Peak -to -average power ratio reduced parallel interference cancellation Multicarrier-Code Division Multiple Access system with anti -interference property

Orthogonal Frequency-Division Multiplexing (OFDM) has been proved to be a promising technology that enables the transmission of higher data rate. Multicarrier Code-Division Multiple Access (MC-CDMA) is a transmission technique which combines the advantages of both OFDM and Code-Division Multiplexing Access (CDMA), so as to allow high transmission rates over severe time-dispersive multi-path channels without the need of a complex receiver implementation. Also MC-CDMA exploits frequency diversity via the different subcarriers, and therefore allows the high code rates systems to achieve good Bit Error Rate (BER) performances. Furthermore, the spreading in the frequency domain makes the time synchronization requirement much lower than traditional direct sequence CDMA schemes. There are still some problems when we use MC-CDMA. One is the high Peak-to-Average Power Ratio (PAPR) of the transmit signal. High PAPR leads to nonlinear distortion of the amplifier and results in inter-carrier self-interference plus out-of-band radiation. On the other hand, suppressing the Multiple Access Interference (MAI) is another crucial problem in the MC-CDMA system. Imperfect cross-correlation characteristics of the spreading codes and the multipath fading destroy the orthogonality among the users, and then cause MAI, which produces serious BER degradation in the system. Moreover, in uplink system the received signals at a base station are always asynchronous. This also destroys the orthogonality among the users, and hence, generates MAI which degrades the system performance. Besides those two problems, the interference should always be considered seriously for any communication system. In this dissertation, we design a novel MC-CDMA system, which has low PAPR and mitigated MAI. The new Semi-blind channel estimation and multi-user data detection based on Parallel Interference Cancellation (PIC) have been applied in the system. The Low Density Parity Codes (LDPC) has also been introduced into the system to improve the performance. Different interference models are analyzed in multi-carrier communication systems and then the effective interference suppression for MC-CDMA systems is employed in this dissertation. The experimental results indicate that our system not only significantly reduces the PAPR and MAI but also effectively suppresses the outside interference with low complexity. Finally, we present a practical cognitive application of the proposed system over the software defined radio platform.

The Structure of Games

Computer Game Playing has been an active area of research since Samuel’s first Checkers player (Samuel 1959). Recently interest beyond the classic games of Chess and Checkers has led to competitions such as the General Game Playing competition, in which players have no beforehand knowledge of the games they are to play, and the Computer Poker Competition which force players to reason about imperfect information under conditions of uncertainty. The purpose of this dissertation is to explore the area of General Game Playing both specifically and generally. On the specific side, we describe the design and implementation of our General Game Playing system OGRE. This system includes an innovative method for feature extraction that helped it to achieve second and fourth place in two international General Game Playing competitions. On the more general side, we also introduce the Regular Game Language, which goes beyond current works to provide support for both stochastic and imperfect information games as well as the more traditional games.

Peak-to-Average Power Ratio Reduced Parallel Interference Cancellation Multicarrier-Code Division Multiple Access System with Anti-Interference Property

