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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.
631

Selected Synthetic Studies of NLO pi-Bridges and Thermally Stable Monomers

Fauley, Stacey Marie 17 October 2002 (has links)
No description available.
632

RF Methods to Increase Deuteron Polarization in HD Targets and NMR Spin-Polarization Analysis at LEGS

Bade, Christopher M. 14 April 2006 (has links)
No description available.
633

Kostnadseffektiv enhet för fjärrövervakning av inbyggda system

Byström, Henrik, Rickardsson, Filip January 2013 (has links)
Företag kan ha produktionsanläggningar på ett antal olika platser runt om i världen. Den industriella utrustningen som används i anläggningarna innehåller ofta någon form av inbyggt system som kräver underhåll eller övervakning vid jämna mellanrum. Utrustningen kan vara tekniskt avancerad och därför måste underhållet skötas av en servicetekniker. Mindre leverantörer av industriella utrustningar har inte alltid möjlighet att ha serviceorganisationer i varje land då detta innebär en extra kostnad. Det hade därför varit fördelaktigt med ett kompletterande kommunikationssystem som fungerar som en mellanhand mellan servicetekniker och målsystem som kan befinna sig på skilda platser.Kommunikationssystemet som tagits fram i detta projekt fungerar som en typ av fjärrövervakning där det är möjligt att utföra fjärravläsning samt ändra inställningar på distans. Syftet med examensarbetet är därför att utveckla en enkel och kostnadseffektiv enhet avsedd för fjärrövervakning av utrustningar innehållande inbyggda system.Examensarbetet resulterade i en kostnadseffektiv prototyp av en övervakningsenhet, baserad på enkortsdatorn Raspberry Pi, som kan kopplas in till ett målsystem när service behövs. I projektet testades kommunikationssystemet mot ett målsystem baserat på enkortsdatorn Arduino Uno. Övervakningsenheten har möjlighet att kommunicera med målsystemet via tre olika sätt: RS-232, JTAG samt kommunikation via GPIO-pinnar. Dessa kommunikationssätt kan användas till olika ändamål då kommunikationssätten är användbara för olika tillämpningar och kan därmed möjliggöra implementering av många olika funktioner. Kommunikationssätten är dessutom välanvända och passar till många olika målsystem. Servicetekniker har två tillgängliga användargränssnitt för att interagera med övervakningsenheten. Det primära användargränssnittet är ett webbgränssnitt där utdata från målsystemet kan övervakas samt att det finns möjlighet att ställa in olika inställningar. Det andra användargränssnittet består av fjärrstyrning av övervakningsenheten där funktioner finns för att utföra felsökning (eng. debugging) samt möjlighet att ladda in ett nytt program på målsystemet. / Companies can have production plants in a variety of locations around the world. The industrial equipment used in facilities often includes some form of built-in systems which require maintenance or monitoring at regular intervals. The equipment can be technologically advanced and therefore maintenance must be performed by a service technician. Smaller suppliers of industrial equipment are not always able to have service departments in each country, which often means an additional cost. It would therefore be advantageous with an additional communication system that acts as an intermediary between the service technician and the target system that can be located in different places.The communication system developed in this project acts as a kind of remote monitoring where it is possible to perform remote reading, and change different settings remotely. The purpose of this study is therefore to develop a simple and cost effective device designed for remote monitoring of equipment containing embedded systems.The study resulted in a cost-effective prototype, based on the single board computer Raspberry Pi, of a monitoring device that can be connected to a target system when service is needed. The communication system was tested throughout the project on a target system based on the single board computer Arduino Uno. The monitoring unit is able to communicate with the target system via three different ways: RS-232, JTAG and communication via GPIO-pins. These communication methods can be used for different purposes as these communication methods are useful for various applications and can thus enable implementation of many different functions. The communication methods are also widely used and suitable for many different target systems. Service technicians have two available user interfaces for interacting with the monitoring unit. The primary user interface is a web interface where the output of the target system can be monitored and that there is the possibility to set different settings. The second interface is remote controlling of the monitoring device which has functions to perform debugging and the ability to flash a new program into the target system.
634

The Effects of Vibronic coupling on the Photophysics of pi-conjugated oligomers and polymers

