Orientadores: Rogerio de Fraga, Paulo Cesar Rodrigues Palma / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T22:24:52Z (GMT). No. of bitstreams: 1 Cardia_FishilerPimentelZitenfeld_M.pdf: 1370656 bytes, checksum: 9c1061423f4725bab06c637f1e6c0958 (MD5) Previous issue date: 2009 / Resumo: A crescente utilização de telas de polipropileno em cirurgia pélvica reconstrutiva levou ao aparecimento de complicações inerentes ao uso dos materiais sintéticos, tais como retração, exposição e infecção. Com o objetivo de avaliar a retração de telas de polipropileno de media gramatura e melhorar a incorporação da mesma através de orifícios de 5 mm de diâmetro, realizamos um estudo experimental "in vivo". Método: No presente estudo, avalia a morfologia e a densidade volumétrica das fibras de colágeno em malhas com e sem orifícios padronizados, bem como; a retração das mesmas, por meio de mensuração radiográfica e direta da tela. A amostra consistiu de 14 ratas fêmeas da raça Wistar, que foram sacrificadas 90 dias após o implante. O abdômen foi ressecado e radiografado antes de ser preparado o estudo histológico e estereológico. A distribuição do colágeno foi avaliada por estereologia nos três compartimentos: pele, fascia de Colles e na região do implante da Tela entre a fascia de Colles e a aponeurose dos músculos retos abdominais. Resultados: Não houve retração das telas de polipropileno nas aferições radiográficas e medidas diretas. A estereologia evidenciou deposição de fibras de colágenos organizadas nos orifícios. Ao contrário nas telas sem orifícios, a deposição de colágeno foi maior e desorganizada, com cistos de inclusão. Outro dado relevante foi que a estrutura das fibras de colágeno apresentou-se morfologicamente normal nos animais de tela com orifício, e houve uma maior proximidade entre a pele e a musculatura no local do orifício. Conclusões: A análise histológica revelou menor reação inflamatória nas telas com macro orifícios. A avaliação estereológica da densidade volumétrica das fibras de colágeno nas telas com e sem orifícios, permitiu observar que os macro orifícios agiram como fator facilitador da integração do enxerto e que poderá representar implicações na parte clinica médica. Palavras chaves: Polipropileno; Telas cirúrgicas / Abstract: The meshes in reconstructive pelvic surgery have led to complications inherent to the use of synthetic materials, such as retraction, exposure and infection. In order to improve mesh integration we created standardized orifices, 5 mm in diameter of monofilament polypropylene mesh and compared local tissue reaction with regular meshes in an animal study. Method: We evaluated the morphology and volumetric density of collagen fibers in meshes with and without standardized orifices, as well as its retraction through radiographic and direct measurement of the meshes. The sample consisted of 15 female Wistar rats, which were sacrificed 90 days after the implant. The abdominal wall was removed and x-ray was taked before its preparation for histological and stereological study (estimate the density of an element of a homogeneous area). The volumetric density of the collagen fibers was calculated by stereological tool in three compartments: skin, Colles' fascia and mesh, the latter located between the Colles' fascia and the aponeurosis of the rectus abdominalis muscles. Results: There was no retraction of the polypropylene meshes. The histological and stereological analysis disclosed organized collagen fiber deposition in the orifices and less inflammatory reaction than the control meshes with no orifices. Conclusions: There was no mesh retraction in both groups. The histological and stereological results suggest that the standardized orifices facilitated tissue integration and may have clinical application. Keywords: Polypropylene; Surgical meshes / Mestrado / Cirurgia / Mestre em Cirurgia

