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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.
101

Flexible Sector Coupling (FSC) of Electrical and Thermal Sectors via Thermal Energy Storage (TES) : A Case Study on Oskarshamn Energi

Calvo García, Raúl, Marín Arcos, Jose María January 2023 (has links)
The integration of distributed energy sources and systems is of high relevance for the transition towards a more sustainable energy system. Taking into consideration the  amount of emissions produced by the heating sector, which account for at least half of the energy demand in buildings, district heating systems have the potential to play a key role in the transition, by enabling the integration of various energy sources and provide flexible energy services to the grid. The objective of this research is to evaluate the potential for flexible sector coupling between the electrical and heating sectors, utilizing thermal energy storage alongside various heat generation units, including heat pumps and a combined heat and power (CHP) unit. To examine this concept, we used a district heating facility located in Oskarshamn, Sweden, as our case study. At present, the production mix at this facility comprises various production units- that utilize mainly biomass as their fuel source, including wood pellets, wood chips, and occasionally, bio-oil. Extensive research was conducted to review the existing literature and gain a comprehensive understanding of the technologies and concepts associated with FSC. This thorough examination allowed for a comprehensive overview of the current state-of-the-art in FSC. As the main contributions of this work, two numerical models respectively for production and dispatch optimization were developed and simulated complementary, concerning the thermal and electrical system of the studied plant. A dispatch model was developed with the aim of analyzing the operating behaviour of the system, identifying the available energy sources and optimizing their hourly dispatch. Subsequently, utilizing the open-access tool for capacity and investment optimization (OSeMOSYS), various scenarios were examined to evaluate the potential of thermal energy storage (TES), where a water tank was found to be the most cost-effective solution, and heat pump integration in enhancing the plant performance and providing flexibility. The study was divided into two distinct time periods. The first period focused solely on hourly dispatch optimization until 2035. In the second period, the analysis extended to include investment optimization, followed by the subsequent dispatch optimization until 2050, hence, using both tools. To effectively compare and assess the different scenarios, several key performance indicators (KPIs) were chosen, including the levelized cost of energy (LCOE), capital expenditure (CAPEX), generation costs, and emissions. These scenarios were designed to account for variations in crucial variables such as electricity prices, the plant’s self-consumption potential, and the capital cost of storage. By considering the aforementioned factors, a comprehensive analysis was conducted to determine the optimal approach for maximizing performance and cost-effectiveness. It is important to mention that the electrical self-consumption within the plant was considered as one of the potential improvements. While the potential for electrical self-consumption was mainly studied on a shorter-term, the variability in the capital cost of the TES system was better considered on the long-term investment analysis. From the different simulations, the cases where self-consumption is included result in smaller operating costs, as producing electricity via the CHP unit of the plant is cheaper on average than the prices offered by the local distribution company. The obtained capacities for TES and the heat pump vary among the studied scenarios. Higher electricity prices favor investments in alternative fuel boilers like wood chips or wood pellets, while lower electricity prices result in increased TES capacities and higher heat pump production. The capital cost of storage also determines the capacity chosen for the storage water tank, sometimes investing a bit more to gain efficiency and reduce operational costs. Throughout the project, various sustainability aspects have been addressed. These encompass environmental responsibilities, with a focus on reducing CO2 emissions, enhancing social equity by implementing a more efficient heating system within the municipality, and assessing the economic viability of these initiatives. In conclusion, the study provides evidence and showcases the viability of implementing FSC in Oskarshamn’s power plant, as results from the different scenarios commonly show that FSC could bring down the total costs, as well as the amount of CO2 emissions on a long-term basis. Based on the findings, additional recommendations are proposed to optimize the plant’s performance and leverage the potential of this innovative approach. The proposed recommendations