Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Wing construction.
Dissertationen zum Thema „Wing construction“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Dissertationen für die Forschung zum Thema "Wing construction" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Rahman, Selma, und Anujan Ranganathan. „Conceptual design and construction of a UAV wing structure“. Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276681.
Der volle Inhalt der QuelleAnnotation:
This report presents the design of the wing structure for a UAV called Skywalker X8. A model of the UAV was given and analyzed to design a wing box structure that is twice the size of the current model, with "greener" technology and lightweight materials. The loads that act upon the UAV were simulated and thereafter analyzed with the help of the CFD program called Star CCM+. Modifications on the CAD model and the FEM simulations were performed in Siemens NX. Eight different combinations were tested from the following five materials: CFRP (carbon fiber reinforced polymer), LDPE (low density polyethylene), polyethylene, polypropylene, and balsa wood. The results that best fit the requirements given was the combination of polypropylene as the wing skin and balsa as the honeycomb structure. This design weighed 3.576 kg and had the following stresses: 0.671 MPa, 0.340 MPa, 1 MPa, and 4 MPa for the angle of attacks at 1,2,3, and 6 degrees respectively. A modification of the trailing edge, which was the implementation of a Gurney flap, was made to see if it improved the lift-to-drag ratio, but unfortunately it did not so it was not developed further.Denna rapport kommer att presentera en design och konstruktion av höger vinge på en drönar-modell (UAV), X8 Skywalker. CAD modellen var given och användes vid de aerodynamiska och hållfasthets simuleringarna. Syftet med projektet var att konstruera vingen utifrån dessa perspektiv för vingen i fördubblad storlek, med "grönare" teknik i åtanke. Belastningarna som verkar på drönaren beräknades med hjälp av ett program, Star CCM+, som behandlar CFD-simuleringar. Redigering av CAD modellen och FEM-analyserna utfördes med hjälp av Siemens NX. Åtta olika kombinationer av 5 olika material testades, vilket är de följande: CFRP (carbon fibre reinforced polymer), LDPE (low density polyethylene), polyeten, polypropylen och balsa. Resultaten som uppfyller kraven bäst var polypropylen som vingens ytterhölje och balsa som honeycomb-strukturen. Denna konstruktion vägde totalt 3.576 kg och hade följande von Mises spänningar: 0.671 MPa, 0.340 MPa, 1 MPa och 4 MPa för angreppsvinklarna 1, 2, 3 respektive 6 grader. En modifiering av trailing edge gjordes för att se om det gav en förbättring av lift-to-drag ratio. Då den inte gav en önskad förändring så utvecklades den inte vidare.
2
Skelton, Ian R. „Innovation in construction techniques for tall buildings“. Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19637.
Der volle Inhalt der QuelleAnnotation:
The skyline of many 'world cities' are defined and punctuated by tall buildings. The drivers for such dominant skylines range from land scarcity and social needs; high real estate values; commercial opportunity and corporate demand, through to metropolitan signposting. This fascination with tall buildings started with the patrician families who created the 11th Century skyline of San Gimignano by building seventy tower-houses (some up to 50m tall) as symbols of their wealth and power. This was most famously followed in the late 19th Century with the Manhattan skyline, then Dubai building the world's highest building, then China building some eighty tall buildings completed in the last 5 years, then UK building Europe's highest tower, the Shard and finally back to Dubai, planning a kilometre tall tower, potentially realising Ludwig Mies van der Rohe's 'Impossible Dream' of the 1920's and Frank Lloyd Wright's 1956 'Mile High Illinois'. This ambition to build higher and higher continues to challenge the Architects, Engineers and Builders of tall buildings and is expected to continue into the future. The tall building format is clearly here to stay.
3
Chabada, Martin. „Návrh křídla letounu UAV v kategorii do 600 kg“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442849.
Der volle Inhalt der QuelleAnnotation:
The main aim of the this diploma thesis is the wing design of the UAV aircraft, including the appropriate material choice, calculation of the wing load and also strength analysis. Other goals include the design of the location and volume of fuel tanks, as well as the design of wingspan reduction after landing.
4
Kao, Pi-Jen. „Efficient methods for integrated structural-aerodynamic wing optimum design“. Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54211.
Der volle Inhalt der QuelleAnnotation:
The dissertation is focused on the large computational costs of integrated multidisciplinary design. Efficient techniques are developed to reduce the computational costs associated with integrated structural-aerodynamic design. First efficient methods for the calculations of the derivatives of the flexibility matrix and the aerodynamic influence coefficient matrix are developed. An adjoint method is used for the flexibility sensitivity, and a perturbation method is used for the aerodynamic sensitivity. Second a sequential optimization algorithm that employs approximate analysis methods is implemented. Finally, a modular sensitivity analysis, corresponding to the abstraction of a system as an assembly of interacting black boxes, is applied. This method was developed for calculating system sensitivity without modifying disciplinary black-box software packages. The modular approach permits the calculation of aeroelastic sensitivities without the expensive calculation of the derivatives of the flexibility matrix and the aerodynamic influence coefficient matrix.Ph. D.
5
Strauch, Gregory J. „Integrated multi-disciplinary design of a sailplane wing“. Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45660.
Der volle Inhalt der QuelleAnnotation:
The objective of this research is to investigate the techniques and payoffs of integrated aircraft design. Lifting line theory and beam theory are used for the analysis of the aerodynamics and the structures of a composite sailplane wing. The wing is described by 33 - 34 design variables which involve the planform geometry, the twist distribution, and thicknesses of the spar caps, spar webs, and the skin at various stations along the wing. The wing design must satisfy 30 â 31 aeroelastic, structural, aerodynamic, and performance constraints.
Two design procedures are investigated. The first, referred to as the iterative, sequential procedure, involves optimizing the aerodynamic design for maximum average cross-country speed at E1 constant structural weight, and then optimizing the the structural design of the resulting wing geometry for minimum weight. This value is then used in another aerodynamic optimization, and the process continues iteratively until the weight converges. The other procedure, the integrated one, simultaneously optimizes the aerodynamic and the structural design variables for either maximum average cross-country speed or minimum weight.
The integrated procedure was able to improve the value of the objective function obtained by the iterative procedure in all cases. This shows The objective of this research is to investigate the techniques and payoffs of integrated aircraft design. Lifting line theory and beam theory are used for the analysis of the aerodynamics and the structures of a composite sailplane wing. The wing is described by 33 - 34 design variables which involve the planform geometry, the twist distribution, and thicknesses of the spar caps, spar webs, and the skin at various stations along the wing. The wing design must satisfy 30 â 31 aeroelastic, structural, aerodynamic, and performance constraints. Two design procedures are investigated. The first, referred to as the iterative, sequential procedure, involves optimizing the aerodynamic design for maximum average cross-country speed at E1 constant structural weight, and then optimizing the the structural design of the resulting wing geometry for minimum weight. This value is then used in another aerodynamic optimization, and the process continues iteratively until the weight converges. The other procedure, the integrated one, simultaneously optimizes the aerodynamic and the structural design variables for either maximum average cross-country speed or minimum weight.
The integrated procedure was able to improve the value of the objective function obtained by the iterative procedure in all cases. This shows that definite benefits can be gained from taking advantage of aerodynamic/structural interactions during the design process.
Master of Science
6
Polen, David M. „Integrated aerodynamic-structural design of a subsonic, forward- swept transport wing“. Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/46059.
Der volle Inhalt der QuelleAnnotation:
The introduction of composite materials and the ability to tailor these materials to improve aerodynamic and structural performance is having a distinct effect upon aircraft design. In order to optimize the efficiency of the design procedure, a design process which is more integrated than the traditional approach is required. Currently the utilization of such design procedures produces enormous computational costs. An ongoing effort to reduce these costs is the development of efficient methods for cross-disciplinary sensitivities and approximate optimization techniques.
The present research concentrates on investigating the integrated design optimization of a subsonic, forward-swept transport wing. A modular sensitivity approach for calculating the cross-sensitivity derivatives is employed. These derivatives are then used to guide the optimization process. The optimization process employed is an approximate technique due to the complexity of the analysis procedures. These optimization results are presented and the impact of the modular technique is discussed.
