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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.
551

A Novel Hybrid Vehicle Architecture : Modeling, Simulation and Experiments

Chanumolu, Raviteja January 2017 (has links) (PDF)
Electric and hybrid vehicles are particularly suited for use in urban areas since city transportation is mainly characterized by relatively short driving distances, low continuous power requirements, long idling times and high availability of regenerative braking energy. These characteristics, when carefully incorporated into the design process, create valuable opportunities for developing clean, efficient and cost effective urban vehicle propulsion systems. In the first part of the thesis, we present data collected in the city of Bangalore, India from a very commonly seen mode of transportation for hire in India and other emerging economies, namely a three-wheeled vehicle known as the “auto-rickshaw”. From a statistical analysis, it is shown that the typical range is 72.5 km with a mean speed of 12.5 km/h. More than 60% of the time the auto-rickshaw is stationary or has a speed of less than 5 km/h. From a model of the auto-rickshaw, it is shown from simulations that 4 kW DC motor and about 10 kWh of electrical energy is enough to meet 80% of typical requirement. Based on this finding, in this thesis, a novel parallel hybrid architecture is proposed where two 2 kW DC hub motors are directly mounted on the wheels and an internal combustion (IC) engine output is connected to the stator of the DC hub motors to provide additional power when required. To match load and speed, a continuously variable transmission (CVT) is placed in-between the IC engine and the DC hub motor. The proposed hybrid configuration adds speed to the wheel output unlike the normal power split configuration which adds torque. One of the main objective of this work is to study and compare the performance of the above novel speed-addition and compare with the typical torque-addition configuration. A MATLAB/Simulink model for both the configurations, with DC hub motor and a small IC engine, has been created and the fuel consumption has been calculated. It is shown that the proposed speed-addition concept gives better fuel efficiency for the standard modified Indian Driving Cycle. The models have also been compared for actual driving data and an optimal control strategy has been developed using dynamic programming. It is again shown that the proposed speed-addition concept results in better fuel economy. In the last part of the thesis, a low cost experimental test-bed consisting of an auto-rickshaw IC engine, a CVT and a 2 kW DC hub motor has been developed to validate the speed-addition concept and compare with the torque-addition configuration. The torque-speed curves of the IC engine, the DC motor and both of them together, in the speed and torque-addition configuration, have been obtained. It is shown that the speed-addition concept does indeed work and the obtained results are significantly different from the torque-addition configuration.
552

