Modular Multilevel Converters (MMC) are being widely considered for medium to high voltage DC generation systems. Integrated system design optimization of the generator-MMC system through multi-objective optimization is of interest, because such an approach allows the trade-off between competing objectives (for example, mass and loss) to be explicitly and quantitatively identified. In this work, such an optimization based design paradigm for MMC based generator rectifier systems is developed. To formulate the design problem as a multi-objective optimization problem, it is required that the system waveforms can be obtained to facilitate the imposition of constraints and the estimation of power losses. Similarly, it is also desired to include detailed electric machine magnetic and electrical analysis in design optimization, as well as aspects such as the inductor and heat sink design. Such development typically requires detailed component design and simulation models for the electric machine and converter which are computationally expensive. As an alternative, the proposed work utilizes an electric machine metamodel, heat sink metamodel, and high-speed steady-state simulation model for the MMC to facilitate multi-objective optimization minimizing system metrics of interest while satisfying system constraints. Using the developed component simulation and design models, a multi-objective optimization based design of an MMC based generator-rectifier system is conducted.

The logistics department at the Powertrain plant of Volvo Trucks seeks to improve the efficiency within their processes. A new concept solution to the supports (pallets) that hold and carry different types of engine parts during the transportation between the sequencing area and the final assembly line called “The new dynamic pallet based on biomimicry” was presented. The concept solves the issues of the constant modifications in the pallets lead by the changes in the design of the engine parts. The main objectives of the project is the creation of a dynamic pallet, dynamic in this case translates into a modular, flexible to different geometries and scalable system, also the design solution should be inspired by nature (biomimicry) to boost a new sustainable design approach related to the values of Volvo brand. This project required iterative research regarding the principles of biomimicry and systems found in nature. Biomimicry literally means ‘the imitation of life’ but, it is better defined as a design approach to innovation which takes inspiration from systems of nature. It is provided by Volvo as the core of the project, if the result is good then there will be a push to develop new projects following this strategy seeking sustainable solutions to solve human problems. In addition, prototyping concepts from a generation of ideas to testing results were conducted to evaluate the concepts generated. The resulting concept proposal is a whole new system but preserves the functional aspects necessary to integrate the new pallet in the current logistics performance.

In this thesis we investigate the role of odd Poisson brackets in related areas of supergeometry. In particular we study three different cases of their appearance: Courant algebroids and their homotopy analogues, weak Poisson structures and their relation to foliated manifolds, and the structure of odd Poisson manifolds and their modular class. In chapter 2 we introduce the notion of a homotopy Courant algebroid, a subclass of which is suggested to stand as the double objects to L-bialgebroids. We provide explicit formula for the higher homotopy Dorfman brackets introduced in this case, and the higher relations between these and the anchor maps. The homotopy Loday structure is investigated, and we begin a discussion of what other constructions in the theory of Courant algebroids can be carried out in this homotopy setting. Chapter 3 is devoted to lifting a weak Poisson structure corresponding to a local foliation of a submanifold to a weak Koszul bracket, and interpreting the results in terms of the cohomology of an associated differential. This bracket is shown to produce a bracket on co-exact differential forms. In chapter 5 studies classes of second order differential operators acting on semidensities on an arbitrary supermanifold. In particular, when the supermanifold is odd Poisson, we given an explicit description of the modular class of the odd Poisson manifold, and provide the first non-trivial examples of such a class. We also introduce the potential field of a general odd Laplacian, and discuss its relation to the geometry of the odd Poisson manifold and its status as a connection-like object.

O Ferro Fundido Nodular Austemperado (ADI) vem despertando interesse no mercado por seu menor custo de fabricação e por seu elevado potencial de substituir, principalmente, o aço em peças que demandem por alta resistência mecânica e resistência ao desgaste. Esses fatores o convertem num material de engenharia cada vez mais utilizado, impondo-se em campos até então reservados a outras ligas e métodos de conformação. O tratamento térmico de austêmpera fornece uma microestrutura única, constituída de ferrita acicular e austenita estável rica em carbono, mais frequentemente denominada de ausferrita. Assim, o ADI oferece uma boa relação resistência/peso e uma boa combinação de resistências mecânicas. Contudo, a usinagem do ADI quando comparado com os outros ferros fundidos, apresenta um grande desafio. Dentro desse cenário, esse trabalho visa analisar as possibilidades e os métodos para tornar a sua usinagem mais rentável. O objetivo deste estudo foi o torneamento de alguns tipos de ADI, com o intuito de se verificar, em termos de usinagem, a viabilidade técnica e econômica do seu uso. Para tanto, em primeiro lugar realizou-se uma caracterização detalhada do material e em seguida foram realizados ensaios de vida de ferramenta variando-se parâmetros e ferramentas de corte. Também foram realizados ensaios para medição das forças de corte e análise dos cavacos, incluindo ensaios de quick-stop. Foram analisadas algumas características tribológicas do material através de um ensaio pino-sobre-disco e por ensaios de usinagem para medição da rugosidade. Os resultados desta pesquisa apontam algumas melhorias para o desenvolvimento de novos gumes, baseado nos mecanismos de desgaste encontrados. Verificou-se a presença do desgaste por lascamento do gume em vários ensaios, bem como os mecanismos de abrasão e de adesão. Diferindo-se dos ferros fundidos tradicionais, o cavaco é do tipo contínuo e o maior tempo de contato deste com a superfície de saída da ferramenta é decisivo no comportamento das ferramentas de metal duro. A ferramenta de metal duro microgrão da classe P10 obteve o melhor desempenho na usinagem do ADI, tanto em condições de desbaste quanto de acabamento.

