent nature of fluid-solid interaction problems is captured through the laminar transient incompressible Navier-Stokes equations for the fluid, and the Euler-Newton equations for rigid-body motion. First and second order accurate time discretisation schemes have been implemented for the former, whereas second and third order accurate time discretisation schemes have been made available for the latter. Without doubt the main advantage the overset-grid method offers regarding moving entities is the avoidance of the time consuming grid regeneration step, and the resulting grid distortion that can often cause numerical stability problems in the solution of the flow equations. Instead, body movement is achieved by the relative motion of a body fitted grid over a suitable background mesh. In this case, the governing equations of fluid flow are formulated using a Lagrangian, Eulerian, or hybrid flow description via the Arbitrary Lagrangian-Eulerian method. This entails the need to guarantee that mesh motion shall not disturb the flow field. With this in mind, the space conservation law has been hard-coded. The compliance of the space conservation law has the added benefit of preventing spurious mass sources from appearing due to mesh deformation. In this work, two-way fluid-solid interaction problems are solved via a partitioned approach. Coupling is achieved by implementing a Picard iteration algorithm. This allows for flexible degree of coupling specificationby the user. Furthermore, if strong coupling is desired, three variants of interface under-relaxation can be chosen to mitigate stability issues and to accelerate convergence. These include fixed, or two variants of Aitken’s adaptive under-relaxation factors. The software also allows to solve for one-way fluid-solid interaction problems in which the motion of the solid is prescribed. Verification of the core individual components of the software is carried out through the powerful method of manufactured solutions (MMS). This purely mathematically based exercise provides a picture of the order of accuracy of the implementation, and serves as a filter for coding errors which can be virtually impossible to detect by other means. Three instances of one-way fluid-solid interaction cases are compared with simulation results either from the literature, or from the OpenFOAM package. These include: flow within a piston cylinder assembly, flow induced by two oscillating cylinders, and flow induced by two rectangular plates exhibiting general planar motion. Three cases pertaining to the class of two-way fluid-interaction problems are presented. The flow generated by the free fall of a cylinder under the action of gravity is computed with the aid of an intermediate ‘motion tracking’ grid. The solution is compared with the one obtained using a vorticity based particle solver for validation purposes. Transverse vortex induced vibrations (VIV) of a circular cylinder immersed in a fluid, and subject to a stream are compared with experimental data. Finally, the fluttering motion of a rectangular plate under different scenarios is analysed.

abstract: The recent proposal of two-way relaying has attracted much attention due to its promising features for many practical scenarios. Hereby, two users communicate simultaneously in both directions to exchange their messages with the help of a relay node. This doctoral study investigates various aspects of two-way relaying. Specifically, the issue of asynchronism, lack of channel knowledge, transmission of correlated sources and multi-way relaying techniques involving multiple users are explored. With the motivation of developing enabling techniques for two-way relay (TWR) channels experiencing excessive synchronization errors, two conceptually-different schemes are proposed to accommodate any relative misalignment between the signals received at any node. By designing a practical transmission/detection mechanism based on orthogonal frequency division multiplexing (OFDM), the proposed schemes perform significantly better than existing competing solutions. In a related direction, differential modulation is implemented for asynchronous TWR systems that lack the channel state information (CSI) knowledge. The challenge in this problem compared to the conventional point-to-point counterpart arises not only from the asynchrony but also from the existence of an interfering signal. Extensive numerical examples, supported by analytical work, are given to demonstrate the advantages of the proposed schemes. Other important issues considered in this dissertation are related to the extension of the two-way relaying scheme to the multiple-user case, known as the multi-way relaying. First, a distributed source coding solution based on Slepian-Wolf coding is proposed to compress correlated messages close to the information theoretical limits in the context of multi-way relay (MWR) channels. Specifically, the syndrome approach based on low-density parity-check (LDPC) codes is implemented. A number of relaying strategies are considered for this problem offering a tradeoff between performance and complexity. The proposed solutions have shown significant improvements compared to the existing ones in terms of the achievable compression rates. On a different front, a novel approach to channel coding is proposed for the MWR channel based on the implementation of nested codes in a distributed manner. This approach ensures that each node decodes the messages of the other users without requiring complex operations at the relay, and at the same time, providing substantial benefits compared to the traditional routing solution. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

