Over the past two decades, power consumption has increased exponentially worldwide, posing new challenges to power grids to meet the load requirements. With this growing power demand, the need for efficient high-density medium-voltage (MV) power converters has increased to support flexible power distribution grids. The modular multilevel converters (MMC) became the most typical MV power converters in applications from 2010. This topology has many advantages, such as voltage scalability, excellent output performance, and low voltage ratings for switching devices. However, without the excellent reliability of the MMC, applications cannot reap these benefits. The MMC topology comprises several series-connected submodules (typically a half-bridge or a full-bridge inverter). As a result of increased switching devices, the converter becomes vulnerable since a single device fault can disrupt the whole converter operation. Therefore, fault-tolerant strategies to replace faulty SM with a redundant SM are developed using additional bypass switches. Conventionally TRIACs and vacuum switches are employed as bypass switches that operate in the range of 2-10 microseconds. Despite having performance advantages, MMCs are still not fully employed in aerospace and naval industries due to their enormous size. Many Power Electronics Building Blocks (PEBB) are proposed, with size optimization, as submodules for modular converters. The PEBB1000, a 1000 V- PEBB proposed by Dr. Jun Wang, achieved a significant size reduction of 80% with a novel switching cycle control (SCC) scheme. This novel control scheme requires high switching frequency and high di/dt-currents for MMC operation. Due to di/dt-rate limitations, TRIAC-based switch cannot perform bypass operation. Therefore, research work has been conducted on bypass switches for PEBB1000 using wide-bandgap SiC devices. This thesis presents the design of a SiC MOSFET-based bypass switch for PEBB1000 in MMC application. A detailed fault case analysis is presented to show the feasibility of the bypass operation for 90% PEBB-level faults. Significant variations in PEBB1000 bypass requirements are observed through SCC-based MMC simulations. Accordingly, a 1700 V, 100 A bypass switch has been designed using the anti-series topology of MOSFETs. Various specifications, such as 142 nanoseconds operation time, 500 nanoseconds bypass commutation time, and 277A transient current conduction capability, are validated through practical tests. Results prove that SiC-MOSFETs work better than TRIACs in high di/dt-current conduction and operation times. For future work, false-triggering endurance has to be analyzed for 1000 V switching voltage. / Master of Science / When a building is on fire, the safety of people inside depends on the timely arrival of the fire rescue departments. Similarly, for an electrical fault, the safety of electrical systems depends on fast and secure fault protection devices. This thesis presents work on one such fault-protection device used in the power distribution grid: solid-state bypass switch. Distribution grids supply power majorly to households and industries at the city or state level. They employ medium-voltage (MV) converters to step down the voltages to meet the distribution requirements. In MV converters, several low-voltage modules are connected in series to achieve the high-voltage power conversion. When a fault occurs at one of the low-voltage modules in MV converters, power flow gets disrupted due to a series connection like a chain. Therefore, bypass switches are connected in parallel to low-voltage modules for an alternate power flow path. Conventionally used bypass switches have 2-10 microseconds operation time. Recent advancements in semiconductor devices, SiC MOSFETs, allow operation times less than one microsecond. Therefore, research work has been conducted on bypass switches using SiC MOSFETs. Finally, the SiC-MOSFET based bypass switch is built and tested according to converter requirements. Results proved that the designed switch operates in 142 nanoseconds, ten times faster than a conventional switch.