Master of Science
7
Dewitz, Michael B. „The effect of a fillet on a wing/body junction flow“. Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43843.
Der volle Inhalt der Quelle
8
Brooks, W. G. „The design, construction and test of a postbuckled, carbon fibre reinforced plastic wing box“. Thesis, Cranfield University, 1987. http://hdl.handle.net/1826/3292.
Der volle Inhalt der QuelleAnnotation:
A postbuckled, carbon fibre reinforced plastic (CFRP)
wing box has been designed, manufactured and tested
for an aerobatic light aircraft, the Cranfield Al.
Methods of analysis have been evaluated including:
i) Non-linear finite element analysis for the
prediction o-f panel postbuckling.
ii) A simpler technique based on an effective
width method. This forms the core of a design program,
'oPTIMIST'. It predicts buckling loads, postbuckled
reduced stiffness and overall column failure of
co-cured hat stiffened panels. It then optimises the
con-Figuration of a box beam for minimum weight.
iii) The use of the effective width method allied
to a large scale, linear finite element analysis.
The work includes the development of a new method
o-F construction for composite box structures. The wing
skin sti-Ffeners and rib flanges are co-cured
together. Integral slotted Joint features are formed
in each part. The structure is then adhesively bonded
together. A full description of the manufacture o-F the
wing box is included.
The structure was also tested in a specially
designed rig. It was tested to ultimate design loads
in:
i) Positive bending to 13.33.
ii) Negative bending to -96.
iii) Pure torsion resulting from full aileron
load.
iv) Torsion with 96 bending.
The compression panels were seen to postbuckle and
recover in each load case. Results are compared with
theory, and with the original aluminium Al wing. The
structure is 257. lighter than its aluminium
counterpart.
Finally, suggestions are made for possible areas
of further research.
9
Unger, Eric Robert. „Computational aspects of the integrated multi-disciplinary design of a transport wing“. Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42125.
Der volle Inhalt der QuelleAnnotation:
Past research at this university has proven the feasibility of the multi-disciplinary design of a complex system involving the complete interaction of aerodynamics and structural mechanics. Critical to this design process, is the ability to accurately and efficiently calculate the sensitivities of the involved quantities (such as drag and dynamic pressure) with respect to the design variables. These calculations had been addressed in past research, but it was felt that insufficient accuracy had been obtained. The focus of this research was to improve the accuracy of these sensitivity calculations with a thorough investigation of the computational aspects of the problem. These studies led to a more complete understanding of the source of the errors that plagued previous results and provided substantially improved sensitivity calculations.
Additional research led to an improvement in the aerodynamic-structural interface which aided in the accuracy of the sensitivity computations. Furthermore, this new interface removed discontinuities in the calculation of the drag which the previous model tended to yield. These improvements were made possible with the application of shape functions in surface deflection analysis, instead of the previous ‘zonal’ approach. Other factors which led to accuracy improvements were changes to the aerodynamic model and the paneling scheme.
Final studies with the optimization process demonstrated the ability of the improved sensitivities to accurately approximate the design problem and provided useful results. Additional studies on the optimization process itself provided information on move limit restrictions and various constraint problems.Master of Science
10
Rohl, Peter Jurgen. „A multilevel decomposition procedure for the preliminary wing design of a high-speed civil transport aircraft“. Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/11827.
Der volle Inhalt der Quelle
11
Ha, Kwangtae. „A Combined Piezoelectric Composite Actuator and Its Application to Wing/Blade Tips“. Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7575.
Der volle Inhalt der QuelleAnnotation:
A novel combined piezoelectric-composite actuator configuration is proposed and analytically modeled in this work. The actuator is a low complexity, active compliant mechanism obtained by coupling a modified star cross sectional configuration composite beam with a helicoidal bimorph piezoelectric actuator coiled around it. This novel actuator is a good candidate as a hinge tension-torsion bar actuator for a helicopter rotor blade flap or blade tip and mirror rotational positioning. In the wing tip case, the tip deflection angle is different only according to the aerodynamic moment depending on the hinge position of the actuator along the chord and applied voltage because there is no centrifugal force. For an active blade tip subject to incompressible flow and 2D quasi steady airloads, its twist angle is related not only to aerodynamic moment and applied voltage but also to coupling terms, such as the trapeze effect and the tennis racquet effect. Results show the benefit of hinge position aft of the aerodynamic center, such that the blade tip response is amplified by airloads. Contrary to this effect, results also show that the centrifugal effects and inertial effect cause an amplitude reduction in the response. Summation of these effects determines the overall blade tip response. The results for a certain hinge position of Xh=1.5% chord aft of the quarter chord point proves that the tip deflection target design range[-2,+2] can be achieved for all pitch angle configurations chosen.
12
Tai, Jimmy C. M. „A multidisciplinary design approach to size stopped rotor/wing configurations using reaction drive and circulation control“. Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13460.
Der volle Inhalt der Quelle
13
Masango, Thubalakhe Patrick. „Condition monitoring of a wing structure for an unmanned aerial vehicle (UAV)“. Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2384.
Der volle Inhalt der QuelleAnnotation:
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015.Currently non-destructive testing techniques for composite aircraft structures are disadvantaged when compared to online Structural Health Monitoring (SHM) systems that monitor the structure while in-service and give real time data. The present research work looks at developing a protocol for online structural health monitoring of a UAV wing structure using PVDF film sensors, especially including the monitoring of structural changes caused by defects. Different types of SHM techniques were studied in relation to carbon fibre composites. Laminate composite make-up and manufacturing process was investigated and vacuum infusion process was used to manufacture the samples that resemble the Guardian II wing structure, then the three-point bending test was used to determine the material properties. Digital Shearography was employed as a stationery non-destructive technique to determine the sensor to structure attachment, type and position of defects that affect the state of performance. Finite Element Analysis (FEA) was done using ANSYS Workbench which served as a modelling tool using a drawing imported from Solid-works. Experimental investigation was done using PVDF sensor embedded on the surface of the sample in a cantilever setup and a vertical Vernier scale to measure the deflection due to impact and vibration loading. A Fluke-View oscilloscope was used as a data logger when the measurement of the output voltage and the natural frequency were recorded. The techniques of using FEA and experimental investigation were then compared. The findings of this study showed that the PVDF sensor is suitable for condition monitoring of a UAV wing structure.
14
Huang, Ximing. „Structural optimization and its interaction with aerodynamic optimization for a high speed civil transport wing“. Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40132.
Der volle Inhalt der QuelleAnnotation:
A variable-complexity design strategy with combined aerodynamic and structural optimization procedures is presented for the high speed civil transport design (HSCT). Variable-complexity analysis methods are used to reduce the computational expense. A finite element-model based structural optimization procedure with flexible loads is implemented to evaluate the wing bending material weight. Static aeroelastic effects, evaluated through the comparison of rigid and flexible wing models, are found to be small in the HSCT design. The results of structural optimization are compared with two quasi-empirical weight equations. Good correlation is obtained between the structural optimization and one of the weight equations. Based on this comparison, an interlacing procedure is developed to combine both the simple weight equations and structural optimization in the HSCT design optimization, at modest computational cost. HSCT designs based on the interlacing procedure reveal that the aerodynamic optimizer may take advantage of weaknesses in weight equation. However, the optimizer may be unable to escape the local minimum due to the noisy of aerodynamic response and the lack of derivative information for the interlacing procedure.Ph. D.
15
Cisternino, Stefano. „The Construction and Destruction of “the other”The Influence of Right-wing Populist Rhetoric on Xenophobic Hate Crimes“. Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-418232.
