<p>In the past 10 years, the bandwidths and processing capabilities of the networks have increased dramatically. The number of real-time applications using these networks has also increased. The large number of real-time packets might, in a switched multi-hop network, lead to unpredictable traffic patterns. This is not a problem when the traffic intensity is low, but if the same network is used by a large number of users simultaneously, the overall performance of the network degrades. In fact, unpredictable delays in the delivery of the message can adversely affect the execution of the tasks dependent on these messages, even if we take into account the soft real-time performance.</p><p>In this paper, we investigate the effect of traffic shapers on soft real-time performance. We will consider a switched multi-hop network with FCFS queues. We will implement two versions of the network simulator. One version will be without traffic shaper and the other version will use a traffic shaper. By comparing the results (for average delay, deadline miss ratio etc.) from both the versions, we will try to conclude if it is really beneficial to use traffic shapers for soft real-time performance. Leaky bucket and token bucket algorithms are the most popular ones for traffic shaper implementation. We will consider leaky bucket algorithm for our analysis. We analyse different versions of the leaky bucket and present the trade-off’s involved.</p>

In the past 10 years, the bandwidths and processing capabilities of the networks have increased dramatically. The number of real-time applications using these networks has also increased. The large number of real-time packets might, in a switched multi-hop network, lead to unpredictable traffic patterns. This is not a problem when the traffic intensity is low, but if the same network is used by a large number of users simultaneously, the overall performance of the network degrades. In fact, unpredictable delays in the delivery of the message can adversely affect the execution of the tasks dependent on these messages, even if we take into account the soft real-time performance. In this paper, we investigate the effect of traffic shapers on soft real-time performance. We will consider a switched multi-hop network with FCFS queues. We will implement two versions of the network simulator. One version will be without traffic shaper and the other version will use a traffic shaper. By comparing the results (for average delay, deadline miss ratio etc.) from both the versions, we will try to conclude if it is really beneficial to use traffic shapers for soft real-time performance. Leaky bucket and token bucket algorithms are the most popular ones for traffic shaper implementation. We will consider leaky bucket algorithm for our analysis. We analyse different versions of the leaky bucket and present the trade-off’s involved.

This thesis utilized pulse shaping and Gerberg-Saxton algorithm to develop high power tunable narrowband terahertz radiation and applications. By the way of using Freezing algorithm and Gerberg-Saxton, pulse width, pulse duration, pulse position and pulse number can be controlled. The pulse train can be pumping source of high power tunable narrowband terahertz radiation, by avoid the saturations and different pulse duration. The simulation shown the result can have 5GHz narrowband width closing to commercial product. Besides, we demonstrated the THz multi-wavelength interference method by using THz-TDS (terahertz time domain spectroscopy) to measure the liquid crystal cell gap. We have also used THz-TDS to investigate the complex optical constants and birefringence of cholesteric liquid crystal mixture BL006. The extraordinary (ne) and ordinary (no) indices of refraction at are 1.784-1.817 and 1.516-1.555 giving rise to a birefringence of 0.25¡V0.29 in 0.2THz~1.6THz.

