Drilling is one of the important aspects in the oil and gas industry due to the high demand for energy worldwide. Drilling time is considered as the major part of the operations time where the penetration rate (ROP) remains as the main factor for reducing the time. Maximizing ROP to lower the drilling cost is the main aim of operators. However, high ROP if not controlled may impact on the well geometry in terms of wellbore instability, cavities, and hole diameter restrictions. Accordingly, more time is needed for the other operations that follow such as: pool out of hole (POOH), casing running, and cementing. Bit wear is considered as the essential issue that influences in direct way on the bit performance and reduce ROP. Predicting the abrasive bit wear is required to estimate the right time when to POOH to prevent any costly job to fish any junk out to the surface. The two-common types of bits are considered in the research, rock bits (roller cone bits) and Polycrystalline Diamond Compact bits (PDC). This study focuses more on PDC bits because about 60% of the total footage drilled in wells worldwide were drilled by PDC bits and this is expected to reach 80% in 2020. The contribution of this research is to help reducing the drilling cost by developing new tools not to estimating the time when to POOH to surface but also to measure the wear and enhance the accuracy of prediction the bit efficiency. The work is broken down into four main stages or models to achieve the objective: The first stage; estimating of the rock abrasiveness and calculate the dynamic dulling rate of the rock bit while drilling. The second stage; estimating the PDC abrasive cutters wear by driving a new model to determine the mechanical specific energy (MSE), torque, and depth of cut (DOC) as a function of effective blades (EB). The accuracy of the predicted wear achieves 88% compared to the actual dull grading as an average for bits used in five wells. The third stage; modifying the previous MSE tool to develop a more accurate approach; effective mechanical specific energy (EMSE), to predict the PDC bit efficiency in both the inner and outer cone to match the standard bit dulling. The fourth stage; predicting ROP while PDC drilling in hole by accounting three parts of the process: rock drillability, hole cleaning, and cutters wear. The results achieve an enhancement of about 40% as compared to the available previous models. Consequently, the developed models in this study provide a novelty on understanding in more details the bit rock interface process and gain an idea of the relationship between the drilling parameters to enhance the bit performance and avoid damaging the bit. This is basically about optimisation the controllable factors such as: weight on bit (WOB), rotary speed (RPM), and flow rate. The result is the reduction in time losses and the operations cost. To ensure reliability and consistency of the proposed models, they were validated with several vertical oil wells drilled in Libya. The results from the validation of the models are consistent with the real field data. The research concludes that the developed models are reliable and applicable tool for both: to assist decision-makers to know when to pull the bit out to surface, and also to estimate the bit performance and wear.

<p dir="ltr"> Nowadays, inkjet printers are widely used all around the world. But how do they transfer the digital image to a map that can control nozzle firing? In this preliminary report, we briefly illustrate that part of the printing pipeline that starts from a halftone image and ends with Hardware Ready Bits (HRBs). We also describe the implementation of the multi-pass printing method with a designed print mask. HRBs are used to read an input halftone CMY image and output a binary map of each color to decide whether or not to eject the corresponding coloranr drop at each pixel position. In general, for an inkjet printer, each row of the image corresponds to one specific nozzle in each swath so that each swath will be the height of the printhead \cite{torpey1997multipass}. To avoid visible white streaks due to clogged or burned out color nozzles, the method called multi-pass printing is implemented. Subsequently, the print mask is introduced so that we can decide during which pass each pixel should be printed. Once we figure out how to transfer the digital image to our printing signals. We start to think about improving the color performance for the inkjet printer. In one of our previous papers \cite{wang2020developing}, we described the color management pipeline that was applied to our nail inkjet printer, which is used to map the source gamut to the destination printer gamut. However, the resulting prints are not as vivid as we would like to have, since those prints are not well saturated. To obtain more saturated prints, we propose a saturation enhancement method based on image segmentation and hue angle. This method will not necessarily give us the closest representation of the colors within the input image but could give us more saturated prints. The main idea of our saturation enhancement method is to keep the lightness and hue constant, while stretching the chroma component.</p><p><br></p><p dir="ltr"> In one of our previous papers \cite{hu2021improving}, we mostly focused on the color saturation problem in our inkjet printer. However, our partner reported that there are some boundary noise pixels on the background, which are quite visible when the background is white. By checking the pipeline of our printing procedure, we realized that the noise stray dots are generated during the halftoning procedure. This part of the dissertation is dedicated to separating the white background from the foreground, which enables us to constrain the error diffusion process inside the white background. The main idea is to apply image segmentation, which could help us to precisely extract the background.</p><p><br></p><p dir="ltr"> Lastly, inspired by the paper \cite{smith2023chiral}, we decided to design an aperiodic clustered-dot screen, which may have better performance compared to the current DBS screen. This screen generation method is offline, so the time cost is not our main consideration. The output halftone result is what we concentrate on. This screen is generated based on a polygon shape, which is called tile(1,1) defined by the paper \cite{smith2023chiral}. We keep extending this single polygon shape to obtain the combination aperiodic shape that is called a supertile. After obtaining the final supertile, we assigned each tile(1,1) shape to either a dot or a hole based on the complementary symmetry property. Finally, based on some interpolation methods, we generate the threshold matrix. </p>