include increasing the time resolution in the model simulations to improve result accuracy and exploring different scenarios, which may involve considering various electricity or fuel price predictions, among other factors. / Integreringen av distribuerade energikällor och energisystem är av stor betydelse för övergången till ett mer hållbart energisystem. Med hänsyn till det utsläpp från värmesektorn, som står för minst hälften av energibehovet i byggnader, har fjärrvärmesystem potential att spela en nyckelroll i omställningen genom att möjliggöra integrering av olika energikällor och tillhandahålla flexibla energitjänster till nätet. Syftet med denna forskning är att utvärdera Potentialen för flexibel sektorkoppling (FSC) mellan el- och värmesektorerna, med hjälp av termisk energilagring tillsammans med olika värmeproduktionsenheter, inklusive värmepumpar och en kombinerad kraftvärmeproduktion (CHP). För att undersöka detta koncept, använde vi en fjärrvärmeanläggning i Oskarshamn, Sverige, som vår fallstudie. För tillfället består produktionsmixen vid denna anläggning av olika produktionsenheter som huvudsakligen använder biomassa som bränslekälla, inklusive träpellets, träflis och ibland bioolja. Omfattande forskning genomfördes för att granska den befintliga litteratur och få en heltäckande förståelse för de tekniker och koncept som är förknippade med FSC. Denna grundliga undersökning möjliggjorde en omfattande översikt av det aktuella kunskapsläget inom FSC. Som de viktigaste bidragen i detta arbete utvecklades och simulerades två numeriska modeller för produktions- respektive leveransoptimering, som berör det termiska och elektriska systemet i den studerade anläggningen. En fördelningsmodell utvecklades i syfte att analysera systemets driftsbeteende, identifiera tillgängliga energikällor och optimera deras fördelning per timme. Med hjälp av det verktyget med öppna tillgång (open-aceess) för kapacitets- och investeringsoptimering (OSeMOSYS) undersöktes därefter olika scenarier för att utvärdera potentialen för termisk energilagring (TES), där en vattentank visade sig vara den mest kostnadseffektiva lösningen, och integration av värmepumpar för att förbättra anläggningens prestanda och ge flexibilitet. Studien var uppdelad i två olika tidsperioder. Den första perioden fokuserade enbart på optimering av timfördelning fram till 2035. Under den andra perioden utvidgades analysen till att omfatta investeringsoptimering, följt av efterföljande optimering av driften fram till 2050, vilket innebär att båda verktygen användes. För att effektivt kunna jämföra och bedöma de olika scenarierna valdes flera viktiga nyckelprestandaindikatorer (KPI:er), inklusive den nivellerade energikostnaden (LCOE), kapitalinvesteringar (CAPEX), produktionskostnader och CO2 utsläpp. Dessa scenarier utformades för att ta hänsyn till variationer i viktiga variabler som elpriser, anläggningens självkonsumtionspotential och kapitalkostnaden för lagring. Med hänsyn till de ovan nämnda faktorerna genomfördes en omfattande analys för att fastställa den optimala metoden för att maximera prestanda och kostnadseffektivitet. Det är viktigt att nämna att den elektriska självförbrukningen inom anläggningen betraktades som en av de potentiella förbättringarna. Medan potentialen för elektrisk självförbrukning främst studerades på kortare sikt, beaktades variationen i kapitalkostnaden för TES-systemet bättre i den långsiktiga investeringsanalysen. De olika simuleringarna visar att de fall där självförbrukning ingår resulterar i lägre driftskostnader, eftersom elproduktionen via kraftvärmeverket i genomsnitt är billigare än de priser som erbjuds av det lokala distributionsbolaget. De erhållna kapaciteterna för TES och värmepumpen varierar mellan de studerade scenarierna. Högre elpriser gynnar investeringar i alternativa bränslepannor som flis eller träpellets, medan lägre elpriser resulterar i ökad TES-kapacitet och högre värmepumpsproduktion. Kapitalkostnaden för lagring avgör också vilken kapacitet som väljs för vattentanken (some en TES), ibland investerar man lite mer för att öka effektiviteten och minska driftskostnaderna. Under hela projektet har olika hållbarhetsaspekter beaktats. Dessa omfattar miljöansvar, med fokus på att minska CO2-utsläppen, öka den sociala rättvisan genom att införa ett mer effektivt värmesystem inom kommunen, och bedöma den ekonomiska bärkraften i dessa initiativ. Sammanfattningsvis visar studien att det är möjligt att implementera FSC i Oskarshamns kraftverk, eftersom resultaten från de olika scenarierna visar att FSC kan sänka de totala kostnaderna samt mängden CO2-utsläpp på lång sikt. Baserat på resultaten föreslås ytterligare rekommendationer för att optimera anläggningens prestanda och utnyttja potentialen i denna innovativa metod. De föreslagna rekommendationerna inkluderar att öka tidsupplösningen i modellsimuleringarna för att förbättra resultatens noggrannhet och utforska olika scenarier, vilket bland annat kan innebära att man överväger olika el- eller bränsleprisprognoser.
102