Aims Preservation of peri-cervical dentin during the preparation of endodontic access is important to prevent fractures and improve the long-term prognosis. The purpose of this study was to evaluate the impact of rotary file instrumentation (TruNatomy and XP-Endo Shaper) on peri-cervical dentin removal, depending on access size. Materials and Methods Forty 3D printed mandibular first molars, with either a small or large access design, were instrumented using TruNatomy or XP-endo Shaper file systems. Canal volumes were calculated based on micro-computed tomography data obtained pre- and post-operatively. Digital sectioning of each reconstructed volume was performed 90-degrees to the long axis at the floor of the pulp chamber at 5 levels, at the pulp chamber floor (Level 0) as well as 1 and 2mm coronally and apically of Level 0. Linear measurements were taken from the inner wall of the access cavity or canal to the outer surface of the tooth for both instrumentation techniques and compared to the unprepared control dataset. These measurements served as an approximation of remaining peri-cervical dentin after root canal instrumentation. Results Some of the coronal measurements were not reportable for the control group due to incomplete capture of the crown during the microCT scan. The remaining peri-cervical dentin thickness at the level of the pulpal floor and coronally were significantly (p<0.01) affected by the access cavity size, with the smaller access preserving more dentin in all samples. Apical to the pulpal floor, there was no significant difference between instrumentation groups at the data points evaluated. Remaining dentin thickness was largest at coronal section 1 and smallest at apical section 6 with 3.81mm (p = 0.05) and 1.84mm (p = 0.06), respectively. Conclusion Access cavity size had a significant impact on remaining dentin thickness at the level of the pulpal floor and coronally, with more remaining dentin in the conservative access group, irrespective of instrumentation technique. Future studies will evaluate dentin thickness in the furcation and mid root level, as well as apical canal transportation, and procedural errors.

O tratamento endodôntico tem por finalidade primordial oferecer um ambiente favorável para que o organismo possa proporcionar o reparo dos tecidos periapicais possibilitando ao dente o retorno de suas funções. Uma das principais dificuldades de se lograr tal objetivo reside na complexidade anatômica dos canais radiculares, oferecendo sítios de difícil acesso a instrumentos e substâncias químicas, responsáveis pela promoção desse ambiente. Novos instrumentos mecanizados de NiTi foram desenvolvidos propondo diferentes tratamentos térmicos com a finalidade de melhorar a adaptação a canais ovalados, permitindo tocar o maior número de paredes dos canais radiculares. O sistema XP- endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Suíça), recentemente lançado, possui um design inovador, sendo capaz de reagir a variações de temperatura e adquirir uma forma pré-determinada dentro do canal radicular, na temperatura corpórea, bem como atingir áreas inacessíveis para os instrumentos convencionais, tocando os pontos mais dificeis dos canais ovais. O presente estudo tem por objetivos, avaliar o preparo de canais ovais longos de molares inferiores com o sistema XP- endo Shaper comparando-o com instrumentos do sistema Mtwo, por meio da microtomografia computadorizada (?CT). Foram selecionadas 32 raízes distais de molares inferiores divididos aleatoriamente em 2 grupos de 16, de acordo com o método de instrumentação a ser avaliado: Grupo XP - Instrumentação com XP- endo Shaper e Grupo Mtwo - instrumentação com Mtwo. Após a utilização dos softwares Data Viewer, CTan, CTVol foi possível a visualização e análise tridimensional do canal radicular antes e após os procedimentos de preparo-químico cirúrgico, para a comparação do volume de dentina removida, aumento do volume do canal, aumento da área de superfície do canal, superfícies não preparadas do canal, volume de debris e índice de modelo de estrutura (SMI). Os resultados foram submetidos aos testes Shapiro-Wilk e Mann-Whitney. Demonstrando que não houve uma diferença estatística entre os grupos XP-endo Shaper e Mtwo quanto o volume de dentina removida, aumento do volume do canal, aumento da área de superfície do canal, superfícies não preparadas do canal, volume de debris e SMI. Concluiu-se que nenhum sistema estudado foi capaz de tocar todas