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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
541

NÁVRH OPTOVLÁKNOVÉHO BIOSENZORU SE SPEKTRÁLNÍ ANALÝZOU V BLÍZKÉ INFRAČERVENÉ OBLASTI / DESIGN OF FIBER-OPTIC BIOSENSOR WITH NEAR-INFRARED SPECTRAL ANALYSIS

Křepelka, Pavel January 2019 (has links)
This thesis deals with a measurement and interpretation of NIR spectra of bacterial cells and design of biosensor using this analytical technique. In the first chapter, there is introduction of current state of knowledge in the field of NIR spectroscopy in microbiology and technology of fiber optic biosensors. The summary of this chapter shows that NIR is a suitable technique for direct molecular analysis of bacteria, but it suffers from low sensitivity and insufficient interpretation of bacterial spectra. In the next part of the thesis, there is a theoretical background of spectral analysis techniques and technology of fiber optic sensors. In the practical part of this work, there is suggested the elimination of disadvantages of NIR spectroscopy in microbiology by a series of experiments used for interpretation of NIR spectra of bacteria and design of fiber optic sensor to increase sensitivity of this technique. In this work, spectral regions important for the identification of bacterial strains were determined and partially interpreted and the sensor for bacterial analysis capable of classifying strains based on 105 captured cells was designed. Therefore, the objectives of this work were fulfilled.
542

Výkonnostní analýza programů založená na vkládání šumu / Performance Analysis Based on Noise Injection

Liščinský, Matúš January 2021 (has links)
Táto práca predstavuje nástroj Perun-Blower, využívajúci perfblowing techniku: vkladanie šumu do funkcií testovaného programu a nasledovné vyhodnotenie vplyvu šumu na výkon programu na základe zozbieraných časových údajov týchto funkcií z behu programu. Implementácia je postavená na dynamickej binárnej inštrumentácii nástroja Pin. Zameriavame sa na hľadanie funkcií, ktoré majú vysoký vplyv na výkon a rovnako tak aj odhad potenciálneho zrýchlenia behu vlákna pri optimalizácii konkrétnej funkcie. Naviac sme rozšírili existujúci Trace collector používaný v nástroji Perun na zbieranie časových dát funkcií, o nový tzv. engine, ktorý je založený práve na nástroji Pin. Funkčnosť implementácie sme otestovali na dvoch netriviálnych projektoch, kde sme dokázali nájsť funkcie (1) so značným vplyvom na výkon, (2) s najvýznamnejším optimalizačným prínosom a (3) funkcie, ktorých degradácia spôsobí, že vykonávanie programu sa neskončí ani po niekoľkých hodinách.
543

Assignment of the human homeobox 11-like 2 gene (HOX11L2) to chromosome 5q34→q35 by radiation hybrid mapping

Lee-Kirsch, Min-Ae, Engel, Kerstin, Paditz, Ekkehart, Rösen-Wolff, Angela, Lee, Young-Ae, Gahr, Manfred January 2001 (has links)
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
544

Diode-Pumped High-Energy Laser Amplifiers for Ultrashort Laser Pulses The PENELOPE Laser System