Yamagata, Hajime January 2013 (has links)
A theoretical model describing photophysics of π-conjugated aggregates, such as molecular crystals and polymer thin films, is developed. A Holstein-like Hamiltonian expressed with a multi-particle basis set is used to evaluate absorption and photoluminescence (PL) spectra. An analysis with line strength ratio proves to be a powerful diagnostic tool to obtain additional spectral signatures with which to distinguish H- vs. J-aggregation. For the H-aggregates absorption peak ratio, A0-0/A0-1, diminishes as the excitonic coupling increases. Also the PL peak ratio, I0-0/I0-1, is zero at T=0K with no disorder and the value increases as temperature and disorder increase. By contrast the J-aggregates show the opposite trends. Furthermore we will show the PL peak ratio provides a direct measurement of the exciton coherence length for a linear J-aggregate and could be expressed as I0-0/I0-1 = Ncoh/l2. We will also show that it is inversely proportional to square root of temperature (T-1/2). Applying our theory to the herringbone style oligoacene molecular crystals, we show the lowest singlet exciton states are highly influenced by charge transfer (CT) states and the well known energetic gap in two polarized absorption spectra, so called Davydov Splitting (DS), is a product of the interaction. We have successfully reproduced the DS for all three oligoacenes without any free parameters. Inspired by the CT contribution in oligoacene crystals, we further develop Wannier-Mott exciton model and apply to disorder-free polydiacetylene (PDA) quantum wires, which have been shown to be extremely emissive. We will show the quantum wire is a J-aggregate and we once again derive the peak ratio and the coherence size relation, I0-0/I0-1 = kNcoh/l2, where k is a prefactor close to unity. Typical photophysical properties of polymer p-stacks such as those occurring in P3HT films are well explained by the simple linear H-aggregate model. However several groups have started seeing more J-like behaviors amongst “improved” (less disordered) polymer films such as increased values of A0-0/A0-1 and I0-0/I0-1 and higher radiative rates. With the new perception of a single polymer chain being a J-aggregate, we apply our new theory to p-stack of polymer chains. We call this HJ-aggregate model since the interchain interaction induces H-aggregation. In the study we show a competition between intrachain and interchain interactions that leads to unique photophysical features. The new model is capable of explaining a wide range of polymer systems and most importantly the theory uncovers the mechanism of the improved polymer films; reducing disorder urges increasing intrachain reactions within each chain, thus enhancing more J-like spectral features. / Chemistry
635

Selected Topics in Analysis in Metric Measure Spaces

Capolli, Marco 02 February 2021 (has links)
The thesis is composed by three sections, each devoted to the study of a specific problem in the setting of PI spaces. The problem analyzed are: a C^m Lusin approximation result for horizontal curves in the Heisenberg group, a limit result in the spirit of Burgain-Brezis-Mironescu for Orlicz-Sobolev spaces in Carnot groups and the differentiability of Lipschitz functions in Laakso spaces.
636

Från videoinspelning till animatronisk fisk med AI : Automatiserad nyhetsbrevssammanfattning och uppspelning / From video recording to animatronic fish with AI : Automated newsletter summarization and playback

Öborn Sandström, Johan, Noah, Däckfors January 2024 (has links)
Olika former av nyhetsbrev har funnits i århundraden. På Redpill Linpros kontor i Karlstadpubliceras veckoliga nyhetsbrev i form av videoinspelningar. För att de anställda påföretaget snabbt ska kunna ta del av innehållet i dessa videoinspelningar är detta projektssyfte och mål att skapa en automatiserad process som sammanfattar dessa veckoliganyhetsbrev. Sammanfattningen ska sedan kunna tas del av genom att spela upp dennapå en animatronisk fisk gjord av plast med inbyggda högtalare. Projektet implementerasmed begränsad hårdvara och ingen data delas med tredje part. För att uppnå detta målundersöks och implementeras olika verktyg som använder sig av artificiell intelligenssamt så modifieras den animatroniska fisken. Resultatet av arbetet är en modulär processsom upptäcker publicering, transkriberar, sammanfattar och läser upp sammanfattningenav veckoliga nyhetsbrev. Uppläsningen kan sedan spelas upp på den förutnämndaanimatroniska fisken med ett enkelt knapptryck. / Various predecessors of newsletters have been around for centuries. At Redpill Linpro’soffice in Karlstad, weekly newsletters are published in the form of video recordings. Inorder for the employees to be able to quickly take part of the content of these videorecordings, the purpose and goal of this project is to create an automated process thatsummarizes these weekly newsletters. The summary is then shared by the possibility ofplaying it on an animatronic fish made of plastic with built-in speakers. The project isimplemented with limited hardware and no data is shared with third parties. To achievethis goal, various tools that use artificial intelligence are researched and implemented,and the animatronic fish is modified. The result of the work is a modular process thatdetects publication, transcribes, summarizes and reads the summary of weekly newsletters.The reading can then be played back on the aforementioned animatronic fish witha simple push of a button.
637

Modeling and Implementation of Controller for Switched Reluctance Motor With Ac Small Signal Model