Conformational Analysis Of Designed Alpha-Omega Hybrid Peptides

Roy, Rituparna Sinha 03 1900 (has links) (PDF)
The insertion of ω- amino acid residues as guests into host α-peptide sequences permits expansion of the range of polypeptide secondary structures. The term ω- amino acid is used to refer to the entire family of residues generated by homologation of the backbone of α - amino acid residues. This explores the consequences of insertion of substituted β-residues (β3) , unsubstituted β-residues , unsubstituted γ-residues (gamma aminobutyric acid) and unsubstituted δ-residues (delta aminovaleric acid) into host α -peptide sequences. Chapter 1 provides an introduction to the conformational properties of β-peptides and reviews current literature on the structural features of peptides containing ω-amino acid residues. The available crystallographic information is summarized. The conformational properties of β- residues may be described by three degrees of torsional freedom : φ (N – Cβ) , θ (Cβ -Cα) and ψ (Cα-CO). Similarly, the conformational properties of γ -residues is based on four torsional parameters ( φ , θ1 , θ2, ψ) and the conformational properties of δ - residues is based on five degrees of freedom ( φ , θ1 , θ2, θ3,ψ). The rational use of β -residues in peptide design requires an understanding of the nature of local conformations, which are readily accessible. The conformational space for β -residues can be represented in a three dimensional plot. The observed distribution of φ , θ and ψ values for β -residues in peptide crystal structures presented in this section permits a correlation - between the torsion angle θ and the secondary structure context. The gauche (g+ and g ) conformations induce helical folding and the trans conformation is generally observed in the strands of a hairpin. The most striking feature of hybrid sequences is the observation of novel hydrogen bonded rings in peptide structures. Chapter 2 describes the effects of insertion of β-residues into specific positions in the strand segments of designed peptide hairpins. Insertion of β -residues into the strands of a hairpin changes the orientation of peptide bonds, resulting in a “polar sheet” arrangement. The conformational analysis of three designed peptide hairpins composed of α/β - hybrid segments are described: Boc-Leu-βPhe-Val-DPro-Gly- Leu-βPhe-Val-OMe (BBH8) , Boc-βLeu- Phe-βVal-DPro-Gly-βLeu-Phe-βVal-OMe (BAB8) and CF3COO-H3N+-Leu-Val-Val-βPhe-DPro-Gly-βPhe-Leu-Val-Val-OMe (BHFF10). All the peptides have been characterized by 500 MHz 1H-NMR spectroscopy and several crucial long range NOEs confirm a predominant population of β-hairpin conformations in CD3OH. X-ray diffraction studies on single crystals of peptide BBH8 reveal a β-hairpin conformation, stabilized by three cross-strand hydrogen bonds and a Type II′β-turn at the DPro-Gly turn segment. Designed β-hairpin peptide scaffolds may be used to probe cross-strand sidechain interactions in β-sheet structures. A previously reported peptide β-hairpin, Boc-Leu-Phe-Val-DPro-Gly-Leu-Phe-Val-OMe exhibited an anomalous far UV CD spectrum, which was interpreted in terms of interactions between facing aromatic chromophores, Phe 2 and Phe 7 (Zhao, C.; Polavarapu, P.L.; Das,C. and Balaram, P. J. Am. Chem. Soc., 2000, 122, 8228-8231). In BBH8 and BHFF10 the two cross-strand βPhe residues are at non-hydrogen bonding positions, with the benzyl sidechains pointing on opposite faces of the β- sheet. BBH8 yields a “hairpin –like” CD spectrum, with a minimum at 224 nm. The CD spectrum of BAB8 reveals a negative band at 234 nm and a positive band at 221 nm suggestive of an exciton split doublet. BHFF10 yields a “hairpine-like” CD spectrum, with a negative band at 220 nm. Chapter 3 describes the synthesis and conformational characterization of three hybrid decapeptides : Boc-Leu-Val-βGly-Val-DPro-Gly- Leu-βGly -Val-Val-OMe (BHB10), Boc-Leu-Val-γAbu-Val-DPro-Gly- Leu-γAbu -Val-Val-OMe (BHC10) and Boc- Leu-Val-δAva-Val-DPro-Gly- Leu-δAva -Val-Val-OMe (BHD10). These peptides were designed to systematically investigate the effect of insertion of additional methylene groups into the strands of a hairpin. The incorporation of additional carbon atoms changes the local polarity of the strands. 500 MHz NMR studies establish that BHB10 and BHD10 adopt predominantly β- hairpin conformations in methanol, with interstrand registry established by observation of long range NOEs. The observation of both DPro 4 (CαH) ↔ Gly 5 (NH) and Gly 5 (NH) ↔ Leu 6 (NH) NOEs provides evidence for a Type II ′β - turn for all the hairpins. In BHC10, no long range NOEs were observed. However, X-ray diffraction studies in single crystals reveal a β- hairpin conformation, nucleated by a DPro-Gly Type II′β-turn. Chapter 4 describes an attempt to incorporate one or two ω amino acid residues in the turn region of a potential hairpin, in order to assess the effect of expansion of the nucleating turn. The DPro-LPro segment has been shown to stabilize β-hairpin conformations in both cyclic (Shankaramma,S.C.; Moehle, K. ; James, S.; Vrijbloed, J.W.; Obrecht,D and Robinson, J.A. Chem Commun. 