Der volle Inhalt der QuelleAnnotation:
Today, two phenomena are growing; the constant increase in xenophobic hate crimes and the rampant presence of political and media representatives engaged in right-wing populist rhetoric aimed at defending the people from all threats. The question of how right-wing populist rhetoric influences the occurrence of these violent acts has only been addressed indirectly and partially in the academic world. This thesis tries to fill this gap, by proposing the following argument: right-wing populist rhetoric, through a process of continuous growth and affirmation, gradually creates an enemy who is ethnically “different” from the “native” people, leading to a social reaction and therefore to a consequent increase in xenophobic hate crimes. In order to verify this claim, an analysis of two periods of Italian history is conducted by means of Process Tracing. A primary case (1935-1939), focused on the Fascist Party and Mussolini with respect to two ethnic targets: Ethiopians and Jews. A secondary case (2013-2016), focused on the Lega Nord party and Salvini with respect to immigrants. The empirical results achieved provide good general support and suggest the need for further research, in order for countermeasures to be enacted by policymakers to avoid history repeating itself.
16
Ajaj, Rafic Mohammad. „Design, modelling and optimisation of morphing structures for medium altitude long endurance UAVs“. Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678283.
Der volle Inhalt der Quelle
17
Chan, Yiu-hung. „The construction of sexuality of Hong Kong cinema in the 90's“. Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20454806.
Der volle Inhalt der Quelle
18
McBride, William M. „The effect of wing wall geometry and well deck configuration on the stability characteristics of amphibious landing ship dock (LSD) class ships“. Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/101234.
Der volle Inhalt der QuelleAnnotation:
Amphibious ships, configured with floodable well decks, present a unique challenge to the Ship Design Team to incorporate maximum troop, cargo and vehicle capacity, along with sufficient well deck size, to facilitate efficient operation of LCAC (Landing Craft Air Cushion) and other amphibious assault craft in support of power projection operations. Analysis of the various LSD 49 Class alternative designs, revealed significant variance in the stability limits for each design. These variations appeared to be directly attributable to wing wall size, as well as to the geometry of the well deck. In order to better understand the effect of these items, and to develop guidelines for future design efforts, this study concentrated on evaluating the stability limitations for various combinations of beam, well deck configuration, and wing wall size using an LSD 49 Class proposed hull form. The results indicated that the most significant parameter affecting the stability of the LSD 49 Class is the height of the well deck above the baseline. The higher the well deck, the smaller the loss of waterplane inertia caused by the entrance of flooding water into the well deck compartment. For lower well decks, the loss of waterplane inertia is more critical at smaller values of beam, but becomes less critical at the upper values of beam considered. In these cases, off-center wing wall flooding becomes more critical, and it is more advantageous to devote larger percentages of beam to the well deck compartment.M.S.
19
Sadovský, Hynek. „Návrh uzlu křídlo-trup kompozitního letounu“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232005.
Der volle Inhalt der QuelleAnnotation:
This master's thesis deals with design, strength calculation and technological solution of wing-fuselage joint for composite four-seater aeroplane certificated by CS-23. Design is focused on optimal space utilization, low weight and simple manufacturing and assembly. Main output is technical documentation consisting of drawings and technological lay-ups. Conceptual design was chosen after analysis and weight estimation. With strenght calculation for composite materials it was possible to design composition of primary parts and also specify manufacture processes. Assigment was solved by unusuall conceptual design, which claims higher precision manufacturing, but it saves weight.
20
Karlsson, Lotta. „Construction of inflected wings“. Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-26095.
Der volle Inhalt der Quelle
21
Krajnovic, Tamara. „Multi-level governance and wind power construction in Sweden : A case study of Norrköping and a current wind power construction plan“. Thesis, Stockholms universitet, Statsvetenskapliga institutionen, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-192866.
Der volle Inhalt der QuelleAnnotation:
This case study focuses on wind power development in Norrköping using a multi-level governance approach. The aim is to examine the wind power decision-making process from the state to Norrköping municipality and to identify other factors that impact wind power development in the area. A textual analysis comparing national political party platforms and local parties' official stances and interviews has been used to achieve this study's goal. The study shows that the decision-making in vertical multi-level governance is both bottom-up and top-down. It also sheds light on a significant role the Swedish Armed Forces play in this process as an external actor. The study concludes that vertical multi-level governance, including municipal veto, although an important factor, needs to be complemented with external factors to see how it affects wind power development in Norrköping.
22
Van, Zyl Willem Sternberg. „Concrete wind turbine towers in Southern Africa“. Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96021.
Der volle Inhalt der QuelleAnnotation:
Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Exponential growth of the global wind turbine market has led to a significant increase in the capacity of wind turbine generators. Modern turbines require higher support structures as higher wind speeds combined with longer blades are necessary to increase their generating capacity. The standard 80-90 m tower is thus not economically viable anymore. Transportation logistics of large steel towers has led to concrete towers becoming a viable option. There are currently no design codes dealing exclusively with the design of concrete wind turbine towers. The aim of this project is to investigate and highlight important aspects of the design process of a normally reinforced high strength concrete wind turbine tower. The tower was designed using nonlinear finite element modelling as a design tool to accurately design the tower for various loads and load cases. An analytical design method was developed that can be used in the preliminary design stage. Finally, the importance of the soil-structure interaction was investigated through a sensitivity analysis. It was found that the formation of cracks greatly affected the stiffness of the structure and that the reduction in stiffness increased the deflection significantly. It was also found that a structure that has sufficient strength to resist the ULS loads may not necessarily comply with the maximum deflection limit for the SLS. The concrete strength class required was not only determined by the maximum compression stress the concrete would experience, but also by the stiffness required to ensure that the tower frequency is within the turbine’s working frequency. The dynamic behaviour of the tower was also affected by the formation of cracks. The fundamental frequency of the tower was reduced by 46% after the SLS loads were applied. It was found that the soil preparation for the foundation plays a vital role in ensuring that the tower frequency is not reduced to a level where it falls outside the turbine working frequency.
AFRIKAANSE OPSOMMING: Die eksponensiële groei van die globale wind turbine mark het gelei tot ʼn beduidende toename in die opwekkingskapasiteit van wind turbine kragopwekkers. Moderne turbines benodig hoër ondersteuningstrukture om hulle opwekkingskapasiteit te verhoog en daarom is die standaard 80-90 m toring nie meer geskik nie. Die vervoer logistiek van groot staal torings het daartoe gelei dat beton torings ʼn lewensvatbare opsie geword het. Daar is huidiglik geen ontwerpkodes wat uitsluitlik handel met die ontwerp van beton wind turbine torings nie. Die doel van hierdie projek is om die ontwerp proses van ʼn bewapende hoë sterkte beton wind turbine toring te ondersoek en belangrike aspekte uit te lig. Die toring word ontwerp deur ʼn nie-liniêre eindige element model te gebruik as ʼn ontwerp hulpmiddel, om die toring akkuraat te ontwerp vir verskeie laste en lasgevalle. ʼn Analitiese ontwerpmetode is ontwikkel wat gebruik kan word in die voorlopige ontwerpfase. Laastens is die grond-struktuur interaksie ondersoek deur ʼn sensitiwiteitsanalise. Daar is gevind dat die vorming van krake die styfheid van die struktuur aansienlik beïnvloed en dat die vermindering in styfheid die defleksie beduidend vermeerder. Daar is ook gevind dat ʼn struktuur wat voldoende sterkte het om die uiterste lastoestande te weerstaan, nie noodwendig voldoen aan die maksimum defleksiegrens vir die diens lastoestande nie. Die beton sterkte klas wat benodig is, is nie net bepaal deur die maksimum druk spanning wat die beton sal ondervind nie, maar ook deur die styfheid wat vereis word om te verseker dat die toring se frekwensie binne die turbine se werksfrekwensie val. Die dinamiese gedrag van die toring is ook beïnvloed deur die vorming van krake. Die fundamentele frekwensie van die toring is verlaag met 46% nadat die diens lastoestande toegepas is. Daar is gevind dat die grond voorbereiding vir die fondasie ʼn belangrike rol speel om te verseker dat die toring se frekwensie nie verlaag word tot ʼn vlak waar dit buite die turbine se werksfrekwensie val nie.
23
Lee, Donghoon. „Multi-flexible-body analysis for applications to wind turbine control design“. Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04052004-180040/unrestricted/lee%5Fdonghoon%5F200312%5Fphd.pdf.