Löser, Markus 16 November 2017 (has links)
The ultrashort chirped pulse amplification (CPA) laser technology opens the path to high intensities of 10^21 W/cm² and above in the laser focus. Such intensities allow laser-matter interaction in the relativistic intensity regime. Direct diode-pumped ultrashort solid-state lasers combine high-energy, high-power and efficient amplification together, which are the main advantages compared to flashlamp-pumped high-energy laser systems based on titanium-doped sapphire. Development within recent years in the field of laser diodes makes them more and more attractive in terms of total costs, compactness and lifetime. This work is dedicated to the Petawatt, ENergy-Efficient Laser for Optical Plasma Experiments (PENELOPE) project, a fully and directly diode-pumped laser system under development at the Helmholtz–Zentrum Dresden – Rossendorf (HZDR), aiming at 150 fs long pulses with energies of up to 150 J at repetition rates of up to 1 Hz. The focus of this thesis lies on the spectral and width manipulation of the front-end amplifiers, trivalent ytterbium-doped calcium fluoride (Yb3+:CaF2) as gain material as well as the pump source for the final two main amplifiers of the PENELOPE laser system. Here, all crucial design parameters were investigated and a further successful scaling of the laser system to its target values was shown. Gain narrowing is the dominant process for spectral bandwidth reduction during the amplification at the high-gain front-end amplifiers. Active or passive spectral gain control filter can be used to counteract this effect. A pulse duration of 121 fs was achieved by using a passive spectral attenuation inside a regenerative amplifier, which corresponds to an improvement by a factor of almost 2 compared to the start of this work. A proof-of-concept experiment showed the capability of the pre-shaping approach. A spectral bandwidth of 20nm was transferred through the first multipass amplifier at a total gain of 300. Finally, the predicted output spectrum calculated by a numerical model of the final amplifier stages was in a good agreement with the experimental results. The spectroscopic properties of Yb3+:CaF2 matches the constraints for ultrashort laser pulse amplification and direct diode pumping. Pumping close to the zero phonon line at 976nm is preferable compared to 940nm as the pump intensity saturation is significantly lower. A broad gain cross section of up to 50nm is achievable for typical inversion levels. Furthermore, moderate cryogenic temperatures (above 200K) can be used to improve the amplification performance of Yb3+:CaF2. The optical quality of the doped crystals currently available on the market is sufficient to build amplifiers in the hundred joule range. The designed pump source for the last two amplifiers is based on two side pumping in a double pass configuration. However, this concept requires the necessity of brightness conservation for the installed laser diodes. Therefore, a fully relay imaging setup (4f optical system) along the optical path from the stacks to the gain material including the global beam homogenization was developed in a novel approach. Beside these major parts the amplifier architecture and relay imaging telescopes as well as temporal intensity contrast (TIC) was investigated. An all reflective concept for the relay imaging amplifiers and telescopes was selected, which results in several advantages especially an achromatic behavior and low B-Integral. The TIC of the front-end was improved, as the pre- and postpulses due to the plane-parallel active-mirror was eliminated by wedging the gain medium.
545

Dynamic amplification for moving vehicle loads on buried pipes : Evaluation of field-tests

Smagina, Zana January 2001 (has links)
No description available.
546

Tailoring the properties of metamaterials for linear and nonlinear applications

Sydoruk, Oleksiy 13 June 2007 (has links)
The thesis is devoted to magnetic metamaterials operating in the frequency range of 10 MHz 1 GHz. Mechanisms of tailoring the properties of metamaterials are developed and a number of linear and nonlinear applications is proposed.In Chapter 1, the introduction to the field of metamaterials is given and the main goal of the thesis is defined as the search for possible applications of low-frequency metamaterials. The main motivation is the potential of magnetic metamaterials in Magnetic Resonance Imaging (MRI).Chapter 2 briefly summarizes the near-field properties of magnetic metamaterials. Magnetic coupling between a pair of metamaterial elements is described and magnetoinductive (MI) waves propagating on the metamaterials arrays are introduced.In Chapter 3, the magnetic coupling between the elements is studied in more detail. Based on the analogy between MI waves and acoustic waves in solids, "diatomic" metamaterial arrays having two elements per unit cell are introduced. It is shown that by changing the resonant frequencies of the elements and the coupling between them it is possible to acquire additional freedom in tailoring the dispersion properties of MI waves compared to simple "monatomic" configurations.In Chapter 4, various linear applications of metamaterials are discussed. They are shift-dependent transmission, subwavelength imaging and focusing, and rotational resonance of MI waves. It is shown that the microscopic model based on taking the interaction between the elements into account allows for reliable explanation of the phenomena studied.In Chapter 5, a nonlinear application, parametric amplification of MI waves, is discussed. It is shown that parametric amplification can lead to the compensation of loss in metamaterials and to increase of the power extracted from an MRI detection system.Conclusions are drawn and possible directions for future work are determined in Chapter 6.
547