<p>Foreign Direct investment (FDI) has been recognized as a vital source of development for African countries, which are mainly capital importing countries. This has led to a quest for effective regulation of the activities of foreign investors in a country while considering the profit making goals of the investors as well. As there is a need to strike a balance between the need to regulate entry and activities of investors and reaping the immense benefits of FDI such as growth and development. The regulation of FDI thus becomes important. However, there is no universal multilateral agreement on Investment (MAI) that binds most states oft the world. What we have is attempts at regional levels to regulate Investment uniformly. This quest has led to debates with many developing countries (Africa Inclusive) resisting attempts to formulate a MAI. This paper will start with an introduction of the importance of FDI as well as the various attempts that have been made to regulate FID on a multilateral level. Then the paper will go on to examine two Bilateral Investment Treaties (BITs) Botswana-China BIT on Promotion and Protection of Investments 2000,Czech-Tunisia BIT for the Promotion and Reciprocal Protection of Investment 1997, and two Free Trade Agreements (FTAs) - Chapter 11 of the North American Free Trade Agreement (NAFTA), 1990 and the investment provisions of the U.S &ndash / Morocco Free Trade Agreement 2004, to identify those trends that are common to these agreements that have been entered into by African countries. It will examine these provisions in line with the rights and obligations they create for the investors as well as the host countries.</p>

La géométrie de l’information est la théorie mathématique qui applique les méthodes de la géométrie différentielle dans le domaine des statistiques et de la théorie de l’information. C’est une technique très prometteuse pour l’analyse et l’illustration des algorithmes itératifs utilisés en communications numériques. Cette thèse porte sur l’application de cette technique ainsi que d’autre technique d’optimisation bien connue, l’algorithme itératif du point proximal, sur les algorithmes itératifs en général. Nous avons ainsi trouvé des interprétations géométriques (basée sur la géométrie de l’information) et proximales (basée sur l’algorithme du point proximal)intéressantes dans le cas d’un algorithme itératif de calcul de la capacité des canaux discrets sans mémoire, l’algorithme de Blahut-Arimoto. L’idée étant d’étendre cette application sur une classe d’algorithmes itératifs plus complexes. Nous avons ainsi choisi d’analyser l’algorithme de décodage itératif des modulations codées à bits entrelacés afin de trouver quelques interprétations et essayer de proposer des liens existant avec le critère optimal de maximum de vraisemblance et d’autres algorithmes bien connus dans le but d’apporter certaines améliorations par rapport au cas classique de cet algorithme, en particulier l’étude de la convergence.Mots-clefs : Géométrie de l’information, algorithme du point proximal, algorithme de Blahut-Arimoto, décodage itératif, Modulations codées à bits entrelacés, maximum de vraisemblance. / Information geometry is a mathematical theory that applies methods of differential geometryin the fields of statistics and information theory. It is a very promising technique foranalyzing iterative algorithms used in digital communications. In this thesis, we apply this technique, in addition to the proximal point algorithm, to iterative algorithms. First, we have found some geometrical and proximal point interpretations in the case of an iterative algorithmfor computing the capacity of discrete and memoryless channel, the Blahut-Arimoto algorithm.Interesting results obtained motivated us to extend this application to a larger class of iterative algorithms. Then, we have studied in details iterative decoding algorithm of Bit Interleaved Coded Modulation (BICM) in order to analyse and propose some ameliorations of the classical decoding case. We propose a proximal point interpretation of this iterative process and find the link with some well known decoding algorithms, the Maximum likelihood decoding.