Der volle Inhalt der Quelle
24
Canovi, Magali. „Identity construction and its influence on wine tourism diversification decisions : case study of family wineries in Langhe, Italy“. Thesis, University of Chester, 2017. http://hdl.handle.net/10034/621029.
Der volle Inhalt der QuelleAnnotation:
The aim of this thesis is to examine family wineries’ wine tourism diversification decisions in terms of wine producers’ self-constructions. The focus lies on understanding which motives drive family businesses’ decisions to engage in diversification. A case study approach is adopted, using the Italian wine region of Langhe in Piedmont. The dominant debates within the current literature have primarily concentrated on the economic-social dichotomy in relation to diversification decisions. It has been argued that diversification decisions are predominantly economically driven, highlighting the importance of profit maximisation and risk reduction. This thesis highlights the limitations of the economic-social dichotomy approach and argues for the need to take the social context into account when examining the decision-making process. An interpretivist approach to research is adopted in order to extend current understandings of family businesses and their motives underlying diversification decisions. In line with the interpretivist perspective, this thesis uses discourse analysis (DA) as a methodological approach for analysing and interpreting wine producers’ accounts. The findings reveal that by engaging in discourse about wine tourism diversification, wine producers construct a distinctive, coherent and desired sense of self, which in turn influences family wineries’ decisions to diversification. In this instance, the concept of identity formation plays a central role in explaining family wineries’ motives for diversification. Linking wine producers’ motives for diversification to their self-constructions provides a new insight into how family businesses engage in decision-making. Wine producers’ discourses reveal that their decision-making processes are inextricably linked to sustaining a positive sense of self. Decisions are not only taken to achieve economic goals, but are likely to be influenced by deeper motives, notably wine producers’ identity constructions. The main contribution of this thesis is that it advances understanding of family businesses’ decisionmaking processes by developing a multi-layered conceptual framework to go beyond the economic-social dichotomy in order to reveal wine producers’ semi-conscious and unconscious motives for diversification.
25
Korytář, Jan. „Aspekty ovlivňující trendy v technologii provozu letadlové techniky civilního letectví“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443765.
Der volle Inhalt der QuelleAnnotation:
The aim of the work is a general description of the effects on air traffic and aircraft. The first part of the work is devoted to a brief description of the development of individual technical parameters and performance of aircraft from the 1920s to the present with an assessment of the effects. The second part of the work is about the influence of current requirements and the third part is a general view of the future development of construction and technology for more economical and environmentally friendly air transport
26
Gogas, Kyriakos. „Design of a robust speed and position sensorless decoupled P-Q controlled doubly-fed induction generator for variable-speed wind energy applications“. Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99762.
Der volle Inhalt der QuelleAnnotation:
Wind energy is a relatively young but rapidly expanding industry. In order for wind generation to be cost effective, it must produce energy at a minimum cost per dollar of investment. Performance characteristics such as power output versus wind speed must be optimized in order to compete with other energy sources. Also, if the utility uses wind power for a part of its generation, the output power of these turbines must have the same high quality and reliability when it enters the utility grid. The ability to vary operating speed is important in wind generation because it allows for an optimization of the transfer of power from the wind to the turbine shaft. Doubly-fed induction generators (DFIG) are an interesting solution for variable-speed systems with limited variable speed range, and are typically used in wind energy conversion systems.The objectives of this thesis are to implement a decoupled P-Q control of a DFIG that does not rely on mechanical sensors and to design a speed and position sensorless algorithm that is robust to variations of the values of the machine parameters. The sensorless DFIG control algorithm presented in this thesis is based on a modified phasedlock loop with an improved positioning algorithm. With the measured stator voltages, stator and rotor currents, the speed and position of the DFIG are estimated. The speed is estimated independent of machine parameters, which results in a significant improvement in speed control robustness to parameter variations. In addition, the algorithm avoids using differentiation, which significantly improves its immunity to noise and does not require the measurement of the rotor voltages. Also, it is shown that the positioning algorithm has an improved operation in generator mode. Although the accuracy of the positioning algorithm is depended on machine parameters; it is shown with the designed controller that the P-Q decoupled control is robust to changes of machine parameters. Theoretical and simulation results are validated on an experimental setup.
27
Nyström, Oskar. „FIRE SAFETY AND EVACUATION SECURITY IN WIND TURBINES“. Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-83289.
Der volle Inhalt der QuelleAnnotation:
I denna rapport sammanställs information om brandsäkerhet och utrymningssäkerhet i vindkraftverk för att dra slutsatser om hur säkerheten skulle kunna förbättras. Orsaken till att detta anses vara ett intressant område för studier är att det är en bransch som snabbt växer och som är extraordinärt ur en utrymningssynpunkt på grund av höjden på dagens kraftverk. Med hjälp av litteraturstudier, en enkät riktad till tekniker inom vindkraftsbransch och intervjuer av både personer inom bransch och från räddningsorganisationer så har information om ämnet samlats in. Med hjälp av personer med dessa mycket olika perspektiv på vindkraft och säkerhet så dras slutsatser om dagens läge och vad som skulle kunna förbättras ur en säkerhetskritisk synvinkel. Vid enkätstudien tillfrågades 32 personer som arbetar i vindkraftverk olika frågor som på ett eller annat sätt berör brand och säkerhet i deras arbetsmiljö. Resultaten från denna enkät tyder på att servicetekniker på kraftverken generellt sett känner sig förhållandevis trygga på sin arbetsplats, men tycker samtidigt att den går att förbättra ur en säkerhetsynpunkt. Något som tas upp är bland annat bristen på brandlarm och automatiska släcksystem i maskinhuset på kraftverken. Båda typer finns på en del kraftverk, men personal på anläggningarna vill i många fall se det på betydligt fler av verken. Utrymning verkar inte vara något som serviceteknikerna oroar sig för, men en rapport från Nanjing Tech Univeristy, RISE, Technical Univeristy of Denmark och Univeristy of Zilina tyder på att utrymning i händelse av brand kan vara problematiskt i vindkraftverk. I rapporten har linorna som är tänkt att användas som en del i utrymningen testats utifrån resultaten i en simulerad brand i maskinhuset. Vid simuleringen användes PyroSim för att simulera brandförlopp där temperaturer kunde tas fram vid olika tider. Dessa temperaturer och tider jämfördes sedan med antändningstemperatur för de linor som används vid utrymning. Resultatet visade att linorna antänds inom den tid som är tänkt för utrymning från vindkraftverket. Stämmer detta kan inte vinschning ses som en alternativ väg för utrymning i händelse av brand. Vid intervjustudien med räddningsorganisationer har fokus legat på släckning av vindkraftverk. De organisationer som deltagit har svarat väldigt lika på dessa frågor. På grund av höjden på kraftverken och den höga brandbelastning som oftast uppstår så har inga släckningsförsök vidtagits vid insatser i vindkraftverk. I stället har räddningsinsatserna fokuserats på att spärra av området kring kraftverket och försökt att minimera brandspridningen till omkringliggande område. Räddningsorganisationer med vindkraftsparker i sitt område verkar ha en god relation med ägare från branschen. Tillsammans utför de båda kontinuerligt övningar inom livräddning på kraftverken tillsammans med båda parter. Dessa övningar är dock inte på något sätt en förberedelse för livräddning vid brand i till exempel maskinhus, utan snarare fokuserade på livräddning vid annan olycka eller sjukdom. Slutsatserna från arbetet är att mer information skulle behövas för att helt kunna utvärdera om brandsäkerheten är tillräcklig i vindkraftverk. Den rapport från 2014 som visar på att utrustningen för vinschning ej tål brand är förvisso alarmerande, men enligt rapporten så krävs ytterligare undersökningar för att kunna dra några mer konkreta slutsatser. Mellan bransch och räddningsorganisationer tycks relationen vara god men de möjligheter som räddningsorganisationer har att släcka eller livrädda personer i brinnande kraftverk är mycket små. Detta medför att i princip allt ansvar inom brand- och utrymningssäkerhet ligger på branschen. Den mest uppenbara åtgärden skulle vara att ställa krav på installation av automatiska släcksystem och brandlarm. Detta är också det som många servicetekniker, vilka är den mest utsatta yrkesgruppen i sammanhanget, efterfrågar.