Orthogonal Frequency-Division Multiplexing (OFDM) has been proved to be a promising technology that enables the transmission of higher data rate. Multicarrier Code-Division Multiple Access (MC-CDMA) is a transmission technique which combines the advantages of both OFDM and Code-Division Multiplexing Access (CDMA), so as to allow high transmission rates over severe time-dispersive multi-path channels without the need of a complex receiver implementation. Also MC-CDMA exploits frequency diversity via the different subcarriers, and therefore allows the high code rates systems to achieve good Bit Error Rate (BER) performances. Furthermore, the spreading in the frequency domain makes the time synchronization requirement much lower than traditional direct sequence CDMA schemes. There are still some problems when we use MC-CDMA. One is the high Peak-to-Average Power Ratio (PAPR) of the transmit signal. High PAPR leads to nonlinear distortion of the amplifier and results in inter-carrier self-interference plus out-of-band radiation. On the other hand, suppressing the Multiple Access Interference (MAI) is another crucial problem in the MC-CDMA system. Imperfect cross-correlation characteristics of the spreading codes and the multipath fading destroy the orthogonality among the users, and then cause MAI, which produces serious BER degradation in the system. Moreover, in uplink system the received signals at a base station are always asynchronous. This also destroys the orthogonality among the users, and hence, generates MAI which degrades the system performance. Besides those two problems, the interference should always be considered seriously for any communication system. In this dissertation, we design a novel MC-CDMA system, which has low PAPR and mitigated MAI. The new Semi-blind channel estimation and multi-user data detection based on Parallel Interference Cancellation (PIC) have been applied in the system. The Low Density Parity Codes (LDPC) has also been introduced into the system to improve the performance. Different interference models are analyzed in multi-carrier communication systems and then the effective interference suppression for MC-CDMA systems is employed in this dissertation. The experimental results indicate that our system not only significantly reduces the PAPR and MAI but also effectively suppresses the outside interference with low complexity. Finally, we present a practical cognitive application of the proposed system over the software defined radio platform.

Engineering Analysis in Imprecise Geometric Models

Engineering analysis in geometric models has been the main if not the only credible/reasonable tool used by engineers and scientists to resolve physical boundaries problems. New high speed computers have facilitated the accuracy and validation of the expected results. In practice, an engineering analysis is composed of two parts; the design of the model and the analysis of the geometry with the boundary conditions and constraints imposed on it. Numerical methods are used to resolve a large number of physical boundary problems independent of the model geometry. The time expended due to the computational process are related to the imposed boundary conditions and the well conformed geometry. Any geometric model that contains gaps or open lines is considered an imperfect geometry model and major commercial solver packages are incapable of handling such inputs. Others packages apply different kinds of methods to resolve this problems like patching or zippering; but the final resolved geometry may be different from the original geometry, and the changes may be unacceptable. The study proposed in this dissertation is based on a new technique to process models with geometrical imperfection without the necessity to repair or change the original geometry. An algorithm is presented that is able to analyze the imperfect geometric model with the imposed boundary conditions using a meshfree method and a distance field approximation to the boundaries. Experiments are proposed to analyze the convergence of the algorithm in imperfect models geometries and will be compared with the same models but with perfect geometries. Plotting results will be presented for further analysis and conclusions of the algorithm convergence

Inflation, currency substitution, and dollarization : the case of Argentina

This dissertation discusses the relationship between inflation, currency substitution and dollarization that has taken place in Argentina for the past several decades. First, it is shown that when consumers are able to hold only domestic monetary balances (without capital mobility) an increase in the rate of inflation will produce a balance of payments deficit. We then look at the same issue but with heterogeneous consumers, this heterogeneity being generated by non-proportional lump-sum transfers. Second, we discussed some necessary assumptions related to currency substitution models and concluded that there was no a-priori conclusion on whether currencies should be assumed to be "cooperant" or "non-cooperant" in utility. That is to say, whether individuals held different currencies together or one instead of the other. Third, we went into discussing the issue of currency substitution as being a constraint on governments inflationary objectives rather than a choice of those governments to avoid hyperinflations. We showed that imperfect substitutability between currencies does not "reduce the scope for rational (hyper)inflationary processes" as it had been previously argued. It will ultimately depend on the parametrization used and not on the intrinsic characteristics of imperfect substitutability between currencies. We further showed that in Argentina, individuals have been able to endogenize the money supply by holding foreign monetary balances. We argued that the decision to hold foreign monetary balances by individuals is always a second best due to the trade-off between holding foreign monetary balances and consumption. For some levels of income, consumption, and foreign inflation, individuals would prefer to hold domestic monetary balances rather than foreign ones. We then modeled the distinction between dollarization and currency substitution. We concluded that although dollarization is necessary for currency substitution to take place, the decision to use foreign monetary balances for transactions purposes is largely independent from the dollarization process. Finally, we concluded that Argentina should not fully dollarize its economy because dollarization is always a second best to using a domestic currency. Further, we argued that a fixed exchange system would be better than a flexible exchange rate or a "crawling-peg" system because of the characteristics of the political system and the possibilities of "mass praetorianism" to develop, which is intricately linked to "populist" solutions.