O objeto do presente trabalho é a análise das mudanças no regime jurídico do investimento estrangeiro ocorridas na última década. Após o estudo histórico sobre o desenvolvimento desse regime, as quatro tendências que conduziram a elaboração das regras daquele período são examinadas. A primeira delas foi a criação de regimes regionais, como as regras sobre o investimento internacional do NAFT A, ASEAN, APEC e Mercosul. A segunda, as tentativas de estabelecimento de um regime multilateral, como comprovam não só as negociações do MAI e das TRIM\'s, nos quadros da OCDE e OMC, como a consolidação pelo Banco Mundial das Diretivas sobre o investimento direto estrangeiro. Em terceiro lugar, o surgimento de normas internacionais setoriais, a exemplo do Tratado da Carta da Energia. E, por último, o crescimento extraordinário do número de acordos bilaterais sobre a matéria. O estudo leva em consideração a jurisprudência internacional, principalmente as sentenças proferidas pelo CIRDI. O exame dessas quatro tendências é seguido pelo estudo de dois regimes regionais que dizem respeito aos interesses brasileiros: o do Mercosul e o da ALCA. Se comparado com os regimes anteriores, aquele dos anos 90 se distingue por privilegiar a flexibilização das regras sobre o fluxo de capitais e o incremento de seu ganho. Preocupações com regras concernentes à proteção do investimento estrangeiro parecem estar ultrapassadas em razão de dois motivos. Inicialmente, pela implementação de seguros e garantias contra riscos políticos que, além de contornar o risco decorrente das interferências governamentais nos investimentos, também minimizou as discussões sobre as indenizações. Em segundo lugar, pelo endosso dado pela maioria dos países em desenvolvimento às políticas neoliberais -o que inibiu a ação governamental no regime doméstico do investimento internacional- e pela concorrência entre esses países em atrair esse investimento. O direito internacional dos investimentos passou a contar com poucas lacunas, a basear-se menos no costume e a formalizar-se em instrumentos. Questões vitais em décadas anteriores, como aquelas relativas à cláusula Calvo e aos critérios indenizatórios, foram resolvidas por tratados ou pela jurisprudência. Esta tomou-se abundante, consolidando um entendimento conservador. Objetivamente, pouco restou do discurso inflamado dos anos 60 e 70 sobre a NOEI. Desmontou-se o binômio investimento e desenvolvimento, desarticulando-se um sistema anterior chamado de Direito Internacional do Desenvolvimento. Essa desarticulação deu-se por caminhos diversos. O direito internacional dos investimentos, antes objeto de Resolução da ONU, teve seus debates transpostos para outras organização, como o Banco Mundial A preocupação com o desenvolvimento foi realocada de capítulo do Direito Econômico Internacional para o campo dos Direitos Humanos. Das quatro tendências acima, uma delas parece que não terá continuidade: o tratamento setorial da matéria. Todavia, nos próximos anos, as outras três continuarão a ser seguidas: não há indicação de refluxo nos acordos bilaterais; a busca por um regime multilateral irá continuar, como aponta o compromisso assumido na reunião da OMC, em Doha de assinatura das TR!M\'S em 2005; e, finalmente, as negociações da ALCA, que incluem disposições sobre investimentos, indicam continuidade na tendência regional. / The purpose of this work is to analyze the changes introduced in the international legal regime applicable to foreign investment in the last decade. After an historical study on the development of this regime, the four trends that shaped the elaboration of these rules during this period are examined. Firstly, the tendency to the creation of international regional regimes -like NAFTA, Mercosur, ASEAN and APEC\'s special rules on investment- is analyzed. Secondly, the several attempts to establish a multilateral regime on foreign investment -as evidenced by the negotiation of the MAL in the OECD, and of the TRIM\'s, in the WTO, as well as the edition of the Guidelines on Foreign Direct Investment by the Word Bank- are reviewed. In the third place, the international rules applicable to investments in special sectors, as is the case of the Energy Chart Treaty, are focused. Finally, the increase in number of the bilateral treaties is examined. This study takes into account the international jurisprudence, mainly the awards rendered by the lCSID. This exam is followed by the study of two regional regimes that affect Brazilian interests: the Mercosur and the FTAA. If compared with the previous regimes, the one that prevailed in the nineties appears to be more concerned with both the flexibility of the rules on the flow of capitals and the increase of earnings. Concerns about rules on the investment protection have vanished for two main reasons. Initially, the availability of insurance and guaranties against political risks besides minimizing the risks presented by any governmental interference on the investor\'s control over its investment, also contributes to make issues on the value of indemnities irrelevant. In the second place, the majority of the developing countries not just endorsed neo-liberal policies, which made governmental restrictive postures on foreign investment difficult, but have started to compete against each other to attract foreign capitals. The International Law on Investments turned into a system with few gaps, based rather on written treaties than on customary law. Crucial issues of the past few decades, like these related to the Calvo doctrine or to indemnities criteria, were solved by treaties and arbitral decisions. Not only did the jurisprudence become abundant, but also consolidated conservative views on the matter. Objectively, very little remained of the fiery speech on the NEIO. The dual investment and development was undone and the previous system of the International Law of Development collapsed. This collapse was caused by different reasons. The most determining, however, is the fact that the International Law on Investment, based before on customary roles and precariously settled by UN\'s resolutions, were relocated to different fora, like the World Bank. The concern with development switched from an important chapter of the International Economic Law to Human Rights\' domain. Amidst the four trends pointed out in this work, apparently just one will be discontinued in the near future: the sectorial treatment of foreign investment. Nonetheless, the others will continue to be present: there is no evidence of reflux in the signing of bilateral treaties; the search for a multilateral regime will continue, as shown in the commitment made in the WTO Conference of Doha, in 2001, fixing for 2005 the signing of the agreement on TRIM\'s; and finally, the negotiation of FTAA, including dispositions on investments, indicates that the regional tendency will remain.