Electronic design automation (EDA) tools play a central role in bridging the productivity gap for designing complex hardware systems. However, with an increase in the size and complexity of today's design requirements, current methodologies and EDA tools are unable to effectively mitigate the further widening of productivity gap. It is estimated that testing and verification takes 2/3rd of the total development time of complex hardware systems. Functional simulation forms the main stay of testing and verification process and is the most widely used technique for testing and verification. Most of the simulation algorithms and their implementations are designed for uniprocessor systems that cannot easily leverage the parallelism in multi-core and GPU platforms. For example, logic simulation often uses levelized sequential algorithms, whereas the discrete-event simulation frameworks for Verilog, VHDL and SystemC employ concurrency in the form of multi-threading to given an illusion of the inherent parallelism present in circuits. However, the discrete-event model of computation requires a global notion of an event-queue, which makes improving its simulation performance via parallelization even more challenging. This work investigates automatic parallelization of simulation algorithms used to simulate hardware models. In particular, we focus on parallelizing the simulation of hardware designs described at the RTL using SystemC/HDL with examples to clearly describe the parallelization. Even though multi-cores and GPUs other parallelism, efficiently exploiting this parallelism with their programming models is not straightforward. To overcome this, we also focus our research on building intelligent translators to map simulation applications onto multi-cores and GPUs such that the complexity of the low-level programming models is hidden from the designers. / Master of Science

Nature has always remained a constant source of inspiration for chemists for synthesizing natural products, mimicking enzymatic reactions or to construct molecular architectures resembling biological assemblies. With the rapid growth of ‘Supramolecular Chemistry’ along with the advancement of the synthetic methodologies, molecular systems with brand new complexities have been synthesized, alongside the efficacy of weak, reversible non-covalent interactions have also been extensively explored. A number of such forces including hydrogen bonding, solvophobic effect, dynamic covalent interactions and metal-ligand coordination have been exploited to assemble the molecular building blocks and stitch them together to construct discrete ‘self-assembled’ architectures integrated with desired functionalities. Metal-ligand coordination driven self-assembly certainly evolved as one of the most successful approaches for the construction of discrete supramolecular architectures during last two and half decades. The high directionality and reversible nature of certain metal-ligand bonds allow the pre-designing of sophisticated architectures which can be successfully obtained by ‘error corrections’ via a thermodynamically controlled self-assembly process. Numerous aesthetically elegant two dimensional (2D) and three dimensional (3D) metallosupramolecular architectures have been constructed which have been studied for various potential applications including guest encapsulation, catalysis, sensing, optoelectronics, drug delivery, protection of reactive species etc. Construction of such molecular architectures uses symmetric and rigid building blocks which strictly preserves their geometrical coding and thus finally determines the fate of the self-assembly. Pyridyl-based donors have been extensively used due to their well-behaved coordination with transition metal ions. Interestingly, imidazole based donors remained almost unexplored for such purpose mainly due to the rotational flexibility of imidazole moieties owing to the lack of -electron delocalization with the aromatic backbone, which makes pre-designing an architecture extremely difficult. However, this unpredictability can lead to the formation of unprecedented molecular architectures. Furthermore, the conventional rigid ‘acceptors’ used in the ‘directional bonding approach’ always results in the formation of rigid assemblies, which cannot be utilized for the construction of smart molecular machine based applications. In this context, incorporation of restricted rigidity in the building blocks can be a convenient approach to construct versatile and flexible supramolecular architectures. Although flexible donors are quite common in coordination-driven self-assembly, the use of flexible metal acceptor is scarcely Highly symmetric spherical assemblies of square planer Pd(II) and Pt(II) ions are one of the most extensively studied metallosupramolecular architectures