28
Rocha, Daniel. „RELIABILITY OF LIGHT-FRAME WOOD ROOF CONSTRUCTION UNDER EXTREME WIND LOADS“. MSSTATE, 2005. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07082005-125227/.
Der volle Inhalt der QuelleAnnotation:
Light-frame wood construction is frequently used in the U.S. High wind events, such as hurricanes, may cause severe damage to these structures by breaking the roof envelope. This study focuses on computing reliability indices of roof sheathing panels exposed to high wind events while considering a time and spatially varying wind load. A procedure is developed that links probabilistic and dynamic finite element analysis codes. The results show that a few critical panels are most susceptible to damage, while most panels have significantly higher reliability indices than previous studies based on simplified analyses have shown. By setting a target reliability index, panel nail spacing can be adjusted to provide a more uniform level of safety over the entire roof.
29
Huenefeld, Joshua. „A report on the effects of wind speed on timber construction“. Kansas State University, 2012. http://hdl.handle.net/2097/13606.
Der volle Inhalt der QuelleAnnotation:
Master of ScienceDepartment of Architectural Engineering
Kimberly Waggle Kramer
Main lateral force resisting systems (MLFRS) in timber buildings consist of two components: diaphragms and shear walls. Diaphragms are used to collect the shear induced by the lateral force at each of the levels. The shear is transferred from the diaphragms to the shear walls via plywood sheathing and connections. The shear walls transfer shear to the sill plate via plywood sheathing and then into the foundation via anchors. Two approaches for designing shear wall are: the segmented shear wall approach and the perforated shear wall approach. The segmented shear wall approach uses only full height segments to resist shear; each individual segment must be designed to resist the shear and overturning force induced by the lateral load. The perforated shear wall approach uses both full height segments and segments around openings to resist shear; the wall as a whole is used to resist shear and overturning forces induced by the lateral load. This report examines one-, two-, and three-story timber buildings located in three different wind regions: a) 115 mph, b) 140 mph, and c) 160 mph. This report presents the design process for the MLFRS components and a comparison of the designs for each of the buildings. The purpose of this report is to determine how the design changes depending on the magnitude of the lateral load, the height of the building, and the approach used to design the shear walls.
30
Poole, Sean Nichola. „Optimisation of a mini horizontal axis wind turbine to increase energy yield during short duration wind variations“. Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/7036.
Der volle Inhalt der QuelleAnnotation:
The typical methodology for analytically designing a wind turbine blade is by means of blade element momentum (BEM) theory, whereby the aerofoil angle of attack is optimized to achieve a maximum lift-to-drag ratio. This research aims to show that an alternative optimisation methodology could yield better results, especially in gusty and turbulent wind conditions. This alternative method looks at increasing the aerofoil Reynolds number by increasing the aerofoil chord length. The increased Reynolds number generally increases the e_ectiveness of the aerofoil which would result in a higher or similar lift-to-drag ratio (even at the decreased angle of attacked require to maintain the turbine thrust coe_cient). The bene_t of this design is a atter power curve which causes the turbine to be less sensitive to uctuating winds. Also, the turbine has more torque at startup, allowing for operatation in lower wind speeds. This research is assumed to only be applicable to small wind turbines which operated in a low Reynolds number regime (<500 000), where Reynolds number manipulation is most advantageous.
31
Capasso, Michael Anthony. „Construction and wind tunnel test of a 1/12th scale helicopter model“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA288487.
Der volle Inhalt der Quelle
32
Garcia, Jason S. „Design, Construction, and Characterization of the University of South Florida Wind Tunnel“. Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7294.
Der volle Inhalt der QuelleAnnotation:
Much of the aerosol research completed at the University of South Florida has revolved around evaluating industrial hygiene equipment and instrumentation in environmental chambers. Data collected during these studies has provided valuable baseline data on equipment and instrument performance under calm air conditions. A newly constructed wind tunnel now allows researchers to evaluate industrial hygiene instruments under moving air conditions. Because the wind tunnel is capable of producing wind velocities that a worker could encounter in the occupational setting, researchers may gain insight into instrument performance under simulated field conditions. Because aerosols can be introduced into the new wind tunnel testing section, researchers can also challenge industrial hygiene equipment and instrumentation with aerosols in sizes ranges that are of interest in public health.
The purpose of this dissertation research was to develop a new wind tunnel to be used for aerosol research at the University of South Florida. Three specific aims had to be met for this study to be successful. They included: (1) designing a wind tunnel based on best practice information outlined in scientific literature, (2) constructing an operable wind tunnel to be used for aerosol research, and (3) characterizing wind tunnel performance by examining the wind tunnel velocity profile, turbulence intensity, and aerosol introduction/collection. The actual wind tunnel was constructed to a length of approximately 20 feet, a height of approximately 2 feet at its tallest point, and includes an entrance filter housing, a settling chamber, a contraction, a testing section, a diffuser, an exit filter housing, a fan, and exhaust duct. All components were designed and constructed using guidelines and best practices reported in the scientific literature.
Velocity profile measurements were the first way that this wind tunnel was characterized. In order to successfully obtain measurements, the wind tunnel cross section was divided into 16 equal quadrants. Five measurements were taken for each quadrant at each wind velocity. Target wind velocities for this research were 0.5 m/s, 1.0 m/s, and 2.0 m/s. Actual average wind velocities of 0.48 m/s, 1.00 m/s, and 2.04 m/s. All were within established limits reported in the scientific literature.
Turbulence intensity measurements were the second way that this wind tunnel was characterized. In order to successfully obtain measurements, the wind tunnel cross section was divided into 16 equal quadrants. Five measurements were taken for each quadrant at each wind velocity. Wind tunnels are typically designed to have the lowest turbulence intensity possible, generally below 10%. The overall average turbulence intensities for this wind tunnel at wind velocities of 0.5 m/s, 1.0 m/s, and 2.0 m/s were 9%, 10%, and 8% respectively. Overall turbulence intensity measurements were at or below 10%.
Isokinetic sampling was the final method used to characterize this wind tunnel by collecting and detecting aerosols traveling through the wind tunnel testing section. The wind tunnel was operated at wind velocities of 0.5 m/s, 1.0 m/s, and 2.0 m/s with isokinetic sampling flow rates of 15.4 L/min, 30.9 L/min, and 61.7 L/min respectively. Monodisperse fluorescent polystyrene latex spheres were used as the test aerosol because they are uniform in size and shape and can be detected by fluorometry. The Blaustein Multi-Jet Atomizer (BLAM) was used to generate monodisperse fluorescent polystyrene latex aerosol 0.5 µm and 2.0 µm particles from liquid suspensions. The Vilnius Aerosol Generator (VAG) was used to generate monodisperse fluorescent polystyrene latex aerosol of 6.0 µm and 12.0 µm particles from dry powders. Nitrogen gas was used for delivering test aerosols into the wind tunnel. Five experimental runs were completed for each particle size and wind velocity for a total of 60 experimental runs. Fluorescence was detected in all 60 samples with average mass concentrations ranging from 0.000050 ng/ml to 0.002703 ng/ml.
Based on velocity profile measurements, turbulence intensity measurements, and isokinetic sampling, the performance of University of South Florida wind tunnel was found to be excellent, indicating that it was designed and constructed appropriately. The wind tunnel can now successfully be used by researchers interested in evaluating industrial hygiene sampling equipment with aerosols ranging from 0.5 µm to 12.0 µm in moving air with velocities ranging from 0.5 m/s to 2.0 m/s.
33
Kim, Inn B. „Development and analysis of elastically tailored composite star shaped beam sections“. Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04062004-164703/unrestricted/kim%5Finn%5Fb%5F200312%5Fphd.pdf.