as paredes de um canal oval longo e que ambas as técnicas se comportam de maneiras semelhantes quanto a do volume de dentina removida, aumento do volume do canal, aumento da área de superfície do canal, SMI, superfícies não preparadas do canal e volume de debris. / Endodontic treatment has the primary purpose of offering a favorable environment so that the body can provide the repair of the periapical tissues enabling the tooth to return to its functions. One of the main difficulties in achieving this objective is the anatomical complexity of the root canals, offering difficult access to instruments and chemical substances responsible for promoting this environment. New NiTi rotatory instruments were developed by proposing different thermal treatments with the purpose of improving the adaptation to oval root canals, allowing instrumenting the largest number of root canal walls. The newly launched XP-endo Shaper system (FKG Dentaire, La Chaux-de-Fonds, Switzerland) has an innovative design, being able to react to temperature variations and acquire a predetermined shape inside the root canal, at body temperature, as well as reaching areas inaccessible to conventional instruments, instrumenting the hardest points of oval canals. The aim of the present study was to evaluate the preparation of long oval canals of mandibular molars with the XP-endo Shaper system, comparing it with the Mtwo system instruments, using micro-computerized tomography (?CT). 32 distal roots of mandibular molars were randomly divided into 2 groups of 16, according to the instrumentation method to be evaluated: XP Group - Instrumentation with XP-endo Shaper and Mtwo Group - instrumentation with Mtwo. After the use of the CTan, CTVol and Data Viewer softwares, it was possible to visualize and analyze three-dimensionally the root canal, before and after the chemical-surgical procedures, to compare the volume of dentin removed, the increase of volume of the canal, the increase of area of the canal surface, unprepared canal surfaces, volume of debris and structure model index (SMI). Results were submitted to the Shapiro-Wilk and Mann-Whitney statistical tests. It was demonstrated that there was no statistically significant difference between the XP-endo Shaper and Mtwo groups, referring to the volume of dentin removed, increase in canal volume, increase in the surface area of the canal, unprepared surfaces of the canal, volume of debris and SMI. We concluded that no studied system was able to touch all the walls of a long oval canal and that both techniques behave in a similar way as the volume of dentin removed, increase in the volume of the canal, increase in the surface area of the canal, SMI, unprepared surfaces of the canal and volume of debris.

Dentre as etapas do tratamento endodôntico, a limpeza e modelagem tem especial atenção, já que a conformação geométrica satisfatória e a sanificação dos canais radiculares propiciam condições favoráveis ao controle da infecção e à adequada obturação do espaço endodôntico. O desenvolvimento de instrumentos fabricados a partir da liga de níquel-titânio (NiTi) contribuiu de maneira importante para a melhora na qualidade e previsibilidade do preparo endodôntico. Os diferentes sistemas mecanizados que são propostos constantemente no mercado devem ser avaliados com detalhes, pois sua performance pode variar de acordo com as características de fabricação e design de cada instrumento. O objetivo deste estudo foi avaliar, por meio da microtomografia computadorizada (micro-CT), o preparo de canais mesiais de molares inferiores com o sistema XP-endo Shaper (XPS), comparando-o ao preparo realizado com instrumentos do sistema Reciproc (REC), quanto ao volume de debris dentinários remanescentes, área de paredes não tocadas, dentina excisada, aumento do volume e superfície do canal radicular e desvio do canal original no terço apical. Vinte e quatro raízes mesiais de molares inferiores, com dois canais e um forame, foram anatomicamente pareadas e divididas em 2 grupos experimentais (n=12) de acordo com o sistema utilizado para o preparo químico cirúrgico: Grupo XPS e Grupo REC. Os espécimes foram escaneados por um microtomógrafo de raios-X (SkyScan 1176) com resolução de 17.42 ?m pré e pós preparo. Com o auxílio dos softwares Dataviewer, CTan e CTVol foi possível a avaliação tridimensional do canal para observação das mudanças nos parâmetros estudados. Os dados obtidos foram comparados e, onde se identificou distribuição