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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.
321

Strukturintegrierbare Sensoren auf Basis piezoelektrischer Polymere / Sensors Based on Piezoelectric Polymers for Structure Integration

Schulze, Robert 07 August 2017 (has links) (PDF)
Die vorliegende Arbeit beschreibt die Entwicklung von Sensoren in einer neuen, großserienfähigen Technologie. Mit dem Mehrkomponentenmikrospritzgießverfahren werden mechanische Sensorstrukturen aus (faserverstärktem) Kunststoff an polymere piezoelektrische Wandler angebunden. Die hergestellten Aufnehmer können über die Weiterverarbeitung mit Hybridtechnologien für die Strukturintegration eingesetzt werden. Diese Dissertation stellt Entwurfsmethoden und Modelle zur Vorausberechnung der neuartigen Sensoren bereit, die zur Qualifizierung der neuen Technologie benötigt werden. Dazu werden bekannte Modellierungsansätze angewandt und wesentliche Erweiterungen für die praktische Nutzung erarbeitet. Entwurfsrelevante technologieabhängige Kenngrößen, wie die elastischen Eigenschaften der verarbeiteten Werkstoffe und die geometrischen Dimensionen der hergestellten Sensorstrukturen werden untersucht und deren Einfluss auf den Entwurfsprozessdargelegt. Die hergestellten Sensoren werden in ihrer Grundfunktion messtechnisch charakterisiert und die System- und Strukturintegration vorgestellt. / The presented work describes the development of sensors in a novel technology approach feasible for large-scale production. By using the multicomponent microinjection molding process, mechanical sensor structures out of (fiber-reinforced) polymers are joined with piezoelectric polymer transducers. The fabricated sensors can be processed further with hybrid manufacturing technologies and adapted for structure integration. This thesis introduces design methods and models for the preliminary calculation of the novel sensors, which are required for a technology qualification. Therefore, existing modelling approaches adapted and essentially extended for practical use. Design relevant parameters related to the technology like the elastic properties of the applied materials or the geometric dimensions of the manufactured sensor structures are characterized and the system and structure integration of the sensors is presented.
322

Applications thérapeutiques des ultrasons focalisés de haute intensité à l’unité placentaire / Application of high intensity focused ultrasound applied to the placental unit