Der volle Inhalt der Quelle
34
Deng, Yun, und 鄧昀. „Design optimization of a micro wind turbine using computational fluid dynamics“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B4098770X.
Der volle Inhalt der Quelle
35
Ackerman, Christopher B. (Christopher Brian). „Structural quality assurance of wood light-frame construction subject to extreme wind hazards“. Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10621.
Der volle Inhalt der QuelleAnnotation:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.Includes bibliographical references (leaves 116-120).
by Christopher B. Ackerman.
M.S.
36
Carper, Christopher T. „Design and construction of vertical axis wind turbines using dual-layer vacuum-forming“. Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59899.
Der volle Inhalt der QuelleAnnotation:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 23).
How does one visualize wind? Is it the way trees bend in a strong gust or the way smoke is carried in a breeze? What if wind could be visualized using design, technology, and light? This thesis documents the design of a large scale display of vertical axis wind turbines that can be used to visualize wind. The intent is to build a matrix of several hundred turbines at MIT as part of the 150th anniversary celebration in 2011. The main focus is the appearance of the turbines, which are fabricated using a novel dual-layer vacuum-forming process. In it, one layer of pre-cut plastic is sandwiched between a polyurethane foam mold and a top layer of plastic which is heated and forms the seal for the vacuum. The top layer is subsequently removed and discarded leaving a formed part with clean, smooth edges. In order to optimize the manufacturing process and achieve repeatable results, variables such as heating time and material alignment had to be controlled. PETG and polystyrene were tested in a variety of configurations to maximize the respective strengths of each material and minimize their weaknesses. Each turbine is also designed to power its own LEDs. Potential designs for the necessary electronics are also included.
by Christopher T. Carper.
S.B.
37
Senders, Marc. „Suction caissons in sand as tripod foundations for offshore wind turbines“. University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0163.
Der volle Inhalt der QuelleAnnotation:
[Truncated abstract] The demand for offshore wind turbines is increasing in densely populated areas, such as Europe. These constructions are typically founded on a gravity foundation or a large 'mono pile'. Gravity foundations can only be used at locations where strong soils exist and water depths are limited. Costs associated with a 'mono pile' type foundation contribute to a very large percentage of the total investment costs. This research, therefore, focuses upon a different foundation for offshore wind turbines, namely suction caissons beneath a tripod. This foundation can be used in all kinds of soil types and is cheaper than the 'mono pile' foundation, both in the amount of steel used and installation costs. Cheaper foundations can contribute to a more competitive price for offshore wind energy in comparison with other energy resources. To date, there have been relatively few studies to investigate the behaviour of this type of foundation during the installation process and during operational and ultimate loading for seabed conditions comprising dense sand. Two types of investigations were performed during this research to determine the behaviour of suction caissons beneath a tripod. Firstly, an existing computer program was extended to predict the typical loading conditions for a tripod foundation. Secondly, centrifuge tests on small scale suction caissons were performed to investigate the behaviour during the installation and loading phases. The computer program developed helped to quantify the likely ranges of environmental loading on an offshore wind turbine. For a typical 3 MW wind turbine of 90 m height, the vertical load is low at around 7 MN. During storm conditions the horizontal hydrodynamic load can be in the order of 4 MN. During normal working conditions the horizontal aerodynamic loads can reach 0.4 MN, but can increase to 1.2 MN when the pitch system malfunctions and gusts reach 30 m/s. This aerodynamic load will result in a very large contribution to the overturning moment, due to the high action point of this load. When the wind turbine is placed on top of a tripod, these large moments are counteracted by a push-pull system. ... The development of differential pressure was found to depend on the soil permeability, the extraction speed and a consolidation effect. During cyclic loading no obvious signs of a decrease in resistance were observed. During very fast cyclic loading differential pressures developed, which could increase the drained frictional resistance by approximately 40%. All centrifuge tests results were used to develop methods to predict or back calculate the installation process of suction caissons in sand and layered soil, and the behaviour during tensile and cyclic loading. These methods all use the cone resistance as the main input parameter and predict the force (or required suction) as a function of time, for a given rate of pumping or uplift displacement, in addition to the variation of suction with penetration (or force with uplift displacement). These new methods provide a useful tool in designing a reliable foundation for offshore wind turbines consisting of a tripod arrangement of suction caissons embedded in dense sand.
38
DeLucia, Dominic. „A Parametric Study on Power Variation for Model Wind Turbine Arrays“. PDXScholar, 2013. http://pdxscholar.library.pdx.edu/open_access_etds/1120.
Der volle Inhalt der QuelleAnnotation:
This thesis presents the results of wind tunnel experiments performed for various model wind turbine arrays. The aim is to understand how siting affects power output. To optimize wind farm efficiency the experiments vary the parameters of the model wind turbines and the layout of the wind turbine array. The parameters include the alignment, height, spacing, and the rotational direction of the model wind turbines. These experiments employ mechanical torque sensors to simultaneously measure the torque and rotor angular velocity, which yields a direct measurement of the fluid mechanical power extracted by the turbine at multiple locations. For a 4 × 3 array, the power is calculated at the center turbine in each of the rows. Variations in wind farm efficiency ranging from 55% to 90% are observed between the 13 different layouts tested. Modifications to the layout of the wind turbine array clearly affects the power output of the wind turbines downstream. The results of such experiments highlight the importance of studying the relationship between wind farm layout and power output.
39
Larsson, Sparr Klara, und Mathias Muhonen. „Design- och simuleringsstudie av flödeshus och sensorkropp“. Thesis, KTH, Hållbar produktionsutveckling (ML), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277937.
Der volle Inhalt der QuelleAnnotation:
I detta arbete har ett koncept utvecklats för en flödesmätningsmetod med en intern sensorkropp samt bibehållen flödeshastighet. Denna mätmetod består av en sensorkropp i ett flödeshus där mätningen av flödet utförs med hjälp av pitotrörsberäkningar. Två olika lösningar presenteras i detta arbete, där skillnaderna grundar sig i utformningen av sensorkroppen. Sensorkroppens tvärsnitt är liknande för båda lösningarna. Den ena lösningen är rotationssymmetrisk i centrum av röret medan den andra går från vägg till vägg centrerat i röret. För att åstadkomma bibehållen flödeshastighet så utfördes beräkningar för att modellera flödeshuset, så att flödets tvärsnittsarea motsvarade arean i röret utan sensorkropp. I dessa beräkningar ingick även att kompensera för ökade solida ytor, då dessa ytor skapar gränsskikt där flödets hastighet sänks. Jämförelser mellan arbetets genererade koncept och uppdragsgivarens nuvarande produkter utfördes. Jämförelsen resulterade i flera områden där arbetets koncept skulle kunna komplettera redan befintliga produkter.In this project a concept for flow measurement has been developed, where there is an internal sensor body as well as a constant flow speed. This measurement method consists of a sensor body in a flow housing where the flow measurement is done using conventional pitot tube calculations. Two different solutions are presented in this work, the differences between the two solutions are based on the design of the sensor body. The cross-section of the sensor body is similar for both solutions, but one solution is rotationally symmetrical while the other goes from wall to wall. Both sensor bodies are centered in the tube. To accomplish continuous flow speed, calculations were made to model the flow housing, so the cross-sectional area of the flow corresponded to the area of the tube without the sensor body. In these calculations a compensation factor for increased solid surface area were included, as this area creates a boundary layer that lowers the flow speed and changes based on the design of the sensor body. Comparisons between the concept in this project and the commissioner's current products were made. This comparison resulted in several areas where this projects concept could complement existing products.
40
AYME, CARRIE NATHALIE. „Analyse des effets du vent sur les structures baties : constructions basses et structures elancees“. Nantes, 1987. http://www.theses.fr/1987NANT2051.
Der volle Inhalt der QuelleAnnotation:
Methode de calcul d'une force statique equivalente pour representer l'action du vent sur une structure basse type (halle industrielle), avec determination de coefficients de pression dans une approche reglementaire. Pour les structures elevees, ou l'aspect dynamique est preponderant, developpement d'un logiciel a partir du modele vickery-basu (structure elancee a section circulaire); determination des parametres aerodynamiques a partir de donnees experimentales
41
Langlois, Sébastien 1981. „Design of overhead transmission lines subject to localized high intensity wind“. Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99775.