Entwicklung eines Befestigungssystems für Photovoltaikmodule / Development of a mounting system for PV-Modules

Tautenhahn, Lutz 02 June 2015 (has links) (PDF)
Der derzeitige technische Fortschritt stützt sich maßgeblich auf die Nutzung von elektrischem Strom. Der Anteil der Stromerzeugung aus Sonnenlicht hat mittlerweile in Deutschland den der Wasserkraft überschritten, der 1990 noch der größte regenerative Energielieferant war. Die Technologie der Photovoltaik (PV) wandelt die hochenergetische Strahlung der Sonne in elektrischen Strom um und nutzt dabei häufig Glasplatten als tragende Struktur. Der Hauptanspruch dieser Arbeit liegt in der Entwicklung und Untersuchung eines Befestigungssystems mit einer höher- oder hochmoduligen Klebverbindung zum gläsernen PV-Modul sowie einer möglichst universell einsetzbaren Fügeverbindung zur Unterkonstrukion. Die systematische Enwicklung der Fügeverbindung zum PV-Modul basiert auf dem Ansatz eines flexiblen, stützenden \\hbox{Ringes} für das Fügeelement (Halter), um die durch eine mechanische Belastung der Module induzierten Zugspannungen im Glas über der Fügeelementkante zu reduzieren. Eine neuartige, kombinierte Klammer-Keil-Verbindung sichert die Befestigung auf einer von ihr unabhängigen Unterkonstruktion sowohl quer als auch längs zur Schienenrichtung. Experimentelle Arbeiten charakterisieren die eingesetzte Klebverbindung unter verschiedenen Beanspruchungsszenarien, um sowohl konstruktions- als auch klebstoffbedingte Möglichkeiten und Grenzen der Fügeverbindung für die vorliegende Anwendung zu identifizieren. Die Untersuchungen weisen zudem geeignete Vorbehandlungsmaßnahmen der Aluminiumoberflächen aus. Sowohl numerische Simulationen als auch die neuartig eingesetzte Nahbereichsphotogrammetrie bestätigen in Bauteiluntersuchungen die vorteilige Wirkung des flexiblen, höhermodulig geklebten Ringes. Die vorliegende Arbeit setzt sich hierbei auch kritisch mit unterschiedlichen Einflüssen auf die Ergebnisse auseinander, die einerseits durch verschiedene Prüfstände hervorgerufen werden können und andererseits auch den verwendeten Methoden zugrunde liegen. / Today much of technical advances are due to the usage of electricity. The contribution of solar power to the production of electricity in Germany currently surpasses water powered electricity which was in 1990 the almost exclusive renewable energy source. The technology of photovoltaic systems based on high-powered sun radiation, often utilizes glass plates as a supporting structure. This dissertation primarily focuses on the research and development of a mounting system with a higher or high modulus adhesively bonded joint to the PV-module as well as an all-purpose connection to the substructure. The systematical development process of the connection to the PV-module is based on the approach of a flexible supporting ring-shaped mounting element. This reduces the tension within the glass surface at the edge of the mounting element when mechanically loading the PV-module. A novel connection using a clamp-wedge combination ensures the ability to mount the PV-module horizontally or vertically to the rail substructure. Through the development process, the bonded joint is exposed to various scenarios where the construction as well as the adhesive possibilities and limitations under each scenario are analyzed. Research outcomes yield recommendations for appropriate pre-treatment of the aluminum surfaces. Numerical simulations as well as the novel use of the near-field photogrammetry method confirmed beneficial action of the flexible ring-shaped mounting element within assembly testing of large glass specimens. This dissertation discusses how different variables can have a considerable effect on results when introduced through the testing device and through monitoring methods.
103