2003,1842-1843) and acyclic sequences ( Raj Kishore Rai ; S.Raghothama and P. Balaram , unpublished results) . In the present study the following turn segments have been considered: βDPro -αLPro , βLPro -αLPro and βLPro -αDPro. The synthesis and conformational analysis of three octapeptide sequences -Boc-Leu-Phe-Val-βDPro-αLPro-Leu-Phe-Val-OMe (βDPαLP8), Boc-Leu-Phe-Val-βLPro-αLPro-Leu-Phe-Val-OMe (βLPαLP8)and Boc-Leu-Phe-Val-βLPro-αDPro-Leu-Phe-Val-OMe (βLPαDP8) are described. In the βDPro-αLPro peptide, NMR evidence clearly supports a β-hairpin conformation, with a nucleating hybrid βα turn stabilized by a C11 (4 →1) hydrogen bond. In the other two octapeptides, no evidence for folded structures was obtained. These results suggest that nucleating turn formation is facilitated only in the heterochiral βD-αL case. Further expansion of the turn segment in potential hairpins has been investigated by inserting two contiguous β-residues into the center of a host α-peptide sequence. The conformational studies on two synthetic hexapeptides, Boc-Leu-Phe-βDPhe-βLPro-Phe-Leu-OMe (βDFβLP6) and Boc-Leu-Phe-βLPhe-βLPro-Phe-Leu-OMe (βLFβLP6) suggest that the βDPhe-βLPro segment is capable of forming a C12 turn in methanol. Two octapeptide sequences, Boc-Leu-Val-Leu-βDPhe-βLPro-Leu-Phe-Val-OMe (βDFβLP8N) and Boc-Leu-Val-Val-βDPhe-βLPro-Leu-Val-Val-OMe (βDFβLP8V) have also been investigated to probe the possible formation of hairpin structures. In these cases, spectroscopic analysis is hampered by the presence of multiple conformations, because of the tendency of the βDPhe-βLPro bond to exist in both cis and trans conformations. NMR studies on the conformational properties of a hexapeptide Boc-Leu-Val-βDPro-βLPro-Leu-Phe-OMe (βDPβLP6) in CDCl3 reveal that in the major conformer the Val 2(NH) ↔ Leu 5 (NH) NOE is observed, suggesting the presence of a 12-membered hydrogen bonded turn. A ββ - segment can give rise to two types of hydrogen bonded rings , 10 – membered (C10) and 12- membered (C12). In an attempt to generate C10 turns, an N-methylamino acid has been inserted next to a ββ - segment, preventing the formation of the 12 – membered turn. In such a situation formation of a 10-membered turn, with reverse hydrogen bond directionality, may be facilitated. The conformational properties of Boc-Leu-Val-βDPhe-βLPro-(N-Me) Leu- Phe-OMe (βDFβLPNMeL6) has been studied by 500 MHz NMR spectroscopy. The data suggests the formation of a C11 turn at the βLPro- (N-Me) Leu segment in CDCl3-DMSO mixtures, instead of formation of a C10 turn at the βDPhe -βLPro segment. Studies on the peptide Boc-Leu-Phe-Val-βLPro-(N-Me) Leu-Leu-Phe-Val-OMe (βLPNMeL8) also suggest the absence of turn formation and folded structures. In hybrid sequences, an important question to be addressed is whether ω amino acids can be accommodated into helical structures. Two contiguous β- residues have been inserted into a helical sequence. The conformational properties of a 11- residue peptide, Boc-Val-Ala-Phe-Aib-βVal-βPhe-Aib-Val-Ala-Phe-Aib-OMe (ABA11) are described in Chapter 5. This sequence was based on the parent α- peptide Boc-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe, which adopted a complete helical conformation in crystals (Aravinda, S.; Shamala, N.; Das, C .; Sriranjini, A.; Karle, I.L. and Balaram, P. J. Am. Chem. Soc. 2003, 125, 5308-5315). 500 MHz 1H-NMR studies establish a continuous helix over the entire length of the peptide in CDCl3 solution , as evidenced by diagnostic nuclear Overhauser effects. The molecular conformation in crystals reveals a continuous helical fold, stabilized by seven intramolecular hydrogen bonds. The characterization of two synthetic octapeptides Boc-Val-Ala-βPhe-Aib-Val-Ala-βPhe-Aib-OMe (VAβFU8) (βPhe residues have been incorporated at (i /i+4 positions) and Boc-Val-Ala-βPhe-Aib-βPhe-Ala-Val-Aib-OMe (βFUβF8) (βPhe residues have been incorporated at (i /i+2 positions) is also presented. NMR data suggests the retention of helical conformation in both the peptides. In order to delineate the conformations of hybrid peptides with three contiguous β-residues, two peptides have been synthesized Boc-Phe-Aib-βGly-βLeu-βPhe-Aib-Val-Ala-Phe-Aib-OMe (ABA10) and Boc-Val-Ala-Phe-Aib-βGly-βLeu-βPhe-Aib-Val-Ala-Phe-Aib-OMe (ABA12). NMR studies in chloroform support continuous helical conformation in the decapeptide.
553