Caloone, Jonathan 05 December 2017 (has links)
Objectifs : Développer un traitement HIFU (High-Intensity Focused Ultrasound) des anomalies placentaires au moyen d’un transducteur torique. Les essais ont été menés à partir d’un modèle ex-vivo, puis la faisabilité, l’efficacité et l’innocuité du traitement a été évaluée sur un modèle de guenons gestantes. Les premières applications thérapeutiques envisagées à l’échelle humaine, concernent le traitement du syndrome transfuseur-transfusé (STT) et les accrétions placentaires pour lesquelles un protocole d’essai clinique a été établi. Matériels et méthodes : Un transducteur torique fonctionnant à 3 MHz et muni d’une cellule d’imagerie échographique intégrée fonctionnant à 7,5 MHz ont été utilisés. Des simulations numériques de séquences de traitement HIFU ont été menées à partir d’une étude préliminaire sur la caractérisation acoustique du tissu placentaire humain. Ces séquences ont été testées au cours d’une étude ex-vivo sur des placentas humains. Deux modèles ex-vivo ont été conçus. Dans un premier temps, un modèle de traitement extracorporis. Dans un second temps, des traitements HIFU ont été réalisés à des distances variables du transducteur, par modification de la taille du ballonnet, afin de simuler un traitement per-césarienne. Le transducteur était placé au contact de la face foetale du placenta afin de simuler la séreuse utérine. A partir des résultats issus de ces essais ex-vivo, un protocole in-vivo sur des guenons gestantes a été mené afin de valider la faisabilité, l’efficacité et l’innocuité de la réalisation de lésions HIFU dans le placenta de guenons gestantes de manière totalement non-invasive. La qualité du monitoring échographique était évaluée au cours des trois études, et corrélée à l’analyse macroscopique. Une étude histologique a également été menée. Résultats : L’atténuation placentaire a été mesurée à partir de 12 échantillons placentaires humains pour un âge gestationnel compris entre 17 et 40 semaines d’aménorrhées (SA). L’atténuation augmentait en fonction de l’âge gestationnel et était compris entre 0,072 et 0,098 Np.cm-1.MHz-1. Lors d’un premier essai ex-vivo, 33 échantillons placentaires humains ont été inclus et soumis à une séquence HIFU, le temps d’insonification était de 55 secondes, la puissance acoustique utilisée était de 90 Watts. Au total, vingt-cinq lésions élémentaires étaient produites pour un diamètre et une profondeur moyens respectifs de 7,1 ± 3,2 et de 8,0 ± 3,1 millimètres. Huit lésions HIFU ont également été produites à partir de la juxtaposition de 6 tirs, pour un diamètre et une profondeur moyenne respectifs de 23,0 ± 5,0 et 11,0 ± 4,7 millimètres. Aucune lésion située en amont de la lésion produite n’a été observée pour une épaisseur de paroi abdominale similaire à celle d’une guenon gestante (10,8 ± 1,7 millimètres). Dans un second temps, 8 placentas humains pour un âge gestationnel compris entre 39 et 40 SA, ont été soumis à une séquence de traitement HIFU sans interposition de paroi abdominale. Le temps d’exposition était de 75 secondes pour une puissance acoustique de 90 Watts. Les lésions placentaires ont été produites à 2 (n=4), 6 (n=4), 7 (n=4) et 8 (n=7) millimètres de la surface du placenta. Au total, 19 lésions placentaires ont été produites, pour un diamètre et une profondeur moyenne respectifs de 14,6 ± 2,1 et de 14,1 ± 2,3 millimètres. Au cours de l’étude in-vivo, 8 guenons ont été incluses pour un âge gestationnel moyen de 72 ± 4 jours. Les puissances acoustiques utilisées étaient de 65, 80, 110 et 120 Watts pour un temps de traitement de 30, 15, 20 et 20 secondes respectivement. Au total 6 lésions placentaires ont été produites à l’issu de 13 insonifications pour des diamètres moyens de 6,4 ± 0,5 mm, 7,8 ± 0,7 mm et une profondeur moyenne de 3,8 ± 1,5 mm [etc…] / Objectives: To develop a High-intensity Focused Ultrasound (HIFU) treatment for placental abnormalities. Trials were first conducted using an ex-vivo model. Then the safety, feasibility and efficacy were demonstrated using a pregnant monkey model. The first therapeutic applications for human concern the treatment of the twin-to-twin transfusion syndrome (TTTS) and placenta accreta, for which, a clinical trial has already been established. Materials and Methods: A toroidal HIFU transducer, with an integrated ultrasound imaging probe was used. Numerical simulations have allowed identifying HIFU treatment parameters based on a preliminary experiment measuring the acoustic attenuation of human placentae. These HIFU parameters were tested during an ex-vivo study on human placentae. Two models were used. First, an extracorporis model of treatment was developed. Second, a percesarean model was developed. HIFU lesions were performed at different distances from the transducer, by adjusting the quantity of water between the transducer and tissues. The transducer was placed in contact with the fetal side of the placenta in order to simulate the uterine serosa. Using the results of these studies, an in-vivo study was conducted in a pregnant monkey model. The aim was to evaluate the feasibility, the efficacy and the harmlessness of the HIFU treatment applied to the placenta non invasively. The ultrasound monitoring was assessed during these three studies, and was correlated to the macroscopic examination. A histological study was also performed. Results: The placental attenuation was measured using 12 placental samples for a gestational age from 17 to 40 weeks of gestation (WG). The attenuation coefficient increased according to the gestational age, and was ranged from 0,072 to 0,098 Np.cm-1.MHz-1. During the first experimental ex-vivo study, 33 human placental samples were included and treated with HIFU. The treatment parameters were an exposure time of 55 seconds and an acoustic power of 90 Watts. Twenty-five HIFU singles lesions were created with an average diameter and depth of 7.1 ± 3.2 and 8.0 ± 3.1 millimeters, respectively. Eight HIFU lesions were also created by juxtaposing 6 single HIFU lesions. The average diameter and depth of these juxtaposed lesions were 23.0 ± 5.0 and 11.0 ± 4.7 millimeters, respectively. No secondary lesion was observed in overlying abdominal tissues. The thickness of these intervening tissues was similar to a pregnant monkey (10.8 ± 1.7 millimeters). In a second set of experiments, 8 human placentae for a gestational age ranging between 39 and 40 weeks were treated without intervening tissues. The time of exposure was 75 seconds and the acoustic power was 90 Watts. The placental lesions were created at 2 (n=4), 6 (n=4), 7 (n=4) and 8 (n=7) millimeters from the surface of the placenta. In total, 19 placental lesions were created with an average diameter and depth of 14.6 ± 2.1 and 14.1 ± 2.3 millimeters, respectively. Eight pregnant monkeys were included in the in-vivo experiments. The average gestational age was 72 ± 4 days. The placenta was treated non-invasively with acoustic powers of 65, 80, 110 and 120 Watts for a time of exposure of 30, 15, 20 and 20 seconds, respectively. In total, 6 placental lesions were created from 13 insonifications. The average diameters and depths of these lesions were 7.8 ± 0.7 and 3.8 ± 1.5 mm, respectively. No significant variation in maternal or fetal parameters was observed. All placental lesions appear hyperechoic in sonograms and well correlated with the macroscopic measurements. The ultrasound monitoring was better invivo when compared with ex-vivo results. The histological examination demonstrated a well delimited lesion of coagulation in all cases
323