Análisis de la amplificación sísmica de edificios del Cercado de Lima – Lima y La Punta – Callao por medio del método modal espectral y tiempo – historia mediante acelerogramas sintéticos / Analysis of the seismic amplification of the buildings in Cercado de Lima - Lima and La Punta - Callao by modal response spectrum analysis and time-history analysis by synthetic accelerograms

Castillo Cano, Ronald Daniel, Young del Aguila, Fredy Renan 30 November 2019 (has links)
Actualmente la población limeña no cuenta con viviendas propias y seguras; por ello, surge el auge del rubro de la construcción masiva con grandes edificaciones multifamiliares, cuya resistencia al impacto telúrico de enorme magnitud de 8 a 9 grados sigue en prueba sísmica; por ende, es muy relevante realizar la comparación del análisis del método modal espectral de la estructura (desplazamientos y aceleraciones respecto al suelo) y un análisis del método tiempo-historia donde se obtendrán las deformaciones máximas de la estructura de los edificios en este presente estudio; asimismo, evaluará la vulnerabilidad de la construcción estructural mediante acelerogramas sintéticos utilizando como espectro objetivo el espectro de peligro uniforme obtenido en el Parque de la Reserva, Cercado de Lima, por medio de un estudio peligro sísmico para un periodo de retorno de 475 años, reconociendo el comportamiento estructural ante un sismo de gran magnitud. El presente estudio titulado: Análisis de la amplificación sísmica de edificios del Cercado de Lima – Lima y La Punta – Callao por medio del análisis modal espectral y tiempo – historia mediante acelerogramas sintéticos; cuyo objetivo es realizar la comparación de dichos métodos en 4 edificios (2 de 5 niveles y 2 de 12 niveles) cuya configuración estructural es de muros de concreto armado, los cuales se estudiaran en dos distintos tipos de suelo (Cercado de Lima y La Punta) con la finalidad de obtener resultados de derivas, fuerzas, desplazamientos y aceleraciones para determinar la amplificación sísmica en los suelos mencionados, y así optar por el método de análisis más óptimo. Asimismo, el propósito del presente estudio es conocer el comportamiento de la edificación acorde con la realidad peruana; es decir edificaciones con periodos cortos; el cual evaluará la vulnerabilidad mediante acelerogramas sintéticos, reconociendo el comportamiento estructural ante una eventualidad sísmica de gran magnitud. / Currently, the population of Lima does not have their own and secure homes; For this reason, the boom in the field of massive construction emerges with large multi-family buildings, whose resistance to the telluric impact of enormous magnitude of 8 to 9 degrees continues in seismic testing; therefore, it is very relevant to make the comparison of the analysis of the spectral modal method of the structure (displacements and accelerations with respect to the ground) and an analysis of the time-history method where the maximum deformations of the structure of the buildings will be obtained in this present study. ; Likewise, it will assess the vulnerability of structural construction using synthetic accelerograms using the uniform hazard spectrum obtained in Parque de la Reserva, Cercado de Lima as the objective spectrum, through a seismic hazard study for a return period of 475 years, recognizing structural behavior in the face of a large earthquake. The present study entitled: Analysis of the seismic amplification of buildings in Cercado de Lima - Lima and La Punta - Callao by means of spectral modal analysis and time - history using synthetic accelerograms; the objective of which is to compare these methods in 4 buildings (2 of 5 levels and 2 of 12 levels) whose structural configuration is made of reinforced concrete walls, which will be studied in two different types of soil (Cercado de Lima and La Punta ) in order to obtain results of drifts, forces, displacements and accelerations to determine the seismic amplification in the mentioned soils, and thus opt for the most optimal analysis method. Likewise, the purpose of this study is to know the behavior of the building in accordance with the Peruvian reality; that is to say buildings with short periods; which will assess vulnerability using synthetic accelerograms, recognizing the structural behavior in the event of a large seismic event. / Tesis
548

Étude et réalisation d'un duplexeur SOI accordable multibande pour les futures générations de systèmes de téléphonie mobile / Study and design of a tunable SOI duplexer multiband for future generations of mobile systems