Hybrid War: A Conceptual History Study : The meaning of hybrid war in the scholarly debate between 2008-2021

Lindberg, Filippa January 2021 (has links)
This thesis examines the meaning and construction of the debated concept of hybrid war/warfare in the existing scholarly literature. The identified research problem stems from the lack of reflection on the conceptual reasoning and thought that underpins the nature of war, which relates to the fact that a historical linguistic perspective is neglected in most studies on war. Through this study, conceptual history theory has demonstrated its utility in War Studies by illustrating the benefit of applying a historically focused lens on debated and contested concepts. Thus, demonstrating how both a synchronic and diachronic perspective is necessary to examine how the meaning and construction of a concept change over time.  The analysis aims to answer the question of how the meaning of the hybrid war concept has developed in the existing body of literature between 2008-2021. Based on the analysis, it was observed that the greatest shift in terms of the meaning and use of the concept occurred after the Russian annexation of Crimea in 2014. The previously optimistic anticipation of hybrid war in future was replaced with a more critical understanding of the concept itself, and the prospect of its future. All in all, the result of this thesis, beside the observed shift in the meaning and construction of the hybrid war concept, is that conceptual history theory can contribute to the understanding of contested and debated concepts related to the nature of war.
554

Hybridledarskapets bidrag till medarbetarnas engagemang / Hybrid leadership's contribution to employee engagement

Jönsson, Carina, Hakopian, Katrin January 2022 (has links)
Bakgrund och problem Den pågående globaliseringen och digitaliseringen bidrar till en förändrad kontext för många organisationer och dess arbetsformer. Utvecklingen sker snabbt och utmaningen är för många organisationer de mjuka värdena såsom ledarskap, relationer, kommunikation, kultur och engagemang. Nya tekniska lösningar möjliggör för ständig nåbarhet, vilket öppnar upp för att arbeta var som helst och när som helst. Steget från en traditionell- till en hybrid arbetsplats inbegriper såväl ledarskap som medarbetarskap där organisationens arbetssätt, roller och kommunikationsvägar kan komma att utvecklas beroende på vilken organisationskultur som råder. Hybridarbetsplas och hybridledarskap medför olika utmaningar för medarbetarna, vilka de behöver kunna hantera självständigt utan ledarens ständiga närvaro och vägledning. Utmaningarna består bland annat i att medarbetarna behöver få de kompetenser, ansvar och befogenheter så att de skall kunna utvecklas till självgående och initiativtagande individer. Ett väl utvecklat medarbetarskap innebär att medarbetarna anser att arbetsuppgifterna är meningsfulla, vilket kan leda till medarbetarnas engagemang.   Syfte och metod Syftet med studien är att beskriva och analysera hur hybridledarskap kan bidra till medarbetarnas engagemang, detta för att erhålla fördjupad kunskap. Baserat på studiens syfte används en kvalitativ metod med semistrukturerade intervjuer som datainsamlingsmetod. Studien är genomförd på en organisation som arbetar med folkbildning inom den ideella sektorn i Sverige. Slutsats Studien visar på att det finns tydliga indikationer på att hybridledarskap kan bidra till medarbetarnas engagemang genom att skapa förutsättningar för ett fungerande medarbetarskap. Föreliggande studie visade på fyra teman med tillhörande faktorer som bidrar till medarbetarnas engagemang; kommunikation och tillgänglighet (digitala verktyg, lyhördhet och närvarande, flexibilitet och transparens), förväntningar på prestation (trygghet i arbetsroller, tydliga förväntningar, kontinuerlig uppföljning), självständighet (tydliga roller och ansvar, kunskap och kompetens, samverkan) och meningsfulla arbetsuppgifter (värderingar, delaktighet och göra skillnad). / Background and problem The ongoing globalization and digitalization contribute to a changed context for many organizations and their working methods. This development changes rapidly and the challenge for many organizations is often the soft values such as leadership, relationships, communication, culture, and commitment. New technical solutions enable constant accessibility, which opens up for working anywhere and anytime. Mowing from a traditional workplace to a hybrid workplace includes both leadership and employees, where the organization's working methods, roles, and communication paths may be developed depending on the organizational culture. Hybrid workplaces and hybrid leadership pose various challenges for employees, which they need to be able to handle independently without the leader's constant presence and guidance. These challenges include the fact that employees need to give the skills, responsibilities, and powers so that they can develop into independent and initiative-taking individuals. A well-developed co-operation means that the employees consider the tasks to be meaningful, which can lead to employee engagement. Purpose and method The purpose of the study is to describe and analyze how hybrid leadership can contribute to 2employee engagement, in order to obtain in-depth knowledge. Based on the purpose of the study, a qualitative method is used with semi-structured interviews as a data collection method. The study was conducted at an organization that works with public education in the non-profit sector in Sweden. Conclusion The study shows that there are clear indications that hybrid leadership can contribute to employee engagement by creating the conditions for a functioning employeeship. The present study identified four themes and associated factors that contribute to employee engagement; communication and accessibility (digital tools, responsiveness and presence, flexibility and transparency), expectations for performance (confident in job, clear expectations, continuous follow-up), independence (clear roles and responsibilities, knowledge and skills, collaboration) and meaningful tasks (values, participation and make a difference).
555