Cette thèse a eu pour objectif d'étudier des questions naturelles de définissabilité autour des transducteurs bidirectionnels.Il est bien connu que les transducteurs bidirectionnels définissent une plus grande classe de transductions que celles des transducteurs unidirectionnels. La première question que nous avons étudiée est donc de décider si un transducteur bidirectionnel est définissable par un transducteur unidirectionnel. Il a été montré en 2013 que cette question est décidable pour des transducteurs fonctionnels (nous montrons aussi en paralèlle que cette question devient indécidable si les transducteurs ne sont plus fonctionnels) mais la complexité de la procédure de décision était non-élémentaire.Nous proposons une caractérisation de la "définissabilité par transducteur unidirectionnel" décidable en espace doublement exponentiel. Cette caractérisation est effective en ce sens qu'elle produit en temps triplement exponentiel le transducteur équivalent. De plus, nous avons étudié ce problème aussi pour les transducteurs "sweeping", pour lesquels la procédure de décision et la construction du transducteur équivalent requièrent une exponentielle de moins. Comme nous avons par ailleurs montré qu'il existe des familles de fonctions réalisables de façon unidirectionnelle avec au minimum deux sauts exponentiels, notre procédure est optimale dans le cas "sweeping".Le fait d'avoir particulièrement étudié les transducteurs"sweeping" nous a poussé à étudier d'autres questions dedéfinissabilité~: est-ce qu'un transducteur donné estréalisable par un transducteur sweeping ? Et par un transducteursweeping réalisant au maximum k passages ? Nous montrons que cesquestions sont décidables avec les mêmes complexitésobtenues précédemment. Comme nous avons montré qu'ilexiste une borne sur le nombre de passages nécéssaires pourréaliser avec un transducteur sweeping une transductiondonnée, cela nous permet aussi de minimiser le nombre de passages d'untransducteur sweeping.Enfin nous avons cherché à caractériser la classe destransductions sweeping dans d'autres modèles de transductions,les Streaming String Transducers (SST) et lestransductions MSO. Cela a en autres permis, en établissant unecorrespondance entre le nombre de passages des transducteurssweeping et le nombre de registres d'une sous-classe de SST, deminimiser le nombre de registres pour une classe intéressantede SST. Dans l'ensemble, notre travail a permis de couvrir l'ensembledes relations entre ces modèles, et les questions dedéfinissabilité qui se posent naturellement. / The goal of this thesis was to study definability questionsabout finite-state transducers and in particular two-waytransducers. It is known that two-way transducers cover a larger classof transductions than one-way transducers. Then the first question wetackled is the one-way definability problem: is it possible torealize a given two-way transduction by a one-way transducer? Thisproblem was shown to be decidable for functionaltransducers (we also show as a side result that one-way definability becomes undecidable for non-functional transducers) but the decision procedure had non-elementary complexity.We proposed a characterization of one-way definability thatallows us to decide it in double-exponential space, and provide anequivalent one-way transducer of triple-exponential size. We firststudied this question for a restricted class, namely sweepingtransducers, for which the decision procedure and the construction ofthe one-way transducer take one less exponential. For suchtransducers, our procedure is optimal in the sense that we have shownthat there exists a family of functions that are one-way definable andfor which an equivalent one-way transducer requires doubly exponentialsize.The study of sweeping transducers raised other definability questions: Is a given transducer equivalent to some sweeping transducer? And to some sweeping transducer that performs at most k passes? We showed that those questions are decidable and the decision procedure, as well as the equivalent transducer, have the same complexity as in the one-way case. Moreover, as we have shown that there exists a bound on the number of passes required to realize a transduction by a sweeping transducer, we managed to obtain a procedure to minimize the number of passes of a sweeping transducer.Finally we tried to characterize sweeping transducers in other models for regular transductions such as Streaming String transducers (SST) and MSO transductions. As we obtained an equivalence between the number of passes of a sweeping transducer and the number of registers of the equivalent SST we provided a minimization procedure for the number of registers of a large class of SST's. To conclude, our work allowed us to provide a good overall understanding of the definability questions between the models for regular transductions and in particular regarding the resources, whether it is the number of passes (and of course one-way definability is crucial in that aspect) or the number of registers.