owing to their topological similarity with the spherical virus capsids. Unfortunately, none of the reported molecular spheres are soluble in water which restricts their applications in aqueous media. On the other hand, most of the metallosupramolecular architectures cannot be used for redox based applications as the oxidation state of the associated metal ions must be kept unaltered. Although, assemblies constructed mainly by the ferrocene containing acceptors are shown to be exhibiting redox property, the donor inherited redox active metallosupramolecular systems are extremely rare. Discrete 3D metallosupramolecular cages have been extensively studied as synthetic hosts where the hydrophobic pockets have been utilized as safe shelter for reactive species, for catalyzing chemical transformations, tuning electronic and optical properties of guest molecules, as delivery vehicle for drug molecules etc. However, a major drawback of many such 3D cages is associated with their closed-shell topology, where the large cavities are accessible though relatively much smaller apertures which prevent larger guest molecules to enter inside. So, an interesting finding in this field would be to construct molecular hosts with larger apertures. Picric acid (PA) is a strong organic acid and like many other polynitroaromatic compounds, it is a powerful explosive. In addition, it has large scale industrial application for the synthesis of dyes and pharmaceuticals. However, PA has potential health hazards and it is a water pollutant owing to its high aqueous solubility. Thus, the development of selective receptors which can efficiently interact with PA and detect it at very lower concentration is an appealing field of research. Chapter 1 briefly discusses the history of supramolecular chemistry and the concept of ‘self-assembly’ along with the several synthetic methodologies for the construction of discrete supramolecular architectures. It also includes a brief discussion on the various design approaches to construct 2D and 3D molecular architectures by metal-ligand coordination which is followed by an account on some of the important applications of such metallosupramolecular architectures. At the end, a small introduction on the fluorescence-based detection techniques for PA has also been included. Chapter 2A accounts for the exploration of two linearly substituted benzene bisimidazole donors L1 and L2 for coordination-driven self-assembly. L1 and L2 possesses different ‘natural’ donor angles as the imidazole moieties in L2 are twisted heavily with respect to the phenyl plane due to the steric hindrance exerted by the methyl groups. Interestingly, while the self-assembly of L1 with [cis-(tmeda)Pd(NO3)2] (tmeda = N,N,Nꞌ,Nꞌ-tetramethylethane-1,2-diamine) exclusively formed a [3+3] molecular triangle, the self-assembly of L2 yielded a [4+4] molecular square as the major product with the same acceptor. In addition, similar treatment with the analogous Pt(II) acceptor resulted mixtures of [3+3] and [4+4] assemblies in both cases; however, the [3+3] assembly was the major product in case of L2. These contradictory product distributions in case of L2 with analogous Pd(II) and Pt(II) acceptors could be corroborated by the delicate balance between the entropic and enthalpic contributions. Scheme 1. Self-assembly of L1/L2 with [cis-(tmeda)Pd(NO3)2] and [cis-(tmeda)Pt(NO3)2], respectively. Furthermore, the reactions of L1 and L2 with a 0º bisplatinum acceptor, viz. AntPt yielded the expected [2+2] macrocycles (8 and 9), respectively. However, the interesting observations Scheme 2. Self-assemblies of L1 and L2 with the 0º bisplatinum acceptor AntPt. obtained from the variable temperature NMR studies suggested the existence of a mixture of inter-convertible conformational isomeric structures of 9. Chapter 2B describes the synthesis of a novel semi-rigid bisplatinum acceptor bisPt-NO3 based on benzil backbone for the construction of flexible metallamacrocycles. The benzil group was selected due to its unique rotational flexibility along the benzyl C-C bond which can generate a wide range of bite angles to make it compatible with the variety of donors of diverse shapes and sizes. The acceptor was successfully self-assembled with four different bisimidazole donors (L1-L4) to yield corresponding [2+2] metallamacrocycles (M1-M4) which were characterized by multinuclear NMR and ESI-MS spectrometry; and their structures were elucidated by semi-empirical geometry optimizations. Scheme 3. Self-assembly of [2+2] metallamacrocycles M1-M4 by a semi-rigid bisplatinum acceptor bisPt-NO3. Chapter 3 discusses the synthesis of the very first example of a water soluble molecular sphere MC-1 by the self-assembly of square planar Pd(II) ions with a flexible cationic tritopic donor La(NO3)3 containing 4,4-bispyridyl arms. The