Hybrid Composite Materials and Manufacturing

Diana Gabrielle Heflin (12507373) 05 May 2022 (has links)
<p>Composite materials have become widely used for high-performance applications, particularly in the aerospace industry where annual production volumes are low and a higher part cost can be supported. During the last decades composite materials are beginning to see use in a broader range of applications, including the automotive and sports equipment industries. Simultaneously, there is increasing demand from consumers and regulatory bodies to make cars more fuel efficient and in the case of EV’s longer drive range, which can be accomplished by reducing vehicle weight. Composite materials have high specific stiffnesses and strengths, resulting in weight savings when they are used to replace traditionally metal components. However, in order for widespread adoption of composite parts to be viable for the automotive industry, high-rate manufacturing must be realized to reach the required production volumes and part costs.</p> <p>Toward this goal, advanced composite manufacturing techniques have been developed. These techniques typically combine high automation with careful material selection, which can include fast-curing resins and thermoplastics with adapted melt viscosities and thermomechanical properties. They also allow for complex part geometries to be produced in a single step, reducing the need for additional assembly time. Further, they can be used to easily create multi-material components, which can result in parts that benefit from the desirable mechanical properties of the constituent materials without sacrificing performance.</p> <p>This thesis develops a framework for the design and high-rate manufacture of multi-material components. First, a critical literature review is conducted to develop a clear understanding of existing research into combinations of dissimilar materials, including epoxy/polyamide, thermoplastic elastomer/polyamide, and aluminum/thermoplastic. It is shown that, for all material combinations studied, interfacial delamination and subsequent deformation are the primary energy absorption mechanisms and that manufacturing conditions may affect interfacial bond strength. Based on this foundation, adhesion testing is performed on devoted sample configurations fabricated under controlled molding conditions. For these material combinations, interfacial adhesion can be significantly improved with carefully selected processing temperatures, even to the extent that adhesive bond between dissimilar materials can be stronger than the cohesive bond in the constituent materials. Next, impact and quasi-static indentation testing were performed to determine the effects of interfacial adhesion and part design on crash performance. The materials tested all benefit from the placement of a more ductile material on the impacted side of the sample (top surface), indicating a more favorable dissipation of the contact stresses from the impactor, and a higher strength material on the bottom surface where it can withstand tensile stresses imposed by impact-induced bending. </p> <p> Finally, a complex part consisting of a unidirectional polyamide/carbon fiber preform and a thermoplastic overmold is manufactured via a hybrid overmolding process. Interfacial temperature during overmolding is varied to confirm if the same improvements in interfacial bond strength seen in the compression molding test samples are attainable under realistic high-rate manufacture conditions. Additionally, the preform volume is varied to examine the effect of the preform reinforcement on a part’s bending performance. For this system, varying the preform temperature had no effect on interfacial bond strength. A predictive technical cost model is also used to determine the effect of manufacturing changes on part costs. Increasing the tow volume three-fold increased the absorbed energy by more than 30% and requires an increased cost of only 3.8%. </p> <p>This thesis proves that a tough, multi-material part can be rapidly produced via hybrid overmolding. It was demonstrated that a complex shaped part could be produced at a complete line cycle time of approximately 90 secondsmaking it a viable method to produce high-performance, low-cost components. </p>
556