normal e homogeneidade das variâncias, foi utilizado o Teste t de student para analisar as hipóteses experimentais. Para os dados onde se observou distribuição não-normal, optou-se pelo teste não-paramétrico numérico (Mann- Whitney). Todos as análises foram realizadas com nível de significância de 5%. Nos resultados, em toda extensão do canal radicular, assim como para as análises por terços, não houve diferença estatisticamente significativa entre os grupos quanto ao transporte do canal, volume de dentina excisada e aumento do volume e superfície do canal. Identificou-se diferença significativa (p < 0,05) entre os grupos quanto a área de superfície não tocada, onde observou-se que, no canal total e nos terços cervical e médio, o grupo XPS preparou maior área do canal do que o grupo REC. Quanto ao volume e percentual de debris dentinários acumulados, o grupo REC apresentou valores estatisticamente maiores na totalidade do canal e nos terços médio e apical, evidenciando maior acúmulo de debris intra-radiculares do que o grupo XPS. Concluiuse que as técnicas de preparo avaliadas se comportaram de maneira semelhante quanto ao aumento de volume e superfície do canal, volume de dentina removida e desvio apical. Em contrapartida, o sistema XPS, por possuir cinemática rotatória excêntrica, conseguiu tocar maior quantidade de paredes e eliminar maior volume percentual de debris acumulados em relação ao sistema que se vale de cinemática reciprocante cêntrica (REC). / Among the stages of endodontic treatment, cleaning and shaping should have special attention, since a satisfactory geometry and sanification of the root canals provide favorable conditions for infection control and adequate endodontic obturation. The development of the Niquel-Titanium (NiTi) instruments contributed to the improvement in quality and predictability of the endodontic preparation. The new mechanized systems that are constantly proposed in the market must be evaluated, as their performance can vary according to the manufacturing and design features of each instrument. The purpose of this study was to evaluate, using microcomputed tomography (micro-CT), the preparation of mesial root canals of mandibular molars with the new XP-endo Shaper (XPS) system comparing it to the preparation performed with Reciproc instruments (REC), evaluating the volume of remaining dentin debris, area of untouched walls, dentin removed, increase in volume and surface of the root canal and apical tranportation. Twenty-four mandibular molar mesial roots with two canals and one foramen were anatomically matched and divided into 2 experimental groups (n = 12) according to the system used for shaping: XPS Group and REC Group. The specimens were scanned pre and post preparation by a X-ray microtomograph (SkyScan 1176) with a resolution of 17.42 ?m. With Dataviewer, CTan and CTVol softwares, it was possible a tridimensional evaluation of the root canal in order to observe changes in the studied parameters. The data were compared and, where normal distribution and homogeneity of variances were identified, Student\'s t test was used to analyze the experimental hypotheses. For the data where non-normal distributions were observed, the non-parametric numerical test (Mann-Whitney) was chosen. All analyzes were performed with a significance level of 5%. In the results, in all extension of the root canal, as well as for analyzes by thirds, there was no statistically significant difference between the groups regarding apical transportation, volume of removed dentin and increase of volume and canal surface. A significant difference (p <0.05) was found between the groups regarding the untouched surface area, where in the total canal and in the cervical and middle thirds, the XPS group prepared a larger area of the canal than the group REC. As to the volume and percentage of accumulated dentinal debris, the REC group presented statistically higher values in the whole canal and in the middle and apical thirds, evidencing a higher accumulation of intra-radicular debris than the XPS group. It was concluded that the preparation techniques evaluated behaved similarly to the changes in volume and surface of the canal, the volume of dentin removed and the apical tranportation. The XPS system by its eccentric rotational kinematics was able to touch a larger number of walls and eliminate a greater percentage volume of accumulated debris compared to the system that uses a centralized reciprocating motion.