Settaf, Zakaria 16 December 2016 (has links)
Plusieurs standards de téléphonie mobile ont été définis et sont utilisés actuellement. Dans un avenir proche, avec le développement de la 5G de nouveaux standards et de nouvelles bandes de fréquence faire leur apparition. De ce fait, avec l'utilisation de nombreux circuits dédiés à un standard et donc à une bande de fréquence, des difficultés d'intégration et desproblèmes de coûts apparaissent. Il est donc devenu nécessaire pour les concepteurs de proposer des circuits intégrés reconfigurables pour plusieurs gammes de fréquences avec des modes de fonctionnement différents.Dans un système d'émetteur récepteur, le duplexeur permet l'établissement d'une communication simultanée en utilisant une seule antenne pour la transmission et la réception de données, sans que celles-ci soient corrompues. C'est un composant vital, surtout pour la chaine de réception car la réception du signal désiré dépend de ses caractéristiques. Ce dispositif est conçu sur du matériau piézoélectrique, qui ne permet pas d'obtenir un filtre agile en fonction de la fréquence. Dans ce contexte, il est intéressant de rechercher une nouvelle architecture de duplexeur, permettant une réalisation intégrée et un fonctionnement agile.Plusieurs architectures de duplexeur ont été retenues en se basant sur des études récentes menées dans différentes équipes de recherche. Un classement de ces architectures a été proposé, avec des améliorations pour les rendre intégrables et reconfigurables. Parmi toutes les solutions de duplexeurs passifs étudiées, le duplexeur à coupleur hybride 3dB est unesolution permettant d'obtenir des performances attractives. Les simulations pour différentes bandes de fréquences ont montré qu’il était difficile de respecter les spécifications de l’isolation Tx/Rx. Des solutions possibles ont été présentées et des modifications de la structure d'un amplificateur du LNA ont été évaluées en simulation. Ainsi, les performancesd’isolation peuvent être améliorées grâce à des structures actives d’annulation du signal résiduel Tx.La conception, la réalisation et le test de coupleurs hybrides et duplexeurs sont présentés. Le circuit a été implémenté en utilisant la technologie SOI 0.13 micromètre de ST Microelectronics et mesuré avec un boitier BT soudé sur un support de test PCB. Les performances RF du duplexeur peuvent être ajustées en fonction de la bande de fréquence désirée grâce aux capacités commutées. Les performances RF du coupleur hybride 3dB permettent d’envisager l’application de la structure proposée pour les futurs développements de systèmes de téléphonie. / Several standards have been defined and are currently used on mobile phones. With the high request for the broadband, several new standards are developed and introduced in 5G. This results in the use of many circuits, dedicated to one standard and thus one frequency band, which increase the difficulty of integrating these dedicated circuits and therefore costly. It hasbecome necessary for designers to propose tunable integrated circuit that can address several frequency ranges with different operating modes.The duplexer allows the establishment of simultaneous communications, using a single antenna for sending and receiving data, without any interferences. It is a vital component, especially for receiver. In fact, the quality of the received signal depends greatly on the duplexer characteristics. This device is designed on the piezoelectric material, which does not allow to achieve a tunable filter according to the frequency. In this context, it seems interesting to study a new architecture of duplexer. Therefore, it is necessary to define the duplexer function based on studies and system simulations, thus identify the constraints and technology limitations. Several duplexer architectures were selected based on recent studies in different research teams.A classification of these architectures was proposed and also improvements to make them integrated and tunable. Among all the solutions studied, the duplexer using hybrid 3dB coupler shown the most attractive performance. Simulations for different frequency bands showed that it's difficult to achieve Tx/Rx isolation requirements. Different solutions have been presented and LNA structure have been changed and thus evaluated by simulations. Thanks to that, the Tx/Rx isolation can be improved through active cancellation structures.The final chapter presents the design, implementation and testing of hybrid 3dB coupler and duplexer. It has been implemented using SOI 0.13 micrometer from ST Microelectronics and tested on BT-resin substrat. The RF performance of the duplexer can be corrected according to the desired frequency band through the switched capacitor. The RF performance of the hybrid 3dB coupler is in the line with expectations and allows to consider its integration in future system developments.
549