Radiocarbon dating, carbon storage and soil properties of samples from Tulemalu Lake, central Canadian Arctic

We investigated total storage and landscape partitioning of soil organic carbon (SOC) in continuous permafrost terrain, central Canadian Arctic. The study is based on soil chemical analyses of pedons sampled to 1 m depth at 35 individual sites along three transects. Radiocarbon dating of cryoturbated soil pockets, basal peat and fossil wood shows that cryoturbation processes have been occurring since the Middle Holocene and that peat deposits started to accumulate in a forest-tundra environment where spruce was present (~6000 cal yrs BP). Detailed partitioning of SOC into surface organic horizons, cryoturbated soil pockets and non-cryoturbated mineral soil horizons is calculated (with storage in active layer and permafrost calculated separately) and explored using principal component analysis. The detailed partitioning and mean storage of SOC in the landscape are estimated from transect vegetation inventories and a land cover classification based on a Landsat satellite image. Mean SOC storage in the 0-100 cm depth interval is 33.8 kg C/m**2, of which 11.8 kg C/m**2 is in permafrost. Fifty-six per cent of the total SOC mass is stored in peatlands (mainly bogs), but cryoturbated soil pockets in Turbic Cryosols also contribute significantly (17%). Elemental C/N ratios indicate that this cryoturbated soil organic matter (SOM) decomposes more slowly than SOM in surface O-horizons.

A Data Driven Tool supported CLD Creation Approach

The creation of Causal Loop Diagrams (CLDs) is a major phase in the System Dynamics (SD) life-cycle, since the created CLDs express dependencies and feedback in the system under study, as well as, guide modellers in building meaningful simulation models. The cre-ation of CLDs is still subject to the modeller's domain expertise (mental model) and her ability to abstract the system, because of the strong de-pendency on semantic knowledge. Since the beginning of SD, available system data sources (written and numerical models) have always been sparsely available, very limited and imperfect and thus of little benefit to the whole modelling process. However, in recent years, we have seen an explosion in generated data, especially in all business related domains that are analysed via Business Dynamics (BD). In this paper, we intro-duce a systematic tool supported CLD creation approach, which analyses and utilises available disparate data sources within the business domain. We demonstrate the application of our methodology on a given business use-case and evaluate the resulting CLD. Finally, we propose directions for future research to further push the automation in the CLD creation and increase confidence in the generated CLDs.

Uplink Performance of Conventional and Massive MIMO Cellular Systems with Delayed CSIT

This work studies the uplink of a cellular network with zero-forcing (ZF) receivers under imperfect channel state information at the base station. More specifically, apart from the pilot contamination, we investigate the effect of time variation of the channel due to the relative users' movement with regard to the base station. Our contributions include analytical expressions for the sum-rate with finite number of BS antennas, and also the asymptotic limits with infinite power and number of BS antennas, respectively. The numerical results provide interesting insights on how the user mobility degrades the system performance which extends previous results in the literature.

Calibrated Polarisation Tilt Angle Recovery for Wireless Communications

In this paper, we show how the polarisation state of a linearly polarised antenna can be recovered through the use of a three-term error correction model. The approach adopted is shown to be robust in situations where some multipath exists and where the sampling channels are imperfect with regard to both their amplitude and phase tracking. In particular, it has been shown that error of the measured polarisation tilt angle can be improved from 33% to 3% and below by applying the proposed calibration method. It is described how one can use a rotating dipole antenna as both the calibration standard and as the polarisation encoder, thus simplifying the physical arrangement of the transmitter. Experimental results are provided in order to show the utility of the approach, which could have a variety of applications including bandwidth conservative polarisation sub-modulation in advanced wireless communications systems.