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No. of bitstreams: 2 Dissertação - Lorena Costa Vasconcelos Macedo - 2016.pdf: 2158010 bytes, checksum: 6fe7ebd2c875341e61444e1eaf37fa19 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-18 / This study examined the performance of pineapple bagasse for the production of reducing sugars after pretreatment with alkaline hydrogen peroxide and acid and enzymatic hydrolysis. They were determined after conducting preliminary acid and enzymatic hydrolysis the best conditions for the bagasse pineapple used in dry form, "in natura" and washed. Chosen the dry pomace condition, this was separated granulometrically, wherein the average diameter fractions of 1.242 mm and 0.564 mm were predominant among the amounts of sieved bagasse, these two fractions were then chosen and denominated 20 and 48 mesh respectively, to evaluate the influence of particle size on the release of total reducing sugars. Type DCCR designs were conducted to evaluate the influence of weather pretreatment (h) Temperature (°C) and concentration of alkaline hydrogen peroxide (%) in the performance of acid and enzymatic hydrolysis, which was measured by the release of total reducing sugars (TRS). Moreover, the mass loss caused in the samples 20 and 48 mesh after pretreatment with alkaline hydrogen peroxide were observed. The results showed that the highest yields of reducing sugars obtained for fractions 20 and 48 mesh, both the acid hydrolysis with diluted sulfuric acid 2.9% (v/v) as the enzymatic hydrolysis with 9 FPU / g dry biomass at 50 °C and pH 4.8, were obtained when using lower levels of time, temperature and concentration of peroxide to the pre-treatment with hydrogen peroxide. The ART mass analysis after 8 h of reaction at 20 °C and concentration of alkaline hydrogen peroxide at 2% (v/v) to acid and enzymatic hydrolysis at residue 20 mesh, were 0.092 g/g ART dry bagasse and 0.063 g/g of dry bagasse ART respectively. As for the enzymatic and acid hydrolysis in the residue 48 mesh under the same conditions was 0.074 g/g dry bagasse ART and 0.058 g/g ART respectively. Therefore, it is believed that the smaller mass loss is related to obtaining higher yield of reducing sugars. This is because, observing the mass losses of such biomasses intended to acid and enzymatic hydrolysis, in both fractions pineapple pulp, 20 and 48 mesh after pretreatment with alkaline hydrogen peroxide were detected smaller mass loss of 77.829% and 83.182% for bagasse of 20 mesh and 83.724% and 83.493% for the bagasse of 48 mesh. / Neste trabalho analisou-se o desempenho do bagaço de abacaxi para produção de açúcares redutores após o pré-tratamento com peróxido de hidrogênio alcalino e hidrólises ácida e enzimática. Foram determinadas após a realização de prévias da hidrólise ácida e enzimática as melhores condições para os bagaços do abacaxi usados sob a forma seca, “in natura” e lavada. Escolhida a condição do bagaço seco, este foi separado granulometricamente, sendo que as frações de diâmetro médio de 1,242 mm e 0,564 mm apresentaram predomínio dentre as quantidades do bagaço peneirado, estas duas frações foram então escolhidas e denominadas de 20 e 48 mesh respectivamente, com o objetivo de avaliar a influência do tamanho da partícula na liberação dos açúcares redutores totais. Foram realizados planejamentos do tipo DCCR a fim de avaliar a influência do tempo de pré-tratamento (h), temperatura (°C) e concentração de peróxido de hidrogênio alcalino (%) no desempenho das hidrólises ácida e enzimática, que foi mensurado pela liberação de açúcares redutores totais (ART). Além disso, foram observadas as perdas mássicas ocasionadas nas amostras de 20 e 48 mesh após o pré-tratamento com peróxido de hidrogênio alcalino. Os resultados demostraram que os maiores rendimentos em açúcares redutores, obtidos para as frações, de 20 e 48 mesh, tanto na hidrólise ácida com ácido sulfúrico diluído 2,9% (v/v), quanto na hidrólise enzimática com 9 FPU/g de biomassa seca a 50°C e pH 4,8, foram obtidos quando se utilizou os menores níveis de tempo, temperatura e concentração de peróxido para o pré-tratamento com peróxido de hidrogênio. As análises de massa de ART após 8 h de reação, temperatura de 20°C e concentração de peróxido de hidrogênio alcalino a 2% (v/v) para a hidrólise ácida e enzimática no bagaço de 20 mesh, foram 0,092 g/g de ART bagaço seco e 0,063 g/g de ART bagaço seco respectivamente. Enquanto para a hidrólise enzimática e ácida no bagaço de 48 mesh nas mesmas condições foram 0,074 g/g de ART bagaço seco e 0,058 g/g de ART, respectivamente. Portanto, acredita-se que a menor perda mássica relaciona-se ao maior rendimento na obtenção de açúcares redutores. Isto porque, observado as perdas mássicas nessas biomassas destinadas às hidrólises ácidas e enzimáticas, em ambas as frações do bagaço de abacaxi, 20 e 48 mesh, após o pré-tratamento com peróxido de hidrogênio alcalino foram detectadas as menores perdas mássicas de 77,829% e 83,182% para os bagaços de 20 mesh e de 83,724% e 83,493% para os bagaços de 48 mesh.