Submitted by Hellen Luz (hellencrisluz@gmail.com) on 2017-09-04T16:05:51Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Regenerador3RTotalmente.pdf: 2919327 bytes, checksum: 5fbe6ee3c460a8bfd7320e6b53e317f6 (MD5) / Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-09-12T15:09:27Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Regenerador3RTotalmente.pdf: 2919327 bytes, checksum: 5fbe6ee3c460a8bfd7320e6b53e317f6 (MD5) / Made available in DSpace on 2017-09-12T15:09:27Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Regenerador3RTotalmente.pdf: 2919327 bytes, checksum: 5fbe6ee3c460a8bfd7320e6b53e317f6 (MD5) Previous issue date: 2017-05-26 / O presente trabalho teve como objetivo investigar por meio de simulações numéricas, um dispositivo capaz de realizar uma regeneração 3R (Reamplificação, Ressincronização e Reformatação) de maneira totalmente óptica dos sinais propagados em um sistema de comunicação por fibra óptica com taxa de bit de 10 Gbit/s, potência de transmissão inicial de 0 dBm e comprimento de onda de 1550 nm. Como aliados ao processo de regeneração, utilizou-se os efeitos dispersivos e os não lineares de automodulação de fase (Self-Phase Modulation - SPM), modulação de fase cruzada (Cross-Phase Modulation - XPM) e mistura de quatro ondas (Four – Wave Mixing - FWM) em um interferômetro de Mach-Zehnder, cujo um dos braços é composto por uma fibra de cristal fotônico altamente não linear (HNL-PCF). As simulações foram realizadas através do software comercial OptiSystem da empresa canadense Optiwave Corporation. O desempenho do sistema foi analisado através da comparação entre os valores do fator de qualidade (fator Q), da taxa de erro de bit (BER), do espectro óptico e da relação sinal ruído óptico (OSNR) dos sinais regenerados, pré-regenerados e degradados na entrada e na saída do sistema proposto. Através deste projeto foi possível obter uma regeneração eficiente do sinal, com valores ótimos de OSNR, de fator de qualidade (fator Q) e baixa taxa de erro de bit (BER). / The present work aimed to investigate by means of numerical simulations, a device able to perform 3R regeneration (Re-amplifying, Re-timing and Re-shaping) fully propagated signal in an optical communication system for optical fiber with bit rate of 10 Gbit/s, the initial transmit power 0 dBm and wavelength of 1550 nm. As an ally to the regeneration process using dispersive and nonlinear effects of self-phase modulation (SPM), cross-phase modulation (XPM) and four-wave mixing (FWM) in a Mach-Zehnder Interferometer, whose one of the arms is composed of a Highly Nonlinear Photonic Crystal Fiber (HNL-PCF). The simulations were performed using OptiSystem commercial software of company canadian Optiwave Corporation. System performance was analyzed by comparing the values of the quality factor (Q-factor), of the bit error rate (BER), of optical spectrum and the optical signal-to-noise ratio (OSNR) optical signals are regenerated, before regenerated and degraded in the entrance and exit of the proposed system. Through this project, it was possible to obtain an efficient signal regeneration, with optimal values of OSNR, quality factor (Q-factor) and low bit error rate (BER).