Dentre as etapas do tratamento endodôntico, a limpeza e modelagem tem especial atenção, já que a conformação geométrica satisfatória e a sanificação dos canais radiculares propiciam condições favoráveis ao controle da infecção e à adequada obturação do espaço endodôntico. O desenvolvimento de instrumentos fabricados a partir da liga de níquel-titânio (NiTi) contribuiu de maneira importante para a melhora na qualidade e previsibilidade do preparo endodôntico. Os diferentes sistemas mecanizados que são propostos constantemente no mercado devem ser avaliados com detalhes, pois sua performance pode variar de acordo com as características de fabricação e design de cada instrumento. O objetivo deste estudo foi avaliar, por meio da microtomografia computadorizada (micro-CT), o preparo de canais mesiais de molares inferiores com o sistema XP-endo Shaper (XPS), comparando-o ao preparo realizado com instrumentos do sistema Reciproc (REC), quanto ao volume de debris dentinários remanescentes, área de paredes não tocadas, dentina excisada, aumento do volume e superfície do canal radicular e desvio do canal original no terço apical. Vinte e quatro raízes mesiais de molares inferiores, com dois canais e um forame, foram anatomicamente pareadas e divididas em 2 grupos experimentais (n=12) de acordo com o sistema utilizado para o preparo químico cirúrgico: Grupo XPS e Grupo REC. Os espécimes foram escaneados por um microtomógrafo de raios-X (SkyScan 1176) com resolução de 17.42 ?m pré e pós preparo. Com o auxílio dos softwares Dataviewer, CTan e CTVol foi possível a avaliação tridimensional do canal para observação das mudanças nos parâmetros estudados. Os dados obtidos foram comparados e, onde se identificou distribuição normal e homogeneidade das variâncias, foi utilizado o Teste t de student para analisar as hipóteses experimentais. Para os dados onde se observou distribuição não-normal, optou-se pelo teste não-paramétrico numérico (Mann- Whitney). Todos as análises foram realizadas com nível de significância de 5%. Nos resultados, em toda extensão do canal radicular, assim como para as análises por terços, não houve diferença estatisticamente significativa entre os grupos quanto ao transporte do canal, volume de dentina excisada e aumento do volume e superfície do canal. Identificou-se diferença significativa (p < 0,05) entre os grupos quanto a área de superfície não tocada, onde observou-se que, no canal total e nos terços cervical e médio, o grupo XPS preparou maior área do canal do que o grupo REC. Quanto ao volume e percentual de debris dentinários acumulados, o grupo REC apresentou valores estatisticamente maiores na totalidade do canal e nos terços médio e apical, evidenciando maior acúmulo de debris intra-radiculares do que o grupo XPS. Concluiuse que as técnicas de preparo avaliadas se comportaram de maneira semelhante quanto ao aumento de volume e superfície do canal, volume de dentina removida e desvio apical. Em contrapartida, o sistema XPS, por possuir cinemática rotatória excêntrica, conseguiu tocar maior quantidade de paredes e eliminar maior volume percentual de debris acumulados em relação ao sistema que se vale de cinemática reciprocante cêntrica (REC). / Among the stages of endodontic treatment, cleaning and shaping should have special attention, since a satisfactory geometry and sanification of the root canals provide favorable conditions for infection control and adequate endodontic obturation. The development of the Niquel-Titanium (NiTi) instruments contributed to the improvement in quality and predictability of the endodontic preparation. The new mechanized systems that are constantly proposed in the market must be evaluated, as their performance can vary according to the manufacturing and design features of each instrument. The purpose of this study was to evaluate, using microcomputed tomography (micro-CT), the preparation of mesial root canals of mandibular molars with the new XP-endo Shaper (XPS) system comparing it to the preparation performed with Reciproc instruments (REC), evaluating the volume of remaining dentin debris, area of untouched walls, dentin removed, increase in volume and surface of the root canal and apical tranportation. Twenty-four mandibular molar mesial roots with two canals and one foramen were anatomically matched and divided into 2 experimental groups (n = 12) according to the system used for shaping: XPS Group and REC Group. The specimens were scanned pre and post preparation by a X-ray microtomograph (SkyScan 1176) with a resolution of 17.42 ?m. With Dataviewer, CTan and CTVol softwares, it was possible a tridimensional evaluation of the root canal in order to observe changes in the studied parameters. The data were compared and, where normal distribution and homogeneity of variances were identified, Student\'s t test was used to analyze the experimental hypotheses. For the data where non-normal distributions were observed, the non-parametric numerical test (Mann-Whitney) was chosen. All analyzes were performed with a significance level of 5%. In the results, in all extension of the root canal, as well as for analyzes by thirds, there was no statistically significant difference between the groups regarding apical transportation, volume of removed dentin and increase of volume and canal surface. A significant difference (p <0.05) was found between the groups regarding the untouched surface area, where in the total canal and in the cervical and middle thirds, the XPS group prepared a larger area of the canal than the group REC. As to the volume and percentage of accumulated dentinal debris, the REC group presented statistically higher values in the whole canal and in the middle and apical thirds, evidencing a higher accumulation of intra-radicular debris than the XPS group. It was concluded that the preparation techniques evaluated behaved similarly to the changes in volume and surface of the canal, the volume of dentin removed and the apical tranportation. The XPS system by its eccentric rotational kinematics was able to touch a larger number of walls and eliminate a greater percentage volume of accumulated debris compared to the system that uses a centralized reciprocating motion.