Wang, Xiaoyan 19 October 2001 (has links)
As traditional control schemes, open-loop Hysteresis and closed-loop pulse-width-modulation (PWM) have been used for the switched reluctance motor (SRM) current controller. The Hysteresis controller induces large unpleasant audible noises because it needs to vary the switching frequency to maintain constant Hysteresis current band. In contract, the PWM controller is very quiet but difficult to design proper gains and control bandwidth due to the nonlinear nature of the SRM. In this thesis, the ac small signal modeling technique is proposed for linearization of the SRM model such that a conventional PI controller can be designed accordingly for the PWM current controller. With the linearized SRM model, the duty-cycle to output transfer function can be derived, and the controller can be designed with sufficient stability margins. The proposed PWM controller has been simulated to compare the performance against the conventional Hysteresis controller based system. It was found that through the frequency spectrum analysis, the noise spectra in audible range disappeared with the fixed switching frequency PWM controller, but was pronounced with the conventional Hysteresis controller. A hardware prototype is then implemented with digital signal processor to verify the quiet nature of the PWM controller when running at 20 kHz switching frequency. The experimental results also indicate a stable current loop operation. / Master of Science
638

Mitigating delay and coupling effects in a high-speed PMSM drive using an optimal multivariable control approach

Tasnim, Kazi Nishat 10 May 2024 (has links) (PDF)
In this thesis, an optimal multivariable current control method is presented for the highspeed permanent magnet synchronous motor (HS-PMSM). The HS-PMSMs have growing applications in the industry. One of their major challenges is the low switching to fundamental frequency ratio (SFR). At high speed and low SFR, the control time delays including the digital, the PWM, and sensor delays become more pronounced and lead to oscillations and even instabilities. A well-known method for delay compensation is to advance the phase angle of control input for a known amount. In practice, the exact delay is unknown, and mismatch in the compensating angle causes deteriorating effect on the system. In the proposed method, the digital and PWM delays are modelled and integrated with an optimal multivariable controller. This method improves the stability margin and achievable speed margin compared to the traditional phase advancing delay compensation (PADC) method. Combining the proposed delay modeling and the PADC method further improves the response, as the uncertain sensor delays can be compensated greatly. Besides the delay, the cross-coupling between ���� axis affects the dynamic performance of the machine. The proposed multivariable approach considers and directly addresses the coupling. Dynamic performance of the PMSM with the proposed method is thoroughly compared with the conventional delay compensation method. The proposed method is validated through extensive simulation studies on a 2 kW high-speed machine.
639

En Studie av Pi Patel’s Copingstrategier i Life of Pi : Religion och coping

Hendi, Haya January 2024 (has links)
This study examines how religion is portrayed in the movie Life of Pi (2012) and how the main character Pi Patel uses his faith to deal with and survive various challenges. People deal with challenges in different ways, and this study focuses on the combination of divine and human resources in the coping process. The aim is to explore Pi's use of religion through a content analysis of the movie, with particular focus on coping theory and the functional definition of religion as a theoretical framework. The analysis shows that Pi faces several difficulties on the lifeboat, such as an aggressive tiger, lack of food and water, as well as feelings of loneliness and hopelessness. To master these challenges, Pi combines emotional and practical coping strategies, where religion plays a central role. Religion gives him not only support and guidance but also motivation and companionship. The religion also contributes to his development as a person and causes him to embrace three religions. Through this study, we can better understand how religion can function as a coping mechanism and contribute to people's survival and development in extreme situations.
640

Piano Hero : Interactive musical learning

Ahlzén, Anton, Holma, Ville, Segerberg, Adam, Varahram, Sam, Wiig, Marcus January 2024 (has links)
Learning to play the piano usually involves learning to read sheet music and many hours of prac- tice, which can be seen as a tough task for beginners. This project presents an innovative ap- proach to piano learning by integrating a Raspberry Pi, Arduino, and LED lights with a Casio CTK-550 keyboard. This system interprets MusicXML files and visually guides users by lighting up the keys they need to press in the correct order, providing a more intuitive and engaging learn- ing experience. Additionally, it has a playback mode that makes the piano play the chosen song while illuminating the keys played. This allows the user to hear the song being played correctly before using the interactive mode to play the entire song themselves. These modifications to the piano aim to simplify the learning process and ease in new piano players by removing the big initial barrier of understanding sheet music. The project practices sustainability by reusing components from old projects and also follows several UN Sustainable Development Goals. After a few iter- ations, there was a product able to fulfill the goals set in advance. Future improvements could include improved lighting precision, additional learning modes, and more user-friendly file transfer possibilities.

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