EXPRESSIVE WRITING: QUALITY OF LIFE, PRONOUNS AND WORKING MEMORY - A PILOT STUDY

Lindgren, Helén January 2018 (has links)
For 30 years researchers have studied Expressive Writing (EW) - writing emotionally about a trauma 3-5 times for 15-30 minutes, while controls (CW) objectively write about, most often, time management. Previous research has documented associations, in the trauma condition, between flexible use of pronouns and physical health, or between trauma writing and improvement of working memory (WM). The main aim of the current study was to see if there is a relation between flexible use of first-person pronoun singular (“I”) in EW and improved results on WM test, as well as on quality of life and self-reported illness. In an Internet study participants were recruited through convenience and snowball sampling and randomly divided on conditions. The final sample consisted of 10 participants each in EW and CW: 13 women, 6 men and 1 non-binary, 21-69 years, most of them well educated. Outcome measures were WM test (Automated version of Operation Span Task; AOSPAN), self-reported quality of life (Brunnsviken Brief Quality of Life; BBQ) and self-reported illness (days of symptoms and restricted activities). JASP was used for the statistics. A measure of flexible use of the Swedish pronoun “jag” (“I”) was tested and found to associate with significant improvements in AOSPAN results only; unexpectedly within the whole sample. On condition one significant result was found: EW improved their quality of life. The increase in AOSPAN results is discussed, as well as writing instructions and baseline assessments. The small sample with self-reported health measures and online WM test limited the study. Replications of the results are needed. / I 30 år har forskare studerat Expressivt skrivande (EW) - att skriva känslomässigt om ett trauma 3-5 gånger à 15-30 minuter. Kontrollbetingelsen (CW) har ofta bestått av att objektivt beskriva sin tidsanvändning. Tidigare forskning har i traumabetingelsen påvisat samband mellan en flexibel användning av pronomen och fysisk hälsa, eller mellan traumaskrivande och förbättrade resultat på test av arbetsminne (WM). Huvudsyftet med den föreliggande studien var att se om det finns ett samband mellan en flexibel användning i EW av pronomenet första person singular (”jag”) och förbättrade resultat på arbetsminnestest, samt på livskvalitet och självrapporterad ohälsa. Tio deltagare vardera deltog i experiment- respektive kontrollgruppen: 13 kvinnor, 6 män och 1 icke-binär, 21-69 år; de flesta välutbildade. Deltagarna rekryterades genom bekvämlighets- och snöbollsurval och fördelades slumpvis till betingelserna. En internetstudie genomfördes, med utfallsmåtten arbetsminnestest (Automated version of Operation Span Task; AOSPAN), självskattad livskvalitet (Brunnsviken Brief Quality of Life; BBQ), samt självskattad ohälsa (dagar med symptom respektive med begränsade aktiviteter). JASP användes för de statistiska analyserna. Ett mått för flexibel användning av det svenska pronomenet ”jag” testades och visade sig vara associerat med signifikanta förbättringar enbart av AOSPAN-resultatet, men förvånande nog inom hela urvalet. I övrigt hittades endast en skillnad mellan betingelserna, nämligen att experimentgruppen signifikant förbättrade sin självskattade livskvalitet. Ökningen av AOSPAN-resultaten diskuteras, liksom skrivinstruktioner och baslinjeskattningar. Studien begränsades av ett litet urval, självskattade hälsomått och nätbaserat arbetsminnestest. Replikationer av resultaten är nödvändiga.
104