Muscle Wasting in a Rat ICU Model : Underlying Mechanisms and Specific Intervention Strategies

Salah, Heba January 2017 (has links)
Critical care has undergone several developments in the recent years leading to improved survival. However, acquired muscle weakness in the intensive care unit (ICU) is an important complication that affects severely ill patients and can prolong their ICU stay. Critical illness myopathy (CIM) is the progressive decline in the function and mass of the limb muscles in response to exposure to the ICU condition, while ventilator-induced diaphragm dysfunction (VIDD) is the time dependent decrease in the diaphragm function after the initiation of mechanical ventilation. Since the complete underlying mechanisms for CIM and VIDD are not completely understood, there is a compelling need for research on the mechanisms of CIM and VIDD to develop intervention strategies targeting these mechanisms. The aim of this thesis was to investigate the effects of several intervention strategies and rehabilitation programs on muscle wasting associated with ICU condition. Moreover, muscle specific differences in response to exposure to the ICU condition and different interventions was investigated. Hence, a rodent ICU model was used to address the mechanistic and therapeutic aspects of CIM and VIDD. The effects of heat shock protein 72 co-inducer (HSP72), BGP-15, on diaphragm and soleus for rats exposed to different durations of ICU condition was investigated. We showed that 5 and 10 days treatment with BGP-15 improved diaphragm fiber and myosin function, protected myosin from posttranslational modification, induced HSP72 and improved mitochondrial function. Moreover, BGP-15 treatment for 5 days improved soleus muscle fibers function, improved mitochondrial structure and reduced the levels of some ubiquitin ligases. In addition to BGP-15 treatment, passive mechanical loading of the limb muscles was investigated during exposure to the ICU condition. We showed that mitochondrial dynamics and mitophagy gene expression was affected by Mechanical silencing while mechanical loading counteracted these effects. Our investigation for other pathways that can be involved in muscle wasting associated with ICU condition showed that the Janus kinase 2/ Signal transducer and activator of transcription 3 (JAK2/STAT3) pathway is differentially activated in plantaris, intercostals and diaphragm. However, further studies are required with JAK2/STAT3 inhibitors to fully examine the role of this pathway in the pathogenesis of CIM and VIDD prior to translation to clinical research.
324

Rotator assembly at Indexator

Lundström, Jonathan, Hörnberg, Emil January 2017 (has links)
The thesis is concerning rotator assembly at Indexator. A need to increase production has been seen and it can be done by implementing an optimized assembly process. In addition to the assembly process a new design on workstations and new test equipment is needed.The study resulted into three assembly process proposals. The processes were balanced, layouts were produced and Plant simulation was utilized to produce simulation models. Each proposal were analyzed based on cost, performance, ease of implementation, flexibility and worker condition. This resulted in a stationary assembly process being most promising and a 3D simulation model was produced for visualization and better understanding. The stationary assembly process has a capacity for 90 rotators per day, while reducing the amount of workers by one.The layout of the workstations was done based on the assembly process layout and further developed to make the work cell lean and ergonomic. It resulted in three workstations to perform the assembly. The test bench was developed by creating target specifications, establish a test procedure and decide components for the test bench layout. The finished test bench can measure dynamic torque, count particles to ensure cleanliness and is able to run the test unattended. / Examensarbetet handlar om montering av rotatorer på Indexator. Målet är att ta fram en optimerad monteringsprocess som kan implementeras i Indexators fabrik utan svårigheter. Den nya monteringsprocessen kommer kräva en ny design på arbetsstationerna och nya testbänkar.Fyra koncept på monteringsprocessen togs fram, baserat på monteringens behov och målsättning. Efter utvärdering så modifierades de fyra koncepten till tre förslag på monteringsprocesser. Processerna balancerades, layouter utvecklades och simuleringsmodeller producerades för varje process. Varje förslag analyserades baserat på kostnad, prestanda, implementation,flexibilitet och arbetar-förhållande. Resultatet blev en stationär monteringsprocess och en 3Dsimulering gjordes för visualisering och förståelse. Den stationära monteringsprocessen har en kapacitet på 90 rotatorer per dag och reducerar behovet av montörer.Layouten för monteringsstationerna baseras på processens layout och har modifierats för ergonomiska aspekter. Inom monteringsstationerna så utvecklades layouten för att minimera antalet onödiga rörelser för montören. Testriggens design utvecklades genom att analysera de behov som fanns, skapa en kravspecifikation samt utvärdera och besluta om testprocedur, upplägg för testrigg och dess ingående komponenter. Testriggen uppfyller målsättningen som är att kunna mäta dynamiskt vridmoment, räkna partiklar för att säkerställa renhet i rotatorn och kunna utföra testningen självgående för att frigöra montören under testprogrammet.
325