Der volle Inhalt der QuelleAnnotation:
Wind loading considered in the design of overhead transmission lines is based on extreme values of synoptic wind, i.e. boundary layer wind originating from largescale meteorological pressure systems. Localized high intensity wind (HIW) storms such as tornadoes and downbursts are a different type of extreme wind frequently causing failures of overhead lines. This thesis covers the design aspects of overhead transmission lines when subject to localized HIW storms. A comprehensive review of the literature is included on the effects of such wind storms on lines and on mitigation measures. Furthermore, several options for the design of self-supporting transmission towers against localized HIW are discussed based on numerical simulations of several simple load cases on four examples of lattice structures.
42
Augustsson, Adam. „Reindeer Husbandry and Wind Power : Discourses surrounding the construction of IKEA's wind park on Glötesvålen and its local effects on reindeer husbandry“. Thesis, Malmö universitet, Malmö högskola, Institutionen för Urbana Studier (US), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42460.
Der volle Inhalt der QuelleAnnotation:
The exploitation of land in Northern Sweden has caused a significant depletion of grazing grounds for semi-domesticated reindeer. This is a threat to the indigenous Sami reindeer herders of Sweden, who rely on the grazing ground in order to sustainably feed their herds. In the last decade, a significant amount of grazing land has been lost due to the construction of wind power parks (WPP) in important grazing regions. This thesis examines the discourse surrounding a WPP built in Härjedalen for IKEA. The WPP was built on Glötesvålen, a unique highland used for grazing by Mittådalen, a local herding community. Through a dissection of electronic sources and semi-structured interviews, the author conducts a discourse analysis to identify the most prevalent narratives surrounding the construction of IKEA’s WPP on Glötesvålen. An inductive approach is used to identify underlying ideologies present in the discourse through a relevant theoretical framework. The results show a pervasive enthusiasm for the WPP as a pivot towards renewable energy which mirrors the ideology of ecological modernization. The results also find a critical narrative which lifts the uneven power dynamic experienced by reindeer herders. This narrative is understood through the lens of Spivak’s (2010) “Can the Subaltern Speak?”. An additional discourse found is the symbolic issue between industrial ecological transitioning and the right to reindeer husbandry as a cultural heritage.Exploateringen av mark i norra Sverige har orsakat en betydande förlust av betesmarker för renskötare. Detta hotar den svensk-samiska rennäringen, som förlitar sig på betesmarken för att hållbart mata sina hjordar. Under det senaste decenniet har en betydande mängd betesmark gått förlorad på grund av den ökande mängden vindkraftsparker (WPP) på, eller intillrenbetesmarker. Denna avhandling undersöker diskursen kring en WPP byggd i Härjedalen för IKEA. WPP byggdes på Glötesvålen, ett låg-fjäll som tidigare haft strategiskt viktiga betesmarker för samebyn Mittådalen. Genom en dissektion av elektroniska källor och halvstrukturerade intervjuer genomför författaren en diskursanalys för att identifiera de vanligaste narrativen om IKEAs vindkraftpark på Glötesvålen. En induktiv metod används för att identifiera underliggande ideologier som finns i diskursen genom ett relevant teoretisk ramverk. Resultaten visar en genomgripande entusiasm för vindkraft som ett steg mot förnybar energi. Detta narrativ speglar ideologin för ekologisk modernisering. Resultaten hittar också ett kritisk narrativ som lyfter den ojämna maktdynamiken som renskötarna upplever. Detta förstås genom Spivaks (2010) "Kan den underordnade tala?". Ytterligare en diskurs som upptäcks är symbolfrågan mellan industriell ekologisk omställning och bevarandet av renskötseln som kulturarv.
43
Minareci, Melike. „A FIELD INVESTIGATION FOR THE WIND LOAD PERFORMANCE OF VEGETATED GREENROOFS USING MONITORING SYSTEMS“. Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2355.
Der volle Inhalt der QuelleAnnotation:
Greenroof systems have been shown to be an environmentally friendly alternative based on various factors; such as, reduced lifecycle cost, improved air quality, ambient temperature reduction, stormwater management credit, sustainability and preservation of the environment. Recent research studies attempt to determine the construction methods of an ideal greenroof for environmental purposes, yet there is an absence of standards for the best design required to achieve acceptable structural performance and sustainability under wind loads. As a result, there is a need to document the effectiveness of greenroofs under high wind events by addressing the following questions: Do winds have an effect on greenroof material loss? Do greenroof materials modify local pressure conditions that would need a modification to current design codes? Does the level of vegetation establishment affect the material loss and pressure distribution? This thesis first focuses on vegetated greenroof construction techniques and issues along with some of the most recent studies conducted by UCF researchers. Then, the literature focuses on wind uplift of vegetated roofs constructed using different wind erosion control methods with respect to vegetation cover, geosynthetic liners, and wind breaks. As part of this research, two monitoring systems with a grid of very low differential pressure transducers and a high speed anemometer were designed and implemented on the East and West coasts of Florida to collect data for the pressure distribution across the greenroofs in relation to wind direction and speed. In addition to this, the design of this monitoring system with specific information about the sensing and data acquisition systems is presented. Subsequently, the analysis of the monitoring data compares the peak wind gusts for each time interval to their corresponding pressure measurement to obtain pressure coefficients identified at each pressure node on the roof. Based on this analysis, pressure changes for hurricane speed winds are predicted to have an overall average uplift pressure envelope within ASCE Code 7-05 design standards with vegetation cover enhancing sustainability under wind events. For future studies, controlled field investigations to reduce in situ limitations due to natural climatic conditions as well as long term monitoring are discussed as recommended studies for the evaluation of wind effects.M.S.C.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering MSCE
44
Ragon, Scott Alan. „Optimization of composite box-beam structures including effects of subcomponent interaction“. Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/43336.
Der volle Inhalt der QuelleAnnotation:
Minimum mass designs are obtained for a simple box beam structure subject to bending, torque and combined bending/torque load cases. These designs are obtained subject to point strain and linear buckling constraints. The present work differs from previous efforts in that special attention is payed to including the effects of subcomponent panel interaction in the optimal design process. Two different approaches are used to impose the buckling constraints. When the global approach is used, buckling constraints are imposed on the global structure via a linear eigenvalue analysis. This approach allows the subcomponent panels to interact in a realistic manner. The results obtained using this approach are compared to results obtained using a traditional, less expensive approach, called the local approach.
When the local approach is used, in-plane loads are extracted from the global model and used to impose buckling constraints on each subcomponent panel individually. In the global cases, it is found that there can be significant interaction between skin, spar, and rib design variables. This coupling is weak or nonexistent in the local designs. It is determined that weight savings of up to 7% may be obtained by using the global approach instead of the local approach to design these structures.
Several of the designs obtained using the linear buckling analysis are subjected to a geometrically nonlinear analysis. For the designs which were subjected to bending loads, the innermost rib panel begins to collapse at less than half the intended design load and in a mode different from that predicted by linear analysis. The discrepancy between the predicted linear and nonlinear responses is attributed to the effects of the nonlinear rib crushing load, and the parameter which controls this rib collapse failure mode is shown to be the rib thickness. The rib collapse failure mode may be avoided by increasing the rib thickness above the value obtained from the (linear analysis based) optimizer. It is concluded that it would be necessary to include geometric nonlinearities in the design optimization process if the true optimum in this case were to be found.Master of Science
45
Snæbjörnsson, Jónas Thór. „Full- and Model Scale Study of Wind Effects on a medium-rise Building in a built up Area“. Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap og teknologi, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-173.