Entwicklung eines Befestigungssystems für Photovoltaikmodule

Tautenhahn, Lutz 30 January 2015 (has links)
Der derzeitige technische Fortschritt stützt sich maßgeblich auf die Nutzung von elektrischem Strom. Der Anteil der Stromerzeugung aus Sonnenlicht hat mittlerweile in Deutschland den der Wasserkraft überschritten, der 1990 noch der größte regenerative Energielieferant war. Die Technologie der Photovoltaik (PV) wandelt die hochenergetische Strahlung der Sonne in elektrischen Strom um und nutzt dabei häufig Glasplatten als tragende Struktur. Der Hauptanspruch dieser Arbeit liegt in der Entwicklung und Untersuchung eines Befestigungssystems mit einer höher- oder hochmoduligen Klebverbindung zum gläsernen PV-Modul sowie einer möglichst universell einsetzbaren Fügeverbindung zur Unterkonstrukion. Die systematische Enwicklung der Fügeverbindung zum PV-Modul basiert auf dem Ansatz eines flexiblen, stützenden \\hbox{Ringes} für das Fügeelement (Halter), um die durch eine mechanische Belastung der Module induzierten Zugspannungen im Glas über der Fügeelementkante zu reduzieren. Eine neuartige, kombinierte Klammer-Keil-Verbindung sichert die Befestigung auf einer von ihr unabhängigen Unterkonstruktion sowohl quer als auch längs zur Schienenrichtung. Experimentelle Arbeiten charakterisieren die eingesetzte Klebverbindung unter verschiedenen Beanspruchungsszenarien, um sowohl konstruktions- als auch klebstoffbedingte Möglichkeiten und Grenzen der Fügeverbindung für die vorliegende Anwendung zu identifizieren. Die Untersuchungen weisen zudem geeignete Vorbehandlungsmaßnahmen der Aluminiumoberflächen aus. Sowohl numerische Simulationen als auch die neuartig eingesetzte Nahbereichsphotogrammetrie bestätigen in Bauteiluntersuchungen die vorteilige Wirkung des flexiblen, höhermodulig geklebten Ringes. Die vorliegende Arbeit setzt sich hierbei auch kritisch mit unterschiedlichen Einflüssen auf die Ergebnisse auseinander, die einerseits durch verschiedene Prüfstände hervorgerufen werden können und andererseits auch den verwendeten Methoden zugrunde liegen. / Today much of technical advances are due to the usage of electricity. The contribution of solar power to the production of electricity in Germany currently surpasses water powered electricity which was in 1990 the almost exclusive renewable energy source. The technology of photovoltaic systems based on high-powered sun radiation, often utilizes glass plates as a supporting structure. This dissertation primarily focuses on the research and development of a mounting system with a higher or high modulus adhesively bonded joint to the PV-module as well as an all-purpose connection to the substructure. The systematical development process of the connection to the PV-module is based on the approach of a flexible supporting ring-shaped mounting element. This reduces the tension within the glass surface at the edge of the mounting element when mechanically loading the PV-module. A novel connection using a clamp-wedge combination ensures the ability to mount the PV-module horizontally or vertically to the rail substructure. Through the development process, the bonded joint is exposed to various scenarios where the construction as well as the adhesive possibilities and limitations under each scenario are analyzed. Research outcomes yield recommendations for appropriate pre-treatment of the aluminum surfaces. Numerical simulations as well as the novel use of the near-field photogrammetry method confirmed beneficial action of the flexible ring-shaped mounting element within assembly testing of large glass specimens. This dissertation discusses how different variables can have a considerable effect on results when introduced through the testing device and through monitoring methods.
105

Kris i besöksnäringen? : En turismvetenskaplig studie om Värmländska småföretagares agerande och stöd under COVID-19

Kron, Paulina, Hallberg, Felicia January 2021 (has links)
In this study, crisis management has been studied primarily from the perspective of small business owners and lifestyle entrepreneurs. Over time, a need was also discovered to interview and study the relationship of public support organizationswith small businesses in crisis contexts. This is because in the theoretical research framework we experienced a lack of how private small businesses can act in a crisis. This is how our subject has been developed, and curiosity about practical crisis management versus theoretical crisis management has played a central role. Following the work, the niche of small entrepreneurs became in nature tourism, partly due to the fact that Värmland as a county has many entrepreneurs in this category. It is also inevitable that Värmland and the entrepreneurs here have had a strong international market before COVID-19 and therefore the interest has also been to study and analyze how they have acted and proceeded during the crisis. The question of adjustment is therefore very essential to study for future possible crises. To discern these similarities and differences, the private has been set against the regional and public, but also against each other. It has been conducted thanks to semi-structured interviews that highlight the same themes. The themes then follow a consistent structure for both method, empirical data and analysis, where it relates to the study's purpose and issues. Overall, the study has generated striking similarities and differences, but also a dimension in the exclusion of small business owners. The lastpart of the conclusion shows why it is still important to study the subject, as COVID-19 has affected the tourism industry in a very unique and global way, which has not previously been discernible. It highlights the importance of contributing to and continuing research in the future, where both public actors together with regional and private actors can find a way to deal with future crises together. / I denna studie har krishantering studerats utifrån framförallt småföretagares- och livsstilsföretagares perspektiv. Under tidens gång upptäcktes även ett behov av att intervjua och studera offentliga stödorganisationers förhållande till småföretagare i krissammanhang. Det på grund av att det i de teoretiska forskningsramarna upplevdes en brist för hur privata småföretagare kan agera vid kris. Det är genom den vägen ämnet har arbetats fram, och nyfikenheten kring praktisk krishantering versus teoretisk krishantering har spelat en central roll. Utefter arbetets gång kom nischen av småföretagare att bli inom naturturism, bland annat på grund av att Värmland som län innehar många företagare inom den kategorin. Det går heller inte att undkomma att Värmland och företagarna här har haft en stark internationell marknad innan COVID-19 och därför har intresset likaså varit att studera och analysera hur företagarna har agerat och gått tillväga under krisens gång för att ställa om. Omställningsfrågan är därför essentiell att studera för framtida eventuella kriser. För att skönja dessa likheter och skillnader har det privata ställts emot de regionala och offentliga, men även mot varandra. Det har utförts tack vare semistrukturerade intervjuer som lyft samma teman. Temana följer sedan en genomgående struktur för både metod, empiri och analys, där de förhåller sig till studiens syfte och frågeställningar. Studien har totalt sett genererat påvisande likheter och skillnader, men även en dimension i exkludering av småföretagare. I slutsatsens sista del framkommer det varför det är fortsatt viktigt att studera ämnet, eftersom COVID-19 har påverkat besöksnäringen på ett väldigt unikt och globalt sätt, som tidigare inte har kunnat skönjas. Det belyser vikten av att bidra med samt fortsätta forskning framöver där både offentliga aktörer tillsammans med regionala- och privata aktörer kan hitta ett sätt att tillsammans hantera kommande kriser / <p>C-uppsats </p>
106