Manual for the monitoring of sea turtles in the Cape Verde Islands

[ES] To actively protect sea turtles on their nesting beaches, it is essential to obtain knowledge about trends in abundance. The way sea turtles live makes it extremely difficult to identify how many individuals there are in a population at any point in time. Due to practical problems, given their entirely marine life with limited visibility and great oceanic dispersal, counting males or juveniles is currently quite difficult and imprecise. Counting females and nests on beaches during the nesting season is the best feasible but still imperfect method, since only an unknown portion of adult females nest every season. It is impossible to know the real number of females in the population by merely counting females and nests in a given year.

Un-Editing Alfred: Rethinking Modern Editions of Pre-modern Texts from a Post-modern Sensibility

Thesis (Ph.D.)--University of Washington, 2016-06

Building peace by supporting post-conflict electoral processes

Les élections post-conflit ou élections de sortie de crise organisées sous l’égide de la communauté internationale en vue de rétablir la paix dans les pays sortant de violents conflits armés ont un bilan mixte caractérisé par le succès ou l’échec selon les cas. Ce bilan mitigé représente le problème principal auquel cette recherche tente de répondre à travers les questions suivantes : l’assistance électorale étrangère est-elle efficace comme outil de rétablissement de la paix dans les sociétés post-conflit? Qu’est ce qui détermine le succès ou l’échec des élections post-conflit à contribuer efficacement au rétablissement de la paix dans les sociétés déchirées par la guerre? Pour résoudre cette problématique, cette thèse développe une théorie de l’assistance électorale en période post-conflit centrée sur les parties prenantes à la fois du conflit armé et du processus électoral. Cette théorie affirme que l’élément clé pour le succès des élections post-conflit dans le rétablissement de la paix est le renforcement de la capacité de négociation des parties prenantes à la fois dans le processus de paix et dans le processus électoral post-conflit. Dans les situations post-conflit, une assistance électorale qui se voudrait complète et efficace devra combiner à la fois le processus électoral et le processus de paix. L’assistance électorale sera inefficace si elle se concentre uniquement sur les aspects techniques du processus électoral visant à garantir des élections libres, transparentes et équitables. Pour être efficace, l’accent devra également être mis sur les facteurs supplémentaires qui peuvent empêcher la récurrence de la guerre, tels que l’habilité des individus et des groupes à négocier et à faire des compromis sur les grandes questions qui peuvent menacer le processus de paix. De fait, même des élections transparentes comme celles de 1997 au Liberia saluées par la communauté internationale n’avaient pas réussi à établir des conditions suffisantes pour éviter la reprise des hostilités. C’est pourquoi, pour être efficace, l’assistance électorale dans les situations de post-conflit doit prendre une approche globale qui priorise l’éducation civique, la sensibilisation sur les droits et responsabilités des citoyens dans une société démocratique, le débat public sur les questions qui divisent, la participation politique, la formation au dialogue politique, et toute autre activité qui pourrait aider les différentes parties à renforcer leur capacité de négociation et de compromis. Une telle assistance électorale fera une contribution à la consolidation de la paix, même dans le contexte des élections imparfaites, comme celles qui se sont détenues en Sierra Leone en 2002 ou au Libéria en 2005. Bien que la littérature sur l’assistance électorale n’ignore guère l’importance des parties prenantes aux processus électoraux post-conflit (K. Kumar, 1998, 2005), elle a fortement mis l’accent sur les mécanismes institutionnels. En effet, la recherche académique et professionnelle est abondante sur la réforme des lois électorales, la reforme constitutionnelle, et le développement des administrations électorales tels que les commissions électorales, ainsi que l’observation électorale et autres mécanismes de prévention de la fraude électorale, etc. (Carothers & Gloppen, 2007). En d’autres termes, les décideurs et les chercheurs ont attribué jusqu’à présent plus d’importance à la conception et au fonctionnement du cadre institutionnel et des procédures électorales. Cette thèse affirme qu’il est désormais temps de prendre en compte les participants eux-mêmes au processus électoral à travers des types d’assistance électorale qui favoriseraient leur capacité à participer à un débat pacifique et à trouver des compromis aux questions litigieuses. Cette approche plus globale de l’assistance électorale qui replace l’élection post-conflit dans le contexte plus englobant du processus de paix a l’avantage de transformer le processus électoral non pas seulement en une expérience d’élection de dirigeants légitimes, mais aussi, et surtout, en un processus au cours duquel les participants apprennent à régler leurs points de vue contradictoires à travers le débat politique dans un cadre institutionnel avec des moyens légaux et légitimes. Car, si le cadre institutionnel électoral est important, il reste que le résultat du processus électoral dépendra essentiellement de la volonté des participants à se conformer au cadre institutionnel et aux règles électorales.