Der volle Inhalt der QuelleAnnotation:
The present study deals with full- and model scale study of wind effects on a medium-rise building in a built up area. Most low-rise building experiments have been based on an isolated building placed in a relatively uniform terrain. Similarly, the very tall buildings often extend out from their environment in a similar fashion. However, buildings are constructed in various shapes and placed in different types of terrain and topography. Therefore, despite a number of studies made in the past, there are still problems that remain unsolved. As the majority of office- and residential buildings in populated areas fall in the intermediate height category, it should be of interest to examine the wind effects acting upon such a building, as well as its dynamic response. For this purpose, an experimental program was initiated utilising a combination of full-scale measurements and wind tunnel studies, where the fluctuating wind actions are evaluated from recorded simultaneous point pressure fluctuations. Recent improvements in experimental techniques and data handling enable a more detailed information gathering that should eventually lead to an improved understanding of the pressure field around buildings. The investigation studies, experimentally, the wind induced dynamic loading and response of a multi-story building of intermediate height. The presented work evolves on one hand around experimental data acquisition in both full- and model scale, whereas on the other it evolves around basic data reduction, understanding and interpretation of the acquired data. The objective of the study is, in a way, to attempt to provide a sound wind loading chain a la Davenport [29], in the form of data that would facilitate the study of the links connecting the main parameters i.e. Wind – Load – Response. This entails the definition of the relevant wind parameters, the description of the aerodynamic loading process, such as the time-dependent variations of pressure fluctuations on the building surface, and an investigation of the wind induced response of a medium-rise building. Information on the study-building and the experimental setup and procedures is given, for both full-scale and model scale. The full-scale and model scale data are systematically compared through the evaluation of descriptive parameters of both wind turbulence and surface pressures. In general, the evaluated full-scale parameters are found to be in qualitatively good agreement with the model scale parameters. However, the investigation revealed some characteristic differences between full-scale and model scale behaviour. These differences are largely related to the fact that significant variability is found to be inherent in the fullscale data, whereas considerably less variability seems to be associated with the wind tunnel data.
46
Szleper, Michele Lee. „Converging nozzle design for a subsonic wind tunnel to test heat sinks under impinging and parallel airflows“. Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17124.
Der volle Inhalt der Quelle
47
Yildirim, Ilyas. „Optimal Wind Bracing Systems For Multi-storey Steel Buildings“. Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610792/index.pdf.
Der volle Inhalt der QuelleAnnotation:
The major concern in the design of the multi-storey buildings is the structure to have enough lateral stability to resist wind forces. There are different ways to limit the lateral drift. First method is to use unbraced frame with moment-resisting connections. Second one is to use braced frames with moment-resisting connections. Third one is to use pin-jointed connections instead of moment-resisting one and using bracings. Finally braced frame with both moment-resisting and pin-jointed connections is a solution.
There are lots of bracing models and the designer should choose the appropriate one. This thesis investigates optimal lateral bracing systems in steel structures. The method selects appropriate sections for beams, columns and bracings, from a given steel section set, and obtains a design with least
weight. After obtaining the best designs in case of weight, cost analysis of all structures are carried out so that the most economical model is found. For this purpose evolution strategies optimization method is used which is a member of the evolutionary algorithms search techniques.
First optimum design of steel frames is introduced in the thesis. Then evolution strategies technique is explained. This is followed by some information about design loads and bracing systems are given. It is continued by the cost analysis of the models. Finally numerical examples are presented. Optimum designs of three different structures, comprising twelve different bracing models, are carried out. The calculations are carried out by a computer program (OPTSTEEL) which is recently developed to achieve size optimization design of
skeletal structures.
48
Way, Andrew Christopher. „A Study on the Design and Material Costs of Tall Wind Turbine Towers in South Africa“. Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95906.
Der volle Inhalt der QuelleAnnotation:
Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The aim of this project is to study the structural design and costing of various designs of tall wind turbine towers and the associated foundations in a South African context. Speci c design guidelines are proposed for the design of tubular steel, concrete and concrete-steel hybrid towers and foundations for hub heights of 80, 100 and 120m. Additionally, a conclusion will be made as to whether the concrete and hybrid towers are a viable alternative to steel towers at higher hub heights. To accomplish this, three of each type of tower (steel concrete and hybrid) and their foundations were designed according to the relevant design standards. The designs were then veri ed using the Abaqus nite element software. The costs of the designs for a South African environment were subsequently calculated according to the increases in material cost, as a function of the increase in hub height. It was found that for the chosen design assumptions, the foundations for the concrete and hybrid towers are less material intensive, and therefore cheaper, than the steel towers. The material costs of the concrete and hybrid towers were also shown to be lower than the material costs of the steel towers, especially at hub heights of 100 to 120m. For the circumstances in this project, it was found that an increase in hub height causes an increase in energy generation of 3.52 and 6.28 percent for 80m to 100m and 80m to 120m hub heights, respectively. It is therefore deduced that, given the trends in the design and cost associated with increasing hub heights, the concrete and hybrid towers become viable alternatives to the conventional steel towers at hub heights of 100 to 120m in height.
AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om die strukturele ontwerp en koste van verskillende soorte ho e wind turbines en die toepaslike fondamente vir 'n Suid-Afrikaanse konteks te bestudeer. Spesi eke riglyne word voorgestel vir die ontwerp van silindervormige staal, beton en beton-staal hibriede torings en fondamente vir naafhoogte van 80, 100 en 120m. 'n Gevolgtrekking oor die lewensvatbaarheid van die beton en hibriede torings, in vergelyking met die gewone staal torings teen naafhoogte van 100 tot 120m sal ook gemaak word. Met die bogenoemde as doel, is drie van elke tipe toring (staal, beton en hibried) en hul fondamente volgens die toepaslike standaarde ontwerp. Daarna is die integriteit van die ontwerpe getoets en bevestig deur gebruik van die Abaqus eindige-element-metode sagteware. Ten slotte, die kostes van die ontwerpe vir 'n Suid Afrikaanse omgewing is bereken en die verandering in materiaalkoste uitgedruk as 'n funksie van die verhoging in naafhoogte. Daar is gevind dat, vir die aannames in die ontwerp, die fondamente van die beton en hybrid torings minder materiaal benodig, en dus goedkoper is as die staal torings. Verder, is die materiaalkoste van die beton en hibriede torings laer as die van die staal torings, veral vir naafhoogtes van 100 tot 120m. Verder, is daar vir die omstandighede in hierdie projek gevind dat ho er naafhoogtes stygings in energie-opwekking van 3.52 persent vir naafhoogte stygings van 80m tot 100m, en stygings van 6.28 persent vir naafhoogte stygings van 80m tot 120m lewer. Daar word dus tot die gevolgtrekking gekom dat, gegewe die tendense in die ontwerp en materiaal koste wat verband hou met die verhoging van die naafhoogte, die beton en hibriede torings 'n lewensvatbare alternatief vir die konvensionele staal torings vir naafhoogtes van 100 tot 120m word.
49
Venkata, Vijai Kumar. „Development and testing of hurricane resistant laminated glass fiber reinforced composite window panels /“. free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426111.
Der volle Inhalt der Quelle
50
Unal, Sadullah Utku. „Design, Construction And Preliminary Testin Of An Aeroservoelastic Test Apparatus To Be Used In Ankara Wind Tunnel“. Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607034/index.pdf.
Der volle Inhalt der QuelleAnnotation:
In this thesis, an aeroservoelastic test appratus is designed to investigate the flutter phenomena in a low speed wind tunnel environment. Flutter is an aeroelastic instability that may occur at control surfaces of aircrafts and missiles. Aerodynamic, elastic, and inertial forces are involved in flutter. A mathematical model using aeroelastic equations of motion is derived to investigate flutter and is used as a basis to design the test setup. Simulations using this mathematical model are performed and critical flutter velocities and frequencies are found. Stiffness characteristics of the test setup are determined using the results of these simulations. The test setup is a two degrees of freedom system, with motions in pitch and plunge, and is controlled by a servomotor in the pitch degree of freedom. A NACA 0012 airfoil is used as a control surface in the test setup. Using this setup, the flutter phenomena is generated in Ankara Wind Tunnel (AWT) and experiments are conducted to validate the results of the theoretical aeroelastic mathematical model calculations.