structural flexibility of La(NO3)3 makes it capable of binding with metal ions in its syn- or anti-conformations which was also experimentally observed in the structures of the three newly synthesized coordination polymers, viz. Ag-CP, Zn-CP and Cd-CP constructed by using La(NO3)3 as (co)ligand. Finally, the 4:3 self-assembly of [La(NO3)3] and Pd(NO3)2 in aqueous media produced the desired M6L8 type Scheme 4. Self-assembly of the water soluble molecular dice MC-1 from the tricationic tritopic donor La(NO3)3. molecular sphere- MC-1, which contain 36+ overall charges. The compound could be easily solubilized in water after isolation as solid by simple stirring at room temperature. Single crystal X-ray diffraction analysis (SCXRD) revealed the ‘dice’-shaped architecture of MC-1 where the eight faces are occupied by the coordinated Pd2+ ions and the bispyridyl arms and the vertices are occupied by mesityl moieties. MC-1 is stable in aqueous media, however disintegrates in DMSO, as observed by variable temperature NMR experiments. In addition, MC-1 also produced ligand inherited redox signals in cyclic voltammetry experiments. Chapter 4 describes the synthesis of a novel non-symmetric tetraimidazole donor L based on carbazole backbone. The complexity of the donor is associated with the allowed free rotation of the imidazole moieties along with the non-symmetric nature of the carbazole backbone which make L a very unusual donor for coordination-driven self-assembly. The crystal structure of L showed that the presence of the N-Me group caused a greater twisting of the nearby imidazole moieties with respect to the other set of imidazole moieties. The self-assembly of L with [cis-(en)Pd(NO3)2] (en = ethane-1,2-diamine) yielded a mixture of M4L8 and M6L12 type self-assembled products, as evidenced from the ESI-MS spectrometry. However, the DOSY NMR spectra of the product showed a single diffusion coefficient for all the peaks, indicating that both type of assemblies have similar size and hence suggested the formation of a tetrafacial barrel and a cubic architecture. A similar self-assembly of L with [cis-(tmeda)Pd(NO3)2] also produced a water soluble product. ESI-MS spectra in this case only confirmed the formation of a M4L8 assembly- MB-1. SCXRD analysis of the coronene encapsulated complex of MB-1 gave more insights on the sophisticated non-symmetric tetrafacial barrel architecture of MB-1 with large Scheme 5. Construction of the water soluble molecular barrel MB-1 by the self-assembly of a non-symmetric tetraimidazole donor L. rectangular apertures. The centrosymmetric molecule can encapsulate two aromatic guest molecules inside its hydrophobic cavity and was found to be efficiently encapsulating polyaromatic hydrocarbons (PAHs) in aqueous media. In addition, MB-1 has been successfully exploited to carry water insoluble perylene molecule inside HeLa cells for fluorescence imaging purpose without showing significant toxicity. L also formed a water insoluble tetrafacial barrel (MB-2) by self-assembly with [cis-(dppf)Pd(OTf)] (dppf=diphenylphosphino ferrocene) which interestingly has a symmetrical architecture, as evidenced from the SCXRD analysis. The formation of the symmetrical barrel is driven by the steric hindrance between the bulky phenyl groups of the nearby dppf moieties. Chapter 5 reports the study of interactions between picric acid (PA) with a few newly synthesized fluorescent imidazolium salts (S1-S3). The fluorescence titration study of the positively charged receptors with PA showed rapid decrease of the corresponding fluorescence intensities upon gradual addition of PA. The Stern-Volmer plots suggested the involvement of both static and dynamic quenching mechanisms which was further supported by fluorescence lifetime measurements, NMR and UV-Vis spectroscopic analyses. The values of the Stern-Volmer constants (Ksv) reflected strong receptor-PA binding. The quenching efficiency calculations in the presence of several other analytes proved that the receptors are highly selective for PA in both aqueous and non-aqueous media. The mode of interactions in solid state was investigated by the crystal structure analysis of the [S1PA] complex. 1H NMR spectra of the same complex indicated strong interaction between the imidazolium moieties of the receptor Scheme 6. The fluorescent imidazolium salts based receptors S1-S3 and the florescence titration plot for S1 with PA. Inset: the solutions of S1 and (S1+PA) in DMSO under UV light. with PA in solution; however, no significant interaction of PA with the anthracene moieties was observed in solution as we well as in the solid state. Also the quenching efficiencies and the Ksv values were correlated with the positive charge(s) present on the receptors with the help of two newly synthesized mono-positive receptors S4 and S5.