An innovative strengthening technique is applied for the first time in this study to provide flexural strengthening in two-way reinforced concrete (RC) slabs supported on edge beams. The technique comprises external bonding of textiles on the tension face of RC slabs through the use of polymer-modified cement- based mortars. The textiles used in the experimental campaign comprised fabric meshes made of long stitch-bonded fibre rovings in two orthogonal directions. The specimens measured 2 x 2 m in plan and were supported on hinges at the corners. Three RC slabs strengthened by textile reinforced mortar (TRM) overlays and one control specimen were tested to failure. One specimen received one layer of carbon fibre textile, another one received two, whereas the third specimen was strengthened with three layers of glass fibre textile having the same axial rigidity (in both directions) with the single-layered carbon fibre textile. All specimens failed due to flexural punching. The load-carrying capacity of the strengthened slabs was increased by 26%, 53%, and 20% over that of the control specimen for slabs with one (carbon), two (carbon) and three (glass) textile layers, respectively. The strengthened slabs showed an increase in stiffness and energy absorption. The experimental results are compared with theoretical predictions based on existing models specifically developed for two-way slabs and the performance of the latter is evaluated. Based on the findings of this work the authors conclude that TRM overlays comprise a very promising solution for the strengthening of two-way RC slabs.

Members of the Instructional Teleconference Consortium (ITC) were mailed a survey instrument. A total list of 375 teleconference coordinators generated 137 usable responses. The purposes of this study of faculty and staff development presentations by teleconferencing were to determine the amount of usage; which subject areas are utilized; what delivery methods (live, interactive, prerecorded, multimedia, etc.) are utilized; barriers (size or location of college, size of teleconference or travel budget, etc.) to implementing teleconferences; and the sources of presentations utilized in teleconferences. Larger community colleges are the greater users of teleconferencing and even produce some for distribution to other community colleges, whereas smaller community colleges have just begun to receive equipment that enables them to receive telecasts for this purpose. No clear subject area has yet been defined that dominates these teleconferences, and the trend is toward two-way audio and one-way video as the delivery media as communication costs decline. Barriers of money for staff, equipment, and programming appear to be the principal objections to the use of teleconferencing for faculty and staff development presentations. There appear to be few sources of presentations except for the Public Broadcasting System (PBS).