<p>For the first time in the history of physics we stand in front of a theory that might actually serve as a unification of it all - string theory. It provides a self-consistent framework for gravity and quantum mechanics, which naturally incorporates matter and gauge interactions of the type seen in the standard model. Unfortunately, at the moment we do not know of any principle that selects the vacuum of the theory, so predictions about our four-dimensional world are still absent. However, the introduction of extended objects opens up an intricate new arena of physics, which is non-trivial and challenging to map out, even at a basic level.</p><p>A key concept of quantum gravity is holography; this is realised in string theory by the AdS/CFT correspondence, which relates string theory to a field theory living in a lower dimensional space. In this thesis we discuss two limits of the correspondence, namely the BMN limit, giving rise to a plane wave geometry, and the tensionless limit, exhibiting massless higher spin interactions. We also study a limit of string theory in a background electric field, where the theory is described by open strings and positively wound closed strings only.</p><p>We begin with a brief review of the theory, focusing on an intuitive understanding of the basic aspects and serving as an introduction to the papers. In the first paper we calculate, from two different points of view, scattering amplitudes in the non-commutative open string limit. In the second paper we obtain the quadratic scalar field contributions to the stress-energy tensor in the minimal bosonic higher spin gauge theory in four dimensions. In the last paper we propose a way to avoid fermion doubling when discretizing the string in the BMN limit.</p>

For the first time in the history of physics we stand in front of a theory that might actually serve as a unification of it all - string theory. It provides a self-consistent framework for gravity and quantum mechanics, which naturally incorporates matter and gauge interactions of the type seen in the standard model. Unfortunately, at the moment we do not know of any principle that selects the vacuum of the theory, so predictions about our four-dimensional world are still absent. However, the introduction of extended objects opens up an intricate new arena of physics, which is non-trivial and challenging to map out, even at a basic level. A key concept of quantum gravity is holography; this is realised in string theory by the AdS/CFT correspondence, which relates string theory to a field theory living in a lower dimensional space. In this thesis we discuss two limits of the correspondence, namely the BMN limit, giving rise to a plane wave geometry, and the tensionless limit, exhibiting massless higher spin interactions. We also study a limit of string theory in a background electric field, where the theory is described by open strings and positively wound closed strings only. We begin with a brief review of the theory, focusing on an intuitive understanding of the basic aspects and serving as an introduction to the papers. In the first paper we calculate, from two different points of view, scattering amplitudes in the non-commutative open string limit. In the second paper we obtain the quadratic scalar field contributions to the stress-energy tensor in the minimal bosonic higher spin gauge theory in four dimensions. In the last paper we propose a way to avoid fermion doubling when discretizing the string in the BMN limit.

The object of the thesis was to develop a simple method of the ADC quality evaluation of computer audio systems, which does not require a special apparatus, and software for its realization. To correct the ADC ENOB measurement methodology recommended in the IEEE Std 1241-2000. By applying the recommended method, to investigate possibilities of formation and application of new test analog signals for ADC investigation. To show the possibilities of untraditional computer audio systems application for measurements.

The object of the thesis was to develop a simple method of the ADC quality evaluation of computer audio systems, which does not require a special apparatus, and software for its realization. To correct the ADC ENOB measurement methodology recommended in the IEEE Std 1241-2000. By applying the recommended method, to investigate possibilities of formation and application of new test analog signals for ADC investigation. To show the possibilities of untraditional computer audio systems application for measurements.