Syftet med denna undersökning är att undersöka hur undervisningen om partikelmodellen bedrivs i årskurserna 4–6 och hur undervisningen utformas. Studien genomfördes med hjälp av kvalitativt inriktade intervjuer med fem olika lärare som undervisar inom No-ämnena i de aktuella årskurserna. Resultatet visar att alla fem lärarna undervisar om fasövergångar och materians byggstenar, men att lärarna fördjupar sig inom olika delar av dessa områden.  Lärarna i undersökningen väljer olika undervisningsmetoder när de undervisar om partikelmodellen: Traditionell undervisning, hypoteser, datoranimeringar, laborationer, dramatiseringar och användning av konkret material. / The purpose with this paper has been to examine how the education about the particle model in grades 4–6 is conducted and how the education is carried out. The study was carried out with the help of qualitatively directed interviews with five teachers that teach in the science subjects in the grades in question. The results show that all five teachers teach about, phase transitions and the building blocks of matter, but choose to immerse in different parts of these subjects. The teachers choose different teaching methods to teach about the particle model: Traditional teaching, hypotheses, computer animations, laboratory, dramatization and use of concrete materials.

Depuis le début des années 1990, la chimie combinatoire dynamique a proposé une stratégie efficace pour la conception de nouveaux récepteurs spécifiques. En utilisant cette approche pour la reconnaissance de modifications post-traductionnelles de protéines, nous avons pu identifier par sérendipité puis isolé deux récepteurs potentiels d’acides aminés aromatiques, sensibles à la polarité du résidu le plus proche. Basés sur les conclusions de cette première étude, nous avons développé une nouvelle famille moléculaire d’analogues dynamiques polyfonctionnels des pillararènes : les dynarènes. Après avoir développé les voies de synthèse menant à l’obtention des briques constitutives, les premières études en chimie combinatoire dynamique nous ont permit de valider l’utilisation de ces briques pour la création de récepteurs multivalents, possédant une taille de la cavité ou de la couronne fonctionnelle optimale. En développant des synthèses efficaces à l‘échelle du gramme de ces nouveaux récepteurs moléculaires, nous avons enfin pu étudier la dynamique conformationnelle des objets. / Since the nineties, Dynamic Combinatorial Chemistry (DCC) has proven to be an efficient approach to design receptors capable of specific molecular recognition. Using this strategy for protein post-translational modification recognition, we serendipitously identified then isolated two potential aminoacids receptors, which are sensitive to the polarity of the nearest neighbor. On the basis of this preliminary study, we developed a new molecular family of multifunctional dynamic pillararene-like: the dynarenes. After the development of new synthetic routes to obtain constitutive building blocks, first studies in DCC allowed us to validate the use of such building blocks for multivalent receptor design, with optimized size and function. By developing efficient gramme-scale syntheses of new receptors, we study the conformational dynamics of the new compounds.

The modular nature of metal−organic materials allows for tuning their properties to meet a specific application through careful design of the molecular precursors, i.e. information encoding at the molecular level. Research in this area is highly interdisciplinary where synthetic organic chemistry, in silico modeling, and various analytical techniques merge together to afford better understanding of the basic science involved and eventually to result in enhanced control over the properties of targeted materials.