Orientadores: Cássio Luís Zanettini Riccetto, Benedicto de Campos Vidal / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-21T17:40:56Z (GMT). No. of bitstreams: 1 Siniscalchi_RodrigoTeixeira_D.pdf: 4712721 bytes, checksum: 84737665d5451453e82931eab2e748c4 (MD5) Previous issue date: 2012 / Resumo: Introdução: O material sintético (tela) mais utilizado atualmente no tratamento da Incontinência Urinária de Esforço (IUE) e dos prolapsos da parede vaginal, também conhecidos como Prolapsos dos Orgãos Pélvicos (POP) é o polipropileno monofilamentar, com índices de cura de até 90%. Porém, as complicações relacionadas à integração tecidual desses implantes são relativamente prevalentes. O colágeno, por ser um material biologicamente compatível, pouco imunogênico e com propriedades moduladoras do processo inflamatório, pode ser utilizado como um importante agente cicatrizante e, nesse sentido, poderia melhorar a integração das telas. Objetivo: Estudar os efeitos biomecânicos e histológicos do recobrimento de tela de polipropileno monofilamentar com gel purificado de colágeno, implantadas no tecido subcutâneo de ratas. Material e Métodos: Vinte ratas foram utilizadas para o estudo histológico e outras 20 para o estudo biomecânico. De um lado da parede abdominal do animal foi implantado um fragmento tela de polipropileno monofilamentar macroporosa medindo 20 x 10 mm, habitualmente utilizada no tratamento da IUE e dos POP (Grupo I), denominada PLP (tela de polipropileno) e do outro lado foi implantada uma tela com as mesmas dimensões recoberta com gel purificado de colágeno (Grupo II), denominada PLP+C (tela de polipropileno recoberta com o gel purificado de colágeno). De acordo com o tempo de eutanásia (7, 30, 90 ou 180 dias) após o implante os animais de cada grupo foram divididos em quatro subgrupos contendo cinco animais cada. Foi então realizada excisão em bloco da parede abdominal para as análises. O estudo biomecânico foi realizado em um tensiômetro de precisão, no qual a tela era tracionada em sentido uniaxial até que se desprendesse da interface tecidual. Para quantificar a aderência do material, em cada grupo, foi analisada a carga máxima necessária para este desprendimento. No estudo histológico foram analisadas as características relativas à inflamação aguda e crônica além do tecido de granulação, formação de granuloma e reação de corpo estranho em lâminas coradas com Hematoxilina-Eosina (HE), utilizando-se de método semiquantitativo. A organização supramolecular da deposição colágena em torno das telas foi estudada através de microscopia de polarização (birrefringência). Resultados: No estudo biomecânico observou-se que a aderência das telas de polipropileno aos tecidos circunvizinhos aumentou significativamente após o recobrimento com o gel purificado de colágeno, como demonstrado na análise dos valores encontrados para a Carga Máxima no 7º (p=0,0016), 14º (p=0,0039), 90º (p=0,0009) e 180º (p=0,0029) dias após o implante. Considerou-se nessa pesquisa, que o aumento da biocompatibilidade da tela de polipropileno seria alcançado quando, na interface tecidual, houvesse redução da intensidade do processo inflamatório. Verificou-se que a resposta inflamatória crônica e aguda (neutrofílica), assim como a formação de tecido de granulação foi menos intensa, respectivamente p=0,004, p<0,001 e p=0,001 nas telas recobertas com o colágeno na fase inicial (7º e 14º dias) e ausente, assim como nas telas não recobertas na fase tardia (90º e 180º dias). A inflamação granulomatosa foi observada de forma menos significativa aos sete dias após o implante nos animais do grupo II (p=0,029) e em ambos os grupos, de maneira similar, diminuiu ao longo do tempo não mostrando diferença significativa. A reação de corpo estranho foi menos intensa na fase inicial no grupo II (p<0,001) e semelhante entre os grupos na fase tardia. Nas análises de birrefringência foi observado no período inicial (sete dias) uma maior densidade média de brilho (transmitância) a favor das telas não recobertas (p=0,000), porém nos outros períodos analisados a densidade média de brilho foi maior nas tela do grupo II (PLP+C), 14 dias (p=0,000), 90 dias (p=0,000) e em 180 dias (p=0,000). Conclusão: O recobrimento das telas de polipropileno com o gel purificado de colágeno aumentou sua aderência aos