Framtidens hybrida stridsfordon / Future hybrid combat vehicle

Sundell, Jacob January 2022 (has links)
Stridsfordon 90 tillsammans med Stridsvagn 122 är i dagsläget stommen i Försvarsmaktens mekaniserade bataljoner. I Försvarsbeslutet 2020 beslutades det att Stridsfordon 90 skall successivt ersättas med ett nytt stridsfordon efter 2030. Enligt en rapport från Totalförsvarets forskningsinstitut skall teknik som är mogen 10 år innan förbanssättande av en ny plattform nyttjas för att ge tillräckligt med tid för upphandling, systemintegrering, driftsättning med mera. Totalförsvaret forskningsinstitut har även identifierat att hybriddrift av stridsfordon anses vara redo att införas efter 2025.  Med bakgrund i ovanstående konstruerades ett koncept för en hybriddrivlina för framtidens stridsfordon för att besvara frågeställningen, hur påverkar seriehybriddrivlinans tekniska ramvillkor framtidens stridsfordon och hur påverkar detta stridsfordon på taktisk nivå? Konceptetes drivlina sattes ihop med tillgänglig teknologi som går att anskaffa på marknaden och valdes efter prestanda som var bättre eller liknande som Stridsfordon 90.  Efter att konceptet hade konstruerats genomfördes två analyser med olika batterivikt. Den första analysen hade en batterivikt på 660kg och den andra 3860kg. Dessa två vikter dimensionerades efter totalvikten på Stridsfordon 90A och Stridsfordon 90C. Resultatet av analysen är att med en seriehybriddrivlina får framtidens stridsfordon en ökad prestanda, förmåga att köra på batteridrift och en högre verkningsgrad.   Med resultatet från analyserna diskuterades förväntade förändringar i förmågorna rörlighet, uthållighet och skydd. Diskussionen ledde fram till slutsatserna att framtidens stridsfordon kan med en seriehybriddrivlina erhålla en bättre teknisk prestanda vilket ökar förmågan rörlighet. Stridsfordonen får även en bättre verkningsgrad vilket gör att stridsfordonen får en bättre uthållighet samt en mindre infraröd signatur och således ett bättre skydd vid strid i mörker. Till sist kan även fordonen drivas helelektriskt vilket skapar möjligheter för den taktiska chefen att välja ett mer dolt uppträdande med stridsfordonen. / Combat Vehicle 90 together with Stridsvagn 122 is currently the backbone of the Swedish Armed Forces mechanized battalions. In the defence decision from 2020, the Swedish parliament decided that Combat Vehicle 90 will be gradually replaced with a new combat vehicle after 2030. According to a report from the Swedish Defence Research Agency, technology that is mature 10 years before deployment of a new platform will be used to provide sufficient time for procurement, system integration, commissioning and more. The Swedish Defence Research Agency has also identified that hybrid propulsion of combat vehicles is considered mature and ready to be introduced after 2025. Based on the above, a concept was constructed for a hybrid driveline for future combat vehicles to answer the question. How do the technical framework conditions of the hybrid series driveline affect the combat vehicles of the future and what will be the consequences on a tactical level? The concept's driveline was put together with existent technology that can be acquired on the market and was chosen according to performance that was better or similar to Combat Vehicle 90. After the concept had been designed, two analyzes were performed with different battery weights for the concept. The first analysis had a battery weight of 660kg and the second 3860kg. These two weights were dimensioned according to the total weight of Combat Vehicle 90A and Combat Vehicle 90C. The result of the analysis is that with a hybrid series driveline, the combat vehicles of the future will have increased performance, the ability to run on battery power and a higher efficiency. With the results, expected changes in mobility, endurance and protection were discussed. The query led to the conclusions that the combat vehicles of the future can, with a hybrid series driveline, obtain a better technical performance, which increases the mobility. The combat vehicles also have a better efficiency, which means that the combat vehicles have a better endurance and a smaller IR-signature and therefore, an enhanced protection on low light warfare. Finally, the vehicles can also be all-electrically driven, which creates opportunities for the tactical commander to choose one with stealth behaviour with the combat vehicles.
557

Viability of Power-Split Hybrid-Electric Aircraft under Robust Control Co-Design

Bandukwala, Mustafa January 2021 (has links)
No description available.
558

Design and Applications of Hybrid Switches in DC-AC Power Converter Topologies

Fox, Ian Micah January 2018 (has links)
No description available.
559

Power Electronic Enhanced Distribution Transformer : Seamless Voltage Regulation with Extended Functionalities / Kraftelektronik Förstärkt Distributionstransformator : Sömnlös Spänningsreglering med Extra Funktioner