Study of the Resistive Switching Mechanism in Novel Ultra-thin Organic-inorganic Dielectric-based RRAM through Electrical Observations / Undersökning av den Resistenta Omkopplingsmekanismen i Novel Ultra-tunna Organiska-oorganiska Dielectric-baserade RRAM genom Elektriska Observationer

Martinez Garcia, Alba Maria January 2021 (has links)
The promising role resistive random-access memory (RRAM) plays in the imminent reality of wearable electronics calls for a new, updated physical model of their operating mechanism. Their high applicability as the next-generation flexible non-volatile memory (NVM) devices has promoted the recent emergence of a novel ultra-thin (&lt; 5nm) organic/inorganic hybrid dielectric RRAM. A deep understanding of their resistive switching (RS) behavior is required to unlock their suitability in future electronics applications. However, the extremely reduced thicknesses bring about new challenges in terms of material characterization sample processing, while the RS observations through electrical characterization techniques lack uniformity in the key switching parameters, thus hindering the identification of any clear trends.  This work studies the RS mechanism in ultra-thin Al/Hf-hybrid/Ni RRAM devices through uniformity-improved electrical observations. First, the focus is to implement a ramped-pulse train method during the reset process to reduce the dispersion of the voltage and resistance fluctuations at different starting voltage amplitudes and pulse widths. After finding the optimal electrical programming conditions for reduced parameter dispersions, a temperature test was performed to study the contributions of the metal ions and oxygen vacancies (V2+) in the switching layer. Finally, a physical model describing the operating mechanism in flexible RRAM is proposed after the close observation and study of the processed devices. The model is based on the coexistence of a hetero-metallic portion composed of Al and Hf3Al2, and a V2+ portion connected to form the hybrid conducting filament (CF) and turning the device on. The CF forming processes emphasize the strong presence of these vacancies partaking in RS, as the temperature dependence results suggest the majority of their concentration to be generated during this step. Also, the different electrical potential, temperature, and concentration gradients influencing the V2+ migration during RS may explain some of the failure mechanisms in the rupture and the re-forming of the filament. Additionally, the possible presence of a thin Al-oxide layer in the Al/Hf-hybrid interface may give a reason for leaky on-states. A detailed physical model of the RS mechanism in next-generation flexible RRAMs is key to learn to unlock a range of emerging technologies fitted to today’s needs. / Den senaste introduktionen av ultratunn (&lt;5 nm) organisk-oorganisk hybrid dielektrisk RRAM som nästa generations icke-flyktiga minnesenheter kräver en djup förståelse för hybridskiktresistiv växling (RS). Den extremt reducerade tjockleken hindrar emellertid deras bearbetbarhet för materialkarakteriseringstekniker. Dessutom hindrar den dåliga enhetligheten i viktiga omkopplingsparametrar fortfarande i RRAM att alla trender kan definieras tydligt genom elektrisk karakterisering. Detta arbete använder elektrisk manipulation genom en RPS-metod (ramped-pulse series) för att förbättra spännings- och motståndsfluktuationerna i återställningsprocessen för ultratunna Al/Hf-hybrid/Ni-enheter vid olika spänningsamplitud, pulsbredd och temperaturförhållanden. Från de erhållna RPS-optimerade resultaten föreslås en ny och detaljerad fysisk modell som beskriver driftsmekanismen. Samexistensen i den ledande filamenten (CF) av en hybridmetalldel, sammansatt av Al och Hf3Al2, och en syrevakansdel bekräftas. Vår modell betonar vakansbidraget i RS, där majoriteten genereras under CF-formningsprocessen och deltar i olika grad i filamentbrottet för RPS och ingen RPS-bearbetade enheter via Joule-uppvärmning, drift och Fick-krafter. Dessutom förklaras kopplingsfelhändelser baserat på närvaron av ett Al2O3-lager i Al/Hf-hybridgränssnittet.
107