Este trabalho estuda os efeitos de dose total ionizante (TID – Total Ionizing Dose) em amplificadores operacionais e em seus blocos básicos de construção. A radiação ionizante presente no espaço pode afetar o funcionamento das estruturas MOS, sendo que um dos parâmetros mais prejudicados é a tensão de limiar (Threshold Voltage). Em virtude da diferença nos mecanismos de aprisionamento de cargas nos óxidos dos transistores do tipo N e do tipo P, esses dois dispositivos exibem comportamentos distintos à medida que a dose acumulada aumenta referente à tensão de limiar. Por isso, foram investigados os comportamentos de dois tipos de amplificadores que podem ser ditos complementares entre si. Nesse contexto, através de simulações SPICE desvios na tensão de limiar foram promovidos através da injeção direta no arquivo de parâmetros da tecnologia considerada. Com isso, um conjunto de simulações foi feito para gerar a estimativa da tendência de comportamento de parâmetros que qualificam o desempenho dos amplificadores operacionais, como é o caso do produto ganho largura de banda (GB), ganho DC e THD (Total Harmonic Distortion). Nesse sentido, foi possível compreender os mecanismos associados à degradação de desempenho e concluir qual das duas arquiteturas pode apresentar melhor desempenho relacionado à TID. / This work studies the effects of Total Ionizing Dose (TID) in operational amplifiers as well as in their basics building blocks. The radiation from space may affect functionality of MOS structures. One the most affected parameters is the threshold voltage. Due to the difference between N-type and P-type transistors related to the mechanism of charge trapping into the oxides, these two devices exhibit different behaviors, related to the threshold voltage parameter according to accumulated dose. Therefore, this work investigates the behavior of two counterpart operational amplifiers. In this context, by means of SPICE simulations, threshold deviations are injected into the transistors by modifying the technology models of the devices. Thus, a set of simulations was performed in order to generate an estimative of tendency for some of performance parameters of operational amplifiers, such as: the gain-bandwidth product (GB), DC gain, THD (Total Harmonic Distortion). In this sense, it was possible to understand the mechanisms associated to performance degradation and also, to conclude which of both architectures is more robust related to TID.

Este trabalho estuda os efeitos de dose total ionizante (TID – Total Ionizing Dose) em amplificadores operacionais e em seus blocos básicos de construção. A radiação ionizante presente no espaço pode afetar o funcionamento das estruturas MOS, sendo que um dos parâmetros mais prejudicados é a tensão de limiar (Threshold Voltage). Em virtude da diferença nos mecanismos de aprisionamento de cargas nos óxidos dos transistores do tipo N e do tipo P, esses dois dispositivos exibem comportamentos distintos à medida que a dose acumulada aumenta referente à tensão de limiar. Por isso, foram investigados os comportamentos de dois tipos de amplificadores que podem ser ditos complementares entre si. Nesse contexto, através de simulações SPICE desvios na tensão de limiar foram promovidos através da injeção direta no arquivo de parâmetros da tecnologia considerada. Com isso, um conjunto de simulações foi feito para gerar a estimativa da tendência de comportamento de parâmetros que qualificam o desempenho dos amplificadores operacionais, como é o caso do produto ganho largura de banda (GB), ganho DC e THD (Total Harmonic Distortion). Nesse sentido, foi possível compreender os mecanismos associados à degradação de desempenho e concluir qual das duas arquiteturas pode apresentar melhor desempenho relacionado à TID. / This work studies the effects of Total Ionizing Dose (TID) in operational amplifiers as well as in their basics building blocks. The radiation from space may affect functionality of MOS structures. One the most affected parameters is the threshold voltage. Due to the difference between N-type and P-type transistors related to the mechanism of charge trapping into the oxides, these two devices exhibit different behaviors, related to the threshold voltage parameter according to accumulated dose. Therefore, this work investigates the behavior of two counterpart operational amplifiers. In this context, by means of SPICE simulations, threshold deviations are injected into the transistors by modifying the technology models of the devices. Thus, a set of simulations was performed in order to generate an estimative of tendency for some of performance parameters of operational amplifiers, such as: the gain-bandwidth product (GB), DC gain, THD (Total Harmonic Distortion). In this sense, it was possible to understand the mechanisms associated to performance degradation and also, to conclude which of both architectures is more robust related to TID.