O gás natural é uma fonte alternativa ao petróleo. É uma fonte de energia considerada mais limpa e segura dentre as fontes de energias não renováveis e, por isso, vem aumentando sua participação na matriz energética. Deste modo, impulsionou a criação e ampliação de diversas malhas de gasodutos. O objetivo do presente trabalho é simular redes de gasodutos utilizando ferramentas computacionais disponíveis no mercado. O HYSYS® foi adequado para simular longos gasodutos lineares. Portanto, a estratégia sequencial modular foi adequada para estas configurações. Contudo, não apresentaram bons resultados para redes. O software gratuito iiSE apresenta bons resultados para redes complexas, comprovando que os softwares orientados a equações são mais apropriados para sistemas com paralelismo. / Natural gas is an alternative source for oil. It is an energy source considered more clean and safe among the non-renewable energy sources and, therefore, its participation is increasing in the energy matrix. In this way, spurred the creation and expansion of several meshes of pipelines. The objective of this study is to simulate gas pipeline networks using computational tools available on the market. The HYSYS ® was suitable to simulate long linear gas pipelines. Therefore, the sequential modular strategy was appropriate for these settings. However, did not provide good results for networks. The free software iiSE presents good results for complex networks, proving that the software orixented to equations are more suitable for systems with parallelism.

Neste trabalho, por meio de uma metodologia experimental foram analisados vários aspectos de tijolos modulares compostos por misturas binárias e ternárias de solo-cimento e solo cimento-sílica produzidos em prensa manual modelo SAHARA, com a finalidade de se obter parâmetros e diretrizes que visam um melhor desempenho do material. Realizaram-se ensaios em corpos-de-prova cilíndricos de maneira acessória no decorrer do trabalho, o que resultou no suporte para fundamentação de diversas avaliações sobre as composições de traços utilizados na fabricação dos tijolos. Foram executados painéis de parede com o objetivo de verificar o comportamento da alvenaria em relação à resistência à compressão e à deformabilidade das paredes, possibilitando correlações com os resultados dos ensaios de prismas, tijolos e argamassa de assentamento. As contribuições da pesquisa permitem relacionar a tecnologia da fabricação de tijolos de solo-cimento com o contexto de construção sustentável e o aproveitamento de resíduos industriais, além de sistematizar informações para a elaboração de um projeto tecnológico com os tijolos modulares / In this work, several aspects of modular bricks composed by binary and ternary mixtures of soil-cement and soil-cement-silica, produced by manual press model SAHARA, were analyzed by means of an experimental methodology, with the purpose of obtaining parameters and guidelines to aim a better performance of the material. During the work, tests in cylindrical samples were executed in an accessory way, what resulted in the support for theoretical basement of several evaluations about the compositions of proportions used in brick's production. Wall panels were constructed with the objective of verifying the masonry’s behavior in relation to the compressive strength and wall’s strain, promoting correlation with the test’s results in prisms, bricks and mortar. The research’s contributions allow to relate the technology of the production of soil-cement bricks with the context of sustainable construction and the use of industrial residues in the production of construction materials, besides systematizing information for the elaboration of a technological project with the modular bricks