Synchronization In Advanced Optical Communications

Kim, Inwoong 01 January 2006 (has links)
The objective of this dissertation is to generate high power ultrashort optical pulses from an all-semiconductor mode-locked laser system. The limitations of semiconductor optical amplifier in high energy, ultrashort pulse amplification are reviewed. A method to overcome the fundamental limit of small stored energy inside semiconductor optical amplifier called "eXtreme Chirped Pulse Amplification (X-CPA)" is proposed and studied theoretically and experimentally. The key benefits of the concept of X-CPA are addressed. Based on theoretical and experimental study, an all-semiconductor mode-locked X-CPA system consisting of a mode-locked master oscillator, an optical pulse pre-stretcher, a semiconductor optical amplifier (SOA) pulse picker, an extreme pulse stretcher/compressor, cascaded optical amplifiers, and a bulk grating compressor is successfully demonstrated and generates >kW record peak power. A potential candidate for generating high average power from an X-CPA system, novel grating coupled surface emitting semiconductor laser (GCSEL) devices, are studied experimentally. The first demonstration of mode-locking with GCSELs and associated amplification characteristics of grating coupled surface emitting SOAs will be presented. In an effort to go beyond the record setting results of the X-CPA system, a passive optical cavity amplification technique in conjunction with the X-CPA system is constructed, and studied experimentally and theoretically.
550

Quantification of DNA Nanoballs Using Image Processing Techniques

Lindberg, Sara January 2023 (has links)
In gene editing, it is important to identify the number of edited and unedited nucleic acids in the development of new therapies and drugs. Countagen is developing a technology for accelerating genomic research and their product is called GeneAbacus. The product is a consumable reagent kit for the quantification of nucleic acids, which can be used by CRISPR gene editing researchers. The DNA which is analyzed with the reagent kit is first extracted in an assay and then targeted with tailored padlock probes. The target region is amplified via RCA and the products collapse into a fluorescent DNA nanoball, which can be analyzed with a fluorescence microscope. Each fluorescent dot in the microscope corresponds to a single recognition event, making the quantification of the edited and unedited nucleic acids possible.  The purpose of this project was to count the number of DNA nanoballs in images from a fluorescence microscope with a focus on deep learning. To do this, the images were first preprocessed to enhance the image quality and then cropped into small patches, before the patches were manually annotated on image-level. The mean value from three annotators was used as the label and the labelled images were used to train a ResNet by using a regression- based approach. PyTorch and the API Fastai were used for training and the applied method was transfer learning. The network was trained in two stages: first, the newly added layers were trained for feature extraction, and then the pre-trained base model was unfrozen and trained for fine-tuning. To find the position of the nanoballs in the images, Class Activation Maps (CAMs) and Gradient-weighted Class Activation Mapping (Grad-CAMs) were created, and the local maxima were calculated to produce statistics.  The best-performing model was a ResNet34 trained with batch size 32 and the loss function Huber loss. The model inference showed that the deep learning model counted the nanoballs in the same interval as the observers in 40 of 50 test images. The created CAMs and Grad-CAMs had too low resolution to find the coordinates of the detected nanoballs.  During this project, the nanoballs were only counted in small patches, but the goal was to find nanoballs in a large image. This project has been limited by time and unfortunately, the step where the number of nanoballs in the different patches were to be summed was not performed. However, the study showed that it is possible to implement and train a deep learning model to count nanoballs in small patches. It also showed that the activation maps had too low resolution to be able to find the positions of the nanoballs by looking for local maxima. The results showed that the number of patches used as training samples did not greatly impact the model’s performance when comparing 300 patches and 450 patches. Manual annotation of nanoballs was a difficult task since the nanoballs are moving when the images are taken, which results in unsharp nanoballs in some patches. Therefore, the manual annotation should probably be performed by experts to get the correct labels for the training. To improve the model and be able to find the positions of the nanoballs further investigation is needed.

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