Reabilitação estética com facetas em pacientes com amelogénese imperfeita

A Amelogénese Imperfeita é uma anomalia hereditária que interfere no desenvolvimento do esmalte, pode variar em seu grau de intensidade, podendo afetar o esmalte tanto na sua qualidade, quanto na sua quantidade e em ambas as dentições. Existem pelo menos catorze subtipos diferentes de amelogénese imperfeita, sendo as do tipo hipoplásico, hipomaturado, hipocalcificado e hipoplásico ou hipomaturado com taurodontia segundo o seu fenótipo e quinze subtipos, segundo o seu modo de transmissão. Segundo a literatura, os pacientes com amelogénese imperfeita, independentemente do subtipo presente, apresentam complicações orais semelhantes: estética dentária comprometida, sensibilidade dentária e diminuição da dimensão vertical de oclusão. O tratamento destes pacientes assume um papel relevante, na medida em que requer cuidados especiais, já que esta doença acarreta, por norma, problemas psicológicos e interfere com o autoestima do individuo. É notória, atualmente, uma oferta variada de opções reabilitadoras ao dispor do Médico Dentista, que ajudarão o mesmo a restabelecer a estética e função. Os tratamentos são variados e por vezes complexos, podem ser desenvolvidos de forma conservadora ou invasiva. Contudo, a escolha do melhor tratamento será consequência da gravidade da patologia e de fatores inerentes ao próprio paciente. Neste estudo, abordamos as facetas, como uma alternativa reabilitadora, que com o avanço e melhorias na área da Dentisteria Estética, nomeadamente no que diz respeito à adesão à dentina, parecem ser uma opção credível. Assim, o objetivo desta dissertação é demonstrar e elucidar a reabilitação dos defeitos associados a esta doença com a utilização de facetas diretas e indiretas. Foram efetuadas pesquisas e consulta de livros, monografias, dissertações, artigos em base de dados como o Pubmed/Medline, para que conseguíssemos realizar uma discussão sobre o mesmo tema e desta forma encontrar uma adequada resposta a todas as nossas inquietações sobre esta questão.

The renormalization group via statistical inference

In physics, one attempts to infer the rules governing a system given only the results of imperfect measurements. Hence, microscopic theories may be effectively indistinguishable experimentally. We develop an operationally motivated procedure to identify the corresponding equivalence classes of states, and argue that the renormalization group (RG) arises from the inherent ambiguities associated with the classes: one encounters flow parameters as, e.g., a regulator, a scale, or a measure of precision, which specify representatives in a given equivalence class. This provides a unifying framework and reveals the role played by information in renormalization. We validate this idea by showing that it justifies the use of low-momenta n-point functions as statistically relevant observables around a Gaussian hypothesis. These results enable the calculation of distinguishability in quantum field theory. Our methods also provide a way to extend renormalization techniques to effective models which are not based on the usual quantum-field formalism, and elucidates the relationships between various type of RG.

Welcome to Lowell National Historical Park.

Includes text and index.