In real-time systems spanning a network, there is a need for deterministic communication. The best-effort approach which most of the Internets traffic follows is not suitable for this area since it does not guarantee packet delivery within a deadline and there is also no accurate measure of when the packet was sent. The network core and edge entities such as routers and hosts do not have any concept of time in normal networking, making real-time constraints more difficult to enforce. Time Sensitive Networking is a set of standards, all of which are related to solving the problem above. The most central of these standards is IEEE 802.1AS which defines the generic Precision Time Protocol that specifies how all the nodes of a network should synchronize their clocks to one master clock, giving them a common perception of time. This standard is a prerequisite for some of the other standards in the suite, for example, the 802.1Qbv standard defining a Time Aware Sharper which provides bounded latency for time-critical traffic. A common perception of time is also by itself needed by applications that have to orchestrate actions, with temporal relations to each other, across a network. These applications can be found within areas such as industrial automation and vehicular control systems. The problem that this thesis explores is how the precision of time synchronization of a Time Sensitive Networking (TSN) solution depends on variables in the network such as configuration, topology, and external factors. To find the correlation between the parameters and the precision of the time synchronization, several experiments have been conducted. The experiments were performed on a simple network of hardware components constituting a physical test bed and an oscilloscope was used to probe the clocks if its nodes and extract measurements. Our findings indicate several relationships between the tested parameters and the synchronization precision. The biggest conclusion we can make from our study is that the IEEE 802.1AS standard does not rely on the support of other standards to achieve sub-microsecond results when there is a best-effort traffic load on the network. The manipulated configuration of the standard has given results that in general coincide with the expected behavior. Finally, the data gathered on different topologies, that were tested showed no significant trends regarding the precision. / I realtidssystem som kommunicerar över nätverk finns det ett behov av deterministisk kommunikation. Det vanliga tillvägagångssättet som de mesta av internettrafiken följer är inte lämpligt för detta område eftersom det inte garanterar paketleverans inom en deadline och det inte heller finns något exakt mått av när paketet skickades. Nätverkets enheter som routrar och noder har inte någon uppfattning om tid i normala nätverk, vilket gör realtidsbegränsningar omöjliga att upprätthålla. Time Sensitive Networking är en uppsättning standarder, som alla är relaterade till att lösa problemet ovan. Den mest centrala av dessa standarder är IEEE 802.1AS som definierar generic precision Time Protocol som specificerar hur alla noder i ett nätverk ska synkronisera sina klockor till en masterklicka, vilket ger dem en gemensam tidsuppfattning. Denna standard är en förutsättning för några av de andra standarderna i sviten, till exempel 802.1Qbv-standrarden som definierar en Time Aware Scheduler som ger begränsad latens för tidskritisk trafik. En gemensam tidsuppfattning behövs också av applikationer som måste orkestrera operationer, med tidsmässiga relationer till varandra, över ett nätverk. Dessa applikationer finns inom områden som industriell automation och fordonsstyrningssystem. Problemet som denna avhandling undersöker är hur precisionen av tidssynkronisering av en TSN-lösning beror på variabler i nätverket så som konfiguration, topologi och externa faktorer. För att hitta korrelationen mellan parametrarna och precisionen i tidssynkroniseringen har flera experiment genomförts. Experimenten utfördes på ett enkelt nätverk av hårdvarukomponenter som utgör en fysisk testbädd och ett oscilloskop användes för att undersöka klockorna på dess noder och extrahera mätningarna. Våra resultat indikerar flera samband mellan de testade parametrarna och synkroniseringsprecisionen. Den största slutsatsen vi kan dra från vår studie är att IEEE 802.1AS-standaden inte förlitar sig på stöd från andra standarder för att uppnå resultat under mikrosekunder när det finns en annan trafikbelastning på nätverket. Den manipulerade konfigurationen av standarden har gett resultat som i allmänhet överensstämmer med det förväntade beteendet. Slutligen visade de insamlade data om olika typologier som testades inga signifikanta trender vad gäller precisionen.