Este trabalho estuda os efeitos de dose total ionizante (TID – Total Ionizing Dose) em amplificadores operacionais e em seus blocos básicos de construção. A radiação ionizante presente no espaço pode afetar o funcionamento das estruturas MOS, sendo que um dos parâmetros mais prejudicados é a tensão de limiar (Threshold Voltage). Em virtude da diferença nos mecanismos de aprisionamento de cargas nos óxidos dos transistores do tipo N e do tipo P, esses dois dispositivos exibem comportamentos distintos à medida que a dose acumulada aumenta referente à tensão de limiar. Por isso, foram investigados os comportamentos de dois tipos de amplificadores que podem ser ditos complementares entre si. Nesse contexto, através de simulações SPICE desvios na tensão de limiar foram promovidos através da injeção direta no arquivo de parâmetros da tecnologia considerada. Com isso, um conjunto de simulações foi feito para gerar a estimativa da tendência de comportamento de parâmetros que qualificam o desempenho dos amplificadores operacionais, como é o caso do produto ganho largura de banda (GB), ganho DC e THD (Total Harmonic Distortion). Nesse sentido, foi possível compreender os mecanismos associados à degradação de desempenho e concluir qual das duas arquiteturas pode apresentar melhor desempenho relacionado à TID. / This work studies the effects of Total Ionizing Dose (TID) in operational amplifiers as well as in their basics building blocks. The radiation from space may affect functionality of MOS structures. One the most affected parameters is the threshold voltage. Due to the difference between N-type and P-type transistors related to the mechanism of charge trapping into the oxides, these two devices exhibit different behaviors, related to the threshold voltage parameter according to accumulated dose. Therefore, this work investigates the behavior of two counterpart operational amplifiers. In this context, by means of SPICE simulations, threshold deviations are injected into the transistors by modifying the technology models of the devices. Thus, a set of simulations was performed in order to generate an estimative of tendency for some of performance parameters of operational amplifiers, such as: the gain-bandwidth product (GB), DC gain, THD (Total Harmonic Distortion). In this sense, it was possible to understand the mechanisms associated to performance degradation and also, to conclude which of both architectures is more robust related to TID.

Dans un contexte du développement durable, la bioproduction de synthons (molécules plateformes, ou building blocks) de façon biosourcée à partir de biomasse végétale, constitue une voie de remplacement des actuelles molécules prétrosourcées. Ce travail de thèse concerne spécifiquement l’utilisation de la biomasse lignocellulosique, renouvelable et abondante, pour la production de deux acides organiques d’intérêt : l’acide itaconique et l’acide fumarique. Ces molécules ont été choisies notamment car elles peuvent générer des polymères aux propriétés intéressantes. Les travaux expérimentaux ont consisté à utiliser le son de blé et les rafles de maïs, déchets agricoles, comme substrats pour la fermentation de quatre souches de champignons filamenteux du genre Aspergillus. Des criblages des meilleures conditions fermentaires montrent que les rafles de maïs permettent d’atteindre des rendements plus élevés, surtout en fermentation en milieu solide. Parmi d’autres résultats marquants, nous avons montré pour la première fois la capacité d’Aspergillus oryzae à produire l’acide itaconique. L’ensemble de nos résultats montrent que l’utilisation de la biomasse lignocellulosique est une alternative prometteuse pour la production de ces deux synthons d’intérêt industriel. / In the context of sustainable development, the bioproduction of building blocks (chemical platforms) from biomass is way to substitute the current fossil-based chemical molecules. This thesis is focused on the use of lignocellulosic biomass, renewable and abundant, towards the production of two organic acids (potential building blocks): itaconic acid and fumaric acid. These molecules have been chosen especially because they can generated polymers with interesting properties. The experimental work consisted in using wheat bran and corn cobs, agricultural wastes, as substrates for fermentation by four strains of filamentous fungi from Aspergillus genus. Screenings of the best fermentation conditions show that enzymatically pretreated corn cobs, especially in solid state fermentation achieve higher yields, especially in solid state fermentation. Among other notable results, we have shown for the first time the ability of Aspergillus oryzae to produce itaconic acid. Overall, our results show that the use of lignocellulosic biomass is a promising alternative for the production of these two building blocks of industrial interest.