tecidos, quando implantadas na interface da parede abdominal de ratas adultas, tanto precocemente quanto tardiamente; promoveu uma resposta inflamatória menos intensa e duradoura e na fase tardia do implante desencadeou maior organização e empacotamento das fibras de colágeno. Estes dados inferem que a tela recoberta com o gel purificado de colágeno quando locada em seu leito de implante terá, provavelmente, menor mobilidade e também uma melhor adaptação e integração ao corpo do hospedeiro resultando em menor chance de complicações / Abstract: Introduction: The synthetic material most currently used in the treatment of stress urinary incontinence (SUI) and vaginal wall prolapse, also known as pelvic organ prolapse (POP) is the monofilament polypropylene mesh (PLP). However, complications related to tissue integration of these implants are relatively prevalent. Collagen is the main structural protein of mammals, which modulates inflammatory process, and can be used as an important healing agent and, accordingly, could improve the integration of the meshes. Objetives: To study the biomechanical and histological effects of PLP, coated with purified collagen gel, implanted in the subcutaneous tissue of adult rats. Methods: Twenty rats were used for histological study and other 20 for the biomechanical study. At one side of the abdominal wall, PLP fragment measuring 20x10 mm was implanted (Group I), and in the other side a mesh fragment with the same dimensions coated with purified collagen gel PLP+C) was implanted (Group II). According to the time of euthanasia (7, 30, 90 or 180 days) after implantation the animals from each group were divided into four subgroups of five animals each. The biomechanical study was performed with a precision tension meter with in bloc fresh abdominal wall sample containing the mesh. The mesh was pulled up in uniaxial direction until complete detachment of the tissue interface and the maximum load required for the detachment was analyzed in each group. In the histological study, it was examined characteristics of the acute and chronic inflammatory reaction, granulation tissue, granuloma formation, and foreign body reaction on slides stained with hematoxylin-eosin. The supramolecular organization of the collagen deposition around the meshes was studied with polarizing microscopy (birefringence analysis). Results: In biomechanical study it was observed that the adhesion of PLP to surrounding tissues increased significantly after coating with purified collagen gel, as shown in the analysis of the maximum load at the 7th (p=0.0016), 14th (p=0.0039), 90th (p=0.0009) and 180th (p=0.0029) days after implantation. It was considered in this research, that increased biocompatibility of PLP would be achieved when, in tissue interface, there was a reduction of the intensity of the inflammatory process. It was found that the acute and chronic inflammatory response, as well as the formation of granulation tissue were less intense, respectively p=0.004, p<0.001 and p=0.001 for PLP+C in the initial phase (7th and 14th days) and missing, as well as on the meshes not covered in late phase (90th and 180th days). Granulomatous inflammation was less significant seven days after implantation in animals of Group II (p=0.029) and in both groups, similarly, decreased over time showing no significant difference. The foreign body reaction was less intense in the initial phase in Group II (p<0.001) and similar between the groups in the late phase. In the birefringence analyses, it was noted a greater average density of brightness (transmittance) in PLP (p=0.000) in the initial period (seven days), but in other periods it was greater for PLP+C [14 days (p=0.000); 90 days (p=0.000) and 180 days (p=0.000)]. Conclusions: Coating of polypropylene meshes with purified collagen gel increased their adhesion to the tissues, when implanted in the subcutaneous of the abdominal wall of adult rats and promoted a less intense and lasting inflammatory response and, in the late stage of the implant, triggered greater organization and packaging of collagen fibers. Based on that, one can suppose that mesh coated with purified collagen gel can fix better to the host tissues preventing its displacing, and can elicit fewer integration defects, resulting in less chance of complications / Doutorado / Fisiopatologia Cirúrgica / Doutor em Ciências