Johansson, Nils January 2022 (has links)
On-load tap changers and static synchronous compensators (STATCOM) are the main components for voltage regulation and power quality optimization in the power system. STATCOMs are used in both industrial applications and utility to stabilize the grid and reduce downtime. STATCOM is based on power electronics that is put together as a voltage source converter. However, as STATCOMs are connected in shunt, they provide voltage regulation indirect, by the injection of reactive power. Which might be insufficient for emerging grid codes and power systems with less inertia. This thesis’s purpose is to investigate a series voltage source converter (SVSC), which is connected in series with the grid. Series connected devices may provide better voltage regulating capabilities than shunt devices with the same amount of reactive power compensation, as it can regulate the voltage directly. The SVSC can also be used for power system compensation and power flow control. The SVSC consists of a Chain-Link Modular Multilevel Converter that is connected directly in series with the power system without a coupling transformer. The SVSC injects a voltage in quadrature with the current through the SVSC, this gives the SVSC the ability to emulate a reactance, along with increasing the voltage. The maximum injected voltage from the SVSC is 30% of the system voltage. As the voltage is injected in quadrature with the current, the SVSC can change to voltage more if the power factor is low. The SVSC is able to keep the voltage on the load side constant in several different load and grid scenarios. Furthermore, the SVSC was able to emulate both a capacitance and an inductance, and control the active power flow. However, the SVSC was not able to regulate the voltage as desired when the power factor is close to 1. / Lindningsomkopplare och static synchronous compensators (STATCOM) är de huvudsakliga komponenterna för spänningsreglering och elkvalité optimering i elnätet. STATCOMs används i både industrin och av elnätsägare för att stabilisera elnätet och minska driftstopp. STATCOM är baserat på kraftelektronik som är byggt till en voltage source converter. I alla fall, eftersom STATCOMs är anslutna i shunt med elnätet, kan de endast spänningsreglera indirekt, genom att tillföra reaktiv effekt. Vilket kan vara otillräckligt med nya elnätsregler och elnät med lägre tröghet. Den här avhandlingens syfte är att undersöka en series voltage source converter (SVSC), som är ansluten i serie med elnätet. Enheter som är anslutna i serie med elnätet kan leverera bättre spänningsreglering än enheter som är anslutna i shunt med samma mängd reaktiv effekt kompensering. SVSC:n kan också användas för lednings kompensering och effektflödes kontroll. SVSC:n består av en Chain-Link Modular Multilevel Converter som är ansluten i serie med elnätet utan en kopplingstransformator. SVSC genererar en spännings som är i kvadratur med strömmen genom SVSC:n, det gör att SVSC kan emulera en reaktans, men även öka spänningen. Den maximala spänningen från SVSC:n är 30% av systemspänningen. Eftersom spänningen är i kvadratur med strömmen, så kan SVSC ändra spänningen mer om effektfaktorn är låg. SVSC:n kan hålla spänningen konstant på last sidan under flera olika last- och elnäts scenarier. Dessutom kunde SVSC:n emulera både en induktans och kapacitans, och kontrollera det aktive effektflödet. Men, SVSC:n kunde inte reglera spänningen som önskat när effektfaktorn var nära 1.
560

NOVEL HIGH-RATE MANUFACTURING PROCESS FOR MULTIFUNCTIONAL THERMOPLASTIC COMPOSITES

Jessica Lavorata Anderson (17593293) 11 December 2023 (has links)
<p dir="ltr">In pursuit of enhanced fuel economy, the automotive industry is exploring the substitution of metal components with lightweight polymer composites. These components must withstand elevated static loading and crash performance, while ideally offering added functionalities and reduced weight. To tackle these challenges, this research presents an innovative manufacturing method aimed at reducing costs and cycle times associated with continuous fiber polymer composites. This method involves producing a linear thermoplastic composite rod known as M-TOW (Multi-tow), which can be molded into intricate shapes to serve as tailored structural reinforcement in hybrid-molded parts. The research encompasses the processing of M-TOW, with a focus on predicting consolidation using Darcy’s law, integrating functional components for thermal and electrical conductivity using overbraided metallic wire or sensing using optical fibers, and its application in real-world scenarios. These advancements showcase the versatility and potential of M-TOW in high-rate continuous fiber manufacturing, paving the way for multifunctional hybrid molded structures.<br><br></p>

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