Doctor of Philosophy / Department of Physics / Zenghu Chang / The few-cycle femtosecond laser pulse has proved itself to be a powerful tool for controlling the electron dynamics inside atoms and molecules. By applying such few-cycle pulses as a driving field, single isolated attosecond pulses can be produced through the high-order harmonic generation process, which provide a novel tool for capturing the real time electron motion. The first part of the thesis is devoted to the state of the art few-cycle near infrared (NIR) laser pulse development, which includes absolute phase control (carrier-envelope phase stabilization), amplitude control (power stabilization), and relative phase control (pulse compression and shaping). Then the double optical gating (DOG) method for generating single attosecond pulses and the attosecond streaking experiment for characterizing such pulses are presented. Various experimental limitations in the attosecond streaking measurement are illustrated through simulation. Finally by using the single attosecond pulses generated by DOG, an attosecond transient absorption experiment is performed to study the autoionization process of argon. When the delay between a few-cycle NIR pulse and a single attosecond XUV pulse is scanned, the Fano resonance shapes of the argon autoionizing states are modified by the NIR pulse, which shows the direct observation and control of electron-electron correlation in the temporal domain.

To capture electronic rearrangements inside a molecule or during chemical reactions, attosecond (as, 1 as =10−18 s) time resolution is needed. To create a light pulse with this duration, the central frequency has to be in the XUV range and cover several tens of eVs. Moreover, the frequency components have to be synchronized. The so called High Harmonic Generation (HHG) in gases well suits this task. During this process a high intensity laser pulse is focused in a gas jet, where its electric field bends the potential barrier of an atom allowing an electron wave packet (EWP) to tunnel ionize. Following the electric field of the laser the EWP gets accelerated, gaining a large kinetic energy that may be released as a high energy (XUV) photon in the event of a re-collision with the ionic core. These recolliding EWP probe the structure and dynamics of the core in a self-probing scheme: the EWP, that is emitted by the molecule at a certain time, probes itself later. More precisely, this "self-probing" scheme gives access to the complex valued recombination dipole moment (RDM) of the molecule which is determined by both the nuclear and electronic structure. The recombination encodes these characteristics into the spectral amplitude, phase and polarization state of the harmonic radiation emitted by the dipole. Due to the coherent nature of HHG it is possible to measure all these three parameters. Moreover, it is in principle possible through a tomographic procedure to reconstruct the radiating orbital.The objective of my thesis was two-fold. By implementing advanced characterization techniques of the harmonic amplitude, phase and polarization we studied i) the electronic structure of N2 and laser induced multi-channel tunnel ionization. We presented the reconstruction of molecular orbitals and revealed the ionization channel dependent ultrafast nuclear vibration. We also studied ii) the reflectivity and dispersion of recently designed chirped XUV mirrors that can shape the temporal profile of attosecond pulses. With these mirrors we could control the spectral phase over 20 eV and compensate the GDD of the harmonics or introduce a TOD. We also proposed a novel attosecond pulse shaper.