Automatic mesh optimization algorithms suffer from the problem that humans are not uniformly sensitive to changes on different parts of the body. This is a problem because when a mesh optimization algorithm typically measures errors caused by triangle reductions, the errors are strictly geometrical, and an error of a certain magnitude on the thigh of a 3D model will be perceived by a human as less of an error than one of equal geometrical significance introduced on the face. The partial solution to this problem proposed in this paper consists of detecting the faces of the 3D assets to be optimized using conventional, existing 2D face detection algorithms, and then using this information to selectively and automatically preserve the faces of 3D assets that are to be optimized, leading to a smaller perceived error in the optimized model, albeit not necessarily a smaller geometrical error. This is done by generating a set of per-vertex weights that are used to scale the errors measured by the reduction algorithm, hence preserving areas with higher weights. The final optimized meshes produced by using this method is found to be subjectively closer to the original 3D asset than their non-weighed counterparts, and if the input meshes conform to certain criteria this method is well suited for inclusion in a fully automatic mesh decimation pipeline

Glioblastoma multiforme (GBM) is among the most aggressive and mortal cancers of the central nervous system. Maximal safe surgical resection, followed by radiotherapy accompanied with chemotherapy is the standard of care for GBM patients. Despite this intensive treatment with conventional approaches, the management of GBM remains poor. The infiltrative nature of cancer cells makes the complete tumour removal by surgery virtually impossible. In addition, the blood-brain barrier’s (BBB) lack of permeability limits the number of effective chemotherapy drugs for GBM. Temozolomide (TMZ) is the most widely used chemotherapeutic agent for GBM because of its ability to pass the BBB. However, high systemic doses required to achieve brain therapeutic level, resulting in numerous side effects. The recurrence of GBM is almost inevitable due to the aforementioned shortcomings of conventional methods of treatment. Therefore, a great deal of effort has been focused on the development of new treatment methods capable of providing a high concentration of chemotherapy drug at the tumour site. Microspheres made from biodegradable polymers hold great potential to keep the chemotherapeutic agent intact within the carrier and locally deliver the drug over an extended period. However, the encapsulation of amphiphilic drug molecules such as TMZ within poly (d, l-lactide-co-glycolide) (PLGA) microspheres with conventional emulsion methods, oil-in-water (o/w), water-in-oil-in-water (w/o/w), is a major challenge. The extremely low encapsulation efficiencies obtained for TMZ-loaded PLGA microspheres using the aforementioned techniques (<7%) hampers the ability to scale up this process. Additionally, the injected microspheres to the tumour site tend to dislocate due to the cerebral flow which reduces the effectiveness of this localized drug delivery strategy. This study has focused on the development of a 3D bioprinted hydrogel-based mesh containing TMZ-loaded PLGA microspheres with high encapsulation efficiency (GlioMesh). To accomplish this, oil-in-oil (o/o) emulsion solvent evaporation technique was used to prepare PLGA microspheres loaded with TMZ. The poor solubility of TMZ in the external oil phase, liquid paraffin, resulted in obtaining encapsulation efficiencies as high as 61%. We then used the 3D bioprinting technology to embed TMZ-loaded PLGA microspheres into an alginate mesh. This provides the advantage of immobilizing the microspheres at the tumour site. Additionally, the flexibility and porosity of 3D bioprinted mesh allow for easy implantation and nutrients transportation to the brain tissue. The incorporation of polymeric microspheres within alginate fibres led to achieving an extended release of TMZ over 50 days. The functionality of GlioMesh in inducing cell cytotoxicity was evaluated by performing in vitro cell viability tests on U87 human glioblastoma cells. Higher cytotoxic effects were observed in the case of treatment with GlioMesh compared to the free drug because of the sustained release properties of our mesh. These data suggest that GlioMesh holds great promise to be used as an implant in the treatment of GBM. / Graduate / 2019-04-19