Shapeable microelectronics

Karnaushenko, Daniil 04 July 2016 (has links) (PDF)
This thesis addresses the development of materials, technologies and circuits applied for the fabrication of a new class of microelectronic devices that are relying on a three-dimensional shape variation namely shapeable microelectronics. Shapeable microelectronics has a far-reachable future in foreseeable applications that are dealing with arbitrarily shaped geometries, revolutionizing the field of neuronal implants and interfaces, mechanical prosthetics and regenerative medicine in general. Shapeable microelectronics can deterministically interface and stimulate delicate biological tissue mechanically or electrically. Applied in flexible and printable devices shapeable microelectronics can provide novel functionalities with unmatched mechanical and electrical performance. For the purpose of shapeable microelectronics, novel materials based on metallic multilayers, photopatternable organic and metal-organic polymers were synthesized. Achieved polymeric platform, being mechanically adaptable, provides possibility of a gentle automatic attachment and subsequent release of active micro-scale devices. Equipped with integrated electronic the platform provides an interface to the neural tissue, confining neural fibers and, if necessary, guiding the regeneration of the tissue with a minimal impact. The self-assembly capability of the platform enables the high yield manufacture of three-dimensionally shaped devices that are relying on geometry/stress dependent physical effects that are evolving in magnetic materials including magentostriction and shape anisotropy. Developed arrays of giant magnetoimpedance sensors and cuff implants provide a possibility to address physiological processes locally or distantly via magnetic and electric fields that are generated deep inside the organism, providing unique real time health monitoring capabilities. Fabricated on a large scale shapeable magnetosensory systems and nanostructured materials demonstrate outstanding mechanical and electrical performance. The novel, shapeable form of electronics can revolutionize the field of mechanical prosthetics, wearable devices, medical aids and commercial devices by adding novel sensory functionalities, increasing their capabilities, reducing size and power consumption.
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Shapeable microelectronics

Karnaushenko, Daniil 08 June 2016 (has links)
This thesis addresses the development of materials, technologies and circuits applied for the fabrication of a new class of microelectronic devices that are relying on a three-dimensional shape variation namely shapeable microelectronics. Shapeable microelectronics has a far-reachable future in foreseeable applications that are dealing with arbitrarily shaped geometries, revolutionizing the field of neuronal implants and interfaces, mechanical prosthetics and regenerative medicine in general. Shapeable microelectronics can deterministically interface and stimulate delicate biological tissue mechanically or electrically. Applied in flexible and printable devices shapeable microelectronics can provide novel functionalities with unmatched mechanical and electrical performance. For the purpose of shapeable microelectronics, novel materials based on metallic multilayers, photopatternable organic and metal-organic polymers were synthesized. Achieved polymeric platform, being mechanically adaptable, provides possibility of a gentle automatic attachment and subsequent release of active micro-scale devices. Equipped with integrated electronic the platform provides an interface to the neural tissue, confining neural fibers and, if necessary, guiding the regeneration of the tissue with a minimal impact. The self-assembly capability of the platform enables the high yield manufacture of three-dimensionally shaped devices that are relying on geometry/stress dependent physical effects that are evolving in magnetic materials including magentostriction and shape anisotropy. Developed arrays of giant magnetoimpedance sensors and cuff implants provide a possibility to address physiological processes locally or distantly via magnetic and electric fields that are generated deep inside the organism, providing unique real time health monitoring capabilities. Fabricated on a large scale shapeable magnetosensory systems and nanostructured materials demonstrate outstanding mechanical and electrical performance. The novel, shapeable form of electronics can revolutionize the field of mechanical prosthetics, wearable devices, medical aids and commercial devices by adding novel sensory functionalities, increasing their capabilities, reducing size and power consumption.

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