"It is widely recognized that security issues will play a crucial role in the majority of future computer and communication systems. A central tool for achieving system security are cryptographic algorithms. For performance as well as for physical security reasons, it is often advantageous to realize cryptographic algorithms in hardware. In order to overcome the well-known drawback of reduced flexibility that is associated with traditional ASIC solutions, this contribution proposes arithmetic architectures which are optimized for modern field programmable gate arrays (FPGAs). The proposed architectures perform modular exponentiation with very long integers. This operation is at the heart of many practical public-key algorithms such as RSA and discrete logarithm schemes. We combine two versions of Montgomery modular multiplication algorithm with new systolic array designs which are well suited for FPGA realizations. The first one is based on a radix of two and is capable of processing a variable number of bits per array cell leading to a low cost design. The second design uses a radix of sixteen, resulting in a speed-up of a factor three at the cost of more used resources. The designs are flexible, allowing any choice of operand and modulus. Unlike previous approaches, we systematically implement and compare several versions of our new architecture for different bit lengths. We provide absolute area and timing measures for each architecture on Xilinx XC4000 series FPGAs. As a first practical result we show that it is possible to implement modular exponentiation at secure bit lengths on a single commercially available FPGA. Secondly we present faster processing times than previously reported. The Diffie-Hellman key exchange scheme with a modulus of 1024 bits and an exponent of 160 bits is computed in 1.9 ms. Our fastest design computes a 1024 bit RSA decryption in 3.1 ms when the Chinese remainder theorem is applied. These times are more than ten times faster than any reported software implementation. They also outperform most of the hardware-implementations presented in technical literature."

Several algorithms for Public Key Cryptography (PKC), such as RSA, Diffie-Hellman, and Elliptic Curve Cryptography, require modular multiplication of very large operands (sizes from 160 to 4096 bits) as their core arithmetic operation. To perform this operation reasonably fast, general purpose processors are not always the best choice. This is why specialized hardware, in the form of cryptographic co-processors, become more attractive. Based upon the analysis of recent publications on hardware design for modular multiplication, this M.S. thesis presents a new architecture that is scalable with respect to word size and pipelining depth. To our knowledge, this is the first time a word based algorithm for Montgomery's method is realized using high-radix bit-parallel multipliers working with two different types of finite fields (unified architecture for GF(p) and GF(2n)). Previous approaches have relied mostly on bit serial multiplication in combination with massive pipelining, or Radix-8 multiplication with the limitation to a single type of finite field. Our approach is centered around the notion that the optimal delay in bit-parallel multipliers grows with logarithmic complexity with respect to the operand size n, O(log3/2 n), while the delay of bit serial implementations grows with linear complexity O(n). Our design has been implemented in VHDL, simulated and synthesized in 0.5μ CMOS technology. The synthesized net list has been verified in back-annotated timing simulations and analyzed in terms of performance and area consumption.

The interaction of radiation with integrated circuits can provoke transient faults due to the deposit of charge in sensitive nodes of transistors. Because of the decrease the size in the process technology, charge sharing between transistors placed close to each other has been more and more observed. This phenomenon can lead to multiple transient faults. Therefore, it is important to analyze the effect of multiple transient faults in integrated circuits and investigate mitigation techniques able to cope with multiple faults. This work investigates the effect known as single-event-induced charge sharing in integrated circuits. Two main techniques are analyzed to cope with this effect. First, a placement constraint methodology is proposed. This technique uses placement constraints in standard cell based circuits. The objective is to achieve a layout for which the Soft-Error Rate (SER) due charge shared at adjacent cell is reduced. A set of fault injection was performed and the results show that the SER can be minimized due to single-event-induced charge sharing in according to the layout structure. Results show that by using placement constraint, it is possible to reduce the error rate from 12.85% to 10.63% due double faults. Second, Triple Modular Redundancy (TMR) schemes with different levels of granularities limited by majority voters are analyzed under multiple faults. The TMR versions are implemented using a standard design flow based on a traditional commercial standard cell library. An extensive fault injection campaign is then performed in order to verify the softerror rate due to single-event-induced charge sharing in multiple nodes. Results show that the proposed methodology becomes crucial to find the best trade-off in area, performance and soft-error rate when TMR designs are considered under multiple upsets. Results have been evaluated in a case-study circuit Advanced Encryption Standard (AES), synthesized to 90nm Application Specific Integrated Circuit (ASIC) library, and they show that combining the two techniques, the error rate resulted from multiple faults can be minimized or masked. By using TMR with different granularities and placement constraint methodology, it is possible to reduce the error rate from 11.06% to 0.00% for double faults. A detailed study of triple, four and five multiple faults combining both techniques are also described. We also tested the TMR with different granularities in SRAM-based FPGA platform. Results show that the versions with a fine grain scheme (FGTMR) were more effectiveness in masking multiple faults, similarly to results observed in the ASICs. In summary, the main contribution of this master thesis is the investigation of charge sharing effects in ASICs and the use of a combination of techniques based on TMR redundancy and placement to improve the tolerance under multiple faults.

Thesis. 1975. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / M.Arch.A.S.