Background Physics-based snow simulation in real time is an unexplored area, the reason being the difficulty introduced by the multitude of factors that affect the snow behaviour, such as cohesion, thermodynamics, and compression. Simulating snow in real time when considering these factors can become computationally demanding. However, the continued advancement of graphics processing units makes the exploration of real-time snow simulation attractive. Recently published research on real time physics-based snow simulation shows promising results in a parallel solution and will serve as motivation and base for this thesis. Objectives This thesis aims to improve the time-step of a previously proposed method using an iterative method and improve the snow behaviour with a particle-based boundary handling implementation. The aim consists of the following objectives. Integrate an iterative method, extend the snow behaviour with additional snow types, and implement a particle-based boundary handling method with two-way coupling. The proposed method should remain comparable to the original method in terms of snow behaviour. In order to gather results, the methods are measured in performance and used in a questionnaire to analyse the behaviour. Methods An iterative method along with a particle-based boundary handling method is implemented. The methods are both measured and compared using quantitative tests. Additionally, a questionnaire is deployed to gather qualitative results about the behaviour of the snow. Results The proposed method outperforms the original method in terms of time-step size. The proposed method is capable of increasing the time-step tenfold while decreasing the execution time by approximately eight times. Finally, the results from the questionnaire verify the perceived naturalism of the snow and its comparability to the original method. Conclusions The proposed method can perform with an increased time-step and a lower execution time compared to the original method, at the cost of time spent per frame. Lastly, the snow is perceived as natural with the boundary handling method at a significance level of 1 %. / Bakgrund Fysikbaserad snösimulering i realtid är ett outforskat område, anledning till detta är mängden faktorer som påverkar snö, exempelvis sammanhållning, termodynamik och kompression. Simulering av snö i realtid som tar hänsyn till dessa faktorer kan bli beräkningsmässigt krävande, däremot har den växande utvecklingen av grafikprocessorer gjort utforskning av realtidsmetoder ytterligare attraktivt. Nyligen publicerad forskning inom fysikbaserade snösimuleringar i realtid visar lovande resultat i en parallell lösning och kommer att användas som motivering samt bas i detta examensarbete. Syfte Detta examensarbete syftar till att förbättra tidsstegen i en tidigare implementerad metod med hjälp av att använda ett iterativt tillvägagångssätt samt förbättra snöbeteendet med en partikelbaserad gränshanteringsimplementation. Syftet är uppdelat i följande mål. Integrera en iterativ metod, utöka snöbeteendet med ytterligare snötyper, och implementera en partikelbaserad gränshanteringsmetod med tvåvägskoppling. Den föreslagna metoden ska förhålla sig jämförbar med originalmetoden med avseende på snöbeteendet. Slutligen för att samla in resultat mäts metoderna i prestanda och dessutom används ett frågeformulär för att analysera beteendet. Metod En iterativ metod tillsammans med en partikelbaserad gränshanteringsmetod är implementerad. Båda metoderna mäts och jämförs med hjälp av kvantitativa tester. Dessutom distribueras ett kvalitativt frågeformulär för att samla resultat om snöns beteende.  Resultat Den föreslagna metoden tillåter större tidsteg än originalmetoden. Den iterativa metoden är kapabel till att förstora tidsstegen tiofaldigt, samtidigt som den sänker exekveringstiden till en åttondel. Resultaten verifierar den uppfattade naturligheten av snön och jämförelsebarheten till originalmetoden. Slutsatser Den föreslagna metoden kan prestera med ett större tidssteg och en lägre exekveringstid jämfört med originalet i utbyte av högre tid spenderad per bildruta. Slutligen uppfattas snön som naturlig i sammankoppling med gränshanteringsmetoden vid en signifikansnivå på 1 %.

In this thesis I capture the effect of oil prices on the economic growth of net oil exporters and net oil importers of the world. The existing literature on this topic only covers some parts of the world, major oil exporters and oil importers and some covers only a single country. So, in this work I take a larger set of countries and enlarge the time period. This work covers the time period 1972-2021. The effect is examined by using the pooled OLS and two way fixed effect. I get significant results for both the net oil exporters and net oil importers. The results of both net oil exporters and net oil importers are significantly different from zero. But these results are opposite from the existing literature. I found that an increase in oil price has a negative impact on the economic growth of net oil exporters, but it has a positive effect on the economic growth of net oil importers. So, these results also do not support the theoretical and empirical literature.

Two way left turn lanes (TWLTL) and raised medians are common median treatments on roadways. This research focused on evaluating the safety effectiveness of conversion of TWLTLs into raised medians using Before-After and Cross Sectional Studies. In the Before-After Studies, we evaluated the effect of this treatment using the Naive, Before-After with Comparison Group (CG), and Before-After with Empirical Bayes (EB) Methods. In order to apply these methods, a total of 33 segments of a treated group and 109 segments of a comparison group have been collected. Also, safety performance functions (SPFs) have been developed using the negative binomial model in order to calibrate crash modification factors (CMF) using the Before-After with Empirical Bayes Method. This research also evaluated the safety effectiveness of this treatment on four and six lane roads using Before-After with CG and Before-After with EB. The type of raised medians was further evaluated using Before-After with CG and EB. In sum, the results from this study show that applying the before-After and Cross Sectional studies have proved that the conversion from a TWLTL to a raised median helped to reduce total, fatal and injury, head on, angle, and left turn crashes. It significantly reduces crashes for head-on and left turn crashes, by restricting turning maneuvers. Also, this study has proved that the treatment is more effective on four rather than six lane roads. Furthermore, two types of raised medians, concrete and lawn curb, were evaluated after the conversion from TWLTLs. It was found that both medians have similar effects due to the conversion, and both median types helped in reducing the number of crashes.