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14599号 / 工博第3067号 / 新制||工||1456(附属図書館) / 26951 / UT51-2009-D311 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 大西 有三, 教授 間瀬 肇, 准教授 西山 哲 / 学位規則第4条第1項該当

In recent years, wireless mesh networking has attracted a growing interest due to its inherent flexibility, scalability, and reliability. The IEEE 802.16 standard, commonly known as worldwide interoperability for microwave access (WiMAX), is the latest technology that enables broadband wireless access over long distances. WiMAX, which emerges as a wireless alternative to cable and digital subscriber line (DSL), is an ideal candidate to serve as the infrastructure for large scale wireless mesh networks. This thesis focuses on the quality of service (QoS) provisioning techniques in WiMAX-based metropolitan area mesh networks. We study the connection admission control (CAC) and routing issues in the design and operation of wireless multihop mesh networks. We propose a joint CAC and routing scheme for multiple service classes with the objective to maximize the overall revenue from all carried connections. Connection-level QoS constraints such as handoff connection dropping probability can be guaranteed within a threshold. Multiple service classes can be prioritized by imposing different reward rates. We apply optimization techniques to obtain the optimal CAC policies. The optimality criterion is the long-run average reward. We demonstrate that the proposed scheme can the maximum revenue obtainable by the system under QoS constraints. We show that the optimal joint policy is a randomized policy, i.e., connections are admitted to the system with some probabilities when the system is in certain states. Simulation results illustrate that the proposed scheme meets our design goals and outperforms the existing scheme. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Recent advances in Wireless Mesh Networks (WMNs) have overcome the drawbacks of traditional wired networks and wireless ad hoc networks. WMNs will play a leading role in the next generation of networks, and the question of how to provide smooth mobility for WMNs is the driving force behind the research. The inherent characteristics of WMNs, such as relatively static backbones and highly mobile clients, require new handoff management solutions to be designed and implemented. This thesis first presents our research work on handoff management schemes in traditional WMNs. In general, a handoff process includes two parts, the MAC layer handoff and the network layer handoff. For the MAC layer handoff, a self-configured handoff scheme with dynamic adaptation is presented. Before the mobile node starts the probe process, it configures parameters for each channel to optimize the scan process. Moreover, a fast authentication scheme to reduce authentication latency for WiFi-based mesh networks is introduced. A tunnel is introduced to forward data packets between the new access router and the original reliable access router to recover data communication before the complete authentication process is finished. To minimize the network layer handoff latency, a hybrid routing protocol for forwarding packets is proposed: this involves both the link layer routing and the network layer routing. Based on the hybrid routing protocol, both intra-domain and inter-domain handoff management have been designed to support smooth roaming in WMNs. In addition, we extend our work to Vehicular Mesh Networks (VMNs). Considering the characteristics of VMNs, a fast handoff scheme is introduced to reduce handoff latency by using a multi-hop clustering algorithm. Using this scheme, vehicle nodes are divided into different multi-hop clusters according to the relative mobility. Some vehicle nodes are selected as assistant nodes; and these assistant nodes will help the cluster head node to determine the next access router for minimizing handoff latency. Extensive simulation results demonstrate that the proposed scheme can reduce handoff latency significantly.