High frequency CMUT for continuous monitoring of red blood cells aggregation

Younes, Khaled 06 1900 (has links)
No description available.
326

Vývoj testovacího přípravku délkového snímače / Development of the testing device for length measurement

Kirchner, Jan January 2018 (has links)
Aim of this thesis is a verification of possibility to measure displacement in small range using sensor based on the principle of strain gauge. For testing purspose, an evaluating unit was designed, made and assembled. This unit contains analog/digital converter, LCD and it has an abbility to move measuring plane using stepper motor. Next part of this thesis is about testing new prototype of strain gauge sensor, including evaluation of results of measuring. The performed measurements were measuring linearity, time stability and repeatability. Based on the results of the measurements, the possibility of using this type of length measuring device was confirmed for further development.
327

Vstupní díl UHF přijímače s velmi nízkou spotřebou / Tuner for UHF Receiver with Low Power Consuption

Kaštánek, Martin January 2008 (has links)
The purpose of this work was to make a proposal for input parts of receiver for band 430 to 440 MHz. A model of chosen semiconductor triode BFP540 was created in simulation software. Possibilities how to decrease consumption of this semiconductor triode, keeping the profit, were investigated through the simulation.In compromise consumption, keeping the profit of the amplifier - an optimal operating point for this semiconductor triode UCE = 1,2 V and IC = 2 mA was found. It was tested through the testing wiring with noise microstrips conformity. Ascertained knowledge was used for construction of tuner for UHF receiver. An operating point of input amplifier of UHF receiver was owing to power supply amplifier forced for bigger effectiveness to UCE = 2,65 V and IC = 2,0 mA. Suppression of mirror frequency is provided with Helix filter of the third order, because of intermediate frequency 10,7 MHz. Mixing on intermediate frequency is made again by semiconductor triode BFP540. Selectivity of receiver is provided with intermediate frequency crystal filter 10,7 MHz with bandwidth 15 kHz. Designed input part enables reception of SSB, FM and digital types of modulation.Bandwidth intermediate frequency exit is adapted to this request To receive particular modulation , it is necessary to complete intermediate frequency signal way with appropriate intermediate frequency filter.
328

Nízkošumový zesilovač pro pásmo S / Low-noise S-band amplifier

Potěšil, Dušan January 2008 (has links)
This work deals with design, simulation and realisation of a receiving systém of an S-band front end for satellite communication. The first part of the project is designed the low noise amplifier (LNA) with high associated gain. The basic point of the design is choice of the active device. In the present time are available the ultra low noise transistors based on the GaAs with high mobility electron. The two-stage LNA has been designed with Agilent ATF-55143. It is pseudomorphic HEMTs ,which work in an enhancement mode.These transistor do not require a negative bias voltage and have extremely good typical noise figure. The design includes an interdigital tuned band pass filter between stages. The second part of the project is search another way design circuit. There are designed two LNA with paralel coupled line filter. The first has been applied on a PTFE substrate Duroid 5880 with relative permitivity 2,2 and tg d = 0,009. The substrate FR-4 (r = 4.34) with the thickness 0.06” was used for the realization.
329

Realizace úzce směrového akustického měniče / Implementation narrowly directed beeper

Hladký, David January 2016 (has links)
The present final thesis discusses the transmission of a narrowly directional parametric sound beam through an amplitude-modulated ultrasonic wave, utilizing the effect of auto-demodulation in a nonlinear medium and ensuring the subsequent processing of the input signal for the parametric sound transmitter. Emphasis is placed on the mathematical tools that relate to parametric sound transmission in a nonlinear medium. The basic part of the thesis describes a parametric speaker and the associated amplitude modulation techniques, which constitute a major prerequisite for the processing of the transmitted signal. In the following section, the author then analyzes the computational intensity of these techniques, considering applicable hardware approaches. Finally, the fabrication and practical use of the proposed solution are discussed, including the measurement of typical parameters such as the spatial radiation characteristics, total harmonic distortion, and transmission channel bandwidth.
330

Ultrazvukový směrový reproduktor / Ultrasonic Directional Speaker

Sedlák, Jiří January 2017 (has links)
The master´s thesis deals with theoretical research and practical application of the principle of spreading acoustic waves through nonlinear medium. The theoretical part describes five different types of amplitude modulation and their mathematic representation, which were verified by the program Matlab. Next, the impedance characteristic of ultrasound PZT transducer was measured and the design of PWM modulator and class D amplifier was described. The practical part of the master´s thesis contains the realization of the parametric loudspeaker assembled from the class D amplifier and the PWM modulator. In conclusion, the designed parametric loudspeaker was measured and the individual types of amplitude modulation were compared with respect to the total harmonic distortion of transmitted useful signal.

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