Educators of students with moderate and severe intellectual disabilities face a significant challenge in preparing their students while in school to function, acquire, and maintain skills that would facilitate successful performance in the workforce while in supported and/or independent employment after graduation. The field of special education still debates about the best way to teach students with moderate intellectual disabilities, the best setting for their instruction and the best instructional schedule. The current research investigated the effectiveness and efficiency of three instructional schedules in the skill acquisition and generalization of two-way radio usage to report task completion by high school students with moderate intellectual disabilities. The instructional schedules investigated were: (a) community-based instruction only (CBI), (b) community based instruction plus simulated instruction in the classroom-same day (CBISC) and (c) simulated instruction in the classroom only (SICO). A Multiple Probe Design across participants with intermittent probe trials within each instructional group, and an added generalization phase (Horner & Baer, 1978; Tawney & Gast, 1984; Alberto & Troutman, 2003) was employed in this study. Nine high school students with moderate intellectual disabilities, three in each instructional schedule, were taught to use a two-way radio to report task completion. The results of the study revealed that the CBI instructional schedule was the overall most efficient instructional schedule for skill acquisition. Two of the CBI participants required the least number of trials to learn to use a two-way radio to report task completion. The second most efficient schedule was the CBISC and the least efficient instructional schedule was the SICO. Based on Mean scores, learning efficiency appeared to be greater for the participants in the CBI and CBISC instructional schedule. These participants required the least number of intrusive prompts. Results indicated that the SICO instructional scheduled was more efficient for only one participant. This participant only required verbal prompts for acquisition of the skill. However, participant one on the SICO instructional schedule required the most intrusive prompts of all participants across groups. For generalization, the CBISC instructional schedule appeared to be the most effective. In this schedule, the two participants that concluded the study generalized the skill across three novel settings with 100% accuracy. The SICO schedule, also had two participants generalized the skill across three novel settings; however, one participant in that group failed to generalize the skill in two settings. The CBI instructional schedule appeared to be the least effective for skill generalization in this study. In this schedule, only one participant generalized the skill in all three novel settings.

This thesis investigates a parametric study of a flat plate floor system designed using post-tensioning. The load balanced by the post-tensioning, the slab depth, and the strength of concrete were varied to create the parametric study of a hotel/condominium grid layout. In order to perform the parametric study, research was conducted on the development of post-tensioning, methods of analysis for two-way slab design, and post-tensioning methods of analysis. Design was conducted by hand through a series of Excel spreadsheets and compared to results found using the computer analysis program, ADAPT-PT. The designs found in the parametric study were then used to perform a cost analysis across ten cities in the United States: Atlanta, Boston, Chicago, Denver, Houston, Los Angeles, Miami, Phoenix, San Francisco, and Seattle. The designs from the hand analysis and the ADAPT-PT model provided similar results for the post-tensioning, and both methods provide an adequate design. The use of ADAPT-PT is recommended because of its ease of use and quick calculation capabilities. The designs of the hand analysis were quantified and along with unit prices gathered from contractors and suppliers the cost analysis found that the design with 100% of the dead load balanced provided the least expensive solution for all the cities, and the design using a 6000 psi strength concrete provide the most expensive solution for all cities. The least expensive slab design was $9.02 per square foot in Atlanta, Georgia, and the most expensive slab design was $24.96 per square foot in Miami, Florida. A more rigorous parametric study in the future may provide a better optimization for the hotel/condominium slab investigated as the parametric study of this thesis found costs which varied by less than 10% between the most expensive and least expensive slabs in the ten cities.