When a shock interacts with a bubble having a different density than the environment or medium, the interaction causes compression and deformation of the bubble and generation of a vortex pair. Later, secondary vortices appear causing enhanced mixing. The enhanced mixing induced by the shock bubble interactions is particularly of interest in supersonic combustion and detonation. The Wavelet Adaptive Multi-resolution Representation (WAMR) method is particularly suitable for challenging continuum physics problems like shock bubble interaction, which has strong multi-scale character. This method provides an efficient strategy to create a dynamically adaptive spatial grid and to obtain a verified solution. Since the wavelet amplitude provides a first-hand estimate of the local error at each point, the method is able to efficiently capture a wide spectrum of spatial scales by dynamically changing the adaptive grid. Highly resolved computations are done only in the regions where abrupt transition occurs. In this work a detailed investigation of Shock Bubble Interaction (SBI) is carried out using shocks having Mach numbers from 1.2 to 3 for helium, nitrogen and krypton bubbles. Simulations carried out using WAMR method were used to analyze the effects of Mach number and density contrast on the shape, location and velocity of the bubble as well as vorticity and pressure in the flow field.

Das Ziel dieser Forschungsarbeit ist die Bestimmung charakteristischer aerodynamischer Koeffizienten im Schwebeflug mit Hilfe von Strömungssimulationen. Diese Koeffizienten werden für eine modellbasierte Regelung eines vollaktuierten Multikopters benötigt. Für die Simulationen wird aufbauend auf vorangegangenen Arbeiten ein ‚Sliding-mesh‘-Modell optimiert und einem ‚Overset-mesh‘-Modell gegenübergestellt. Die Verfahren werden anhand von Mess- sowie Referenzdaten hinsichtlich ihrer Rechenzeit und Genauigkeit verglichen. Die Messdaten werden im Rahmen dieser Arbeit ausgewertet. Die Referenzdaten stammen aus älteren Untersuchungen. Das ‚Overset-mesh‘-Verfahren liefert bei viermal höherer Rechenzeit gleichwertige adäquate Ergebnisse. Aus diesen Gründen werden anknüpfende Untersuchungen des Zeitverhaltens der Rotorschubkraft bei Drehzahländerungen mit dem ‚Sliding-mesh‘-Modell durchgeführt. Es wird beobachtet, dass die Schubkraft innerhalb der Simulation den Messdaten bei Drehzahlsprüngen vorauseilt.:1 Einleitung 1.1 Motivation 1.2 Zielsetzung und Aufbau der Arbeit 2 Theoretische Grundlagen 2.1 Strömungsmechanik 2.1.1 Grundgleichungen 2.1.2 Zusätzliche Gleichungen 2.1.3 Navier-Stokes-Gleichungen 2.1.4 Laminare und turbulente Strömungen 2.1.5 Grenzschicht 2.2 Numerische Strömungsmechanik 2.2.1 Numerische Diskretisierung 2.2.2 Numerische Lösungsmodelle 2.2.3 Turbulenzmodelle 2.3 Rotorströmungen 2.3.1 Strahltheorie 2.3.2 Numerische Rotorsimulation 3 Stand der Technik 3.1 Motivation 3.2 Rotorströmung 3.3 Aeroelastizität 3.4 Nachlaufströmung 4 Umsetzung 4.1 Modellbildung 4.1.1 ‚Sliding-mesh‘-Verfahren 4.1.2 ‚Overset-mesh‘-Verfahren 4.2 Validierung 4.2.1 ‚Sliding-mesh‘-Verfahren 4.2.2 ‚Overset-mesh‘-Verfahren 4.3 Modifikationen 4.3.1 ‚Sliding-mesh‘-Verfahren 4.3.2 ‚Overset-mesh‘-Verfahren 4.4 Auswertung 4.4.1 ‚Sliding-mesh‘-Verfahren 4.4.2 ‚Overset-mesh‘-Verfahren 5 Messaufbau und Messauswertung 5.1 Messaufbau 5.2 Messauswertung 5.2.1 Schubkraftverlauf 5.2.2 Drehmomentenverlauf 6 Zeitverhalten 6.1 Modellbildung 6.2 Auswertung Schubkraftverlauf 6.2.1 Drehzahlsprung 1 6.2.2 Drehzahlsprung 2 7 Zusammenfassung und Ausblick 7.1 Zusammenfassung 7.2 Ausblick